JP2009018384A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill capable of maintaining a long life of a tool for a long period of time by reducing a load applied on the drill even if drilling a cast hole, and improving drilling accuracy. <P>SOLUTION: The drill 10 is provided with a blade 12 having cutting edges 17a, 19a at the tip of the drill, and a shank 14 formed at the tail side of the edge 12. Lands 17b, 19b continued from the cutting edges 17a, 19a; clearances 17c, 19c continued from the lands 17b, 19b and having small diameters in the radial direction from the lands 17b, 19b; and pads 17d, 19d continued from the clearances 17c, 19c and having larger diameters in the radial direction from the rib clearances 17c, 19c are arranged on the edge 12 in a front view to the drill 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  As a drill for drilling holes in metal parts such as engine parts, the present applicant proposes a technical idea of forming a bulging portion in a chip discharge groove formed between a plurality of cutting blades in Patent Document 1. is doing. Thereby, it is possible to improve the rigidity of the drill and improve the chip discharging property.

  FIG. 5 is a schematic side view of a drill 100 according to this type of prior art, and FIG. 6 is a schematic front view of the drill 100 shown in FIG. Show. As shown in FIGS. 5 and 6, the drill 100 is formed with a pair of two cutting blade portions 106 and 108 that are arranged symmetrically with respect to the apex (chisel point) 104 that is the foremost end of the blade portion 102. ing.

  In such a drill 100, one cutting edge portion 106 includes a cutting edge 107a located on the front side in the rotation direction of the drill 100 (the direction of arrow A in FIG. 6), and a land portion 107b continuous from the cutting edge 107a. The arc portion 107c is continuous with the land portion 107b and has a smaller diameter in the diameter direction than the land portion 107b. That is, the land portion 107b constitutes the outer diameter surface of the drill 100 (blade portion 102). Similarly, the other cutting edge portion 108 includes a cutting edge 109a, a land portion 109b, and an arc portion 109c.

Registered Utility Model No. 25333255

  By the way, for example, in the case of continuously producing engine parts made of aluminum casting, holes formed by casting in the engine parts, so-called cast holes, may vary in formation positions depending on the casting accuracy. is there. For this reason, when such a hole is cut with a drill, a displacement occurs between the cutting direction (cutting position) of the drill and the hole, resulting in a large load on the drill, There is a possibility that the service life and machining accuracy may be reduced.

  In this case, it is naturally possible to use the drill 100 according to the conventional configuration for cutting the punched hole. However, normally, in such a drill 100, the width in the rotation direction of the land portion 107b (109b), that is, the so-called margin width W is set to be relatively large with respect to the diameter of the drill 100 in the front view shown in FIG. Therefore, in particular, when the displacement occurs, the resistance (reaction force) due to the side wall of the hole tends to increase. Furthermore, in the drill 100, the angle θ of the cone-shaped tip surface with the vertex 104 as the center is slightly smaller in the side view shown in FIG. 5, and is set to about 118 ° to 135 °, for example. The cutting reaction force (radial reaction force) tends to increase. As a result, when cutting the core hole, it is difficult to make the drill 100 travel straight in the axial direction, which may cause a reduction in processing accuracy and damage to the drill itself.

  In other words, a drill used for machining such a punched hole can maintain its cutting direction without being affected by the above-described positional deviation, causing deformation of the drill itself and a reduction in machining accuracy. It is hoped not to.

  The present invention has been made in connection with the above-described conventional technology. For example, even when cutting a punched hole, the load applied to the drill can be reduced and the tool life can be maintained long. An object of the present invention is to provide a drill capable of improving machining accuracy.

  A drill according to the present invention is a drill including a blade portion having a cutting edge formed at a tip thereof and a shank portion continuously formed on a rear end side of the blade portion, In a front view with respect to the drill, a land portion continuous from the cutting edge, a relief portion continuous from the land portion and having a smaller diameter in the diameter direction than the land portion, and continuous from the relief portion and diameter direction from the relief portion And a large-diameter pad portion.

  According to such a configuration, by providing the pad portion continuous from the escape portion, the resistance due to the sidewall of the hole can be released at the escape portion, and the pad portion is connected to the land portion by the second portion. It can function as a land part. Therefore, for example, at the start of cutting into a core hole, the drill can be stably placed along the side wall of the core hole, and the straight running stability can be greatly improved. For this reason, according to the drill according to the present invention, even if a positional deviation occurs between the axial direction of the core hole and the axial direction of the core hole, the position of the core hole is almost affected. Therefore, it is possible to cut straight along the axial direction, and it is possible to reliably perform drilling at a desired position with high accuracy. In addition, it is possible to effectively prevent the drill from being inserted into the casting hole in an oblique direction due to the displacement and causing bending, breakage, and the like, so that the tool life can be maintained long.

