AU2009238245A1

AU2009238245A1 - Machine Tool Bit Design

Info

Publication number: AU2009238245A1
Application number: AU2009238245A
Authority: AU
Inventors: Simon Dean Gischus; Ian Lachlan Kilpatrick
Original assignee: SIMON GISCHUS
Current assignee: SIMON GISCHUS
Priority date: 2009-11-13
Filing date: 2009-11-13
Publication date: 2011-03-31

Description

1 Machine Tool Bit Design Field of the Invention. The present invention relates to a machine tool bit. In particular, the present invention 5 relates to a machine tool bit having a failure control mechanism. Background Art. Machine tools are commonly used for the fabrication of a wide variety of components, and in particular metal components, by machining. Machine tools can perform a 10 number of functions, including drilling, tapping, reaming and milling, and the function performed by the machine tool is determined in part by the machine tool itself and in part by the choice of machine tool bit used in the machine tool. In conventional machine tools, such as hand operated tools, electric hand tools, 15 numerical control (NC) machines and computerized numerical control (CNC) machines, the bit comprises a drive section and a work section, wherein the drive section is held by the machine tool, and the work section is brought into contact with the component to be machined. 20 Due to the high mechanical stresses placed on machine tool bits, the bits may fail, particularly after extensive use, or if the material being machined is of high mechanical strength. While the failure of machine tool bits is inevitable, broken parts are often difficult to remove, and their removal not only reduces the operational time of the machine tool, but may also cause damage to the component being machined. 25 Thus, there would be an advantage if it were possible to provide a machine tool bit that, in the event of failure, could be quickly and easily removed from the component. In addition, there would be an advantage if, once failure had occurred, the machine tool bit could be reused, thereby extending its operational life. 30 It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

2 Throughout this specification, the term "comprising" and its grammatical equivalents shall be taken to have an inclusive meaning unless the context of use indicates otherwise. 5 Object of the Invention. It is an object of the present invention to provide a machine tool bit which may overcome at least some of the abovementioned disadvantages, or provide a useful or commercial choice. 10 In one aspect, the invention resides broadly in a machine tool bit comprising a work portion and a shank extending from the work portion, wherein the shank is provided with one or more regions of reduced mechanical strength. 15 A skilled addressee will understand that the term "work portion" refers to the function and location of the portion of the machine tool bit. In particular, the term "work portion" refers to the portion of the machine tool bit adapted to be brought into contact with the component to be machined. 20 The work portion may be provided with means for carrying out any suitable kind of work. For instance, the work portion may be provided with means for drilling, tapping, milling, reaming or the like. The shank may be of any suitable configuration. However, in a preferred embodiment 25 of the invention, the shank comprises a drive shaft. A skilled addressee will understand that the length of the drive shaft is not critical and, while the shape is also not critical, it is preferred that the drive shaft is substantially cylindrical. The shank may further be provided with connection means adapted to enable to the 30 machine tool bit to be connected to a machine tool. The connection means may be of any suitable form, although in some embodiments the connection means comprises a section having a particular configuration and adapted to engage with a correspondingly shaped receiving portion in the machine tool. For instance, the 3 connection means may comprise a portion of the shank having a square or hexagonal cross-section, although a skilled addressee will understand that any suitable cross sectional shape could be used. Alternatively, the connection means may comprise a slot, projection, recess, keyway or the like (or a combination thereof) adapted to 5 engage with corresponding receiving portion in the machine tool. Preferably the connection means are located at or adjacent an end of the machine tool bit furthest from the work portion, although a skilled addressee will understand that the connection means may be located at any suitable point in the shank. 10 Preferably, the driving force of the machine tool bit is provided by the machine tool. While any suitable force may be imparted to the machine tool bit by the machine tool, it is envisaged that, in preferred embodiments of the invention, the machine tool will provide a rotational force to the machine tool bit. 15 The one or more regions of reduced mechanical strength are, as previously stated, located in the shank of the machine tool bit. The one or more regions of reduced mechanical strength may be of any suitable configuration, and any suitable method of introducing reduced mechanical strength into the machine tool bit may be used. 20 The purpose of the one or more regions of reduced mechanical strength is to provide the machine tool bit with a designated point or region at which failure of the machine tool bit is likely to occur in the event that the mechanical stresses and strains within the machine tool bit reach or exceed a critical level. For instance, should the work portion of a conventional machine tool bit become caught or trapped in the component 25 to be machined, failure of the machine tool bit will often occur in the work portion. The broken work portion must then be removed from the component which may be both difficult and time-consuming. By contrast, providing the machine tool bit with one or more regions of reduced 30 mechanical weakness ensures that, in the event of failure, the machine tool bit will break at one or the regions of reduced mechanical weakness. Thus, the broken machine tool bit will be able to be removed from the component quickly and easily, and the machine tool will only be out of service for a relatively short period of time.

