JPS583616Y2 - drilling tool - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a drilling tool, and particularly provides an indexable drilling tool that achieves cutting balance through a rational arrangement and combination of a center cutting edge and a peripheral cutting edge.

Twist drills, which are conventionally used as drilling tools, have cutting edges that are symmetrically formed around the nazel, so the cutting forces exerted on the cutting edges are balanced with each other. .

However, in the case of drills that use indexable inserts, there are problems such as the inability to accurately position the nazel when replacing the indexable insert, and the need for a clamping mechanism that can withstand the cutting force applied to the nazel. have.

Therefore, in indexable drilling tools, there is a need to develop an asymmetrical cutting blade configuration that improves the cutting balance between the center cutting edge and the peripheral cutting edge.

The present invention was developed in view of the above-mentioned points, and provides a drilling tool in which throw-way tips with different shapes are arranged on the center side and on the outer circumference side, so that the cutting balance can be maintained. An embodiment of the drilling tool of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a cylindrical tool body, and indexable naps 2 and 3 are arranged in nap seats 5 and 6 in the flute groove 4, respectively.
It is fixed by a presser foot 7.

The throw-away nap 2 is arranged in the chip seat 5 near the center of the tool body 1, and has a triangular plate shape with a portion of its apex cut off, and has a shallow V-shape formed by the cut. The side portion shown is located on the front side in the drilling direction.

Then, the long side part is aligned with the main cutting edge 8 at an angle of α.
The short side portion constitutes the auxiliary cutting edge ridge 9.

Further, the intersection point 12 between the main cutting edge ridge 8 and the sub-cutting edge ridge 9 is somewhat deviated from the rotation center line 13 of the tool body 1.

On the other hand, the throw-away nap 3 has a square plate shape and is disposed inside the chip seat 6 on the outer peripheral side, and its main cutting edge 10 is located near the cutting edge of the minor cutting edge 8. It is positioned at an angle of β at the rear.

As can be seen from the figure, this angle β is smaller than the angle α.

The indexable nuts 2 and 3 are attached to the nap seats 5 and 6 in the illustration using a presser foot 7, but various types of presser foot 7 may be used. has an oil hole 11 open toward its tip, and the cutting oil allows smooth discharge of chips.

The drilling tool of the present invention configured in this way has a throw-away nut 2 disposed on the center side and the outer peripheral side,
3, the relationship between the angles α and β formed by the main cutting edge 8° 10 is α>β, and for the indexable nap 2, the relationship between the main cutting edge 8 and the minor cutting edge 9 is By making the intersection point 12 deviate by δ with respect to the rotation center line 13 of the tool body 1, the cutting balance is improved.

In order to explain that the cutting balance is improved, Fig. 3 conceptually shows the balanced state of the cutting force in the drilling tool of the present invention, and in particular, the component force Fr in the center direction is kept in a balanced state. .

That is, the drilling tool of the present invention has the following effects on the workpiece 14:
Drilling a hole with a radius of R, the throw-away nap 2
, 3, the angles α and β of the main cutting edge edges 8° and 10 are set to α>β from the relationship of cutting balance, and the deviation amount δ from the rotation center line 13 and the angles of the main cutting edge edges 8 and 10 are set to α>β. Shared cutting width A due to crossover.

B is given respectively.

In this case, the auxiliary cutting edge 9 associated with the deviation amount δ has an angle α' in order to prevent damage due to thrust and rotational force, and δ is (1/3 to 1/4) due to the cutting width. The shared cutting width is set at A:B-=1:1.

In addition, in Fig. 3, each cutting edge 8°9.10
The cutting force generated in is given as follows, and the relationship α>β is obtained.

The back force is generated in the direction perpendicular to the cutting edge edges 8, 9, and 10, and is F Vl s F V2 s F, respectively.
V3, and when the cutting force is viewed as a vector quantity, the scalar quantity is approximately given by the following formula, although it differs somewhat due to the influence of cutting speed.

F Vl +F v2=:F V3 ・−・+−(1
) From the relationship of the cutting width, %FV2 is set as shown in the following formula.

F ■, = (1/3~1/4') Fv2=
(2) On the other hand, the component toward the center (F rl s F
r2 mFr3), thrust direction component (Ftl, Fr2
．． Ft3') is determined from the thrust force described above, and in particular, a state in which the center-direction component force is balanced is expressed by the following equation.

-1 -chi -→ F r2- F r, :F r3 ·-·- (3) And each F rla F r2 z F r3 is expressed as follows.

Fr1=tanα'FvI Fr2=tanαF■2 °-Tune (4) Fr3=tanβFv3 Substituting (4) into (3), tan a Fv2- tana' Fv, = ta
nβF V3 Here, since α=α′, tanα(Fv2−Fv, )=tanβFv3 Therefore, as is clear from equations (1) and (2), F v2 F vl<F V3 Kara tan
α)tanβ.

Therefore, α>β.

As a result, the angle α needs to be larger than the angle β as a condition for balancing the central direction components F rl * F r2 x F r3 occurring at each cutting edge edge 8, 9, 10.

This means that even if the cutting edges 8, 9, 10 are asymmetrical, the cutting components in the center direction need only be balanced.

Note that taking an extremely large value for the angle α is not good for cutting edge damage and chip flow, and in general, α=
The range of 10'-20'(7) is good, and the angle of β with respect to this is in the range of β=3°-7'(7).

If it is within this range, the conditions during cutting will be stable, the precision of the hole to be machined will be improved, and the drilling machine tool will not be subjected to vibration, allowing good cutting to be performed.

The drilling tool of the present invention has indexable inserts with different shapes on the center side and outer circumferential side arranged in the tool body, and the cutting force is distributed so as to be balanced in the center direction depending on the angle and amount of deviation of the cutting edge. It has the advantage of enabling highly efficient processing.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the drilling tool of the present invention;
FIG. 2 is a bottom view thereof, and FIG. 3 is an explanatory diagram conceptually showing the state of cutting force.

Claims (1)

[Claims for Utility Model Registration] A drilling tool in which indexable knobs 2 and 3 are disposed on the center side and on the outer circumferential side, respectively, at the tip of a rod-shaped tool body 1, wherein the indexable thumb 2 is located at the top of the tool body 1. It has a substantially triangular plate shape with some corners cut off, and when placed on the center side of the tool body 1, the side part that has a shallow V shape due to the cut is positioned on the front side in the drilling direction, and its length is The side part is α
The main cutting edge ridge 8 has an angle of , and its short side constitutes the auxiliary cutting edge 9, and the intersection point 12 of the main cutting edge 8 and the auxiliary cutting edge 9 is the rotation center of the tool body 1. The throw-away nap 3 has a deviation amount δ with respect to the line 13, and the throw-away nap 3 is made of a square plate shape, and on the front side of the tool body 1, near the cutting edge of the auxiliary cutting edge ridge 9. A main cutting edge 10 is configured to have an angle β smaller than the angle α at the rear of the drilling tool.