JP2009018382A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill capable of reducing a load applied to the drill when a deep hole is cut for example, and keeping a long service life of a tool, and in addition capable of smoothly discharging chips. <P>SOLUTION: The drill 10 includes a blade 12 having spiral cutting edges 16 and 18 formed to extend along a cutting direction from a tip to a tail, and a shank 14 formed continuously with the tail of the blade 12. The blade 12 has tip cutting edges 16a and 18a formed along the cutting direction from the tip of the blade 12 with a certain helix angle α1, intermediate grooves 16b and 18b formed by a helix angle αx gradually varying from the first helix angle α1 to a second helix angle α2, and a tail grooves 16c and 18c formed by the certain helix angle α2. The tail grooves 16c and 18c are specified to be longer in lengths in the cutting direction than those of the tip cutting edges 16a and 18a, and in addition, the second helix angle α2 is specified to be larger than the first helix angle α1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drill for making a hole in, for example, an engine component.

  For example, when continuously producing engine parts made of aluminum casting that require a process of cutting a deep hole, a large load is applied to the drill that performs the cutting, so a drill suitable for cutting the deep hole is suitable. Is used for processing.

  In Patent Document 1, as a drill suitable for deep hole drilling in metal, the entire length or a part of the twist angle of the blade part is continuously changed, and the twist angle on the front end side of the blade part is set on the rear end side. A drill larger than the twist angle is disclosed. It is described that this improves the sharpness of the drill and further increases the rigidity of the drill.

Japanese Utility Model Publication No. 53-38953

  By the way, in this type of drill, the strength of the drill, such as bending strength, so-called rigidity, cutting resistance (cutting reaction force), chip shape, dischargeability, and the like vary depending on the size of the twist angle. Accordingly, the drill life is also affected by the setting condition of the torsion angle. In particular, in the case of a drill used for deep hole drilling, the load applied to the drill at the time of cutting becomes extremely large, and it becomes difficult to discharge chips at the deep part of the deep hole, so the drill breaks due to clogged chips. There is also a possibility to do.

  The present invention has been made in consideration of the above-described conventional problems. For example, even when a deep hole is cut, the load applied to the drill can be reduced and the tool life can be maintained longer. It aims at providing the drill which can discharge | emit smoothly.

  The drill according to the present invention includes a blade portion in which a spiral cutting blade is formed along a cutting direction from the front end side toward the rear end side, and a shank portion formed continuously on the rear end side of the blade portion. The blade portion is provided along the cutting direction from the tip of the blade portion, and a tip-side cutting blade formed at a constant first twist angle, and the tip-side cutting blade from the tip-side cutting blade An intermediate groove formed along a cutting direction and having a twist angle gradually changing from the first twist angle to the second twist angle along the cutting direction; and continuous along the cutting direction from the intermediate groove. A rear end side groove formed at a constant second twist angle, and the rear end side groove is set to be longer in the cutting direction than the front end side cutting edge, and the first The two twist angles are set to be larger than the first twist angle.

  According to such a configuration, the rear end side groove is set to have a larger formation distance and twist angle than the front end side cutting edge, so that chips can be generated smaller in the front end side cutting edge. Moreover, the chips can be efficiently discharged in the rear end side groove. Therefore, particularly when a deep hole is cut in the workpiece, chips can be discharged well even from a deep portion of the deep hole. As a result, it is possible to effectively prevent clogging of chips in the middle of the hole being cut, reduce the load on the drill, and maintain a long tool life. Further, in the rear end side groove formed longer than the front end side cutting edge, the chip discharge speed is improved, and therefore an increase in resistance due to clogging of the chip can be prevented.

  Further, it is preferable that diamond is provided at the tip of the blade portion because chip dischargeability is further improved and wear resistance of the blade edge is also improved.

  Furthermore, an oil passage that penetrates from the front end to the rear end along the axial direction is formed in the drill, and the oil passage is formed by one from the shank portion side to the position where the intermediate groove is formed. At the same time, after branching into two at the position where the intermediate groove is formed and opening at two locations on the tip surface of the blade, the oil passage is in the axial position in most of the axial direction of the drill. Since only one is passed, the flow resistance of the cutting oil in the oil passage can be reduced.

