Milling tool and coolant sleeve for milling tool

Abstract

The milling tool (100) has a shank portion and a head portion extending from the shank portion, an inner head surface of the head portion formed with a circumferentially extending head coolant obstruction formation (140) comprising a head ridge extending rearwardly from an adjacent head portion of the inner head surface, the adjacent head portion being located radially inwardly from the head ridge.

Description

[Technical field]

[0001] The subject matter of the present application relates to a tool assembly including a milling tool, a coolant sleeve (hereinafter also referred to as a "sleeve" for brevity) that surrounds a shank of the milling tool and is configured to supply coolant to the milling tool, and the milling tool. [Background technology]

[0002] The milling tool of the present invention was developed as an improvement over existing milling tools for manufacturing optical lenses.

[0003] Such existing optical lens milling tools operate at extremely high rotational speeds (e.g., but not limited to, 35,000 RPM). Existing optical lens milling tools typically have cutting elements of ultra-hard material, e.g., PCD or CBN, brazed into the cutting element recesses. In general, the designation "ultra-hard material" is intended to exclude common materials used in cutting inserts, such as "hard metals." However, while the preferred embodiment uses brazed ultra-hard cutting elements (for the applications described above), the present invention may in practice use hard metal materials, and replaceable indexable cutting inserts.

[0004] Furthermore, machining centers for optical lens manufacturing are not known to have high pressure coolants as is more common in metal shops and factories.

[0005] Some of the aspects of the invention below relate to tools with even a single cutting element (brazed or replaceable), so the phrase "cutting element" or "at least one cutting element" is used, although it should be understood that multiple cutting elements are typically preferred in milling applications. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the existing situation as described above, it is an object of the present application to provide a new and improved milling tool and other components of an assembly comprising such a milling tool.

[0007] It should be understood that while the particular features developed have been particularly beneficial for the optical lens milling application described above, it is envisioned that different milling tools and assemblies comprising the milling tools may also be improved using features or aspects of the present invention. [Means for solving the problem]

[0008] The present invention was developed to find a way to provide coolant to increase the tool life of the cutting elements of the milling tools described above.

[0009] Such development has been complicated by the high rotational speeds involved and the extraordinary demand for large amounts of coolant by the carbide cutting elements, especially PCD, which do not benefit as much from coolant as non-carbide materials (especially when heat transfer is divided among multiple cutting elements).

[0010] In accordance with one aspect of the present invention, a coolant sleeve has been developed that remains static (connected to a standard machining interface, not shown) relative to the rotary cutting tool.

[0011] In accordance with another aspect of the invention, the sleeve does not contact the milling tool, but is in close proximity to the head portion of the milling tool to ensure that coolant (not shown) enters the head coolant passages of the milling tool (to reach the cutting elements) and does not excessively exit the gap (i.e., the slight "separation distance") between the milling tool and the sleeve.

[0012] It will be appreciated that this is not a simple task, as the high rotational speed of the milling tool will tend to cause the coolant to escape any gaps and may cause damage or danger if the milling tool suddenly contacts the static sleeve. Such unintended contact may be caused by vibrations, cutting forces, etc.

[0013] In accordance with yet another aspect of the present invention, it is contemplated to provide the milling tool with a head coolant obstruction configuration (or "head labyrinth"), which may further reduce unintentional loss of coolant through the gap between the sleeve and the milling tool.

[0014] In accordance with yet another aspect of the present invention, it is contemplated to provide the milling tool with a shank coolant obstruction configuration (or "shank labyrinth"), which may further reduce unintentional loss of coolant through the gap between the sleeve and the milling tool.

[0015] In accordance with yet another aspect of the present invention, it is contemplated to provide the milling tool with a sleeve coolant obstruction configuration (or "sleeve labyrinth"), which may further reduce unintentional loss of coolant through the gap between the sleeve and the milling tool.

[0016] It will be appreciated that the separation distance and coolant obstruction configuration features described above each individually contribute to the intended purpose of assisting the coolant to reach its intended location, and thus a milling tool, sleeve or tool assembly according to the present invention may have any one or any combination of the above features.

[0017] Finally, due to the inherent high rotational speeds, it has been discovered that directing the coolant to the desired portion of the cutting element (in these embodiments, the desired portion is the main cutting edge of the cutting element) is ineffective because centrifugal forces redirect the coolant away from the desired portion.

[0018] Therefore, in accordance with yet another aspect of the present invention, it has been discovered that it is beneficial to redirect the coolant away from the midpoint of the main cutting edge in anticipation of the high rotational speeds of the milling tool resulting in a modification of the coolant direction.

[0019] Similarly, it should be understood that the above features of coolant directing are believed to be independent of the coolant obstruction configuration and separation distance, but that a milling tool having one or more of the above features would be beneficial.

[0020] Next, the above embodiment will be described in more detail.

