JPH0357378Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a throw-away type drill that can be applied to drilling large diameter holes, for example, drilling holes of about 55 ψ to 120 ψ mm.

(Prior Art) Conventionally, as a throw-away type drilling tool, for example, Japanese Utility Model Publication No. 60-37215, U.S. Patent No.
4194862 and the like are disclosed.

The former was filed by the applicant and relates to a bowling head. This boring head incorporates a throw-away tip consisting of a hexagonal plate and a square plate, which provides a particularly good balance of cutting forces.
On the other hand, the latter relates to a throw-away type drill, and the throw-away tip includes a circular plate and a square plate having a notch.

(Problem that the invention aims to solve) However, with the former tool, chips from the workpiece are discharged backwards along with cutting oil from a through hole in the tool body, so special cutting oil supply equipment is required. It is necessary.

On the other hand, the latter tool can be applied as long as there is a simple cutting oil supply facility. However, in a throw-away type drill, it is important to balance the bite during cutting and the cutting force, and the drill shown in the above-mentioned US patent did not have good biting properties because it had a circular plate throw-away tip. Therefore, with this type of indexable drill,
The blade shape is designed so that it can be applied to large-diameter hole machining.
Improvements such as the configuration of the injection holes are an issue.

For this reason, the present invention basically adopts the blade shape configuration of the boring head described above, sets a range suitable for throw-away type drills, and takes into consideration the cutting oil injection hole configuration. This is an attempt to solve the above problems.

(Means for Improving the Problems) The present invention was devised in view of the above-mentioned points, and a pair of flute grooves are formed in the axial direction on the outer peripheral portion of the tool body having a rod shape. A cutting oil supply hole is drilled in the axial direction along the axis center line of the main body, and at the tip of the flute groove, a center cutter is formed from near the axis center toward the outer circumference based on the diameter direction. , a throw-away tip consisting of one or more intermediate blades and a peripheral blade is arranged and fixed, and the cutting edges of the central blade, intermediate blade, and peripheral blade are arranged diametrically so that they partially overlap on the rotation locus. The present invention provides an improved throw-away drill having an offset.

That is, near the tip of the tool body, the supply hole is divided into two parts from the center of the shaft, and a first injection hole is formed that opens approximately at the center of the land portion of the tool body. Further, from the intermediate part of the first injection hole, a second injection hole is branched from the upright wall of the flute groove toward the center blade and the intermediate blade and outer peripheral blade in the flute groove on the opposite side of the central blade. An injection hole is formed, which improves the supply of cutting oil.

Further, the center blade has a hexagonal plate shape in which the apex corners of an equilateral triangular plate are equally beveled so that cutting corners are formed by the beveled corners. When this center blade is installed in the flute groove of the tool body, the cutting corner constitutes the cutting edge starting point, and this cutting starting point is offset by 2 to 3 mm with respect to the axial center line of the tool body. The cutting edge ridge extending from the axial center side of the tool body toward the outer circumferential side forms a relief angle α with respect to the diametrical line of the tool body.

Furthermore, the intermediate blade and the peripheral blade each have a substantially square plate shape. and,
The cutting edge of these intermediate and peripheral cutting edges from the shaft center side to the outer circumferential side forms a clearance angle β with the diametrical line of the tool body, and this clearance angle β is within the range of 3° to 7°. is set smaller than the relief angle α. Further, on the rotation locus of these intermediate blades and peripheral blades, the step amount δ formed between the cutting edge ridges is set to 0.15 to 0.35 mm.

(Function) In the indexable drill of the present invention, leading cutting is performed by the center cutting edge that is offset from the axis center line of the tool body, and then cutting is performed by the intermediate cutting edge and the outer cutting edge in that order. . The cutting edges formed on the intermediate cutting edge and the peripheral cutting edge each form a clearance angle of β=3° to 7° with respect to the diametrical line, as seen in the above-mentioned Japanese Utility Model Publication No. 60-37215. By reducing the relief angle β relative to the object, cutting can be performed quickly. This is because a pair of flute grooves are formed in the axial direction on the outer peripheral portion of the tool body, so the tool rigidity is not so high.

