Cutting Tools

Abstract

The present invention provides a cutting tool. The cutting tool (10) rotates around an axis (A0), and the cutting tool has a cutting edge portion (12). The cutting edge portion has a rake face (14) and a cutting edge (22). The rake face (14) is configured such that when the rake face (14) faces an imaginary plane (F) containing the axis and is parallel to the imaginary plane (F), the rake face (14) is located at a position deviating from the imaginary plane (F) in a direction opposite to the rotation direction (C) of the cutting tool (10). Thus, chip refinement can be achieved.

Description

Technical Field

[0001] The present invention relates to a cutting tool for cutting a workpiece by rotating. Background Art

[0002] A workpiece is cut using a cutting tool to produce various parts. Here, chips (debris) generated by cutting the workpiece may remain in the workpiece (the final part). The chips remaining in the part may hinder the movement of the part. Therefore, usually, the cut workpiece is cleaned with a solvent to remove the chips from the workpiece. However, depending on the shape of the chips, the chips may get stuck inside the workpiece. In this case, even if the workpiece is cleaned, the chips are not easily removed from the workpiece.

[0003] Therefore, a cutting tool has been developed that limits (controls) the shape of the chips and makes it easy to remove the chips. For example, Japanese Patent Publication No. 08-126904 discloses a technology for a cutting tool having a plurality of tiny longitudinal grooves, protrusions, or both. The cutting tool bends the chips into a clockwork shape through the grooves, etc. However, it is difficult to limit the length of the chips using this technology. If the chips become longer, it is difficult to remove the chips from the workpiece. Summary of the invention

[0004] Thus, it is a technical problem to make the chips finer in the cutting tool.

[0005] A cutting tool according to one embodiment of the present invention is a cutting tool that rotates about an axis, and has a cutting edge portion having a front cutting face and a cutting edge, wherein the front cutting face is configured such that when the front cutting face faces an imaginary plane containing the axis and is parallel to the imaginary plane, the front cutting face is located at a position deviating from the imaginary plane in a direction opposite to the rotation direction of the cutting tool.

[0006] According to the present invention, it is possible to provide a cutting tool capable of miniaturizing chips.

[0007] The above-mentioned objects, features and advantages will be easily understood from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a figure which shows the cutting tool which concerns on embodiment.

[0009] Figure 2 This is a diagram of the tip portion of the cutting tool as viewed along the axial direction.

[0010] Figure 3 This is a diagram of the tip portion of the cutting tool as viewed along the axial direction. DETAILED DESCRIPTION

[0011] Next, a cutting tool 10 according to an embodiment of the present invention will be described.

[0012] Figure 1 The cutting tool 10 shown is, for example, a reamer. The cutting tool 10 has a plurality of (here, 4) shaft portions S (Sa to Sd) and a plurality of (here, 4 types, and 4 of each type) cutting edge portions 12 (12a to 12d). The cutting tool 10 cuts the workpiece W while rotating around the axis A0. The cutting tool 10 can expand the drilled hole in 4 stages by the 4 types of cutting edge portions 12a to 12d.

[0013] The tip direction D and the base direction B of the cutting tool 10 are respectively Figure 1 Indicated by up and down arrows. The direction along the axis A0 is set to the axial direction A. The radial direction R of the cutting tool 10 is a direction orthogonal to the axis A0. The radial outer side O of the cutting tool 10 is the radial direction R from the axis A0 toward the outer periphery of the cutting tool 10. In addition, the radial inner side I of the cutting tool 10 is the radial direction R from the outer periphery of the cutting tool 10 toward the axis A0.

[0014] The four shaft portions S (shaft portions Sa to Sd) are connected in sequence along the axis A0. On each of the four shaft portions S, four cutting edge portions 12 (12a to 12d) are installed at intervals on a circle centered on the axis A0. That is, four cutting edge portions 12a are installed on the shaft portion Sa. Similarly, four cutting edge portions 12b are installed on the shaft portion Sb. In addition, four cutting edge portions 12c are installed on the shaft portion Sc. And, four cutting edge portions 12d are installed on the shaft portion Sd.

