JPS60114407A - Drill - Google Patents

Abstract

PURPOSE:To improve strength, cutting resistance and wear-tightness by specifying the relative distance among a radial direction rake angle, a cutting edge and a groove wall in a direct view shape of thickness of core, groove width ratio and cutting edge tip and by coating the cutting edge with a specific material layer in a drill made of super hard material for drilling on such as cast iron. CONSTITUTION:The thickness of a core C is made 25-35% of the drill diameter and the groove width ratio B/A is made 4-8/10, and a cutting edge end face direct view shape on the outer circumference which is 2/3 out of the drill diameter is connected by a straight line or concave curve so that a rake angle in the radial direction becomes -5 deg.C to plus. And the cutting edge of 2/3 out of the drill diameter is made a standard in the cutting edge tip direct view shape and when a vertical line is risen on the datum line from the outer circumference of the groove wall, the distance l2 between the vertical line and the outer circumference of the cutting edge is made 47% or less of the drill diameter D. And all or a portion of the cutting edge 1 is coated with a thin film of TiC, TiCN, Al2O3 etc. Then strength, cutting resistance and wear-tightness of the drill can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a drill used for drilling holes in cast iron or steel materials, and particularly to a cemented carbide drill using cemented carbide as a material.

(b) Conventional technology and its problems Traditionally, high-speed steel drills have been used for drilling in general steel materials and cast iron. Increasingly, the number of rotational speeds is increased to meet these demands, and along with this, cemented carbide, which has excellent wear resistance, is increasingly being used as drill material. However, cemented carbide is not a material with satisfactory strength, such as inferior transverse rupture strength compared to high-speed steel, so its uses are limited, and its cutting resistance and wear are not necessarily sufficient. c) Means, examples, and effects for solving the problem.

The present invention attempts to solve the above problems. That is, the strength of a drill depends on its torsional rigidity and bending rigidity, but the factors that determine this strength are the core thickness and the groove width ratio. Figure 1 shows the torsional rigidity values when the values were changed.

The torsional stiffness ratio is expressed as a ratio of the circular cross section without grooves as 100%. As is clear from FIG. 1, the strength is improved when the core thickness is increased and the groove width ratio is decreased. However, simply increasing the core thickness and decreasing the flute width ratio with the conventional drill shape shown in Figure 2 not only greatly increases cutting resistance (torque, thrust), but also makes it difficult to eject chips. There is a limit to the groove width ratio, and generally the core thickness is set to 15 to 23% of the drill diameter and the groove width ratio is set to 1 to 1.3:1. In FIG. 2, B:A is the groove width ratio, and C is the core thickness. One of the reasons for the increase in cutting force is the second
This is because the rake angle θ in the radial direction is negative at any point in the radial direction of the cutting edge 1 shown in the figure. Also, the relative distance 13 between the groove wall and the opposite groove wall at a negative position
Ii (indicated by A in Fig. 2) naturally becomes larger, and as shown in Fig. 3, the ejected chips 2 may not completely hit the groove wall, and may also cause damage to the machined hole wall. It may extend. 3 indicates the chip contact area.

The present invention has been made to solve such problems. That is, in a drill made of ultra-hard material, the core thickness should be 25 to 35% of the drill diameter, the groove width ratio should be 0.4 to 0.8:1, and the cutting edge should be at least 2/3 of the drill diameter at the outer periphery. @ Directly viewed shape is connected with a straight line or concave curve so that the rake angle in the radial direction is -5° to positive. Assuming that a perpendicular line is drawn from the outer periphery of the groove blade to the M directrix using the cutting edge outside 2/3 as the reference line, the distance 3- between the perpendicular line and the outer periphery of the cutting edge should be 47% or less of the drill diameter. The first feature is that it is close to . The second feature is that at least 2/3 of the diameter of the drill is connected with a concave curve so that the rake angle of the outer circumference when viewed directly from the incisal end is -5° to positive. It is characterized by being partially or entirely covered with a thin film.

Additionally, a margin of the outer diameter portion is provided at the cutting edge position, and is also provided on the opposite side of the cutting edge.

If the core thickness is less than 25% of the drill diameter, torsional rigidity will be insufficient, and if it exceeds 35%, chip evacuation will be poor. Further, if the groove width ratio is outside the range of 0.4 to 0.8:1, the curling and breaking of chips will not work properly. Furthermore, when the rake angle is 15'' or less, the cutting resistance becomes high, indicating insufficient rigidity.

A range of -5° to positive is suitable, but preferably O
By setting the angle in the range of ~20°, the sharpness becomes even better.