  According to the present invention, since the rear end side groove is set to have a larger formation distance and twist angle than the front end side cutting edge of the blade portion, chips can be generated small in the front end side cutting edge. The chips can be efficiently discharged in the rear end side groove. Therefore, especially when cutting a deep hole in the workpiece, chips can be discharged well even from the deep part of the deep hole, effectively preventing chips from clogging in the middle of the hole being cut. Thus, the load on the drill can be reduced, and the tool life can be maintained long.

  Hereinafter, preferred embodiments of the drill according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a drill 10 according to an embodiment of the present invention, FIG. 2A is a side view of the drill 10 shown in FIG. 1, and FIG. 2B is a blade portion of the drill 10 shown in FIG. It is explanatory drawing which shows the change of a twist angle. The drill 10 according to the present embodiment can be suitably used when a deep hole is cut in a metal part that is a workpiece. Examples of the workpiece include a cylinder block that is an engine component made of aluminum. The In this case, the deep hole is, for example, a hole whose depth is 5 times or more of the drill outer diameter, and 30 times or more when deep, that is, a drill that is a cutting tool in such deep hole cutting. A large load will be generated. Needless to say, the drill 10 can also be used effectively for cutting other than such deep holes, for example, relatively shallow holes and cast holes.

  As shown in FIGS. 1 and 2A, a drill 10 according to the present embodiment includes a blade portion 12 that performs a cutting process on a workpiece, and a shank portion 14 provided on the rear end side of the blade portion 12. Yes. The shank portion 14 is a portion that is gripped by a chuck or the like of a rotational drive source provided in a machine tool (not shown) when the drill 10 is used.

  Two cutting edges 16 and 18 are spirally formed in the blade portion 12 along a cutting direction (axial direction) from the front end side to the rear end side of the drill 10. As shown in FIGS. 1, 3A, and 3C, the cutting edges 16 and 18 extend spirally from the front end side to the rear end side in a state of being arranged symmetrically with respect to the axial direction of the drill 10. is doing. In this case, one cutting blade 16 is continuous with the blade surface 17a located on the front side in the rotation direction of the drill 10 (the direction of arrow A in FIG. 3A) and the rear side of the blade surface 17a. A projecting surface 17b constituting a radial surface, first and second inclined surfaces 17c and 17d continuous from the projecting surface 17b, and a wall surface 17e continuous from the second inclined surface 17d to the blade surface 19a of the other cutting blade 18. It consists of and. Similarly, the other cutting edge 18 includes a blade surface 19a, a protruding surface 19b, a first inclined surface 19c, a second inclined surface 19d, and a wall surface 19e. As can be understood from FIG. 3A, in the cutting edges 16 and 18, rake angles are provided on the blade surfaces 17 a and 19 a that are actually cut into the workpiece.

  The tip surface 20 of the blade portion 12 has a conical shape centering on the apex (chisel point) 20a that is the foremost end of the drill 10 (see FIGS. 3B and 3C), and in the side view shown in FIG. The fan has a predetermined angle θ (for example, 140 °) centered on 20a. Thus, when the angle θ is an obtuse angle, the cutting reaction force (radial reaction force) in the rotation direction of the drill 10 can be reduced. As can be understood from FIGS. 3A and 3C, the tip surface 20 includes a first tip inclined surface 22 a, a second tip inclined surface 22 b, and a third tip inclined surface that are inclined from the apex 20 a toward the one cutting edge 16. 22c and the first tip inclined surface 24a, the second tip inclined surface 24b, and the third tip inclined surface 24c inclined in the direction of the other cutting edge 18 are formed in the above-described cone shape. . Each of the tip inclined surfaces 22a to 22c and 24a to 24c is continuous to the cutting edges 16 and 18 with a predetermined angle.

  In such a tip surface 20, openings 26a and 26b are respectively formed in the second tip inclined surfaces 22b and 24b provided at symmetrical positions across the vertex 20a (see FIGS. 3A and 3C). These openings 26 a and 26 b are openings on the front end side of the oil passage 28 that penetrates from the front end to the rear end along the axial direction of the drill 10. That is, as shown in FIG. 2A, the oil passage 28 penetrates the drill 10 along the axial direction from the opening on the rear end surface of the shank portion 14, and 1 at a branch point 28 a provided near the tip. After branching from a book into two (Y-shaped), it communicates with the openings 26a and 26b.