[0021] According to one aspect of the invention, there is provided a milling tool comprising a shank portion and a head portion extending from the shank portion, a rotation axis extending along the shank portion and defining a forward direction from the shank portion towards the head portion, a rearward direction opposite the forward direction, a radially outward direction perpendicular to the forward and rearward directions and directed outward from the rotation axis, a radially inward direction opposite the radially outward direction, a rotational direction, and a counter-rotational direction opposite the rotational direction, the shank portion comprising a shank rearward end, a shank front end located closer to the head portion than the shank rearward end, and a shank outer surface, the head portion comprising a head outer surface, a head inner surface located closer to the shank portion than the head outer surface, a head coolant inlet opening at the head inner surface, and a head coolant outlet opening at the head outer surface, the coolant passages include a linear portion extending from a head coolant inlet to a head coolant outlet, the linear portion defining a passage plane, the passage plane extending adjacent to and parallel to the head coolant outlet, the head exterior surface including a plurality of alternating flutes and cutting portions, each cutting portion recessed in a counter-rotational direction and further including a cutting element recess having a center point and a center plane, the center plane satisfying at least one of the following conditions: the center plane includes the center point CP, the center plane extends at an angle of 45° between a forward direction and a radially outward direction (also referred to as the center plane angle μ), and each cutting portion further includes a cutting element assembled to the cutting recess, the cutting element including a major cutting edge having a midpoint, the center plane includes the midpoint, and the passage plane is directed forward relative to toward the center plane such that the passage plane forms an eccentric angle β with the center plane.

[0022] It should be appreciated that the concept of the present invention is to take into account the redirection that the significantly higher rotational speeds cause to the coolant flow, directing the coolant away from the desired area to be cooled. Thus, the various definitions above take into account the various differently designed tools that may be improved by this feature.

[0023] Below are some aspects that result in features designed to reduce coolant losses due to high rotational speeds.

[0024] According to one aspect of the invention, there is provided a milling tool comprising a shank portion and a head portion extending from the shank portion, wherein an axis of rotation extends along the head portion and defines a forward direction from the shank portion towards the head portion, a rearward direction opposite the forward direction, a radially outward direction perpendicular to the forward and rearward directions and directed outward from the axis of rotation, a radially inward direction opposite the radially outward direction, a rotational direction, and a counter-rotational direction opposite the rotational direction, wherein the shank portion comprises a shank rearward end, a shank frontward end located closer to the head portion than the shank rearward end, and a shank outer surface, wherein the head portion defines a head the head outer surface has a plurality of alternating longitudinal grooves and cutting portions, each cutting portion having a cutting element recess; the head inner surface is formed with an outer circumferentially extending head coolant obstruction configuration, the outer circumferentially extending head coolant obstruction configuration having a head ridge, the head ridge extending rearward from an adjacent head portion of the head inner surface, the adjacent head portion being located radially inward of the head ridge;

[0025] According to one aspect of the invention, there is provided a milling tool comprising a shank portion and a head portion extending from the shank portion, wherein a rotation axis extends along the head portion and defines a forward direction from the shank portion towards the head portion, a rearward direction opposite the forward direction, a radially outward direction perpendicular to the forward and rearward directions and directed outward from the rotation axis, a radially inward direction opposite the radially outward direction, a rotational direction, and a counter-rotational direction opposite the rotational direction, wherein the shank portion comprises a shank rearward end, a shank frontward end located closer to the head portion than the shank rearward end, and a shank outer surface, wherein the head portion defines a head portion having a head portion extending from the head portion toward the head portion, a rearward direction opposite the forward direction, a radially outward direction perpendicular to the forward and rearward directions and directed outward from the rotational axis, a radially inward direction opposite the radially outward direction, a rotational direction, and a counter-rotational direction opposite the rotational direction, the shank has an outer shank surface, a head inner surface located closer to the shank portion than the head outer surface, a head coolant inlet opening into the inner head surface, a head coolant outlet opening into the head outer surface, and a head coolant passage extending from the head coolant inlet to the head coolant outlet, the head outer surface having a plurality of alternating longitudinal grooves and cut portions, and at a shank rear end, the shank outer surface is formed with an outer circumferentially extending shank coolant obstruction configuration, the outer circumferentially extending shank coolant obstruction configuration having a shank ridge extending radially outwardly from an adjacent shank portion of the shank outer surface, the adjacent shank portion being located forward of the shank ridge.

[0026] According to one aspect of the invention, a coolant sleeve is provided, the coolant sleeve having a basic cylindrical shape and including a machine end with a connecting arrangement, a lower end opposite the machine end, a sleeve outer surface connecting the machine end and the lower end, a sleeve inner surface connecting the machine end and the lower end and located closer to a shank portion than the sleeve outer surface, a sleeve coolant inlet opening at the sleeve outer surface, a sleeve coolant outlet opening at the sleeve inner surface, and a sleeve coolant passage extending from the sleeve coolant inlet to the sleeve coolant outlet, the sleeve axis defining a forward direction from the machine end toward the lower end, a rearward direction opposite the forward direction, a radially outward direction perpendicular to the forward and rearward directions and directed outward from the sleeve axis, and a radially inward direction opposite the radially outward direction, the lower end being formed with an outer circumferentially extending sleeve coolant obstruction arrangement, the outer circumferentially extending sleeve coolant obstruction arrangement including a sleeve ridge extending forward of an adjacent sleeve portion of the lower end, the adjacent sleeve portion being located radially inward of the sleeve ridge.

