JP2006192553A - Insert for gun drill, gun drill holder, and insert type gun drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert type gun drill capable of reducing the cutting force and setting an insert in a holder detachably using a simple structure. <P>SOLUTION: The face 5a of the insert 5 is formed inclined in V-shape whose bottom consists of diagonals tying together the confronting apices of a hexagon, in which two of the three edges in two sets pinching each diagonal form cutting edges 5c and 5d having convex V shape, and the other edge among the three is furnished with a land 5e whose section perpendicularly intersecting the mentioned other edge has a shape of circular arc. The insert 5 is detachably attached to the insert mounting region A formed in the holder 3 furnished with an insert seat surface 3b and facing wall surfaces 3c-3e so as to protrude the cutting edges 5c and 5d toward the forefront of the holder 3 and face the land 5e to the outer periphery of the holder 3. By an adjusting mechanism 6 installed in the holder 3, the mounting position of the insert 5 is adjusted so that the desired diameter of processed hole is obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gun drill that performs deep hole machining on steel or the like, in particular, a gun drill insert that is attached to a spindle of a machine tool such as a machining center and has a detachable blade part, a gun drill holder for attaching the insert, and these inserts And an insert type gun drill consisting of a holder.

A gun drill is known as a tool to be used when forming a deep hole with a long length and forming a small hole diameter (about 5 to 60 mm) (see, for example, Patent Document 1).
In the gun drill described in Patent Document 1, the blade portion brazed to the holder is configured to include a cutting blade, an oil hole, a chip discharge groove, and the like. In such a so-called brazing type gun drill, When the blade part is worn by use, the blade part is used again after being ground again.
However, re-polishing required considerable skill, and it was the actual situation that the cutting performance of the gun drill was greatly influenced by the quality of this re-polishing.

For this reason, Patent Document 2 describes an insert type gun drill in which a plurality of protrusions and recesses are formed in each of the blade portion and the holder, and the blade portion and the holder are detachable.
JP 2004-66391 A Republished patent WO02 / 005990

However, in the insert type gun drill described in Patent Document 2, a plurality of protrusions and recesses are formed in each of the blade part and the holder, and the blade part and the holder are attached and detached by engaging the protrusions and the recesses. Since it is flexible, the processing of these protrusions and recesses is complicated, leading to an increase in the cost of the entire insert type gun drill.
Further, in the insert type gun drill described in Patent Document 2, the cutting blade itself has the same configuration as that of a conventional brazing gun drill, and has only a rake face parallel to the rotation axis. No consideration has been given to the reduction of the resistance, and as a result, in order to resist a large cutting resistance, a complicated engagement structure as described above has to be used.

  The present invention has been made in view of the above problems, and provides a gun drill insert, a gun drill holder, and an insert type gun drill that can reduce cutting resistance and that can be attached and detached with a simple structure. Objective.

In order to solve the above-mentioned problems and achieve such an object, the gun drill insert according to claim 1 has a convex V on the intersecting ridge line between the rake face and the flank face of the hexagonal plate-like insert. A V-shaped cutting blade is formed, and is detachably attached to the tip of the holder of the gun drill. The rake face of the insert has a diagonal line connecting the vertices located on opposite sides of the hexagon. Two sides of the hexagonal three sides sandwiching the diagonal line, at least one of the two sides of the set is the convex V-shaped cutting blade, The other one of the three sides is characterized in that a land portion having an arc-shaped cross section orthogonal to the other one side is formed.
The gun drill holder according to claim 2 is configured such that an insert having a hexagonal plate shape can be detachably attached and an oil hole extending in the axial direction is formed, with the axis interposed therebetween. An insert seat surface that extends from the tip portion in parallel to the axis, and rises from the insert seat surface, and faces a plurality of flank surfaces of the insert. And a mounting region of the insert having an opposing wall surface formed, and an adjustment mechanism for adjusting a mounting position of the insert attached to the mounting region, and a circumferential direction on the outer periphery of the holder A plurality of guide pads whose outer peripheral surfaces form an arc shape in a cross section perpendicular to the axis are provided extending in the axis direction at intervals. It is an feature.
In addition, the insert type gun drill according to claim 3 is configured such that the gun drill insert according to claim 1 is made to project into the gun drill holder according to claim 2, and the cutting blade is projected to the tip side of the holder, and the land portion is The holder is detachably attached toward the outer periphery of the holder.

