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DE-112019007348-B4 - Turning cutting tool

DE112019007348B4DE 112019007348 B4DE112019007348 B4DE 112019007348B4DE-112019007348-B4

Abstract

Rotary cutting tool (10; 50; 60; 70) with: a wing section (12) with a cutting edge (32, 34) provided in the wing section (12); a shaft section (14) with a diameter larger than the diameter of the wing section (12); and a beveled connecting section (16) that connects the wing section (12) and the shaft section (14); wherein the shaft section (14) has a plurality of recessed coolant guide grooves (18; 108; 118) which are provided in an outer circumferential surface (14a) of the shaft section (14) and which are spaced apart from each other in the circumferential direction such that an initial end (18a) of each of the recessed coolant guide grooves (18; 108; 118) is located in an end surface (14b) of the shaft section (14), and an end end (18b) of each of the recessed coolant guide grooves (18; 108; 118) is located in a chamfered outer circumferential surface (16a) of the connecting section (16); wherein each of the recessed coolant guide grooves (18; 108; 118) has a flat groove cross-section such that a groove width (w) of each recessed coolant guide groove (18; 108; 118) is greater than a groove depth (d) of each recessed coolant guide groove (18; 108; 118), wherein each recessed coolant guide groove (18; 108; 118) is designed to guide a coolant from the shaft section (14) to the connecting section (16), and wherein each of the recessed coolant guide grooves (18; 108; 118) has a groove bottom (18c; 108c; 118c) which is shaped such that the groove depth (d) decreases along the extent of each recessed coolant guide groove (18; 108; 118) from the start end (18a) to a regional groove depth change position (P) where a trend change in groove depth (d) occurs.

Inventors

  • Jiro Osawa
  • Tomonori YODA
  • Yusuke Tanaka

Assignees

  • OSG CORPORATION

Dates

Publication Date
20260513
Application Date
20190522

Claims (8)

  1. Rotary cutting tool (10; 50; 60; 70) with: a wing section (12) with a cutting edge (32, 34), which is provided in the wing section (12); a shaft section (14) having a diameter greater than the diameter of the wing section (12); and a chamfered connecting section (16) that connects the wing section (12) and the shaft section (14); wherein the shaft section (14) has a plurality of recessed coolant guide grooves (18; 108; 118) which are provided in an outer circumferential surface (14a) of the shaft section (14) and which are spaced apart from each other in the circumferential direction such that an initial end (18a) of each of the recessed coolant guide grooves (18; 108; 118) is located in an end surface (14b) of the shaft section (14), and an end end (18b) of each of the recessed coolant guide grooves (18; 108; 118) is located in a chamfered outer circumferential surface (16a) of the connecting section (16); wherein each of the recessed coolant guide grooves (18; 108; 118) has a shallow groove cross-section such that a groove width (w) of each recessed coolant guide groove (18; 108; 118) is greater than a groove depth (d) of each recessed coolant guide groove (18; 108; 118), wherein each recessed coolant guide groove (18; 108; 118) is designed to guide a coolant from the shaft section (14) to the connecting section (16), and wherein each of the recessed coolant guide grooves (18; 108; 118) has a groove bottom (18c; 108c; 118c) shaped such that the groove depth (d) decreases along the extension of each recessed coolant guide groove (18; 108; 118) from the initial end (18a) to a regional Groove depth change position (P) where a trend change in groove depth (d) occurs.
  2. Turning cutting tool (10; 50; 60; 70) according to Claim 1 , wherein the cutting edge (32, 34) provided in the wing section (12) has a circumferential cutting edge section (32) which is provided in an outer circumferential surface (12a) of the wing section (12) and an end cutting edge section (34) which is provided in an end surface (12b) of the wing section (12).
  3. Turning cutting tool (10; 50; 60; 70) according to Claim 1 or 2 , wherein the groove width (w) of each recessed coolant groove is constant, and the recessed coolant guide grooves (18; 108; 118) are provided such that they occupy 50% or less of the outer circumferential area (14a) of the shaft section (14).
  4. Turning cutting tool (10; 50; 60; 70) according to Claim 3 , wherein the plurality of recessed coolant guide grooves (18; 108; 118) consists of 3, 4, 5 or 6 recessed coolant guide grooves (18; 108; 118).
  5. Turning cutting tool (10; 50; 60; 70) according to Claim 1 , wherein the groove bottom (18c; 108c; 118c) of each recessed coolant guide groove (18; 108; 118) has a polyline shape or an arc shape having a predetermined radius of curvature (R1) at the regional groove depth change position (P).
  6. Turning cutting tool (10; 50; 60; 70) according to Claim 1 or 5 , wherein a distance (h) from a rotation axis (C) of the turning cutting tool to the groove bottom (18c; 108c; 118c) of each recessed coolant guide groove (18; 108; 118) is constant or gradually decreases along the extension of each recessed coolant guide groove (18; 108; 118) from the regional groove depth change position (P) to the end piece end (18b).
  7. Turning cutting tool (10; 50; 60; 70) according to one of the Claims 1 - 6 , wherein the groove bottom (18c; 108c; 118c) of each recessed coolant guide groove (18; 108; 118) has a straight shape with a constant gradient or an arc shape having a predetermined radius of curvature (R2) whose center lies on a plane containing an axis of rotation (C) of the turning tool (10; 50; 60; 70) and a width-direction centerline passing through a width-direction center of each of the recessed coolant guide grooves (18; 108; 118).
  8. Turning cutting tool (10; 50; 60; 70) according to one of the Claims 1 - 7 , wherein a section of the shaft section (14) is placed in a tool holding hole (22) of a tool holder (20), and the regional groove depth change position (P) is positioned inside the tool holding hole (22).