Figures 9 and 10 show the effect of the coating layer in the present invention. In a drill having the shape of the present invention with a drill diameter of 12 mm, the cutting edge was coated and the cutting edge was coated and the tip end face was polished. This is a comparative diagram of the results of drilling holes in S 48 CH5220 material at V = 50 m/min using three types: one with no side coating layer, and one with no coating layer at all. As can be understood from the figure, those provided with a coating layer have less cutting force and less wear. The coating layer is formed into a dense thin layer by ion plating or chemical vapor deposition.

Figure 11 is a diagram comparing the sharpness achieved by making the rake angle positive in the radial direction and the flow of chips produced by reducing the relative distance between the cutting edge and the facing groove wall.
At , the chips 11 are bent into small pieces and do not hit the hole wall 12 and do not damage the hole wall, but as the distance from B and C increases, they become larger and hit the hole wall and are cut into large pieces again, so they are ejected. It's not smooth either. Further, the tip angle of a conventional drill is generally 118 to 130 degrees, and in this case, the rake angle is negative. In the present invention, the tip angle is 1
The rake angle is -5° to positive at 35° to 145°. The more positive the torque reduction effect is, but if it is too large, the strength of the cutting edge will decrease.

Therefore, from the viewpoint of both sharpness and strong electric current, a range of 0 to 20° is preferable.

If the core thickness is approximately 30%, the length of the cutting edge C will be +10" (as shown in Figure 12). Therefore, if the cutting edge C has a positive rake angle, it is sufficient. In order to achieve this effect, the above-mentioned condition of at least the outer side of the drill diameter was set.In order to clearly compare the shapes of the present invention and the conventional drill, Fig. 13 and Table 1 are shown. .

Table 1 With the above configuration, the following effects can be obtained.

(1) As shown in FIG. 1, torsional rigidity is greatly improved. The same applies to bending rigidity.

(2) Figure 6 shows an example in which the work material is 550C, H6240, the cutting speed is 50 m/n+in, and a φ8.5 drill is used. This is a significant decrease compared to a conventional drill with a negative radial angle, which has a large core thickness and a large groove width ratio.

(3) By shortening the relative distance between the cutting edge and the groove wall at the outer periphery of the drill, chips can be cut and discharged only within the drill slot, improving the discharge performance. The embodiments shown in Figs. 4 and 5 are cases in which the rake angle in the radial direction is Oa, but Fig. 7 shows an example in which θ has a positive rake angle, contrary to the conventional drill. There is. The effect further enhances the above-mentioned effect. Further, FIG. 8 shows a cutting edge formed in a concave curved shape with an angle of 15° to positive at the outer circumference of the drill. In this case, the generation of chips is shared by the longer cutting edge, so it is done more smoothly, and since the cutting edge length is longer, the amount of work per unit length of the cutting edge is reduced, making it possible to improve wear resistance. Become.

Furthermore, Fig. 7 shows an embodiment with a double margin, that is, a margin section 4.5, which not only improves hole accuracy but also prevents chips from flowing into the second outer circumference. , cutting can be done smoothly.

However, these effects are achieved when the cutting edge is TLCN or TLC.

