Turning cutting tool

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) 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 the groove depth (d) occurs.

Description

TECHNICAL AREA

[0001] 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

[0002] 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.

[0003] 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 ON THE STATE OF TECHNICAL PATENT DOCUMENTS Patent document 1: Japanese unexamined published patent application JP 2014-058035 A Patent document 2: DE 40 19 428 A1 Patent document 3: US 5,085,540 A Patent document 4: US 2010 / 0 143 055 A1

[0004] DE 40 19 428 A1 discloses a shank tool with a cylindrical shank and cutting edges arranged at the head, wherein the shank is provided with at least one flattening that extends from the end face of the shank to the cutting edges.

[0005] US 5,085,540 A discloses 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 delivery increases machine efficiency by thoroughly lubricating the cutting tool.

[0006] US 2010 / 0143055 A1 discloses 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

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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 the shaft section by utilizing grooves provided in an outer circumferential surface of the shaft section as coolant channels. The present invention was developed on the basis of this discovered fact. MEASURES TO SOLVENT THE PROBLEM

[0011] The object of the present invention is achieved by a rotary cutting tool having the features of claim 1.

[0012] Beneficial further training is subject to dependent claims. EFFECTS OF INVENTION

[0013] In the rotary cutting tool of the present invention, the shank section has a plurality of coolant-carrying recessed grooves (recessed coolant guide grooves) provided in the outer circumferential surface of the shank section and spaced apart from one another in the circumferential direction such that the initial end of each of the recessed coolant guide grooves is located in the end face of the shank section, and such that the final end (end piece end) of each of the recessed coolant guide grooves is located in the chamfered outer circumferential surface of the connecting section, wherein each of the recessed coolant guide grooves has a flat groove cross-section such that the groove width is greater than the groove depth, and wherein each of the recessed- The coolant guide grooves are designed to direct the coolant from the shank section to the connecting section. Compared to a case where a coolant guide hole passes through the shank section, this design allows for a sufficient flow rate of coolant to suppress cutting edge wear and achieve favorable cutting efficiency, without significantly increasing the diameter or reducing the stiffness of the shank section.Furthermore, on a downstream side of the regional groove depth change position at each of the recessed coolant guide grooves, the coolant flowing in the respective recessed coolant guide groove forms a laminar flow with a flat cross-section, the thickness of which is limited in a radial direction of the turning cutting tool, so that the coolant flowing out of the respective recessed coolant guide groove through the end piece is moved along the chamfered outer circumferential surface of the connecting section to the wing section, thereby enabling the delivery of coolant to the cutting edge of the wing section at a sufficient rate and thus enabling the progression of cutting edge wear and efficient cutting.

[0014] Preferably, the wing section has a circumferential cutting edge section provided on an outer circumferential surface of the wing section and an end cutting edge section provided on an end surface of the wing section. Due to this design, the coolant flowing from each of the recessed coolant guide grooves through the end piece is conveyed along the inclined outer circumferential surface of the connecting section to the circumferential cutting edge section and the end cutting edge section of the wing section, so that the coolant can be supplied to the circumferential cutting edge section and the end cutting edge section at a sufficient rate to suppress the progression of cutting edge wear and achieve efficient cutting.

[0015] Furthermore, the groove width of each of the recessed coolant guide grooves is preferably constant, and the recessed coolant guide grooves are designed to occupy 50% or less of the outer circumferential surface of the shaft section. Since each of the recessed coolant guide grooves has a constant groove width, turbulence is unlikely to occur in the coolant flowing through the recessed coolant guide grooves. Therefore, the coolant flowing out of each of the recessed coolant guide grooves through the end piece is conveyed along the inclined outer circumferential surface of the joint section to the circumferential cutting edge section and the end cutting edge section of the blade section, so that the coolant can be delivered to the blade section at a sufficient rate to suppress the progression of cutting edge wear and ensure efficient cutting.

[0016] Furthermore, the multitude of recessed coolant guide grooves preferably consists of three, four, five, or six recessed coolant guide grooves. This design prevents a reduction in the centering accuracy of the turning tool and a reduction in the stiffness of the shank section. If the number of recessed coolant guide grooves is less than two, the centering accuracy of the turning tool would be reduced. If the number of recessed coolant guide grooves is at least seven, the resistance to coolant flow would increase, making it impossible to deliver the coolant at a sufficient rate.