[0027] According to one aspect of the invention, there is provided a tool assembly comprising a milling tool according to any one of the previous aspects, a sleeve, and a cutting element assembled to the milling tool.

[0028] According to one aspect of the invention, a tool assembly is provided, comprising a milling tool, a sleeve according to the above aspect, and a cutting element assembled to the milling tool.

[0029] According to one aspect of the present invention, a tool assembly is provided, the tool assembly comprising a milling tool, a sleeve, and a cutting element. The milling tool comprises a shank portion and a head portion extending from the shank portion. The rotation axis extends along the shank portion and is in the forward direction from the shank portion towards the head portion, the rear direction opposite to the forward direction, the radially outer direction orthogonal to the forward and rear directions and directed outward from the rotation axis, the radially inner direction opposite to the radially outer direction, the rotation direction, and the reverse rotation direction opposite to the rotation direction. The shank portion comprises a shank rear end portion, a shank front end portion positioned closer to the head portion than the shank rear end portion, and a shank outer surface. The head portion comprises a head outer surface, a head inner surface positioned closer to the shank portion than the head outer surface, a head coolant inlet opening into the head inner surface, a head coolant outlet opening into the head outer surface, and a head coolant passage extending from the head coolant inlet to the head coolant outlet and comprising a linear portion. The linear portion extends to the head coolant outlet and defines a passage plane which extends parallel adjacent to the head coolant outlet. The head outer surface comprises a plurality of alternating longitudinal grooves and cutting portions. The sleeve has a substantially cylindrical shape and a sleeve axis, and comprises a machine end portion having a connection configuration, a lower end portion opposite to the machine end portion, a sleeve outer surface connecting the machine end portion and the lower end portion, a sleeve inner surface connecting the machine end portion and the lower end portion and positioned closer to the shank portion than the sleeve outer surface, a sleeve coolant inlet opening into the sleeve outer surface, a sleeve coolant outlet opening into the sleeve inner surface, and a sleeve coolant passage extending from the sleeve coolant inlet to the sleeve coolant outlet. The sleeve surrounds the shank portion and is spaced apart from the shank portion. The lower end portion of the sleeve is adjacent to the head inner surface and is spaced apart from the head inner surface by a separation distance SD, and the separation distance SD satisfies the condition: 0.00 mm < SD < 1.00 mm.