[0015] The four cutting edge portions 12a respectively have a rake face 14a, a top face 16a, an outer peripheral end face 18a, an oblique end face 20a, a cutting edge 22a and a plurality of grooves 24a. Each cutting edge portion 12a generates chips by cutting the workpiece W. The rake face 14a is a surface through which the chips pass. After the chips generated by the cutting edge portion 12a pass on the rake face 14a, they are discharged to the outside of the cutting tool 10. The top face 16a is an end face located in the top direction D of the rake face 14a. The outer peripheral end face 18a is an end face located radially outside O of the rake face 14a. The oblique end face 20a is an end face formed between the top face 16a and the outer peripheral end face 18a.

[0016] The cutting edge 22a is formed at the boundary between the rake face 14a and the oblique end face 20a. The plurality of grooves 24a are arranged side by side on the rake face 14a. The plurality of grooves 24a each have an end reaching the cutting edge 22a. The plurality of grooves 24a are used to supply lubricating fluid to the cutting edge 22a. The plurality of grooves 24a are inclined toward the radial outer side O relative to the axial direction A as they approach the tip direction D. As a result, the plurality of grooves 24a can more effectively supply lubricating fluid to the cutting edge 22a by the centrifugal force generated by the rotation of the cutting tool 10.

[0017] In the present embodiment, the frictional resistance between the chip and the front cutting face 14a can be reduced as follows. First, by providing a plurality of grooves 24a on the front cutting face 14a, the contact area between the chip and the front cutting face 14a can be reduced. Accordingly, the frictional resistance is reduced. In addition, the lubricating fluid reaches the cutting edge 22a via the plurality of grooves 24a. Accordingly, after the chip is formed by the cutting edge 22a, the lubricating fluid can immediately reduce the frictional resistance between the chip and the front cutting face 14a.

[0018] In this way, when the frictional resistance between the chip and the front cutting edge 14a is reduced, the chip curls as described below and is then cut off. First, by reducing the frictional resistance between the chip and the front cutting edge 14a, the chip is easily removed from the front cutting edge 14a. Therefore, the newly generated surface of the chip formed is exposed to the atmosphere, and as a result, it is easily oxidized. The chip bends due to oxidation of the newly generated surface, and as a result, curls. In addition, as the oxidation of the chip proceeds, the curled diameter of the chip decreases. As the curled diameter decreases, the stress in the chip increases. Thereafter, the internal stress of the chip reaches the fracture strength of the chip, thereby cutting off the chip. As described above, by reducing the frictional resistance between the chip and the front cutting edge 14a, the chip curls up and is eventually cut off.

[0019] Figure 2 This is a diagram of the top end portion of the cutting tool 10 observed along the axial direction. An imaginary plane F containing the axis A0 is set. Here, the front cutting edge 14a is opposite to and parallel to the imaginary plane F. The core height H of the cutting edge 22a is defined with reference to the imaginary plane F. The absolute value of the core height H is determined by the distance of the cutting edge 22a (front cutting edge 14a) from the imaginary plane F. In addition, the positive and negative (positive, negative) of the core height (height from the center axis) H is determined by the position of the cutting edge 22a relative to the imaginary plane F and the rotation direction C. When the cutting edge 22a is located in the direction of the rotation direction C relative to the imaginary plane F, the core height H is positive (+). On the other hand, when the cutting edge 22a is located in the direction opposite to the rotation direction C relative to the imaginary plane F, the core height H is negative (-).

[0020] like Figure 2As shown, in the present embodiment, the rake face 14a is arranged at a position offset from the imaginary plane F in the direction opposite to the rotation direction C of the cutting tool 10. That is, the core height H of the cutting edge 22a is negative (-). This means that the cutting edge 22a is in a so-called core-down state. As described later, in order to make it easier for the chips to extend radially inward I, the core height H is preferably, for example, -0.1 mm to -0.7 mm. In addition, the core height H is more preferably -0.2 mm to -0.5 mm.