  Further, when the pad portion has a diameter smaller than that of the land portion in a front view with respect to the drill, the pad portion protrudes in the outer diameter direction of the drill from the land portion, and the pad portion is a workpiece. It is possible to avoid the occurrence of cutting defects and the like.

  Furthermore, if the pad portion is larger than the land portion in the rotational direction of the drill, for example, when cutting a cast hole, the width of the land portion is small, so the resistance due to the side wall of the cast hole is effective. In addition, since the pad portion has a predetermined width, the pad portion can be surely aligned with the side wall of the hole, so that the straight running stability can be further improved. It becomes possible.

  Furthermore, when the angle of the tip of the blade is 160 ° or more in a side view with respect to the drill, the cutting reaction force in the rotation direction can be effectively reduced, and the straightness at the time of cutting is further improved. It becomes possible to improve.

  According to the present invention, by providing the relief portion and the pad portion continuously from the land portion continuous from the cutting edge, the resistance due to the side wall of the hole can be released at the relief portion, and the pad portion is It can function as a second land portion following the land portion. Therefore, it becomes possible to make the said drill follow along the side wall of a hole stably, and the straight running stability can be improved significantly. For this reason, in particular, it becomes possible to cut straight along the axial direction at the start of cutting, and it is possible to perform drilling at a desired position reliably and accurately. In addition, since it is possible to effectively avoid the bending of the drill in the oblique direction due to the positional deviation and the occurrence of bending or breakage, it is possible to maintain a long tool life.

  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 schematic side view of a drill 10 according to an embodiment of the present invention. 2 is a schematic front view of the drill 10 shown in FIG. 1, showing a tip surface of the blade portion 12 constituting the drill 10, and FIG. 3 is a schematic cross-sectional view taken along the line IIB-IIB in FIG. It is. The drill 10 according to the present embodiment can be suitably used, for example, when cutting a punched hole previously formed in a cast part as a work, and the work is a cylinder block that is an engine part made of aluminum casting. Etc. are exemplified. Needless to say, the drill 10 can be used effectively other than such a punched hole, for example, when drilling a metal part from scratch.

  As shown in FIG. 1, a drill 10 according to this 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. 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.

  The blade portion 12 is formed with a pair of cutting blade portions 16 and 18 in a spiral shape 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 to 3, the cutting blade portions 16 and 18 extend 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.

  One cutting edge portion 16 is continuous from the cutting edge (blade surface) 17a located on the front side in the rotation direction of the drill 10 (the direction of arrow A in FIG. 2), and the outer diameter surface of the drill 10. A land portion (margin portion) 17b, a relief portion 17c continuous from the land portion 17b and having a smaller diameter in the diameter direction of the drill 10 than the land portion 17b, and a relief portion 17c continuous from the relief portion 17c. A pad portion 17d having a diameter larger than that of the portion 17c, an arc portion 17e which is continuous from the pad portion 17d and has substantially the same diameter in the diameter direction, and the other cut portion from the arc portion 17e. It is comprised from the wall surface 17f connected to the cutting blade (blade surface) 19a of the blade part 18. As shown in FIG. Similarly, the other cutting edge part 18 is comprised by the cutting edge 19a, the land part (margin part) 19b, the escape part 19c, the pad part 19d, the circular arc part 19e, and the wall surface 19f. In this case, as shown in FIG. 2, the center of the pad portion 17d (19d) is a predetermined angle θ1 (for example, 35 ° to 55 ° from the land portion 17b (19b). In this embodiment, 45 ° ) It is placed at a shifted position. Further, the pad portion 17d (19d) is set to have the same diameter or less in the diameter direction as compared with the land portion 17b (19b). This is because if the pad portion 17d (19d) protrudes more in the outer diameter direction of the drill 10 than the land portion 17b (19b), the pad portion 17d (19d) collides with the workpiece and causes cutting failure or the like.

  The tip surface 20 of the blade portion 12 has a conical shape centering on a cutting edge ridge (chisel edge) 20b including a vertex (chisel point) 20a which is the most distal end of the drill 10 (see FIGS. 1 and 2). In the side view shown in FIG. 1, it has a fan shape having a predetermined angle θ2 (in the present embodiment, 166 °) centered on the vertex 20a. Thus, when the angle θ2 is an obtuse angle, the cutting reaction force (radial reaction force) in the rotation direction of the drill 10 can be reduced. Therefore, the angle θ2 is preferably set to 160 ° or more, for example. .

