Rotating cutting tool with high-pressure resistant coolant cap and coolant cap

Abstract

Rotating cutting tool (10), comprising: a base body (12) with a recessed surface (22) formed in an end face (12a) of the base body (12), wherein the recessed surface (22) has a retaining ring notch (22d) formed therein; a fastening screw (15) by means of which the base body (12) is attached to a rotatable shaft, a shaft adapter or a spindle of a milling machine, wherein the fastening screw (15) has a central opening (15a), a coolant cap (14) arranged within the recessed surface (22) of the base body (12), wherein the coolant cap (14) has an outer surface (26), an inner surface (28) and a cylindrical outer surface (29) extending between the outer surface (26) and the inner surface (28); and a retaining ring (20) arranged within the retaining ring notch (22d) of the base body (12) to detachably attach the coolant cap (14) to the base body (12), wherein the outer surface (26) of the coolant cap (14) contacts the retaining ring (20) when coolant under high pressure is introduced into the base body (12), a coolant chamber (38) connected to the central opening 15a of the fastening screw (15), wherein the coolant chamber (38) is formed by the fastening screw (15), the base body (12) and the inner surface (28) of the coolant cap (14), wherein the inner surface (28) of the coolant cap (14) is arranged in a distance relationship with respect to the fastening screw (15) and the base body (12), whereby coolant under high pressure flows through the central opening (15a) into the coolant chamber (38) and is directed radially outwards to the vicinity of the cutting inserts (18) attached to the base body (12).

Description

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

[0001] The invention relates to the field of rotating cutting tools. In particular, the invention relates to a rotating cutting tool with a high-pressure-resistant coolant cap for delivering a high-pressure coolant flow near the cutting inserts attached to the base body, as well as to a coolant cap for a rotating cutting tool. DESCRIPTION OF RELATED TECHNOLOGY

[0002] Milling cutters for milling operations are well known. Such cutters typically comprise a base body, which is a generally circular ring with several pockets in its outer circumference. A cutting insert is mounted in each pocket. Each cutting insert comprises a body and at least one cutting edge. The body is mounted directly in the pocket or to a milling cartridge mounted in the pocket.

[0003] In the past, it was common practice to deliver cutting fluid to the cutting tool's cutting inserts through channels drilled into the cutting tool body. Attaching a coolant cap to the body is typically accomplished using multiple threaded fasteners, such as screws and the like, that are threaded into the body. However, it has been discovered that the threaded fasteners can fail when a high-pressure coolant stream is applied to the cutting tool, resulting in coolant leakage between the coolant cap and the body.

[0004] Such cutting tools with a coolant device are described in WO 2010 / 128 930 A1, EP 2 517 815 A1, US 2012 / 0 230 781 A1 and US 2008 / 0 175 677 A1.

[0005] Accordingly, there is a need in the art for an improved cutting tool capable of delivering a high pressure coolant stream near the cutting inserts. SUMMARY OF THE INVENTION

[0006] The task of delivering a coolant flow under high pressure to the vicinity of cutting inserts attached to the base body is solved by creating a coolant cap with a retaining ring for attaching the coolant cap to the base body.

[0007] According to one aspect of the invention, a cutting tool comprises a base body having a recessed surface formed in an end face of the base body. The recessed surface has a retaining ring notch formed therein. The base body is attached to a rotatable shaft, shaft adapter, or spindle of a milling machine by a mounting screw. The mounting screw has a central opening. A coolant cap is disposed within the recessed surface of the base body. The coolant cap has an outer surface, an inner surface, and a cylindrical outer surface extending between the outer surface and the inner surface. A retaining ring is disposed within the retaining ring notch of the base body to removably secure the coolant cap to the base body.The outer surface of the coolant cap contacts the retaining ring when high-pressure coolant is introduced into the body. A coolant chamber communicates with the central opening of the retaining screw. The coolant chamber is formed by the retaining screw, the body, and the inner surface of the coolant cap. The inner surface of the coolant cap is spaced apart from the retaining screw and the body. This allows high-pressure coolant to flow through the central opening into the coolant chamber and be directed radially outward toward the cutting inserts attached to the body.