[0021] Figure 3 1 is a diagram of the top end portion of the cutting tool 10 viewed in the axial direction. Here, the cutting tool 10 is rotated in the rotation direction C relative to the imaginary plane F until the outer side of the rake face 14a (the boundary between the rake face 14a and the outer peripheral end face 18a) is tangent to the imaginary plane F. In this case, the rake face 14A is inclined in the direction opposite to the rotation direction C toward the axis A0.

[0022] In this way, when the cutting edge 22a is lowered, when the cutting edge portion 12a is cutting, the chips formed by the cutting edge 22 tend to extend radially inward I along the inclined surface of the rake face 14a. Figure 1 When the cutting edge angle θa of the cutting edge 22a shown is less than 60°, the tendency of the chips to extend radially inward I becomes stronger. The cutting edge angle θa refers to the inclination (angle) of the cutting edge 22a (beveled end surface 20a) relative to the surface perpendicular to the axis A0. The cutting edge angle θa is preferably 45° or less.

[0023] like Figure 2 and Figure 3 As shown, by lowering the core of the cutting edge 22a (negative core height H), as shown below, the chips are easily broken and miniaturized. First, as described above, the chips are easy to extend radially inward I. When the chips continue to extend radially inward I, the chips can be cut off by abutting against the shaft portion S, etc. The chips can also be cut off by abutting against the inner wall Wa of the hole portion provided in the workpiece W. Sometimes, the top of the chip extending radially inward I will temporarily return radially outward O. In this case, the chip abuts against the inner wall Wa of the workpiece W and can be cut off. In short, in this embodiment, the chips at least temporarily extend radially inward I. Accordingly, the chips can be miniaturized by abutting against the cutting tool 10 or the workpiece W.

[0024] In contrast, as shown below, when the chips extend radially outward O, the chips tend to become longer. Most of the chips are formed near the outermost periphery of the cutting edge portion 12a. Therefore, when the formed chips extend radially outward O, it is difficult for the chips to abut against the cutting tool 10 and the workpiece W. That is, the chips tend to become longer.

[0025] exist Figure 1In the figure, the cutting edge portions 12b to 12d also have a structure corresponding to the cutting edge portion 12a. That is, the cutting edge portion 12b has a rake face 14b, a top face 16b, a peripheral end face 18b, a cutting edge 22b and a plurality of grooves 24b, but does not have an oblique end face 20. The cutting edge 22b is formed on the boundary between the rake face 14b and the top face 16b. The cutting edge angle θb of the cutting edge 22b is zero. A plurality of grooves 24b are formed along the axial direction A. The cutting edge portion 12c has a rake face 14c, a top face 16c, a peripheral end face 18c, a cutting edge 22c and a plurality of grooves 24c, but does not have an oblique end face 20. The cutting edge 22c is formed on the boundary between the rake face 14c and the top face 16c. The cutting edge angle θc of the cutting edge 22c is zero. The cutting edge portion 12d has a rake face 14d, an outer peripheral end face 18d, an oblique end face 20d, a cutting edge 22d, and a plurality of grooves 24d. The cutting edge 22d is formed at the boundary between the rake face 14d and the oblique end face 20d. In the present embodiment, the cutting edge angle θd is less than 45°.

[0026] Here, the cutting edges 22b, 22c, and 22d are in the same state as the cutting edge 22a, in the core-down state. Therefore, in the cutting edges 22b, 22c, and 22d, the chips are also likely to extend radially inward I. That is, the chips are likely to abut against the cutting tool 10 or the workpiece W, and as a result, they are likely to break and be miniaturized. In addition, as described above, since the tool nose angles θb, θc, and θd are less than 45°, the tendency of the chips from the cutting edges 22b, 22c, and 22d to extend radially inward I becomes stronger.

[0027] As described above, in the present embodiment, when the rake face 14 faces the imaginary plane F including the axis A0 in parallel, the rake face 14 is arranged at a position offset from the imaginary plane F in the direction opposite to the rotation direction C of the cutting tool 10. Accordingly, the chips are likely to extend toward the radial inner side I of the cutting tool 10. As a result, the chips come into contact with the inner wall Wa of the cutting tool 10 or the workpiece W, and are likely to be fined.

