JPS5817692Y2 - deep hole drill - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the structure of the cutting edge and tip attachment of a deep hole drill such as a two-sided gun drill.

Conventionally, as a drilling tool for deep hole machining, cutting oil is supplied to the cutting part from a hole that passes through the tool body in the axial direction, and the
A so-called gun drill is known that collects chips together with chips from a shaped groove.

The cutting edge of these tools is formed in a straight line in the radial direction from the center when viewed from the bottom. Therefore, when cutting by rotating the tool, it advances at the same rotational angle phase from the center to the outer periphery, and the chips are removed from the cutting edge. Cutting is done by pressing in the direction of travel.

For this reason, the cutting resistance is relatively large relative to the unit length of the cutting edge, and the drill wears out quickly, which poses a problem in high-speed heavy cutting of steel.

In addition, in recent years, work materials have come to include many difficult-to-cut materials and high-hardness materials, and it has become necessary to use cemented carbide for drills, but in the case of cemented carbide, there are certain When cutting steel at a speed lower than that, there is a problem that the cutting edge may be damaged due to chips or built-up cutting edges being crimped or falling off.

For this reason, when cemented carbide is used for a drill, the cutting speed near the center is slow even if the tool is rotated at high speed, so damage to the cutting edge near the center will impede the drilling ability.

Furthermore, with conventional cutting edge shapes, the chips generated during steel cutting tend to be crimped against the rake face, making it difficult to eject the chips smoothly, and as a result, the feed rate of the drill cannot be increased very much.

In addition, when attaching a tip with a cutting edge to a shank consisting of a hollow shaft, either the entire tip member that is continuous with the shank is made of a cemented carbide tip, or the tip member is made separately and the tip is attached to it. Furthermore, this is connected to the shank in the axial direction.

Therefore, machining the cutting oil hole in the tip member, connecting it to the shank, etc. takes time and effort, leading to an increase in manufacturing costs.

In view of these points, it is an object of the present invention to provide a drill for deep holes with excellent cutting performance of the cutting blade and a simple structure for mounting the tip.

The present invention provides a drilling tool having a means for forcibly supplying cutting oil to the cutting part, in which the shank is formed by forming a pipe into a substantially figure-eight shape so as to form concave grooves on both sides of the cross section. A tip with a cutting edge is attached to the tip of the shank on the rear side of each of the grooves in the direction of rotation, and when viewed from the bottom of the tool, the cutting edge has a starting end located near the center of rotation and a curved line that is convex in the direction of rotation. The cutting edge curve at the center has a larger curvature than the cutting edge curve at the outer periphery.

Hereinafter, the present invention will be explained with reference to drawings of embodiments.

1 is the shank, 2 is the driver that attaches to the machine, 3
is a tip with a cutting edge, and the shank 1 is formed by molding a pipe into a substantially figure-eight cross-sectional shape, with a concave groove 5 formed on both sides and a pair of substantially fan-shaped holes 4. There is.

The groove shape is, for example, a square square shape with an opening angle θ of about 110°.

Further, an appropriate number of guide pads 6 are arranged on the outer periphery of the tip of the shank 1.

The holes 4 are circular at the base of the shank 1 and communicate with the holes 40 of the driver 2, and at the tip of the shank 1, independent holes 4 are opened as shown in FIG.

Cutting oil is supplied to the cutting section through the holes 40, 4.

The tip 3 is attached to the rear side of the ■-shaped groove 5 in the rotational direction at the tip of the shank 1 by brazing or other means.

When viewed from the bottom, the cutting edge 8 is as shown in FIG.
The cutting edge has its starting end 1 near the center of rotation, forms a convex curve in the direction of rotation, and is configured such that the cutting edge curve at the center has a larger curvature than the cutting edge curve at the outer periphery.

When drilling is performed with this drill, the notch in the workpiece starts from the center point, and the chips gradually move toward the outer periphery and at the same time move in the opposite rotational direction in the phase of the rotational angle direction.

