Cutting insert having a cooling channel feature

Abstract

The cutting insert includes a corner cutting region and a cooling channel formed within a wall cavity. The cutting insert includes a body having an upper insert surface, a lower insert surface defining a lower insert plane, and at least one side wall extending between them. The corner cutting region is defined between at least one side wall and the upper insert surface. The at least one side wall is formed together with at least one cooling channel formed within the wall cavity, the cooling channel defining a coolant flow path having an upstream section with a coolant inlet facing the lower insert plane. The coolant flow path further has a downstream section extending below the corner cutting region. The coolant flow path is at least partially exposed to the outside of the cutting insert and includes an arc-shaped portion between the upstream and downstream sections.

Description

Technical Field

[0001] The subject matter of the present disclosure generally relates to cutting tools and cutting inserts, and more particularly to cutting tools and cutting inserts having external cooling channels.

[0002] The approval of the above references in this specification should not be inferred to mean that they are relevant in any way to the patentability of the presently disclosed subject matter.

Background Art

[0003] During a cutting operation on a workpiece, it is well known in the art to direct a cooling fluid, i.e., a coolant, towards the cutting interface of the cutting tool. By directing the coolant towards the interface between the cutting tool and the workpiece, the cutting interface is cooled during the cutting operation, thereby preventing damage to both the cutting edge and the workpiece.

[0004] Generally, a cutting tool has a rake face and at least one flank or flange face, and at the intersection thereof, a cutting edge of the tool is defined. The cooling fluid is generally directed towards the interface from either the side of the rake face, or the side of the flank, or from a direction applying the coolant to both surfaces forming the cutting edge.

[0005] The cutting tool may also include a cutting insert that performs the actual machining or cutting operation on the workpiece surface. Such a cutting insert is associated with a cooling device separate from the cutting insert, and the cooling device is configured to supply coolant to the cutting insert from the outside.

[0006] A conventional cutting insert may have a cutting corner region defined between a first side surface, a second side surface, and one of the upper and lower surfaces. A cooling cavity including a cooling surface proximate to the cutting corner region is configured to receive therein a coolant for cooling the interface between the cutting insert and the workpiece, thereby drawing heat away from the cutting corner region.

[0007] Typically, the entire cutting corner area is covered with a coating to enhance durability. However, coatings can reduce the thermal conductivity of the cooling surface, thereby diminishing its effectiveness. Therefore, an objective of this disclosure is to increase the thermal conductivity of the cooling surface by not applying a coating material to the cooling surface that covers the rest of the cutting corner area. [Prior art documents] [Patent Documents]

[0008] The following is a list of references considered relevant to the background of the currently disclosed subject matter. -US Patent No. 9095913 (B2) -US Patent No. 9656323 (B2) - US release number 2021 / 0205895(A1) - International Publication No. 2023 / 079549(A1) [Overview of the Initiative]

[0009] Accordingly, a cutting insert according to an embodiment of the subject matter of the present disclosure is provided. The cutting insert according to the subject matter of the present disclosure comprises a body having an upper insert surface, a lower insert surface defining a lower insert plane, and at least one side wall extending between them. The cutting insert further comprises at least one corner cutting region defined between the at least one side wall and the upper insert surface.

[0010] In some embodiments, at least one side wall is formed with at least one cooling channel defining a coolant flow path extending between its upstream section having a coolant inlet facing the lower insert plane and its downstream section extending below the at least one corner cutting region. In some embodiments, the coolant flow path is at least partially exposed to the outside of the cutting insert and includes an arc-shaped portion between the upstream and downstream sections.

[0011] In some embodiments, the arcuate portion is characterized by a single smooth curve along at least a portion of the coolant flow path. In some embodiments, the single smooth curve extends along a planar dimension parallel to at least one side wall. In some embodiments, the arcuate portion generates pressure in the coolant guided along it, thereby increasing the coolant flow along the coolant flow path to increase heat removal in the corner cutting region. In some embodiments, the arcuate portion has a radius in three dimensions along at least a portion of it.

[0012] In some embodiments, the arc-shaped portion has a decreasing radius along at least one portion of the coolant flow path extending from the upstream section to the downstream section, corresponding to the increasing centrifugal force along that portion of the coolant flow path. In some embodiments, a single smooth curve has a decreasing radius in the dimension across the coolant flow path from the upstream section to the downstream section.

[0013] In some embodiments, the arc portion extends along the coolant channel over an arc length of at least 90 degrees. In some embodiments, the arc portion extends along the coolant channel over an arc length greater than 90 degrees. In some embodiments, the arc portion extends over an arc length in the range of 105 to 125 degrees. In some embodiments, the arc portion is configured to guide the coolant downward along the coolant channel in the corner cutting region to enhance heat removal therein.

[0014] In some embodiments, the cooling channel is formed within a wall cavity, at least a portion of which is exposed to the outside of the cutting insert. In some embodiments, the majority of the coolant flow path is exposed to the outside of the cutting insert. In some embodiments, the majority of the coolant flow path is exposed toward the downstream section, and a small portion of the coolant flow path is enclosed toward the upstream section. In some embodiments, the coolant flow path in the upstream section is enclosed toward the outside. In some embodiments, the coolant flow path thereby includes exposed and enclosed portions along it, which together form a combined coolant flow.

[0015] In some embodiments, the coolant flow path is gradually exposed from the upstream section toward the downstream section. In some embodiments, the outer wall portion surrounds the coolant inlet in the upstream section. In some embodiments, the outer wall portion slopes toward the arc portion and becomes smooth with the arc portion at a smooth transition point between the upstream and downstream sections. In some embodiments, the coolant inlet has an inlet radius. In some embodiments, the outer wall portion slopes toward the coolant inlet to increase the coolant flow path width relative to the inlet radius as the coolant is guided toward the downstream section along the coolant flow path.

[0016] In some embodiments, the cooling channel further comprises an arcuate bank portion extending along the arcuate portion, the arcuate bank section inclined from the arcuate portion toward the internal cavity surface of the wall cavity to guide the coolant along it. In some embodiments, the internal cavity surface is parallel to the coolant flow path. In some embodiments, the internal cavity surface extends parallel to the sidewall surface of the sidewall.

[0017] In some embodiments, the coolant inlet has an inlet diameter configured to receive coolant from a coolant outlet that is in fluid communication with the coolant inlet. In some embodiments, the coolant outlet has an outlet diameter corresponding to the inlet diameter. In some embodiments, the corner cutting region has a corner bank portion configured to redirect the coolant below the corner cutting region.

[0018] In some embodiments, the sidewall includes opposing sidewall portions that are angled toward each other. In some embodiments, the opposing sidewall portions together define a branched wall cavity below the corner cutting area. In some embodiments, the branched wall cavity comprises opposing cooling channels that are in fluid communication with each other. In some embodiments, the opposing cooling channels together define a branched cooling channel flow path, the opposing portions of which are angled toward each other and directed toward the corner cutting area.

[0019] In some embodiments, the insert central plane extends perpendicularly to the upper and lower insert surfaces. In some embodiments, the branch wall cavity is symmetrical with respect to the insert central plane. In some embodiments, opposing cooling channels formed within the branch wall cavity are symmetrical with respect to the insert central plane. In some embodiments, the corner cutting region has a rake face on the upper insert surface and a side surface on the side wall surface, thereby providing at least one cutting edge on the upper insert surface. In some embodiments, at least one cooling channel extends from the side surface to the lower insert surface.

[0020] In some embodiments, the corner cutting region comprises opposing cutting edges angled with respect to each other. In some embodiments, the corner cutting region comprises a curved cutting edge between the opposing cutting edges. In some embodiments, the corner cutting region comprises a tapered portion spaced from the curved cutting edge and above the corner bank portion. In some embodiments, the body is in the form of a rhombus having acute angles at the corner cutting region and the insert corner opposite the corner cutting region.

[0021] In some embodiments, the cooling channels are configured to face the workpiece during the cutting operation. In some embodiments, the workpiece includes an inner surface of the workpiece. In some embodiments, the cooling channels and the inner surface of the workpiece are configured together to redirect a coolant within a space defined therebetween.

Brief Description of the Drawings

[0022] Other features and objectives of the subject matter of the present disclosure will become more apparent from consideration of the following brief description of the drawings submitted in support of these specifications. [Figure 1] A front top perspective view of a first cutting tool with a cutting insert according to the present disclosure attached thereto. [Figure 2] A top view of a first cutting tool with a cutting insert according to the present disclosure attached thereto. [Figure 3] A side elevation view of a first cutting tool with a cutting insert according to the present disclosure attached thereto. [Figure 4] An exploded front top perspective view of a first cutting tool having a cutting insert shown disassembled from various components of the cutting tool according to the present disclosure. [Figure 5] A top perspective view of a cutting tool holder to which a cutting insert according to the present disclosure is attached. [Figure 6] A top view of a cutting tool holder to which a cutting insert according to the present disclosure is attached. [Figure 7]Perspective view of the front end of a cutting tool holder to which a cutting insert according to the present disclosure is attached. [Figure 8] Perspective view of the rear end of a cutting tool holder to which a cutting insert according to the present disclosure is attached. [Figure 9] Perspective view of the back of a cutting tool holder to which a cutting insert according to the present disclosure is attached, showing in dashed lines the internal structure including a conduit for delivering a coolant to the cutting insert according to the present disclosure. [Figure 10] Perspective view of the bottom surface of an insert seat on which a cutting insert according to the present disclosure is seated. [Figure 11] Perspective view of the top surface of an insert seat on which a cutting insert according to the present disclosure is seated. [Figure 12] Enlarged front top perspective view of a cutting insert according to the present disclosure, showing the coolant cavity formed therein. [Figure 13] Front elevation view of a cutting insert according to the present disclosure, showing the coolant cavity formed therein. [Figure 14] Top view of a cutting insert according to the present disclosure. [Figure 15] Bottom view of a cutting insert according to the present disclosure. [Figure 16] Partially enlarged bottom perspective view of the upper portion of the coolant cavity of a cutting insert, enlarged to show related features in more detail. [Figure 17] Enlarged partial elevation side view of a cutting insert according to the present disclosure, showing the features of its coolant channels in more detail. 2] [Figure 18] Enlarged partial bottom view of a cutting insert according to the present disclosure, showing the features of its coolant channels in more detail. [Figure 19] Front top perspective view of a cutting insert and an insert seat assembled in relation to each other according to the present disclosure. [Figure 20] Side top perspective view of a cutting insert and an insert seat assembled in relation to each other according to the present disclosure. [Figure 21]This is a magnified top perspective view of the lower part of the cooling cavity of a cutting insert, enlarged to show related features in more detail. [Figure 22] This disclosure shows a bottom perspective view of a cutting insert and an insert seat arranged adjacent to a workpiece and assembled together. [Figure 23] This disclosure shows a top perspective view of a cutting insert and an insert seat arranged adjacent to a workpiece and assembled in relation to one another. [Figure 24] This is a side elevation view of a cutting insert and an insert seat, which are arranged adjacent to a workpiece and assembled together, according to the present disclosure. [Figure 25] Figures 22 to 24 are top perspective views of the workpiece, showing the inner surface of the workpiece after partial chip removal. [Figure 26] Figures 22 to 25 are side elevation views of the workpiece, showing the inner surface of the workpiece after partial chip removal. [Figure 27] This is a side elevation view of a milling tool to which an array of cutting inserts is attached, as per the subject matter of this disclosure. [Figure 28] This is a top view of a milling tool with an array of cutting inserts attached, as per the subject matter of this disclosure. [Figure 29] This is a bottom view of a milling tool with an array of mounted cutting inserts, as described in the subject of this disclosure. [Figure 30] This is a partial top perspective view of a milling tool according to the subject matter of this disclosure, showing the coolant inlet at the upper end of the tool. [Figure 31] This is a bottom perspective view of a milling tool fitted with an array of cutting inserts, as per the subject of this disclosure. [Figure 32] This is a first enlarged bottom perspective view of an exemplary cutting insert attached to a milling tool, according to the subject matter of this disclosure. [Figure 33] This is a second enlarged bottom perspective view of an exemplary cutting insert attached to a milling tool, according to the subject matter of this disclosure. [Figure 34] This is an enlarged bottom perspective view of an exemplary insert support portion of a milling tool, with a cutting insert removed to better show the coolant outlet formed in the insert support portion. [Figure 35] This is a third enlarged bottom perspective view of an exemplary cutting insert mounted on an insert support shown in Figure 34, according to the subject of this disclosure. [Modes for carrying out the invention]

[0023] Herein, referring more specifically to the drawings, we first refer to Figures 1 to 4, which show an overall configuration of a first cutting tool 10 incorporating the cutting insert 11 according to the subject of this disclosure. The cutting insert 11 is fixedly mounted to the cutting tool holder 12 of the first cutting tool 10. It should be noted that the cutting insert 11 according to the subject of this disclosure may be used in any type of cutting operation.