  Further, in the blade portion 12, between the cutting blades 16 and 18 extending spirally as described above, workpiece chips cut by the blade surfaces 17a and 19a of the cutting blades 16 and 18 are transferred to the blade portion. Chip discharge grooves 30 and 32 for transferring to the shank portion 14 side, which is the rear end side of 12, are formed. That is, as shown in FIG. 3A, the chip discharge groove 30 is formed by the blade surface 17a of the cutting blade 16 and the wall surface 19e of the cutting blade 18, and discharges chips cut mainly by the blade surface 17a. 32 is formed by the blade surface 19a of the cutting blade 18 and the wall surface 17e of the cutting blade 16, and discharges chips cut mainly by the blade surface 19a.

  By the way, as described above, in such a drill 10, the strength (rigidity) such as the bending strength of the drill 10 and the shape of chips (depending on the inclination angle of the cutting edge 16 (18) with respect to the axial direction, that is, the so-called twist angle. Size) and its emissions will change. That is, when the twist angle is small, for example, about 0 to 15 ° (hereinafter also referred to as a weak angle), the rigidity is high, but the cutting resistance tends to be large, and the chip is small but the discharge property is small. Lower. On the other hand, when the twist angle is large, for example, about 25 to 45 ° (hereinafter also referred to as a strong angle), the rigidity is low, but the cutting resistance tends to be small, and the chips are large (long). Its emissions are high.

  Therefore, in the drill 10 according to the present embodiment, as shown in FIGS. 2A and 2B, the tip side in which a portion of the distance L1 is formed at a constant first twist angle α1 along the cutting direction from the tip of the blade portion 12. The cutting edges 16a and 18a have a distance L2 on the rear end side with a variable twist angle αx that gradually changes from the first twist angle α1 to the second twist angle α2 (an angle different from the first twist angle α1). The formed intermediate grooves 16b and 18b are configured as rear end side grooves 16c and 18c formed at a constant second twist angle α2 at a distance L3 on the rear end side. As can be seen from FIG. 2A, the rear end side grooves 16 c and 18 c form the rear end of the blade portion 12 that continues to the shank portion 14. Therefore, the cutting edge 16 includes a front end side cutting edge 16a formed with a constant first torsion angle α1, a rear end side groove 16c formed with a constant second torsion angle α2, and a variable connecting them. The intermediate groove 16b is formed with a twist angle αx, and the cutting edge 18 is similarly configured.

  That is, in the drill 10 according to the present embodiment, the first twist angle α1 is a weak angle of about 0 to 15 ° (in the case of the present embodiment), as can be understood from the graph showing the change in the twist angle in FIG. 2B. 10 °), the second twist angle α2 is set to a strong angle of about 25 to 45 ° (35 ° in this embodiment), and the twist angle αx is about 0 to 45 °. The changing angle, that is, a so-called variable angle (10 to 35 ° in the case of the present embodiment) is set. Further, in the drill 10, the distance L1 where the front end side cutting edges 16a and 18a are formed, the distance L2 where the intermediate grooves 16b and 18b are formed, and the distance L3 where the rear end side grooves 16c and 18c are formed are L1. For example, the distance L2 is about 2 to 3 times the distance L1, and the distance L3 is about 15 times the distance L1.

  As shown in FIG. 2A, the branch point 28a of the oil passage 28 is set, for example, in a region of a distance L2 where the intermediate grooves 16b and 18b are formed. Naturally, the branch point 28a can be set in the region of the distance L1 where the front end side cutting edges 16a and 18a are formed or at other positions, and the oil passage 28 is all one or two from the front end to the rear end. It is also possible to form with a book.

  Next, the operation and effect of the drill 10 according to the present embodiment configured basically as described above will be described.