That is, since the cutting edge is spiral, the chips move toward the outer circumference as the drill rotates.

In conventional tools, the cutting edge is formed radially and linearly from the center point, so the cutting edge always advances in the same rotational direction phase from the center to the outer periphery, and the start of cut at each point on the cutting edge is the same. The cutting is done simultaneously in the rotational direction phase, and the cutting resistance is large because the chips are pushed almost perpendicularly to the cutting blade in the direction in which the cutting blade advances, so the chips are crimped onto the cutting edge and prevent smooth cutting. It had become.

However, in the above configuration, since the cutting blade 8 is inclined with respect to the direction of movement thereof, the chips are successively pushed out in the outer circumferential direction.Therefore, the cutting resistance is small, and the chips are also not crimped onto the cutting blade. Because there is no oil, it is ejected smoothly and cutting is done well.

Furthermore, because the spiral shape of the cutting blade has a large curvature near the center point, the cutting is performed reliably despite the slow cutting speed of the cutting blade, which causes upward slip as with conventional products. Good cutting is performed without any problems.

In addition, due to these characteristics, it has become possible to use cemented carbide in deep hole drills with a center portion as the tip in the axial direction.

In other words, in the conventional cutting blade shape, if the center part is the tip in the axial direction, cemented carbide could not be used because chipping tends to occur near the center part where the cutting speed of the cutting blade is slow, but in the above configuration, the center part is the tip. Since the cutting resistance is small near the part and the cutting chips are sequentially sent out toward the outer circumference to ensure good cutting, chipping will not occur even if cemented carbide is used.

Moreover, by using cemented carbide, it is possible to cut difficult-to-cut materials and high-hardness materials, and because the machinability is also good, it is now possible to efficiently process conventional drills at high feed rates. .

Another feature of this rectangular shape is that in the case of conventional rectangular shapes, the cutting edge is straight, so the cutting force that tries to bend the elongated drill is concentrated in a relatively narrow direction; Since the particles are dispersed in multiple directions, this is advantageous in terms of the strength of the drill, making it possible to perform relatively high-feed cutting.

Chips generated during machining are discharged to the outside through the ■-shaped groove 5 together with the cutting oil supplied from the hole 4.

In addition, because the present invention uses a tip that is almost plate-shaped and has a rectangular cross section with a portion of the tip formed as a curved surface, it is possible to attach it directly to the shank as described above, unlike the conventional method. When using a substantially plate-shaped tip with a cutting edge formed only within the plane of the rake, the tip will be positioned as shown by the imaginary line 30 in Figure 2, and will not be supported by a normal pipe. becomes weaker.

Therefore, by using a moon-shaped tip as in the present invention, it becomes possible to firmly attach a plate-shaped tip to a normal shank for the first time, and the structure becomes simple, as well as the above-mentioned characteristics of the spiral cutting edge. This makes it possible to obtain a deep hole drill with excellent cutting performance.

[Brief Description of the Drawings] Fig. 1 is a partially cutaway side view showing an embodiment of the present invention;
The figure is a bottom view, FIG. 3 is a right side view of FIG. 1, and FIG. 4 is a sectional view of the shank base. 1...Shank, 3...Tip, 4.
... Hole, 5 ... Concave groove, 8 ... Cutting edge.

Claims (1)

[Scope of utility model registration request] In a drilling tool having a means for forcibly supplying cutting oil to the cutting part, the shank is formed by forming a pipe into an approximately figure 8 shape so as to form concave grooves on both sides of the cross section, and the tip of the shank. A chip having a cutting edge at the bottom is attached to the rear side of each of the grooves in the direction of rotation, and each of the cutting edges has a starting end located near the center of rotation, and forms a curve convex in the direction of rotation when viewed from the bottom of the tool. A deep hole drill characterized in that the cutting edge curve at the center has a larger curvature than the cutting edge curve at the outer periphery.