[0030] According to any one of the above aspects, the following are preferred features: a. The head exterior surface may have a center plane. More precisely, each cutting element recess may have a center plane. The center plane may include a center point of the cutting element recess. The center plane may also or alternatively extend between the forward direction and the radially outward direction at an angle of 45°. The center plane may also or alternatively include a midpoint of the cutting element. b. The head coolant passage may include a linear portion extending to the head coolant outlet. The linear portion may define a passage plane extending adjacent to and parallel to the head coolant outlet, the passage plane being oriented in a forward direction rather than toward the central plane such that the passage plane forms an eccentric angle β with the central plane. c) The passage plane may be oriented in a more forward direction toward the central plane such that the passage plane forms an eccentric angle β with the central plane. The eccentric angle β may satisfy the condition: 5°<β<40°, preferably 10°<β<30°, and most preferably 15°<β<25°. d. At the shank aft end, the shank exterior surface is formed with a circumferentially extending shank coolant obstruction formation comprising a shank ridge that extends radially outwardly from an adjacent shank portion of the shank exterior surface that is forwardly disposed from the shank ridge (i.e., the adjacent shank portion is forwardly disposed from the shank ridge). The shank ridge may be shaped as an annular lip, preferably a circular annular lip. e. The shank coolant obstruction configuration may include an additional shank ridge extending radially outwardly (i.e. extending radially outwardly) from and forwardly (i.e. located forwardly of) the adjacent shank portion, and the additional shank ridge may be shaped as an annular lip, preferably a circular annular lip. f. The head inner surface may be formed with a circumferentially extending head coolant obstruction configuration comprising a head ridge extending aft from an adjacent head portion of the head inner surface, the adjacent head portion being located radially inward from the head ridge. The head ridge may be shaped as an annular lip, preferably a circular annular lip. g. The head coolant obstruction configuration may include a further head bulge, which extends rearward (i.e., behind the adjacent head portion) from the adjacent head portion and is located in the radially inward direction from the adjacent head portion (i.e., radially inward of the adjacent head portion). The further head bulge may be shaped as an annular lip, preferably a circular annular lip. h. The head coolant outlet may be elongated in the forward and rearward directions. Preferably, the coolant outlet is elongated in the same direction as the adjacent rake face of the cutting element for better coolant of the cutting element. Even more preferably, the coolant outlet is elongated in the same direction as the cutting element height of the cutting element (when the cutting element is not circular), and the cutting element height is the maximum dimension of the cutting element parallel to the rake face of the cutting element. i. It will be understood that the milling tool according to the present invention may include a plurality of head coolant outlets for each longitudinal groove (since the head coolant outlet opens into the longitudinal groove), or (if desired to be defined as such) a plurality of head coolant outlets for each cutting portion, but preferably there is only a single elongated outlet for each longitudinal groove or cutting portion. This is preferred because at high rotational speeds, the conventional circular outlet holes, which are the easiest to manufacture by conventional drilling methods, do not provide optimal dispersion of the coolant along the cutting element. That being said, it is possible for the milling tool according to the present invention to include a plurality of head coolant outlets that also have a conventional circular cross-sectional shape for each longitudinal groove or cutting portion. j. The head coolant outlet is preferably elliptical in shape. Such a shape is more difficult to manufacture than a circular cross-section, but has been found to provide better dispersion of the coolant along the cutting element at high rotational speeds. k. The head coolant outlet may have a head coolant outlet height HO, the cutting element directly adjacent to the head coolant outlet may have a cutting element height HC, and the head coolant outlet height HO and the cutting element height HC may satisfy the condition: 0.1HC < HO < HC, preferably, 0.2HC < HO < 0.8HC, most preferably, 0.3HC < HO < 0.5HC. Advantageously, a single relatively small head coolant outlet may result in an acceleration of the coolant flow for effective cooling. l. The head coolant outlet may be closer to the cutting element recess than any other adjacent surface of the cutting portion. Stated differently, in a direction facing the head coolant outlet, the head coolant outlet may be located directly adjacent to the cutting element. Alternatively defined, in a direction facing the head coolant outlet, no gap is visible between the head coolant outlet and the cutting element. Alternatively defined, in a side view of the cutting element, the head coolant outlet is directly adjacent to the cutting element. Regardless of which of these definitions is used, it has been discovered that by keeping the head coolant outlet as close as possible to the cutting element, more coolant can reach the desired location on the cutting element. m. Preferably, there are at least 8 cutting portions, preferably there are at least 10 cutting portions. n. The milling tool may include at least one cutting element. More precisely, each cutting portion may include one cutting element. Each of the at least one cutting element may be directly adjacent to the head coolant outlet. Preferably, the at least one cutting element may be 6 or more cutting elements, more preferably 11 or more cutting elements. The head coolant outlet opening may comprise a plurality of head coolant outlet openings, and each one of the plurality of flutes may have at least one of the plurality of head coolant outlets opening into the flute. p. The milling tool may include a cutting element immediately adjacent the head coolant outlet, the cutting element recess having a center point and a center plane that includes the center point. q. The cutting element or elements may be made from an ultra-hard material, preferably PCD. r. The cutting element may include a main cutting edge. More specifically, the cutting element may often have a beveled edge, a wiper edge, etc. The main cutting edge is the primary, typically largest, cutting edge of the cutting element. It should be understood that in this application, the main cutting edge refers to the edge that is positioned for operation in embodiments where an indexable cutting element is used with the milling tool of the present invention. The lower end of the sleeve can be formed with a sleeve coolant obstruction structure extending on the outer periphery, and the sleeve coolant obstruction structure extending on the outer periphery includes a sleeve ridge extending forward from the adjacent sleeve portion of the lower end, and the adjacent sleeve portion is located in the radially inner direction from the sleeve ridge. In other words, the further sleeve ridge extends in front of the adjacent sleeve portion, and the further adjacent sleeve ridge is located radially inward of the adjacent sleeve portion. The sleeve ridge can be formed as an annular lip, preferably a circular annular lip. t. The sleeve coolant obstruction structure can include a further sleeve ridge, the further sleeve ridge extends forward from the adjacent sleeve portion, and the further sleeve ridge is located in the radially inner direction from the adjacent sleeve portion. The further sleeve ridge can be formed as an annular lip, preferably a circular annular lip. u. The tool assembly can include a sleeve, the sleeve surrounds the shank portion of the milling tool and is spaced apart from the shank portion. The lower end of the sleeve can be adjacent to the inner surface of the head and is spaced apart from the inner surface of the head by a separation distance SD, and the separation distance SD satisfies the condition: 0.00 mm < SD < 1.00 mm. Preferably, the separation distance SD satisfies the condition: SD < 0.60 mm, preferably SD < 0.45 mm, most preferably SD < 0.30 mm. Preferably, the separation distance SD satisfies the condition: SD > 0.05 mm, preferably SD > 0.10 mm, most preferably SD > 0.15 mm. v. The sleeve can include a plurality of coolant inlets. This has been found to be advantageous for the present invention which is typically designed for a machining center equipped with only a low-pressure pump (i.e., a pump that supplies 60 liters per minute of coolant at 6 bar). Further, the plurality of coolant inlets enable a larger amount of coolant to enter the sleeve without an overly large inlet cross-section. Nevertheless, the present invention is considered to be feasible also for high-pressure coolant supply.