4 In some embodiments of the invention, the one or more regions of reduced mechanical strength may be fabricated from a material having reduced mechanical strength to the remainder of the machine tool bit (for instance the one or more regions 5 of reduced mechanical strength may be fabricated from a more brittle or ductile material to the remainder of the machine tool bit). Alternatively, the one or more regions of reduced mechanical strength may have a different cross-sectional shape to the rest of the shank (for instance, the one or more regions of reduced mechanical strength may have a square cross-section compared to a circular cross-section of the 10 rest of the shank). In other embodiments of the invention, the one or more regions of reduced mechanical strength may have a reduced cross-sectional area to compared to the remainder of the shank. In these embodiments of the invention, the one or more regions of reduced 15 mechanical strength may be created by forming a recess, notch, region of reduced diameter or channel in the shank to create the region of reduced mechanical strength. The recess, notch or channel may be a continuous channel or notch extending around the entire circumference of the shank, or may comprise one or more non-continuous channels or notches extending around at least a portion of the circumference of the 20 shank. By introducing one or more regions of reduced mechanical strength into the shank in this manner, it may be ensured that any mechanical failure of the machine tool bit will occur at the one or more regions of reduced mechanical strength. 25 The one or more regions of reduced mechanical strength may be located at any suitable point on the shank. However, it is preferred that the one or more regions of reduced mechanical strength may be located a sufficient distance from the work portion so as to ensure that, in the event of failure, the broken machine tool bit may be 30 retrieved easily from the component to be machined. In embodiments in which the shank is provided with a plurality of regions of reduced mechanical strength, the regions may be of the same type, or may differ from another 5 such that, in the even of a mechanical failure, a particular region fails first before the other regions. For instance, the plurality of regions may be provided with varying cross-sections such that a first failure will occur at the region having the smallest cross-section. In this way, the machine tool bit may be re-used until all of the regions 5 of reduced mechanical strength have failed. In some embodiments of the invention, the machine tool bit may be provided with a plurality of connection means. For instance, a first connection means may be provided at or adjacent the end of the shank furthest from the work portion of the 10 machine tool bit, with a first region of reduced mechanical strength being located intermediate the first connection means and the work portion. A second connection means may be provided at a point intermediate the work portion and the first region of reduced mechanical strength, with a second region of reduced mechanical strength located intermediate the second connection means and the work portion. If desired, a 15 third connection means may be provided still closer to the work portion at a point intermediate the work portion and the second region of reduced mechanical strength. Further connection means may be provided as desired in a similar manner. The advantage of this arrangement is that providing the regions of reduced mechanical strength above the work portion means that the broken machine tool bit may be 20 grasped and removed from the component being machined due to the fact that the broken shank will always protrude above the component. In addition, providing multiple regions of reduced mechanical strength means that the machine tool bit may be re-used after a mechanical failure, thereby extending the life of the machine tool bit. This is simply not possible with conventional machine tool bits. 25 It will be understood that, in some embodiments of the invention, the entire shank may be of a lesser mechanical strength than the work portion. For instance, the entire shank may have a reduced diameter in comparison to that of the work portion. 30 In another aspect, the invention resides broadly in a machine tool bit having one or more regions of reduced mechanical strength, such that, upon the accumulation of sufficient mechanical stresses, the machine tool bit is adapted to fail at, at least one of the one or more regions of reduced mechanical strength.