In addition, a step amount δ is formed between the cutting edge ridges formed on the intermediate cutting edge and the outer peripheral cutting edge, and this step amount δ is also reduced to 0.15 to 0.35 mm to address the tool rigidity problem mentioned above. are doing.

Furthermore, the throw-away drill of this invention is
Sufficient cutting oil is supplied to the center, intermediate, and peripheral edges to ensure good cutting. Therefore, at the tip of the tool body,
A first injection hole is formed in the land portion, and a second injection hole is formed in the upright wall of the flute groove, thereby providing an effective cutting oil supply function.

(Example) Hereinafter, an example of the indexable drill of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a rod-shaped tool body, and a shank portion 2 is formed at the rear end. A pair of flute grooves 3a and 3b are formed in the axial direction on the outer circumference of the tool body 1, and a supply hole for supplying cutting oil is formed in the axial direction along the axial center line of the tool body 1. 4 is drilled. In this case, the supply hole 4 is connected to the tool body 1
Near the tip of the tool body 1, it is divided into two parts from the center of the shaft, and first injection holes 6, 6 open toward the approximate center of the land parts 5, 5 of the tool body 1.

Further, second injection holes 8a, 8b are provided from intermediate portions of the first injection holes 6, 6 toward the upright walls 7a, 7b of the flute grooves 3a, 3b, respectively.

A chip seat 9 is provided at the tip of the flute grooves 3a, 3b formed in the tool body 1, and a chip seat 9 is provided in the chip seat 9 from near the shaft center to the outer circumferential side with reference to the diametrical direction. Then, the center blade 10,
A throw-away tip consisting of one or more intermediate blades 11 and outer peripheral blades 12 is arranged and fixed.
In this case, the center blade 10, the intermediate blade 11, and the outer peripheral blade 12 are attached using the center attachment hole 13 using, for example, a set screw 14.

Note that the opening direction of the upright walls 7a, 7b of the second injection holes 8a, 8b mentioned above is on the one hand,
0, and on the other hand, toward the intermediate blade 11 and the outer peripheral blade 12 located in the flute groove 3b on the opposite side from the central blade 10, thereby smoothing the supply of cutting oil. Therefore, the thermal influence on the center blade 10, intermediate blade 11, and outer peripheral blade 12 during cutting is alleviated.

In addition, in order to improve the biting property on the workpiece material, the center blade 10 has an equilateral triangular plate whose apex portions are equally beveled, and cutting corners 15 are formed by the beveled corners. It has a hexagonal plate shape. When installed in the tip seat 9 of the flute groove 3a of the tool body 1, the cutting corner 15 constitutes a cutting starting point. This cutting starting point is the tool body 1
It has a deviation amount A with respect to the axis center line. In this case, the amount of deviation A varies depending on the outer diameter of the cutting edge of the drill, but is usually set within a range of 2 to 3 mm. Further, a cutting edge 16 extending from the shaft center side toward the outer periphery of the center blade 10 forms a relief angle α with respect to the diametrical line of the tool body 1. This clearance angle α is normally set as a constant value of A=15° due to the biting property of the cutting edge.

Furthermore, the intermediate blade 11 and the outer peripheral blade 12 are
Each of them is a substantially square plate. The intermediate blade 11 and the outer peripheral blade 12 are
As shown by the rotation locus in the figure, the cutting edge edges 17 and 18 from the shaft center side to the outer circumferential side are aligned with the tool body 1.
A relief angle β is formed with respect to the diametrical line, and a step amount δ is formed. In this case, the clearance angle β is
It is smaller than the relief angle α of the center blade 10, and specifically, β is set within the range of 3° to 7°. In addition, the step amount δ is set to a value larger than the feed amount per rotation, and varies depending on the outer diameter of the cutting edge, but is 0.15 to 0.35.
Set within the range of mm. The reason why such a step amount was added is that the intermediate blade 1 was added as shown in Fig. 4.
This is because four cutting edge ridges 16 and 17 are used in the cutting edge 1 and the outer peripheral edge 12.

Further, the clearance angle β and the step amount δ set in this manner are set to smaller values than those found in the above-mentioned Japanese Utility Model Publication No. 37215/1983. That is, in the above-mentioned publication, the relief angle β is set to 10° and the step amount is set to 0.4 mm. In the indexable drill of the present invention, there are a pair of flute grooves 3 in the axial direction of the tool body 1.
This is because the rigidity of the tool body 1 is not so high because the tool body 1 is formed with the shapes a and 3b. Therefore, the intermediate blade 11 and the peripheral blade 12 reduce the clearance angle β to start cutting the workpiece earlier, and also reduce the cutting edge 17, which is related to the feed amount per rotation.
The amount of step difference δ of No. 18 is reduced to reduce the burden of cutting resistance.

In addition, the center blade 10, the intermediate blade 11, and the peripheral blade 1
Appropriate chip breaker grooves (not shown) can be formed along the two cutting edge edges 16, 17, and 18. Furthermore, these center blade 10, intermediate blade 1
1 and the peripheral blade 12 are usually made of cemented carbide, but their surfaces may be provided with a single or multiple coating layer of TiC, TiN, Al ₂ O ₃ or the like.

Next, examples of tool specifications and cutting examples for the indexable drill of the present invention will be explained.

That is, the tool specifications are roughly shown in Figures 1 and 2, with the outer diameter of the cutting edge being 90 mm.
mm, for the center blade 10, the inscribed circle diameter is 12.7 mm
An equilateral triangular plate with the apex portion beveled at an angle of 30° was applied. Further, for the intermediate blade 11 and the outer peripheral blade 12, a 12.7 mm throwaway tip was used. These center blade 10, intermediate blade 11, and outer peripheral blade 12 are inserted into the tip seat 9 of the flute grooves 3a, 3b of the tool body 1 by a set screw 14.
It was fixed by In this case, the deviation amount A of the center blade 10 = 3 mm, the clearance angle α = 15°, the clearance angle β of the cutting edge ridges 17 and 18 in the intermediate blade 11 and the peripheral blade 12 =
It was set to 5° and the step amount δ = 0.2 mm.

In addition, the outer edge of the cutting edge 16 of the center blade 10 is set to be 33.43 mm on the rotation trajectory, and the outer edge of the cutting edge 16 of the intermediate blade 11 and the peripheral blade 12 is set to 33.43 mm.
For the outer edges in 7 and 18, respectively
It was set to be 45.58mm, 67.79mm, and 90.0mm.

On the other hand, in the cutting example, an S58C block (length 150 mm x width 100 mm x height 60 mm) was cut through in the height direction using an indexable drill with an outer diameter of the cutting edge of 75 mm.

The cutting conditions at this time were: rotation speed = 430 rpm, cutting speed = 100 m/min, feed per revolution 0.1 mm/rev,
Feed per minute = 43mm/min, water-soluble cutting oil
It was supplied at Kg/cm ² ×10/min (hydraulic pressure x oil amount).

As a result, the vibration state during cutting was good, with no abnormal vibrations, including during biting and during pull-out. In addition, regarding the state of chip discharge, there were many cutting type chips, and the chip discharge was good.

Furthermore, the thrust load during cutting is 700~800Kg.
It was confirmed that the amount of damage was significantly reduced compared to ordinary twist drills. This is due to the biting property due to the blade shape configuration and the cutting force balance effect described below.

(Effects) The throw-away drill of the present invention constructed in this way has the improved configuration of the cutting oil injection hole in the blade shape, and has the following effects.

