JPS59187406A - Throwaway tip drill - Google Patents

Abstract

PURPOSE:To perform the boring of a small diameter with high precision by overlapping two throwaway tips and removably fixing them. CONSTITUTION:A throwaway tip 12 consisting of two circular tips is arranged against a drill axis. Accordingly, the balance cut generating a cutting force in axial symmetry is made available. The curvature of the drill is decreased and the boring with high precision can be performed. In addition, the locus of a cutting edge 26 at the center of the drill becomes nearly a conical shape, thereby is centripetal, and also from this standpoint the boremachining of a small diameter can be performed with high precision while using a tip with a comparatively large size.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an indexable tip drill having an indexable tip removably fixed to a drill body.

Demand for this type of drill has increased dramatically in recent years because it can perform drilling work with high efficiency and is relatively low cost, but due to its structure, small size drills are advantageous. <<, for example using a commercially available tip with a diameter of 161II
It was considered difficult to manufacture a drill with a diameter less than I.

Against this background, the present invention has been made with the object of providing an indexable tip trill that can perform small diameter hole &-1 machining while using a relatively large tip.

The gist of the present invention is to overlap two circular indexable inserts so that the surfaces on which cutting edges are formed on the outer periphery are partially in contact with or close to each other and face each other. It is removably fixed to the tip of the drill body in an axial state, axially symmetrical with respect to the axis of the drill body.

By making a 21 yen indexable tip into an over-harvest in this way, the drill diameter can be made smaller even though the tip itself is large. Conventionally, triangular, square, or rhombic tips have been used as throw 7-way tip tips for drills, but since it is necessary to restrain the Q sides when fixing these to the drill body, such tips have not been used. Due to the circumstances of machining the chip mounting seat, it was impossible to make the two thousand knobs overlapping.
The circular indexable tip can be fixed to the drill body by positioning it with an arc-shaped restraining surface. Because it is easy to do so, it is possible to overlap and fix two tips, and a small diameter drill can be obtained while using a relatively large tip.Moreover, it is possible to obtain a drill with a small diameter while using a relatively large tip. In this system, one thousand-knob cut the center of the hole, and the other tip cut the outer periphery, so the cutting force was not generated axially symmetrically, causing the drill to curve and reducing machining accuracy. However, in the drill according to the present invention, the two indexable tips are arranged symmetrically with respect to the axis of the drill, so the cutting force is generated axially symmetrically, which is a so-called balanced cut. This makes it possible to reduce the curvature of the drill.
This allows for highly accurate drilling. Moreover,
The trajectory of the cutting edge at the center of the drill has a nearly conical shape, so it has centripetal properties, and from this point as well, improvement in machining accuracy can be expected.

An embodiment of the present invention will be described below with reference to the drawings.

The drill (not shown in FIGS. 1 to 3) consists of a drill body 10 and two circular tips 12. The trill main body 10 has a large diameter shank 14 and a small diameter tenon 16, and two circular tips 12 are attached to the tip of the body 16 to attach the bolt 1.
8, the drill is removably fixed.

More specifically, two straight chip discharge grooves 20 are formed from the tip side of the body 16 axially symmetrically with respect to the Φ+b center of the drill, and an arc-shaped restraint is formed at the tip end of these grooves 20. Two knob mounting seats 24 are formed on the side of the surface 22. The restraining surface 22 of the chip mounting seat 24 is exactly a conical surface. is fixed in close contact with the restraining surface 22. When the thousand knob 12 is fixed, the surface 28 on the side where the cutting edge 26 is formed on the outer periphery is in almost contact with the outer peripheral edge, as shown in FIG. The drill diameter is smaller than twice the diameter d of the large diameter side of the tip 12.The tip 12 is axially aligned with respect to the axis of the drill body 10. It is arranged symmetrically, and 2
The cutting edges 26 of the tips 12 are arranged to intersect on the axis of the drill body 10. Further, as is clear from FIG. 1, the land 30 of the body 16 has a tip end surface formed into a spherical surface 32 so as to be located inside the locus drawn by the two tips 12 when the drill is rotated around its axis. In addition, the portion continuous to a20 is chamfered to form a slope 34.

A dead-end hole 36 is formed in the shank 14 of the drill body 10, and two oil supply holes 38 extend from the bottom of the dead-end hole 36 as shown in FIG.
6 and is opened at the slope 34.

When drilling with a drill constructed as described above, the drill can be rotated around its axis while supplying a cutting curve from the oil supply hole 38, and pressed against the workpiece.
cuts the workpiece to first form an annular groove.

Furthermore, when the trill is advanced, the intersection of the cutting blades 26 of the tip 12 comes into contact with the workpiece, and then the outermost periphery of the cutting blades 26 comes into contact with the workpiece, and cutting becomes a constant current state. Transition. Chips cut by the cutting blade 26 flow on the surface of the chip 12 and are discharged from the groove 20 to the outside, but the head of the bolt 18 for fixing the chip 12 is completely inside the chip 12. Because it is embedded, it does not obstruct the flow of chips.

Further, the slope 34 formed on the land 30 allows chips cut by the drill center portion of the cutting blade 26 to smoothly flow toward the groove 20.

In the drill of this example, the tip 12 is straight 1 IQmm.
If you use a tip with a diameter of 18 to 19.5 mm, you can drill a hole with a diameter of 18 to 19.5 mm.
Capable of drilling holes of 4 to 15.5 man.

Although one embodiment of the present invention has been described in detail above, the present invention includes other embodiments in which various changes are made to the means for fixing the tip to the drill body, the shape of the drill body, etc. based on the knowledge of those skilled in the art. Of course, it can be implemented with

[Brief explanation of the drawing]

FIG. 1 is a front view of an indexable tip drill according to an embodiment of the present invention, and FIGS. 2 and 3 are a bottom view and a side view, respectively. 10 Nitrile body 12: Circular tip 18: Bolt
20: Groove 22; Restricting surface 24: Chip mounting seat 26: Cutting blade
28: Applicant: Fuji Seiko Co., Ltd.; Figure 3 212

Claims (1)

[Claims] Attach the circular indexable tip 2IIIii to the tip of the drill body in an overlapping state so that the surfaces on which the cutting edge is formed on the outer periphery are partially in contact with or close to each other and face each other. A throw-away tip drill characterized by being fixed axially symmetrically and removably with respect to the axis.