The present disclosure relates to cutting tools, in particular for cutting metals, and, more particularly, to a tooling cartridge that combines structural and engineering features to provide an interface for precision machining. The tooling cartridge includes a precision adjustment mechanism generally based on the merged functions of a differential screw and a wedge mechanism and provides a cutting force support in optimal domain, which reduces or eliminates backlash in the adjustment loop and imparts a stress control to the system.
In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.
Conventional tool cartridges, particularly ISO tool cartridges, for finish operations have a tool cartridge with a screw to bear against a cutting insert to hold it in a desired seated position for machining operations.
The conventional tool cartridge 10 has a body 14 that represents an essentially ridged structure. In use and to raise a vertex 16 of the cutting insert 18, one of two possibilities have to be executed: 1) a clamping screw has to be loosen, an adjustment performed, a clamp screw tighten, the adjustment should be checked and any correction made before the process is completed; or 2) a clamping screw has to be pre-tightened arbitrarily to allow the clamping screw to stretch enough to provide an adjustment range. Both methods 1) and 2) are criticized by typical machinists on the shop floor.
Another problem of the conventional design is a negative gain of resolution.
A further problem of the conventional design is a high expansion stress of the clamping screw 20, which is stretched by adjustment, and the high compression stress of the adjustment screw, which is trying to bend the rigid structure of cartridge body 14. Neither stress state is ideal.
U.S. Pat. No. 5,066,173 describes a boring bar in which a slot with a recess is introduced into the boring bar to allow the front of the cartridge to be flexible enough to reduce the stress on the clamping screw as well as on the adjustment screw. However, the disadvantage of this design is the low resolution of adjustment as it depends solely on the thread pitch of the screw and the adjustment screw resides in the cutter body (and not within the cartridge itself).
U.S. Pat. No. 7,753,626 discloses a cartridge that has a differential screw mechanism. However, the cartridge does not address the cantilever problem and the clamping screw problem discussed above.
Advantages of embodiments of the disclosed adjustment arrangement include, but are not limited by, one or more of the following: 1) high resolution of adjustment, which is improved by an introduced angle between a centroid axis of the adjustment mechanism and a long axis of the cartridge body during adjustment; 2) transverse of adjustment contact domain further forward under cutting edge to realize a longer lever and reduce cantilever; 3) better support against cutting force and reduce contact stress in adjustment mechanism; 4) reduced stress in the clamping screw; and 5) easier access to the adjustment screw and simplified adjustment procedure.
In additional embodiments, simplifying manufacturing of adjustment kit adjacent threads is manufactured using combination of standard metric and imperial threads. This is given a great economical effect to employ close but different pitches based on close diameters without specifying non-standard threads.
An exemplary embodiment of a tool cartridge for a material removal tool comprises a cartridge body, an axial adjustment screw at a first end of the cartridge body, an opening for a clamping screw proximate the first end of the cartridge body, a seat for a cutting tool insert at a second end of the cartridge body, a recess extending through at least a portion of the cartridge body from a first side toward a second side, a long axis of the recess non-parallel to a long axis of the cartridge body and at least a portion of the recess open to a bottom side of the cartridge body, and a threaded opening for a differential screw proximate the second end and positioned longitudinally between the opening for the clamping screw and at least a portion of the seat, wherein a thread axis of the threaded opening for the differential screw is at an angle G relative to a long axis of the cartridge body.
