Tool body and milling tool

Abstract

1. A tool body (2) for a milling tool (1), comprising: a front end (3) and a rear end (4) between which a central axis (C) and a peripheral envelope surface (5) extend, the tool body (2) being configured to be rotated in a direction of rotation (R) about the central axis (C); at least one insert seat (6) configured to support a cutting insert (7); and a chip pocket (8) located forward of the insert seat in the direction of rotation and bounded by a wall surface (9), wherein a surface pattern including a plurality of first grooves and a plurality of second grooves is formed on at least a portion of the wall surface, the second grooves intersecting the first grooves, and each of the first grooves and / or each of the second grooves having a concave groove profile. [Selected Figure] Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tool body for a milling tool and to a milling tool comprising such a tool body according to the preamble of claim 1. The present invention also relates to a method for manufacturing a tool body for a milling tool. [Background technology]

[0002] For certain milling applications and workpiece materials, there is a risk of chip blockage during evacuation through the chip pocket. This can cause chip jamming, which in turn can cause problems such as milling tool breakage or a poor-quality surface being machined. The chip pocket for chip evacuation is provided in front of the cutting edge of the milling tool and should therefore be designed to minimize the risk of chip jamming.

[0003] EP1654085 discloses a milling tool including a tool body and a plurality of cutting inserts mounted therein. A chip pocket is provided in front of each cutting insert for the evacuation of chips formed during machining. The walls that bound the chip pockets are formed with a plurality of smooth grooves, which are separated by continuous ridges extending along the grooves. However, there is a risk that the chips will continually rub against the ridges, which will slow down the chip flow. Summary of the Invention

[0004] It would be desirable to provide, in at least some aspects, improved tool bodies for milling tools. In particular, it would be desirable to provide tool bodies that contribute to reducing friction in the chip evacuation process during machining. It would also be desirable to provide, in at least some aspects, improved methods of manufacturing tool bodies for milling tools.

[0005] To better address these concerns, a tool body for a milling tool, as defined above, is provided. The tool body comprises: a front end and a rear end, between which a central axis and a peripheral envelope surface extend, the tool body being configured to be turned in a direction of rotation about the central axis; at least one insert seat formed at a transition between the leading end and the peripheral envelope surface, the at least one insert seat configured to support a cutting insert adapted to be mounted thereon; a chip pocket provided in front of the insert seat in the direction of rotation, the chip pocket being bounded by a wall surface.

[0006] The tool body is characterized by the following: a surface pattern including a plurality of first grooves and second grooves formed on at least a portion of the wall surface, the second grooves intersecting the first grooves, and each groove of the first grooves and / or each groove of the second grooves having a concave groove profile.

[0007] According to another aspect, the present invention relates to a method for manufacturing the tool body as presented, said method comprising the steps of: providing a tool body blank; removing material from a tool body blank with a first tool to create a space forming a chip pocket; Processing an insert sheet; generating a first groove in the wall surface with a first ball nose milling cutter; creating a second groove in the wall surface with a second ball nose milling cutter, preferably the same milling cutter as the first ball nose milling cutter, such that the second groove intersects with the first groove to create a surface pattern; Optionally, polishing and / or any other final treatment to deburr and / or round off any sharp scallops between the grooves.

[0008] These grooves achieve a narrow contact area between the chips discharging through the chip pocket during milling and the front wall of the chip pocket. This also reduces the risk of friction and resulting chip jamming, allowing the chips to flow smoothly over the surface pattern. Because the first and second grooves intersect, the risk of chips rubbing against protrusions / ridges between the grooves is reduced compared to surface patterns with non-intersecting grooves separated by continuous ridges. Furthermore, because the first and second grooves intersect, when coolant / lubricant is applied to the tool and cutting area via an external arrangement or via internal coolant channels located within the tool body during wet machining, the distribution of coolant / lubricant on the wall surface is improved, allowing the chips to flow smoothly over the surface pattern.

[0009] The tool body may be provided with one or more internal coolant channels with outlets in the wall surface, and / or in a surface associated with the insert seat, and / or at the front end of the tool body. If the outlet or coolant channel is located at the front end of the tool body, or if the outlet or coolant channel is located so as to direct the coolant sprayed onto the cutting insert seated on the insert seat, and if the coolant / lubricant is applied via an external arrangement, the coolant / lubricant will splash onto the wall surface of the chip pocket, achieving the described effect. Preferably, the coolant channel outlet is located in a portion of the wall surface having the surface pattern.