[0017] Furthermore, each of the recessed coolant guide grooves preferably has a groove bottom shape in such a way that the groove depth is reduced (i.e., a distance from an axis of rotation increases) when the respective recessed coolant guide groove extends from the starting end to a regional groove depth change position where a trend change (course change, shift) of the groove depth occurs.This means that on a downstream side of the regional groove depth change position at each of the recessed coolant guide grooves, the coolant flowing in the respective recessed coolant guide groove forms a laminar flow with a flat cross-section, the thickness of which is limited in a radial direction of the turning cutting tool, so that the coolant flowing out of the respective recessed coolant guide groove through the end piece is moved along the chamfered outer circumferential surface of the connecting section to the wing section, thereby enabling the delivery of coolant to the cutting edge of the wing section at a sufficient rate and thus enabling the progression of cutting edge wear and efficient cutting.

[0018] Furthermore, the bottom of each of the recessed coolant guide grooves preferably has a so-called polyline shape (linear shape) or an arc shape with a predetermined radius of curvature at the regional groove depth change position. Due to this design, turbulence is unlikely to occur in the coolant flowing through the recessed coolant guide grooves when the coolant passes through the regional groove depth change position. Therefore, the coolant flowing out of each of the recessed coolant guide grooves through the end piece is directed along the chamfered outer circumferential surface of the connecting section to the blade section in such a way that the coolant is delivered to the cutting edge of the blade section at a sufficient rate to suppress the progression of cutting edge wear and ensure efficient cutting.

[0019] Furthermore, the distance from the axis of rotation of the turning tool to the groove bottom of each of the recessed coolant guide grooves is preferably constant or gradually decreasing as the respective recessed coolant guide groove extends from the regional groove depth change position to the end of the workpiece. Due to this design, turbulence in the coolant within the recessed coolant guide grooves is unlikely as the coolant flows from the regional groove depth change position to the end of the workpiece.Therefore, the coolant flowing out of each of the recessed coolant guide grooves through the end piece is moved along the chamfered outer circumferential surface of the connecting section to the wing section in such a way that the supply of coolant to the cutting edge of the wing section is enabled at a sufficient rate to suppress the progression of cutting edge wear and to make cutting efficient.

[0020] Furthermore, preferably, the bottom of each of the recessed coolant guide grooves, extending from the initial end to the regional groove depth change position, has a straight shape with a constant gradient, or an arc shape with a predetermined radius of curvature whose center lies on a plane containing an axis of rotation of the turning tool and having a lateral centerline that passes through the lateral center of each of the recessed coolant guide grooves. Due to this design, turbulence is unlikely to occur in the coolant flowing through the recessed coolant guide grooves from the initial end to the final end.Therefore, the coolant flowing out of each of the recessed coolant guide grooves through the end piece is moved along the chamfered outer circumferential surface of the connecting section to the wing section in such a way that the coolant can be supplied to the cutting edge of the wing section at a sufficient rate to prevent the progression of cutting edge wear and to achieve efficient cutting.

[0021] Furthermore, part of the shaft section is placed (fitted) into a tool holder hole of a tool holder, and the regional groove depth change position is positioned inside the tool holder hole.Due to this design, on the downstream side of the regional groove depth change position in each of the recessed coolant guide grooves, the coolant flowing in each of the recessed coolant guide grooves forms a laminar flow with a flat cross-section, the thickness of which is limited in the radial direction of the turning cutting tool, so that the coolant flowing out of the respective recessed coolant guide groove through the end piece is moved along the chamfered outer circumferential surface of the connecting section to the wing section, thereby enabling the delivery of the coolant to the cutting edge of the wing section at a sufficient rate and thus suppressing the progression of cutting edge wear and achieving efficient cutting. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 shows a perspective view of a rotary cutting tool according to an embodiment of the present invention. Fig. Figure 2 shows a cross-sectional view of the rotary cutting tool. Fig. 1. Fig. Figure 3 shows a view of an end face of the rotary cutting tool. Fig. 1. Viewing from one side of a shaft section of the turning tool. Fig. Figure 4 shows a view of an end face of the rotary cutting tool. Fig. 1 considering one side of a wing section of the rotary cutting tool. Fig. Figure 5 shows a view of a cross-section of the rotary cutting tool made of Fig. 1, wherein the cross-section is recorded near a regional groove depth change position in the shaft section. Fig. Figure 6 shows a view to illustrate a condition in which the turning cutting tool is made of Fig. 1 is attached to a tool holder. Fig. 7 shows a Fig. 2 corresponding view, showing a longitudinal section of a rotary cutting tool according to a further embodiment according to the present invention. Fig. 8 shows a Fig. 2 corresponding view, showing a longitudinal section of a rotary cutting tool according to yet another embodiment of the present invention. Fig. Figure 9 shows a magnified view of a section of the rotary cutting tool. Fig. 8, where the section is near the regional groove depth change position. Fig. 10 shows a Fig. 2 corresponding view, showing a longitudinal section of a rotary cutting tool according to yet another embodiment of the present invention. Fig. Figure 11 shows a view of a cross-section of a rotary cutting tool according to yet another embodiment of the present invention, wherein the cross-section is taken near the regional groove depth change position in the shank section. Fig. Figure 12 shows a view of a cross-section of a rotary cutting tool according to yet another embodiment of the present invention, wherein the cross-section is taken near the regional groove depth change position in the shank section. MODES FOR EXECUTING THE INVENTION