[0008] According to another aspect of the invention, a coolant cap for a cutting tool comprises an outer surface, an inner surface, and a cylindrical outer surface extending between the outer surface and the inner surface. The outer surface of the coolant cap contacts a retaining ring when high-pressure coolant is introduced into a base body to removably secure the coolant cap to the base body. The inner surface of the coolant cap has a flat lower inner surface, an arcuate inner surface extending radially outward with respect to the lower inner surface, and a flat upper inner surface extending radially outward from the arcuate inner surface to the cylindrical outer surface (29). The cylindrical outer surface has a first cylindrical outer surface portion having an outer diameter and a notch formed therein.A sealing element is accommodated in the notch, which prevents leakage of coolant under high pressure between the base body and the coolant cap. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Although various embodiments of the invention are illustrated, the specific embodiments shown are not to be construed as limiting the claims. It is understood that various changes and modifications may be made without departing from the scope of this invention. Fig. 1 is an exploded isometric view of a cutting tool having a base body, a coolant cap, and a retaining ring for releasably securing the coolant cap to the base body according to one embodiment of the invention; Fig. 2 is an isometric view of the cutting tool of Fig. 1 in assembled condition, with the coolant cap releasably secured to the base body by means of the retaining ring; Fig. Figure 3 is a cross-sectional view of the cutting tool in assembled condition with the coolant cap, taken along line 3-3 in Fig. 2; Fig. 4 is an enlarged, partial cross-sectional view of the retaining ring of Fig. 3 coolant cap detachably attached to the base body, showing the coolant chamber between the coolant cap and the base body; Fig. 5 is an isometric front view of the coolant cap according to an embodiment of the invention; Fig. 6 is an isometric rear view of the coolant cap according to an embodiment of the invention; Fig. 7 is a plan view of the coolant cap and Fig. Figure 8 is a cross-sectional view of the coolant cap, taken along line 8-8 in Fig. 7. DETAILED DESCRIPTION OF THE INVENTION

[0010] With reference to Fig. 1 to 4, wherein like reference numerals designate like components throughout the several figures, there is illustrated a rotating cutting tool 10 according to a preferred embodiment of the invention. In the illustrated embodiment, the rotating cutting tool 10 comprises a milling cutter. Generally, the milling cutter 10 includes a base body 12, a coolant cap 14 provided at the center of the base body 12 for efficiently directing a flow of high-pressure coolant from the base body 12, and a retaining ring 20 for releasably securing the coolant cap 14 to the base body 12.

[0011] Typically, a fastening screw 15 is used to secure the base body 12 to a rotatable shaft, shaft adapter, or spindle of a milling machine (not shown). Optionally, the fastening screw 15 may be replaced by other means for securing the base body 12 to the milling machine, such as threaded fasteners and the like. The fastening screw 15 is arranged about a rotational axis 16 of the cutter 10, which coincides with the rotational axis of the milling machine to which the cutter 10 is attached. The fastening screw 15 has a central opening 15a to allow the coolant to flow. The base body 12 also has a plurality of insert-receiving pockets 17 continuously formed on the outer peripheral surface of the base body 12. Each of the pockets 17 has a predetermined size.

[0012] Cutting inserts 18, made of, for example, high speed steel, powder metal, carbides, or ceramic, are each continuously held in the pockets 17 without interruption or gaps therebetween. As shown in the illustrated embodiment, a total of eight (8) cutting inserts 18 are mounted in the base body 12. It should be understood, however, that the invention is not limited by the number of cutting inserts 18 mounted on the base body 12, and that the principles of the invention may be applied to a base body 12 to which any desired number of cutting inserts 18 may be isometrically and / or tangentially mounted.

[0013] As in the Fig. 3 and Fig. 4, the base body 12 further includes a generally circular recessed surface 22 formed in an end face 12a of the base body 12. As shown in Fig. 3, the recessed surface 22 includes a bottom surface 22a, a first cylindrical surface 22b extending axially (in the direction of the rotation axis 16 or x-axis) from the bottom surface 22a to the end surface 12a, and a second cylindrical surface 22c extending radially outward (in the direction perpendicular to the rotation axis 16 or x-axis) relative to the first cylindrical surface 22b to the end surface 12a. The second cylindrical surface 22c has a retaining ring notch 22d formed therein. In addition, the recessed surface 22 includes an arcuate inner surface 22e extending radially inward relative to the bottom surface 22a and a fastening screw seating surface 22f extending radially inward relative to the arcuate inner surface 22e.

