Cutting tools

Abstract

The present invention aims to provide a cutting tool that can perform drilling operations like a drill, and also perform side machining operations like an end mill. [Solution] The cutting tool according to the present invention is a cutting tool 1 that rotates around an axis TT, and comprises a tip portion 10 on which a tip cutting edge 11 is formed, and a main body portion 20 connected to the rear end side of the tip portion 10 and having a spiral chip discharge groove 21 formed around the axis, wherein an outer peripheral cutting edge 23 is formed on the main body portion 20 along a leading edge 22, and a plurality of inner grooves 25 are formed on the inner surface of the chip discharge groove 21 so as to be inclined toward the rear end side and intersect with the outer peripheral cutting edge 23 on the rake face of the outer peripheral cutting edge 23.

Description

Technical Field

[0001] The present invention relates to a cutting tool that has a function of drilling holes like a drill and also has a function of side surface machining like an end mill.

Background Art

[0002] Conventionally, a drill has been used for drilling holes in a workpiece, and an end mill has been used for shape machining such as groove machining and side surface machining of the workpiece. In a drill, cutting is performed by a tip cutting edge, and the chips are guided into a spiral groove and discharged from the hole to the outside. In an end mill, cutting is performed by a tip cutting edge and cutting edges formed spirally on the outer periphery, and the chips are discharged to the outside.

[0003] For drills and end mills, various types have been proposed according to the material of the workpiece and the machining conditions. For example, in Patent Document 1, a tip portion formed with a tip cutting edge, a taper portion formed in a taper shape connected to the rear end side of the tip portion, and a straight portion having the same diameter as or larger than the outer diameter of the rear end side of the taper portion formed by connecting to the rear end side of the taper portion are provided. On the outer periphery of the taper portion, a chip discharge groove twisted spirally is formed, and a composite material drill having an outer peripheral cutting edge formed along the edge on the straight portion side of the chip discharge groove is described.

[0004] Also, in Patent Document 2, a rotary tool is described in which a discharge groove and a ridge line are formed on the outer peripheral surface of a cylindrical main body, and a blade portion formed on the ridge line is divided by a plurality of dividing grooves.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] Patent Document 1 describes a tool that, in addition to a cutting edge at the tip, has an outer cutting edge for drilling holes in composite materials. However, it cannot be used for side machining or other processes like an end mill, and only has the function of drilling holes. Patent Document 2 describes a tool that has functions such as side machining like an end mill, but when used for drilling holes like a drill, it is impractical because chip removal from the hole is difficult.

[0007] With conventional cutting tools, it is difficult to give drills used for drilling the same functionality as end mills. While end mills are sometimes used for drilling, they have drawbacks in terms of machining stability and chip evacuation.

[0008] Therefore, the present invention aims to provide a cutting tool that can perform drilling operations like a drill and side machining operations like an end mill. [Means for solving the problem]

[0009] The cutting tool according to the present invention is a cutting tool that rotates around an axis, comprising a tip portion having a cutting edge formed thereon, and a main body portion connected to the rear end side of the tip portion and having a spiral chip discharge groove formed around the axis, wherein the main body portion has an outer peripheral cutting edge formed along the leading edge, and on the inner surface of the chip discharge groove, a plurality of inner grooves are formed on the rake face of the outer peripheral cutting edge so as to be inclined toward the rear end side and intersect with the outer peripheral cutting edge. Furthermore, the outer peripheral cutting edge is formed in a wavy curved shape so as to be concave at the portion that intersects with the inner grooves. Furthermore, the inner grooves are formed to widen toward the outer peripheral cutting edge and communicate with adjacent inner grooves. Furthermore, the inner groove adjacent to the tip cutting edge is formed by cutting out the tip cutting edge. Furthermore, the inner grooves are deepened by scooping out at the side edge on the rear end side, forming a step. [Effects of the Invention]

[0010] The present invention has a tip portion with a cutting edge formed thereon and a main body portion with a spiral chip evacuation groove formed thereon, so it can perform drilling operations like a drill, and it has an outer peripheral cutting edge formed along the leading edge of the main body portion so it can perform side machining operations like an end mill.

