JPH0332507A - Boring tool - Google Patents

Abstract

PURPOSE:To obtain a high rigidity at the forward end of a tool and a good work precision by forming a chip pocket in the form of a groove from a posi tion closer to a blade than to an end part on the opposite side to the a blade at a flank at the forward end reaching to a side part connected with the blade in the outer circumferential surface of a tool main body. CONSTITUTION:A chip pocket 20 is formed in the form of a groove from a position closer to a blade 15 than to an end part positioned on the opposite side diametrically to the blade 15 at a flank 16 at the foward end reaching a side part connected with the blade 15 in the outer circumferential surface of a tool main body 13. As a result, the chip pocket 20 extends from the middle of the forward end flank 16 to the side connected with the blade 15 in the outer circumferential surface of the tool, so the forward end part of the tool main body 13 is not cut along the whole diameter as in conventional chip pockets, but it has a rib-like part at the back of the chip pocket 20, that is at a position on the opposite side diametrically to the blade 15 at the forward end of the tool main body 13. The rigidity of the tool forward end is thus improved, and deformation at the forward end of the tool by cutting resistance is decreased.

Description

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

[Prior Art] Conventionally, as shown in FIGS. 6 to 8, this type of boring rebiting tool has been manufactured using a substantially cylindrical tool in which a cutting edge portion 1, a neck portion 2, and a shank 3 are sequentially formed. A scy-”'j'-way tip (hereinafter referred to as
It is abbreviated as chip. ) 5 is known.

Here, the chip 5 has a substantially rhombic shape in plan view,
Either one of the cutting edges 6 formed at the two opposing corners is removably attached to the cutting edge part 1 in a state that slightly protrudes from the tip and outer peripheral surface of the cutting edge part l.

Further, a chip pocket 7 is formed in the cutting edge portion l, which opens at the tip and outer peripheral surface of the boring tool. This chip pocket 7 has a flat rake face 8 which forms a road surface with the chip rake face 5a, and a flat rake face 8 which gradually extends toward the upper outer circumferential surface of the cutting edge 1 as it goes from the rear end of the rake face 8 toward the proximal end of the cutting edge l. 1 and an inclined surface 9 which is inclined all the way.

In order to process the inner diameter of a material to be machined using the thus configured boring tool, that is, to enlarge the diameter of a hole previously formed in the workpiece, first, the shank 3 is moved through a holder (not shown). While attaching the workpiece to the tool gripping part of the machine tool (for example, the tailstock of a lathe), the workpiece is attached to the workpiece gripping part of the machine tool (for example, the chuck of a lathe) so that the axis of the hole is above the Attach it so that it faces parallel to the axis O of the shank 3.

Then, while rotating the work material around the axis of the hole, a relative movement in the axial direction of the shank 3 is applied between the tool gripping part and the workpiece gripping part of the machine tool, so that the cutting edge part l and By inserting the neck portion 2 into the hole of the workpiece, the cutting edge 6 of the tip 5 cuts the hole of the workpiece to enlarge the diameter to a predetermined size.

At this time, chips generated by the cutting edge 6 of the chip 5 are discharged from the chip rake face 5a to the rake face 8 of the chip pocket 7. Then, it is guided to the outer peripheral side of the neck part 2 along the inclined surface 9, and further to the base end side of the boring tool through the gap between the outer peripheral surface of the neck part 2 and the inner wall of the hole of the workpiece. be discharged.

[Problems to be Solved by the Invention] By the way, in the conventional boring tool described above, the cutting surface 8 of the chip pocket 7 is formed by cutting the tip of the cutting edge portion 1 over the entire length in the radial direction. , the rigidity of the cutting edge portion l is considerably lower than that of the neck portion 2 and the shank 3. As a result, the cutting edge 1 is easily deformed by the cutting resistance, changing the height of the cutting edge 6, which causes the inner diameter of the hole to be machined to change, resulting in poor machining accuracy. .

The present invention was made against this background, and an object of the present invention is to provide a boring rebiter that has a high rigidity at the tip of the tool and can realize good machining accuracy.

