JPH0332504A - Boring tool - Google Patents

Abstract

PURPOSE:To obtain a boring tool having a good vibration resistance by setting the sectional area at a sectional view in a direction crossing a shank axis at a neck part larger than the sectional area at a sectional view of a shank. CONSTITUTION:The sectional area of a neck part 12 is set larger than the sectional area of a shank 13, so the rigidity of the side of the shank 13 as the support side becomes lower than the side of the neck part 12 when a boring tool is installed in a machine tool by cantilever support, and the whole structure becomes a soft structure with which different vibrations are likely to be produced corresponding to the mass and rigidity at each part. In this constitution, as the sectional area is larger at the neck part 12 than on the side of the shank to make the mass per unit length of the neck part 12 larger than on the side of the shank 13, vibration becomes uncontinuous at a connection part between these. The vibration produced at a blade tip part 11 corresponding to fluctuation of cutting resistance is not transmitted to the shank 13 uniformly, and vibrations of different phases and frequency numbers are produced with the connection part of the neck part 12 with the shank 13 as the boundary, thereby growth of chattering vibration is prohibited by interference of these vibrations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application! IF] The present invention relates to a boring tool used when machining the inner diameter of a workpiece in turning processing.

[Prior Art] Conventionally, as this type of boring tool, for example, the 21st
As shown in FIGS. 23 to 23 or 24 to 26, a cutting edge portion 2 has a throw-away tip (hereinafter abbreviated as a tip) l attached to one side of the tip;
A cylindrical neck portion 3 formed on the base end side of this cutting edge portion 2;
A substantially cylindrical shank 4 formed on the base end side of this neck portion 3
It is known that it is roughly constructed from the following.

Here, the chip l has a substantially rhombic shape in plan view,
One of the cutting edges 5 formed at the two opposing corners is detachably attached to the cutting edge part 2 in a state of protruding from the tip and outer periphery of the cutting edge part 2.

Further, the diameter d of the neck portion 3 is set to be smaller than the diameter dl of the shank 4, that is, the same diameter as the cutting edge portion 2 (Fig. 21), or a smaller diameter than the cutting edge portion 2 (Fig. 23). More specifically, the distance S from the shank axis O of the cutting edge portion 2 to the cutting edge 5 of the tip l in a front view from the shank axis direction is set to 1.4 seconds or less.

Furthermore, a chip pocket 7 is formed in the cutting edge portion 2 for smoothly discharging chips generated by the cutting blade 5, and the tip side of this chip pocket 7 is connected to the chip I.
It is assumed that the rake face 6 and the approximately face -.

In order to process the inner diameter of a workpiece using the boring tool configured as described above, that is, to expand the diameter of a hole previously formed in the workpiece, first, the shank 4 is moved through a holder (not shown). Tool grips of machine tools (e.g. tailstock of lathes)
At the same time, the workpiece is mounted on a work gripping part of a machine tool (for example, a chuck of a lathe) so that the axis of the hole faces parallel to the axis O of the shank 4.

Then, while rotating the workpiece material around the axis of the hole, a relative movement in the axial direction of the shank 4 is applied between the tool gripping part and the workpiece gripping part of the machine tool, so that the cutting edge part 2 and By inserting part 0 3 into the hole of the workpiece (4), the cutting edge 5 of the tip I cuts the hole of the workpiece to enlarge the diameter to a predetermined size.

[Problems to be Solved by the Invention] By the way, in internal diameter machining using the conventional boring tool described above, the cutting edge portion 2 and neck portion 3 of the boring tool are supported in a so-called cantilever manner protruding from the tool gripping portion of the machine tool. During cutting, chatter vibration is extremely likely to occur in the area from the cutting edge 2 to the neck 3, which can lead to accidents such as deterioration of the surface roughness of the cutting surface and breakage of the cutting edge. The disadvantage was that it was easy to invite

In an attempt to overcome these drawbacks, the neck 3 and shank 4 have conventionally been integrated with cemented carbide and brazed to the cutting edge 2, or the diameter dt of the shank 4 has been made smaller than the diameter dl of the neck 3. Attempts have been made to suppress chatter vibration by increasing tool rigidity and mounting rigidity of the shank 4, such as by making the shank as large as possible. However, with these means, there is a problem that once the stiffness exceeds a certain limit, chatter vibration is no longer reduced as expected even if the stiffness is improved, and there is a certain limit to its effectiveness. Another drawback was that the heavy use of cemented carbide significantly increased raw material costs.