[0022] Some embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that, where necessary for the sake of clarity, the drawings in the embodiments described below have been simplified or made less precise, and that a particular section is not necessarily depicted exactly with regard to dimensions, shape, etc. EXAMPLE OF EXECUTION 1

[0023] Fig. Figure 1 shows a rotary cutting tool 10 according to an embodiment of the present invention. The rotary cutting tool 10 is manufactured by cutting a single material such as tool steel or cemented carbide and has a wing section (blade section) 12 with a cutting edge provided thereon, a cylindrically shaped shank section 14 with a diameter larger than the diameter of the wing section 12, and a connecting section 16 with a chamfered outer circumferential surface 16h, which connects the wing section 12 and the shank section 14 such that the wing section 12, the shank section 14, and the connecting section 16 are integrally formed.The wing section 12 has a circumferential cutting edge section 32, which is provided on an outer circumferential surface 12a of the wing section 12, and an end cutting edge section 34, which is provided on an end surface 12b of the wing section 12. That is, the wing section 12 is used, for example, in an end mill or a thread cutter. In the drawings, with the exception of . Fig. Figure 1 shows the wing section 12 represented by a cylindrically shaped rotational trajectory of the circumferential cutting edge section 32 and the end cutting edge section 34. This can be interpreted as the circumferential cutting edge section 32 and the end cutting edge section 34 cooperating to form the cutting edge described above, which is provided in the wing section 12; namely, the circumferential cutting edge section 32 and the end cutting edge section 34 are encompassed in the cutting edge provided in the wing section 12.

[0024] Fig. Figure 2 shows a cross-section containing a rotation axis C of the turning cutting tool 10. Fig. Figure 3 shows a left end face of the rotary cutting tool 10. Fig. 2, that is, an end surface of the rotary cutting tool 10, considering one side of the shank section 14. Fig. Figure 4 shows a right end face of the rotary cutting tool 10. Fig. 2, that is, an end surface of the rotary cutting tool 10, considering one side of the wing section 12. Fig. Figure 5 shows a view of a cross-section (transverse cross-section) near a regional groove depth change position P in the shaft section 14.

[0025] As this is shown in the Fig. As shown in Figures 2 to 5, the shaft section 14 has a plurality of recessed coolant guide grooves 18 (three recessed coolant guide grooves 18 in the present embodiment) provided on its outer circumferential surface 14a and spaced apart from one another at a constant distance in a circumferential direction of the shaft section 14, such that a starting end 18a of each of the recessed coolant guide grooves 18 is located at an end surface 14b of the shaft section 14 and that a terminal end 18b of each recessed coolant guide groove 18 is located in the chamfered outer circumferential surface 16a of the connecting section 16. Each of the recessed coolant guide grooves 18 has a shallow groove cross-section such that a groove width w of each of the recessed coolant guide grooves 18 is greater than a groove depth d of each of the recessed coolant guide grooves 18.The groove depth d is a measure of each recessed coolant guide groove 18, measured in a radial direction along the outer circumferential surface 14a of the shaft section a of the shaft section 14, the radial direction passing through the center, viewed in the width direction, of each of the recessed coolant guide grooves 18. The groove width w is a measure of each of the recessed coolant guide grooves 18, measured in a direction perpendicular to the radial direction described above and passing through the center, viewed in the width direction, of each of the recessed coolant guide grooves 18.

