JPS6393509A - Drill - Google Patents

Abstract

PURPOSE:To prevent a walking phenomenon of a drill tip during cutting, reduce the cutting resistance, and allow accurate boring by forming an auxiliary groove communicated to a chip discharging main groove in the re-grinding range of a web thickness portion. CONSTITUTION:The outside end section 5b of the heel face 5 of a drill 1 is formed thicker than that of a standard drill, on the other hand, its center side is recessed to be thinner than that of a high-rigidity drill and the standard drill. Next, an auxiliary groove 8 is formed in a fixed range 1 along the axial direction from the drill tip side, and this range is made the range where the cutting blade of the drill 1 can re-grind. According to this drill 1, chips generated by the cutting of the drill 1 are guided into a main groove 6 along the curved face of the outside 4a of the triangular protruded section 4c of the blade rear face 4 and discharged satisfactorily. Chips crushed by a chisel edge are guided into the main groove 6 from the auxiliary groove 8 and discharged satisfactorily, the cutting resistance is reduced and the cutting ability is improved, and furthermore the biting property on a material to be cut is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to drills, and more particularly to drills that essentially do not require thinning.

BACKGROUND OF THE INVENTION Conventionally, in drilling holes with a drill, the rigidity of the drill has generally been increased in order to increase efficiency. In other words, this drill 2 with increased rigidity
As shown by the two-dot chain line in FIG. 1, the blade back surface 2b and heel surface 2c are each formed thicker than the standard drill 3, which is shown by the dotted line 3 in the figure, in the cross section of the blade in the direction perpendicular to the drill axis. The core thickness is increased to provide rigidity.

Note that the standard drill 3 mentioned above is, for example, JIS B4
It is a commercially available drill based on the 30I straight shaft drill standard, and its core thickness is generally (0
, 15 to 0.18). However, D is the drill diameter.

The problem to be solved by the invention is, however, with the structure described above, since the core thickness is large, the chisel edge becomes larger than that of the standard drill 3 when the cutting edge is sharpened, and as a result, the cutting resistance becomes thicker ( As a result, machinability deteriorates, and it becomes necessary to accurately perform thinning over a relatively wide area as shown by diagonal lines in Fig. 7.8.9, and there is a problem that the skill of thinning affects the accuracy of drilling. There is also the problem that this thinning must be performed every time re-grinding is performed, which is extremely troublesome.

Therefore, an object of the present invention is to provide a drill that can drill holes with high accuracy without thinning.

Means for Solving the Problems In order to achieve the above object, the present invention is configured such that a sub-groove communicating with the main groove for chip ejection is formed within the re-grinding range of the thick core portion. In other words, for a standard cross-sectional blade shape in which the heel surface and the back surface of the blade that constitute the main groove for chip ejection form a roughly smooth curved surface in the axial cross-section of the drill, the heel surface of the heel surface is smaller than the heel surface of the standard cross-sectional blade shape. After protruding all or part of the outer side portion, i.e., the entire outer edge, cutting off only the heel portion, the remaining portion that is not cut off is placed in the main groove for chip ejection. It protrudes and has a cross-sectional shape within a predetermined range along the axial direction from the tip, with the back surface of the blade protruding in a substantially triangular shape from the back surface of the blade of the standard cross-sectional blade shape toward the main groove for discharging chips. , in the cross-sectional shape within the predetermined range and within the re-grindable range in the axial direction from the tip, a sub-groove recessed in a substantially U-shape from the heel surface of the standard cross-sectional blade shape is formed on the heel surface of the heel surface. The core thickness of the minor groove forming part is (0.04 to 0.11) x the drill diameter, and the core thickness of the part where the minor groove is formed is within the predetermined range and where the minor groove is not formed. The thickness dimension is (0,25 to 0.40) x drill diameter, and the sub-groove is connected to a parallel part extending along the axial direction from the tip and having a constant core thickness dimension, and the parallel part. and an inclined portion having a core thickness taper of 2/100 to 6/+00.

Effect of Hiroaki In the above structure, the chisel edge becomes smaller due to the sub-groove, and during cutting, the tip of the drill does not perform the so-called walking phenomenon against the material to be cut, the center of rotation of the drill does not move, and the cutting resistance is also reduced. , can perform hole drilling with high precision.

