JPH11197923A - Throw-away drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively restrain vibration of a tip installed on a drill main body. SOLUTION: A fitting hole 15 which is concentric with an axis O and extended to the base end side is formed in a groove bottom 14A of a recessed groove 14 formed extending from the tip of the drill main body 11 toward the base end part. A fitting shaft part inserted in the fitting hole 15 is provided in the rear end 21A of the tip main body. Further, the fitting shaft part has a notch 22 where a conical point part 23a of a clamp screw 23 can be engaged, which is formed to be recessed from the outer peripheral surface toward the radial inside. An axis Z in the recess direction of the notch 22 is eccentric to the axis Y of the clamp screw 23 so that as the clamp screw 23 is tightened, a tip 21 is pressed to the rear side in the drill rotating direction R and the base end side of the drill main body 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type drill in which one throw-away tip is detachably fixed to the tip of a drill body, and more particularly to an improvement in a structure for fixing a throw-away tip.

[0002]

2. Description of the Related Art For example, as a technique for improving a tip fixing structure of a throw-away type drill in which one throw-away tip (hereinafter, simply referred to as a tip) is detachably fixed to a tip portion of a drill body, Tokuhyo Hei 8-503
No. 423 is known.

In this throw-away drill, as shown in FIG. 7, a tip 3 is inserted into a concave groove 2 formed from the distal end of the drill body 1 toward the base end, and the tip 3 is inserted from the outer periphery of the drill body 1. The tip 3 is drilled by engaging the tips of two clamp screws 4 screwed obliquely to the upper and lower surfaces 3a, 3b with the notches 5 formed in the upper and lower surfaces 3a, 3b of the chip 3. It is fixed to the main body 1, and has the advantages that the strength of the drill tip does not decrease and the tip can be replaced quickly and easily.

[0004]

However, in the throw-away type drill having the above structure, the tip of the clamp screw 4 is flat, and the corner of the tip is engaged with the notch 5 in the upper and lower surfaces 3a and 3b of the tips. Since the tip 3 is pressed and fixed by tightening the clamp screw 4, the holding force of the tip in the direction along the axis of the drill body 1 is weak.

[0005] For this reason, the cutting resistance acting on the tip 3 acting in the axial direction of the drill body 1 when the drill bites into the work material, when the drill is pulled out during drilling of a through hole, or when the drill is pulled out, is reduced. When the tip 3 fluctuates greatly (increase or decrease), vibration occurs in the chip 3 and processing becomes unstable, resulting in a defect such as chipping or damage to the chip 3 or a reduction in processing accuracy. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses a clamp screw to insert a tip into a back metal of a drill body, that is, a portion of a groove in the drill body on the groove rotation side rearward in the direction of drill rotation, and a base end of the drill body. An object of the present invention is to provide a throw-away type drill that can effectively suppress the vibration of a chip by simultaneously pressing the drill against the side.

[0007]

The present invention has the following features to attain the object mentioned above. That is, in the throw-away type drill according to claim 1, one flat plate-shaped tip is inserted into a concave groove formed from the distal end of the drill main body toward the base end side, and is inserted into the axis of the drill main body. In a throw-away drill fixed to the drill body by engaging a notch formed in the tip with a tip end of a clamp screw screwed from an outer peripheral side toward the tip, the tip has the concave at a rear end thereof. A fitting shaft is inserted into a fitting hole formed further from the groove bottom surface toward the base end side, and the notch is formed so as to be recessed radially inward from an outer peripheral surface of the fitting shaft. The notch is characterized in that the axis of the notch in the concave direction is eccentric to the tip side of the drill body and the outer periphery of the drill body.

In such a configuration, when the clamp screw is tightened, the tip is pressed toward the rear side in the drill rotation direction and toward the base end of the drill body. A pulling force acts on the side. Therefore, the tip is firmly held by the drill body in a state where the tip is pulled toward the base end side of the drill body while being pressed against the back metal of the drill body by one clamp screw.

