JPS60167707A - Hole processing tool - Google Patents

Abstract

PURPOSE:To increase strength and rigidity of drill by making cross sectional area of a chip groove on a place far from a cutting edge and changing the cross section of the groove rationally. CONSTITUTION:A portion of a chip groove near a cutting edge is made straight and a portion of the chip groove near a shank 3 is made a twisted curved face. The cutting edge, the chip groove following the cutting edge and the chip groove near the shank 3 and the said groove are constructed so that the chip groove near the shank 3 is composed of twisted curved faces 15'-19' and 25'-29' whose depth in the radius direction are short. The cross sectional are of the chip groove is small in the part near the shank, but it is sufficient to remove chips, and the sectional coefficient and secondary moment are large, then strength and rigidity are increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shape of a chip groove of a hole machining tool having a cutting edge at the end of a tool rotating shaft, and its purpose is to improve strength and rigidity while ensuring removal of chips. The goal is to obtain a large hole machining tool.

The above-mentioned hole processing tools include twist drills, carbide drills using cemented carbide tips, and drill reamers that combine a drill reamer and reamer.
There is a problem with rigidity.

Generally, a drill must have a groove (chip 4, groove) in the tool body for removing chips, but since a part of the chip groove must be outside the hole during hole drilling, it is necessary to install a groove in the axial direction of the chip groove. The length of the hole must be greater than the depth of the hole to be machined. Although the chip groove reduces the strong friction and rigidity of the trill,
In particular, drills used to drill deep holes have a significant drop in strength and rigidity, and are prone to breakage, deflection, chatter, etc. It has been attempted to increase strength and rigidity by giving a certain taper to the groove bottom and making the groove bottom thicker, such as #1 near the shank, but the extent of this is small and the effect is not sufficient.

Conventionally, the cross-sectional area of the chip groove is kept approximately constant, but even though a large cross-sectional area is required for cutting near the cutting edge, the cross-section of the generated chips is small, so even if chip twist is taken into consideration, cutting is difficult. The cross-sectional area of the chip groove should be small at a location away from the blade. Focusing on this point, the present invention aims to increase the strength and rigidity of the drill by rationally changing the cross section of the chip groove.

First, as an example, a case where the present invention is fully applied to a straight groove drill having a cutting edge according to Patent Application No. 58-1404-89 will be described.

Figures 1 to 5 show an example in which the present invention is applied to patent application No. 58-T4O4S9 "Rotary cutting tool", Figure 1 is a plan view, Figure 2 is a front view, and the cored blade I is a drill. A right cutting blade 101 having a cutting edge at the rotation center O of the tip. Cutting edge missing part 1
1. and a peripheral cutting edge 102, and the coreless blade 2 has a central cutting edge missing portion 21. Intermediate cutting edge 201. Intermediate cutting edge missing part 2
2° and an outer peripheral cutting edge 202. The wall surface of the chip groove 10 with respect to the cored blade 1 is shown in FIGS.
As shown in the figure, an axis-parallel plane 17-18-19 that continues to the rake face for the cored blade 1, and a bent surface 13-14-15 perpendicular to this (13 and 15 are parallel to the tool rotation axis)
It consists of Here between 13td At B1, 14uB
10. It is assumed that there is a relationship 'Xs>C14>C15 between the depth C13C14'15 of each part of the curved surface from the outer periphery of the tool body. The wall surface of the chip groove 2° for the non-centered blade 2 is perpendicular to the axis-parallel plane 27-28-29 that continues to the rake face for the non-centered blade 2, as shown in FIGS. It consists of rotation curved surfaces 23-24-25 (23 and 25 are parallel to the tool N rotation axis). Here, 23 is between A2 and B2, 24 is between B2C2, 251 is between dc2 and D2, and there is a relationship of '23 >'24> C25 between the depth of each part of the bent surface from the outer periphery of the tool body C23C24t2B. shall be. Bent surfaces 13-14-'15 and 23-
The shape of 24-25 is appropriately determined in consideration of the flow of chips and the interference of the groove machining tool. Depth t□3 for the part where the wall surface is parallel to the axis. tlB, C23, and C25 each have a constant value, but the depth [
□4. t24 varies depending on the location. As can be clearly seen from the figure, the radial depth and circumferential width of the chip groove are maximum at the X1X1 cross section in Figure 3, and at the X3 cross section in Figure 5.
The section modulus and moment of inertia of the tool are minimum at the X1X□ section, maximum at the X3X3 section, and intermediate at the X2X2 section. The strength and rigidity of the tool as a whole is increased compared to the case of a similar cross section. In this case, tls / ttat2s / (2
A value of 3 must be selected.

In order to facilitate the discharge of chips, the entire or part of the chip groove may be made into a twisted curved surface. When I say "part", the part of the chip groove near the cutting edge is straight.
It is practical to form a portion of the chip groove near the shank 3 into a twisted curved surface. Figures 6 to 8 show this case, and the cutting edge, the chip groove following the cutting edge, and the inclined groove connecting it to the chip groove near the shank 3 are the same as those shown in Figures 1 to 5, and the shank The chip groove close to 3 is formed by twisted curved surfaces 15'-19' and 25'-29' with a shallow depth in the radial direction. Figure 8 shows the twisted groove eMoO part OX3'X
3' section, the chip groove with helical curved surfaces 15'-19' is on the back side in FIG.

