Drill for resin and method for manufacturing workpiece

Abstract

To increase processing accuracy of a processed hole in a case of drilling a processed hole having a hole diameter comparatively large or a processed hole having a hole depth comparatively deep, with respect to a material to be cut formed of a resin.SOLUTION: A drill for a resin (10) includes: a cylindrical drill body (12); and a tabular cutting chip (14) formed in a distal end of the drill body (12). At least a portion of the cutting chip (14) is formed in a triangle tabular shape having a point angle (θ).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a resin drill for drilling holes in a workpiece made of resin such as acrylic resin, and to a method for manufacturing a workpiece using the resin drill. [Background technology]

[0002] For example, research and development of metal drills for drilling holes in workpieces made of metal such as steel has progressed, and many types of metal drills are available on the market.In contrast, research and development of resin drills has lagged behind, and only a few types of resin drills are available on the market.

[0003] Incidentally, prior art related to the present invention is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6501374 Summary of the Invention [Problem to be solved by the invention]

[0005] Commercially available resin drills (see Comparative Examples 2 and 3 described below) can accurately drill holes with relatively small diameters (e.g., 3 mm or less) or relatively shallow depths (e.g., 2 mm or less) in resin workpieces. On the other hand, when the hole diameter or depth increases, frictional heat at the tip of the resin drill increases, causing chips to fuse to the tip of the resin drill. As a result, when drilling holes with relatively large diameters (e.g., 6 mm or more) or relatively deep depths (e.g., 5 mm or more) in resin workpieces, the holes tend to be inaccurately round, resulting in reduced drilling accuracy.

[0006] When a metal drill is used to drill holes in a workpiece made of resin, the tip of the metal drill will bite into the workpiece, causing the workpiece to crack or chip.

[0007] Therefore, one aspect of the present invention aims to improve the machining accuracy of holes when drilling holes with a relatively large diameter or a relatively deep hole depth in a workpiece made of resin. [Means for solving the problem]

[0008] To solve the above-mentioned problems, the inventors of the present application utilized their first finding to discover the following second finding, which led to the completion of the present invention. The first finding is that forming the tip of a resin drill into a triangular plate shape reduces frictional heat at the tip of the resin drill, making it difficult for chips to fuse to the tip of the resin drill, even when drilling a relatively large diameter or relatively deep hole in a resin workpiece (see Examples below). The second finding is that having a tip of a resin drill that includes a triangular plate-shaped portion and a rectangular plate-shaped portion connected to the triangular plate-shaped portion improves chip discharge, making it difficult for chips to fuse to the tip of the resin drill, even when drilling a relatively large diameter or relatively deep hole in a resin workpiece (see Examples below).

[0009] A resin drill according to one aspect of the present invention is a resin drill for drilling holes in a workpiece made of resin, and includes a cylindrical drill body that rotates about its axis and a flat cutting tip formed at the tip of the drill body. The drill body has a plurality of chip discharge flutes formed at intervals circumferentially on the outer peripheral surface of the drill body and extending spirally from the tip to the base end of the drill body, and a peripheral cutting edge formed at a ridge between the wall surface of each chip discharge flute facing the rotation direction of the drill body and the outer peripheral surface of the drill body. At least a portion of the cutting tip is formed in a triangular flat plate shape with a point angle. The cutting tip has a first tip surface, a second tip surface located opposite the first tip surface, a pair of tip end surfaces located between the first tip surface and the second tip surface and arranged symmetrically with respect to the axis, a first tip cutting edge formed on the ridge between the first tip surface and one of the tip end surfaces and connected to the peripheral cutting edge, and a second tip cutting edge formed on the ridge between the second tip surface and the other tip end surface and connected to the peripheral cutting edge.

[0010] According to the above configuration, at least a portion of the cutting tip is formed into a triangular flat plate having the point angle. In other words, the tip of the resin drill is formed into a triangular flat plate. Therefore, according to the above-mentioned first novel finding, even when drilling a relatively large hole diameter or a relatively deep hole in a resin workpiece, frictional heat at the tip of the resin drill is reduced, making it difficult for chips to fuse to the tip of the resin drill. As a result, even in the above case, the drilled hole can be formed into an accurate circular shape, thereby improving the drilling accuracy of the drilled hole.

[0011] In one embodiment of the resin drill of the present invention, the cutting tip may have a first portion formed in a triangular flat plate shape having the point angle, and a second portion formed in a rectangular flat plate shape located between the first portion and the tip of the drill body.