[0011] Furthermore, multiple internal grooves are formed on the inner surface of the chip discharge groove, inclined toward the rear end and intersecting with the outer cutting edge on the rake face of the outer cutting edge. As a result, chips introduced into the chip discharge groove are broken into smaller pieces by the internal grooves and discharged smoothly, enabling efficient drilling and side machining. [Brief explanation of the drawing]

[0012] [Figure 1] This is an external perspective view of a cutting tool, which is an embodiment of the present invention. [Figure 2] Figure 1 shows a front view and a side view of the tip of the drill. [Figure 3] Figure 2 shows cross-sectional views AA and BB. [Figure 4] Figure 1 is an enlarged view of the tip portion of the cutting tool. [Figure 5] This is an explanatory diagram showing how to perform drilling using a cutting tool. [Figure 6] This is an explanatory diagram showing how to perform side machining using a cutting tool. [Modes for carrying out the invention]

[0013] The embodiments of the present invention will be described in detail below. While the embodiments described below are preferred examples for carrying out the present invention and therefore have various technical limitations, the present invention is not limited to these forms unless specifically stated in the following description to limit the present invention.

[0014] FIG. 1 is an external perspective view of a cutting tool 1 according to an embodiment of the present invention. FIG. 2 is a front view (FIG. 2(a)) and a side view (FIG. 2(b)) of the tip portion of the drill shown in FIG. 1.

[0015] The cutting tool 1 is configured to perform cutting while rotating around an axis T-T, and includes a tip portion 10 formed with a pair of tip cutting edges 11, a main body portion 20 connected to the rear end side of the tip portion 10 and formed with spiral chip discharge grooves 21 around the axis T-T, and a cylindrical shank portion 30 connected to the rear end side of the main body portion 20.

[0016] The tip portion 10 is formed with a pair of tip cutting edges 11 radially around the axis T-T, and is set to a predetermined tip angle with the center as a tip. Inside the tip cutting edge 11, a curved rake face is formed and communicates with the chip discharge groove 21, and a relief face 12 is formed connected to the outside of the tip cutting edge 11.

[0017] By pressing the tip portion 10 against the workpiece and rotating the cutting tool 1 around the axis T-T, the tip cutting edge 11 cuts the workpiece to perform circular drilling.

[0018] The main body portion 20 is formed with a pair of spiral chip discharge grooves 21 communicating with the rake face of the tip portion 10 with a predetermined width around the axis T-T, and the chips generated by cutting with the tip cutting edge 11 are guided to the chip discharge grooves 21 and move toward the rear end side and are discharged to the outside.

[0019] An outer peripheral cutting edge 23 is formed on a leading edge 22 which is one edge portion of each of the pair of chip discharge grooves 21, and a margin 24 is formed with a predetermined width from the edge. A plurality of inner grooves 25 are formed in a curved surface portion which becomes the rake face of the outer peripheral cutting edge 23 on the groove surface of the chip discharge groove 21. The pair of outer peripheral cutting edges 23 are formed with their respective front ends contacting the outer ends of the pair of tip cutting edges 11.

[0020] The inner groove 25 is formed to be inclined toward the rear end side and intersect with the outer peripheral cutting edge 23, and is formed to expand toward the outer peripheral cutting edge 23 so as to communicate with an adjacent inner groove 25 in the vicinity of the outer peripheral cutting edge 23. The outer peripheral cutting edge 23 is formed in a wavy curve shape with a recessed intersection portion with the inner groove 25.

[0021] FIG. 3 is a cross-sectional view taken along the line A-A (FIG. 3(a)) and a cross-sectional view taken along the line B-B (FIG. 3(b)) of FIG. 2. The A-A cross-section is a cutting plane orthogonal to the axis T-T at the wavy peak portion of one of the pair of outer peripheral cutting edges 23 (the front side in FIG. 2), and the B-B cross-section is a cutting plane orthogonal to the axis T-T at the wavy valley portion. The pair of outer peripheral cutting edges 23 are formed such that the peak portion and the valley portion of the wavy curve shape are shifted from each other in the direction of the axis T-T, and the peak portion of one outer peripheral cutting edge 23 is set to correspond to the valley portion of the other outer peripheral cutting edge 23.

[0022] Since the peak portion and the valley portion of the pair of outer peripheral cutting edges 23 have corresponding shapes, when the cutting tool is rotated and the side surface of the workpiece is cut by the outer peripheral cutting edge 23, the portion cut by the valley portion is cut by the peak portion, and by alternately cutting the cutting portions by the peak portion and the valley portion, the cutting surface can be finished uniformly.

[0023] Each inner groove 25 becomes deeper so as to pinch at the side edge on the rear end side, and a step 25a is formed, and becomes shallower toward the front end side, and a gentle inclined surface is formed. FIG. 4 is an enlarged view of the tip portion of the cutting tool shown in FIG. 1, and shows the shape of the inner groove 25 by gradation.