[0026] The groove width w of each of the plurality of recessed coolant guide grooves 18 is constant from the starting end 18a to the end piece end 18b. The plurality of recessed coolant guide grooves 18 cooperate in such a way that they occupy 50% or less of the outer circumferential area 14a of the shaft section 14. The number of the plurality of recessed coolant guide grooves 18 can be any number from three to six.

[0027] Each of the recessed coolant guide grooves 18 has a groove bottom shape such that the groove depth d decreases as the respective recessed coolant guide groove 18 extends from the initial end 18a to the regional groove depth change position P, where a trend change (course change, shift) of the groove depth (change tendency of the groove depth) of a groove bottom 18c occurs, namely such that a distance h from the axis of rotation C to the groove bottom 18c increases as the respective recessed coolant guide groove 18 extends from the initial end 18a to the regional groove depth change position P. The regional groove depth change position P is a position at which an inclination angle of the groove bottom 18c of each of the recessed coolant guide grooves 18 changes regionally, for example from a positive value (positive gradient) to zero (flat with zero gradient) or from a positive value to a negative value (negative gradient).This means that the regional groove depth change position P is the position at which the groove bottom 18c has a so-called polyline shape.

[0028] Furthermore, each recessed coolant guide groove 18 has a groove bottom shape such that the distance h from the axis of rotation C to the groove bottom 18c is constant when the respective recessed coolant guide groove 18 extends from the regional groove depth change position P to the end piece end 18b. The groove bottom 18c of each recessed coolant guide groove 18 has an inclined surface extending from the initial end 18a to the regional groove depth change position P, and a flat surface extending from the regional groove depth change position P to the end piece end 18b, wherein the inclined surface is inclined with respect to the axis of rotation C by an angle of inclination α, for example, and the flat surface is inclined with respect to the axis of rotation C by an angle of inclination of zero, for example.

[0029] Fig. Figure 6 shows a view of a state in which the shank section 14 of the turning cutting tool 10 is seated in a tool holder hole 22 of a tool holder 20 when a cutting operation is to be performed. The tool holder 20 is mounted on a spindle of a machine tool (not shown), and coolant is supplied to the tool holder hole 22 of the tool holder 20 through a coolant channel 24 that passes axially through the spindle and the tool holder 20. In the state in which the shank section 14 is seated in the tool holder hole 22, a portion of the shank section 14, located on one side of the connecting section 16, is exposed such that the regional flute depth change position P is positioned inside the tool holder hole 22.In the state where the shaft section 14 is seated in the tool holder hole 22 of the tool holder 20, the coolant is supplied into the tool holder hole 22 of the tool holder 20 through the coolant channel 24, and is then supplied to the cutting edge of the wing section 12 through the recessed coolant guide grooves 18 provided in the shaft section 14.

[0030] The coolant, which is caused to flow into each recessed coolant guide groove 18 through the initial end 18a, is caused to flow in the respective recessed coolant guide groove 18 with a constant width. A flow rate of the coolant is increased due to a reduction in the flow cross-sectional area of ​​each of the recessed coolant guide grooves 18 until the coolant reaches the regional groove depth change position P, and is thereafter essentially constant after the coolant has passed through the regional groove depth change position P and when the coolant flows out of each recessed coolant guide groove 18 through the end piece end 18b.The coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is drawn towards the axis of rotation C due to its viscosity and surface tension. This causes the coolant to move against a centrifugal force along the chamfered outer circumferential surface 16a of the connecting section 16, reaching the blade section 12. This delivers the coolant to the circumferential cutting edge section 32 and the end cutting edge section 34 of the blade section 12. Furthermore, on a downstream side of the regional groove depth change position P in each recessed coolant guide groove 18, the coolant forms a laminar flow with a flat cross-section whose thickness is limited in a radial direction of the blade section 12.The coolant flows out of each recessed coolant guide groove 18 through the end piece end 18b, while a laminar flow is formed such that the coolant is moved along the chamfered outer circumferential surface 16a and reaches the wing section 12 in such a way that it is supplied to the circumferential cutting edge section 32 and to the end cutting edge section 34 of the wing section 12. In the . Fig. 2 and Fig. Figure 6 shows a schematic representation of the coolant flow by means of a dashed line, represented by an arrow Fw.