[0012] According to the above configuration, the tip of the resin drill has a triangular flat portion and a rectangular flat portion connected to the triangular portion. Therefore, according to the second novel finding, even when drilling a relatively large hole diameter or a relatively deep hole in a workpiece, chip discharge is improved and chips are less likely to fuse to the tip of the resin drill. As a result, even in the above cases, the hole can be formed into a more accurate circular shape, thereby further improving the machining accuracy of the hole.

[0013] In the drill for resin according to one aspect of the present invention, the point angle of the cutting tip may be set to 67 degrees to 73 degrees.

[0014] According to the above configuration, the strength of the tip end of the cutting tip is sufficiently ensured, and chip discharge is improved, making it difficult for chips to fuse to the tip end of the resin drill. As a result, the durability of the resin drill is improved, and even when drilling holes with relatively large diameters or relatively deep holes in a workpiece, the drilling accuracy can be further improved.

[0015] In addition, a method for manufacturing a workpiece according to one embodiment of the present invention is a method for manufacturing a workpiece by drilling a workpiece made of resin, and includes a rotation step of rotating a resin drill according to one embodiment of the present invention, a processing step of bringing the resin drill in a rotating state into contact with the workpiece to drill a hole in the workpiece, and a separation step of separating the resin drill from the workpiece, which is the workpiece after drilling.

[0016] According to the above configuration, even when the workpiece has a machined hole with a relatively large diameter or a relatively deep hole, the machining accuracy of the machined hole can be improved, thereby improving the machining quality of the workpiece. [Effects of the Invention]

[0017] According to one aspect of the present invention, when drilling a hole with a relatively large diameter or a relatively deep hole in a workpiece made of resin, the machining accuracy of the hole can be improved. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic front view of a drill for resin according to an embodiment of the present invention; [Figure 2] 1 is a schematic enlarged front view of a portion of a drill for resin according to an embodiment of the present invention. FIG. [Figure 3] 1 is a schematic enlarged side view of a portion of a drill for resin according to an embodiment of the present invention. FIG. [Figure 4] 1 is a schematic enlarged view of a tip of a drill for resin according to an embodiment of the present invention; [Figure 5] 5A to 5C are schematic diagrams illustrating a rotation step in the manufacturing method of the workpiece according to the embodiment of the present invention. [Figure 6] 1A to 1C are schematic diagrams illustrating a processing step in a method for manufacturing a processed product according to an embodiment of the present invention. [Figure 7] 5A to 5C are schematic diagrams illustrating a separation step in the manufacturing method of the workpiece according to the embodiment of the present invention. [Figure 8] 10 is a photograph showing the results of processing tests in the example and comparative examples 1 to 3. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] [Resin Drill 10] A resin drill 10 according to an embodiment of the present invention will be described with reference to Figs. 1 to 4. Fig. 1 is a schematic front view of the resin drill 10 according to an embodiment of the present invention. Fig. 2 is a schematic enlarged front view of a portion of the resin drill 10 according to an embodiment of the present invention. Fig. 3 is a schematic enlarged side view of a portion of the resin drill 10 according to an embodiment of the present invention. Fig. 4 is a schematic enlarged view of the resin drill 10 according to an embodiment of the present invention as seen from the tip.

[0021] (Outline of resin drill 10, drill body 12, cutting tip 14) As shown in FIGS. 1 to 3, a resin drill 10 according to an embodiment of the present invention is a cutting tool for drilling a workpiece W (see FIG. 5) made of a resin such as an acrylic resin. The resin drill 10 is made of a hard material such as high-speed tool steel or a superalloy. The resin drill 10 is rotatable about its axis CS. By drilling using the resin drill 10, a machined hole H (see FIGS. 6 and 7) is formed in the workpiece W.

[0022] The resin drill 10 includes a cylindrical drill body 12 that rotates about its axis CS, and a flat cutting tip 14 formed at the tip of the drill body 12. The cutting tip 14 is formed integrally with the drill body 12, but may also be formed separately from the drill body 12. In other words, the cutting tip 14 may be joined to the tip of the drill body 12 by welding or the like.

[0023] (Shank part 16, chip discharge groove 18, sub-chip discharge groove 20) As shown in Figures 1 to 4, the drill body 12 has a shank portion 16 at its base end which is attached to a chuck portion of a drill press (not shown) or a drill driver (not shown). The outer diameter of the portion of the drill body 12 excluding the shank portion 16 gradually decreases slightly from the tip end toward the base end. A pair of chip discharge grooves 18 for discharging chips are formed at intervals in the circumferential direction on the outer peripheral surface 12p of the drill body 12 on the tip side of the shank portion 16. Each chip discharge groove 18 spirals from the tip end of the drill body 12 toward the base end. The pair of chip discharge flutes 18 are arranged rotationally symmetrically about the axis CS of the drill body 12 when viewed from the tip of the resin drill 10.