[0010] The grooves may be formed using a ball nose milling tool to create a concave groove profile and scallops between adjacent grooves. The grooves may also have transition surfaces between two adjacent first grooves and / or two adjacent second grooves. When the grooves are formed, the front wall surface of the chip pocket may be polished to round off sharp scallops and / or sharp edges, and / or remove any burrs that may be present, and / or achieve a smooth surface finish. Polishing is not the only method that can be used. Other methods, such as blasting and shot peening, or any other method that rounds off sharp scallops, may also be used. Deburring processes, such as thermal deburring, may also be used. A combination of these methods may also be used to round off sharp scallops and / or remove burrs and / or create desired characteristics of the wall surface and / or wall surface material. A coating, preferably a wear-resistant coating, may also be applied to the wall surface.

[0011] The term "concave groove profile" as used herein refers to a groove surface having a concave shape as seen in a cross-sectional view taken along a plane perpendicular to the longitudinal extension of the groove. The shape of the concave groove profile may preferably be, but is not necessarily, the same or essentially the same (i.e., within manufacturing tolerances) for all of the first grooves and / or all of the second grooves, respectively. Preferably, all of the grooves, including the first grooves and the second grooves, have the same or essentially the same shape of the concave groove profile.

[0012] These surface patterns allow for more cost-effective machining of chip pockets. In conventional tool bodies, i.e., tool bodies with uniform walls or surface patterns with non-intersecting grooves separated by continuous ridges, the walls must have specific surface characteristics to avoid the risk of chip jamming. These surface requirements adversely affect the economics of the process and the final milling tool prize. For example, to achieve wall surfaces that meet the required surface finish, cutting data must be kept low and a final, expensive finishing operation must be included. At the same time, wear on the tools used to machine the chip pockets must be monitored and kept low, which often leads to short tool replacement cycles. However, the proposed tool body surface patterns reduce machining time, both during the initial manufacturing step when the chip pocket space is created, as well as during the finishing operation, i.e., during groove machining. This is due to the use of the front end of the ball nose milling tool to generate the grooves. The thin chips generated by the ball nose milling tool allow for high cutting data and a beneficial force direction acting on the ball nose milling tool.

[0013] According to one embodiment, for each of the first grooves and / or each of the second grooves, as viewed in a cross section perpendicular to the longitudinal extension of the groove, the concave groove profile extends between a first end point and a second end point, a first tangent to the concave groove profile at the first end point and a second tangent to the concave groove profile at the second end point intersect below the concave groove profile, and an angle δ formed by the first tangent and the second tangent is such that 90°≦δ≦175°, preferably 110°≦δ≦170°. Within this angle interval, the grooves are relatively shallow and wide, especially when the concave groove profile has the shape of a circular or elliptical arc. This means that the risk of chip blockage in the groove is minimized.

[0014] According to one embodiment, the first grooves are arranged so that two adjacent first grooves are immediately adjacent to one another. As seen in a cross-sectional view perpendicular to the longitudinal extension of the first grooves, each of the two adjacent first grooves may be connected by a convexly rounded portion having a relatively small radius of curvature compared to the radius of curvature of the concave groove profile, such as a scallop formed using a ball-nose milling tool and subsequently polished during milling. The proximity of the grooves reduces friction during chip evacuation. The second grooves may also be immediately adjacent to one another, or alternatively, they may be separated by a distance to form a ridge extending along the first groove.

[0015] According to one embodiment, the concave groove profile is arc-shaped. This arc may preferably be a circular arc. This is easily produced using a ball nose milling tool. The concave profile may also have the shape of an elliptical arc, or a parabola, a portion of a parabola, or a similar shape. Such a profile can be approximated by a circular arc, with the value of the angle δ at which the approximate profile is invariant. A ball nose milling tool may have a front portion capable of producing an elliptical arc profile or a parabolic shape, or the like, from which such a profile can also be produced.

[0016] According to one embodiment, the radius of curvature or approximate radius of curvature of the arc-shaped concave groove profile is in the range of 1 to 6 mm.