According to the gun drill insert according to claim 1, by providing a rake face that is inclined in a V shape and giving a positive rake angle, the chip is reliably divided to reduce cutting resistance. In addition, the shape of the insert itself can be a simple hexagonal plate.
Moreover, since the arc-shaped land portion is formed, the strength does not decrease at the outer peripheral end of the cutting edge.
According to the gun drill holder of the second aspect, the insert can be attached with a simple configuration by providing the insert attachment region having the insert seat surface and the opposing wall surface, and the outer periphery of the holder is circumferentially arranged. With the guide pads provided at intervals, the cutting blade can be reliably held on the inner periphery of the work piece during cutting.
In addition, by providing an adjustment mechanism, it is possible to adjust the mounting position of the insert and obtain a desired hole diameter.
Further, according to the insert type gun drill according to the third aspect, the cutting force can be reliably divided and the cutting resistance can be reduced, so that the insert and the holder can be detachable with a simple configuration, and the cutting blade can be reliably connected. Can be maintained.
Moreover, it becomes possible to adjust the attachment position of an insert by an adjustment mechanism.
In addition, since the arc-shaped land portion is provided on the insert toward the outer periphery of the holder, it is possible to prevent the strength of the outer periphery of the insert from being reduced, and even if the mounting position of the insert is adjusted, the arc portion formed by the land portion can be prevented. By making the diameter (diameter) smaller than the diameter of the processed hole, the contact between the land portion and the work can be surely avoided.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3.
Here, FIG. 1 is a front view of an insert-type gun drill 1 (hereinafter simply referred to as “gun drill 1”) of the present embodiment, FIG. 2 is an enlarged view of a main part of the gun drill 1, and FIG. 3 is an X direction arrow in FIG. FIG. 4 is a side view of the insert 5 as viewed in the Y direction in FIG. 2, and FIG. 5 is a side view of the insert 5 as viewed in the Z direction in FIG.
A gun drill 1 shown in FIG. 1 includes a holder 3 provided with a shank at the tip of a driver 2, an insert 5 having a hexagonal plate shape screwed to the tip of the holder 3 by a mounting bolt 4, and attachment of the insert 5 And an adjustment mechanism 6 for adjusting the machining hole diameter by adjusting the position.
On the outer periphery of the holder 3, guide pads 7 having a predetermined length parallel to the axis L of the holder 3 are attached by brazing at four locations at intervals in the outer peripheral direction.

As shown in FIGS. 2 and 3, the holder 3 has a long round bar shape, and an oil hole 3 a that penetrates from the tip of the holder 3 to the driver 2 is formed.
In addition, a chip discharge groove G is formed in a predetermined length in parallel to the axis L at a tip portion on the opposite side of the oil hole 3a across the axis L at the tip of the holder 3 over the circumferential direction about 90 degrees. Yes.
In addition, an insert seat surface 3b is provided at the tip of the holder 3 so as to extend in parallel to the axis L so as to be connected to the chip discharge groove G and to place the hexagonal flat plate-like insert 5. Three opposing wall surfaces 3c, 3d, and 3e rising from the insert seat surface 3b are formed.