EMBODIMENT OF THE INVENTION Below, embodiments according to the present invention will be described in detail based on the drawings shown in FIGS. 1 to 6.

Figures 1.2.3 each show a drill l according to an embodiment of the present invention.
4 is a cross-sectional view of the main part of the blade, FIG. 5 is a sectional view taken along the line ■-■ in FIG. 4, and FIG. The figure is a front view of the tip of a specific drill blade.

In FIG. 1, the dotted line indicates a conventional standard drill 3 having a standard cross-sectional blade shape in which the heel surface 3b and the blade back surface 3a forming the chip ejection groove form a substantially smooth curved surface in the axial cross section of the drill. The two-dot chain line indicates a conventional high-rigidity drill 2 with a large core thickness. In addition, in the figure, 2b is the back surface of the blade, and 2c is the heel surface.

The drill 1 is formed point-symmetrically with respect to the axial center 0 point in FIG. 1 in an axial cross-section of the drill within a predetermined range along the axial direction from the tip, and has a pair of main grooves 6, 6 for discharging chips.
is formed in a spiral along the axial direction, and the groove wall surface of each curved main groove 6 is provided with a blade back surface 4 and a heel surface 5, respectively.

The blade back surface 4 is made thicker than the standard drill 3 by projecting into the main groove 6 in a substantially triangular shape from the standard drill 3 in the axial cross section of the drill to form a protrusion 4c. That is, while the outer side 4a of the blade back surface 4 is made to protrude like the conventional high-rigidity drill 2, the middle 8 side 4b is made to protrude like the conventional high-rigidity drill 2.
Make a depression from the center side to reduce the thickness of the heart.

Further, in the axial cross section of the drill, the heel surface 5 has its outer end 5b protruding into the main groove 6 similarly to the high-rigidity drill 2, as shown by the dashed line in FIG. A U-shaped sub-groove 8 is formed spirally along the axial direction from the outer end 5b toward the center. Therefore, the outer end 5b of the heel surface 5 is made thicker than the standard drill 3, while the center side is recessed to have a smaller core thickness than the high-rigidity drill 2 and the standard drill 3.

Above side 7y! '8 is formed within a certain range C7 along the axial direction from the drill tip side as shown in FIG. 4, and this range is defined as the range in which the cutting edge of the drill 1 can be re-ground. Within the re-grindable range Q where the minor groove 8 is formed, the core thickness dimension W is constant, that is, the parallel core thickness (0 /100), thereby forming a parallel portion 8a whose groove bottom is parallel to the drill axis direction, and forming an inclined portion 8b inclined at a constant angle from the parallel portion within the remaining range L2. Even when re-grinding is performed up to this inclined portion 8b, the size of the chisel edge formed on the tip surface of the blade is smaller than the chisel edge of the standard drill 3, resulting in excellent cutting performance. The drill 1 has a grindstone that forms the sub-groove 8, for example, by grinding off the heel portion 7 as shown by the solid line in FIG. 1 to enlarge the space of the main groove 6 and improve penetration of cutting oil. is preferred. In this case, even if the heel portion 7 was shaved off, the life of the drill did not decrease due to the decrease in the rigidity of the drill.

According to the drill 1, during cutting, chips generated by the cutting of the drill I are guided into the main groove 6 along the curved surface of the outer side 4a of the approximately triangular protrusion 4c on the back surface 4 of the blade, and are efficiently discharged. At the same time, the debris crushed by the chisel edge is guided from the minor groove 8 into the main groove 6 and is efficiently discharged.