[0024] In some embodiments, the cutting insert 11 is seated on a base plate or insert seat 13 positioned between the cutting insert 11 and the open seating surface 14 of the cutting tool holder 12, within an insert space 50 formed at the first holder end 51 of the cutting tool holder 12. In some embodiments, the open seating surface 14 is angled with respect to the bottom surface 46 of the cutting tool holder 12. It will be understood that features described herein, illustrated with reference to and / or shown in the appended drawings, and / or enumerated in the appended claims, as elements constituting the insert seat 13, may also be provided on the cutting tool holder 12, and vice versa, and should not be construed as limitations.

[0025] In some embodiments, the first cutting tool 10 further comprises a clamping device 15 attached to the cutting tool holder 12 by a fastener 16. The clamping device 15 and the fastener 16 together securely attach the cutting insert 11 to the first cutting tool 10. In some embodiments, the fastener 16 may be screwed into and received within a threaded bore 48, as shown and referenced in overall in Figure 9. In some embodiments, the cutting insert 11 is attached to the cutting tool holder 12 on an insert seat 13. In some embodiments, the clamping device 15 has a front end 17 configured to be received in a mounting bore 18 formed in the cutting insert 11. The mounting bore 18 may be configured to allow a portion of the clamping device 15 to be received therein while applying force to at least one of the side walls and / or bottom of the mounting bore 18, thereby the clamping device 15 also securely attaches the cutting insert 11 to the cutting tool holder 12, which is connected by the fastener 16 and a spring pin 49. In some embodiments, the fastener 16 and the spring pin 49 are received in bores 48 and 47 formed in the cutting tool holder 12, respectively.

[0026] In particular, the first cutting tool 10 provides a cooling supply configuration that works in cooperation with at least one cooling channel 31 provided by the cutting insert 11 to cool the corner cutting regions 28 of the cutting insert 11. In some embodiments, the cutting insert 11 may have cooling channels 31 facing each corner cutting region 28. For the purposes of these specifications, the first cooling channels 31 and the first corner cutting regions 28 are discussed in detail, and further details may be given to similar features of the cutting insert 11, as may be further specified as needed after the cooling channels 31 and the corner cutting regions 28 have been discussed.

[0027] Returning to the cooling supply configuration according to the subject matter of this disclosure, refer to Figure 9. Further referring to Figure 9, we will consider the cooling supply configuration as a whole. The cooling supply configuration comprises a conduit 19 which may extend along or through the length of the cutting tool holder 12 and has a coolant discharge opening 20 at the open seating surface 14 of the first holder end 51. The first cutting tool 10 further provides a coolant inlet 25 at the second holder end 52 of the cutting tool holder 12. In embodiments including an insert seat 13, the coolant discharge opening 20 is aligned with a through bore formed in the insert seat 13.

[0028] More specifically, the lower tool-facing surface 21 of the insert seat 13 has a liquid inlet such as 22, and the upper insert-facing surface 23 of the insert seat 13 has a liquid outlet 24 that is in fluid communication with a coolant inlet 74 located in the upstream section 30 of at least one cooling channel 31. In other words, the through bore interconnects the liquid inlet 22 and the liquid outlet 24, and the liquid outlet 24 is in fluid communication with the coolant inlet 74 of at least one cooling channel 31. Referring to Figure 8, consider the coolant path as indicated by arrow 105 through the cutting tool holder 12. The coolant enters the cutting tool holder 12 at the coolant inlet 25 and is guided through the conduit 19 to a coolant discharge opening 20 or outlet formed in the open seat surface 14. When implemented with the insert seat 13, the liquid discharge opening 20 is in fluid communication with the liquid inlet 22 of the insert seat 13, the liquid inlet 22 is in fluid communication with the liquid outlet 24 of the insert seat 13, and the liquid outlet 24 discharges coolant into at least one cooling channel 31 in the upstream section 30 of the cutting insert 11 that is downward adjacent to the corner cutting region 28 in order to cool the corner cutting region 28 of the cutting insert 11.

[0029] The central implementation of the subject matter of this disclosure is the cutting insert 11. The cutting insert 11 according to the subject matter of this disclosure comprises a body 70 having an upper insert surface 35 defining an upper insert plane 109, a lower insert surface 36 defining a lower insert plane 108, and at least one side wall 71 extending between them. In some embodiments, the cutting insert 11 comprises opposing side walls 71 extending opposite to the front insert plane 110, as shown and referenced in whole in Figure 14. In some embodiments, each side wall 71 comprises two side wall portions, such as 73, angled relative to each other around the insert central plane 100. Thus, in some embodiments, the cutting insert 11 comprises two side walls 71 and four side wall portions 73. In some embodiments, the body 70 of the cutting insert 11 is rhombic or square having a series of side wall surfaces 37 extending between the upper insert surface 35 and the lower insert surface 36. In some embodiments, the cutting insert 11 further comprises at least one corner cutting region 28 defined between at least one side wall 71 and the upper insert surface 35.

[0030] In some embodiments, at least one side wall 71 defines a coolant flow path 101 extending between it and its upstream section 30, and is formed together with at least one cooling channel 31 having a coolant inlet 74 facing the lower insert plane 108. The cooling channel 31 further comprises a downstream section 72 extending below the corner cutting region 28. In some embodiments, the coolant flow path 101 is at least partially exposed to the outside 111 of the cutting insert 11, referring to Figures 12, 14, and 15. The cooling channel 31 further comprises an arc-shaped portion 32 between the upstream section 30 and the downstream section 72. The coolant flow path 101 is characterized by following a virtual midline 112 passing through the coolant flow path 101, which is depicted as a dashed line in Figure 18. In some embodiments, the coolant flow path 101 is an arc-shaped path, as shown overall in Figures 13, 17, and 20.