[0017] According to one embodiment, the radius of curvature or an approximate radius of curvature of the concave groove profile of the first groove is equal to the radius of curvature or an approximate radius of curvature (within manufacturing tolerances) of the concave groove profile of the second groove, which is preferred because it allows the first and second grooves to be formed using the same ball nose milling tool.

[0018] According to one embodiment, the wall surface includes a front wall surface facing the insert sheet, and the surface pattern covers at least a portion of the front wall surface, preferably a major portion of the front wall surface, more preferably the entire front wall surface, more preferably a major portion of the wall surface, and even more preferably the entire wall surface.

[0019] According to one embodiment, the surface pattern includes a plurality of protrusions formed between the first groove and the second groove, each of which is separated by two adjacent first grooves and two adjacent second grooves. The protrusions are understood here to protrude relative to the bottom level of the grooves. If the surface pattern is formed using a ball-nose milling tool, the protrusions may be in the form of scallops created when milling the grooves. Preferably, the surfaces are polished to round off sharp scallops and / or sharp edges. Preferably, all of the surfaces of each of the protrusions form parts of the first groove and the second groove that are or may be polished later. If the grooves are relatively close to each other, such as immediately adjacent, each of the protrusions has a base in the form of a parallelogram and four rounded side faces that converge to a point-like (rounded) apex of the protrusion. Each of the side faces forms part of the first and second grooves. If the grooves are not relatively close to each other, the protrusions may have a top plateau instead of a point-like apex. The top plateau is bounded by four rounded sides that converge to the top plateau. In such cases, the top plateau is in the form of a parallelogram with its largest side less than 3 mm. The pointed apex and / or edges and / or sides and / or plateau of the protrusions may be polished to round them. As described above, other post-processing may also be used. The form and shape of the protrusions may vary across the wall of the chip pocket.

[0020] According to one embodiment, each of the protrusions forms a ridge extending along the first groove. In this case, the distance between the second grooves may be greater than the distance between the first grooves, and / or the second grooves may be shallower than the first grooves. The length of the ridge is determined by the distance between the second grooves and the depth and curvature of the second grooves. If the preferred distance between the second grooves is less than 3 mm, the length of the ridge is at least less than 3 mm.

[0021] According to one embodiment, each of the protrusions has a rounded apex, as viewed in a cross section perpendicular to the longitudinal extension of the first or second groove. This may be achieved, for example, by grinding or any other post-treatment as described above. The rounded apex reduces friction during chip evacuation.

[0022] According to one embodiment, the first grooves are spaced apart by a first distance d1 of 0.5 to 3 mm, and / or the second grooves are spaced apart by a second distance d2 of 0.5 to 3 mm. The first distance may be equal to the second distance, or the second distance may be different from the first distance. The first distance may be the same within a set of first grooves so that the first grooves are evenly spaced. However, because the walls on which the grooves are formed are often curved, the first distance may vary slightly within a set of first grooves, and correspondingly within a set of second grooves.

[0023] According to one embodiment, in at least a portion of the front wall, the first grooves are parallel to one another and / or the second grooves are parallel to one another. Preferably, at least adjacent first grooves and / or adjacent second grooves are parallel or essentially parallel to one another.

[0024] According to one embodiment, in a planar or essentially planar wall section, the second grooves extend at an angle α relative to the first grooves, the angle α being in the range of 30 to 90°, preferably 60 to 90°.

[0025] According to one embodiment, the maximum depth of the first and / or second grooves is in the range of 0.03 to 0.20 mm, preferably 0.05 to 0.15 mm. Preferably, the ratio between the depth and the distance between the grooves is in the range of 0.020 to 0.20 for both the first and second grooves.

[0026] The present invention also relates to a milling tool comprising the tool body as presented and at least one cutting insert mounted in at least one insert seat. Advantages and preferred features of such a milling tool can be seen from the above description of the tool body.

[0027] Further preferred features and advantages of the present invention will be seen from the detailed description that follows.