FIG. 6 shows a specific example of the drill for steel, which is the drill 1 according to the above embodiment. The core thickness dimension W2 of the main groove part is (0
,25~0°40)D, groove width ratio is 1:l~0.8:I,
The helix angle is 25 degrees, and the core thickness dimension W1 of the minor groove part is (0,0
4 to 0.11)D, and the tip angle is 135 degrees. However, D is the drill diameter. Then, the angle α between the line connecting the outer ends of the double-blade back surface 4.4 and the tangent to the center side curved surface of the blade back surface 4.
is IO° to 15°, the radius of curvature R1 of the curved surface on the center side of the blade back surface 4 is (0,1 to 0.2)D, and the diameter D3 of the curved surface from the blade back surface 4 to the heel surface 5 is φ( 0,1~0
．． 2) Let D be the radius of curvature of the center side curved surface of the heel surface 5.
7 is (0,5~08)D, and the outer end 5 of the heel surface 5
The distance from the center of the drill, that is, the diameter, of the boundary between b and the sub-groove 8 is φ085D. The minor groove 8 has an axial length Q (see Figures 2 and 4), that is, the axial length from the contact point A of the cutting edge and the minor groove 8 is (0.5 to 1.1)D.
shall be. With this axial length, it is possible to re-grind the same number of times as a conventional drill, and the service life is also comparable to that of a conventional drill.

However, in order to extend the service life, the shorter the above length, the better. The core thickness taper of the inclined portion 8b of the side bay 8 in the range from W'' to W'' is 2/100 to 6/100.
The core thickness WI is φ13. In the case of Omm or more, the core thickness taper is set to 4/100.

In addition, in conventional high-rigidity drills for steel, the groove width ratio is 08~
0.9:1, and the core thickness was (0.2 to 0.45)D, so it was necessary to perform thinning. In addition, standard drills for steel have a groove width ratio of 1.3:I-1:1 and a core thickness of (
0.1 to 0.20)D, and thinning was required.

In addition, the flute width ratio and core thickness dimensions of drill 1 are for light alloys,
Unlike the drills for aluminum and the steel drills mentioned above, it is necessary to determine the groove width ratio, core thickness, etc. depending on the respective use so that thinning is not necessary. As a reference example of this drill for light alloys and aluminum, the groove width ratio is increased to 1.5:l-1,6°1, and the helix angle is set to 3.
There is a drill with a larger core thickness of 8 to 42 degrees, but with the same core thickness as a steel drill.

According to the above embodiment, since the heel surface 5 is provided with the sub-groove 8, the core thickness is smaller than that of the standard drill 3 or the high-rigidity drill 2, and as a result, the chisel etching becomes smaller when the cutting edge is raised.
During cutting, the so-called walking phenomenon does not occur, making it possible to drill holes with high precision.The cutting resistance is also reduced, improving machinability, and the ability to bite into the material to be cut is also improved, which eliminates the need for thinning. It disappears. Therefore, it is possible to reliably solve the problem of the conventional high-rigidity drill 2 in which the skill of thinning affects the precision of hole drilling. Further, there is no need to perform thinning every time the drill is re-grinded, and sufficient cutting can be achieved by simply sharpening the cutting edge at the tip of the drill. In addition, since the sub-groove 8 is provided on the center side of the heel surface 5, the groove for discharging chips can be replaced with the conventional high-rigidity drill 2 or standard drill 3.
In addition, the chips can be made larger than the chip ejection grooves 8 and 6 for deposit ejection along the curved surface of the outer side 4a of the protrusion 4C on the back surface 4 of the blade. Improves drainage performance. In addition, since the parallel part 8a is formed in the leg groove 8, the cutting edge can be made rigid, and the core thickness of the parallel part 8a can be measured in the quality inspection process at the manufacturing stage of the drill. By doing so, it is possible to stabilize the quality of the product. In other words, if the sub-groove 8 is constructed from only the inclined part without forming a parallel part, when measuring the core thickness dimension in the sub-groove part, for example, if the position of the measuring tip of the micrometer is slightly deviated, the core thickness dimension will be Because of the different values, it was difficult to measure the same location for each drill l, making it difficult to stabilize the quality of the product. In addition, the outer end 5 of the heel surface 5
By increasing the thickness of b and forming the protruding portion 4c on the back surface 4 of the blade, the drill rigidity can be improved without increasing the core thickness. Furthermore,”−
As described above, in response to the reduced core thickness, the cross-sectional area of the chip ejection groove is larger than that of the standard drill 3 and the high-rigidity drill 2, and the chip ejection performance is improved.