Description

TECHNICAL AREA The present invention relates to a rotary cutting tool with guide grooves for guiding a coolant, and in particular to a technique for efficiently cooling a cutting edge in such a way that the progression of cutting edge wear is suppressed without reducing the stiffness of the rotary cutting tool. BACKGROUND TO THE STATE OF THE TECHNOLOGY A turning tool, which is provided with a wing section having a relatively small diameter of, for example, 10 mm or less, has a shank section with a diameter larger than the diameter of the wing section. Since such a turning tool is driven and rotated at a relatively high speed, the wear of the cutting edge of the wing section is high. To suppress the progression of cutting edge wear, a coolant is supplied to the cutting edge of the wing section through the shank section in such a way that the cutting edge is cooled. A milling tool disclosed in patent document 1 is an example of such a turning tool. In the disclosed milling tool, a coolant guide hole is provided such that it extends through the shank section in one direction of its axis of rotation, and the coolant is supplied to the wing section from an outlet of the coolant guide hole, the outlet being provided with a chamfered connecting section that joins the shank section and the wing section. By supplying the coolant to the wing section, the cutting edge of the wing section is cooled, and chips generated during a cutting operation are discharged. DOCUMENTS OF THE STATE OF THE TECHNOLOGY PATENT DOCUMENTS Patent document 1: Japanese unexamined published patent application JP 2014-058035 APatent document 2: DE 40 19 428 A1Patent document 3: US 5 085 540 APatent document 4: US 2010 / 0 143 055 A1 DE 40 19 428 A1 discloses a shaft tool with a cylindrical shaft and cutting edges arranged at the head, wherein the shaft is provided with at least one flattening extending from the end face of the shaft to the cutting edges. US 5 085 540 A Figure 1 reveals a cutting tool. The shank of the cutting tool has a longitudinal groove on its outer surface. The groove extends from the outer end of the shank to the relief zone of the grooves. The shank is inserted into a coolant supply adapter. The coolant is directed from the adapter through the grooves to the grooves. This results in the delivery of high-pressure lubrication to the working area. The efficient lubricant supply increases machine efficiency by thoroughly lubricating the cutting tool. US 2010 / 0 143 055 A1 Disclosing a rotatably driven cutting tool, in particular a finishing tool such as a reamer, with integrated coolant/lubricant supply, for machining bores, in particular through bores, with a cutting part on which a plurality of cutting edges and flutes are formed, and a shank which forms a clamping section on a side facing away from the cutting part, wherein in the clamping section a number of coolant/lubricant channels corresponding to the number of flutes are formed such that the coolant/lubricant exiting from end face outlet openings of the clamping section can be fed in a free jet along the shank into each associated flute of the cutting part. REVELATION OF THE INVENTION TASK TO BE SOLVED BY THE INVENTION Furthermore, there is a case where the turning tool needs to rotate at a higher speed, requiring a higher coolant flow rate to increase cutting efficiency. However, with the conventional turning tool described above, increasing the cross-sectional area of the coolant guide hole passing through the shank section would reduce the shank section's stiffness. Therefore, since the cross-sectional area of the coolant guide hole is limited, the coolant flow is restricted due to flow resistance within the coolant guide hole. This results in situations where it is difficult to deliver the coolant to the cutting edge at a sufficient rate. This problem is exacerbated if the diameter of the cutting tool's vane section is small. On the other hand, if the diameter of the shaft section is increased, the coolant discharged from the outlet of the coolant guide hole, which passes through the shaft section, would be applied to a position that is spaced away from the cutting edge, and the circumferential speed of the wing section would be reduced, resulting in adverse effects such as accelerated cutting edge wear and a reduction in cutting efficiency. The present invention was made with regard to the background set out above. It is therefore an object of the present invention to provide a rotary cutting tool in which a coolant can be supplied to a cutting edge at a sufficient rate to suppress the progression of cutting edge wear and to achieve favorable cutting efficiency. Various experiments and investigations carried out by the inventors of the present invention and their associates under the aforementioned conditions have revealed that coolant can be supplied at a sufficient rate from the shaft section to the wing section without significantly reducing the stiffness of