[0024] A secondary chip discharge flute 20 for discharging chips is formed between the pair of chip discharge flutes 18 on the outer peripheral surface 12p of the drill body 12. Each secondary chip discharge flute 20 extends spirally from the tip end toward the base end of the drill body 12. When viewed from the tip end of the resin drill 10, the pair of secondary chip discharge flutes 20 are arranged rotationally symmetrically about the axis CS of the drill body 12.

[0025] (Peripheral blade 22) A peripheral cutting edge 22 is formed on the ridge between a wall surface 18f of each chip flute 18 facing the rotation direction T of the drill body 12 and the outer peripheral surface 12p of the drill body 12. The wall surface 18f of each chip flute 18 facing the rotation direction T of the drill body 12 becomes the rake face of each peripheral cutting edge 22. The portion of the outer peripheral surface 12p of the drill body 12 adjacent to each peripheral cutting edge 22 becomes the relief face of each peripheral cutting edge 22.

[0026] (1st part P1, 2nd part P2) As shown in FIGS. 2 and 3 , the cutting tip 14 has a first portion P1 formed in the shape of an isosceles triangular plate having a point angle θ, and a second portion P2 formed in the shape of a rectangular plate and located between the first portion P1 and the tip of the drill body 12. The tip of the first portion P1 of the cutting tip 14 is located at the axis CS of the drill body 12. The thickness of the cutting tip 14 gradually decreases from the base end side toward the tip end side of the cutting tip 14. Note that although the first portion P1 of the cutting tip 14 is formed in the shape of an isosceles triangular plate, it may also be formed in the shape of a triangular plate other than an isosceles triangle. The second portion P2 may be omitted from the cutting tip 14, so that the cutting tip 14 consists only of the first portion P1.

[0027] (First chip surface 14a, second chip surface 14b, chip end surface 14c) 2 to 4, the cutting tip 14 has a first tip surface 14a, a second tip surface 14b located on the opposite side of the first tip surface 14a, and a pair of tip end surfaces 14c located between the first tip surface 14a and the second tip surface 14b. The pair of tip end surfaces 14c are arranged symmetrically with respect to the axis CS of the drill body 12 (the axis of the resin drill 10).

[0028] (First tip blade 24, second tip blade 26) 2 to 4, a first tip cutting edge 24 is formed at the ridge between the first tip surface 14a and one tip end surface 14c of the cutting tip 14. The first tip cutting edge 24 is smoothly connected to one peripheral cutting edge 22. The first tip surface 14a of the cutting tip 14 forms the rake face of the first tip cutting edge 24, and one tip end surface 14c of the cutting tip 14 forms the relief face of the first tip cutting edge 24.

[0029] A second tip cutting edge 26 is formed at the ridge between the second tip surface 14b and the other tip end surface 14c of the cutting tip 14. The second tip cutting edge 26 is smoothly connected to the other peripheral cutting edge 22. The second tip surface 14b of the cutting tip 14 forms the rake face of the second tip cutting edge 26, and the other tip end surface 14c of the cutting tip 14 forms the relief face of the second tip cutting edge 26.

[0030] (Point angle θ of first portion P1) The tip angle θ of the first portion P1 of the cutting tip 14 is set to 67 degrees to 73 degrees. The reason why the tip angle θ of the first portion P1 of the cutting tip 14 is set to 67 degrees or more is that when the tip angle θ is 67 degrees or more, the strength of the tip side of the first portion P1 of the cutting tip 14 is sufficiently ensured, and the first tip This is because chipping or the like of the cutting edge 24 or the second tip cutting edge 26 is less likely to occur. The reason why the tip angle θ of the first portion P1 of the cutting tip 14 is set to 73 degrees or less is because a tip angle θ of 73 degrees or less improves the dischargeability of chips, making it less likely for the chips to adhere to the tip of the resin drill 10.

[0031] [Actions and Effects of the Resin Drill 10] Next, the effects of the resin drill 10 according to the embodiment of the present invention will be described.