The opposing wall surface 3c is substantially parallel to the axis L, and the opposing wall surface 3d is formed at an angle of about 120 ° with respect to the opposing wall surface 3c when viewed from the front direction facing the insert seat surface 3b.
The opposing wall surface 3e is formed with an angle of about 120 ° with respect to the opposing wall surface 3d when viewed from the front direction facing the insert seat surface 3b.
The insert seat surface 3b and the three opposing wall surfaces 3c, 3d, 3e form an attachment region A for the insert 5.
In the present embodiment, the opposing wall surfaces 3c, 3d, and 3e are inclined surfaces that are gradually expanded from the insert seat surface 3b in accordance with the shape of the insert 5 described later.

In the center of the insert seat surface 3 b, a female screw 3 f for screwing the mounting bolt 4 is formed in a direction perpendicular to the axis L of the holder 3 to the outer periphery of the holder 3.
In FIG. 3, a pilot hole 3g is formed adjacent to the attachment region A at an angle of about 45 ° with respect to the opposing wall surface 3c. The pilot hole 3g is formed between the opposing wall surface 3c and the insert seat surface 3b. A part is cut out and formed from the outer periphery of the holder 3 to the front of the screw hole 3f.
A female screw 3h having a diameter of the prepared hole 3g is formed from the outer peripheral side of the holder 3 to the front of the opposing wall surface 3c.

The insert 5 has a hexagonal plate shape in plan view integrally formed of cemented carbide, cermet, or the like, and the surface forming the hexagon is a rake face 5a and extends along each side of the hexagon. The six peripheral surfaces are flank surfaces 5b.
As shown in FIGS. 2 and 3, in the present embodiment, the rake face 5a is rotationally symmetrical by 180 ° around its midpoint across a diagonal line connecting the vertices located on opposite sides of the hexagon. In addition to being formed, it is formed to be inclined in a V shape with the diagonal line as a valley bottom, whereby a relatively large positive rake angle is given to the rake face 5a.

Also, as shown in FIGS. 2 to 5, in the present embodiment, among the two sets of three sides sandwiching the hexagonal diagonal line among the intersecting ridgelines formed by the rake face 5a and the flank face 5b. Cutting edges are formed on two sides, a second cutting edge 5d that is substantially parallel to the diagonal line, and a first cutting edge 5c that intersects the second cutting edge 5d with an obtuse angle and inclines toward the bottom surface 5f. Are arranged in a convex V shape when viewed from the front direction facing the rake face 5a.
Of the intersecting ridgelines formed by the rake face 5a and the flank face 5b, the remaining one side of the two sets of three sides sandwiching the hexagonal diagonal is processed by cylindrical grinding so that a cross section perpendicular to the remaining one side is processed. A land portion 5e having an arc shape smaller than the hole diameter is formed.

That is, the insert 5 is formed with two sets of first cutting blades 5c, second cutting blades 5d, and land portions 5e that are 180 ° rotationally symmetrical around the midpoint with the diagonal line therebetween.
Each of the six relief surfaces 5b has an inclined surface shape with a relief angle extending from the rake face 5a to the bottom face 5f facing the rake face 5a, whereby the insert 5 of the present embodiment is It is a positive insert.
An attachment hole 5g for screwing the insert 5 to the holder 3 is formed in the center of the rake face 5a.

The mounting bolt 4 has a Torx-type head in the present embodiment.
The screw diameter of the mounting bolt 4 is smaller than the hole diameter of the mounting hole 5g described above, and the mounting position of the insert 5 screwed to the holder 3 by the adjusting mechanism 6 described later is set to the insert seat surface 3b. Can be adjusted along.

The adjustment mechanism 6 includes a columnar adjustment member 6a fitted into the prepared hole 3g, and a screw 6b screwed into the female screw 3h.
As shown in FIG. 3, an inclined notch 6c that can be pressed against one of the flank surfaces 5b of the insert 5 in the attached state is formed at the tip of the adjustment member 6a.