[0031] As described above, in the rotary cutting tool 10 of the present embodiment, the shank section 14 has three recessed coolant guide grooves 18, which are provided in the outer circumferential surface 14a of the shank section 14 and which are spaced apart from each other in the circumferential direction, such that the initial end 18a of each recessed coolant guide groove 18 is located in the end surface 14b of the shank section 14 and that the end piece end 18b of each recessed coolant guide groove 18 is located in the chamfered outer circumferential surface 16a of the connecting section 16, wherein each recessed coolant guide groove 18 has the flat groove cross-section such that the groove width w is greater than the groove depth d, and wherein each recessed coolant guide groove 18 is designed in such a way that it guides the coolant from the shank section 14 to the connecting section 16.In contrast to a case where the coolant guide hole is designed to pass through the shaft section 14, the coolant can be supplied at a sufficient (satisfactory) rate such that the progression of cutting edge wear of the wing section 12 is avoided and efficient cutting is achieved without significantly increasing the diameter of the shaft section 14 and without significantly reducing the stiffness of the shaft section 14.

[0032] In the rotary cutting tool 10 of the present embodiment, the wing section 12 serves as a known end mill or thread cutter and has a peripheral cutting edge section 32, which is provided in the outer circumferential surface of the wing section 12, and the end cutting edge section 34, which is provided in the end face of the wing section 12. Due to this design, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is moved along the chamfered outer circumferential surface 16a of the connecting section 16 to the peripheral cutting edge section 32 and to the end cutting edge section 34 of the wing section 12 in such a way that the coolant can be supplied to the peripheral cutting edge section 32 and the end cutting edge section 34 at a sufficient rate to prevent premature cutting edge wear and to achieve efficient cutting.

[0033] In the turning tool 10 of the present embodiment, the groove width w of each recessed coolant guide groove 18 is constant, and the recessed coolant guide grooves 18 are designed to occupy 50% or less of the outer circumferential area 14a of the shank section 14. Since each of the recessed coolant guide grooves 18 has the constant groove width w, turbulence is unlikely to occur in the coolant guided through the recessed coolant guide grooves 18.Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is conveyed along the chamfered outer circumferential surface 16a of the connecting section 16 to the circumferential cutting edge section 32 and the end cutting edge section 34 of the wing section 12, so that the coolant can be supplied to the wing section 12 at a sufficient rate to prevent premature cutting edge wear and achieve efficient cutting. Furthermore, since the recessed coolant guide grooves 18 are designed to occupy 50% or less of the outer circumferential surface 14a of the shaft section 14, the stiffness of the shaft section 14 is not reduced to such an extent that its practical applicability is diminished.

[0034] In the turning tool 10 of the present embodiment, the recessed coolant guide grooves 18, which are provided in plurality, consist of three, four, five, or six recessed coolant guide grooves 18. This design makes it possible to avoid a reduction in the centering accuracy of the turning tool 10 and a reduction in the stiffness of the shank section 14. If the number of recessed coolant guide grooves 18 is no greater than two, the centering accuracy of the turning tool 10 would be reduced. If the number of recessed coolant guide grooves 18 is no less than seven, the resistance to the coolant flow would be increased, making it impossible to supply the coolant at a sufficient rate.

[0035] In the rotary cutting tool 10 of the present embodiment, each of the recessed coolant guide grooves 18 has a groove bottom shape such that the groove depth d is reduced, that is, the distance h from the axis of rotation C increases along the extension of each recessed coolant guide groove 18 from the initial end 18a to the regional groove depth change position P, where the change tendency of the groove depth d occurs (where the groove depth changes). That is, on the downstream side of the regional groove depth change position P in each recessed coolant guide groove 18, the coolant flowing in each recessed coolant guide groove 18 forms a laminar flow with a flat cross-section whose thickness is limited in the radial direction of the vane section 12, so that the coolant flowing from each recessed coolant guide groove 18 The coolant flowing out through the end piece 18b is moved along the chamfered outer circumferential surface 16a of the connecting section 16 to the wing section 12, whereby the coolant can be supplied to the cutting edge of the wing section 12 at a sufficient rate and accordingly the progression of cutting edge wear is suppressed and efficient cutting is achieved.

[0036] In the rotary cutting tool 10 of the present embodiment, a surface of the groove bottom 18c of each recessed coolant guide groove 18 has a so-called polyline shape at the regional groove depth change position P. Due to this design, turbulence is unlikely to occur in the coolant flowing in the recessed coolant guide grooves 18 when the coolant passes through the regional groove depth change position P. Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is moved along the chamfered outer circumferential surface 16a of the connecting section 16 to the blade section 12 in such a way that the coolant can be supplied to the cutting edge of the blade section 12 at a sufficient rate to suppress the progression of cutting edge wear and achieve efficient cutting.

