KR950013214B1 - Boring bar tool - Google Patents

Abstract

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Description

Boring bite

1 to 5 show an embodiment of the present invention,

1 degree turning top view,

2 is a view seen from the direction I in FIG. 1,

3 is a view seen from the direction II in FIG. 1,

4 (a) and 4 (b) show the order of formation of the clearance surface;

FIG. 5 is a III-III line cross section, during the first

6 (a) and 6 (b) show a modification of the order of formation of the clearance surface;

7 to 9 are diagrams showing a modification of the above-described embodiment,

7th turning top view,

8th side view,

9 is a cross-sectional view taken along line IV-IV of FIG.

10 is a diagram showing a cutting form in an experiment example;

11 to 13 are diagrams showing a conventional example,

11 is a plan view of a conventional example,

12 is a front view of a conventional example,

13 is a side view of a conventional example,

14 to 16 are diagrams showing another conventional example.

14 is a plan view of a conventional example,

15 is a front view of a conventional example,

16 is a side view of a conventional example.

* Explanation of symbols for main parts of the drawings

(10): Drawaway tip (11): Blade part

(12): neck (13): shank

14: cutting edge 17: clearance

The present invention relates to a boring bite used when performing an inner diameter machining of a workpiece in turning.

Conventionally, as a boring bite, for example, as shown in FIGS. 11 to 13 or 14 to 16, a drawaway tip (hereinafter abbreviated as a tip) 1 is attached to one part of the front end. As a blade portion 2, a cylindrical neck portion 3 formed at the rear end of the blade portion 2, and a substantially cylindrical shank 4 formed at the rear end of the neck portion 3; It is known that it is comprised substantially.

Here, the tip 1 is substantially rhombic in plan view, with any one of the cutting edges 5 formed at opposite head portions protruding from the front end and the outer periphery of the blade portion 2 described above. It is attached to the said blade part 2 so that attachment and detachment are easy.

The diameter d ₁ of the neck portion 3 is smaller than the diameter d ₂ of the shank 4, that is, the same diameter (FIG. 11) or the blade as the blade portion 2 described above. It is set to a diameter smaller than the portion 2 (Fig. 14), and more specifically, the cutting edge of the tip 1 at the shank axis O when viewed from the front in the shank axis direction of the blade portion 2 described above. It is set to 1.4 S or less with respect to the distance S to (5).

Again, the blade portion (2) is formed with a chip pocket (7) for discharging the chips generated by the cutting edge (5) without clogging, the front end of the chip pocket 7 is the tip ( It is substantially one surface with the inclined surface 6 of 1).

In order to use the boring bite configured as described above to widen the inner diameter of the workpiece, that is, to widen the preformed hole in the workpiece, first, the tool fixture of the machine tool (for example, the tailstock of the lathe) through the holder (not shown) of the shank 4 is used. On the other hand, the workpiece is mounted on the workpiece fixture of the machine tool (e.g., on the lathe chuck) such that the axis of the hole portion is directed in the direction parallel to the axis O of the shank 4 described above.

Then, while rotating the above-mentioned work piece around the axis of the hole portion, the relative movement in the axial direction of the shank 4 is applied between the tool fixing tool and the work fixture of the machine tool, so that the blade portion 2 is provided. And by inserting the neck portion 3 into the hole of the workpiece, the hole of the workpiece is cut by the cutting edge 5 of the tip 1 and widened to a predetermined dimension.

By the way, in the inner diameter processing using the conventional boring bite mentioned above, since the cutting part 2 and the neck part 3 of a boring bite protrude from the tool fixture of a machine tool, cutting is performed in the state of the so-called cantilever support. During the cutting, irregular and minute vibrations are likely to occur in the portion from the blade portion 2 to the neck portion 3 during cutting, and therefore, it is easy to cause an accident such as deterioration of surface roughness of the cutting surface or lack of cutting edge. There was a flaw.

In order to solve such a defect, conventionally, the neck portion 3 and the shank 4 are integrated with a cemented carbide and brazed with the blade portion 2 or the shank is smaller than the diameter d ₁ of the neck portion 3. Attempts have been made to suppress irregular vibrations by improving the tool stiffness and the attachment stiffness of the shank 4, such that the diameter d ₂ of (4) is as large as possible.

However, as a means of these means, when the stiffness is exceeded, even if the stiffness is improved, the chatter vibration is not reduced as much as expected, and there is a problem that a certain limit exists in the effect.

In addition, there is a drawback that the raw material cost is significantly increased by using a lot of cemented carbide.

The present invention has been made under such a background, and an object thereof is to provide a boring bite excellent in dustproof performance having a novel structure different from the conventional one.

In order to solve the above-mentioned problems, the boring bite of the present invention has a cross-sectional area at the cutting surface of the shank gradually as the cross-sectional area in the cutting plane in the direction orthogonal to the shank axis advances from the front end to the rear end of the neck portion. It is reduced to a small range and is formed in the shape of an axial shape which has a marginal surface gradually closer toward the shank axis as it goes from the front end to the rear end of the neck portion at the outer peripheral portion of the cutting edge side.

According to the above configuration, since the cross-sectional area in the direction orthogonal to the shank axis of the neck portion decreases as it goes from the front end to the rear end of the neck portion, the rigidity of the shank side is lower than that of the neck portion, and the overall structure According to the mass or the rigidity (in other words, the spring constant), a flexible structure is likely to generate different vibrations.

Here, according to the above configuration, the mass of each part of the neck decreases with the shank as the cross-sectional area of the neck changes, so that the vibration generated in the blade part with variation in cutting resistance is not transmitted uniformly. In the part that extends from the blade end to the back end of the neck, vibrations of different frequencies are generated depending on the mass of each part.

In addition, as the head surface of the cutting edge of the neck moves toward the shank axis from the front end to the rear end of the neck, a clearance surface is gradually approached, so the neck axis position moves from the front end to the rear end. It is gradually spaced apart, and therefore, the transmission direction of vibration also changes sequentially, not coincident in the shank axis direction.

For this reason, even if vibrations are generated in the blade portion with variation in cutting resistance, vibrations of different frequencies or phases occur in each portion of the neck portion and interfere with each other. As a result, growth of chatter vibration is prevented.

In addition, by providing a clearance surface, the gap between the portion continuous to the cutting edge of the neck outer peripheral surface and the inner wall of the hole of the workpiece as the neck is deeply inserted into the hole of the workpiece, that is, as the processing proceeds, This is gradually edging.

For this reason, the chips discharged to the outer circumferential side of the neck even on the cutting edge are easily discharged from the holes through the above-mentioned gaps. As a result, the chip dischargeability is improved, particularly in the case of a deep processing depth, and the chips are cut off. Accidents such as surface damage and cutting edge breakage can be reduced.

EXAMPLE

Hereinafter, embodiments of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the boring bite of the present embodiment has a shank 13 having a neck portion 12 and a substantially cylindrical shape at the end of the blade portion 11 having the tip 10 mounted at one side of the front end. Is formed sequentially.

As shown in FIGS. 1 to 3, the tip 10 is formed of a plate-like shape of a cemented carbide in a substantially rhombic shape, in which one of the cutting edges 14 formed on two opposite angled portions is formed. It protrudes from the front end and the outer periphery of the said blade part 11, and is attached to the blade part 11 easily so that attachment and separation may be carried out in the state in which the inclined surface 10a gave the positive inclination angle. The height of the cutting edge 14 described above is set at approximately the same height as the axis O of the shank 13 described above on the side surface (Fig. 3) of the boring bite.

The said blade part 11 is formed in the circumferential body with the chip | tip pocket 15 which opens to the front end and upper part of the boring bite at the one part in a circumference.

