JPS6246490Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<Industrial Application Field> The disclosed technology belongs to the technical field of drills used for drilling holes in cast iron, steel, etc., particularly the structure of drills using cemented carbide as a material. <Summary> This invention has a chamfer formed from the rake face to the flank face at the intersection of the rake face and the flank face on the cutting edge of the tip of the drill body to reduce the brittleness of the cemented carbide. This invention relates to a drill structure that aims to strengthen the cutting edge by reinforcing it, and in particular, the chamfer angle is larger at the center chamfer and smaller at the periphery, ranging from 10° to 45° with respect to the drill axis. ,
In addition, the chamfer width is 0.03 to 0.3 mm, and it is large near the center and small near the outer periphery.
Furthermore, this invention relates to a drill structure in which the ratio of the two is formed in a range of 3:1 to 2:1 to further improve wear resistance. <Prior Art> As is well known, high-speed, rigid drills have been used for drilling holes in general steel materials, cast iron products, etc., but as there is a strong demand for higher efficiency in the drilling operations. In recent years, there has been an increase in the number of drills increasing their rotational speed to meet these demands.
Along with this, drills having a structure in which the cutting edge portion of the drill is made of cemented carbide, which has excellent wear resistance, have come into use. For example, in the drill 1 shown in Figures 1, 2, and 3, cemented carbide is used for the cutting edge 2, and the thinning 3 is cross thinning, and the chisel width is almost zero. However, cemented carbide is brittle and has poor transverse rupture strength, and when concentrated force is applied to the cutting edge during interrupted cutting or heavy cutting, there is a risk that small chips or other chips may occur.
Chamfering of so-called negative land etc. 4 in order to strengthen
is formed from the rake face 5 to the flank face 6, and generally the chamfer angle θ for the chamfer 4 is 10° to 45° with respect to the axis 7 of the drill, and the chamfer width on the rake face 5 side is about 0.03 to 0.3 mm. The ratio was kept almost constant over the entire length of the cutting edge 2. Furthermore, when considering the cutting resistance, such cutting edge treatment leads to an increase in the resistance, and therefore,
If possible, it is better not to have a cutting edge treatment, and such treatment is often unavoidable in order to accommodate the above-mentioned characteristics. <Problems to be solved by the invention> By the way, there are the following characteristics problems when drilling a hole in a steel material using a drill having a cemented carbide cutting edge. In other words, the cutting speed at the center of the cutting edge is low when drilling first, so the temperature due to cutting does not rise that much, and although wear resistance is not so necessary, on the contrary, welding is difficult. The cutting edge itself becomes chipped when welds form or fall off. On the other hand, the cutting speed is high at the outer periphery, and it also increases as it moves from the center to the outer periphery, and naturally wear resistance is required. Generally speaking, the larger the chamfer is for strengthening the cutting edge, the greater the amount of heat generated, and the worse the wear resistance. Therefore, as mentioned above, in forming a chamfer from the rake face to the flank face of the cutting edge in the conventional mode, the chamfer width is constant in ratio over the entire length,
Furthermore, if the chamfer angle is constant, there is a problem in that the wear resistance from the center to the outer circumference deteriorates. <Purpose of the invention> The purpose of this invention is to solve the technical problem of forming a chamfer from the rake face to the flank face of the cutting blade of a drill having a cutting blade made of cemented carbide based on the above-mentioned conventional technology. The challenge was to process the shape of the drill chamfer from the rake face to the center to make the wear resistance of the cemented carbide cutting edge uniform, and to find the optimal cutting edge treatment to suit the usage conditions from the perspective of cutting resistance. Increase the size to prevent damage,
It is an object of the present invention to provide an improved drill structure that will benefit machining technology applications in the metal products manufacturing industry by extending the overall life of the drill. <Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of this invention, which is based on the above-mentioned claims for utility model registration, is to make the cutting edge of the drill made of cemented carbide. and form a chamfer at the intersection between the rake face and the flank face, and in this case, the chamfer angle should be in the range of 10° to 45° with respect to the drill axis, and
The chamfer width is 0.03 to 0.3 mm on the rake face side.
The chamfer is large near the center and small near the periphery, and the ratio is 3:1 to 2:1 between the center and periphery, and the ratio of the chamfer angle is the same between the center and periphery. 3:1 to 2:1
This is a technical measure that improves the life of the drill by imparting uniform wear resistance from the center to the periphery of the cutting edge. <Embodiment - Configuration> Next, an embodiment of this invention will be described as follows based on the drawings from FIG. 4 onwards. Furthermore, the first
3. Components having the same features as those in FIGS. In the embodiment shown in FIGS. 4 to 7, 1' is a drill that forms the center of the gist of this invention, and its cutting edge 2 is made of cemented carbide, and in the illustrated embodiment, a cross thinning 3 is formed. , the chisel width is almost zero, and its rake face 5 to flank face 6
A chamfer 4' is formed throughout. Therefore, the chamfer angle θ of the chamfer 4' is constant toward the center and toward the periphery, and θ=25
The chamfer width is wide at the center and narrow at the periphery, numerically speaking, for a drill with a drill diameter of 10 mm, the chamfer width is 0.2 at the center.
mm, 0.07 to 0.1 mm near the periphery, and drill diameter 20 mm
0.3mm closer to the center and 0.1~0.15 closer to the periphery
mm and its ratio is considered to be approximately 3:1 to 2:1. <Example - Effect> In the above configuration, the shape is made as shown in Figures 1 and 2 by cross thinning with a diameter of 10 mm, a core thickness of 2.5 mm, a groove width ratio of 1:1, and a chisel width of 0.1 mm, and the material is cemented carbide. Prepare three P30 sample drills A, B, and C.
The cutting edge processing width (mm) was as shown in the following table.