By being coated with a thin film such as A920J,
It is more effective and the advantages of super hard alloys are fully utilized.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between core thickness and groove center ratio with respect to torsional rigidity. FIG. 2 is a cross-sectional view of a conventional drill, and FIG. 3 shows the movement of chips in the conventional drill. 4 and 5 show a cross-sectional view and a side view of a drill obtained according to the invention. FIG. 6 is a diagram showing the relationship between thrust, torque, and feed in drills of various shapes. 7th
8 are cross-sectional views of other embodiments of the present invention. In the figure, 1 indicates a cutting edge, and 2 indicates a chip. i, 9- indicates the relative distance between the cutting edge and the opposing groove wall. Figures 9 and 10
Figure 11 is a comparison diagram showing the influence of the coating layer, Figure 11 is a comparison diagram showing the flow of chips, Figure 12 is an explanatory diagram showing the drill diameter and cutting edge length, and Figure 13 is a diagram showing the difference between the present invention and the conventional type. It is an explanatory view showing comparison of drills. uJ'-6) I to'Hf @γt, 1- 蓓1+ 1
1 U.S. 9q Procedure Neho (self-motivated) February 19, 1985 Drill name (213>Sumitomo Electric Industries Co., Ltd. specification and drawings 6, contents of amendment Contents of amendment 1 as attached, full text of specification Correct as shown in the attached sheet. 2. Delete drawing No. 9. 3. Correct drawings No. 10 and 13 as shown on the attached sheet. 4. Change the drawing number "Fig. 1" in the drawing. "Fig. 2", "Fig. 2" into "Fig. 1", "Fig. 6" into "Fig. 11", "Fig. 7" into "Fig. 6", "Fig. 8"" to I-Figure 7,""Figure11" to "Figure 8," and "Figure 12" to "Figure 9." 5. Figure 12 of the drawing is revised to the attached sheet. Description 1, Name of the Invention Drill 2, Claims (1) A drill made of ultra-hard material, with a core thickness of 25 to 35% of the drill diameter and a groove width ratio of 0.4 to 0.4. 0.8:1, the radial rake angle of the shape viewed directly from the cutting edge is at least 15° to positive outside 2/3 of the drill diameter, and the radial rake angle of the shape viewed directly from the cutting edge is at least 2/3 Assuming that a perpendicular line is drawn from the outer periphery of the full wall to the reference line using the cutting edge outside of 3 as a reference line, the distance between the perpendicular line and the outer periphery of the cutting blade is 47% or less of the drill diameter, and Part or all of the blade part is TLN, Tic, TLCN or A&2
A drill characterized in that it is coated with one or more of the following: 03 directly or through another layer. (2) The rake angle in the radial direction of the cutting edge portion outside at least 2/3 of the drill diameter is −0 when viewed directly from the cutting edge end face of the portion from the core thickness to the outer periphery of the drill. The drill according to claim 1, characterized in that the drill bits are connected by concave curves so that the curves are positive. (3) The drill according to claim 1 or 2, characterized in that a margin of the outer diameter portion is provided at the cutting edge position and also provided on the opposite side of the cutting edge. (4) A portion of the coated cutting edge includes at least the rake face,
The drill according to claim 1, 2 or 3, which is a margin. 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a drill used for drilling holes in cast iron or steel materials, and particularly to a cemented carbide drill using cemented carbide as the material. <Conventional technology and its problems> High-speed steel drills have traditionally been used for drilling work in general steel materials, cast iron, etc., but recently there has been a strong demand for higher efficiency in drilling work, and drills have become more popular. Increasingly, the number of rotations is increased to meet these demands, and as a result, cemented carbide, which has excellent wear resistance, is increasingly being used as drill material. However, since cemented carbide is not a material with satisfactory strength, such as inferior transverse rupture strength compared to high-speed steel, its applications are limited, and it has not necessarily been sufficient in terms of cutting resistance and wear. The strength of a drill depends on the torsional rigidity and bending rigidity of the material, but the factors that determine the strength are the core thickness C and the groove width ratio B:A shown in FIG. Figure 2 shows the torsional rigidity values when the values were changed. The torsional stiffness ratio is expressed as a ratio with the circular cross section without grooves being taken as 100%. As is clear from FIG. 2, the strength is improved by increasing the core thickness C and decreasing the groove width ratio B:A. However, with the conventional drill shape shown in Fig. 1, simply increasing the core thickness C and decreasing the flute width ratio B:A not only greatly increases the cutting force (torque, to the thrust 1) but also reduces the amount of chips. Ejection is also difficult, and there are limits to the core thickness and groove width ratio; generally, the core thickness is 15 to 23% of the drill diameter, and the groove width ratio is 1 to 1.3:1. Further, one of the reasons for the increase in cutting resistance is that the rake angle θ1 in the radial direction is negative at any position or point in the radial direction of the cutting edge 1 shown in FIG. In addition, the relative distance between the negative position and the opposing groove wall (indicated by 9.1 in Fig. 1) naturally increases, and as shown in Fig. 3, the ejected chips 2 This may occur even if the hole does not hit the complete groove wall, and may reach the machined hole wall. In the figure, numeral 3 indicates the contact portion of the chips 2. Means for Solving the Problems> The present invention has been made to solve these problems, and in a drill made of ultra-hard material, the core thickness C is 25 to 35% of the drill diameter, and the groove width ratio B: A is set to 0.4 to 0.8:1, and the shape of the cutting edge when viewed directly from the outer circumference of at least 2/3 of the drill diameter is such that the rake angle in the radial direction is -5° to positive. The relative distance between the cutting edge 1 and the opposing groove wall,
That is, the shape of the cutting edge when viewed directly [Here, assuming that the cutting edge outside at least 2/3 of the drill diameter is set as a reference line and a perpendicular line is drawn from the outer periphery of the groove wall to the reference line, the - 3- The first feature is that the distance between the perpendicular line and the outer periphery of the cutting edge is close to 47% or less of the drill diameter. The second feature is that at least 2/3 of the drill diameter is connected with a concave curve so that the rake angle of the cutting edge face directly viewed from the outer periphery is positive. It is characterized in that part or all of the blade part is coated with a thin film. Additionally, a margin of the outer diameter portion is provided at the cutting edge position, and is also provided on the opposite side of the cutting edge. <Example and its effects> Made of ultra-hard material, the core thickness C is 25 to 25 mm of the drill diameter.
35%, and the flute width ratio BAA is 0.4 to 0.8:1, and the above rake angle is a rake angle in the radial direction that is at least 2/3 of the diameter of the drill cutting edge when viewed directly from the outer circumference. Ga-