Effects of the Invention According to the above structure, by forming a substantially U-shaped sub-groove on the center side of the heel surface of the blade, the core thickness is reduced and the jelly edge is reduced, thereby preventing the so-called walking phenomenon during cutting. It is possible to effectively prevent the center of rotation of the drill from moving without causing any friction, and the cutting resistance is reduced, cutting performance is improved, and the ability to bite into the material to be cut is also improved. Therefore, there is no need for thinning, and since the skill of thinning does not affect the accuracy of hole drilling, it is possible to drill holes with high accuracy even when thinning is performed. Further, there is no need to perform thinning every time the drill is re-grinded, and sufficient cutting can be achieved simply by sharpening the cutting edge at the tip of the drill.

In addition, since the sub-groove is provided on the center side of the heel surface, the cross-sectional area of the groove for discharging debris is larger than that of a standard drill or a high-rigidity drill, improving chip discharging performance.

In addition, since a parallel portion is formed in the minor groove, it is possible to provide rigidity to the cutting edge, and the core thickness of the parallel portion can be measured during the quality inspection process during the manufacturing stage of the drill to ensure product quality. can be stabilized.

In other words, if a sub-groove is formed only from an inclined part without forming a parallel part, when measuring the core thickness of each drill in the sub-groove part using, for example, a micrometer, the position of the measuring point of the micrometer will be misaligned even a little. Since the core thickness dimension differs depending on the slope of the core thickness part, it is necessary to accurately position the gauge head in the same position on each drill, and it is extremely difficult to position the gauge head in the same position. ,
It was difficult to stabilize the quality of the product. In addition, in the axial cross section of the drill, the outer end of the heel surface of the blade protrudes into the chip ejection groove, while the back surface of the blade protrudes in a substantially triangular shape toward the depth ejection groove, without increasing the core thickness. It is possible to increase the rigidity of the drill and increase the efficiency of hole drilling. Further, since the back surface of the bipedal blade protrudes in a substantially triangular shape, cut chips, that is, chips, are smoothly guided into the chip ejection groove along the outer slope of the substantially triangular protrusion.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the blade of a drill according to an embodiment of the present invention, FIGS. 2 and 3 are a side view and an end view of the drill according to the above embodiment, respectively, and FIG. 1 is a cross-sectional side view of the main part of the drill bit shown in FIG. 1, FIG. 5 is a cross-sectional view taken along the line v-■ in FIG. Figures 1 to 9 are explanatory views of conventional high-rigidity drills after thinning. Trill according to Example, 2 Conventional trill, 2b
Back side, 2c Heel part, j (marked Petrill, 3 a-
Back side of the blade, 3b-1-z-ru side, 4 Back side of the blade, 4a/outside, IE) center side, 4c protrusion, 5 heel part, 8
・Minor groove, 5b Outer end, 6,000・For spit discharge] Collar t
η, 7 Heel part 3, Special application K Co., Ltd., Kobe Steel agent I
Rinih Yamaboshi and 2 others Figure 4 Figure 6 Figure 5 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] (1) Heel surface (3) forming the chip ejection main groove (6)
b) and the back surface of the blade (3a) in the axial cross section of the drill,
For a standard cross-sectional blade shape that has a roughly smooth curved surface, all or part of the outside portion of the heel surface of the heel surface (5) from the heel surface (3b) of the standard cross-sectional blade shape is the main groove for chip ejection (6). ), and the blade back surface (4) of the standard cross-sectional blade shape is more closely aligned with the chip ejection main groove (3a) than the blade back surface (3a).
6) has a substantially triangular cross-sectional shape protruding toward the tip within a predetermined range along the axial direction from the tip, and a re-grindable range within the predetermined range and along the axial direction from the tip ( In the cross-sectional shape in l_2), a sub-groove (8) recessed in a substantially U-shape from the heel surface (3b) of the standard cross-sectional blade shape is provided on the center side of the heel surface of the heel surface (5). When using a drill, the core thickness of the above sub-groove forming part is (0.04 to 0.11).
x drill diameter (D), the core thickness dimension in the part without the above-mentioned minor groove (8) within the above-mentioned predetermined range is (0.25-0.
40)×drill diameter (D), and the sub-groove (8) has a parallel portion (8a) extending along the axial direction from the tip and having a constant core thickness dimension, and a parallel portion (8a) in the parallel portion (8a). Inclined portions (8
b) A drill characterized by comprising: