The invention addresses cutting tools used to create flat face/planar surfaces on workpieces. Tools used to do this are referred to as face milling tools. A face milling tool, or face mill, has one or, more generally, multiple cutting teeth around its circumference, often but not necessarily equally spaced, and positioned as desired in both the axial and radial dimensions. In many cases it is desired for all cutting teeth to be positioned such that they have the same axial positions and the same radial positions, though there are some cases where it may be desired to have specific axial and/or radial positioning of each tooth such that each is not the same as all the others.
A face mill is operated by attaching it to the spindle of a machine tool. The spindle then rotates to produce a cutting motion at a relatively high cutting speed (surface speed, or tangential speed) while the machine provides a feeding motion of the workpiece and/or the face mill, relative to the other, that occurs predominantly in the plane to which the spindle axis is perpendicular. The face mill removes a layer of material from the workpiece to create, with the tips of the cutting teeth, a new surface on the workpiece that is substantially parallel to the plane of the feeding motion.
Modern face mills are usually the “indexable” type. Such face mills are comprised of a cutter body that supports one, or often more than one, indexable cutting inserts. Cutting inserts generally have a cross-section of a particular shape, such as but not limited to triangular, square, rhombic, pentagonal, hexagonal, octagonal and circular/round, and having a thickness in the dimension generally perpendicular to the plane in which their cross-sectional shape is defined. Their size is generally set by the diameter of the inscribed circle, that is, the largest circle in the same plane of their noted shape, falling within all the edges and to which all or some the edges of the polygonal shape are tangent (or the diameter of the insert for round inserts). Cutting inserts are made of materials that are hard at room temperature, and retain their hardness at the elevated temperatures experienced during metal cutting. A cutting insert has multiple corners or edges; at a given time one corner/edge is used on each cutting insert affixed to the face mill body to perform material removal. These face mills are called “indexable” since the one or more cutting inserts can be indexed from one corner/edge to a new corner/edge when the corner/edge currently in use reaches a wear level at which it is considered consumed, and ultimately a fully used cutting insert can then be replaced with a new/fresh cutting insert and the corner/edge-to-corner/edge indexing cycle is repeated.
Cutter bodies support cutting inserts either directly or indirectly. Direct support, as shown in
It is often desirable to attach as many cutting inserts to a cutter body as possible to allow the greatest productivity when using the face mill. This is often limited by the manufacturability of the insert pockets or mounting module pockets. As shown in
a,
1
b and 2 show cutting inserts in a radial mounting. One way to allow more cutting inserts to be fit on a cutter body is to cut the insert pocket with tools accessing from the radial direction (or in a direction lying in a plane substantially parallel to the cutter-body radial-axial plane) and using a different type of insert clamp, such as a screw and wedge; an example is shown in
This leads to another consideration, that is, the cost to manufacture a face mill. Besides the noted excess material that must be removed for tool access in manufacture, machining the insert pocket or mounting module pocket often requires small tools with long overhangs and at complex angles. The complex angles often require (for modern competitiveness and accuracy) more costly four- and five-axis machines. The small tools with long overhangs require lower productivity cutting conditions. All this adds to the cost of manufacture. Also associated with increasing cost of manufacture is holding tight tolerance on the large cutter body so that the multiple insert pockets, or mounting module pockets, exhibit low variation from their specified position, especially in the axial direction. In fact, some face mills are made to allow the end-user to adjust, in the field, the axial position of each cutting insert to achieve even better axial alignment than is cost effectively possible without the adjustment. The adjustment adds cost and complexity, but is deemed worthwhile, especially for tools used to produce a finishing cut on a surface where the surface finish needs to be very smooth. The total range of misalignment across all cutting inserts assembled on the face mill is called runout, and is measured as “total indicator reading” or TIR. So, axial TIR is the difference in axial position from the highest to lowest cutting insert; it is generally desired that this be zero, and in practice it is costly to achieve small values. When axial TIR gets larger, surface finish of the machined part is degraded. Radial TIR can also have a negative effect on surface finish and overall performance of the face mill, but that effect is generally secondary to the negative effect of axial TIR on surface finish.
The present invention aims to allow higher tooth count per unit cutting diameter, especially when large inserts are used, and in a way that allows efficient manufacture using generally larger tools with less overhang and on a three-axis machine (generally lower-cost than four- and five-axis machines of comparable size), while also allowing ease of achieving low variation in axial position of multiple cutting inserts by way of adjustability either during the face mill manufacturing process or by way of adjustment in the field by the end-user.