[0014] In the illustrated embodiment, the lower surface 22a, the first cylindrical surface 22b, the second cylindrical surface 22c, the retaining ring notch 22d, the arcuate inner surface 22e and the fastening screw seat surface 22f are arranged concentrically about the central axis 16.

[0015] Referring to the Fig. 5-8, the coolant cap 14 is generally circular and preferably made of steel so that it is capable of withstanding a high-pressure coolant. Here, a high-pressure coolant is understood to mean a coolant having a pressure between about 6205 kPa (900 psi (62.0 bar)) and about 20684 kPa (3000 psi (206.8 bar)). The coolant cap 14 has a generally planar outer surface 26, an inner surface 28, a cylindrical outer surface 29 extending between the outer surface 26 and the inner surface 28, and a central axis 30.

[0016] The outer surface 26 of the coolant cap 16 has a substantially planar upper outer surface 26a, an arcuate outer surface 26b extending radially outward relative to the upper outer surface 26a, and a substantially planar lower outer surface 26c extending radially outward from the arcuate outer surface 26b to the cylindrical outer surface 29. The upper outer surface 26a, the arcuate outer surface 26b, and the lower outer surface 26c are arranged concentrically about the central axis 30 of the coolant cap 14.

[0017] The inner surface 28 of the coolant cap 14 includes a substantially planar lower inner surface 28a and an arcuate inner surface 28b extending radially outward relative to the lower inner surface 28a, and a planar upper inner surface 28c extending radially outward from the arcuate inner surface 28b to the cylindrical outer surface 29. The lower inner surface 28a, the arcuate inner surface 28b, and the upper inner surface 28c are concentrically disposed about the central axis 30 of the coolant cap 14. It should be noted that the central axis 30 of the coolant cap 14 is substantially aligned and parallel to the central axis 16 of the base body 12 when the coolant cap 14 is attached to the base body 12.

[0018] As in Fig. 8, the cylindrical outer surface 29 of the coolant cap 14 has a first cylindrical outer surface portion 29a extending axially (in the direction of the central axis 30 or x-axis) from the inner surface 28. The first cylindrical outer surface portion 29a, having an outer diameter D1, has a notch 31 formed therein. The notch 31 is configured to receive a sealing element 34, such as an O-ring and the like ( Fig. 3 and Fig. 4). The sealing element 34 serves to prevent leakage of the high-pressure coolant between the base body 12 and the coolant cap 14. The cylindrical outer surface 29 also has a second cylindrical outer surface portion 29b. The second cylindrical outer surface portion 29b has an outer diameter D2 that is larger than the outer diameter D1 of the first cylindrical outer surface portion 29a. It should be noted that the outer diameter D1 of the first cylindrical outer surface portion 29a and the outer diameter D2 of the second cylindrical outer surface portion 29b are slightly smaller than the outer diameters of the first cylindrical surface 22b and the second cylindrical surface 22c, respectively, of the recessed surface 22 of the base body 12, so that the coolant cap 14 is in a snug fit when, as shown in the Fig. 3 and Fig. 4, is arranged within the base body 12.

[0019] Referring again to Fig. 3, the coolant cap 14 is detachably attached to the base body 12 such that the lower inner surface 28a of the coolant cap 14 is disposed in a spaced relationship with respect to the fastening screw 15. Similarly, the arcuate inner surface 28b of the coolant cap 14 is disposed in a spaced relationship with respect to the arcuate inner surface 22e of the recessed surface 22 of the base body 12. Furthermore, the upper inner surface 28c of the coolant cap 14 is disposed in a spaced relationship with respect to the lower surface 22a of the recessed surface 22 of the base body 12. This spaced relationship between the base body 12, the fastening screw 15, and the coolant cap 14 forms a coolant chamber 38 through which a high-pressure coolant, such as a fluid and the like, is supplied from the spindle of a milling machine (not shown) to the vicinity of the cutting inserts 18.In particular, the high-pressure coolant is passed through the central opening 15a of the fastening screw 15 and flows in the direction of the arrows through the coolant chamber 38 and into a plurality of coolant openings 40 formed in the base body 12 (for the sake of clarity, . Fig. 3 only one coolant opening 40 is shown). The coolant openings 40 efficiently direct the high-pressure coolant from the coolant chamber 38 radially outward into the vicinity of the cutting inserts 18.