The present invention was made against this background, and an object of the present invention is to provide a boring tool having a novel structure different from conventional ones and having excellent vibration-proofing performance.

[Means for Solving the Problems] In order to solve the above problems, the boring tool of the present invention has a cross-sectional area of the neck in a cross-sectional view perpendicular to the shank axis, which is smaller than the cross-sectional area of the shank in the above-mentioned cross-sectional view. This is the one that was made larger.

In this case, the cross-sectional shape of the neck in the above-mentioned cross-sectional view may be determined as appropriate, but the diameter is l with respect to the distance S from the shank axis to the tip of the cutting blade when viewed from the front in the direction of the shank axis of the cutting edge. It is preferable to form it in a circular shape within the range I of 6S to 1.9S. Also, regarding the length of part 0,
Shank 4III The distance Q from the tip of the cutting blade to the base of the neck in the line direction is 6S to IOs with respect to the above distance S.
It is preferable to set it within the range of .

[Function] According to the above configuration, since the cross-sectional area of the neck is set larger than the cross-sectional area of the shank, it becomes the support side when the boring tool is mounted on a machine tool in a cantilevered state. The rigidity of the shank side is lower than that of the neck side, and the overall structure becomes a flexible structure that is prone to vibration depending on the mass and rigidity (in other words, the spring constant) of each part.

Here, according to the above configuration, the cross-sectional area of the neck portion is larger than that of the shank side, and the mass per unit length of the neck portion is larger than that of the shank side, so that vibration is discontinuous at these joints. Therefore, vibrations generated at the cutting edge due to fluctuations in cutting resistance are not uniformly transmitted to the shank, and as a result, vibrations with different phases and frequencies occur at the joint between the neck and shank. The growth of chatter vibration is inhibited by the interference of the vibrations.

[Example] The present invention will be described in detail below with reference to FIGS. 1 to 3.

As shown in Fig. 2, the boring tool of this actual flow ρj has a cylindrical neck portion 12 and a substantially cylindrical neck portion on the proximal end side of a cutting edge portion 11 with a tip lO attached to one side of the tip. The eggplant shank 13 is formed in sequence.

As shown in FIGS. 1 to 3, the chip 10 includes:
It is made by molding cemented carbide into a plate shape that is approximately rhombic in plan view, and one of the cutting edges 14 formed at the two opposing corners is the above-mentioned cutting edge! It is detachably attached to the cutting edge ill in a state in which it protrudes from the tip and outer periphery of the blade 1 and has a positive rake angle on its rake face 10a.

The height of the cutting edge 14 is set to be substantially the same as the axis O of the shank 13 when viewed from the side of the tip IO (FIG. 3).

The cutting edge portion 11 has a deep pocket I5 that opens toward the tip and upward of the boring tool in a part of the cylindrical body.
It is formed by the formation of

This chip pocket 15 is for smoothly discharging chips growing along the rake surface 10a of the chip 10, and its wall surface is formed at a tip end set at approximately the same height as the axis O of the shank 13. From the part to the cutting edge part! (2) It is formed in the shape of an inclined surface that gradually slopes upward toward the base end. Further, a recess 16 is formed at a position of the chip pocket 15 facing the rear end of the chip IO, which opens on the side facing the chip 10 on the outer circumferential surface of the distal end of the neck portion 12, and the bottom surface 16a of the recess 16 is as follows: Above chip rake face 1
It is set to 0a and road surface -.

Further, the neck portion 12 is a cylindrical body having the same diameter and the same axis as the cutting edge portion 11, and its diameter dt is set larger than the diameter dl of the shank 13, which will be described later.

The diameter dl of this neck portion 12 may be determined as appropriate depending on the cutting conditions, etc., but preferably the diameter dl of the above-mentioned cutting edge portion! [1] when viewed from the front in the direction of the shank 1IilII: 1 for the distance s from the shank axis O to the tip of the cutting blade 14.
It is preferable to set it in the range of 6s to 1.98. Neck 1
The diameter dl of 2 is 1. If the diameter dl exceeds 1.9s, the effect of avoiding chatter vibration due to mass change, which will be described later, may not be sufficiently exhibited.On the other hand, if the diameter dl exceeds 1.9s, the neck
2. The neck when inserted into the hole of the workpiece! This is because there is a possibility that there is insufficient clearance between the outer peripheral surface of the chip pocket 15 and the inner wall of the hole, which may deteriorate the evacuation of chips discharged from the chip pocket 15 via the peripheral surface of the neck portion 12.