[0028] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a perspective view schematically showing a milling tool according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view schematically showing a part of a surface pattern of a tool body according to an embodiment of the present invention. [Figure 3] FIG. 3 is a top view showing the surface pattern of FIG. [Figure 4] FIG. 4 is a perspective view showing a partially generated surface pattern such as that of FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a photograph showing a tool body according to another embodiment of the present invention. [Figure 7] FIG. 7 is a scanned image of the wall of the tool body of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0030] A milling tool 1 including a tool body 2 according to an embodiment of the invention is shown schematically in Figure 1, and a tool body 2 according to another embodiment is shown in Figure 6. In both embodiments, the tool body 2 includes a front end 3 and a rear end 4. Extending therebetween are a central axis C and a peripheral envelope surface 5. The tool body 2 is configured to be turned in a direction of rotation R about the central axis C.

[0031] A plurality of insert seats 6 are formed at the transition between the front end 3 and the peripheral envelope surface 5. Each of the insert seats 6 is configured to support a cutting insert 7 adapted to be placed therein. A chip pocket 8 is provided in front of each of the insert seats 6 in the direction of rotation R. The chip pocket 8 is bounded by walls 9, including a front wall 10 facing the insert seat 6 in the direction of rotation R. The cutting insert 7 is adapted to be fixed to the insert seat 6 using a fixing member 11, here in the form of a screw. When viewed along the central axis C toward the front end 3, the chip pocket 8 of the milling tool 1 of FIG. 1 is substantially U-shaped. However, the chip pocket may be more open or have other shapes.

[0032] The wall surface 9 is curved and is preferably covered with a surface pattern formed by ball nose milling followed by grinding. The surface pattern is shown in more detail in Figures 2 to 5, where the surface pattern is shown in plan view.

[0033] Due to the curved nature of the wall 9, the surface pattern is formed by a plurality of first grooves 12, 12a-e, which extend parallel or essentially parallel to a first longitudinal extension line L1 on at least a portion of the front wall 10, and a plurality of second grooves 13, 13a-e, which extend parallel or essentially parallel to a second longitudinal extension line L2 on at least a portion of the front wall 10. For example, each of two adjacent first grooves 12, such as grooves 12a and 12b, or each of two adjacent second grooves 13, such as grooves 13a and 13b, may extend essentially parallel, while a first groove 12 located at an opposite end of the wall 9 may have non-parallel extension lines due to the curved wall 9. The second grooves 13 intersect the first grooves 12 and extend at an angle α relative to the first grooves 12. In the embodiment shown, α=37°. Each of the first grooves 12 and each of the second grooves 13 has a concave groove profile 17. In other words, in a cross-sectional view perpendicular to the first longitudinal extension line L1 of one of the first grooves 12, the surface of the first groove 12 may be described as a concave curved surface. In the embodiment shown here, the first and second grooves 12 and 13 have identically formed concave groove profiles 17. Here, the concave groove profile 17 may be described by a circular arc with a radius of curvature R1 (first groove 12) = R2 (second groove 13) = 1.5 mm.

[0034] The first grooves 12 are arranged so that two adjacent first grooves 12a and 12b are immediately adjacent to each other. This can be clearly seen in FIG. 4, which shows a surface pattern that is only partially formed and includes three first grooves 12a, 12b, and 12c and three intersecting second grooves 13a, 13b, and 13c. While adjacent first grooves 12a and 12b are immediately adjacent, adjacent second grooves 13b and 13c have flat upper surfaces and are separated by ridges 18 that extend along the second grooves 13b and 13c. The first grooves 12 are equally spaced apart at a first distance d1 = 1.1 mm (see FIG. 3) and have a depth h1 = 0.11 mm (see FIG. 5). The second grooves 13 are equally spaced at a second distance d2=1.8 mm (see FIG. 3) and have a depth h2=0.10 mm (not shown), i.e., slightly shallower than the first grooves 12. The depths h1 and h2 may vary within the surface pattern.

[0035] The protrusions 14, 14a-c, are separated by two adjacent first grooves 12 and two adjacent second grooves 13. For example, as shown in FIG. 3, protrusion 14b is separated by first grooves 12b and 12c and second grooves 13b and 13c. As seen in a cross-sectional view perpendicular to the first longitudinal extension line L1 of one of the first grooves 12 (see FIG. 5), each of the protrusions 14 is convexly rounded with a relatively small radius of curvature R1, which in the illustrated embodiment is 0.08 mm, compared to the 1.5 mm radius of curvature R1 of the concave groove profile. Each of the protrusions 14 forms a ridge with a flat upper surface extending in the first longitudinal direction L1. The ridge is bent on each side by the second grooves 13 and, in the illustrated embodiment, has a length of approximately 0.5 mm in the first longitudinal direction L1.