The indexable drill according to claim 2 is the indexable drill according to claim 1,
The notch is formed so as to be concave in a conical shape, and an opening angle between inner peripheral surfaces in a cross section along the concave direction is set in a range of 60 ° to 120 °. is there.

In such a configuration, it is possible to prevent the tip strength and the tip strength of the clamp screw from being reduced due to an excessively small opening angle, and to prevent the tip pressing torque against the back metal side by setting the opening angle too large. In addition, it is possible to prevent the tip vibration suppression function from being hindered due to insufficient tip retraction force to the drill body base end side.

According to a third aspect of the present invention, there is provided a throw-away drill according to the first or second aspect, wherein the axis of the notch with respect to the axis of the clamp screw is directed to the distal end side of the drill body and the outer peripheral side of the drill body. Are set in the range of 0.05 mm to 0.5 mm.

With such a configuration, it is possible to prevent a situation in which the amount of displacement of the clamp screw tip in the direction of the notch dent is insufficient due to an excessively large displacement width, and the fastening force of the clamp screw is reduced. Is too small, it is possible to prevent the tip pressing torque toward the back metal side and the tip pulling force toward the base end side of the drill body from being sufficiently obtained, thereby preventing the vibration suppression function of the tip from being hindered.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a throw-away drill according to the present invention will be described below with reference to FIGS.

In these figures, reference numeral 11 denotes a drill main body formed in a substantially cylindrical shape centered on the axis O. The outer periphery of the front end of the drill main body 11 is open at the front end and rotates around the axis O. A pair of chip discharge grooves 12 that are twisted rearward in the drill rotation direction R toward the base end are formed with the axis O interposed therebetween.

As shown in FIG. 3, the shank portion 11 extends from the base end face 11A along the axis O inside the drill body 11.
A supply path 13 for lubricating coolant or the like is formed which extends to the distal end side through a and branches near the distal end and opens to the distal end surface of the drill body 11. As shown in FIG. 1A, a groove 14 is formed in the distal end portion of the drill body 11 so as to be recessed one step from the distal end surface to the proximal end side along the axis O.

The groove 14 is formed so as to cross the tip of the drill body 11 in the diametrical direction and open at both ends thereof on the outer peripheral surface of the drill body 11. A blind hole-shaped fitting hole 15 extending concentrically with the axis O toward the base end side of the drill body 11 is formed. A female screw portion 16 formed from the outer peripheral surface of the drill body 11 toward the axis O communicates with the fitting hole 15.

On the other hand, the tip 21 mounted on the tip of the drill body 11 is made of cemented carbide, cermet, ceramics, or a material in which a hard coating is formed on the surface of these materials by PVD, CVD, or the like. As shown in FIG. 4, a chip body 21a having a pentagonal plate shape and a fitting shaft portion 21b protruding in a columnar shape along the axis X from a rear end 21A of the chip body 21a. The axis X coincides with the axis O of the drill body 11 when the fitting shaft portion 21b is inserted into the fitting hole 15.

A notch 22 is formed in the fitting shaft portion 21b so as to be conically concave from the outer peripheral surface toward the inside of the radius. When the tip body 21 a and the fitting shaft 21 b are inserted into the concave groove 14 and the fitting hole 15, respectively, and the clamp screw 23 is screwed into the female screw 16, the notch 22 forms a conical tip of the clamp screw 23. 23a
Engage with.

Next, the formation location of the notch 22 in the fitting shaft portion 21b will be described with reference to FIGS. 5 (a) and 5 (b). FIG. 5A shows a state in which the rear end surface 21A of the chip 21 is in contact with the groove bottom surface 14A of the concave groove 14, and the conical tip portion 23a of the clamp screw 23 is engaged with the notch 22 of the fitting shaft portion 21b. FIG. 3 is a cross-sectional view schematically showing a state in which the user is about to make the state.