This invention relates to face milling tools used to create a generally planar/face surface on a workpiece. Embodiments of this invention allow more teeth per unit tool diameter for certain types of cutting insert mounting styles and generally for larger cutting inserts. In particular, this invention allows the aforementioned while keeping manufacturing cost lower than it could be with some other designs, mainly by allowing manufacture of the insert mounting provisions on the face mill using larger tools that approach the face mill from mainly or exclusively the axial direction, thus requiring the equipment used to manufacture the cutter body to be a lower cost three-axis machine as compared to four- and five-axis machines that may be otherwise needed. Embodiments of the invention also permit adjustment of the axial positions of multiple cutting inserts and their support pockets by way of adjustment in the face mill manufacturing process. Other embodiments allow the adjustment to be made by the end-user in the field on a case-by-case basis after manufacture of the face mill is complete.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
The present invention is a face mill cutter body that comprises a body base 1 that is circular or regular polygonal about cutter axis 2 and one or more insert support pillars 3, as shown in
An insert support pillar 3 has at its pillar top 14 the appropriate geometry for either direct or indirect mounting of a cutting insert 15.
In this embodiment, adjustability is achieved in assembly of the face mill as follows:
Step A: Insert an insert support pillar 3 into each pillar pocket 4.
Step B: Insert a pillar clamp 5 into each clamp pocket 7, such that it interfaces correctly with pillar clamp receiver 6 on the respective insert support pillar 3, and affix by tightening its pillar clamp screw 12 (or alternative fastening element type).
Step C: Fasten a gauge (i.e., having tight tolerance on size and shape) setting insert in insert pocket 16 of (or integrated into by way of an intermediate insert mounting component) each insert support pillar 3.
Step D: Measure and record the insert axial height 19 (see
Step E: Remove each pillar clamp screw 12, pillar clamp 5 and insert support pillar 3.
Step F: Grind pillar end surface 9 of each insert support pillar 3 removing from its pillar end surface 9 an amount of material equal to the difference in its recorded insert axial height 19 and its desired insert axial height.
Step G: Replace all insert pillars 2 in the same pillar pockets 4 in which they were originally assembled, insert a pillar clamp 5, and affix by tightening its pillar clamp screw 12.
Note that Step C may be done earlier in the sequence and some steps can be performed on one pillar at a time.
Another embodiment is shown in
In another embodiment (see
The method of assembly and adjustment for this embodiment is as follows:
Step A: Insert adjustment screw 31 through adjustment hole 33.
Step B: Place adjustment spring 34 over/around adjustment screw 31 such that adjustment screw 31 passes through the inner diameter of adjustment spring 34.
Step C: Fill pillar pocket 4 with filler material 36 up to just below the top of adjustment spring 34.
Step D: Lower insert support pillar 3 onto adjustment screw 31 so that adjustment screw 31 inserts into adjustment screw hole 35 through pillar end surface 9 of pillar bottom 8.
Step E: Screw adjustment screw 31 into insert support pillar 3 until adjustment spring 34 is slightly compressed, some of filler material 36 has squeezed out, and assuring that pillar clamp receiver 6 is aligned with pillar clamp 5.
Step F: Lightly press pillar clamp 5 into clamp pocket 7 but do not tighten pillar clamp screw 12 more than gentle hand/finger tightness.
Step G: Fasten a gauge (i.e., having tight tolerance on size and shape) setting insert in insert pocket 16 of (or integrated into by way of an intermediate insert mounting component) each insert support pillar 3.
Step H: Tighten adjustment screw 31 until the gauge setting insert exhibits the desired insert axial height 19.
Step I: Repeat Steps A-H for each tooth location.
Step J: Wait for filler material 36 to solidify.
Step H: Affix each insert support pillar 3 by tightening its associated pillar clamp screw 12.
Note that Step G may be done earlier in the sequence and some steps can be performed on one pillar at a time.
The final embodiment allows an end-user to adjust each cutting insert 15 (not shown) in the field, after the face mill is fully manufactured. This embodiment (see
The first main difference is that there is a pillar clamp spring 41 that acts in compression between the head of pillar clamp screw 12 and a pillar clamp recess 42 in pillar clamp 5. Pillar clamp spring 41 allows pillar clamp screw 12 to be loosened slightly in order to make an adjustment in insert axial height 19 while still having a substantive force, that of pillar clamp spring 41 in its compressed state, forcing pillar end surface 9 downward against pocket bottom 10 and back against pillar pocket back-wall 11. After the adjustment step is completed, pillar clamp screw 12 is retightened to lock pillar clamp 5 and, thus, insert support pillar 3 in place for use of the face mill. Some applications may include one or more pillar clamp washers 43 (including one or more flat washers and possibly a lock washer) between the top of pillar clamp spring 41 and the head of pillar clamp screw 12 so as to increase the effective diameter of pillar clamp screw 12 to be large enough (that is, larger diameter than pillar clamp recess 42) to contact, through said pillar clamp washers 43, with the top of pillar clamp 5 when tightened.