An exemplary embodiment of a material removal tool comprises a body and a plurality of tool cartridges. The tool cartridges comprises a cartridge body, an axial adjustment screw at a first end of the cartridge body, an opening for a clamping screw proximate the first end of the cartridge body, a seat for a cutting tool insert at a second end of the cartridge body, a recess extending through at least a portion of the cartridge body from a first side toward a second side, a long axis of the recess non-parallel to a long axis of the cartridge body and at least a portion of the recess open to a bottom side of the cartridge body, and a threaded opening for a differential screw proximate the second end and positioned longitudinally between the opening for the clamping screw and at least a portion of the seat, wherein a thread axis of the threaded opening for the differential screw is at an angle G relative to a long axis of the cartridge body.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The following detailed description can be read in connection with the accompanying drawings in which like numerals designate like elements and in which:
Other features of the exemplary tool cartridge 100 include an axial adjustment screw 120 at a first end 122 of the cartridge body 102. In the exemplary embodiment shown in
Other features of the exemplary tool cartridge 100 also include an opening 130 for a clamping screw 132. In the exemplary embodiment shown in
Other features of the exemplary tool cartridge 100 further include a seat 140 for a cutting tool insert (not shown in
Additional features of the exemplary tool cartridge 100 include a recess 160. In the exemplary embodiment shown in
Further features of the exemplary tool cartridge 100 include a threaded opening 170 for a differential screw 172. In the exemplary embodiment shown in
The axis 174, forms angle G to bottom surface 114 of the cartridge body 102. This allows every unitary move in the direction of differential screw axis 174 to be reduced 1/sin(G) times to conform to the following relationship:
Heff=H sin(G)
where Heff is the effective adjustment vector of movement, H is the vector of movement of the differential screw 172 (which corresponds to the axis 174).
For an example if G=60 degrees, Heff=H (0.866), which results in an adjustment resolution that is 15% more fine than for G=90 degrees. At an angle G of 45 degrees, the improvement in the resolution of adjustment will be 41% more precise. Reduction of angle G towards 0 has geometrical constrains based on the design envelop of the cartridge body. In general Gmin>ATAN (F/L). In exemplary embodiments, 89.9°>G>30°.
By the above relationship and positions, the differential screw 172 functions as a differential wedge mechanism and imparts finer control to the adjustment of the position of the cutting tool insert 200 on the material removal tool. For example, the angle G positions the features of the translating mechanism such as differential screw 172 and other associated components so that the vertical movement (i.e., in the Y-axis direction) relative to a baseline B of the second end 142 of the tool cartridge body 102 (and any associated cutting tool insert mounted thereon) per a thread length of the differential screw 172 is reduced. This results in smaller vertical movement and finer incremental control of the position of those portions of the tool cartridge.
Another aspect of the disclosed tool cartridge is that incorporating both the flexibility of the tool cartridge body 102 about center of rotation 300 due to the recess 160 and the control functions of the differential wedge mechanism allows significant reduction in stresses generated in the clamping screw 132 and in the threads of differential screw 172.
For example, a still further feature of the exemplary tool cartridge 100 includes a pad 500 positioned in the threaded opening 170 for the differential screw 172 at the bottom surface 110 of the cartridge body 102. This feature can be seen in, for example,
In exemplary embodiments, differential screw 172 has an external thread of pitch P1 on a first threaded portion located at one end and is positioned in an angle-based threaded opening 170 of cartridge body 102. The other end of the differential screw 172 has a second threaded portion with an external thread of pitch P2 and of the same lead and is engaged with internal threads of a first threaded portion of pad 500, which has pitch P1.
The use of different pitches can provide increased resolution of adjustment without specifying non-standard threads. If only metric or only imperial threads are used for both ends of the differential screw, resolution of adjustment will be relatively coarse as difference between pitches of threads. For example, if one end is standard M10×1.5 and fine pitch is M10×1.25, than the difference in pitches is 1.5−1.25=0.25 mm. As a result, one turn of the differential screw will adjust the position of the reference point on the insert about 0.25 mm. In contrast, if standard m10×1.5 thread would be combined with standard ⅜″-16 thread (pitch=25.4 mm/16=1.5875 mm) the difference of the pitches will be 1.5875−1.5=.0875 mm. This is 2.9 times finer (or more precise) than the prior situation and provides increased resolution of adjustment.