As can be seen from this figure, since the clamp screw 23 is screwed toward the axis X of the fitting shaft 21b, the axis Y of the clamp screw 23 coincides with the diameter direction of the fitting shaft 21b. On the other hand, the axis Z in the concave direction of the notch 22 is eccentric from the axis X by the eccentric width L1 on the outer peripheral side of the fitting shaft portion 21b, that is, in the radially outward direction. A part of the peripheral surface of the tip portion 23a is the inner peripheral surface 2 on the rear side in the drill rotation direction of the notch 22.
2a is pressed.

FIG. 5B shows the fitting shaft portion 21b formed by a plane including the notch axis Z in the state of FIG. 5A.
3 shows a longitudinal section in the length direction. As is apparent from this figure, the axis Z of the notch 22 is the axis Y of the clamp screw 23.
Eccentric width L at the tip end side (upper side in the figure) of drill body 11
When the clamp screw 23 is tightened, a part of the peripheral surface of the conical tip 23a is cut out by the notch 22.
The inner peripheral surface 22b on the base end side of the drill body is pressed.

However, in the throw-away type drill constructed as described above, when the clamp screw 23 is tightened, a part of the conical tip portion 23a is partially cut out.
1 to simultaneously press the inner peripheral surface 22a on the rear side in the drill rotation direction and the inner peripheral surface 22b on the base end side of the drill body.
As shown in (a), the chip 21 has a chip body 21a.
Torque T for pressing the upper and lower surfaces 21A and 21B of the drill body 11 against the back metal 24, and a drawing force F for pulling the tip 21 toward the base of the drill body in the groove 14.
And the backlash of the chip 21 is effectively suppressed.

Therefore, according to the throw-away type drill of the present embodiment, when the drill bites into the workpiece, when the through hole is drilled, or when the drill is pulled out, the drill body 11 extends in the axial direction. Even when the cutting force acting on the chip 21 is greatly increased or decreased, the vibration generated in the chip 21 is small, and damage to the chip 21 and reduction in processing accuracy can be prevented.

Further, such a function is provided by one clamp screw 23.
Therefore, the clamp structure of the chip 21 can be simplified, and the operation of attaching and detaching the chip 21 can be performed more easily.

In the present embodiment, the opening angle α formed by the inner peripheral surfaces in the cross section along the recess direction of the notch 22 is formed.
Is preferably set in the range of 60 ° to 120 °. The reason for this is that if the opening angle α is smaller than 60 °, the strength of the tip 21 and the tip strength of the clamp screw 23 decrease, and if the opening angle α is larger than 120 °, the back metal This is because the tip pressing torque T in the direction and the tip pulling force F toward the base end side of the drill body are insufficient, and it is not possible to effectively prevent rattling of the tip 21.

The eccentric widths L1 and L2 are preferably set in a range of 0.05 mm to 0.5 mm. The reason is that when the eccentric widths L1 and L2 are larger than 0.5 mm, the conical tip 23a of the clamp screw 23
The amount of insertion of the clamp screw 23 into the notch
And the eccentric width L
1. If L2 is smaller than 0.05 mm, the tip pressing torque T in the back metal direction and the tip pulling force F toward the base end of the drill body are insufficient, and in any case, the backlash of the tip 21 is effectively prevented. This is because it cannot be obtained. In FIG. 5A, the axis Y of the clamp screw 23 may be shifted from the axis X so that the axis Z of the notch 22 passes through the axis X.

In the present embodiment, the notch 22 formed in the fitting shaft portion 21b of the chip 21 is described as having a conical recess from the outer peripheral surface. However, the present invention is not limited to this. As shown in FIG. A notch 31 is formed so as to be concave in a shape, and a distal end portion 32 of a clamp screw 32 engaged with the notch 31 is formed.
a may be formed in a spherical shape. In such a case,
The same effect as described above can be obtained.