  First, as a workpiece (not shown), for example, a cylinder block made of cast aluminum is disposed on a machine tool (not shown), and the shank portion 14 of the drill 10 is fixed to a rotational drive source of the machine tool via a chuck or the like. Then, the said rotational drive source is started and the drill 10 is rotated at high speed in the arrow A direction of FIG. 3A. Next, when the tip surface 20 of the drill 10 is brought into contact with the deep hole cutting position of the workpiece and is displaced along the axial direction, the blade portion 12 starts cutting the workpiece.

  In the drill 10 according to the present embodiment, the cutting of the deep hole is started by the distal end side cutting edges 16a and 18a formed on the distal end side among the cutting edges 16 and 18 formed on the blade portion 12, and gradually, the intermediate groove Cutting is performed while 16b and 18b and the rear end side grooves 16c and 18c are inserted into the workpiece.

  In this case, in the drill 10, the distal end side cutting edges 16 a and 18 a are set with a weak first twist angle α 1. For this reason, since the leading end side cutting edges 16a and 18a have high rigidity and high cutting ability with respect to the workpiece, even when there is no pilot hole such as a cast hole, the tip side cutting blades 16a and 18a are reliably and stably attached to the workpiece. Can be cut. In addition, chips generated by cutting the front end side cutting edges 16a and 18a are sufficiently small. Therefore, even when the drill 10 gradually reaches the deep part of the hole, chips generated by cutting the front end side cutting edges 16a and 18a increase from the intermediate grooves 16b and 18b to the rear end side grooves 16c and 18c. It is forced out of the hole by the action of the twist angle. This is because, as described above, when the twist angle is large, chip discharge performance is enhanced.

  That is, in the drill 10, the tip-side cutting edges 16 a and 18 a can be made finer by the weak first twist angle α 1, so that the intermediate grooves 16 b and 18 b with the variable twist angle αx and the first angle with a strong angle can be reduced. The chip can be easily and efficiently discharged from the deep part of the deep hole to the outside of the deep hole by a synergistic effect with the high chip discharge property by the rear end side grooves 16c and 18c of the two twist angles α2. . In particular, when a deep hole is made in a workpiece having no prepared hole such as a punched hole, a large amount of chips are generated, so that the drill 10 according to this embodiment can be used more suitably. Moreover, since the chip 10 can improve chip discharge efficiency, it is possible to effectively prevent clogging of chips in the middle of the hole that causes damage to the drill 10. For this reason, it becomes possible to reduce the load to the drill 10 and to maintain a long tool life.

  In this case, in the drill 10 according to the present embodiment, the distance L3 in which the rear end side grooves 16c and 18c are formed is set sufficiently longer than the distance L1 in which the front end cutting edges 16a and 18a are formed. . Thereby, as described above, even when cutting a deep hole where a large amount of chips are generated, the chips can be more reliably transferred in the direction of the rear end side (shank portion 14 side) of the drill 10. It becomes. That is, when cutting a deep hole, most of the cutting is actually performed by only a part on the tip side of the blade portion 12, and therefore when the deep hole is cut, a part on the tip side of the drill 10 is used. This is because, in most cases except for, a high chip discharge property is required to smoothly transfer the chips to the opening side of the deep hole.

  Further, the rear end side grooves 16c and 18c are inserted into the holes after being cut to some extent by the front end side cutting edges 16a and 18a and the intermediate grooves 16b and 18b. Absent. In addition, since the rear end side grooves 16c and 18c are the second twist angle α2 having a strong angle, the chip discharge speed is improved, so that an increase in resistance due to clogging of the chips can be prevented. Further, as described above, the distance L3 in which the rear end side grooves 16c and 18c are formed is sufficiently longer than the distance L1 in which the front end side cutting edges 16a and 18a are formed. It is possible to more reliably prevent an increase in resistance due to.

  Further, the twist angle αx of the intermediate grooves 16b and 18b is gradually increased in a direction that gradually eliminates the angle difference between the first twist angle α1 of the front end side cutting edges 16a and 18a and the second twist angle α2 of the rear end side grooves 16c and 18c. It is set to change (see FIG. 2B). For this reason, it can suppress effectively that the blade part 12 produces an abrupt characteristic change in the axial direction due to the difference in the twist angle, and as a result, the load during cutting of the drill 10 is suppressed, and the tool life of the drill 10 is reduced. It can be further extended.