[0031] In some embodiments, the arcuate portion 32 is characterized by a single smooth curve along at least a portion of the coolant channel 101 extending in a flow plane defined by the X-axis 113 and the Y-axis 114, as shown in Figure 17. Referring to Figure 18 in comparison, it can be seen that the coolant channel 101 is straight along a virtual midline 112 in the flow plane defined along the X-axis 113 and the Y-axis extending in the page. The Z-axis 115 extends across the sidewall 71 and sidewall portion 73, as further referenced in Figure 18, for the reader's understanding. In some embodiments, the morphology of the arcuate portion 32 generates pressure in the coolant guided along the arcuate portion 32 by a centrifugal force 120 directed radially outward from the coolant channel 101 along the arcuate portion 32, thereby increasing the coolant flow along the coolant channel 101 and increasing heat removal in the corner cutting region 28 of the downstream section 72.

[0032] In some embodiments, the single smooth curve defined by the arcuate portion 32 has a radius in three dimensions along at least a portion of it. In this regard, see further Figures 17 and 18. Referring to Figure 17, for example, it can be seen that the radius of the coolant flow path 101 in the upstream section 30 is maximized or virtually infinite, and as a result, the centrifugal force 120 does not appear in the upstream section 30. In other words, the coolant flow path 101 is more linear in the upstream section 30. As the coolant flow path 101 proceeds toward the downstream section 72, the radius of the arcuate portion 32 smoothly decreases in response to the gradually increasing centrifugal force 120. Thus, in some embodiments, the single smooth curve has a decreasing radius along at least a portion of the coolant flow path 101 extending from the upstream section 30 toward the downstream section 72, corresponding to the gradually increasing centrifugal force 120 along that portion of the coolant flow path 101.

[0033] Referencing Figure 18 for comparison, the upstream section 30 and the coolant flow path 101 therefrom are further examined. In some embodiments, a single smooth curve has a radius that increases in dimension as it crosses the coolant flow path 101 from the upstream section 30 toward the downstream section 72. More specifically, Figure 18 shows the inlet radius at the coolant inlet 74 as 116. The arcuate portion 32 further comprises at least a first radially shaped portion 75 and at least a second radially shaped portion 76 located downstream of the first radially shaped portion 75 along the length of the arcuate portion 32. The first radially shaped portion 75 has a radius 117 that is greater than the inlet radius 116, and the second radially shaped portion 76 has a radius 118 that is greater than the radius 117. The radii 116, 117, and 118 are gradually increased by the inclined inner wall surface 77 of the outer wall portion 54 extending along the wall length 125. In other words, the inclined inner wall surface 77 is angled obliquely with respect to the inner cavity surface 39 of the wall cavity 79 in which the cooling channel 31 is formed. In some embodiments, the inner cavity surface 39 is parallel to the outer side wall surface 37 of the side wall 71.

[0034] Returning to Figure 17, it can be seen that in some embodiments, the arc portion 32 extends along the coolant channel 100 with respect to the lower insert surface 36 and the lower insert plane 108 over an arc length of at least 90 degrees. In some embodiments, the arc portion 32 extends from the lower insert plane 108 along the coolant channel 100 over an arc length of more than 90 degrees. In some embodiments, the arc portion 32 extends from the lower insert plane 108 over an arc length in the range of 105 to 125 degrees. Thus, in some embodiments, the arc portion 32 is configured to guide the coolant downward along the coolant channel 101 in the corner cutting region 28, as in 119 relative to the upper insert plane 109, in order to enhance heat removal in the corner cutting region 28 during cutting operations and to guide the coolant downward into the workpiece 26, as will be described in more detail below.

[0035] As described above, it will be understood that the cooling channel 31 is formed within a wall cavity 79 exposed to the outside 111 of the cutting insert 11 and has an arc-shaped portion 32. The arc-shaped portion 32 guides the coolant along a coolant channel such as 101, which follows a midline 112. In some embodiments, the coolant channel 101 is an arc-shaped path within the cooling channel 31 formed in the wall cavity 79. In other words, in some embodiments, the cooling channel 31, which is in fluid communication with the liquid outlet 24, is curved or arc-shaped at its top, and the coolant is applied to the arc-shaped portion 32 by centrifugal force 120 to bring as much coolant volume as possible towards the cutting edge 27 of the corner cutting region 28. The cooling channel 31 is essentially configured to extend from the upstream section 30 of the cutting insert 11 toward the downstream section 72 of the corner cutting region 28.

[0036] The cutting insert 11 according to the present invention comprises at least one cutting edge 27 associated with a corner cutting region 28 of the cutting insert 11. Each cutting edge 27 is formed midway between a rake face, such as 57, which is generally characterized by the upper insert surface of the cutting insert 11, and a side face, such as 58, which is generally characterized by the upper part of the side wall surface 37' of the side wall 71 of the cutting insert 11, with general and relative reference to Figures 16 to 20. In some embodiments, a wall cavity 79 is associated with the corner cutting region 28 and is formed below the corner cutting region 28 within a side wall surface 37 defined inward relative to the outside 111 by an internal cavity surface 39. The externally exposed wall cavity 79 is configured to draw heat from the cutting corner 28 during the cutting operation of the workpiece 26.

[0037] In other words, the corner cutting area 28 has at least one rake face 57 on the upper insert surface 35 and at least one side surface 58 on the side wall surface 37', thereby providing at least one cutting edge 27. In some embodiments, the cooling channel 31 extends from the side surface 58 to the lower insert surface 36. In some embodiments, an externally exposed wall cavity 79 is configured to allow the introduction of a coolant into it during a cutting operation performed on the workpiece 26, as shown and referenced in whole in Figures 22–26. During such a cutting operation, the corner cutting area 28 is constantly heated to a high temperature due to the high friction between itself and the workpiece 26. The coolant flows into the wall cavity 79 through the cooling channel 31, thereby intended to absorb and remove the heat transferred from the corner cutting area 28 to the wall cavity 79. As a result, the corner cutting area 28 is effectively cooled during the cutting operation, reducing the wear resulting from that operation.

[0038] The wall cavity 79 is positioned midway between the corner cutting area 28 and the upper seating surface 23 of the insert seat 13, allowing the coolant to effectively extract heat from the corner cutting area 28. To enable effective heat extraction from the cutting edge 27 and the corner cutting area 28, at least a portion of the wall cavity 79 is positioned adjacent to the corner cutting area 28, at a distance from the cutting edge 27, so as to minimize structural damage to the cutting edge 27 and maintain the structural integrity of the cutting edge 27. The cooling channel 31 formed in the wall cavity 79 is configured to receive the coolant from the liquid outlet 24 of the insert seat 13 in the upstream section 30 to remove heat from the structure of the corner cutting area 28, the cutting edge 27, and in particular the cutting insert 11 positioned between the cutting edge 27 and the wall cavity 79.