[0036] The milling tool 1 is provided with a system of internal coolant channels, at least one of which has at least one outlet 20 in the chip pocket 8. The system of internal coolant channels can be of any known kind.

[0037] As seen in the cross-sectional view of FIG. 5 , perpendicular to one longitudinal extension line L1 of the first groove 12d, the concave groove profile 17 extends between a first end point 15 and a second end point 16. A first tangent line z1 to the concave groove profile at the first end point 15 and a second tangent line z2 to the concave groove profile at the second end point 16 intersect below the concave groove profile 17. The angle δ formed by the first tangent line z1 and the second tangent line z2 is such that 90°≦δ≦175°, preferably 110°≦δ≦170°. In the embodiment shown, δ=136°. A corresponding angle may also be defined for the second groove 13 (not shown).

[0038] For the first groove 12, the angle δ may be defined as follows: TIFF0007827408000001.tif25170h 1c is the depth of the concave profile, which is equal to h1 before polishing. After polishing, h 1c is smaller than h1 because it does not include the height of the convexly rounded portion.

[0039] FIG. 7 shows a scanned image of a portion of the wall surface 9 of the tool body 2 shown in FIG.

[0040] The tool body 2 may be manufactured using a method including: providing a tool body blank; removing material from a tool body blank with a first tool to create a space forming a chip pocket (8); Processing the insert sheet 6; machining first grooves 12, 12a-e in the wall 9 of the chip pocket 8 using a first ball nose milling cutter; machining second grooves 13, 13a-e into the wall 9 of the chip pocket 8 using a second ball nose milling cutter, preferably the same milling cutter as the first ball nose milling cutter, such that the second grooves 13, 13a-e intersect with the first grooves 12, 12a-e to create a surface pattern; Preferably, but not necessarily, by polishing and / or any other final treatment to deburr and / or round off any sharp scallops between grooves 12, 12a-e, 13, 13a-e.

[0041] Machining the insert sheet 6 may be done either before or after machining the grooves.

[0042] During machining of a workpiece using the milling tool 1 shown in Figure 1, chips are removed from the workpiece by the cutting edge of the cutting insert 7 and strike the front wall surface 10 of the chip pocket 8 during evacuation from the working area. The surface pattern reduces the contact area between the chip and the front wall surface 10. Friction that occurs as the chip moves upward along the front wall surface 10 is also reduced as a result, achieving smooth chip evacuation and minimizing the risk of chip jamming.

[0043] The present invention is, of course, not limited to these disclosed embodiments, and variations and modifications are possible within the scope of the following claims. For example, the shape of the cutting insert may vary, as may the number of insert seats in the tool body. The surface pattern may be formed only on a portion of the wall surface, such as only on the front wall surface or only on a portion of the front wall surface.

Claims

1. A tool body (2) for a milling tool (1), comprising: a front end (3) and a rear end (4) between which a central axis (C) and a peripheral envelope surface (5) extend, the tool body (2) being configured to be rotated in a direction of rotation (R) about the central axis (C); at least one insert seat (6) formed at the transition between the front end (3) and the peripheral envelope surface (5), the at least one insert seat (6) configured to support a cutting insert (7) adapted to be placed on the insert seat (6); a chip pocket (8) located in front of the insert seat (6) in the direction of rotation (R), the chip pocket (8) being bounded by a wall (9), A surface pattern including a plurality of first grooves (12, 12a to e) and a plurality of second grooves (13, 13a to e) is formed on at least a portion of the wall surface (9), the second grooves (13, 13a to e) intersect with the first grooves (12, 12a to e), and each of the first grooves (12, 12a to e) and / or each of the second grooves (13, 13a to e) is aligned with an extension line (L 1 , L 2 ) of the length direction of the grooves (12, 12a to e, 13, 13a to e) for each of the first grooves (12, 12a to e) and / or each of the second grooves (13, 13a to e).