  In the drill 10, it may be necessary to re-polish the tip end side of the blade portion 12 by cutting a plurality of times or cutting a hard material. In this case, in the drill 10, the distal end side cutting edges 16 a and 18 a constituting the distal end side of the cutting edges 16 and 18 are set to be constant at a weak first twist angle α 1 and a sufficient distance L 1 is set. Therefore, by the re-polishing, it is possible to effectively prevent changes in the characteristics of the front end side cutting edges 16a and 18a, that is, the shape and size of the chips during cutting, and stable cutting characteristics are always obtained. Obtainable.

  Further, in the oil passage 28 in the drill 10, the branch point 28a is set at a portion where the intermediate grooves 16b and 18b are located as described above. That is, in most of the axial direction of the drill 10 from the shank portion 14 to the rear end side grooves 16c and 18c and a part of the intermediate grooves 16b and 18b, the oil passage 28 passes through one axial center position of the drill 10. Has been. For this reason, the flow resistance (passage resistance) of the cutting oil in the oil passage 28 can be lowered, and the twisted shape in the rear end side grooves 16c and 18c having the second twist angle α2 having a strong angle can be achieved. The restrictions concerning formation can be eliminated and a free twist can be set. In addition, since the distal end side cutting edges 16a and 18a have a weak first twist angle α1, the Y shape of the oil passage 28 from the branch point 28a to the distal end side can be easily formed. In addition, since the branch point 28a is set at the portion where the intermediate grooves 16b and 18b are located as described above, the positions of the openings 26a and 26b on the front end side of the oil passage 28 are hardly changed even by the re-polishing. In other words, it is possible to effectively prevent the oil supply characteristics from the openings 26a and 26b from being changed to the cutting portion, thereby enabling more stable cutting.

  Moreover, in the drill 10, a diamond cutting edge can be fixed to the front end side cutting edges 16a and 18a, or a diamond coating can be applied. Thereby, chip discharge | emission property improves further and the abrasion resistance of a blade edge | tip improves.

  As described above, the present invention has been described with the embodiments. However, the present invention is not limited to this, and it is naturally possible to adopt various configurations without departing from the gist of the present invention.

It is a perspective view of a drill concerning one embodiment of the present invention. 2A is a side view of the drill shown in FIG. 1, and FIG. 2B is an explanatory view showing a change in the twist angle of the blade portion of the drill shown in FIG. 3A is a front view of the drill shown in FIG. 2, FIG. 3B is a partially omitted side view in which the tip side of the drill shown in FIG. 2 is enlarged, and FIG. 3C is the tip side of the drill shown in FIG. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Drill 12 ... Blade part 14 ... Shank part 16, 18 ... Cutting blade 16a, 18a ... Front end side cutting blade 16b, 18b ... Intermediate groove 16c, 18c ... Rear end side groove 17a, 19a ... Blade surface 20 ... End surface 26a, 26b ... Opening 28 ... Oil channel 28a ... Branching points 30, 32 ... Chip discharge groove

Claims (3)

A drill comprising a blade portion in which a spiral cutting blade is formed along a cutting direction from the front end side toward the rear end side, and a shank portion formed continuously on the rear end side of the blade portion,
The blade portion is provided along the cutting direction from the tip of the blade portion, and a tip-side cutting blade formed at a constant first twist angle;
An intermediate groove formed along the cutting direction from the tip side cutting edge and formed with a twist angle that gradually changes from the first twist angle to the second twist angle along the cutting direction;
A rear end side groove formed along the cutting direction from the intermediate groove and formed at a constant second twist angle;
Have
The rear end side groove is set to have a longer length in the cutting direction than the front end side cutting edge, and the second twist angle is set to be larger than the first twist angle. Features a drill. The drill according to claim 1, wherein
The drill characterized by the diamond provided in the front-end | tip of the said blade part. The drill according to claim 1, wherein
In the drill, an oil passage penetrating from the front end to the rear end along the axial direction is formed, and the oil passage is formed by one from the shank portion side to the position where the intermediate groove is formed, A drill characterized in that, after branching into two at a position where the intermediate groove is formed, two holes are opened at the tip surface of the blade portion.

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