[0039] In some embodiments, a large portion of the coolant flow path 101 is exposed to the outside 111 of the cutting insert 11. In this regard, the coolant inlet 74 of the upstream section 30 includes or is partially defined by an outer wall portion 54. Thus, in some embodiments, the upstream section 30 may include an outer wall portion 54 that defines the liquid inlet 74 and is located on the side of the liquid outlet 24 to guide the coolant from the liquid outlet 24 to the cooling channel 31. In some embodiments, the upstream section 30 in the outer wall portion 54 is continuous with the internal cavity surface 39 in a radially oriented portion 55.

[0040] In some embodiments, the radially tapered portion 55 may be configured to correspond to the outlet diameter 107 of the liquid outlet 24. In other words, the liquid inlet 74 includes an inlet diameter corresponding to the outlet diameter in some embodiments. In some embodiments, the outer wall portion 54 slopes toward the arc portion 32 and is smooth with the arc portion 32 at a smooth transition point 56 between the upstream section 30 and the downstream section 72 in the corner cutting region 28. In some embodiments, the downstream section 72 extends from the arc portion 32 toward the bank portion 40. The arc portion 32 is designed to apply the coolant to the arc portion 32 by centrifugal force, thereby increasing the coolant flow along the coolant channel 101 in the corner cutting region 28 to remove heat from the corner cutting region 28. The bank portion 40 redirects the coolant toward the workpiece 26, as indicated by arrow 121, to absorb heat from there.

[0041] In some embodiments, the majority of the coolant channel 101 is exposed toward the downstream section 72, while the remaining or small portion of the coolant channel 101 is not exposed or enclosed in or adjacent to the upstream section 30. In some embodiments, the upstream section 30 may be said to include an outer wall portion 54 adjacent to the outer portion of the coolant inlet 74 for guiding the coolant from the coolant outlet 24 into the cooling channel 31. In some embodiments, the outer wall portion 54 gradually slopes toward a smooth transition point 26 such that the majority of the coolant channel 101 is exposed toward the outside 111 of the cutting insert 11. In other words, in some embodiments, the coolant channel 101 in the upstream section 30 is not exposed or enclosed so as to be included in the inner wall surface 77 of the outer wall portion 54 that slope toward a smooth transition point 56. The coolant channel 101 can be said to include both exposed and enclosed portions along the coolant channel 101, which together combine to form an exposed / enclosed coolant flow. In some embodiments, the coolant flow path 101 is exposed in increasing proportions from the upstream section 30 to the downstream section 72.

[0042] In some embodiments, the coolant inlet 74 has an inlet radius such as radius 116. In some embodiments, the outer wall portion 54 is angled or inclined with respect to the inner cavity surface 39 of the wall cavity 79 to increase the coolant flow path width 123 relative to the inlet radius 116 as the coolant is guided along the coolant flow path 101 toward the downstream section 72. In some embodiments, the upstream section 30 of the outer wall portion 54 is located outside the cutting insert 11 and is radiused or dimensioned in accordance with the diameter 107 of the coolant outlet 24 which is in fluid communication with it. In some embodiments, the outer wall portion 54 is inclined toward the arcuate portion 32 and becomes smooth with the arcuate portion 32 at a smooth transition point 56 between the upstream section 30 and the downstream section 72 in the corner cutting region 28.

[0043] In some embodiments, the coolant channel 101 may be further guided or influenced by an arc-shaped bank portion 53 extending along the arc-shaped portion 32. In some embodiments, the arc-shaped bank portion 53 is inclined from the arc-shaped portion 32 toward the internal cavity surface 39 to guide the coolant along the internal cavity surface 39 of the wall cavity 79, as shown by arrow 122 in Figure 17. The arc-shaped portion 32 terminates in the downstream section 72 of the insert central plane 100 of the bank portion 40. In some embodiments, the bank portion 40 is located in the center of the central plane 100, which further guides the coolant flow toward the workpiece 26 and the wall cavity 79, as shown by arrow 121. In some embodiments, the cooling channel 31 is configured to cooperately face the inner surface 33 of the workpiece during cutting operations, redirecting the coolant within a defined space between the inner surface 33 of the workpiece and the corner cutting area 28.

[0044] In some embodiments, as described above, the cutting insert 11 according to the subject of this disclosure may comprise at least one sidewall 71 including two sidewall portions 73 angled relative to each other. In some embodiments, the two sidewall portions 73 together define a branched wall cavity 29 below the corner cutting region 28. In other words, the branched wall cavity 29 comprises wall cavities 79 that are in fluid communication with each other. In some embodiments, the cutting insert 11 comprises a corner cutting region 28 defined between two first adjacent sidewall surfaces, such as 37' and 37'', and a second adjacent sidewall surface, and the upper insert surface 35. In some embodiments, at least one cooling channel 31 is formed within the branched wall cavity 29, at least a portion of which is exposed to the outside of the insert 111. In some embodiments, opposing cooling channels 31 are formed within the branched wall cavity 29.

[0045] In some embodiments, opposing cooling channels 31 that are in fluid communication with each other are formed within the branch wall cavity 29. In some embodiments, the branch wall cavity 29 is characterized by two opposing externally exposed cooling channels 31 that extend symmetrically across the insert central plane 100, which extends perpendicular to the plane 102 of the cutting insert 11 and intersects the cutting insert 11 obliquely in the middle of the lateral halves of the triangle. In some embodiments, the opposing cooling channels 31 together define a branched cooling channel flow path, whose opposing portions are angled relative to each other and directed toward the corner cutting region 28 in at least the downstream section 72. In some embodiments, the insert central plane 100 extends perpendicular to the upper insert surface 35 and the lower insert surface 36, and the branch wall cavity 29 is symmetrical across the insert central plane 100. In some embodiments, the opposing cooling channels 31 formed within the branch wall cavity 29 are symmetrical across the insert central plane 100.

[0046] In some embodiments, the upper insert surface 35 of the cutting insert 11 is generally rhomboid in shape, as schematically shown in Figure 14. In these embodiments, the cutting insert 11 has acute angles 103 at the corner cutting area 28 and the insert corner 45 opposite the corner cutting area 28, and obtuse angles 104 at the laterally opposite corners 44 of the cutting insert 11. In certain embodiments, the insert central plane 100 extends through the acute angles 103 at the corner cutting area 28 and the insert corner 45. In some embodiments, the cutting insert 11 may have a different shape (e.g., square). In other words, although the illustrated shape of the cutting insert 11 is depicted as generally rhomboid, the illustrated embodiments are illustrative and should not be construed as limiting.