[0020] When high-pressure coolant is introduced into the base body 12, the outer surface 26 of the coolant cap 14 is pressed against the end surface 12a of the base body 12 so that the outer surface 26, and in particular the lower outer surface 26c of the coolant cap 14, contacts the retaining ring 20 to releasably secure the coolant cap 14 to the base body 12. A simulation using finite element analysis (FEM) has shown that the coolant cap 14 of the invention is capable of delivering high-pressure coolant (i.e., coolant having a pressure between about 6205 kPa (900 psi (62.0 bar)) and about 20684 kPa (3000 psi (206.8 bar)) without loss due to leakage due to a failure of the coolant cap 14. Accordingly, the coolant cap 14 of the invention is better able to deliver high-pressure coolant to the vicinity of the cutting inserts 18 than conventional coolant caps.

[0021] The patents and publications referred to in this document are to be considered incorporated herein by reference.

[0022] Although preferred embodiments have been described herein, the invention may be embodied otherwise within the scope of the appended claims.

Claims

[1] Rotating cutting tool (10), comprising: a base body (12) having a recessed surface (22) formed in an end face (12a) of the base body (12), the recessed surface (22) having a retaining ring notch (22d) formed therein; a fastening screw (15) by means of which the base body (12) is fastened to a rotatable shaft, a shaft adapter or a spindle of a milling machine, wherein the fastening screw (15) has a central opening (15a), a coolant cap (14) arranged within the recessed surface (22) of the base body (12), the coolant cap (14) having an outer surface (26), an inner surface (28), and a cylindrical outer surface (29) extending between the outer surface (26) and the inner surface (28); and a retaining ring (20) disposed within the retaining ring notch (22d) of the base body (12) for removably securing the coolant cap (14) to the base body (12), wherein the outer surface (26) of the coolant cap (14) contacts the retaining ring (20) when high-pressure coolant is introduced into the base body (12), a coolant chamber (38) communicating with the central opening 15a of the fastening screw (15), the coolant chamber (38) being formed by the fastening screw (15), the base body (12) and the inner surface (28) of the coolant cap (14), wherein the inner surface (28) of the coolant cap (14) is arranged in a spaced relationship with respect to the fastening screw (15) and the base body (12), whereby coolant under high pressure flows through the central opening (15a) into the coolant chamber (38) and is directed radially outward into the vicinity of the cutting inserts (18) attached to the base body (12). [2] A rotary cutting tool according to claim 1, wherein the outer surface (26) of the coolant cap (14) has a planar upper outer surface (26a), an arcuate outer surface (26b) extending radially outward with respect to the upper outer surface (26a), and a planar lower outer surface (26c) extending radially outward from the arcuate outer surface (26b) to the cylindrical outer surface (29). [3] A rotating cutting tool according to claim 2, wherein the retaining ring (20) contacts the planar lower outer surface (26c) when high pressure coolant is introduced into the base body (12). [4] A rotary cutting tool according to any one of the preceding claims, wherein the inner surface (28) of the coolant cap (14) has a planar lower inner surface (28a), an arcuate inner surface (28b) extending radially outwardly with respect to the lower inner surface (28a), and a planar upper inner surface (28c) extending radially outwardly from the arcuate inner surface (28b) to the cylindrical outer surface (29). [5] A rotary cutting tool according to any one of the preceding claims, wherein the recessed surface (22) comprises a lower surface (22a), a first cylindrical surface (22b) extending axially from the lower surface (22a) to an end surface (12a) of the base body (12), and a second cylindrical surface (22c) extending radially outwardly from the first cylindrical surface (22b) to the end surface (12a). [6] A rotary cutting tool according to claim 5, wherein the recessed surface (22) further comprises an arcuate inner surface (22e) extending radially inward with respect to the lower surface (22a), and a fastening screw seating surface (22f) extending radially inward with respect to the arcuate inner surface (22e). [7] A rotary cutting tool according to any one of the preceding claims, wherein the inner surface (28) of the coolant cap (14) further comprises a substantially planar lower inner surface (28a), an arcuate inner surface (28b) extending radially outwardly