[0024] By forming the inner groove 25 in such a shape, when the chips generated by cutting with the outer peripheral cutting edge 23 are guided toward the rear end side in the chip discharge groove 21, they move into the inner groove 25, contact the step 25a, and break, so that the chips are cut into small pieces and can be efficiently moved and discharged in the chip discharge groove 21.

[0025] The internal groove 25 adjacent to the cutting edge 11 extends toward the cutting edge 11, and a portion of the cutting edge 11 is notched (see Figure 2(a)). By forming a notch in the cutting edge 11, the tip portion 10 is restrained during cutting, allowing the tip portion 10 to rotate without wobbling and perform stable cutting operations.

[0026] Furthermore, the chips generated by cutting with the cutting edge 11 are guided towards the rear end through the chip discharge groove 21. As the chips move within the inner groove 25, they come into contact with the step 25a, causing them to break into smaller pieces, which can then be efficiently moved and discharged within the chip discharge groove 21.

[0027] The pitch and curvature of the wavy curved shape of the outer cutting edge 23 can be adjusted as appropriate according to machining conditions such as the material of the workpiece. Similarly, the pitch and shape of the inner groove 25 can also be changed as appropriate according to machining conditions.

[0028] Figure 5 is an explanatory diagram showing how to perform drilling using a cutting tool. In drilling, the cutting tool 1 rotates around its axis TT, pressing its tip against the surface of the workpiece M to form a hole H.

[0029] By pressing the tip of the cutting tool 1 against the surface of the workpiece M, the rotating cutting edge 11 begins to perform a cutting motion. The chips generated by the cutting motion are guided towards the rear end within the chip discharge groove 21, as indicated by the arrow.

[0030] As the chips move within the chip discharge groove 21, they move within the inner groove 25 and come into contact with the step 25a, causing them to break into smaller pieces and be efficiently discharged. As a result, drilling can be performed stably and efficiently.

[0031] Figure 6 is an explanatory diagram showing the process of performing side machining using a cutting tool. In side machining, the cutting tool 1 rotates around its axis TT, pressing its main body against the workpiece surface M, and moves along the workpiece surface to form the side P.

[0032] By pressing the outer cutting edge 23 of the cutting tool 1 against the workpiece surface M and rotating it, the outer cutting edge 23 performs a cutting action. The chips generated by the cutting action are split at the peaks and valleys due to the wavy curved shape of the outer cutting edge 23. The split chips then move within the chip discharge groove 21, and as they move within the inner groove 25, they come into contact with the step 25a, causing the chips to break into smaller pieces and be efficiently discharged. As a result, side machining can be performed stably and efficiently. [Industrial applicability]

[0033] This invention allows for drilling operations like a drill using the tip portion with a cutting edge, and for side milling operations like an end mill using the outer cutting edge formed along the leading edge of the main body. Therefore, it is possible to perform cutting processes that were previously carried out with multiple cutting tools such as drills and end mills using a single cutting tool, thereby shortening processing time and significantly improving work efficiency compared to conventional methods. [Explanation of Symbols]

[0034] 1...Cutting tool, 10...Tip section, 11...Cutting edge at tip, 12...Flap surface, 20...Body section, 21...Chip evacuation groove, 22...Leading edge, 23...Outer cutting edge, 24...Margin, 25...Inner groove, 25a...Step, 30...Shank section

Claims

1. A cutting tool that rotates around an axis, comprising a tip portion having a cutting edge formed thereon, and a main body portion connected to the rear end of the tip portion and having a spiral chip discharge groove formed around the axis, wherein the main body portion has an outer cutting edge formed along the leading edge, and the inner surface of the chip discharge groove has a plurality of inner grooves formed on the rake face of the outer cutting edge so as to be inclined toward the rear end and intersect with the outer cutting edge.

2. The cutting tool according to claim 1, wherein the outer cutting edge is formed in a wavy curved shape so as to be concave at the intersection with the inner groove.

3. The cutting tool according to claim 1 or 2, wherein the internal groove is formed to widen toward the outer cutting edge and communicates with an adjacent internal groove.

4. The cutting tool according to claim 1 or 2, wherein the inner groove adjacent to the cutting edge is formed by cutting out the cutting edge.

5. The cutting tool according to claim 1 or 2, wherein the internal groove deepens at the rear end side edge, creating a step.

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