The cutting edge is connected by a straight line or a concave curve so that the angle is 5° to positive, and the relative distance between the cutting edge 1 and the opposing groove wall, i.e., the cutting edge is outside at least 2/3 of the drill diameter when viewed directly from the tip of the cutting edge. Using this as a reference line, draw a perpendicular line from the outer periphery of the groove wall to the reference line.
4- Assuming that it is, the distance between the perpendicular line and the outer circumference of the cutting edge is
Close to 47% or less of the drill diameter, and cover all or part of the cutting edge with a thin film of TLCN, TLc, Al2O3, etc. In the embodiment shown in FIGS. 4 and 5, the rake angle in the radial direction is Oo, and in FIG. 6, the rake angle is a positive angle θ2, contrary to the conventional drill. FIG. 7 shows an example in which the cutting edge 1 is formed in a concave curved shape with an angle of −5° to positive at the outer circumference of the drill. Further, as shown in FIG. 6, margins on the outer diameter portion are also provided at the cutting edge position 4 and at the opposite side 5 of the cutting edge. Each of the above requirements is hindered by the following reasons. Figure 8 shows the sharpness achieved by making the radial rake angle positive and the relative distance between the cutting edge and the groove wall facing the cutting edge.
This figure compares the flow of chips due to the hole wall. In the same figure, when the above relative distance is small, the chips 11 are bent small and do not hit the hole wall] 2 and do not damage the hole wall. As the distance between B and C increases, the bending of the chips increases, and the chips hit the hole wall and are cut into large pieces, making it difficult to eject them smoothly. Further, the tip angle of a conventional drill is generally 118 to 130 degrees, and in this case, the rake angle is negative. In the present invention, the tip angle is 135 to 145 degrees, and the rake angle is 15 degrees to positive. The more exactly the angle is large, the greater the torque reduction effect is, but if it is too large, the strength of the cutting edge is reduced. Therefore, from the viewpoint of both sharpness and strength, O to 20' is preferable. Figure 10 shows examples a' and b of conventional drills A shown in Table 1 below.
', C', d and examples a-f of drill B according to the present invention are illustrated, where C is the core thickness expressed as a percentage of the drill diameter, θ is the rake angle, and R is the groove width ratio. It is clear that in the conventional technology, the rake angle is one angle, and the groove width ratio and core thickness are all different. Table 1 Also, if the rake angle is less than 15°, the cutting force will be high and the rigidity will be insufficient.
It is desirable to have a range of ' from the viewpoint of both sharpness and strength. If the core thickness is 30%, the length of the cutting edge will be 1/3+1/3=2/3 as shown in FIG. Therefore, if 1/2 or more of the cutting edge has a positive rake angle, a sufficient effect will be exhibited, so an extra margin of at least 2/3 of the drill diameter was provided. Furthermore, if the core thickness C is less than 25% of the drill diameter, the torsional rigidity will be insufficient, and if it exceeds 35%, chip evacuation will be poor. If the groove width ratio is outside the range of 0.4 to o, a:1, the curling and cutting of chips will not be successful. In Figure 11, the work material is 550C, HB240, and the cutting speed is 5.
This is a comparison diagram of the characteristics of a drill of the present invention with a diameter of 8.5 mm at 0 m/min and a conventional drill.The drill of the present invention has torque and thrust similar to the conventional drill, and has a negative rake angle in the radial direction Compared to a conventional drill with a large core thickness hole and groove width ratio, this shows a significant decrease. 12 and 13 of the attached drawings are curves showing the effect of the coating layer in the present invention. In a drill with a drill diameter of 12 shoes, after coating the cutting part and re-polishing, the four sides of the tip are coated. 548C1HB220 material with V=50m/mi by three types: one without a coating layer, one with no coating layer, and one with no coating layer.
rrr Anaaki has shown a comparative diagram of the processing results. As can be understood from the figure, it has been shown that the cutting force provided with the coating layer is suppressed and wear is reduced. With the above configuration, the following effects can be obtained. (1) As shown in Fig. 2, torsional rigidity is greatly improved. The same applies to bending rigidity. (2) Figure 11 shows an example in which the work material is 550C, HB240°, cutting speed is 50m/min, and a φ8.5 drill is used.The drill obtained with the present invention has a torque close to that of conventional drills,
Compared to a conventional drill with a negative radial rake angle and a drill with a core thickness hole and groove width ratio, its torque and thrust are significantly lower. (3) By shortening the relative distance between the cutting edge and the groove wall at the outer periphery of the drill, chips can be cut and ejected from within the drill slot, improving evacuation efficiency. The embodiments shown in FIGS. 4 and 5 are for the case where the rake angle θ in the radial direction is Oo, but in FIG.
shows an example where has a positive rake angle. The effect further enhances the above-mentioned effect. Further, FIG. 7 shows a case in which the cutting edge is formed in a concave curved shape with an angle of 15° to positive at the outer circumference of the drill. In this case, the generation of chips is shared by the longer cutting edge, so it is carried out smoothly, and the longer cutting edge length reduces the amount of work per unit length of the cutting edge, improving wear resistance. It becomes possible. Also, in Figure 6 there is a double margin, that is, a margin part 4.5.
As a result, not only the hole accuracy is improved, but also chips are prevented from flowing into the second outer circumference part, and cutting can be performed smoothly. However, these effects are due to the fact that the cutting edge is TLCN and Tic. 11-1... Cutting edge 4.5... Margin A & By being coated with a thin film such as 203, it is more effective and the advantages of the super hard alloy are fully utilized. 4. Brief explanation of the drawings Figure 1 is an end view of the drill, Figure 2 is a curve showing the relationship between core thickness and groove width ratio on torsional rigidity, and Figure 3 is a diagram showing the state of chips in a conventional drill. 4 is an end view of the drill of the present invention, FIG. 5 is a side view of FIG. 4, FIG.
Figure 7 is an end view of another embodiment, Figure 8 is a comparison diagram showing the flow of chips, Figure 9 is an explanatory diagram showing the relationship between drill diameter and cutting edge length, and Figure 10 is a conventional drill. Figure 11 is a comparison diagram of test results showing the relationship between thrust, l-lux and feed in drills of various shapes, Figure 12 is the thrust with and without a coating layer, 1 ~
Fig. 13 is an experimental comparison diagram showing the relationship between torque and feed, and shows experimental values showing the relationship between the outer peripheral margin and the number of holes drilled. R...Groove width ratio BAA C...Core thickness D...Drill diameter θ...Rake angle 12- Patent applicant Sumitomo Electric Industries Co., Ltd. agent For patent attorney 1) Showa 10 r scratches Pe9゛ JP-A-114407 (10) 12th yA C゛/ 1'N+-(・ , -1 1st 13i! 1 0% < ull-[)4 Cst-161, -, c. 1111 Sword ■・1q