Further, the length of the neck portion 12 may be determined as appropriate depending on the length in the axial direction of the hole of the workpiece to be cut.
It is preferable that the distance Q in the shank axis direction from the distal end of the neck part 4 to the proximal end of the neck part 12 be set in the range of 6S to 10S. If the distance Q is less than 68, there is a risk that the vibration-proofing effect due to the flexible structure (7) will not be sufficiently exerted. This is because there is a risk that the machining quality will deteriorate if the temperature becomes too high.

The shank 13 has a notch 17 on the outer peripheral surface of a cylindrical body whose diameter dl is smaller than the diameter dl of the neck 12, which extends over almost the entire length of the shank 13 in the axial direction.
It is designed to be fitted into a holder (not shown) and attached to a tool gripping part of a machine tool.

In order to perform internal diameter machining of a workpiece using the boring tool configured as described above, the shank 13 is attached to the tool gripping part of the machine tool via the holder, as in the conventional boring tool described above. After that, while rotating the workpiece gripped by the workpiece gripping part of the machine tool around the axis of the hole, the shank 13 is inserted between the tool gripping part of the machine tool and the workpiece gripping part. A relative movement in the axial direction is applied to move the cutting edge 11 and neck 12 into the hole H of the workpiece (see Figure 2).
As the cutting edge 14 of the tip 10 is inserted into the hole H of the workpiece, the hole H is expanded to a predetermined size.

At this time, vibration occurs between the cutting edge I4 of the tip IO and the workpiece due to fluctuations in cutting resistance. in this case,
In the conventional boring tool mentioned above, which has high overall rigidity, the entire body vibrates as one rigid body, so vibrations caused by fluctuations in cutting resistance are transmitted from the cutting edge 11 to the neck 12.
is uniformly transmitted to the shank 13 via do.

) Chatter vibration occurs.

However, in the boring tool of this embodiment, the neck 1
Since the cross-sectional area of the shank 13 in the direction perpendicular to the shank axis O of the shank 13 is set larger than that of the shank 13, the shank 13
The rigidity of the side is lower than that of the neck 12 side, and the entire structure becomes a flexible structure that tends to generate vibrations with different frequencies and phases depending on the mass or rigidity (in other words, spring constant) of each part.

Here, in the boring tool of this embodiment, the neck portion 12
Since the mass per unit length of the shank 13 is larger than that of the shank 13, the vibration becomes discontinuous across these joints. Therefore, vibrations generated in the cutting edge II due to fluctuations in cutting resistance are not uniformly transmitted to the shank 13, and as a result, vibrations with different phases and frequencies are generated at the joint between the neck and the shank. , the growth of chatter vibration is inhibited by the interference of these vibrations.

Further, according to the boring tool of this embodiment, since the diameter dl of the neck 12 is larger than the shank diameter d, by abutting the neck end surface 12a against the holder end surface, the axial direction of the boring tool can be adjusted during cutting. By receiving the feed force IL applied toward the shank side, movement of the cutting blade 14 in the shank axis direction can be reliably restrained.

In addition, in this embodiment, the dip 10 is attached detachably, but the present invention is not limited to this.
Naturally, it is applicable even if it is made by brazing or if everything from the cutting edge to the shank is integrally molded.

Further, in this embodiment, the cross-sectional shape of the neck portion 12 is particularly circular, but the present invention is not limited to this, and can be appropriately modified such as a polygonal shape.

Furthermore, in the second embodiment, the shape of the chip pocket 15 is not particularly different from that of the conventional boring tool, but in this embodiment, the neck 15 is
If the diameter dl of the neck 12 is large, the ability to discharge chips from the outer circumferential surface of the neck 12 may be slightly inferior, so as a countermeasure, a groove for discharging chips or the like may be provided in the neck 12. Hereinafter, some modifications of the neck portion I2 will be explained with reference to FIGS. 4 to 19.

(First Modification) The modification shown in FIGS. 4 to 7 has an opening in the outer circumferential surface of the neck 12 in the hollow part 16 of the depth pocket I5, and a neck! From the tip of 2 toward the proximal side,
A torsion groove 20 is formed that gradually twists clockwise when viewed from the tool tip side.

This twist) fermentation 20 is the neck! In a cross-sectional view in a direction perpendicular to the shank axis O of No. 2 (see FIG. 7), the first portion extends in a substantially straight line from near the center of the neck portion 12 toward the outer circumferential surface.
a wall 21 and a bay 111 spaced apart from the first wall 21 starting from the inner end of the first wall 21;
and a second wall portion 22 extending toward the outer circumferential surface while forming a groove, and the first wall portion 21 is continuous with the bottom surface of the recessed portion 16 and is formed between the chip recess surface 10a and the recessed portion 16. ing.