[0037] In the rotary cutting tool 10 of the present embodiment, the distance h from the axis of rotation C of the rotary cutting tool C is to The coolant flow rate at the bottom of the groove 18c of each recessed coolant guide groove 18 is constant as the respective recessed coolant guide groove 18 extends from the regional groove depth change position P to the end piece end 18b. Due to this design, turbulence in the coolant within the recessed coolant guide grooves 18 is unlikely as the coolant flows from the regional groove depth change position P to the end piece end 18b. Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is directed along the chamfered outer circumferential surface 16a of the connecting section 16 to the blade section 12 in such a way that sufficient coolant can be delivered to the cutting edge of the blade section 12 to suppress cutting edge wear and achieve efficient cutting.

[0038] In the rotary cutting tool 10 of the present embodiment, the groove bottom 18c of each recessed coolant guide groove 18 has a straight shape with a constant gradient in at least the section extending from the initial end 18a to the regional groove depth change position P. Due to this design, turbulence is unlikely to occur in the coolant flowing through the recessed coolant guide grooves 18 from the initial end 18a to the end piece end 18b. Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is guided along the chamfered outer circumferential surface 16a of the connecting section 16 to the blade section 12 in such a way that the coolant can be supplied to the cutting edge of the blade section 12 at a sufficient rate to prevent premature cutting edge wear and achieve efficient cutting.

[0039] In the turning cutting tool 10 of the present embodiment, a section of the shank section 14 serves to insert it into the tool holder hole 22 of the tool holder 20, and the regional groove depth change position P serves to position it inside the tool holder hole 22.Due to this design, on the downstream side of the regional groove depth change position P in each recessed coolant guide groove 18, the coolant flowing in the respective recessed coolant guide groove 18 forms a laminar flow with a flat cross-section, the thickness of which is limited in the radial direction of the rotary cutting tool 10, such that the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is moved along the chamfered outer circumferential surface 16a of the connecting section 16 to the wing section 12, thereby enabling the supply of coolant to the cutting edge of the wing section 12 at a sufficient rate and accordingly suppressing the progression of cutting edge wear and achieving efficient cutting. EXAMPLE OF EXECUTION 2

[0040] Further embodiments of the present invention are described below. The same reference numerals as in the embodiment described above have been used in the following embodiments to indicate the practically corresponding elements, and their description is not repeated.

[0041] Fig. 7 shows a Fig. Figure 2 shows a corresponding view and a cross-section of a rotary cutting tool 50 according to another embodiment of the present invention. As shown in Figure 2, the following is a cross-section of a rotary cutting tool 50 according to another embodiment of the present invention. Fig. As shown in Figure 7, the turning cutting tool 50 is essentially the same as the turning cutting tool 10, except that the turning cutting tool 10 differs in that the groove bottom 18c of each recessed coolant guide groove 18 has an arc shape rather than a polyline shape at the regional groove depth change position, where the arc shape has a predetermined radius of curvature R1.

[0042] In the rotary cutting tool 50 of this embodiment, the groove bottom 18c of each recessed coolant guide groove 18 at the regional groove depth change position P has an arc shape with a predetermined radius of curvature R1. Due to this design, turbulence is unlikely to occur in the coolant flowing in the recessed coolant guide grooves 18 when the coolant passes through the regional groove depth change position P. Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is directed along the chamfered outer circumferential surface 16a of the connecting section 16 to the blade section 12 such that the coolant can be delivered to the cutting edge of the blade section 12 at a sufficient rate to suppress the progression of cutting edge wear and achieve efficient cutting. EXAMPLE OF EXECUTION 3

[0043] Fig. 8 shows a Fig. Figure 2 shows a corresponding view and a cross-section of a rotary cutting tool 60 according to a further embodiment of the present invention. As shown in Figure 2, the following is a cross-section of a rotary cutting tool 60 according to a further embodiment of the present invention. Fig. As shown in Figure 8, the turning tool 60 is essentially the same as the turning tool 10, differing from the turning tool 10 in that the groove bottom 18c of each recessed coolant guide groove 18 has an arc shape rather than a polyline shape at the regional groove depth change position P, where the arc shape has a predetermined radius of curvature R1, and in that each recessed coolant guide groove 18 has a groove bottom shape such that the distance h from the axis of rotation C gradually decreases from the regional groove depth change position P to the end piece end 18b (that is, the groove bottom 18c of each recessed coolant guide groove 18 has an inclined surface extending from the regional groove depth change position P to the end piece end 18b, the inclined surface having a gradient with a negative angle of inclination β).