[Means for Solving the Problems] In order to solve the above problems, the boring tool of the present invention has the above-mentioned tip relief when the above-mentioned chip pocket is viewed from above in a direction perpendicular to the wall surface continuous to the cutting edge. It is formed in a groove shape from the position of the cutting edge ff1l+ beyond the end located on the radially opposite side to the cutting edge of the surface to the side part of the outer circumferential surface of the tool body that is continuous with the cutting edge.

[Function] According to the above configuration, the chip pocket extends from the middle of the tip flank to the groove on the outer peripheral surface of the tool that is connected to the cutting edge. The entire length is not cut, and a rib-like portion remains behind the chip pocket, that is, a portion located on the opposite side in the radial direction to the cutting edge at the tip of the tool body. Therefore, the rigidity of the tool tip is improved and the amount of deformation of the tool tip due to cutting resistance is reduced.

[Example] The present invention will be described in detail below with reference to FIGS. 1 to 4.

As shown in FIG. 1, the boring tool of this embodiment has a tip 14 attached to the tip and side of a substantially cylindrical tool body 13 consisting of a cutting edge portion IO1, a neck portion it, and a shank 12. It is what it is.

As shown in FIGS. 1 to 3, the chip 14 is
It is made by molding cemented carbide into a plate shape that is approximately rhombic in plan view, and one of the cutting edges 15 formed at two opposing corners is the tip flank 16 of the cutting edge portion IO and the outer circumferential surface. 17
It is removably attached to the tip-to-side portion of the cutting edge portion IO in a state in which it protrudes from the blade and a positive rake angle is given to its rake face 18. The height of the cutting edge 15 is as follows in the side view of the boring tool (FIG. 3):
It is set at approximately the same height as the axis O of the shank 12.

Further, on the outer periphery from the cutting edge IO to the neck IT of the tool body 13, the tip and upper part of the boring rebit (
A chip pocket 20 is formed that opens upward (in FIG. 3).

The chip pocket 20 includes a flat bottom surface 21 that extends linearly in the radial direction of the cutting edge portion IO and forms a substantially plane with the chip rake surface 18, and a flat bottom surface 21 that protrudes from the bottom surface 21 and extends straight in the radial direction of the cutting edge portion IO. The neck l! extends linearly in a direction intersecting the shank axis O from a portion closer to the tip 14 than the end located on the radially opposite side to the tip 14 of the neck l!
It has a vertical wall surface 22 extending to a side of the outer circumferential surface connected to the chip I4.

As shown in FIG. 2, the vertical wall surface 22 is connected to the bottom surface 21.
It is composed of a circular arc portion 23 continuous to the circular arc portion 23, and a flat portion 24 continuous to the circular arc portion 23 and linearly ductile to the outer peripheral surface of the tool.

As shown in FIG. 1, the angle α between the extending direction of the vertical wall surface 22, that is, the intersection line 25 drawn at tO at the point where the circular arc portion 23 intersects the bottom surface 21, and the shank axis O is It can be windowed as appropriate depending on the material etc., but as much as possible! 5°
It is preferable to set it in the range of ~45°. Angle α is 15
If the angle α is less than 45°, the length of the chip pocket 20 in the shank axis direction will become too long, and the stiffness of the neck 11 may become excessively large.
If the angle exceeds the angle between the growth direction of the chips growing on the chip rake face 18 and the extending direction of the vertical wall surface 22, there is a possibility that the chips cannot be smoothly guided to the outer circumferential side of the recessed portion 11. This is because

Further, the distance Ql in the tool radial direction from the point PI where the ridge line on the tip flank i6 of the vertical wall surface 22 intersects with the bottom surface 21 to the cutting edge 15 is the distance Ql in the tool radial direction from the shank axis O to the cutting edge 15. When the distance is S, 1.
It is preferable to set it within a range not exceeding 39. Distance Ql
This is because if it exceeds 3s, the wall thickness in the circumferential direction at the tip of the cutting edge portion 10 will be insufficient, which may reduce the tool rigidity.