This chip pocket 15 is for discharging the chips growing along the inclined surface 10a of the tip 10 without clogging, and the wall surface thereof is approximately the same height as the axis O of the shank 13 described above. It is formed in an inclined surface shape gradually inclined upward as it goes toward the rear end of the blade portion 11 from the front end set to.

Further, at the position facing the tip end of the tip 10 of the chip pocket 15, a flaw 16 is formed which is open to the side continuous to the tip 10 of the outer peripheral surface of the front end of the neck portion 12. The bottom face 16a of the flaw 16 is formed in substantially one surface with the above inclined surface 10a.

The neck portion 12 is formed of the shank as viewed from the cross section of the shank 13 as the cross-sectional area of the cross section in the direction orthogonal to the shank axis O advances from the front end to the rear end of the neck portion 12. An approximately cylindrical body that reduces the cross-sectional area to a smaller range, and gradually approaches the shank axis O as it goes from the front end to the rear end of the neck portion 12 on the outer side of the side continuous to the tip 10. The clearance 17 is retained.

The diameter d ₁ of the outer circumferential arc in the aforementioned cross section of the front end of the neck portion 12 is appropriately set according to the cutting conditions and the like. The range of 1.6S-1.9S is preferable with respect to the distance S from (O) to the cutting edge 14.

If the diameter (d ₁ ) is less than 1.6S, there is a fear that the avoidance effect of chatter vibration due to the change in orientation described below may not be sufficiently exhibited. On the other hand, if the diameter (d ₁ ) exceeds 1.9S, the neck 12 may The gap between the front end outer circumferential surface of the neck 12 when inserted into the hole of the workpiece and the inner wall of the hole is insufficient, so that the chip pocket 15 passes through the circumferential surface of the neck 12. This is because the dischargeability of the chip to be discharged may deteriorate.

The clearance 17 is formed by turning the neck portion 12 in a direction intersecting the shank axis O at an angle, and the specific formation procedure thereof is as follows.

That is, in the formation of the clearance surface 17, first, as shown in FIG. 4 (a), the neck portion 12a having a larger diameter than the shank 13 at the front end of the shank 13 and having the same axis is formed. ).

Then, as shown in Fig. 4 (b), the rotational axis O ₁ and the shank axis of the neck portion 12a are rotated around the rotation axis O ₁ parallel to the shank axis O. By inserting (O), the bite B is brought into contact with the outer peripheral surface on the opposite side, and the bite B is sent out in a direction intersecting the rotational axis O ₁ at an arbitrary angle θ.

As a result, the outer peripheral portion of the neck portion 12 is gradually cut toward the shank axis O with the transfer of the bite B, as indicated by the inclined line portion in FIG. 4 (b). ) Is formed, and at the same time a neck portion 12 is formed in which the cross-sectional area is gradually reduced.

Here, the inclination angle θ formed by the edge 17A of the clearance surface 17 with respect to the shank axis O may be appropriately set according to the total length, diameter, etc. of the neck 12, but not less than 1 It is desirable to secure more than °. This is because when the inclination angle θ is less than 1 °, the change in the axial center position described later is not sufficient, and the effect of avoiding chatter vibration may be lost.

In the setting of the inclination angle θ, in the cross section at the end of the neck portion 12, that is, in the cross section perpendicular to the shank axis O of the neck portion 12 as shown in FIG. In the area of the part enclosed by the outer circumferential arc R drawn along the outer circumferential surface of the part 12, it is necessary to regulate the removed area of the part removed by the above-described turning not to be smaller than the cross-sectional area of the shank 13. have.

In addition, the length of the neck portion 12 is set appropriately in accordance with the lack of the axial direction of the hole of the workpiece to be cut, but from the front end of the cutting edge 14 to the rear end of the neck portion 12. It is preferable to set so that the distance L in the shank axis direction may be in the range of 6S to 10S with respect to the above-mentioned distance S.