6 Although the present invention has been described largely in connection with a machine tool bit, a skilled addressee will understand that the present invention could also be used in connection with other items which require the use of bits. For 5 instance, the present invention could be adapted for use in manual hand-held tools, hand-held power tools, small-scale industrial equipment or the like. Brief Description of the Drawings. An embodiment of the invention will be described with reference to the following 10 drawings in which: Figure 1 illustrates a plan view of a machine tool bit according to an embodiment of the present invention; Figure 2 illustrates a plan view of a machine tool bit according to an embodiment of the present invention; 15 Figure 3 illustrates a plan view of a machine tool bit according to an embodiment of the present invention; Figure 4 illustrates a plan view of a machine tool bit according to an embodiment of the present invention; Figure 5 illustrates a plan view of a machine tool bit according to an 20 embodiment of the present invention; and Figure 6 illustrates a plan view of a machine tool bit according to an embodiment of the present invention. Detailed Description of the Drawings. 25 It will be appreciated that the drawings have been provided for the purposes of illustrating preferred embodiments of the present invention and that the invention should not be considered to be limited solely to the features as shown in the drawings. In Figure 1 there is shown a machine tool bit 10 according to a first embodiment of 3 0 the present invention. The machine tool bit 10 is a drill bit. The machine tool bit 10 comprises a work portion 11 to be brought into contact with a component (not shown) to be drilled and a shank 12 adapted for connection to a 7 machine tool, hand-held drill or the like (not shown). The shank 12 comprises a drive shaft 13 having an area of reduced mechanical strength therein, in the form of an annular notch 14 cut or formed in the drive shaft 13. 5 The diameter of the annular notch 14 is less than that of the drive shaft 13 and the work portion 11 meaning that the annular notch is the mechanically weakest point of the entire machine tool bit 10. Thus in the event of the mechanical stresses in the machine tool bit 10 exceeding a critical level, the machine tool bit 10 will fail (by breaking, fracturing and so on) at the annular notch 14, meaning that the work portion 10 11 of the machine tool bit 10 remains undamaged. By ensuring that mechanical failure of the machine tool bit 10 occurs at the annular notch 14, it may be ensured that, when failure occurs, the failure does not occur in the work portion 11. This means that the broken piece of the machine tool bit 10 may be 15 removed from the component (not shown) being drilled quickly, easily and with minimal risk of damage to the component. In Figure 2, there is shown a machine tool bit 20 according to a second embodiment of the present invention. The machine tool bit 20 is a mill bit. 20 The machine tool bit 20 comprises a work portion 21 to be brought into contact with a component (not shown) to be milled and a shank 22 adapted for connection to a machine tool, hand-held power tool or the like (not shown). 25 The shank 22 comprises a drive shaft 23 having an area of reduced mechanical strength therein, in the form of an annular notch 24 cut or formed in the drive shaft 23. The diameter of the annular notch 24 is less than that of the drive shaft 23 and the work portion 21 meaning that the annular notch 24 is the mechanically weakest point of the entire machine tool bit 20. Thus in the event of the mechanical stresses in the 30 machine tool bit 20 exceeding a critical level, the machine tool bit 20 will fail (by breaking, fracturing and so on) at the annular notch 24, meaning that the work portion 21 of the machine tool bit 20 remains undamaged and may be removed quickly and easily from the component.