[Table] Also, the chamfer angle was kept constant at 25°. As for the hole drilling test for the board, the board is
S15C H _B 150, cutting speed 50m/min,
In addition, the feed rate was set to 0.3 mm/rev depth to 30 mm. Note that the cutting oil used is an emulsion type. For each sample drill, the number of holes drilled until the center part breaks due to welding is repeated three times each, and the data is as shown in Figure 12.
The marks indicate holes that were discontinued due to chipping during drilling. Drill A had defects at holes 682, 795, and 886. Also, with B and C drills, up to the 1000th hole was drilled, but there was no breakage. FIG. 13 shows the average value of the amount of wear on the outer periphery (maximum wear on the outer flank flank) with respect to the number of holes, and it can be seen that the amount of wear at the 650th hole in the A drill is 0.1 mm. As can be seen from the data, it is clear that the chamfer is larger towards the center and narrower towards the periphery, which has better wear resistance. It can be seen that chipping occurs. The cause of this is that because the workpiece material is SISC, a low-carbon material, there is a lot of welding, especially in the center area where the speed is low, and chipping occurs when the welding falls off. Furthermore, in the embodiments shown in FIGS. 8 to 11, the chamfer angle of the above-mentioned embodiment is the same both toward the center and toward the periphery, and the chamfer width is wider toward the inner center and narrower toward the periphery. In contrast,
The chamfer width is the same as in the above example, and the chamfer angle is 30 degrees near the center and 10 degrees near the periphery, making it larger toward the center and narrower toward the periphery. was almost constant, and it was found that the embodiment of this invention is superior to the conventional embodiment. It goes without saying that the embodiment of this invention is not limited to the above-mentioned embodiments. For example, for chamfering, both the chamfer angle and the chamfer width may be made larger near the center and smaller at the center of the periphery, so that the ratio of the two is adjusted respectively. Various embodiments such as formation at a ratio of 3:1 to 2:1 can be adopted. Considering chipping at the center, it can be said that it is better to have a large cutting edge treatment at the center, but as shown in Figure 14, if the cutting edge width is wide, cutting resistance (especially thrust) will increase, so if On the other hand, if it is used in a machine with low rigidity, it may become chipped. Therefore, it can be said that it is an effective means to enlarge only the necessary central part, rather than uniformly enlarging the whole. The drill used in Figure 14 has a diameter of 21.5 mm.
Core thickness 6.4mm, groove width ratio 0.8:1, cross thinning with chisel width 0.1mm, internal oil supply hole made of TiN material P30
The cutting conditions were a rotation speed of 50 mm/min and a depth of 40 mm in the S50C workpiece. Also, emulsion type cutting oil was used. <Effects of the invention> As described above, according to this invention, in a drill in which the cutting blade material is basically made of cemented carbide and a chamfer is formed at the intersection of the rake face and flank face, the chamfer width is set to the rake face. 0.03~0.3mm on the side,
However, by forming the ratio of 3:1 to 2:1, which is larger near the center and smaller near the periphery, the cutting speed is higher and the cutting temperature is lower at the outer periphery of the cutting edge. The excellent effect of suppressing heat generation and improving wear resistance even when the cutting edge is increased is achieved, and the optimal design achieves average wear over the entire cutting edge, resulting in a significantly longer drill life. This produces an excellent effect. Moreover, since the overall cutting edge treatment is not large, it does not lead to an unnecessarily increased resistance, and troubles caused by cutting resistance can be prevented. In addition, since there is little wear on the flank surface, an excellent effect is achieved in that the strength of the cemented carbide cutting blade is always maintained to the extent that it is strengthened by chamfering.

[Brief explanation of the drawing]

Figure 1 is a top view of the tip of a conventional drill using cemented carbide as the cutting edge material, Figure 2 is a side view of Figure 1,
Figure 3 is a sectional view of Figure 2
The figures below are explanatory diagrams of the embodiment of this invention, and the fourth
The figure is a top view of one embodiment, Figure 5 is a side view of Figure 4,
Figure 6 is a sectional view taken along the Y-Y line in Figure 5, and Figure 7 is a cross-sectional view taken along the line Z in Figure 5.
-Z sectional view, Figure 8 is a top view of another embodiment, Figure 9 is a top view of another embodiment.
The figure is a side view of Fig. 8, Fig. 10 is a Y-Y cross-sectional view of Fig. 9, Fig. 11 is a Z-Z cross-sectional view of Fig. 9, and Fig. 12 is an explanation of the relationship between the number of holes processed by the sample drill and its life Graph diagram FIG. 13 is a graph diagram illustrating the relationship between the number of holes to be machined and the maximum wear on the outer circumferential flank face, and FIG. 14 is a graph diagram illustrating the characteristics of torque and thrust with respect to feed rate in another embodiment. 2... Cutting edge, 5... Rake face, 6... Relief face,
4', 4''...Chamfer, 1', 1''...Drill,...
... Chamfer width, θ... Chamfer angle.

Claims (1)

[Scope of claim for utility model registration] (1) In a drill structure in which cemented carbide is used as the cutting edge material and a chamfer is formed at the intersection of the rake face and flank face, the chamfer angle is 10 mm with respect to the drill axis. The chamfer width is in the range of 0.03 to 0.3 mm on the rake face side, larger near the center and smaller near the periphery, with a ratio of 3:1 to 0.3 mm.
A drill structure characterized by being formed at a ratio of 2:1. (2) A drill structure characterized in that the chamfer angle is larger toward the center and smaller toward the periphery. (3) A drill structure characterized in that the ratio of the chamfer angles closer to the center and closer to the periphery is 3:1 to 2:1.