If the distance l is less than 6S, there is a fear that the dust-proofing effect due to the flexible structure as a whole may not be sufficiently extracted. On the other hand, if the distance l exceeds 10S, the cutting resistance of the neck 12 may be reduced. This is because the static torsion caused by the excessive force may cause the degree of processing to deteriorate.

And the said shank 13 forms the notch part 18 extended in the circumferential surface of the cylinder body over substantially the full length of the shank 13 in the axial direction, and it fits in the holder which is not shown in figure, It is intended to be mounted on the machine fixture of the machine.

In order to process the inside diameter of the workpiece using the boring bite configured as described above, the shank 13 is attached to the tool fixture of the machine tool through the holder, as in the conventional boring bite described above, and then the machine tool Rotating the workpiece bited by the work fixture of the workpiece around the axis of the hole portion, while applying the relative movement in the axial direction of the shank 13 described above between the tool fixture of the machine tool and the workpiece fixture, the blade portion 11 ) And the neck 12 are inserted into the hole of the workpiece to cut the hole of the workpiece as the cutting edge 14 of the tip 10 to widen to a predetermined dimension.

At this time, the blade part 11 vibrates with the variation of the cutting resistance between the cutting edge 14 and the workpiece of the tip 10 described above.

In this case, since the whole vibrates as one rigid body in the case where the overall rigidity is high as in the above-described conventional boring bite, the vibration caused by the variation in cutting resistance causes the neck portion 12 to be cut off from the blade portion 11. It is transmitted uniformly to the shank 13 through it, and the part which protruded from the tool fixture of the above-mentioned machine tool in a boring bite, ie, the part from the said blade part 11 to the neck part 12 (it follows) Chatter vibration occurs in the abbreviation).

However, in the boring bite of the present embodiment, the cross section of the neck portion 12 in the direction orthogonal to the shank axis O of the neck portion 12 is formed by forming the clearance surface 17 on the outer peripheral portion of the neck portion 12. As the front end of the head is reduced from the front end to the rear end, the rigidity on the shank 13 side is lower than the front end of the neck part 12, and the overall structure is dependent on the mass or rigidity (in other words, the spring constant) of each part. Therefore, a flexible structure is likely to cause different vibrations.

Moreover, in the boring bite of the present embodiment, the mass of each part of the neck part 12 gradually decreases toward the shank 13 with the change in the cross-sectional area of the neck part 12, so that it occurs in the blade part 11. The vibrations are not transmitted uniformly, and the vibrations varying in frequency depending on the mass of each part occur in the portion from the blade portion 11 to the end portion of the neck portion 12.

Moreover, in the boring bite of this embodiment, by forming the clearance surface 17, as the shaft center of the neck part 12 advances from the front end to the back end of the neck part 12, it is gradually separated from the shank axis O. As a result, the transmission direction of the vibration also changes gradually without being parallel to the shank axis O.

Therefore, even if vibrations are generated in the blade portion 11 with variation in cutting resistance, vibrations of different frequencies or phases are generated in each portion of the neck portion 12 and interfere with each other. As a result, the growth of chatter vibration is increased. It is to be prevented.

In addition, according to this embodiment, since the clearance surface 17 is formed in the side which continues to the tip 10 among the outer peripheral surfaces of the neck part 12, as the neck part 12 is deeply inserted into the hole of a workpiece, that is, , As the processing proceeds, the gap between the side continuous to the tip 10 of the outer circumferential surface of the neck portion 12 and the inner wall of the hole of the workpiece increases gradually.

For this reason, chips discharged to the outer circumferential side of the neck portion 12 via the groove portion 16 of the chip pocket 15 are easily discharged from the holes through the above gaps, and as a result, in particular, the depth of processing In this case, the chip evacuation property is improved, and accidents such as damage to the machining surface due to chip blockage and loss of the cutting edge 14 are avoided, and the next good quality surface can always be obtained by interacting with the fine vibration avoiding effect described above. .