Also in such a configuration, the eccentric width of the notch 31 with respect to the axis Y of the clamp screw 32 toward the distal end of the drill body and the outer peripheral side of the drill body may be set in the same range as described above. preferable.

[0029]

As is clear from the above description, according to the present invention, the following effects can be obtained. (A) In the throw-away type drill according to the first aspect, when the clamp screw is tightened, a pressing torque to the back metal side and a drawing force to the base end side of the drill body are applied to the chip, so that the drill body during the machining. Even when the cutting force acting on the chip acting in the axial direction greatly changes, the vibration generated in the chip is small, and damage to the chip and reduction in machining accuracy can be prevented.

Further, since such a function can be achieved with one clamp screw, the clamp structure of the chip can be simplified, and the work of attaching and detaching the chip can be performed more easily.

(B) In the indexable drill according to the second aspect, the tip strength and the tip strength of the clamp screw can be prevented from lowering, and the tip pressing torque on the back metal side and the tip on the base end side of the drill body can be prevented. It is also possible to prevent the vibration suppression function of the chip from being lowered due to insufficient pull-in force.

(C) In the throw-away drill according to the third aspect, the fastening force of the clamp screw can be prevented from lowering, and the tip pressing torque toward the back metal and the tip pull-in force toward the base end of the drill body are sufficient. Therefore, it is possible to prevent a decrease in the vibration suppression function of the chip.

[Brief description of the drawings]

FIG. 1A is an enlarged sectional view of an essential part showing an embodiment of a throw-away drill according to the present invention, and FIG. 1B is a sectional view taken along line AA of FIG.

2A is a plan view of the throw-away drill shown in FIG. 1, and FIG. 2B is a front view of the throw-away drill.

3A is a plan view showing a drill body of the indexable drill shown in FIG. 1, and FIG. 3B is a front view of the drill body.

4A is a plan view showing a tip of the indexable drill shown in FIG. 1, and FIG. 4B is a side view of the tip.

FIG. 5A is a cross-sectional view schematically showing a state in which a clamp screw is about to be engaged with a notch of a chip fitting shaft portion in a state where a rear end surface of a chip is in contact with a groove bottom surface of a concave groove. FIG. 2B is a longitudinal sectional view of the same state.

FIG. 6 is an enlarged sectional view of a main part showing another embodiment of the present invention.

FIG. 7 is a plan view showing a conventional example of a throw-away drill.

[Explanation of symbols]

 Reference Signs List 11 drill body 14 concave groove 14A groove bottom 15 fitting hole 21 throwaway tip (tip) 21b fitting shaft 21A rear end of throwaway tip 22 notch 23 clamp screw 23a conical tip (tip of clamp screw) L1 , L2 Eccentric width O Drill body axis R Drill rotation direction Y Clamp screw axis Z Notch dent axis α Open angle

Claims (3)

[Claims] 1. A flat-shaped throw-away tip is inserted into a groove formed from a distal end of a drill body toward a base end side, and is screwed from an outer peripheral side toward an axis of the drill body. In the throw-away drill fixed to the drill body by engaging the notch formed in the throw-away tip with the tip end of the clamp screw, the throw-away tip has the concave groove at its rear end. A fitting shaft inserted into a fitting hole formed further from the groove bottom toward the base end side, and the notch is formed so as to be recessed radially inward from an outer peripheral surface of the fitting shaft. A throw-away drill, wherein the axis of the notch in the concave direction is eccentric to the tip of the drill body and the outer periphery of the drill body. 2. The method according to claim 1, wherein the notch is formed so as to be concave in a conical shape, and an opening angle formed by inner peripheral surfaces in a cross section along the concave direction is set in a range of 60 ° to 120 °. The indexable drill according to claim 1, characterized in that: 3. The eccentric width of the axis of the notch with respect to the axis of the clamp screw toward the distal end side of the drill body and the outer peripheral side of the drill body is both set in a range of 0.05 mm to 0.5 mm. The indexable drill according to claim 1 or 2, wherein the indexable drill is provided.