[0028] [Modified embodiment]

[0029] The present invention is not limited to the above-mentioned embodiment, and various structures can be adopted without departing from the main purpose of the present invention. In the present embodiment, the number of each of the four types of cutting edge portions 12a to 12d is set to 4, but the number can also be set to 1 to 3 or more than 5. In addition, the number of types of cutting edge portions can also be 1 to 3 or more than 5.

[0030] [Technical solution obtained from implementation method]

[0031] The following describes technical solutions that can be grasped from the above-mentioned embodiments.

[0032] [1] A cutting tool (10) that rotates around an axis (A0), the cutting tool having a cutting edge portion (12), the cutting edge portion having a rake face (14) and a cutting edge (22), the rake face (14) being configured such that when the rake face (14) faces an imaginary plane (F) containing the axis and is parallel thereto, the rake face (14) is located at a position deviating from the imaginary plane in a direction opposite to the direction of rotation of the cutting tool. Accordingly, chips formed by the cutting edge tend to extend along the rake face toward the radial inner side (I) of the cutting tool. As a result, the chips come into contact with the cutting tool or a workpiece and are easily cut off.

[0033] [2] The distance from the imaginary plane to the rake face is greater than 0.1 mm and less than 0.7 mm. The chips formed by the cutting edge are more likely to extend along the rake face toward the radial inner side of the cutting tool. As a result, the chips come into contact with the cutting tool or the workpiece and are easily cut off.

[0034] [3] A plurality of grooves are formed on the rake face, the plurality of grooves having one end reaching the cutting edge and arranged side by side for supplying lubricating fluid to the cutting edge, thereby reducing the contact resistance between the chips and the rake face and making it easier for the chips to curl.

[0035] [4] The plurality of cutting edge portions are arranged along a circumference centered on the axis. Thus, the workpiece can be cut by the plurality of cutting edge portions.

Claims

1. A cutting tool (10) which rotates around an axis (A0), characterized in that: It has a plurality of shaft portions and cutting edge portions (12), wherein: The plurality of shaft portions are arranged at different axial positions; The cutting edge portion has a rake face (14) and a cutting edge (22), and is respectively arranged on the plurality of shaft portions. The plurality of shaft portions include a first shaft portion (Sa), a second shaft portion (Sb), a third shaft portion (Sc) and a fourth shaft portion (Sd), wherein the second shaft portion is disposed at a position closer to the base end than the first shaft portion and has a larger diameter than the first shaft portion; The third shaft portion is disposed at a position closer to the base end than the second shaft portion and has a larger diameter than the second shaft portion; The fourth shaft portion is disposed at a position closer to the base end than the third shaft portion and has a larger diameter than the third shaft portion. The rake face is a surface formed in parallel with the axis, A plurality of grooves are formed on the rake face, the plurality of grooves are arranged side by side and have one end reaching the cutting edge for supplying lubricating liquid to the cutting edge. The plurality of grooves provided in the cutting edge portion of the first shaft portion and the fourth shaft portion are formed to be inclined with respect to the axis. The cutting edge portions provided on the first shaft portion and the fourth shaft portion have oblique end surfaces (20a, 20d) inclined relative to a surface perpendicular to the axis, The plurality of grooves provided in the cutting edge portion of the second shaft portion and the third shaft portion are formed along the axis. The cutting edges (22b, 22c) of the cutting edge portions provided on the second shaft portion and the third shaft portion are parallel to a plane perpendicular to the axis. In each of the plurality of cutting edge portions, the rake face is configured such that when the rake face faces an imaginary plane (F) containing the axis and is parallel to the imaginary plane, the rake face is located at a position deviating from the imaginary plane in a direction opposite to the rotation direction of the cutting tool.

2. The cutting tool according to claim 1, characterized in that A distance (H) from the virtual plane to the rake face is greater than or equal to 0.1 mm and less than or equal to 0.7 mm.

3. The cutting tool according to claim 1 or 2, characterized in that: The plurality of cutting edge portions are arranged along a circumference centered on the axis.

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