In addition, the inclination angle of the vertical wall surface 22 with respect to the bottom surface 21, that is, as shown in FIG. The angle β formed by the flat part 24 of 22 is
The window can be adjusted as appropriate depending on the cutting conditions, etc., but preferably 90
It is preferable that the angle β be in the range of 12° to 12°.
This is because if the angle exceeds 0°, the wall thickness at the tip of the cutting edge portion lO may be insufficient and sufficient rigidity may not be obtained.

As shown in FIGS. 1 to 3, the neck portion 11 is formed on the outer circumferential surface of the implantation body, which is formed to have a larger diameter than the shank 12. Relief portions 26 are formed that gradually approach the shank axis ◯ from a position connected to the opening of the tip pocket 20 at the tip end toward the base end of the neck portion 11.

The protruding portion 26 is formed by cutting out the outer circumferential portion of the neck portion 11 in a substantially crescent shape in a cross-sectional view perpendicular to the soyank axis O. Therefore, the shape of the cutout portion is the same as that of the neck portion 11. The cross-sectional area of each part in the above cross-sectional view is
The neck 11 within a range not less than the cross-sectional area of the shank 12
It is determined that it decreases unevenly from the distal end to the proximal end.

The length of the neck 11 is determined as appropriate depending on the length in the axial direction of the hole of the workpiece to be cut, but the length of the shank from the tip of the cutting blade I5 to the base of the neck 11 is The distance in the axial direction is 68 to IOs for the above distance S.
It is preferable to set it within the range of . The distance is 6
If the distance is less than 8, as will be described later, there is a risk that the vibration damping effect of having a flexible structure as a whole will not be sufficiently exhibited.On the other hand, if the distance exceeds 109, the amount of bending deformation due to cutting resistance of the neck 11 will be reduced. This is because there is a risk that machining accuracy will deteriorate if the size becomes too large.

In order to perform internal diameter machining of a workpiece using the boring rebit machine configured as described above, the shank 12 is passed through the holder to the tool of the machine tool, similar to the conventional boring part 17 mentioned above. After that, while rotating the workpiece +4 held by the workpiece gripping part of the machine tool around the l1ll line of the hole, a By applying relative movement in the axial direction of the shank 12 and inserting the cutting edge 10 and the neck portion 11 into the hole of the workpiece, the cutting edge 15 of the tip 14 moves the workpiece 11.
+ Cut the hole at the mouth and expand the diameter to the specified size.

At this time, since a cutting resistance in a direction substantially perpendicular to the chip scooping weight 8 is applied to the cutting edge portion IO, the cutting edge portion 10 is cut over the entire radial length as in the conventional boring bit described in [5] above. If the rigidity of the chipped edge portion 10 is low, the edge portion IO is easily deformed by cutting resistance, and the height of the cutting edge 15 changes accordingly, resulting in deterioration of machining accuracy.

However, in the center rebiting of this embodiment, the vertical wall surface 22 of the tip pocket 20 is shunted from a portion closer to the tip 14 than the end portion of the distal end face 16 located on the opposite side in the radial direction with respect to the tip t4. Because it extends in the direction intersecting the axis O, the tip portion of the cutting edge portion 10 is not cut out over the entire radial length like the conventional chip pocket 7, but is cut out behind the chip pocket 20, that is, at the tip of the cutting edge portion 10. A portion located radially opposite to the tip 14 is left in the shape of a rib. Therefore, the rigidity of the cutting edge portion 10 is improved, the amount of deformation of the cutting edge portion 10 due to cutting resistance is reduced, and as a result, changes in the height of the cutting edge are reduced, and good machining accuracy can be achieved.

In this case, the chips generated by the cutting edge 15 grow along the bottom surface 21 of the chip pocket 20, are rolled up along the arcuate portion 23 of the vertical wall surface 22, and continue along the flat portion 24 of the neck portion 1.
It is successively guided to the relief part 26 on the outer periphery. Therefore, even if the chip pocket 20 is not cut out over the entire radial length of the cutting edge portion 10, the chip evacuation performance will not deteriorate in any way.