[0031] To better understand the subject matter of the present application and to show how the present application can be actually implemented, reference is now made to the accompanying drawings.

Brief Description of the Drawings

[0032] [Figure 1A] FIG. 1 is a perspective view of a tool assembly according to the present application. [Figure 1B] FIG. 1B is a perspective side view of the tool assembly of FIG. 1A showing the schematic coolant flow exiting the tool assembly, illustrating the exit direction of the flow when the coolant flow is not affected by centrifugal force. [Figure 1C] FIG. 1B is an exploded side view of the tool assembly of FIG. 1A. [Figure 2A] FIG. 1B is a perspective view of a milling tool of the tool assembly of FIG. 1A. [Figure 2B] FIG. 2B is a top view of the milling tool of FIG. 2A. [Figure 2C] FIG. 2B is a side view of the milling tool of FIG. 2A. [Figure 2D] FIG. 2B is a bottom view of the milling tool of FIG. 2A. [Figure 3A] FIG. 1B is a perspective view of a sleeve of the tool assembly of FIG. 1A. [Figure 3B] FIG. 3B is a top view of the sleeve of FIG. 3A. [Figure 3C] FIG. 3B is a side view of the sleeve of FIG. 3A. [Figure 3D] FIG. 3B is a bottom view of the sleeve of FIG. 3A. [Figure 3E] FIG. 3C is another top view of the same sleeve shown in FIG. 3B. [Figure 3F] FIG. 3F is a cross-sectional view taken along line IIIF-IIIF of FIG. 3E. [Figure 4A] FIG. 2 is a perspective view of the tool assembly of FIG. 1 with one direction facing the milling tool head coolant outlet and a schematic coolant flow path exiting the tool assembly shown, illustrating the exit direction of flow when affected by centrifugal force. [Figure 4B] FIG. 4B is an enlarged view of the boxed area designated by X in FIG. 4A. [Figure 4C] FIG. 1B is a cross-sectional view of the tool assembly of FIG. [Diagram 5] 1 is a cross-sectional view of another embodiment of a milling tool according to the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] 1A-1C, an example tool assembly 10 is shown comprising a milling tool 100 and a sleeve 200 that surrounds a portion of the milling tool 100 and is configured to be static relative to the milling tool 100 when the milling tool 100 is rotating.

[0034] The milling tool 100 (or alternatively defined, the tool assembly 100) comprises at least one cutting element 300 assembled to the milling tool.

[0035] The cutting elements 300 have a flat rake face 306 and a base face 308 (FIG. 4B) connected by a peripheral edge 310, the flat rake face 306 and the base face 308 having a basic semicircular shape. The cutting elements 300 are made from sintered diamond (PCD), and there are twelve cutting elements 300 in this example.

[0036] Each cutting element 300 preferably includes an arc-shaped major cutting edge 302 that extends approximately 180° and includes a midpoint 304 .

[0037] In FIG. 4B, the assembled cutting element 300 is shown to have a cutting element height HC measured parallel to the direction of elongation of the adjacent head coolant outlets 134.

[0038] 2A-2D, milling tool 100 includes a shank portion 102 and a head portion 104 extending from shank portion 102. As shown in FIG.

[0039] The rotation axis AR extends along the shank portion 102 and defines a forward direction DF1 from the shank portion 102 toward the head portion 104, a rearward direction DR1 opposite the forward direction DF1, a radially outward direction DO1 perpendicular to the forward direction DF1 and the rearward direction DR1 and directed outward from the rotation axis AR, a radially inward direction DI1 opposite the radially outward direction DO1, a rotation direction DX1, and a reverse rotation direction DY1 opposite the rotation direction DX1.

[0040] The shank portion 102 includes a shank rear end 106 , a shank front end 108 located closer to the head portion 104 than the shank rear end 106 , and a shank outer surface 110 .

[0041] At the shank aft end 106, the shank exterior surface 110 is formed with a circumferentially extending shank coolant obstruction formation 112 that includes a protruding shank ridge 114 that extends radially outwardly from an adjacent shank recessed portion 116 on the shank exterior surface that is forward of the shank ridge 114. The shank ridge 114 is shaped as a circular annular lip.

[0042] The shank coolant obstruction arrangement 112 also includes a further protruding shank ridge 118 that is located forward of the shank recessed portion 116 and is shaped as a circular annular lip.

[0043] In embodiments with both the shank ridge 114 and the further shank ridge 118, the adjacent shank recess 116 may be considered an annular groove.

[0044] A first further annular groove 120 is shown rearward of the shank ridge 114 and forward of another portion 122 of the shank outer surface 110 .

[0045] A second further annular groove 124 is shown forward of the further shank ridge 118 and rearward of yet another portion 126 of the shank outer surface 110 .