[0047] In some embodiments, the corner cutting area 28 comprises opposing cutting blades 27 angled toward each other. In some embodiments, the corner cutting area 28 comprises a curved cutting blade 59 between the opposing cutting blades 27. In some embodiments, the corner cutting area 28 comprises a tapered portion 60 above the corner bank portion 40, spaced apart from the curved cutting blade 59. To facilitate heat removal from the corner cutting area 28, the cutting blades 27, and the workpiece 26, during the cutting operation, at least a portion of the inner surface 33 of the workpiece is further guided into a cooling channel 31 to contain the coolant or to redirect the coolant as indicated by arrow 106.

[0048] Refer further to Figures 22 to 26 to consider the workpiece 26 during machining. Note that during the cutting operation, the workpiece 26 itself contributes to containing the coolant in the branch wall cavity 29 or redirecting the coolant as indicated by arrow 106. The inner surface 33 of the workpiece 26 contains and / or redirects the coolant flowing through the branch wall cavity 29 as the cutting blade 27 removes chips 34 from the workpiece 26. Depending on the dimensional characteristics of the workpiece 26, in some applications the branch wall cavity 29 may open at least partially to the outside of the cutting insert 11 during the cutting operation, as shown overall in Figures 24 to 26, allowing the coolant to flow from there.

[0049] In this disclosure and claims, terms relating to directions such as top and bottom, upper and lower, up and down, and similar terms / related terms will be used with reference to the accompanying drawings and should not be construed as limiting unless otherwise indicated or made clear from the context. The term “horizontal” with respect to an element, for example, a face or line of a cutting insert, usually means that the face / line is approximately horizontal when the element is positioned horizontally in its working orientation, and the term “vertical” with respect to a face / line of an element, usually means that the face / line is approximately vertical when the element is positioned horizontally in its normal orientation. The term “front side” (and similar terms) refers to the direction toward the workpiece 26, and the term “rear side” (and other similar terms) refers to the direction toward the workpiece 26.

[0050] As described above, the cutting insert 11 according to the subject matter of this disclosure may comprise an upper insert surface 35, a lower insert surface 36, and a plurality of sidewall surfaces 37 extending between them. In some embodiments, the upper insert surface 35 and the lower inset surface 36 may be oriented horizontally, and the sidewall surfaces 37 may be oriented vertically. The plurality of sidewall surfaces 37 include a first sidewall surface such as 37' and a second sidewall surface such as 37'' adjacent to the first sidewall surface 37'. The corner cutting region 28 is defined between the upper part of the first sidewall surface 37', the upper part of the second sidewall surface 37'', and the corner portion of the horizontal upper insert surface 35. A branch wall cavity 29 is located below the corner cutting region 28, with the arcuate upper part 32 of an opposing cooling channel 31 extending below it. In a particular embodiment, the rake face 57 provided by the horizontal upper insert surface 35 and the side surface 58 provided by the upper parts of the first side wall surface 37' and the second side wall surface 37'' may define opposing cutting edges 27.

[0051] In some embodiments, at least the corner cutting area 28 may be coated with a first coating material having reduced thermal conductivity relative to the corner cutting area 28 to provide greater thermal durability in the corner cutting area 28 in order to reduce the effects of heat generated during the cutting process of the corner cutting area 28 and to increase the effective life of the cutting insert 11. In some embodiments, the wall cavity 79 and branch wall cavity 29 may have a cooling surface defined by an internal cavity surface 39, which may not include the first coating material, in order to increase heat transfer between the coolant flowing through the wall cavity 79 and branch wall cavity 29 and the corner cutting area 28, i.e., to achieve the opposite effect of increasing thermal conductivity and thereby increasing heat absorption from the corner cutting area 28.

[0052] In some embodiments, the cutting insert 11 may further comprise a mounting component, such as a mounting bore 18, configured to engage with specific fastening elements, such as a clamping device 15 and a fastener 16, thereby fixing and holding the cutting insert 11 on the cutting tool holder 12 and / or insert seat 13. The mounting bore 18 may be in the form of a vertical through bore, and the fastening element may be in the form of a fastener 16 configured to be received therein and inserted into a corresponding fastener receiving bore 48 formed within the cutting tool holder 12. The mounting bore 18 is a centrally located through bore extending between the horizontal upper insert surface 35 and the horizontal lower insert surface 36 of the cutting insert 11, and has an axis that constitutes the central axis of the cutting insert 11.

[0053] In some embodiments, the cutting insert 11 is double-sided and has at its front end a corner cutting area 28 defined at the intersection of a related area of ​​either one of the horizontal upper insert surface 35 or lower insert surface 36 and two adjacent side wall surfaces 37' and 37''. In certain embodiments, the cutting insert 11 has at least one cutting edge 27. In some embodiments, the cutting insert 11 may have different configurations and several interchangeable corner cutting areas 28 having cutting edges 27. For example, the cutting insert 11 may have an interchangeable cutting edge on its upper insert surface 35, or it may have a polygon other than a rhombus (e.g., a square).

[0054] It should be understood that the description relating to at least one cutting edge 27 and its associated cooling channel 31 should be considered applicable to each of the cutting edges 27 of the cutting insert 11. In other words, in some embodiments, a branch wall cavity 29 may comprise opposing cooling channels 31, at least a portion of which extend along at least one cutting edge 27 while moving away from the cutting edge 27. In this specification and in the claims, the term “channel” means a region having at least one coolant guide wall, at least a portion of which moves away from the rest of the upper insert surface 35 associated with the cutting edge 27 toward the other lower insert surface 36. Each cooling channel 31 according to the subject matter of this disclosure has an arc-shaped upper 32 that functions similarly to a bank turn, having a substantially flat internal cavity surface 39 that extends substantially parallel to the side wall surfaces 37' and 37'', guiding the coolant along an arc-shaped coolant flow path 101 within its respective wall cavity 79.