First, it is suitable for drilling large diameter holes, for example, holes of about 50 to 120 mm. This is due to the arrangement and numerical limitations of the central blade 10, intermediate blade 11, and peripheral blade 12, and the sufficient supply structure for cutting oil. That is, the center cutting edge 10 has good biting properties, and the relief angle β and the step amount δ allow the intermediate cutting edge 11 and the peripheral cutting edge 12 to start cutting earlier, thereby creating a stable cutting condition. The cutting forces applied to the cutting edges 16, 17, and 18 are all directed in a direction substantially close to the axial center line of the tool body 1 in the vertical direction, and cancel each other out in the diametrical direction. It's because I'm old.

Second, the tool type is simplified and efficiency can be expected to be improved. This is because the format of the conventional twist drill can be almost followed. In addition, high-speed cutting and high feed are possible due to the above-mentioned biting properties and balance of cutting force.

[Brief explanation of the drawing]

FIG. 1 is a front view showing an embodiment of the indexable drill according to the present invention, FIG. 2 is a bottom view thereof, and FIG. 3 is an explanatory diagram showing rotation loci of the center cutting edge, intermediate cutting edge, and peripheral cutting edge. FIG. 4 is an enlarged perspective view showing how the cutting edges of the intermediate blade and the peripheral blade are used. 1... Tool body, 3a, 3b... Flute groove,
4... Supply hole, 5... Land portion, 6... First injection hole, 7a, 7b... Standing wall, 8a, 8b...
2nd injection hole, 10...center blade, 11...middle blade, 12...outer peripheral blade, 15...cutting corner, 16, 17, 18...cutting edge ridge.

Claims (1)

[Claims for Utility Model Registration] A pair of flute grooves 3a and 3b are formed in the axial direction on the outer peripheral portion of the tool body 1 having a rod shape, and a pair of flute grooves 3a and 3b are formed in the axial direction along the axial center line of the tool body 1. A cutting oil supply hole 4 is drilled, and at the tips of the flute grooves 3a and 3b, a center blade 1 is formed from near the shaft center toward the outer circumferential side based on the diametrical direction.
0, 1 or 2 or more intermediate blades 11 and peripheral blades 1
In the indexable drill, two throwaway tips are arranged and fixed, and the center cutter 10, intermediate cutter 11, and outer peripheral cutter 12 are offset in the diametrical direction so as to partially overlap on the rotation locus. The hole 4 is located near the tip of the tool body 1.
A first injection hole 6 that is divided into two parts from the center of the shaft and opens approximately at the center of the land portion 5 of the tool body 1;
6 is formed, and this first injection hole 6,
The flute grooves 3a, 6 are formed in a direction from the intermediate part of the blade 6 toward the center blade 10 on the one hand, and toward the intermediate blade 11 and the outer peripheral blade 12 in the flute groove 3b on the opposite side to the center blade 10 on the other hand. A second injection hole 8 branched into the standing walls 7a and 7b of 3b.
a, 8b, and the central blade 10 is a hexagonal plate in which the apex portions of an equilateral triangular plate are equally beveled so that cutting corners 15 are formed by the beveled corners. The flute groove 3 of the tool body 1
When the cutting corner 15 is installed in the tool body 1, the cutting corner 15 constitutes the starting point of the cutting edge, and this cutting starting point is
The cutting edge 16 has a deviation amount A of 2 to 3 mm, and the cutting edge 16 extending from the axial center side of the tool body 1 to the outer peripheral side forms a clearance angle α with respect to the diametrical line of the tool body 1. The intermediate blade 11 and the peripheral blade 12 each have a substantially square plate shape, and the cutting edge ridges 17 and 18 extending from the shaft center side to the outer peripheral side have a clearance angle β with respect to the diametrical line of the tool body 1. is formed, and this relief angle β is
It is set smaller than the relief angle α within the range of 3° to 7°, and on the rotation trajectory, the cutting edge ridges 17, 1
A throw-away type drill characterized in that the step amount δ formed between the 8 holes is set to 0.15 to 0.35 mm.