[0046] The head portion 104 includes an outer head surface 128, an inner head surface 130 located closer to the shank portion 102 than the outer head surface 128, a head coolant inlet 132 opening into the inner head surface 130, and a head coolant outlet 134 opening into the outer head surface 128.

[0047] The head exterior surface 128 includes a plurality of alternating flutes 136 and cutting portions 138 .

[0048] The head inner surface 130 is further formed with a circumferentially extending head coolant obstruction formation 140 .

[0049] The head coolant obstruction arrangement 140 includes an upwardly projecting head ridge 142 that is shaped as a circular annular lip and extends in a rearward direction DR1 from an adjacent head portion 144 on the head inner surface that is located radially inward from the head ridge 142. The transition from the head ridge 142 to the adjacent head portion 144 may be considered a lower radially inward circumferential step.

[0050] The head coolant obstruction arrangement 140 further comprises a further head ridge 146 that is shaped as a circular annular lip and extends in a rearward direction DR1 from the adjacent head portion 144 and is located in a radially inward direction DI1 from the adjacent head portion 144. The transition from the adjacent head portion 144 to the further head ridge 146 may be considered an upper radially inner circumferential step.

[0051] In embodiments with both the head ridge 142 and the further head ridge 146, the adjacent head portion 144 may be considered an annular groove.

[0052] Further inward of the head coolant impeding arrangement 140 is a head reservoir 148 which serves to stabilize the coolant and then allow it to proceed into each head coolant inlet 132 .

[0053] 3A-3F, sleeve 200 has a basic cylindrical shape and comprises a machine (upper) end 202 with a connection arrangement 204, a lower end 206 opposite machine end 202, a sleeve outer surface 208 connecting machine end 202 and lower end 206, a sleeve inner surface 210 connecting machine end 202 and lower end 206 and positioned closer to shank portion 102 than sleeve outer surface 208, a sleeve coolant inlet 212 opening at sleeve outer surface 208, a sleeve coolant outlet 214 opening at sleeve inner surface 210, and a sleeve coolant passage 216 (FIG. 3F) extending from sleeve coolant inlet 212 to sleeve coolant outlet 214.

[0054] The connection arrangement 204 includes a plurality of circumferentially spaced threads 218 received within a recessed area 220 and extending through threaded holes 222 for fastening to a mechanical interface (not shown).

[0055] Due to the connection to a machine interface (not shown), the sleeve 200 remains static relative to the rotary milling tool 100 .

[0056] The sleeve 200 has a sleeve axis AS which may alternatively be defined in the same direction as the milling tool 100. Because the sleeve axis and the axis of rotation are coaxial, the directions defined with respect to the milling tool 100 will be used in describing the tool assembly 10 for convenience.

[0057] Thus, the sleeve axis AS defines a sleeve forward direction DF2 extending from the machine end 202 toward the lower end 206, a sleeve rearward direction DR2 opposite the sleeve forward direction DF2, a sleeve radially outer direction DO2 perpendicular to the forward direction DF2 and the rearward direction DR2 and directed outward from the sleeve axis AS, and a radially inner direction DI2 opposite the radially outer direction DO2.

[0058] The sleeve lower end 206 is formed with an outer circumferentially extending sleeve coolant obstruction arrangement 224 that includes a protruding sleeve ridge 226 that is shaped as a circular annular lip and extends forward of an adjacent sleeve recess 228 at the lower end 206 that is located radially inward from the sleeve ridge 226.

[0059] The sleeve coolant obstruction arrangement 224 may further comprise a further sleeve ridge 230 shaped as a circular annular lip and extending in the sleeve forward direction DF2 beyond the adjacent sleeve recessed portion 228 .

[0060] In embodiments with both the protruding sleeve ridge 226 and the further sleeve ridge 230, the adjacent sleeve recess 228 may be considered an annular groove.

[0061] With particular reference to FIGS. 3E and 3F, the inner surface 210 of the sleeve defines a chamber 232 .

[0062] The chamber 232 comprises a first (upper) sub-chamber 234 having a diameter slightly larger than the shank portion 102 (the first (upper) sub-chamber 234 defines a gap 240 therebetween, designated in FIG. 4C, although the gap is so small that it is not clearly visible, so the number 240 merely aids understanding), a second (middle) sub-chamber 236 having a slightly larger diameter than the first sub-chamber 234, and a third (lower) sub-chamber 238 having an even larger diameter than the second sub-chamber 236. The sleeve inner surface 210 tapers in the sleeve radially outward direction D02 as the sleeve inner surface 210 increases in the forward direction DF2. This allows the third sub-chamber 238 to be provided with a sleeve trough 242.

[0063] The sleeve reservoir 242 may be beneficial in stabilizing the coolant as it aids in the coolant's entry into each head coolant inlet 132 .

[0064] The sleeve 200 optionally includes connectors 244 (FIG. 1C) configured to attach to the sleeve coolant inlets 212 and supply tubes (not shown). In such case, the sleeve outer surface 208 is formed with a sleeve inlet recess 213 for each sleeve coolant inlet 212.

