JPS59161208A - Rolling cutter - Google Patents

Abstract

PURPOSE:To make it possible to carry out smooth cutting in a rolling cutter for drilling, end-milling, etc., by forming a concave part in the center of the cutting edge end of a tool having one or two cutting blades so that one side of the concave part is used as a cutting edge and is contiguous with the outer peripheral side cutting edge. CONSTITUTION:In the case of a twist-grooved drill having a pair of cutting blades 11, 111 each of which is made of an ultra-hard metal alloy from the front end to the terminal end of the blade, a drill body 1 is formed with twisted swarf discharge grooves 12a, 121a in addition to the cutting blades 11, 111, and is also formed, at its end surface, with relieving surfaces 13, 131 having a predetermined relieving angle. A concave part having a gap S and tapered toward the axial center 10 of the tool at an angle of theta, is formed in the center of the tool. The ridgelines defined between an inclined surface 15 of the concave part on the rear side, in the rotational direction, of the tool and raking surfaces 16, 161 on the front side, in the rotational direction, of the tool are used as center section cutting edges 14, 141. Further, center side cutting edges 17, 171 which are the ridgelines defined, as cutting edges, between the relieving surfaces 13, 131 and the raking surfaces 16, 161 are made contiguous with the cutting edges 14, 141.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a milling tool, such as a drill or an end mill, which mainly performs axial machining of the tool.

Conventionally, milling tools such as drills and end mills that mainly perform axial machining have a cutting edge configuration at the center of the cutting edge that is not suitable for axial machining. In other words, in a drill, a large negative rake angle is formed near the center of rotation where the rotation is extremely slow, and in an end mill, a large negative rake angle is formed at the center. Effective machining cannot be expected, and in end mills, it is near the center. The cutting edge may be damaged.

The above will be specifically explained below using the conventional drill shown in FIGS. 1 and 2 as an example.

A cutting edge 11.11□ and a helical groove 12 are provided at the end of the drill body 1.
．． 12□ and the outer periphery have margins 13 and 131
are provided on the end face from the cutting action of the cutting blades 11, 11□. A chisel edge 17 is formed at the center portion 15 of the tip. Cutting edge 1 of this drill
1.11□ has a predetermined positive rake angle in the ° axis direction, so it rarely causes problems during cutting, but the chisel edge 17 mentioned above has a negative rake that is equal to the drill tip angle. It is a corner. During cutting with this Tamedrill, the cutting h1j at the chisel edge increases the thrust load during "squeezing" and "scraping" cutting, which causes wear and damage to the chisel edge of the drill, shortening its life.

In addition, a problem with drills with chisel edges is that they have poor biting properties and problems with centripetal properties, which can cause center runout and create triangular, pentagonal, or triangular shapes during initial cutting.
A rice ball-shaped hole is drilled, and this results in the cut hole being deformed or having poor surface accuracy.

In the past, various shapes of thinning 16, 161 have been proposed and implemented in order to solve some of the above-mentioned problems, but the reality is that they all have advantages and disadvantages and have not solved the fundamental problem.

The present invention was made to solve the above-mentioned problems, and it improves the center part of the cutting edge of a tool that performs axial cutting, such as a drill or end mill, and reduces the thrust load during drilling and cutting. It is an object of the present invention to provide a milling tool that can improve coreability and prevent wear or damage to the central portion of the cutting edge.

Hereinafter, one embodiment of the present invention will be described based on the attached third tooth to FIG. 8.

Figure 3 shows only the main parts of a helical grooved drill that has a pair of cutting blades made of cemented carbide from tip to end, and (a) in the same figure shows a bottom view of the center of the cutting blade. ,same(
b) is a side view of the central portion of the cutting blade viewed from the direction of arrow A, and (C) is a side view of the central portion of the cutting blade viewed from the direction of arrow B, in which the drill body 1 has a pair of outer peripheries. Cutting blade 11,
11. 1. Flank surfaces 13, 13□ are formed at a predetermined clearance angle on the twisted chip discharge groove 12al12□a and the end face thereof. The tool axis is set at an angle θ (usually 5 to 175 degrees, 120 degrees in the example) with a distance S (usually 0.02 mm to drill diameter x, 3 yrm) as shown in Figure (C) with the tool center 10 as a reference. forming a concave portion that slopes toward the center 10;
The ridge line formed by the inclined surfaces 15, 15□ on the rear side of the tool rotation of the recess and the rake face 16 on the front side of the tool rotation is defined as a central cutting edge 14.14□. Also, flank surfaces 13, 13
The ridgeline formed by □ and rake faces 16 and 16□ is the cutting edge, and the center side cutting edges 17 and 17□ are continuous with the cutting edges 14 and 14□, and the outer peripheral side cutting edges 11 and 111 are also cut in a broken line shape. The blades are continuous.

The effect produced by such a configuration is that the tool center 1
An effective cutting edge can be formed up to 0, and the rake face 1 near the center
6 can be formed at zero, positive, or gentle negative angles in the axial direction, so "squeezing" or "rubbing failure" during cutting, which occurs due to extreme negative angles like conventional rectangles, is continuous. The thrust load is large: the width is greatly reduced and the cutting edge wears in the center! Wear or loss may be reduced.

Moreover, from the center side cutting edge 17, 17□ to the center part cutting edge 14
, 14□ Since the cutting edge is inclined inward toward the tool center 10, the effective cutting edge becomes longer, and therefore the chips produced are longer and thinner. Chips do not weld.

Moreover, the cutting edges 17 and 171 on the center side and the cutting edge 14 in the center part
, 141 is obtuse, making it suitable especially when the material for forming the drill is cemented carbide, and at the same time, the cutting edges formed by the cutting edges and the various requirements mentioned above are suitable. They act synergistically to improve centripetal properties during initial cutting, and as a result, drilled holes with high precision and no core tension can be obtained.