In addition, in the above embodiment, in particular, the tip 10 is easily mounted and detached, but the present invention is not limited thereto, but it is naturally applicable even if it is formed by brazing or integrally molding all the cutting edges to the shank. Will be.

In addition, since the formation procedure of the clearance surface 17 mentioned above shows an example to the last, it is not limited to this.

For example, as shown in Fig. 6 (a), a tapered shaft-shaped neck portion 12a is formed which extends from the shank 13 toward the front end of the shank 13, and then in Fig. 6 (b). As shown, while rotating the neck portion 12a around the axis of rotation O ₂ parallel to the shank axis O, the rotational axis O ₂ and the shank axis O of the neck portion 12a are fitted to the opposite circumferential surface. The bite B is cut.

As shown by the inclined line portion in FIG. 6 (b) by sending the bite B in parallel with the shank axis O, the outer periphery of the neck portion 12a is chamfered and the shank axis O ) than the free surface 17 is located on the outer periphery side of the rotation axis (O ₂₎ is formed.

Again, the shape of the chip pocket 15 of the blade portion 11 is not limited to that of the above-described embodiment.

Hereinafter, this modification is demonstrated with reference to FIGS. 7-9.

In the modification shown in Figs. 7 to 9, the part extending from the front end of the blade portion 11 to the front end of the neck 12 is viewed from the plane of the boring bite (Fig. 7). In the direction intersecting the shank axis O toward the side continuous to the tip 10 of the outer peripheral surface of the front end of the neck 12 near the intersection position between the front end surface of the blade portion 11 and the shank axis O. The chip pocket 20 is formed.

The chip pocket 20 has a flat bottom surface 21 which is substantially one surface with the inclined surface 10a, and a wall surface 22 extending in the direction crossing the shank axis O when the boring bite is viewed in plan. )

Here, the intersection point P ₁ of the edge line and the bottom surface 21 in the front end surface of the blade portion 11 of the wall surface 22 and the distance in the tool diameter direction of the cutting edge 14 described above ( ₁ is set in the range which does not exceed 1.3 S with respect to said distance S.

This is because when the distance L ₁ exceeds 1.3 S, the thickness of the front end of the blade portion 11 is insufficient, and there is a risk that the rigidity improvement effect described later will be lost.

Moreover, the inclination angle (alpha) which the direction in which the said wall surface 22 extends with respect to the said shank axis | shaft O is set in the range of 15 degrees-45 degrees.

When the inclination angle α is less than 15 °, the length of the chip pocket 20 in the shank axis direction may be excessive and the rigidity of the neck portion 12 may be excessively damaged. When α) exceeds 45 °, the angle at which the growth direction of the chip growing along the tip inclined surface 10a and the extending direction of the wall surface 22 cross is excessive, so that the chip smoothly moves toward the outer circumference of the neck 12. This is because there is a fear that can not be guided.

Moreover, the angle (beta) which the bottom face 21 and the wall surface 22 in the cross section orthogonal to the extending direction of the said wall surface 22 of the chip pocket 20 makes is set in the range of 90 degrees-120 degrees. It is.

If the angle β is less than 90 °, the chip pocket 20 may be insufficient to deteriorate chip discharge. On the other hand, if the angle β exceeds 120 °, the tip of the front end of the blade portion 11 may be deteriorated. It is because there exists a possibility that the rigidity of the blade part 11 may be excessively lost because of lack of thickness.

According to such a chip pocket 20, the chip generated from the tip inclined surface (10a) is guided to the wall portion 22 and gradually discharged toward the clearance surface (17), so that the chip discharge property is further compared with the above-described embodiment. Improved cutting efficiency.