The guide pad 7 has a predetermined length parallel to the axis L from the tip of the holder 3 and is formed in a plate shape whose outer peripheral surface has an arc shape in a cross section orthogonal to the axis L.
In the present embodiment, the four guide pads 7 are brazed after being fitted into the concave grooves formed in the holder 3, and the outer periphery of the four guide pads 7 forming an arc shape is the holder. 3 is slightly outwardly protruded from the outer periphery of 3, and is approximately the same diameter as the machining hole diameter when the insert 5 is positioned on the holder 3.
As a result, the guide pad 7 is configured to support the gun drill 1 by being brought into sliding contact with the inner surface of the processing hole at the time of cutting.

The case where the gun drill 1 having the above-described configuration is used for cutting a workpiece (not shown) will be described.
The insert 5 is attached to the holder 3 so that the first cutting edge 5c and the second cutting edge 5d protrude from the tip of the holder 3, and the land portion 5e faces the outer periphery of the holder 3. Screwed with bolts 4.
The insert 5 is attached to the holder 3 so that the bisector of the angle formed by the first cutting edge 5c and the second cutting edge 5d is substantially parallel to the axis L.

The notch 6c of the adjustment member 6a inserted into the lower hole 3g is pressed against one of the flank surfaces 5b of the insert 5 when the screw 6b screwed to the female screw 3h is rotated in the forward direction. The
Thereby, the insert 5 is pushed by the adjusting member 6a and moved radially outward of the holder 3 to adjust the mounting position.
Specifically, the outer peripheral end of the second cutting edge 5d is adjusted to coincide with the outer periphery of the four guide pads 7 in the rotation trajectory around the axis L so as to obtain a desired machining hole diameter.

Further, the attachment state of the insert 5 to the holder 3 will be described in more detail. As shown in FIG. 2, the land portion 5 e is a back taper that slightly inclines toward the inner peripheral side from the front end to the rear end of the gun drill 1. It is attached so as to have an angle θ.
The back taper angle θ is 0 ° 30 ′ in the present embodiment.
Further, in FIG. 3, the bottom side of the first cutting edge 5 c formed to be inclined toward the diagonal line is attached to a so-called tip centering so that the bottom side is located on the bottom surface 5 f side with respect to the center O of the gun drill 1. It is done.

  As described above, the gun drill 1 in which the insert 5 is attached to the holder 3 is mounted on the main shaft of a machine tool such as a machining center, and is rotated about the axis L while cutting oil is being supplied to the oil hole 3a. Drilling of the work material is performed by the cutting blade.

According to the insert 5 of the present embodiment, since the rake face 5a is provided with a relatively large rake angle formed in a V-shape, the chips are reliably cut to reduce cutting resistance. And the shape of the insert 5 can be a hexagonal plate.
Moreover, according to the insert 5 of this Embodiment, since the arc-shaped land part 5e was formed, the strength fall of the outer peripheral end of the insert 5 can be prevented.
Furthermore, according to the insert 5 of the present embodiment, the first cutting edge 5c, the second cutting edge 5d, and the land portion 5e have two sets of 180 ° rotational symmetry about the midpoint with the diagonal line in between. Since it is formed, even if one set of cutting blades wears out, it is possible to perform cutting with the other set of cutting blades by rotating the attachment state of the insert 5 to the holder 3 by 180 °.

According to the holder 3 of the present embodiment, the insert 5 can be attached with a simple configuration by providing the attachment region A of the insert 5 having the insert seat surface 3b and the opposing wall surfaces 3c to 3e. The cutting pad can be reliably held on the inner periphery of the workpiece during cutting by the guide pad 7 provided on the outer periphery of the outer peripheral member 3 at intervals in the circumferential direction.
Further, according to the holder 3 of the present embodiment, by providing the adjustment mechanism 6, the attachment position of the insert 5 can be adjusted to obtain a desired machining hole diameter.