[0044] Fig. Figure 9 shows a magnified view of a section of the rotary cutting tool 60. Fig. 8, wherein this section is near the regional groove depth change position P. The groove bottom 18c of each recessed coolant guide groove 18 regionally defines an arc with a predetermined radius of curvature R1 at the regional groove depth change position P, which is provided in the shaft section 14, and at which the groove depth of each recessed coolant guide groove 18 changes regionally.

[0045] In the rotary cutting tool 60 of the present embodiment, the groove bottom 18c of each recessed coolant guide groove 18 has an inclined surface extending from the initial end 18a to the regional groove depth change position P, and another inclined surface extending from the regional groove depth change position P to the end piece end 18b, wherein the inclined surface is inclined with respect to the axis of rotation C by, for example, the angle of inclination α, and the other inclined surface is inclined with respect to the axis of rotation C by, for example, the negative angle of inclination β.

[0046] In the rotary cutting tool 60 of the present embodiment, the distance h of the groove bottom 18c from the axis of rotation C of the rotary cutting tool 60 gradually decreases along the length of each recessed coolant guide groove 18 from the regional groove depth change position P to the end piece end 18b. Due to this design, it is unlikely that turbulence will occur in the coolant in the recessed coolant guide grooves 18 when the coolant flows from the regional groove depth change position P to the end piece end 18b.Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b is moved along the chamfered outer circumferential surface 16a of the connecting section 16 to the wing section 12 in such a way that the coolant can be supplied to the cutting edge of the wing section 12 at a sufficient rate to prevent the progression of cutting edge wear and to achieve efficient cutting. EXAMPLE OF EXECUTION 4

[0047] Fig. 10 shows a Fig. 2 corresponding view and shows a cross-section of a rotary cutting tool 70 of a further embodiment of the present invention. Fig. Figure 10 shows a plane containing the axis of rotation C of the turning tool 70 and a width-direction centerline that passes through the center, viewed in the width direction, of a recessed coolant guide groove 18. The turning tool 70 differs from the turning tool 10 in that the groove bottom 18c of each recessed coolant guide groove 18 has an arc shape having a predetermined radius of curvature R2, the center of which lies on the plane described above, wherein the predetermined radius of curvature R2 is sufficiently larger than the predetermined radius of curvature R1 such that the distance H of the groove bottom 18c gradually increases along the extension of each of the recessed coolant guide grooves 18 from the initial end 18a to the regional groove depth change position P.

[0048] In the turning tool 70 of the present embodiment, the groove bottom 18c of each recessed coolant guide groove 18 has, at least in its section extending from the initial end 18a to the regional groove depth change position P, an arc shape with a predetermined radius of curvature R2, the center of which lies on the plane containing the axis of rotation C of the turning tool 70, and the width-direction centerline passing through the center, viewed in the width direction, of each recessed coolant guide groove 18. Due to this design, turbulence is unlikely to occur in the coolant flowing in the recessed coolant guide grooves 18 from the initial end 18a to the end piece end 18b.Therefore, the coolant flowing out of each recessed coolant guide groove 18 through the end piece end 18b moves along the chamfered outer circumferential surface 16a of the connecting section 16 to the wing section 12 in such a way that the coolant can be supplied to the cutting edge of the wing section 12 at a sufficient rate to suppress the progression of cutting edge wear and achieve efficient cutting. EXAMPLE OF EXECUTION 5

[0049] Fig. 11 shows a Fig. Figure 3 shows a corresponding view and a cross-section of the recessed coolant guide grooves 108 provided in the shaft section 14, in a further embodiment of the present invention, wherein the cross-section is perpendicular to the axis of rotation C. The in Fig. The recessed coolant guide grooves 108 shown in Figure 11 differ from those in Figure 108. Fig. In the 3 shown recessed coolant guide grooves 18, in which the groove bottom 18c of each groove has a straight shape in one direction of the groove width b, the groove bottom 108c of each recessed coolant guide groove 108 is curved such that it has an arc shape whose center of curvature corresponds to the axis of rotation C such that the groove depth d is constant in one direction of the groove width b (namely in the circumferential direction). In the present embodiment, a flattening f [= (w - d) / w] of the cross-section of each of the recessed coolant guide grooves 108 has a size of 0.81. It should be noted here that a flattening f of the cross-section of each of the recessed coolant guide grooves 18, which in Fig. The 3 shown have a size of 0.75. EXAMPLE OF EXECUTION 6