1. A tool body (2) for a milling tool (1), characterized in that, in a cross section perpendicular to the plane of the milling tool (1), the tool body (2) has a concave groove profile (17) extending between a first end point (15) and a second end point (16), the concave groove profile (17) being arc-shaped.

2. A tool body as described in claim 1, wherein a first tangent (z1) to the concave groove profile (17) at the first end point (15) and a second tangent (z2) to the concave groove profile (17) at the second end point (16) intersect below the concave groove profile (17), and an angle δ formed by the first tangent (z1) and the second tangent (z2) is 90°≦δ≦175°, preferably 110°≦δ≦170°.

3. 3. A tool body according to claim 1 or 2, wherein the first grooves (12, 12a-e) are arranged such that two adjacent first grooves (12, 12a-e) are immediately adjacent to each other.

4. Tool body according to any one of claims 1 to 3, wherein the radius of curvature (R1, R2) or an approximate radius of curvature of the arc-shaped concave groove profile (17) is in the range of 1 to 6 mm.

5. 5. The tool body according to claim 1, wherein the radius of curvature (R1) of the concave groove profile (17) of the first groove (12, 12a-e) is equal to the radius of curvature (R2) of the concave groove profile (17) of the second groove (13, 13a-e).

6. 6. A tool body according to any one of claims 1 to 5, wherein the wall (9) includes a front wall (10) facing the insert seat, and the surface pattern covers at least a portion of the front wall (10), preferably a major portion of the front wall (10), more preferably the entire front wall (10), more preferably a major portion of the wall (9), and even more preferably the entire wall (9).

7. 7. A tool body according to any one of claims 1 to 6, wherein the surface pattern comprises a plurality of protrusions (14, 14a to d) formed between the first grooves (12, 12a to e) and the second grooves (13, 13a to e), each of the protrusions (14, 14a to d) being separated by two adjacent first grooves (12, 12a to e) and two adjacent second grooves (13, 13a to e).

8. 8. A tool body according to claim 7, wherein each of said projections (14, 14a-d) forms a ridge extending along said first groove (12, 12a-e).

9. 9. A tool body according to claim 7 or 8, wherein each of the protrusions (14) has a rounded apex as seen in a cross section perpendicular to a longitudinal extension (L1, L2) of the first or second groove (12, 12a-e, 13, 13a-e).

10. 10. A tool body according to any one of claims 1 to 9, wherein the first grooves (12, 12a-e) are spaced apart by a first distance d1 of 0.5 to 3 mm and / or the second grooves (13, 13a-e) are spaced apart by a second distance d2 of 0.5 to 3 mm.

11. 11. A tool body according to any one of claims 1 to 10, wherein in at least one portion of the wall (9), preferably in one portion of the front wall (10), the first grooves (12, 12a-e) are parallel to one another and / or the second grooves (13, 13a-e) are parallel to one another.

12. 12. A tool body according to any one of claims 1 to 11, wherein in a planar or essentially planar wall section the second grooves (13, 13a-e) extend at an angle α to the first grooves (12, 12a-e), said angle α being in the range of 30 to 90°, preferably 60 to 90°.

13. 13. A tool body according to any one of the preceding claims, wherein the maximum depth of the first groove (12, 12a-e) and / or the second groove (13, 13a-e) is in the range of 0.03 to 0.20 mm, preferably 0.05 to 0.15 mm.

14. A milling tool (1) comprising the tool body (2) according to any one of claims 1 to 13 and at least one cutting insert (7) mounted on the at least one insert seat (6).

15. A method for manufacturing a tool body (2) according to any one of claims 1 to 13, comprising the steps of: providing a tool body blank; removing material from the tool body blank with a first tool to create a space forming the chip pocket (8); Processing the insert sheet (6); generating said first grooves (12, 12a-e) in said wall surface (9) using a first ball nose milling cutter; - creating the second grooves (13, 13a-e) in the wall surface (9) using a second ball nose milling cutter, preferably the same milling cutter as the first ball nose milling cutter, such that the second grooves (13, 13a-e) intersect with the first grooves (12, 12a-e) to create a surface pattern; Optionally, polishing and / or any other final treatment to deburr and / or round off sharp scallops between said grooves (12, 12a-e, 13, 13a-e).

Images