Here, the width of the cross section of the torsion groove 20 may be determined as appropriate depending on the T4 quality of the work material, etc., but by forming the torsion groove 20, the cross-sectional area of the neck 12 will not be less than the cross-sectional area of the shank 13. Please be careful.

Further, the twist angle and twist direction of the twist groove may be determined as appropriate depending on the rake angle of the chip IO.

In the above modification, the chips generated by the cutting blade 14 and discharged to the hollow part 16 of the chip pocket 15 are not discharged to the outer peripheral surface side of the neck part 12, but are passed through the torsion groove 20 to the neck part 12. Since the chips are discharged toward the base end side, the chip discharge performance is significantly improved compared to the case where the chips pass between the circumferential surface of the neck portion 12 and the inner wall of the hole of the workpiece. For this reason, it is possible to avoid accidents such as deterioration of the surface roughness of the cut surface due to clogging of chips, etc., especially in the case of a boring tool with a thick diameter d of the neck portion t2.

(Second Modification) Modifications shown in FIGS. 8 to 11 (the neck portion 12
On the side of the outer periphery connected to the chip 10, the neck part 12 extends over almost the entire length in the axial direction, and has the chip pocket 15.
Nosumi hit! A notch 30 opening at 6 is formed.

Here, the notch amount of the notch 30, that is, the neck 12
In the cross-sectional view (Fig. 11) perpendicular to the thin line of
The recess mm in the radial direction of the notch 30 with respect to the arc n drawn along the outer periphery of the cutout 30 may be determined as appropriate depending on the material of the workpiece, etc.; The cross-sectional area of shank 12 must not be smaller than the cross-sectional area of shank 13 [need to be determined by one circle.

According to this modification, the above-mentioned hollow part! 6 is discharged to the proximal end of the neck 120 through the gap between the notch 16 and the inner wall of the hole of the workpiece, so the chip discharge performance is improved as in the first modification example described above. This has the advantage that the neck portion 12 is improved in one direction, and the neck portion 12 can be formed in one step by simply cutting out the neck portion 12 in one direction, so that it can be formed more easily than the first modification described above.

(Third Modification) In the modification shown in FIGS. 12 to 15, the neck 12
A groove portion 40 is formed on the outer periphery of the neck portion 12, the tip of which opens into the recessed portion 16 and extends linearly from the tip of the neck portion 12 toward the proximal end.

This groove portion 40 extends from the distal end of the neck portion 12 to the proximal end side in a plan view from a direction perpendicular to the flat first wall portion 41 that forms the space between the hollow portion 16 and the first wall portion 41. and a second wall portion 42 that is inclined in a direction that gradually separates from the yank sleeve line O as the direction increases, and each wall portion 41.4
The shape and dimensions of 2 need to be determined within a range such that the cross-sectional area of the neck portion 12 is not less than the cross-sectional area of the shank 13, as in the first and second modified examples.

According to this modification, chips are discharged through the groove 40, so that the cross-sectional area of the neck 12 is reduced by forming the pond and groove 40, which has the same effect as the first modification. The groove portion 40 becomes smaller as it goes from the distal end to the proximal end of the neck portion 12, and as a result, the mass of the entire neck portion 12 is reduced compared to the first and second modifications described above.
This has the effect of minimizing the loss of chatter vibration avoidance effect of the neck portion 12 by forming the neck portion 12.

In this case, if the neck portion 12 has sufficient mass, the second wall portion 42 may be formed as a flat surface extending in the direction parallel to the thin shank wire O, as shown in FIGS. 16 to 19. A groove portion 40 having a constant groove width may be formed.

[Experiment example] Next, an experimental example will be given to clarify the effects of the present invention.

■Experimental example: Prepare the boring tool of the above example, and attach it to a lathe via a holder h as shown in Fig. 20. Processed.

At this time, the protrusion 71 from the end surface of the holder h to the cutting edge 14
1. The ratio of (j,) in Toyank i\DC Figure 1 is 1. /D was varied in three ways, and for each case, the body pressure level of the chattering bowl, the surface roughness of the finished product, and the roundness were measured, and the finished product was visually evaluated.

The results are shown in Table 1.

■Comparative example: Figure 24 (not shown) A conventional boring tool shown in Figure 26 was set to m0, mounted on a lathe, and subjected to internal machining. The ratio L/D between the diameter and the shank diameter was changed in three ways, and the sound pressure level of the chatter sound, the surface Ifi degree and roundness of the finished surface were measured, and the finished surface was visually evaluated 1i15.