8 The shank 22 further comprises connection means 25 to be received in a corresponding receiving portion (not shown) of a machine tool (not shown). In the embodiment of the invention shown in Figure 2, the connection means 25 includes a 5 slot 26 adapted for engagement with a corresponding part (such as a bar or the like) in the machine tool. In Figure 3, there is shown a machine tool bit 30 according to a third embodiment of the present invention. The machine tool bit 30 is a bit for a reamer. 10 The machine tool bit 30 comprises a work portion 31 to be brought into contact with a component (not shown) to be reamed and a shank 32 adapted for connection to a machine tool, hand-held power tool or the like (not shown). 15 The shank 32 comprises a drive shaft 33 having an area of reduced mechanical strength therein, in the form of an annular notch 34 cut or formed in the drive shaft 33. The diameter of the annular notch 34 is less than that of the drive shaft 33 and the work portion 31 meaning that the annular notch 34 is the mechanically weakest point of the entire machine tool bit 30. Thus in the event of the mechanical stresses in the 20 machine tool bit 30 exceeding a critical level, the machine tool bit 30 will fail (by breaking, fracturing and so on) at the annular notch 34, meaning that the work portion 31 of the machine tool bit 30 remains undamaged and may be removed quickly and easily from the component. 25 The machine tool bit 30 of Figure 3 further comprises connection means 35 located at the end of the shank 32 furthest from the work portion 31. The connection means 35 are adapted for connection to a receiving portion (not shown) in a machine tool (not shown) such that the machine tool bit 30 may be connected to and retained by the machine tool (not shown) during use. Further, the machine tool (not shown) is 30 adapted to transfer the driving force to the machine tool bit 30 by imparting a rotational force to the machine tool bit 30. In Figure 4, there is shown a machine tool bit 40 according to a fourth embodiment of 9 the present invention. The machine tool bit 40 is a bit for a tapping bit. The machine tool bit 40 comprises a work portion 41 to be brought into contact with a component (not shown) to be tapped and a shank 42 adapted for connection to a S machine tool, hand-held power tool or the like (not shown). The shank 42 comprises a drive shaft 43 having an area of reduced mechanical strength therein, in the form of an annular notch 44 cut or formed in the drive shaft 43. The diameter of the annular notch 44 is less than that of the drive shaft 43 and the 10 work portion 41 meaning that the annular notch 44 is the mechanically weakest point of the entire machine tool bit 40. Thus in the event of the mechanical stresses in the machine tool bit 40 exceeding a critical level, the machine tool bit 40 will fail (by breaking, fracturing and so on) at the annular notch 44, meaning that the work portion 41 of the machine tool bit 40 remains undamaged and may be removed quickly and 15 easily from the component. The machine tool bit 40 of Figure 4 further comprises connection means 45 located at the end of the shank 42 furthest from the work portion 41. The connection means 45 are adapted for connection to a receiving portion (not shown) in a machine tool (not 20 shown) such that the machine tool bit 40 may be connected to and retained by the machine tool (not shown) during use. Further, the machine tool (not shown) is adapted to transfer the driving force to the machine tool bit 40 by imparting a rotational force to the machine tool bit 40 25 In Figure 5 there is shown a machine tool bit 50 according to an alternative embodiment of the present invention. The machine tool bit 50 is essentially the same as that illustrated in Figure 1, except that the shank 51 of the machine tool bit 50 is of a reduced diameter along its entire length in comparison to the work portion 52. 30 In Figure 6 there is shown a machine tool bit 60 according to an alternative embodiment of the present invention. The machine tool bit 60 is essentially the same as that illustrated in Figure 3, except that the shank 61 of the machine tool bit 60 is provided with a first connection means 62 and a first annular notch 63, as well as a 10 second connection means 64 and a second annular notch 65. In this embodiment of the invention, the first annular notch 64 may be of reduced diameter to the second annular notch 65 such that failure of the machine tool bit 60 5 occurs first in the first annular notch 64. Once failure has occurred, the first connection means 62 may be released from the machine tool (not shown) and the second connection means 64 may then be connected to the machine tool (not shown), thereby extending the useful life of the machine tool bit 60. 10 In the event of a second mechanical failure, the failure will occur at the second annular notch 65, meaning that the work portion 66 may still be easily and quickly retrieved from the component (not shown) being machined. Those skilled in the art will appreciate that the present invention may be susceptible to 15 variations and modifications other than those specifically described. It will be understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope.

Claims

1. A machine tool bit comprising a work portion and a shank extending from the work portion, wherein the shank is provided with one or 5 more regions of reduced mechanical strength.

2. A machine tool bit according to claim 1 wherein the shank comprises a drive shaft.

3. A machine tool bit according to claim 1 or claim 2 wherein the shank is adapted for connection to a machine tool or hand-held power tool. 10

4. A machine tool bit according to any one of the preceding claims wherein the one or more regions of reduced mechanical strength comprise one or more notches, channels, regions of reduced diameter or recesses in the surface of the shank.

5. A machine tool bit according to any one of the preceding claims 15 wherein each of the one or more regions of reduced mechanical strength comprise a single annular notch extending about the circumference of the shank.

6. A machine tool bit according to any one of the preceding claims wherein the machine tool bit comprises one or more connection 20 means adapted to connect the machine tool bit to a machine tool.

7. A machine tool bit according to claim 6 wherein a first connection means is located at or adjacent an end of the machine tool bit furthest from the work portion, and a first region of reduced mechanical strength is located intermediate the first connection 25 means and the work portion..

8. A machine tool bit according to claim 7 wherein a second connection means is located intermediate the first region of reduced mechanical strength and the work portion.

9. A machine tool bit according to any one of the preceding claims 30 wherein the work portion is adapted to be brought into contact with a component to be machined.

10. A machine tool bit according to any one of the preceding claims wherein the machine tool bit is adapted for drilling, milling, 12 reaming or tapping a component to be machined.

11. A machine tool bit having one or more regions of reduced mechanical strength, such that, upon the accumulation of sufficient mechanical stresses, the machine tool bit is adapted to fail at, at least one of the 5 one or more regions of reduced mechanical strength.

12. A machine tool bit substantially as hereinbefore described with reference to the drawings.