Furthermore, since the protruding portion 26 gradually approaches the shank axis 0 from the distal end to the proximal end of the neck portion 11, the cutting edge portion I
As the O and the placing part 11 are inserted into the hole of the workpiece, that is, as the machining progresses, the gap between the O and the inner wall of the hole of the workpiece increases.

Therefore, even if the machining depth becomes deep, the chip evacuation property is effectively maintained.

In addition, in the center rebiting of this embodiment, as the cross-sectional area of the neck 11 changes, the mass of each part of the neck 11 changes from the shank 1.
It decreases unevenly toward 2, and furthermore, the relief part 2
6, the fine position of the neck 11 gradually deviates from the shank axis 0, so even if vibration occurs at the cutting edge IO due to fluctuations in cutting resistance, this vibration will be uniformly transmitted to the shank 12. never transmitted. Therefore, the neck l! Various vibrations with different frequencies and phases occur in each part of the motor and interfere with each other, and as a result, the growth of chatter vibration is also inhibited.

Note that in the above embodiments, the tip 14 is detachably attached, but the present invention is not limited to this, and the present invention is not limited to this. However, it is naturally applicable.

Further, the vertical wall surface 22 of the chip pocket 20 does not necessarily have to extend linearly in a direction intersecting the shank axis O, but for example, as shown in FIG. Various modifications such as providing 28 are possible. In this case, the distance Q from the point Pl where the ridge line and the bottom surface 21 intersect on the tip end surface 16 of the vertical wall surface 22 to the cutting edge +5 is preferably set in the same range as in the above embodiment; From the tip of the neck l of the vertical wall surface 22! Regarding the distance Ql to the point Pl where the ridgeline on the outer peripheral surface side and the bottom surface 2I intersect, 121~
It is preferable to set it within the range of 3Q1.

If the distance Ql is less than Ql, the direction in which chips are discharged from the chip pocket 20 toward the outer circumferential surface of the neck 11 is too inclined with respect to the shank axis @O, and the chips are smoothly directed toward the proximal end of the neck 11. There is a risk that you will not be guided, and on the other hand, the distance Ql
This is because if exceeds 3Ql, the length of the notch in the axial direction of the neck portion 11 becomes large, and there is a risk that the rigidity will be excessively impaired.

Furthermore, the shape of the neck portion 11 is not limited to the shape of this embodiment, but can naturally be applied to those with a smaller diameter than the shank 3, such as the conventional medium-sized bits shown in FIGS. 6 to 8. can.

[Effects of the Invention] As explained above, according to the present invention, the tip of the tool body is not notched over the entire length in the radial direction, and the part on the opposite side in the radial direction to the cutting edge is shaped like a protrusion. Because it will be left behind,
The rigidity of the tip of the tool body is improved, and the amount of deformation of the tip of the tool due to cutting resistance is reduced. For this reason, it is possible to prevent changes in the height of the cutting edge due to deformation of the tool tip, and achieve excellent machining accuracy.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention,
Figure 1 is a plan view, Figure 2 is a view in the direction of the I arrow in Figure 1, Figure 3 is a view in the direction of the ■ arrow in Figure 1, and Figure 4 is a view in the direction of the ■ - in Figure 1.
5 is a plan view showing a modified example of the above embodiment, FIGS. 6 to 8 are views showing a conventional example, FIG. 6 is a plan view thereof, and FIG. 7 is a front view thereof. FIG. 8 is a side view thereof. 13... Tool body, 14... Throwaway tip, 1.5... Cutting blade, 20...
Chip pocket, 1 Bottom surface (wall surface connected to the cutting edge).

Claims (1)

[Scope of Claims] A chip pocket opening to the tip flank and outer peripheral surface of the tool body is formed at the tip of the tool body having a substantially cylindrical shape, and the tip of the tool body is formed on the tip wall of the chip pocket. and a boring tool provided with a cutting edge protruding from the outer periphery, when the chip pocket is viewed in plan from a direction perpendicular to the wall surface continuous to the cutting edge, with respect to the cutting edge of the tip flank. A boring bit characterized in that a groove is formed from a position closer to the cutting edge than an end located on the opposite side in the radial direction to a side portion of the outer peripheral surface of the tool body that is continuous with the cutting edge.