The second main difference is that pillar spacer 21 of the previous embodiments is replaced with pillar adjustment wedge 44. Pillar adjustment wedge 44 has a pillar support surface 45 that is at a wedge angle 46 relative to being parallel to adjustment wedge bottom 47. Wedge angle 46 is generally, without limitation, in the range of 1 to 17 degrees. A larger wedge angle 46 will provide a larger range of axial height adjustment, but also generally reduces the resolution of adjustment actuation. Pillar end surface 9 of pillar bottom 10 includes a wedge interface surface 48 at substantially the same (opposing) wedge angle 46 so that it mates with pillar support surface 45. As pillar adjustment wedge 44 translates back and forth along pocket bottom 10, generally in a plane to which cutter axis 2 is normal, insert support pillar 3 moves up and down.
Translation of pillar adjustment wedge 44 along pocket bottom 10 is caused by turning adjustment screw 31 that passes through adjustment hole 33 in the side of insert support pillar 3. This adjustment requires that adjustment screw 31 cannot move along its screw axis 49. This is achieved with either screw head retainer 50 or screw end retainer 51; one or the other is necessary though both may be used if desired. Both screw head retainer 50 and screw end retainer 51 also serve to seal with their mating surfaces on the outside of insert support pillar 3 to keep particles of debris, and most of the liquid that may spray on the face mill, from entering into adjustment cavity 52 that would otherwise contaminate the components contained therein. Translation of pillar adjustment wedge 44, upon turning adjustment screw 31, occurs by way of the threaded interface between adjustment screw 31 and adjustment screw hole 35 in pillar adjustment wedge 44. An adjustment spring 34 may be included, as shown in
Finally, in this final embodiment, one would generally include a pillar seal 55 located in seal gland 56 in the outer surface of insert support pillar 3 at pillar bottom 8. This seal may be, for example, an O-ring. Pillar seal 55 serves to keep particles of debris and most of the liquid that may spray on the face mill from entering into pillar pocket 4 and ultimately contaminating adjustment cavity 52.
The method of assembly and adjustment for this embodiment is as follows:
Step A: Insert adjustment spring 34 (if used) into adjustment spring hole 54 in adjustment pillar wedge 44, and then adjustment pillar wedge 44 into adjustment cavity 52 of insert support pillar 3, which requires some compression of adjustment spring 34.
Step B: Insert adjustment screw 31 through adjustment hole 33 in insert support pillar 3 and thread into adjustment screw hole 35 until the head of adjustment screw 31 mates with the outside of insert support pillar 3.
Step C: Install screw head retainer 50 and screw end retainer 51 (if used), the latter being mated against the outside of insert support pillar 3 tight enough such that adjustment screw 31 cannot translate along screw axis 49.
Step D: Install pillar seal 55 into seal gland 56.
Step E: Insert an assembly from Step D into each pillar pocket 4.
Step F: Insert a pillar clamp 5 into each clamp pocket 7, such that it interfaces correctly with pillar clamp receiver 6 on the respective insert support pillar 3.
Step G: Insert a pillar clamp spring 41 into pillar clamp recess 42 on each pillar clamp 5.
Step H: Insert a pillar clamp screw 12 through each pillar clamp spring 41.
Step I: For each pillar clamp 5, compress pillar clamp spring 41 with the head (possibly with a one or more flat washers 43 and possibly a lock washer 43 under it) of pillar clamp screw 12 until pillar clamp screw 12 enters the mating threads on body base 1 and can be tightened.
Step J: Tighten each pillar clamp screw 12.
Step K: Fasten a gauge (i.e., having tight tolerance on size and shape) setting insert in insert pocket 16 of (or integrated into by way of an intermediate insert mounting component) each insert support pillar 3.
Step L: Loosen each pillar clamp screw 12 an axial distance equal to the range of axial adjustment possible for the given wedge angle 46.
Step M: Turn each adjustment screw 31 until each gauge setting insert is at its desired insert axial height 19.
Step N: Tighten each pillar clamp screw 12.
Field adjustment is performed by repeating Steps L through N, as needed, generally using actual cutting inserts 15 that are used for machining by the end-user rather than gauge setting inserts that are used generally at the manufacturer.
Note that Step K may be done earlier in the sequence and some steps can be performed on one pillar at a time.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
This application is based upon and claims priority to U.S. Provisional Application Ser. No. 62/181,765 filed Jun. 19, 2015, the disclosures of which are hereby incorporated in their entirety by reference herein.
Number | Date | Country | |
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62181765 | Jun 2015 | US |