[0065] 4A and 4B, the head coolant outlet 134 is elongated in a forward direction DF1 and a rearward direction DF2 and is elliptical in shape.

[0066] More precisely, the head coolant outlet 134 has a head coolant outlet height HO and a head coolant outlet width HW that is smaller than the head coolant outlet height HO.

[0067] As shown, the head coolant outlet 134 is directly adjacent the cutting element 300. The head coolant outlet 134 is closer to the cutting element 300 than the flute center point FC. Alternatively defined, the head coolant outlet 134 is closer to the cutting element 300 than the adjacent surface 150 located in the rotational direction DX1 from the described cutting element 300.

[0068] 4C , the head coolant passage 152 extends from the head coolant inlet 132 to the head coolant outlet 134 and includes a linear portion 154 that extends to the head coolant outlet 134 and defines a passage plane PP that extends adjacent to and parallel to the head coolant outlet 134. In this embodiment, the entire head coolant passage 152 extends linearly or straight. However, it should be understood that only the portion of the head coolant passage 152 adjacent to the head coolant outlet 134 determines the direction of coolant flow exiting the head coolant passage 152.

[0069] The passage plane PP is oriented in a more forward direction toward the central plane such that the passage plane PP forms an eccentric angle β with the passage plane PP.

[0070] Each cutting portion 138 is recessed in a counter-rotational direction and further includes a cutting element recess 156 (FIG. 1C) having a center point CP (FIG. 1C; shown only diagrammatically on the cutting element for illustrative purposes in FIG. 4C), and a central plane PC that contains the center point CP.

[0071] In particular, coolant flow path FP is shown in FIG. 4C. Coolant (not shown) enters sleeve coolant passage 216 until it strikes shank portion 102 and enters second sub-chamber 236 (because the gap between shank portion 102 and sleeve 200 is designed smaller in first sub-chamber 234 and the coolant is redirected in rearward direction DF1 at first bend 158 toward head portion 104). Shank coolant obstruction feature 112 further assists in reducing coolant exiting in rearward direction DR1 by impeding the flow of coolant.

[0072] Following the first bend 158, the coolant reaches the (matching) head basin 148 and the sleeve basin 242 before entering the head coolant inlets 132. The sleeve coolant obstruction arrangement 140 and the head coolant obstruction arrangement 224 help reduce the coolant exiting in the radially outward direction DO1 and the rearward direction DR1.

[0073] After the coolant leaves the head coolant outlet 134, the coolant flow passage FP includes a second bend 160 caused by centrifugal force, thus directing the coolant toward the center point CP of the cutting element recess 156 along the central plane PC rather than its initial direction from the head coolant outlet 134 along the passage plane PP. In FIG. 1B, a schematic coolant flow 162 is shown, which is the direction of the coolant if it were not affected by centrifugal force (thus, the coolant flow 162 does not cool most of the cutting elements 300, although this is not the case due to the high rotational speed of the milling tool 100).

[0074] In particular, the sleeve lower end is adjacent to the inner surface of the head and is spaced from the head surface by a separation distance SD.

[0075] 5, another embodiment of a milling tool 1000 is shown, it being understood that the only significant difference is the head coolant passages and their shapes. In this example, there are three head coolant passages 1002, 1004, 1006 per flute or cut, each having a conventional circular cross section with a circular exit hole.

Claims

1. A coolant sleeve (200) having a basic cylindrical shape for surrounding a shank portion (102) of a milling tool (100), comprising: a machine end (202) having a connection arrangement (204); a lower end (206) opposite said machine end (202); an outer sleeve surface (208) connecting the machine end (202) and the lower end (206); an inner sleeve surface (210) connecting the machine end (202) and the lower end (206); a sleeve coolant inlet (212) opening to the sleeve outer surface (208); a sleeve coolant outlet (214) opening to the sleeve inner surface (210); a sleeve coolant passage (216) extending from the sleeve coolant inlet (212) to the sleeve coolant outlet (214); the sleeve axis (AS) defines a sleeve forward direction (DF2) from the machine end (202) toward the lower end (206), a sleeve rearward direction (DR2) opposite the sleeve forward direction (DF2), a sleeve radially outer direction (DO2) perpendicular to the sleeve forward direction (DF2) and the sleeve rearward direction (DR2) and directed outward from the sleeve axis (AS), and a sleeve radially inner direction (DI2) opposite the sleeve radially outer direction (DO2); the lower end (206) is formed with a circumferentially extending sleeve coolant obstruction arrangement (224); the sleeve coolant obstruction arrangement (224) includes a sleeve ridge (226) extending forward of an adjacent sleeve portion (228) of the lower end (206); the adjacent sleeve portion (228) is located radially inward of the sleeve ridge (226); The connection arrangement (204) is the only connection arrangement of the coolant sleeve (200).

2. the sleeve coolant obstruction arrangement (224) comprises a further sleeve ridge (230) extending forward of the adjacent sleeve portion (228); The coolant sleeve (200) of claim 1, wherein the further sleeve ridge (230) is located radially inward of the adjacent sleeve portion (228).