[0055] As described in various ways, in some embodiments, the corner cutting region 28 is located above opposing external cooling channels 31 that together form a branched wall cavity 29, which may be described as a branched cooling cavity 29. Each cooling channel 31 has an upstream section 30 located above a liquid outlet 24, providing fluid communication between them. The branched cooling cavity or wall cavity 29 comprises a central corner bank portion such as 40, opposing arcuate portions such as 32, and opposing internal cavity surfaces such as 39. Each cooling channel 31 extends away from the upstream section 30 toward the corner cutting region 28 and includes a downstream section 72 positioned spaced apart therefrom along the cutting edge 27.

[0056] In some embodiments, the insert seat 13 may comprise two through bores for injecting coolant in a similar upstream section 30 positioned above the liquid outlet 24 to guide the coolant along the arcuate section 32 toward the central bank section 40, and an internal cavity surface 39. The shape and orientation of the cooling channel 31, particularly with respect to the upstream section 30, may be configured to allow a directional flow of coolant along the inner surface of the cooling channel 31 at a desired speed to provide a sufficient amount of surface area exposed to the coolant and to reduce the amount of fluid escaping from the cooling channel 31 depending on the dimensions of the workpiece 26, the workpiece inner surface 33 which helps to contain the coolant in the branched cooling cavity 29 and / or redirect the coolant flow as one or more cutting edges 27 remove chips 34 from the workpiece 26. In some embodiments, the corner cutting area 28 may further comprise a curved cutting edge 59 between the opposing cutting edges 27. In some embodiments, the corner cutting region 28 may have a tapered portion 60 above the corner bank portion, spaced apart from the curved cutting blade 59.

[0057] When an insert seat 13 is used to mount a cutting insert 11 to a cutting tool holder 12, such an insert seat 13 may have an insert-facing surface 23 to which the corresponding cutting insert 11 can be mounted, a tool-facing surface 21, and a base sidewall 41 extending between them. The insert-facing surface 23 may be formed in correspondence with the lower insert surface 36 and sidewall surface 37 of the corresponding cutting insert 11. The insert-facing surface 23 may have at least one liquid outlet 24 formed therein, configured to provide fluid communication with the upstream section 30 of at least one cooling channel 31. In some embodiments, the insert-facing surface 23 may have at least two liquid outlets 24 formed therein, configured to provide fluid communication with the upstream sections 30 of opposing cooling channels 31 formed in a branched cooling cavity or wall cavity 29. In these embodiments, corresponding through bores may be formed in each such insert seat 13 to connect a conduit 19 to the liquid outlet 24.

[0058] Referring to Figures 27 to 35, a second cutting tool or milling tool 200 according to the subject matter of this disclosure will be considered. The milling tool 200 comprises an array of cutting inserts 11 arranged around the milling tool 200 at the cutting end 201 of the milling tool 200. In some embodiments, a coolant may be introduced into the milling tool 200 via the tool end 211 opposite the cutting end 201. The coolant then exits the milling tool 200 via the cutting inserts 11 at the cutting end 201, substantially as described above. In some embodiments, the milling tool 200 may rotate around a tool rotation axis 202 as shown by arrow 204, so that the cutting inserts 11 can cut to mill a millable surface 203. In some applications, the cutting insert 11 is suitable to be formed and used as a positive cutting insert 11, and a single face-to-face cooling channel 31' of each cutting insert 11 is operable to cool the cutting corner area 28 of each cutting insert 11 as each cutting insert 11 rotates 204 around the tool rotation axis 202 toward the millable surface 203.

[0059] Referring to Figure 30, the tool end 211 of the milling tool 200 is examined in more detail. In some embodiments, a coolant inlet 205 is formed in the main tool body 206 of the milling tool 200 at or adjacent to the tool end 211. The coolant can be guided into the coolant inlet 205 and directed toward the cutting end 201 via a conduit path 207 formed in the main tool body 206 toward a coolant outlet 208 formed in an insert support portion 209 configured around the periphery of the milling tool 200 at the cutting end 201. Referring to Figure 34, for example, a substantially planar insert support portion 209 is considered, configured so that a single coolant outlet 208 supports the lower insert surface 36 of a cutting insert formed inside.

[0060] In some embodiments, the cutting insert 11 is mounted on the insert support portion 209 such that the coolant inlet 74 in the upstream section 30 of the face-to-face cooling channel 31' aligns with the coolant outlet 208 of the insert support portion 209. In some embodiments, the insert support portion 209 further comprises a fastener receiving opening 210 that cooperates with a mounting bore 18 formed in the cutting insert 11. Fasteners 212 securely fasten each cutting insert 11 to each insert support portion 209 via the coaxially aligned fastener receiving openings 210 and mounting bore 18.

[0061] In other words, in some embodiments, each cutting insert 11 that can be attached to the milling tool 200 is formed and suitable for use as a positive cutting insert having a single cutting edge 27 in a corner cutting area 28 facing a millable surface 203. The array of cutting inserts 11 of the milling tool 200 is arranged and configured so that a coolant can be guided into a face-to-face cooling channel 31' facing the millable surface 203 of the milling tool 200, which extends generally laterally with respect to the tool rotation axis 202. The coolant enters the face-to-face cooling channel 31' in the upstream section 30 of the cutting insert 11 and is guided along the coolant flow path 101 toward the corner cutting area 28 of the cutting insert 11, cooling the corner cutting area 28 as the milling tool 200 mills or cuts the millable surface 203.

[0062] In some embodiments, the externally opposed cooling channel 31'', which faces the exterior 111 and extends substantially parallel to the tool rotation axis 202, is not necessarily configured to guide coolant into it in order to direct coolant toward the central corner cutting region 28. In other words, in some applications, the externally opposed cooling channel 31'' is not configured to have a coolant outlet and a coolant inlet aligned with a coolant outlet formed in the insert support portion 209 of the milling tool 200. This means that although the branch wall cavity 29 adjacent to the corner cutting region 28 assists in heat transfer from the corner cutting region 28, it may still be possible for coolant to enter the space defined by both the surface-facing cooling channel 31' and the externally opposed cooling channel 31''. Otherwise, the cutting insert 11 of the milling tool 200 is configured to operate substantially as described above in some embodiments.

Claims

1. A cutting insert comprising a body having an upper insert surface, a lower insert surface defining a lower insert plane, and at least one side wall extending between the upper insert surface and the lower insert surface, and having at least one corner cutting region defined between the at least one side wall and the upper insert surface, The cutting insert is formed with at least one cooling channel that defines a coolant flow path extending between an upstream section of the cutting insert having a coolant inlet facing the lower insert plane and a downstream section of the cutting insert extending below the at least one corner cutting region, wherein the coolant flow path is at least partially exposed to the outside of the cutting insert and has an arc-shaped portion between the upstream section and the downstream section.