Claims (4)

[Claims] (1) In a drill made of ultra-hard material, the core thickness is 25 to 35% of the drill diameter, the groove width ratio is 0.4 to 0.8:1, and the radial rake angle of the cutting edge when viewed directly from the end is at least the drill diameter. On the outside of 2/3 of the groove wall, a perpendicular line is drawn from the outer periphery of the groove wall to the reference line using the cutting edge that is at least 2/3 outside of the drill diameter when viewed directly from the cutting edge as a reference line. Assuming that the distance between the perpendicular line and the outer periphery of the cutting edge is 47% or less of the drill diameter, and part or all of the cutting edge is TLN, TLC, TLCN or M20.
A drill characterized in that one or more types of j are coated directly or through another layer. (2) The shape of the cutting edge in direct view from the core thickness to the outer periphery of the drill is a concave curve so that the rake angle in the radial direction of the cutting edge outside 2/3 of the drill diameter is at least positive. Claim No. 1 (1) characterized in that
) Drill described in section. (3) In addition to providing a margin on the outer diameter at the cutting edge position,
The drill according to claim 1 or 2, characterized in that the drill is also provided on the opposite side of the cutting edge. (4) A portion of the coated cutting edge includes at least the rake face,
Claim No. 1 characterized in that it is a margin.
), the drill described in paragraph (2) or paragraph (3).