WEDDERBURN, Ian Norman (11 Harry Road, Providentia, 6070 Port Elizaberth, ZA)
HATTINGH, Daniel Gerhardus (29 Nile Road, Perridgevale, 6000 Port Elizaberth, ZA)
WEDDERBURN, Ian Norman (11 Harry Road, Providentia, 6070 Port Elizaberth, ZA)
CLAIMS:
1. An undercut tooling arrangement including: a tool holder being securable to a rotary machine; a cutting tool being displaceably securable to the tool holder, the cutting tool being transversally displaceable relative to an axis of rotation of the tool holder when secured thereto; and a displacement mechanism for selectively displacing the cutting tool relative to the tool holder.
2. The undercut tooling arrangement of claim 1 wherein the displacement mechanism includes a guide rod secured to and extending from the cutting tool, and a threaded engagement member engaging a threaded part of the guide rod, in order for rotation of the threaded engagement member to cause displacement of the cutting tool.
3. The undercut tooling arrangement of claim 2 wherein the guide rod extends from the tool holder in order for the threaded part to be located outside the tool holder.
4. The undercut tooling arrangement of claim 2 or claim 3 wherein the threaded engagement member is a threaded nut.
5. The undercut tooling arrangement of any one of the preceding claims including biasing means for biasing the cutting tool in the direction of a cutting edge of the cutting tool.
6. The undercut tooling arrangement of claim 5 wherein the biasing means is sandwiched between the adjustment nut and the tool holder in order for displacement of the adjustment nut to result in adjustment of the compression of the biasing means.
7. The undercut tooling arrangement of claim 5 or 6 wherein the biasing means is in the form of a helical spring.
8. The undercut tooling arrangement of any one of the preceding claims wherein the cutting tool is receivable inside a slot provided in the tool holder, in order for the cutting tool to be slideable within the slot.
9. A method of taking a core sample form a steel object, including the steps of: cutting an annular hole in the object, forming an undercut at the bottom of the hole; and removing a cylindrical sample formed by the cutting process.
10. The method of claim 9 wherein the undercut is formed- using the undercutting tool of any one of claims 1 to 8.
11. The method of claim 9 and 10 wherein the cylindrical sample is removed by imparting a torque on the sample, in order for the sample to shear from the object at the undercut end. |
UNDERCUT TOOLING ARRANGEMENT
BACKGROUND OF THE INVENTION
THIS invention relates to an undercut tooling arrangement, and more particularly, but not exclusively, to an undercut tooling arrangement suitable for use in a rotary single axis cutting machine.
Undercutting is a standard machining operation in which a portion of material at an underside of an object or formation is cut away in order to form an overhang in relief.
Undercutting is generally performed utilizing a lathe turning machine, or any other cutting machine that can provide multiple axial adjustments required to perform the undercut. When using a iathe, the work piece in which the undercut is to be performed is rotated, and the cutting tool can be displaced axially and radially relative to the work piece in order to effect the undercut.
It will however be appreciated that a required multiple axis machine, such as a lathe, is not always readily available, and standard single axis rotary cutting machines (such as a drill press) does not have sufficient degrees of freedom to perform a required undercut. This problem is exacerbated when an undercut is to be formed on an object in situ.
One example of an application where it would be beneficial if an undercut could be made in-situ is in the removal of core samples from a body of material to be sampled. A first step in the sample removal process would be to cut an annular groove about the sample to be removed. It will however be appreciated that after cutting of such groove, the sample will still be connected to the body at the lower end thereof, and a very large
torque would be required to break the sample from the body in a twisting action. However, the required torque will be substantially reduced if it was possible to form a radially inwardly directed undercut at the bottom of the sample.
It is accordingly an object of the invention to provide an undercut tooling arrangement which will, at least partially, alleviate the above disadvantage, and/or to provide an undercut tooling arrangement that will be a useful alternative to existing undercut tooling arrangements. It is in particular also an object of the invention to provide an undercut tooling arrangement that can be used in a rotary single axis machine such as for example a drill press.
SUMMARY OF THE INVENTION
According to the invention there is provided an undercut tooling arrangement including: a tool holder being securable to a rotary machine; a cutting tool being displaceably securable to the tool holder, the cutting tool being transversally displaceable relative to an axis of rotation of the tool holder when secured thereto; and a displacement mechanism for displacing the cutting tool relative to the tool holder.
The displacement mechanism may comprise a guide rod extending from the cutting tool, and a threaded engagement member engaging a threaded part of the guide rod, in order for rotation of the threaded engagement member to cause displacement of the cutting tool.
The threaded engagement member may be a threaded nut.
The undercutting tool preferably includes biasing means for biasing the cutting tool in the direction of a cutting edge of the cutting tool.
Preferably the biasing means is in the form of a helical spring.
The cutting tool may be receivable inside a slot provided in the tool holder, in order for the cutting tool to be slideable within the slot.
The guide rod extends from the tool holder in order for the threaded section to be located outside the tool holder.
The biasing means is sandwiched between the adjustment nut and the tool holder in order for displacement of the adjustment nut to result in adjustment of the compression of the biasing means.
There is provided for the undercut tooling arrangement of this invention to be used in combination with the applicant's co-pending patent application No. ZA2008/04630 entitled "Friction Welding Apparatus", the content of which is incorporated herein by reference.
According to a further aspect of the invention there is provided a method of taking a core sample from a steel object, the method including the steps of: cutting an annular hole in the object, forming an undercut at the bottom of the hole; and removing a cylindrical sample formed by the cutting process.