The results are shown in Table 1.

In f, i, the measurement frequency of the chatter pressure level in the above Examples and Comparative Examples was set to 4Hz [z].

This means that when boring under normal cutting conditions, 4
This is because chatter noise in the vicinity of kHz is often generated.

Further, the values of L/D in the experimental examples and comparative examples were set as shown in Table 1. Further, the dimensions of each part of the boring tool, the material and dimensions of the workpiece, cutting conditions, etc. in the experimental examples and comparative examples are as shown below.

- Distance from the shank axis to the cutting edge H8...Experimental example 8II1m...Comparative example 8mm -Neck diameter d,...Experimental example 14.
5mm...Comparative example 11.5+nm ・Shank diameter d,...Experimental example 12mm
...Comparative example 12I ・Hole diameter Dw of workpiece material...18+nm ・Hole depth d of workpiece material...20+++m ・Material of workpiece material...
...S0M440 (hardness) (RC28), feed speed...70m/min.

・Feed amount -・-・0, 1 ram/rev.

・Cut jla...0.5+nm or less Margin As is clear from Table 1, the boring tool of the present invention is more effective in reducing chatter vibration than the conventional boring tool. As a result, it was confirmed that the chatter noise during cutting was reduced, and the surface roughness and roundness of the finished surface were improved.

[Effects of the Invention] As explained above, according to the present invention, since the cross-sectional area of the neck is set larger than the cross-sectional area of the shank, the rigidity of the shank side is lower than that of the neck, and the overall structure becomes a flexible structure. Moreover, since the mass per unit length of the neck is larger than that of the shank, the vibration becomes discontinuous across these joints. Therefore, vibrations generated at the cutting edge due to fluctuations in cutting resistance are not uniformly transmitted to the shank, and as a result, vibrations with different phases and frequencies occur at the joint between the neck and shank. This has the excellent effect of inhibiting the growth of chatter vibration due to the interference of the vibrations.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
1 is a plan view, FIG. 2 is a view in the direction of the ■ arrow in FIG. 1, FIG. 3 is a view in the direction of the ■ arrow in FIG. 4 is a plan view thereof, FIG. 5 is a side view thereof, and FIG. 6 is a section III-- in FIG.
7 is a sectional view taken along line IV-IV in FIG. 4, FIGS. 8 to 11 are views showing a second modification of the above embodiment, and FIG. 8 is a plan view thereof. , FIG. 9 is a side view thereof, FIG. 1O is a sectional view taken at 1111 in FIG. 8, FIG. 11 is a sectional view taken along line 1111-Vl in FIG. 12 is a plan view thereof, FIG. 13 is a side view thereof, FIG. 14 is a sectional view taken along line ■-■ in FIG. 12, and FIG.
5 is a sectional view taken along the line ■-■ in FIG. 12, FIGS. 16 to 19 are views showing further modifications of the third modification, FIG. 16 is a plan view thereof, and FIG. 17 is a diagram thereof. 18 is a sectional view taken along line IXIX in FIG. 16, FIG. 19 is a sectional view taken along line X-X in FIG. 16, and FIG. 20 is a diagram showing the cutting form in an experimental example. Figure 23 shows a conventional example; Figure 21 (an outside plan view; Figure 22 a front view thereof; Figure 23 a side view thereof; Figures 24 to 26 show other conventional examples). So, the second
4 is a plan view thereof, FIG. 25 is a front view thereof, and FIG. 26 is a side view thereof. 10...Throwaway tip, 2...Blade tip, 12...Neck, 13...Yank,
14 cutting blades.

Claims (3)

[Claims] (1) A boring bit in which a neck is formed on the proximal side of the cutting edge having a cutting edge on one side of the tip, and a shaft-shaped shank is formed on the proximal side of the neck, the above-mentioned A boring tool characterized in that a cross-sectional area of the neck in a cross-sectional view in a direction orthogonal to the shank axis is larger than a cross-sectional area of the shank in the cross-sectional view. (2) A cross section of the neck in a direction perpendicular to the shank axis is formed circularly, and the diameter of the outer circumferential arc of the neck cross section is from the shank axis in the front view of the cutting edge in the shank axis direction to the tip of the cutting blade. 2. The boring tool according to claim 1, wherein the distance S is set in a range of 1.6S to 1.9S. (3) A distance l from the tip of the cutting blade to the base end of the neck in the axial direction of the shank is set in a range of 6S to 10S with respect to the distance S. A boring tool according to claim 2.