And according to the gun drill 1 of this Embodiment which attached the said insert 5 to such a holder 3, the rake face 5a of the insert 5 is provided with the comparatively big rake angle formed in the V shape inclined. Therefore, it is possible to cut the chips reliably and reduce the cutting resistance. The insert 5 and the holder 3 can be detachable with a simple configuration.
Therefore, since only the flat insert seat surface 3b and the opposing wall surfaces 3c to 3e need to be formed on the holder 3, the entire gun drill 1 can be simplified.
Moreover, according to the gun drill 1 of this Embodiment, the attachment position of the insert 5 can be adjusted with the adjustment mechanism 6 provided in the holder 3, and a desired process hole diameter can be obtained.
Further, according to the gun drill 1 of the present embodiment, the insert 5 is provided with the arc-shaped land portion 5e toward the outer periphery of the holder 3, so that the strength of the outer peripheral end of the insert 5 can be prevented from being reduced, and the insert 5 Even if the attachment position of 5 is adjusted, it is possible to reliably avoid contact between the land portion 5e and the work piece by making the diameter (diameter) of the arc formed by the land portion 5e smaller than the diameter of the machining hole. it can.
Further, according to the gun drill 1 of the present embodiment, since the insert 5 is attached to the holder 3 with the back taper angle θ, it is possible to more reliably prevent the land portion 5e from contacting the work piece. Can do.

Further, according to the gun drill 1 of the present embodiment, the four arc-shaped guide pads 7 brazed to the outer periphery of the holder 3 are slidably contacted with the inner surface of the machining hole. Compared with the case where the guide pad is provided over the entire circumference of the holder 3, the sliding contact resistance between the guide pad and the workpiece, that is, the cutting resistance, can be surely held without causing a collapse on the inner circumference. Can be greatly reduced.
Furthermore, according to the gun drill 1 of the present embodiment, since the insert 5 is attached to the holder 3 so as to be a so-called core drop, the central portion of the work piece is left unprocessed. Absent.

  It is possible to provide a gun drill insert, a gun drill holder and an insert type gun drill in which cutting resistance is reduced and the insert and the holder are detachable with a simple structure.

It is a front view of an insert type gun drill of an embodiment of the present invention. It is a principal part enlarged view of the insert type | mold gun drill of embodiment of this invention. FIG. 3 is a view in the direction of an arrow X in FIG. 2. It is a side view of the insert of a Y direction arrow in FIG. It is a side view of the insert of the Z direction arrow in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insert type gun drill 3 Holder 3b Insert seat surface 3c, 3d, 3e Opposite wall surface 5 Insert 5a Rake surface 5b Relief surface 5c 1st cutting blade 5d 2nd cutting blade 5e Land part 6 Adjustment mechanism 7 Guide pad

Claims (3)

A gun drill insert in which a convex V-shaped cutting blade is formed at the intersection ridgeline of the rake face and the flank face of the hexagonal plate-like insert, and is detachably attached to the gun drill holder tip.
The rake face of the insert is formed to be inclined in a V shape with a diagonal line connecting the vertices located on opposite sides of the hexagonal shape,
Two sides of at least one of the three sides of the two hexagons sandwiching the diagonal line are the convex V-shaped cutting blades,
An insert for a gun drill, wherein a land portion having an arcuate cross section perpendicular to the other side is formed on the other side of the three sides of the one set. A holder for a gun drill in which an insert having a hexagonal flat plate shape is detachably attachable and an oil hole extending in the axial direction is formed,
An insert seat surface formed extending from the tip portion in parallel to the axis line at the tip end opposite to the oil hole across the axis, and a plurality of the inserts formed from the insert seat surface. A mounting region of the insert provided with a facing wall formed opposite to the flank of
An adjustment mechanism for adjusting the attachment position of the insert attached to the attachment region;
A plurality of guide pads are provided on the outer periphery of the holder so as to extend in the axial direction at intervals in the circumferential direction, and the outer peripheral surface has an arc shape in a cross section orthogonal to the axis. Holder for gun drill. The gun drill insert according to claim 1 is attached to the gun drill holder according to claim 2 so that the cutting blade protrudes toward the tip of the holder and the land portion is detachably attached toward the outer periphery of the holder. This is an insert type gun drill.

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