There is provided for the undercut to be formed using the undercut tool as described above.
The cylindrical sample may be removed by imparting a torque on the sample, in order for the sample to shear from the object at the undercut end.
-A-
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention is described by way of a non- limiting example, and with reference to the accompanying figures in which:
Figure 1 is a perspective view of the undercut tooling arrangement in accordance with an embodiment of the invention;
Figure 2 is a side view of the undercut tooling arrangement of Figure 1 ;
Figure 3 is a cross-sectional side view of an annular aperture in which an undercut has been formed; and
Figure 4 shows the undercut tooling arrangement of figure 1 in position in the aperture of figure 3.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, in which like numerals indicate like features, a non-limiting example of an undercut tooling arrangement in accordance with the invention is indicated by reference numeral 10. The undercut tooling arrangement 10 includes a tool holder 20, a cutting tool 30 slideably secured to the tool holder 20, and a biasing arrangement 40 for biasing the cutting tool 30 relative to the tool holder 20.
The undercut tooling arrangement 10 is used to form an undercut 16 in an aperture 14 provided in an object 12 (which may for example be in the form of the wall of a pipe). The undercut tooling arrangement 10 is adapted to
be used in combination with a rotary single axis machine, such as a drill press (not shown) or the customized friction welder apparatus of the applicant's prior application referenced above. Importantly, it is adapted for use in a machine that causes the tool holder to rotate, but which does not allow sideways movement of the tool holder that would be required for forming an undercut.
The tool holder 20 comprises a body 21 , in which is provided a slot 23 for slideably receiving a cutting tool 30. A shank 22 extends from the body 21 along an axis of rotation of the tool holder 20, and in use is connected to the rotating single axis machine, which therefore causes the tool holder 20, and therefore the cutting tool 30, to rotate.
The cutting tool 30 includes a base 31 that is slideably receivable inside the slot 23 provided in the tool holder 20, and a cutting member that extends form the base 31 and terminates in a cutting edge 32. The shape and configuration of the cutting edge 32 is determined by the geometry of the undercut to be formed. In this example the undercut 16 is formed in the inner wall of an annular aperture 14 provided in an object, but it will also be appreciated that the cutting tool assembly 10 may be adapted to form an undercut (not shown) in an outer wall of an aperture. This will be done by transversally displacing the undercut tool to the other end of the tool holder, and the configuration of the tool will essentially stay the same.
As described above, the cutting tool 30 is transversely displaceable relative to the tool holder 20 so as to provide the additional axis of displacement required to form the undercut. However, a transverse force will have to be exerted on the cutting edge 32, and therefore on the cutting tool 30, in order to force the cutting edge 32 into abutment with the material to be removed. This is achieved by providing an adjustable displacement and biasing arrangement 40 for imparting a bias, and thus a cutting force, on the cutting tool 30. Although it may be possible to omit the biasing means, and to continuously adjust the nut 43 to maintain a cutting force, the arrangement that includes a biasing means is the preferred option.
The displacement and biasing arrangement 40 (best seen in figure 2) comprises a guiding rod 41 that extends through a bore (not shown) provided in the base 31 of the cutting tool 30. The guiding rod 41 is secured to the cutting tool 30, in order for displacement of the tool holder 30 to result in equivalent displacement of the guiding rod 41 and vice versa. Biasing means 44 in the form of a helical spring is located on the guiding rod 41 , and is sandwiched between part of the tool holder 20 and an adjustment formation 43 located on the guiding rod. The adjustment formation 43 is typically in the form of a threaded nut that engages a complementary threaded portion of the guiding rod.
When the adjustment nut is displaced towards the tool holder 20, the spring ■ 44 is compressed, thus in return urging the adjustment formation 43 and thus the guiding rod 41 , transversely away from the tool holder 20. This bias is then also transmitted to the cutting tool 30, and the cutting tool is thus forced to abut a surface to be undercut. The adjustment means may be further adjusted if the cutting bias, and thus cutting force, is to be increased. It will be understood that a conceptually similar arrangement can also be utilized to bias the cutting tool towards an opposite direction.
In use the undercut tooling arrangement 10 will be connected to a suitable rotary drive means, and the cutting tool 30 will be located inside the aperture in which the undercut is to be formed. Once the cutting tool 30 is in position, the adjustment nut 41 will be adjusted so as to increase the bias up to a point where a sufficient abutment or cutting force is exerted by the cutting edge onto the surface to be undercut. The rotary drive means can now be rotated, and the undercut will be formed by the cutting tool. It will also be appreciated that the adjustment nut can be adjusted at any stage during the formation of the undercut should it be desired to readjust the bias exerted by the biasing arrangement.
The inventors believe that this novel and inventive undercut tooling arrangement will be useful in industry, and that it will at least partially
alleviate the shortcomings associated with existing tools and devices for forming undercuts.
In particular, it is foreseen that the undercutting tool will be particularly useful in the process of taking non-penetrating core samples from the walls of pipes and or vessels. Such method will typically include: cutting an annular hole in the object, forming an undercut at the bottom of the hole using the undercut tool; and removing a cylindrical sample formed by the cutting process.
After the core sample has been removed, the blind hole remaining after the sample has been removed can be sealed by using a friction welding process utilizing the friction welding apparatus as disclosed in the applicants co-pending patent application ZA2008/04630, the content of which is incorporated herein by reference.
It will be appreciated that the above is only one embodiment of the invention and that there may be many variations without departing from the spirit and/or scope of the invention.
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