with respect to the lower inner surface (28a), and an upper inner surface (28c) extending radially outwardly from the arcuate inner surface (28b) to the cylindrical outer surface (29). [8] Rotating cutting tool according to one of the preceding claims, wherein the base body (12) comprises coolant openings (40) which are in communication with the coolant chamber (38) and which direct high-pressure coolant into the vicinity of cutting inserts (18). [9] A rotary cutting tool according to any one of the preceding claims, wherein the cylindrical outer surface (29) of the coolant cap (14) comprises a first cylindrical outer surface portion (29a) extending axially from the inner surface (28) and having a notch (31) formed therein, and a second cylindrical outer surface portion (29b) extending axially between the first cylindrical outer surface portion (29a) and the outer surface (26), wherein an outer diameter (D2) of the second cylindrical outer surface portion (29b) is greater than an outer diameter (D1) of the first cylindrical outer surface portion (29a). [10] A rotary cutting tool according to any one of the preceding claims, wherein the recessed surface (22) has a bottom surface (22a), an arcuate inner surface (22e) extending radially inward with respect to the bottom surface (22a) of the recessed surface (22), and a fastening screw seating surface (22f) extending radially inward with respect to the arcuate inner surface (22e) of the recessed surface (22). [11] A rotary cutting tool according to claim 10, wherein the lower inner surface (28a) of the coolant cap (14) is arranged in a spaced relationship with respect to the fastening screw (15), wherein the arcuate inner surface (28b) of the coolant cap (14) is arranged in a spaced relationship with respect to the arcuate inner surface (22e) of the recessed surface (22), and wherein the upper inner surface (28c) of the coolant cap (14) is arranged in a spaced relationship with respect to the lower surface (22a) of the recessed surface (22). [12] Rotating cutting tool according to one of the preceding claims, wherein the cylindrical outer surface (29) of the coolant cap (14) has a first cylindrical outer surface portion (29a) with an outer diameter (D1) and a notch (31) formed therein, wherein a sealing element (34) is received in the notch (31) which prevents leakage of coolant under high pressure between the base body (12) and the coolant cap (14). [13] Coolant cap (14) for a rotating cutting tool (10), comprising: an outer surface (26); an inner surface (28) and a cylindrical outer surface (29) extending between the outer surface (26) and the inner surface (28), wherein the outer surface (26) of the coolant cap (14) contacts a retaining ring (20) when high-pressure coolant is introduced into a base body (12) to removably secure the coolant cap (14) to the base body (12), wherein the inner surface (28) of the coolant cap (14) has a flat lower inner surface (28a), an arcuate inner surface (28b) extending radially outward with respect to the lower inner surface (28a), and a flat upper inner surface (28c) extending radially outward from the arcuate inner surface (28b) to the cylindrical outer surface (29), wherein the cylindrical outer surface (29) has a first cylindrical outer surface portion (29a) with an outer diameter (D1) and a notch (31) formed therein, wherein a sealing element (34) is received in the notch (31) which prevents leakage of coolant under high pressure between the base body (12) and the coolant cap (14). [14] The coolant cap of claim 13, wherein the outer surface (26) of the coolant cap (14) includes a planar upper outer surface (26a), an arcuate outer surface (26b) extending radially outwardly with respect to the upper outer surface (26a), and a planar lower outer surface (26c) extending radially outwardly from the arcuate outer surface (26b) to the cylindrical outer surface (29). [15] Coolant cap according to claim 14, wherein the retaining ring (20) contacts the planar lower outer surface (26c) when high pressure coolant is introduced into the base body (12). [16] A coolant cap according to any one of claims 13 to 15, wherein the cylindrical outer surface (29) comprises a first cylindrical outer surface portion (29a) extending axially from the inner surface (28) and having a notch (31) formed therein, and a second cylindrical outer surface portion (29b) extending axially between the first cylindrical outer surface portion (29a) and the outer surface (26), wherein an outer diameter (D2) of the second cylindrical outer surface portion (29b) is larger than an outer diameter (D1) of the first cylindrical outer surface portion (29a).

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