2. The cutting insert according to claim 1, wherein the arc-shaped portion is characterized by a single smooth curve along at least a portion of the coolant flow path.

3. The cutting insert according to claim 2, wherein the single smooth curve extends along a planar dimension parallel to the side wall.

4. The cutting insert according to any one of claims 1 to 3, wherein the arc-shaped portion generates pressure in the coolant guided along the arc-shaped portion, thereby increasing the coolant flow along the coolant channel and increasing heat removal in the corner cutting region.

5. The cutting insert according to any one of claims 1 to 4, wherein the arc-shaped portion has a radius in three dimensions along at least a part thereof.

6. The cutting insert according to claim 5, as dependent on claim 4, wherein the arc-shaped portion has a decreasing radius corresponding to an increasing centrifugal force along the portion of the coolant flow path that extends from the upstream section toward the downstream section.

7. The cutting insert according to claim 5 or 6, as dependent on claim 4, wherein the arc-shaped portion has a radius that increases in the dimension across the coolant flow path from the upstream section to the downstream section.

8. The cutting insert according to any one of claims 1 to 7, wherein the arc-shaped portion extends along the coolant flow path over an arc length of at least 90 degrees.

9. The cutting insert according to any one of claims 1 to 8, wherein the arc-shaped portion extends along the coolant flow path over an arc length of more than 90 degrees.

10. The cutting insert according to any one of claims 1 to 9, wherein the arc-shaped portion extends over an arc length in the range of 105 to 125 degrees.

11. The cutting insert according to any one of claims 1 to 10, wherein the arc-shaped portion is configured to guide the coolant downward along the coolant flow path in the corner cutting region in order to enhance heat removal in the corner cutting region.

12. The cutting insert according to any one of claims 1 to 11, wherein the cooling channel is formed within a wall cavity and at least a portion of the cooling channel is exposed to the outside of the cutting insert.

13. The cutting insert according to claim 12, wherein the majority of the coolant flow path is exposed to the outside of the cutting insert.

14. The cutting insert according to claim 13, wherein most of the coolant flow path is exposed toward the downstream section, and a small portion of the coolant flow path is enclosed toward the upstream section.

15. The cutting insert according to claim 14, wherein the coolant flow path in the upstream section is enclosed from the outside, so that the coolant flow path includes an exposed portion and an enclosed portion along the coolant flow path, and the exposed portion and the enclosed portion together form a combined coolant flow.

16. The cutting insert according to any one of claims 12 to 15, wherein the coolant flow path is gradually exposed from the upstream section toward the downstream section.

17. The cutting insert according to any one of claims 12 to 16, wherein the outer wall portion surrounds the coolant inlet in the upstream section.

18. The cutting insert according to claim 17, wherein the outer wall portion is inclined toward the arc-shaped portion and becomes smooth together with the arc-shaped portion at a smooth transition point between the upstream section and the downstream section.

19. The cutting insert according to claim 17 or 18, wherein the coolant inlet has an inlet radius, and the outer wall portion is inclined with respect to the coolant inlet to increase the coolant flow path width with respect to the inlet radius as the coolant is guided along the coolant flow path toward the downstream section.

20. A cutting insert according to any one of claims 12 to 19, comprising an arc-shaped bank portion that extends along the arc-shaped portion and is inclined from the arc-shaped portion toward the internal cavity surface of the wall cavity, for guiding a coolant along the arc-shaped portion.

21. The cutting insert according to claim 20, wherein the internal cavity surface is parallel to the coolant flow path.

22. The cutting insert according to claim 20 or 21, wherein the internal cavity surface extends parallel to the side wall surface of the side wall.

23. The cutting insert according to any one of claims 1 to 22, wherein the coolant inlet has an inlet diameter configured to receive coolant from a coolant outlet that is in fluid communication with the coolant inlet.

24. The cutting insert according to claim 23, wherein the coolant outlet has an outlet diameter corresponding to the inlet diameter.

25. The cutting insert according to any one of claims 1 to 24, wherein the corner cutting region comprises a corner bank portion configured to redirect the coolant downwards from the corner cutting region.

26. The cutting insert according to any one of claims 1 to 25, wherein the side wall includes opposing side wall portions that are angled relative to each other.

27. The cutting insert according to claim 26, wherein the opposing side wall portions together define a branch wall cavity below the corner cutting region.

28. The cutting insert according to claim 27, wherein the branch wall cavity comprises opposing cooling channels that are in fluid communication with each other.

29. The cutting insert according to claim 28, wherein the opposing cooling channels together define a branched cooling channel flow path, and the opposing portions of the branched cooling channel flow path are angled relative to each other and guided toward the corner cutting region.

30. A cutting insert according to any one of claims 27 to 29, wherein the central plane of the insert extends perpendicularly to the upper insert surface and the lower insert surface, and the branch wall cavity is symmetrical with respect to the central plane of the insert.

31. A cutting insert according to any one of claims 28 to 30, as dependent on claim 27, wherein the opposing cooling channels formed in the branch wall cavity are symmetrical with respect to the central plane of the insert.

32. The cutting insert according to any one of claims 1 to 31, wherein the corner cutting region has a rake surface on the upper insert surface and a side surface on the side wall surface, thereby providing at least one cutting edge on the upper insert surface.

33. The cutting insert according to claim 32, wherein at least one cooling channel extends from the side surface to the lower insert surface.

34. The cutting insert according to claim 32 or 33, wherein the corner cutting region comprises opposing cutting blades angled toward each other.

35. The cutting insert according to claim 34, wherein the corner cutting region comprises a curved cutting blade between the opposing cutting blades.

36. The cutting insert according to claim 35, wherein the corner cutting region has a tapered portion above the corner bank portion, spaced apart from the curved cutting blade.

37. The cutting insert according to any one of claims 1 to 36, wherein the main body has a rhomboid shape with acute angles in the corner cutting region and the insert corner opposite the corner cutting region.

38. The cutting insert according to any one of claims 1 to 37, wherein the cooling channel is configured to face the workpiece during cutting.

39. The cutting insert according to claim 38, wherein the workpiece has an inner surface, and the cooling channel and the inner surface of the workpiece are configured together to redirect a coolant in a space defined between the cooling channel and the inner surface of the workpiece.

Images