  As can be understood from FIG. 2, the tip surface 20 has a first tip inclined surface 22 a, a second tip inclined surface 22 b, and a third tip that are inclined from the apex 20 a (the cutting edge ridge 20 b) toward the one cutting edge 16. By forming the inclined surface 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 portion 18, it is formed in the above-mentioned cone shape. Has been.

  Further, in the blade portion 12, between the cutting blade portions 16 and 18 extending spirally as described above, the chips of the workpiece cut by the cutting blades 17a and 19a of these cutting blade portions 16 and 18 are, Chip discharge grooves 30 and 32 for transferring to the shank portion 14 side, which is the rear end side of the blade portion 12, are formed. That is, as shown in FIG. 2, the chip discharge groove 30 is formed by the cutting edge 17 a of the cutting edge portion 16 and the wall surface 19 f of the cutting edge portion 18, and mainly discharges the chips cut by the cutting edge 17 a. The discharge groove 32 is formed by the cutting edge 19a of the cutting edge portion 18 and the wall surface 17f of the cutting edge portion 16, and discharges chips cut mainly by the cutting edge 19a.

  By the way, in the drill 100 according to the conventional configuration described above, the width of the land portion 107b (109b), that is, the so-called margin width W is set to be relatively large (see FIG. 6). % Is set. Furthermore, the angle θ around the apex 104 of the tip surface is slightly small, for example, set to about 118 ° to 135 °. For this reason, in particular, when cutting a punched hole, it is difficult to maintain the cutting direction, which may cause a reduction in processing accuracy and damage to the drill itself.

  Therefore, in the drill 10 according to the present embodiment, the margin width W1 which is the width in the rotation direction of the land portion 17b (19b) is minimized (minimized) in the front view shown in FIG. 1 is set to about 3% or less of the diameter, and in the side view shown in FIG. 1, the angle θ2 with respect to the apex 20a of the tip surface 20 is set to 160 ° or more to improve the processing accuracy and tool life. ing. The relationship between the margin width W1 of the land portion 17b (19b) and the width W3 of the pad portion 17d (19d) is, for example, that the sum of the margin width W1 and the width W3 is 20% of the diameter of the drill 10. It is set to be about the following. That is, the width W3 of the pad portion 17d (19d) is set larger than the margin width W1 of the land portion 17b (19b).

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

  First, as shown in FIG. 4, a cylinder block made of, for example, aluminum casting is arranged as a work 41 on a machine tool (not shown), and the shank of the drill 10 is connected to the rotational drive source 40 of the machine tool via a chuck. The part 14 is fixed. Thereafter, the rotational drive source 40 is started to rotate the drill 10 at a high speed in the direction of arrow A in FIG. Next, the cutting of the workpiece 41 is started by displacing the tip surface 20 of the drill 10 along the axial direction thereof toward the cast hole 42 formed in the workpiece 41. That is, cutting into the cast hole 42 is started by the cutting blade portions 16 and 18 formed in the blade portion 12, and the blade portion 12 gradually becomes a hole having a predetermined diameter centered on the cast hole 42 from the tip side. Is inserted into the work 41 while cutting.

  In this case, in the drill 10 according to this embodiment, the margin width W1 of the land portions 17b and 19b constituting the cutting edge portions 16 and 18 is set to be extremely small as compared with the drill 100 according to the conventional configuration. The resistance (reaction force) due to the side wall of the core hole 42 can be effectively reduced, and the inclination of the drill 10 at the time of cutting can be suppressed. In addition, the drill 10 is provided with pad portions 17d and 19d with the escape portions 17c and 19c sandwiched from the land portions 17b and 19b. That is, the pad portions 17d and 19d function as a second land portion following the land portions 17b and 19b. For this reason, it becomes possible to make the drill 10 follow at least four places (land portions 17b and 19b, pad portions 17d and 19d) with respect to the side wall of the core hole 42, and in particular straightness at the start of cutting (straight running stability) Property) can be greatly improved.

  That is, as shown in FIG. 6, in the drill 100 according to the conventional configuration, since the margin width W of the land portion 107b (109b) is large, the resistance due to the side wall of the hole tends to increase. In such a drill 10, since the margin width W1 of the land portions 17b and 19b continuing from the cutting edges 17a and 19a is set to be extremely small, resistance due to the side wall of the hole can be released by the escape portions 17c and 19c. Moreover, in the drill 10, by providing the pad portions 17d and 19d that are continuous from the relief portions 17c and 19c, the cutting direction is kept almost straight, especially at the start of cutting, and the cutting direction is kept straight. It becomes possible to perform processing. At this time, as described above, since the width W3 of the pad portion 17d (19d) is set larger than the margin width W1 of the land portion 17b (19b), the land portion 17b (19b) having a small margin width W1 is set. Thus, while effectively reducing the resistance (reaction force) due to the side wall of the cast hole 42, the pad 10d having a predetermined width W3 can be used to reliably place the drill 10 along the side wall of the cast hole 42. Further, it is possible to further improve the straight running stability at the start of cutting and at the time of cutting.