In addition, according to the present modification, since the portion opposite to the tip 10 of the blade portion 11 is not notched but is left in the rib shape, the front end of the blade portion 11 is notched over the entire length of the radial direction. Compared with the chip pocket 15 of the embodiment, the cross-sectional area of the blade portion 11 is increased, so that the rigidity of the blade portion 11 is increased.

For this reason, the deformation | transformation of the blade part 11 with the cutting resistance applied to the cutting edge 14 reduces, As a result, the height change of the cutting edge 14 becomes small, and the effect of improving a machining precision is exhibited.

Experimental Example

Next, the effect of this invention is made clear by giving an experimental example.

① Experimental Example The boring bite of the above-mentioned embodiment was prepared, and as shown in FIG. 10, it mounted on the shelf via the holder h, and performed the internal diameter processing of the hole part H of the workpiece W. As shown in FIG.

At this time, the ratio L / D of the protrusion amount L from the end surface of the holder h to the cutting edge 14 and the shank diameter D (d _{2 in} FIG. 1) is changed in three ways, respectively. In this case, the sound pressure level of the chatter vibration sound, the surface roughness and roundness of the machined surface were measured, and visually evaluated.

The results are shown in Table 1.

② Comparative example. The conventional boring bite shown in FIGS. 14-16 was prepared, it mounted on the shelf, and performed internal diameter processing.

At this time, the ratio L / D to the protrusion amount L shank diameter D was changed to three in the same manner as in the experimental example, and the sound pressure level of the chatter vibration sound, the surface roughness of the finished surface, and the roundness were measured. The evaluation was performed.

The results are shown in Table 1.

In the above-described examples and comparative examples, the measurement frequency of the sound pressure level of the chatter vibration sound was set to 4 kHz.

This is because chatter vibration noise near 4 kHz is often generated when boring is performed under normal cutting conditions.

In addition, the value of said L / D in an experiment example and a comparative example was set as shown in Table 1.

In addition, each partial dimension of the boring bite, the material and dimension of a workpiece, cutting conditions, etc. in an experiment example and a comparative example are as shown below.

TABLE 1

As apparent from Table 1, according to the boring bite of the present invention, the chatter vibration is more effectively suppressed than the conventional boring bite, so that chatter vibration noise during cutting is reduced, and the surface roughness and roundness of the finished surface are improved. Was confirmed.

As described above, according to the present invention, the cross-sectional area of the neck portion is gradually changed in the shank axis direction, and the shaft center position of the neck portion is also gradually displaced with respect to the shank axis line, resulting in a change in cutting resistance due to variation in cutting resistance. The vibration generated in the neck is variously changed while being transmitted through the neck to the shank, and vibrations of different frequencies or phases are generated at each part of the neck, and these vibrations cancel each other, thereby effectively suppressing the generation of chatter vibration.

In addition, according to the boring bite of the present invention, as the processing progresses, the clearance between the free surface of the neck outer periphery and the inner wall of the hole of the workpiece is gradually enlarged, so that the chip ejectability is not deteriorated even when the processing depth is increased. Do not.

For this reason, the damage of the processing surface accompanying a chip | tip blockage, or the defect of a cutting edge are avoided, and it matches with the above-mentioned irregular fine vibration avoidance effect, and exhibits the outstanding effect that a favorable process surface is always obtained.

Claims (1)

A neck portion 12 is formed at the rear end of the blade portion 11 provided with the cutting edge 14 at one end of the front end, and a shank 13 having an axial shape is formed at the rear end of the neck portion 12. In the boring bite, the cross section of the cross section in the direction orthogonal to the shank axis O of the neck portion is gradually moved from the front end to the rear end of the neck portion 12, the shank 13 gradually. The margin is reduced to a range not smaller than the cross-sectional area in the cross section of the cross section, and the margin gradually approaches toward the shank axis as the front portion of the neck portion goes from the front end to the rear end portion of the side continuous to the red cutting edge 14 described above. A boring bite, characterized in that formed in an axial shape holding the face (17).

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