3. A milling tool (100) comprising a shank portion (102) and a head portion (104) extending from the shank portion (102); The coolant sleeve (200) of claim 1; at least one cutting element (300) assembled to said milling tool (100); The coolant sleeve (200) surrounds and is spaced from the shank portion (102).

4. The milling tool 100 further comprises an axis of rotation (AR), the rotation axis (AR) extends along the shank portion (102) and defines a forward direction (DF1) from the shank portion (102) to the head portion (104), a rearward direction (DR1) opposite to the forward direction (DF1), a radially outward direction (DO1) perpendicular to the forward direction (DF1) and the rearward direction (DR1) and directed outward from the rotation axis (AR), a radially inward direction (DI1) opposite to the radially outward direction (DO1), a rotation direction (DX1), and a counter-rotation direction (DY1) opposite to the rotation direction (DX1); The shank portion (102) has a shank rear end (106), a shank front end (108) located closer to the head portion (104) than the shank rear end (106), and a shank outer surface (110); the head portion (104) has a head outer surface (128), a head inner surface (130) located closer to the shank portion (102) than the head outer surface (128), a head coolant inlet (132) opening into the head inner surface (130), a head coolant outlet (134) opening into the head outer surface (128), and a head coolant passage (152) extending from the head coolant inlet (132) to the head coolant outlet (134), the head exterior surface (128) has a plurality of alternating flutes (136) and cutting portions (138); Each of said cutting portions (138) includes a cutting element recess (156); the head inner surface (130) is formed with a circumferentially extending head coolant obstruction configuration (140); the circumferentially extending head coolant obstruction configuration (140) comprises a head ridge (142) extending rearward of an adjacent head portion (144) of the head interior surface (130); The adjacent head portion (144) is located radially inward of the head protuberance (142), the sleeve lower end (206) is adjacent to the head inner surface (130) and spaced apart from the head inner surface (130) by a separation distance (SD); The tool assembly (10) of claim 3, wherein the separation distance (SD) satisfies the condition: 0.00 mm<SD<1.00 mm.

5. 5. The tool assembly (10) of claim 4, wherein the separation distance (SD) satisfies the condition 0.05 mm<SD<0.60 mm.

6. The tool assembly (10) of claim 4, wherein the head ridge (142) is shaped as an annular lip.

7. the head coolant obstruction arrangement (140) comprises a further head ridge (146); 5. The tool assembly (10) of claim 4, wherein the further head ridge (146) extends rearward of the adjacent head portion (144) and is located radially inward of the adjacent head portion (144).

8. The tool assembly (10) of claim 7, wherein the further head ridge (146) is shaped as an annular lip.

9. Nearer the shank rear end (106) than the shank front end (108), the shank outer surface (110) is formed with a circumferentially extending shank coolant obstruction configuration (112); the circumferentially extending shank coolant obstruction configuration (112) comprises a shank ridge (114) extending radially outward of an adjacent shank portion (116) of the shank outer surface (110); The tool assembly (10) of claim 4, wherein the adjacent shank portion (116) is located forward of the shank ridge (114).

10. The tool assembly (10) of claim 9, wherein the shank ridge (114) is shaped as an annular lip.

11. the shank coolant obstruction arrangement (112) comprises a further shank ridge (118); 10. The tool assembly (10) of claim 9, wherein the further shank ridge (118) extends radially outwardly of the adjacent shank portion (116) and is located forward of the adjacent shank portion (116).

12. the cutting element recess (156) has a center point (CP) and a center plane (PC) that includes the center point (CP); the head coolant passage (152) includes a linear portion (154) extending to the head coolant outlet (134); the linear portion (154) defines a passage plane (PP) extending parallel to and adjacent the head coolant outlet (134); 5. The tool assembly (10) of claim 4, wherein the passage plane (PP) is oriented in the forward direction (DF1) rather than towards the central plane (PC) such that the passage plane (PP) forms an eccentric angle β with the central plane (PC).

13. 13. The tool assembly (10) of claim 12, wherein the eccentric angle β satisfies the condition: 5°<β<40°.

14. The tool assembly (10) of claim 4, wherein the head coolant outlet (134) is elongated.

15. The head coolant outlet (134) is elongated in the direction of extension; a head coolant exit height (HO) measured parallel to the elongation direction; the milling tool (100) further comprising a cutting element (300) directly adjacent the head coolant outlet (134); the cutting element (300) has a cutting element height (HC) measured parallel to the direction of elongation; Condition: 0.1HC<HO<HC The tool assembly (10) of claim 14, wherein

16. The tool assembly (10) of claim 4, wherein the head coolant outlet (134) is closer to the cutting element recess (156) than any other adjacent surface of the cutting portion (138).

17. The tool assembly (10) of claim 16, wherein in a side view of the cutting element (300), the head coolant outlet (134) is directly adjacent the cutting element (300).

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