The above results were proven by the following experiment.

Tools used: Conventional solid drill with drill diameter 20, drill according to the invention Machine used: Vertical milling machine 7, 5 Kw Cutting conditions: Work material: 555C (HB170-200), plate thickness 5
0 rotation speed: 850 rpm, feed per rotation: 0.3/rev, cutting oil: emulsion type water-soluble cutting oil (x 4 times), lubrication method: experiment with conditions higher than internal forced lubrication method As a result, the drill of the present invention has l
During the second wear of the center after cutting 5772, it was about 115 of the conventional drill.

Further, the cutting resistance (thrust) was approximately 85% of that of the conventional square shape.

Although the above-mentioned embodiments have been explained with respect to solid drills made of cemented carbide, the present invention is not limited to these materials, and it goes without saying that it may be used in cutting tools made of appropriate materials such as special steel. For example, it can be applied to a drilling tool in which a pair of hard interest tips 2, 2□ are brazed or mechanically fixed to the tip of a shank 1 made of a metal other than cemented carbide as shown in Figs. 4 to 6. It is. That is, what is shown in the figure forms center-side cutting edges 17, 17, which are circular arcs of large curvature that protrude toward the front side of rotation based on the vicinity of the tool center 10, and which are straight or have a curvature that is at the center. It has a continuous arc-shaped or wave-shaped outer cutting edge 11.11□ smaller than the side cutting edge, or the center cutting edge 17.1
From a predetermined position of 7□, inclined surfaces 15 and 15□ are formed with a predetermined angle of inclination in the same manner as in the embodiment described above.
, 16□ and the slanted surfaces 15, 15□ form a central cutting edge 14 and 14□ with the ridgeline as the effective cutting edge.
Since it has the same effect as described above and can form a large chip pocket, the chip discharge performance during cutting is further improved.

Next, an example will be described in which the present invention is applied to an end mill that performs axial cutting and lateral cutting. FIG. 7 ((a) is a bottom view showing only the main part of the cutting blade, and (b) is a side view of (a)) shows the main part forming the center cutting edge 11b and the outer cutting edge 12 from the vicinity of the tool center. A center side cutting edge 2 whose rotation locus is at the same position as the center side cutting edge 11 of the main cutting edge at a position excluding the cutting edge 1a and the center part.
The main cutting edge 1a and the auxiliary cutting edge 2a are provided with an auxiliary cutting edge 2a having a peripheral cutting edge 22, or the main cutting edge 1a and the auxiliary cutting edge 2a are provided with inclined surfaces 13a, 23 in the same manner as described above or previously described. However, if one of the surfaces is used as the central cutting edge 14.24, it will have the same effect as described above, allowing smooth cutting in the axial direction and preventing wear or breakage of the cutting edge. Note that, although the main cutting edge and the auxiliary cutting edge are shown as an example, a single blade having only the main cutting edge can also be used by providing the inclined surface 13a as described above.

Moreover, as in the drill shown in FIG. 8 ((a) is a bottom view showing only the main parts of the cutting blade, (b) is a side view of (a)), the tip lb, 1. Inclined surface 15 in the one having a center side cutting edge 17.17□ and outer peripheral cutting edges 11a, 11°a whose cutting edge starting ends are spaced apart from each other by a predetermined value from the center of the drill.
, 15□, and it is also effective to form one of these inclined surfaces as a cutting edge 14°14 in the center portion.

As described above, the present invention has the cutting edge of a milling tool recessed, one of the recessed portions serves as a cutting edge, and this is continuous with the outer peripheral cutting edge, so that the center of the tool is An effective cutting edge can be formed up to the tip of the cutting edge, allowing for smooth cutting.This reduces cutting resistance and prevents wear or chipping of the starting edge of the cutting edge. It is an economical milling tool with a long life that is easy to manufacture, and which eliminates the various disadvantages of conventional chisel edges that make it possible to drill holes with high precision, which can sometimes cause center runout.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional IJ. Figure 1 is a front view, Figure 2 is a bottom view of Figure 1, and Figure 3 is a bottom view of Figure 1.
Figures 8 to 8 relate to the present invention, and Figure 3 (a)
is a bottom view of the center of the drill, (b) is a side view taken from arrow A in (a), (C) is a side view taken from arrow B from (a), and Figures 4 and 5 are views of other implementations. An example is shown in Figure 4 (front view), Figure 5 is the bottom view of Figure 4, and Figure 6 is the bottom view of Figure 4.
(A) is a bottom view, (b) is a view from arrow A in (a), (c) is a view from arrow B in (a), (d) is a detailed view of Figure 5.
(a) is a view taken in the direction of arrow C; FIG. 7 (another example; (a) is a bottom view of the main part of the cutting blade; (b) is a side view of (a); FIG. 8 is another example). In this example, (a) is a bottom view of the main part of the cutting blade, (b)
(Ma) Side view of (a), etc. 1-m-drill body 1b, 1□b, 2.21--chip 10-11 tool center 11.1111.11a
, 111a, 12.22-m-outer cutting edge 13.131
-11 Flank surface 14.141.24-m-Cutting edge in the center 1.3a,'15.15□ 23-m-Slanted surface 1
1b, 17.17□ -m-Center side cutting edge No. l Fig. @2 cause No. 3 Fig. 4 Fig. 6 Fig. tσ

Claims (1)

[Claims] (1) A tool having one or two cutting edges is characterized in that the center of the tip of the cutting edge is recessed, one of the recessed portions serves as a cutting edge, and this is continuous with the outer cutting edge. Milling tools.