JPS5943046Y2 - chiselless thinning drill - Google Patents

Description

[Detailed description of the invention] The present invention relates to a chisel-less thinning drill, and in particular, the chisel is a 5K chisel that eliminates the chisel part in the cutting edge located at the tip of the drill to improve the drilling force and the thread characteristics. This is about less thinning drills.

In general, the cutting edge of a twist drill includes a main cutting edge 1, a circumferential edge 2, and a tip slope s, as shown in FIGS. 1 and 2.
A suitable place called a chisel portion 5 without a flat cutting edge is provided at the position where 3 and 4 intersect.

When using a twist drill, the chisel part 5 scoops out the rigid material, spreads it out, pushes it out from the center to both sides, and the workpiece is pushed out from the chisel part 5 to the outside. The hole is drilled by scraping off the raised part with the main cutting edge 1 of the drill.

However, because the chisel part 5, which is not provided with a cutting edge, is forced into the workpiece, the chisel part 5
The thrust force exerted on the workpiece is extremely large.

That is, if this is expressed in a graph, it becomes 5 as shown in FIG.

The thrust force of the cutting edge is small at the outer periphery and increases as it moves toward the center chisel section 5 (the closer the cutting edge of the drill is to the chisel section 5, the more negative its effective rake angle becomes, and the more the effective clearance angle becomes ), the chisel portion 50 suddenly becomes larger.

Therefore, by thinning the chisel part 50
It is generally well known that reducing the width of the chisel portion 5 has the effect of reducing the thrust force against the rigid material.
There is a limit to reducing the zero width, and it was thought that zero KFi could not be achieved.

However, no matter how small the chisel portion 5 is, as long as it remains, the generation of thrust force from the chisel portion 5 cannot be avoided, and the ratio of generation from the chisel portion 5 to the total thrust force may reach 50 ToK. .

This invention aims to significantly reduce the thrust force by reconsidering the conventional concept of leaving the chisel part and completely removing the chisel part.By reducing this thrust force, machining efficiency can be improved and tool The purpose of this invention is to provide a chisel-less thinning drill with features such as improved life and hole accuracy.

In order to achieve such an objective, the present invention has a pair of main cutting edges formed at the end positions of the tip slope in the rotational direction, and a chip pocket formed by thinning a predetermined portion of the tip slope. a auxiliary cutting edge formed in the center portion of the drill by m-thinning and having a substantially crank-like shape in plan view to connect the pair of main cutting edges; and a auxiliary cutting edge formed on the outer peripheral side of the tip slope portion. The cutting edge portion includes a circumference formed along the helical groove and a circumference formed along the twisted groove.

The details of the present invention will be explained below using examples shown in the figures.

Fig. 4 is a plan view of the cutting edge of the chisel-less thinning drill according to the present invention, Fig. 5 is a front view of the cutting edge, and Fig. 6 is a thrust force distribution diagram during drilling with the chisel-less thinning drill of the present invention. be.

Rotation direction (direction of arrow A) end position K of tip slope parts 6, 7
d. Main cutting edges 8, 9 are formed, and a part of the outer periphery of the tip slope portions 6, 7 is formed along the Kd helical groove 10Vc, and serves as a guide 3 and a belt-shaped hole that oozes out the hole when the drilling force is high. A circumference 11 is provided.

Since the configurations above 11 are the same as those of the prior art, further detailed explanation will be omitted.

However, the feature of the present invention is that the part corresponding to the conventional chisel part is eliminated from such a drill.

That is, to explain this in more detail, the tip slope portion 6
, 7, that is, the portion on the side where the main cutting edges 8, 9 are not provided (the shaded portion in FIG. 4) is thinned to form the chip pocket 12. are doing.

This chip pocket 12 is formed so that a part thereof (the part surrounded by the dotted line B in FIG. 4KB) intersects with the other chip pocket at the center of the drill. A minor cutting edge 13.14 is provided at the intersection point.

That is, the auxiliary cutting edges 13 and 14 are provided on the side and bottom surfaces of the recessed part at the central position of the drill bit shown in FIG. As shown in the figure, the main cutting edges d and 9 are connected to form a crank-like shape.

In this invention, the chisel part that was provided in the center of the drill is removed, and the auxiliary cutting edges 13 and 14 are provided in the part where the chisel part was provided, so that there is no risk of injury when using the drill. First, the main cutting edges 8 and 9 and the auxiliary cutting edge 13 proceed to drill a hole in the workpiece, and the central part of the machined hole is destroyed before receiving the cutting thrust force from the other auxiliary cutting edge 14. .

Therefore, in the drill of the present invention, no thrust force is generated at the center of the drill as shown in FIG.

As explained above, according to the chisel-less thinning drill according to the present invention, the main cutting edge is formed by thinning a pair of main cutting edges formed at the end positions of the tip slope portion in the rotational direction and a predetermined portion of the tip slope portion. a chip pocket formed at the center of the drill by the thinning, and a minor cutting edge formed in a substantially crank shape in plan view to connect the pair of main cutting edges; By having a configuration including a minor cutting edge consisting of a circumference formed along a helical groove and a circumference formed along a helical groove,
It has various effects such as:

That is, (1) Same as above for machining capacity (feed can be increased by an amount commensurate with thrust force resistance).

(2) Reduction of cutting power.

(3) Improved tool life (drill rotation speed can be lowered at constant rate).

(4) It is possible to downgrade the drill (the rigidity of the drill can be lowered only in areas commensurate with the reduction in thrust force).

(5) A low-rigidity machine can be used for drilling.

(6) Improved hole machining accuracy.

(7) Possible to unify the shape when re-grinding the drill. (8) Variations in drill performance due to variations in grinding can be reduced.

[Brief explanation of the drawing]

Figure 1 is a plan view of the cutting edge of a conventional thinning drill, Figure 2 is a plan view of the cutting edge, Figure 3 is a diagram of thrust force distribution during drilling with a conventional thinning drill, and Figure 4 is a diagram of the thrust force distribution during drilling with a conventional thinning drill. FIG. 5 is a plan view of the cutting edge of the chisel-less thinning drill according to the invention, FIG. 5 is a front view of the cutting edge, and FIG. 6 is a thrust force distribution diagram during drilling by the chisel-less thinning drill of the invention. 6.7...Tip slope, 8,9...Main cutting edge, 10...Twisted groove, 11...Circumference, 12... ...chip pocket), 13.14...
...Secondary cutting edge.

Claims (1)

[Scope of utility model registration request] a pair of main cutting edges formed at the end positions in the rotational direction of the tip slope portion; a chip pocket formed by thinning a predetermined portion of the tip slope portion; and a chip pocket recessed in the center portion of the drill by the thinning; and a auxiliary cutting edge formed in a substantially crank shape in plan view so as to connect the pair of main cutting edges, and a circumferential edge provided on the outer periphery of the tip slope portion and formed along a helical groove. A chisel-less thinning drill featuring a cutting edge made up of.