[0032] As described above, in the resin drill 10, the first portion P1 of the cutting tip 14 is formed in the shape of an isosceles triangular plate having a point angle θ. In other words, the tip of the resin drill 10 is formed in the shape of an isosceles triangular plate. Therefore, according to the first novel finding described above, even when drilling a hole H having a relatively large diameter (e.g., a hole diameter of 6 mm or more) or a relatively deep hole H (e.g., a hole depth of 5 mm or more) in a workpiece W made of a resin such as acrylic resin, frictional heat at the tip of the resin drill 10 is reduced, making it difficult for chips to fuse to the tip of the resin drill 10. As a result, even in the above case, the hole H can be formed into an accurate circular shape, thereby improving the drilling accuracy of the hole.

[0033] As described above, the cutting tip 14 of the resin drill 10 has a first portion P1 formed in the shape of an isosceles triangle plate and a second portion P2 formed in the shape of a rectangular plate and located between the first portion P1 and the tip of the drill body 12. In other words, the tip of the resin drill 10 has a triangular plate-like portion and a rectangular plate-like portion continuous therewith. Therefore, according to the second novel finding described above, even when drilling a hole H having a relatively large diameter or a relatively deep hole H in a workpiece W, chip discharge is improved, and chips are less likely to fuse to the tip of the resin drill 10. As a result, even in the above case, the hole H can be formed into a more accurately circular shape, thereby improving the machining accuracy of the hole H.

[0034] Furthermore, in the resin drill 10, as described above, the point angle θ of the first portion P1 of the cutting tip 14 is set to 67 degrees to 73 degrees. Therefore, while the strength of the tip side of the cutting tip 14 is sufficiently ensured, the chip discharge performance is improved, and the chips are less likely to fuse to the tip portion of the resin drill 10. Therefore, this increases the durability of the resin drill 10, and also makes it possible to further improve the machining accuracy of the machined hole H, even when drilling a machined hole H with a relatively large hole diameter or a relatively deep hole depth in a workpiece W.

[0035] [Method for manufacturing processed products] Next, a method for manufacturing a workpiece according to an embodiment of the present invention will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is a schematic diagram illustrating a rotation step in the method for manufacturing a workpiece according to an embodiment of the present invention. Fig. 6 is a schematic diagram illustrating a processing step in the method for manufacturing a workpiece according to an embodiment of the present invention. Fig. 7 is a schematic diagram illustrating a separation step in the method for manufacturing a workpiece according to an embodiment of the present invention.

[0036] (Outline of manufacturing method for processed products) As shown in Figures 5 to 7, the method for manufacturing a workpiece according to an embodiment of the present invention is a method for manufacturing a workpiece M by drilling a workpiece W made of a resin such as an acrylic resin. The manufacturing method according to an embodiment of the present invention includes a rotating step, a processing step, and a separating step. The specific contents of each step according to an embodiment of the present invention are as follows.

[0037] (Rotation process) As shown in FIG. 5, the shank portion 16 of the drill body 12 of the resin drill 10 is attached to the chuck portion of a drill press (not shown) or a drill driver (not shown). The resin drill 10 (drill body 12) is driven to rotate around its axis CS.

[0038] (Processing process) 5 and 6, the rotating resin drill 10 is moved relative to the workpiece W in the direction of the arrow F1 to contact the workpiece W. The rotating resin drill 10 is then moved relative to the workpiece W in the direction of the arrow F1 to drill the workpiece W. This allows a machined hole H to be formed in the workpiece W.

[0039] (Separation process) 6 and 7, the resin drill 10 is then moved in the direction of the arrow F2 relative to the workpiece M, which is the workpiece W that has already been drilled, and is moved away from the workpiece M. This completes the manufacture of the workpiece M.

[0040] (Effects of the manufacturing method for processed products) Next, the effects of the method for manufacturing a workpiece according to the embodiment of the present invention will be described.

[0041] The method for manufacturing a workpiece according to an embodiment of the present invention uses the resin drill 10 having the above-described configuration. Therefore, even when the workpiece M has a machined hole H with a relatively large diameter (e.g., a hole diameter of 6 mm or more) or a relatively deep hole depth (e.g., a hole depth of 5 mm or more), the machining accuracy of the machined hole H can be improved, thereby improving the machining quality of the workpiece M. [Example]

[0042] An example of the present invention will be described with reference to Fig. 8. Fig. 8 is a photograph showing the results of processing tests in the example and comparative examples 1 to 3.

[0043] As shown in Figure 8, a drill 10 (see Figure 1) for resin with a drill diameter of 12 mm was prepared as a prototype drill according to the example. In addition, a plate drill bit (itagiri) with a drill diameter of 12 mm manufactured by Kanzawa Iron Works Co., Ltd. was purchased as the drill according to Comparative Example 1. An acrylic drill bit with a drill diameter of 12 mm manufactured by Acrylic Sunday Co., Ltd. was purchased as the drill according to Comparative Example 2. A drill bit for plastic manufactured by Star-M Co., Ltd. was purchased as the drill according to Comparative Example 3.