Changes in the depth of the ocean floor are not limited to those shown. For example, it is possible to apply Shi's theory of uniform strength to give a parabolic change, but it will be a little more difficult to manufacture.

Figures 9 to 14 show an example in which the present invention is applied to a normal twist drill in which the entire chip groove is a twisted curved surface. Figure 9 is a plan view (the upper shank portion is omitted), and Figure 10 is the cutting edge. Figure 11 is a side view of the part near the cutting edge;
Figure 2 is a KK cross-sectional view of the part (between FG) where the diameter of the virtual circle in contact with the chip groove bottom is the same constant value d1 as the cutting edge, and the chip groove depth is t□, and Figure 14 is the virtual depth in contact with the chip groove bottom. Saha C3,
In Figure 13, the diameter of the virtual circle touching the chip groove is from dl to d3.
In the LL cross-sectional view of the portion where the value d2 changes up to (d2 changes smoothly between OH and near O or HK), if the chip groove depth is expressed by t2, tl>t2:>t3. 30 and 40 are main cutting edges, and a rotating surface 40 shown by a two-dot chain line is an imaginary rotating surface in contact with the bottom of the chip groove.

Although the cross-sectional area of the chip groove near the shank is small, it is sufficient for chip removal and has a large section modulus and moment of inertia, which has the advantage of greatly contributing to increased strength and rigidity. The disadvantage is that the part where the cutting edge can be reground and used as a normal twist drill is reduced between FG and FG, but even the part above G is the same as a normal drill if you are willing to take a large amount of thinning. It can be used for enlarging small diameter holes without special thinning.
Useful as a highly rigid drill.

The present invention is not limited to the above embodiments, and can be applied to any rectangular shape. If the chips are large, providing a nick on the cutting edge will prevent the chips from becoming thinner and will improve discharge.

According to the present invention, in a hole machining tool having a cutting edge at the end of the tool rotating shaft, the strength and rigidity can be increased without impeding chip evacuation even when the hole is long in the axial direction. Therefore, there are advantages such as there is less risk of breakage, less possibility of bending or chattering during machining, improved machining accuracy, and increased productivity by being able to withstand heavy cutting and high-speed cutting.

[Brief explanation of the drawing]

Figures 1 to 5 show an example in which the present invention is applied to a rotary hole machining tool consisting of a cored blade having a cutting edge at the center of rotation at the tip of the tool and a non-centered blade without such a core, and Figure 1 is a plan view. , Fig. 2 is a front view, Figs. 3 to 5 are sectional views perpendicular to the axis at three positions with different radial depths of the chip groove, and Figs. 6 to 8.
The figure shows an example in which the chip groove in the part near the shank of the above tool is configured with a twisted curved surface.
The figure is a front view, FIG. 8 is a cross-sectional view perpendicular to the axis of a portion composed of a twisted curved surface, and FIGS. 9 to 14 show an example in which the present invention is applied to a two-flute twist drill. The figure is a plan view (
(shank part omitted), Figure 10 is a front view, Figure 11 is a side view of the part near the cutting edge, Figures 12 to 14 are axial cross-sectional views at three positions with different chip groove depths, The main symbols used in the figures are as follows. ■・・・・・・Centered blade (core cutting edge 11. Cutting edge missing part 1o
1° and outer peripheral cutting edge 12) 2... Coreless blade (core cutting edge missing part 2o1. intermediate cutting edge 21, intermediate cutting edge missing part 202., and outer peripheral cutting edge 22)
) 10...Chip groove 20 for cored blade 1...
...Chip grooves 17, 18, 19 for the uncentered blade 2...
...Axis-parallel plane (part of the wall surface of the chip groove 10) 27, 28.
(Part of the wall surface of the chip groove 1o) 13, 14.15...Bent surface (part of the wall surface of the chip groove 1o) 23, 24.25...Bent surface (part of the wall surface of the chip groove 2o) Wall surface 1 19'... Twisted curved surface forming a part of the wall surface following the rake surface for the cored blade l (representative of 19) 29'... Wall surface following the rake surface for the uncentered blade 2 Twisted curved surface forming part of the curved surface (number 29) 15'-'...°Twisted curved surface forming part of the curved surface forming the wall surface of the chip groove 10 (number 15) 25'... ... Twisted curved surface (replacement of 25) forming part of the curved surface constituting the wall surface of the chip groove 2o 30, 40... Main cutting edge 5 of the twist drill
0...Virtual rotating surface 300 in contact with the bottom of the chip groove...
...Chip groove 400 for main cutting edge 30K...
・Chip groove for main cutting edge 4o Poetry Doto Saran Masao Kubota N Redemption 13 old missing II round

Claims (1)

[Claims] In a hole machining tool that has a cutting edge at the shaft end of the tool rotating shaft, at least one of the radial depth and circumferential width of the chip groove is closer to the shank than to the shaft end cutting edge. Small value: Chips that have at least a part of the wall surface between the chip groove near the shank and the chip groove near the shaft end cutting edge that forms an inclination different from the wall surfaces of both chip grooves with respect to the rotating shaft. A hole machining tool characterized by being connected by a groove.