When the differential screw 172 is turned, it moves into and out of the threaded opening 170. This translation motion along axis 174 generates a force F, which acts through the pad 500 on the adjustment support point 400 and generates a reaction force Feff. This reaction force Feff causes the cartridge body 102 to bend and generates stresses, for example on the clamping screw 132. In this respect, the shape of pad 500 provides a reduced applied force F that bends the tool cartridge 102 in accordance with following equation:
F=Feff sin(G)
For G=60 degrees, the reduction in force is 15%.
In another aspect, the surface 504 of the pad 500 has a large radius. This large radius reduces contact stress and deformations by converting point contact to the linear contact, which, in turn, will increase longevity of cartridge 100 components.
The pad 500 can be secured in the opening 170 to be non-rotating. For example and as shown, for example in
A logo or other identifying information can be incorporated onto the surface 504 of the pad 500. For example, the pad 500 or a portion thereof, including the surface 504, can be manufactured of extruded polygon with cross-section style of any known polygon or other shapes which transfer torque or prevent rotation upon their native shape. An example of an anti-rotating shape can be a tri-lobe shape 602, with or without a printed logo, such as that for Coromant Capto®.
The recess 160 contributes to the flexibility of the cartridge body 102. Suitable parameters to size and locate the recess 160 can be developed using Finite Element Analysis (FEA).
The tool, such as driver or wrench 740, including a light projection device, such as laser beam 722, can be used to adjust a control point 302 of a cutting tool insert mounted in a tool cartridge 100. To do so, one can rotate the differential screw 172 with the tool 740 to position light from the light projection device with reference to one or more of the plurality of marks 720 on the surface of the cartridge body 102.
In another aspect, centrifugal force can be considered for the fine adjustment of the tool cartridge 100.
F=0.01097M R N2
where M=the mass in kg, R=radius of center of mass in meters and N=rpm.
Using this information, an engineering calculation was performed on an example material removal tool—a boring bar of diameter Ø70.0 mm. The results of these calculations are shown in
Although described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without department from the spirit and scope of the invention as defined in the appended claims.
Number | Name | Date | Kind |
---|---|---|---|
2998737 | Yogus et al. | Sep 1961 | A |
3102441 | Milewski | Sep 1963 | A |
3195376 | Bader | Jul 1965 | A |
3236125 | Lundgren | Feb 1966 | A |
3427904 | Arendt | Feb 1969 | A |
3755868 | LaForge et al. | Sep 1973 | A |
4040156 | Tack | Aug 1977 | A |
4428704 | Kalokhe | Jan 1984 | A |
4547100 | Naccarato et al. | Oct 1985 | A |
4692069 | Kieninger | Sep 1987 | A |
4786217 | Johne | Nov 1988 | A |
4878787 | Hunt | Nov 1989 | A |
5066173 | Gaffan et al. | Nov 1991 | A |
5709510 | Scheer | Jan 1998 | A |
7108395 | Correa | Sep 2006 | B2 |
7753626 | Musil et al. | Jul 2010 | B2 |
7993023 | Wang | Aug 2011 | B2 |
8118444 | Nevin | Feb 2012 | B2 |
20060140730 | Schlagenhauf et al. | Jun 2006 | A1 |
20070084320 | Frank et al. | Apr 2007 | A1 |
20090279963 | D'Andrea | Nov 2009 | A1 |
20110188951 | Mergenthaler | Aug 2011 | A1 |
Number | Date | Country |
---|---|---|
2625983 | Dec 1977 | DE |
3026513 | Jan 1982 | DE |
3807542 | Sep 1989 | DE |
294 207 | Sep 1991 | DE |
19649143 | Jun 1997 | DE |
102 16 538 | Jul 2003 | DE |
2 450 879 | Jan 2009 | GB |
2 457 578 | Aug 2009 | GB |
63-186507 | Nov 1988 | JP |
3-87506 | Sep 1991 | JP |
2003-25120 | Jan 2003 | JP |
2003-025120 | Jan 2003 | JP |
Entry |
---|
European Search Report, for Application No. 12182803.2 , dated Dec. 7, 2012. |
Number | Date | Country | |
---|---|---|---|
20130071193 A1 | Mar 2013 | US |