[0044] Then, a machining test was conducted to drill holes in an extruded acrylic plate having a thickness of 10 mm as a workpiece using the drill according to the example and the drills according to comparative examples 1 to 3. The results of the machining test for the example and comparative examples 1 to 3 are as follows.

[0045] 8, in the case of Comparative Example 1, since the tip portion of the drill according to Comparative Example 1 is thin-plate shaped, the temperature (cutting temperature) of the tip portion of the drill according to Comparative Example 1 is 48.2°C, and it was found that it is possible to reduce frictional heat at the tip portion of the drill according to Comparative Example 1. On the other hand, since the drill according to Comparative Example 1 has a thin shaft shape other than the tip portion, the drill according to Comparative Example 1 is prone to wobbling and was unable to form an accurately circular drilled hole.

[0046] In the case of Comparative Example 2, the temperature at the tip of the drill according to Comparative Example 2 reached 83.4°C, and it was found that frictional heat was large at the tip of the drill according to Comparative Example 2. In addition, chips fused to the tip of the drill according to Comparative Example 2, making the machined surface of the drilled hole unstable and failing to form an accurate circular drilled hole.

[0047] In the case of Comparative Example 3, the temperature at the tip of the drill according to Comparative Example 3 reached 56.8°C, indicating that frictional heat was large at the tip of the drill according to Comparative Example 3. In addition, chips fused to the tip of the drill according to Comparative Example 4, making the machined surface of the drilled hole unstable and failing to form an accurate circular drilled hole.

[0048] In contrast, in the case of the example, the temperature at the tip of the drill according to the example became 33.2°C, and it was found that the frictional heat at the tip of the drill according to the example could be sufficiently reduced. In addition, chips were less likely to fuse to the tip of the drill according to the example, making it possible to form a precisely circular machined hole and improving the machining accuracy of the machined hole.

[0049] In other words, the results of the above-mentioned machining tests showed that by forming the tip of the drill into a triangular flat plate shape, frictional heat at the tip of the drill is reduced and chips are less likely to fuse to the tip of the drill, even when drilling holes of relatively large diameter or relatively deep depth in a workpiece made of resin.Furthermore, by having a drill tip with a triangular flat plate portion and a rectangular flat plate portion connected to it, chip discharge is improved and chips are less likely to fuse to the tip of the resin drill, even in the above-mentioned cases.

[0050] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0051] 10 Resin drill 12 Drill body 12p outer surface 14 Cutting tip 14a First chip surface 14b Second chip surface 14c Chip end face 16 Shank 18 Chip discharge groove 18f Wall facing the direction of rotation 20 Sub-chip discharge groove 22 Peripheral blade 24 First cutting edge 26 Second cutting edge P1 1st part P2 2nd part θ Tip angle W Work material M Workpiece

Claims

1. A resin drill for drilling holes in a workpiece made of resin, A cylindrical drill body that rotates around its axis; a flat cutting tip formed at the tip of the drill body, The drill body includes: a plurality of chip discharge flutes formed at intervals in the circumferential direction on the outer peripheral surface of the drill body and extending spirally from the tip end toward the base end of the drill body; a peripheral cutting edge formed on a ridge line between a wall surface of each chip discharge flute facing the rotation direction of the drill body and the outer peripheral surface of the drill body, At least a portion of the cutting tip is formed in a triangular flat plate shape having a tip angle, The cutting tip is a first chip surface; a second chip surface located opposite the first chip surface; a pair of tip end faces located between the first tip face and the second tip face and arranged symmetrically with respect to the axis; a first tip cutting edge formed on a ridge between the first tip surface and one of the tip end surfaces and connected to the peripheral cutting edge; a second tip cutting edge formed on a ridge between the second tip surface and the other tip end surface and connected to the peripheral cutting edge, The cutting tip is a first portion formed in a triangular flat plate shape having the tip angle; a second portion formed in a rectangular plate shape and located between the first portion and the tip of the drill body, The drill for resin, wherein the point angle of the cutting tip is set to 67 degrees to 73 degrees.

2. A method for manufacturing a workpiece by drilling a workpiece made of resin, comprising: a rotating step of rotating the resin drill according to claim 1; a processing step of bringing the rotating resin drill into contact with a workpiece to drill a hole in the workpiece; and a separating step of separating the resin drill from a workpiece, which is a workpiece material that has already been drilled.

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