[0050] Fig. 12 shows a Fig. Figure 3 shows a corresponding view and a cross-section of the recessed coolant guide grooves 118 provided in the shaft section 14, in a further embodiment of the present invention. The recessed coolant guide grooves 118 are made of Fig. 12 differ from the recessed coolant guide grooves 18. Fig. 3, in which each has the groove bottom 18c in a straight shape in the direction of the groove width d, such that a groove bottom 118c of each of the recessed coolant guide grooves 118 is curved such that it has an arc shape, the center of curvature of which is located on the side opposite the axis of rotation C, such that the groove depth d increases from each of its opposite ends to its center in the direction of the groove width w (i.e., in the circumferential direction). In the present embodiment, the flattening f [= (w - d) / w] of the cross-section of each of the recessed coolant guide grooves 118 is 0.78.

[0051] While exemplary embodiments of the present invention have been described in detail above with reference to the drawings, it should be understood that the invention can also be implemented in other ways.

[0052] For example, each recessed coolant guide groove 18 is provided with the regional groove depth change position P, where the groove depth changes regionally (becomes different locally). However, the regional groove depth change position P does not necessarily have to be provided in every one of the recessed coolant guide grooves 18. For example, the distance of the groove bottom 18c of each of the recessed coolant guide grooves 18 from the axis of rotation C from the start end 18a to the end piece end 18b can be constant.

[0053] Furthermore, each of the turning cutting tools 10, 50, 60, 70 of the embodiments described above is provided with the three recessed coolant guide grooves 18. However, the number of recessed coolant guide grooves 18 can be any number of three, four, five, and six.

[0054] Furthermore, in the turning cutting tool 60 of the embodiment described above, the groove bottom 18c of each recessed coolant guide groove 18 has an inclined surface extending from the starting end 18a to the regional groove depth change position P, wherein this inclined surface is inclined, for example, by the angle of inclination α with respect to the axis of rotation C. However, the angle of inclination α can also be zero.

[0055] Furthermore, in each of the rotary cutting tools 10, 50, 60, 70 of the embodiments described above, the diameter of the wing section 12 is not greater than 10 mm, preferably not greater than 8 mm, with a diameter of 0.05 mm to 4.0 mm being even more preferred, and with a diameter of 0.05 mm to 3.0 mm being most preferred.

[0056] While the embodiments of the present invention are described with reference to the accompanying drawings, it should be understood that the invention is also applicable to other forms within the scope of the invention. REFERENCE MARK LIST 10, 50, 60, 70 Turning cutting tool 12 Wing section 12a External perimeter area 12b End surface 14 shaft section 14a External perimeter area 14b End surface 16 Connecting section 16a chamfered outer circumferential surface 18, 108, 118 recessed coolant guide groove 18a Start End 18b End piece 18c, 108c, 118c Grooved floor 20 tool holders 22 Tool holder holes 32 Circumferential cutting edge section 34 End cutting edge section P regional groove depth change position C axis of rotation d groove depth b Groove width h distance

Claims

Rotary cutting tool (10; 50; 60; 70) comprising: a wing section (12) with a cutting edge (32, 34) provided in the wing section (12); a shank section (14) with a diameter greater than the diameter of the wing section (12); and a chamfered connecting section (16) connecting 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) provided in an outer circumferential surface (14a) of the shaft section (14) and spaced apart circumferentially 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 piece 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 the groove depth (d) occurs.; Rotary 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). 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 shank section (14). Rotary 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). 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). Rotary cutting tool (10; 50; 60; 70) according to claim 1 or 5, wherein a distance (h) from an axis of rotation (C) of the rotary cutting tool to the groove bottom (18c; 108c; 118c) of each recessed coolant guide groove (18; 108; 118) is constant or gradually decreases extending each recessed coolant guide groove (18; 108; 118) from the regional groove depth change position (P) to the end piece end (18b). A rotary cutting tool (10; 50; 60; 70) according to any one of 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) the center of which lies on a plane containing an axis of rotation (C) of the rotary cutting 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). Turning cutting tool (10; 50; 60; 70) according to one of claims 1 - 7, wherein a section of the shank 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).

Images