  Furthermore, in the drill 10, since the angle θ2 of the tip surface 20 is set to an obtuse angle of 160 ° or more, the cutting reaction force (radial reaction force) in the rotation direction can be effectively reduced, and at the time of cutting It is possible to improve the straightness in the cutting direction, so-called centering property. As a result, the drill 10 can be more reliably and stably cut into the core hole 42.

  Therefore, as shown in FIG. 4, even if there is a positional deviation G between the axial direction D of the drill 10 and the axial direction H of the core hole 42 within a predetermined allowable range, the drill 10 can be cut straight along the axial direction D with little influence on the position of the core hole 42. For this reason, even if the casting accuracy of the cast hole 42 is low, the hole 42a (see the two-dot chain line in FIG. 4) can be reliably drilled at a desired position and has high processing (position) accuracy. ) Can be cut. In other words, the inter-axis distance, which is an error between the processed hole 42a and the desired processing position, can be reliably kept within a predetermined standard value. Furthermore, since the drill 10 can be effectively prevented from being inserted into the casting hole 42 in an oblique direction due to the above-described misalignment G and causing bending or breakage, the tool life can be maintained long. It becomes possible.

  On the other hand, in the above-described conventional configuration, as shown in FIG. 7, when the positional deviation G occurs, the drill 100 obliquely follows the core hole 42 by cutting resistance or the like with respect to the core hole 42. Tilt. Accordingly, the positional deviation G between the axial direction D of the drill 100 and the axial direction H of the punched hole 42 is enlarged, resulting in a more eccentric positional deviation G1, and the hole 42b after the cutting (two-dot chain line in FIG. 7). Reference) is also inclined and low accuracy. Moreover, since the drill 100 is inclined during cutting, the drill 100 may be damaged or deformed.

  In the drill 10 according to the present embodiment, the width of the land portions 17b and 19b is set to a margin width W2 smaller than the margin width W1 at the front end portion at a position spaced from the front end of the blade portion 12 to the rear end side. (See FIG. 3). This is because the rear end side of the blade portion 12 hardly contributes to the cutting, and in particular, it is less necessary to provide the land portions 17b and 19b to improve the straightness thereof. It is also possible to obtain the effect of preventing the damage. Accordingly, the land portions 17b and 19b can be eliminated in the vicinity of the shank portion 14, while the margin widths W1 and W2 can naturally be set to be the same.

  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 schematic side view of the drill which concerns on one Embodiment of this invention. It is a schematic front view of the drill shown in FIG. It is a schematic sectional drawing in alignment with the IIB-IIB line | wire of FIG. It is explanatory drawing which shows the state which cuts into the punching hole of a workpiece | work with the drill shown in FIG. It is a schematic side view of the drill which concerns on a prior art. It is a schematic front view of the drill shown in FIG. It is explanatory drawing which shows the state which cuts into the punching hole of a workpiece | work with the drill shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 ... Drill 12, 102 ... Blade part 14 ... Shank part 16, 18, 106, 108 ... Cutting blade part 17a, 19a, 107a, 109a ... Cutting blade 17b, 19b, 107b, 109b ... Land part 17c, 19c ... Escape part 17d, 19d ... pad part 20 ... tip end face 30, 32 ... chip discharge groove

Claims (4)

A drill comprising a blade portion having a cutting edge formed at the tip and a shank portion formed continuously on the rear end side of the blade portion,
In the front view of the drill, the blade portion has a land portion continuous from the cutting blade, a relief portion that is continuous from the land portion and smaller in diameter than the land portion, and is continuous from the relief portion. A drill having a pad portion having a diameter larger than that of the escape portion in a diameter direction. The drill according to claim 1, wherein
The drill characterized by the said pad part being the same diameter or less in the diameter direction compared with the said land part by the front view with respect to the said drill. The drill according to claim 1 or 2,
The width of the drill in the rotation direction is such that the pad portion is larger than the land portion. In the drill according to claims 1 to 3,
The drill characterized by the angle of the front-end | tip part of the said blade part being 160 degrees or more by the side view with respect to the said drill.

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