JP2003291003A - Cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool with a longitudinal shape in section at the head portion 3 causing no bending at the head portion 3 even when performing spherical surface machining and deep end face machining on the hole bottom of a machined hole while restraining trembling. <P>SOLUTION: The head portion 3 with a longitudinal shape in section transverse to a shaft line O of this shaft-shaped tool body 1 is formed on a tip part of the tool body 1, and a cutting edge 7a is formed on tip part of the head portion 3. A chip pocket 4 having a bottom surface 5 extending so as to range to a cutting face 7b of the cutting edge 7a is formed on one end side in the longitudinal direction of section of the head portion 3, and a recess 9 recessed to the other end side in the longitudinal direction of the section is formed on the bottom surface 5 of the chip pocket 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool for making a hole in a workpiece, and particularly suitable for making a spherical surface or a deep end surface on the hole bottom of the hole to be formed. It is about tools.

[0002]

2. Description of the Related Art A cutting tool of this kind for making a hole in a work is disclosed in, for example, Japanese Unexamined Patent Publication No. 11-285906 and Japanese Unexamined Patent Publication No. 2001-105204, in which the outer peripheral surface of the head portion at the tip of a shaft-shaped tool body is Among them, there is proposed one in which a concave groove is formed on the back surface portion on the side opposite to the cutting edge with respect to the axis of the tool body. However, according to such a cutting tool, since the weight of the head portion is reduced and the natural frequency is increased by the amount of the formation of the concave groove, the natural frequency of the mechanical system including the cutting tool and the natural frequency are increased. It is possible to prevent the occurrence of chattering due to resonance by increasing the deviation from the frequency of the external force.

[0003]

By the way, in such hole machining, for example, when the inner diameter of the machined hole formed in the work is small, the head section is avoided while avoiding interference between the head section and the inner periphery of the machined hole. To ensure the largest possible cross-sectional area, the cross section of this head section, which is orthogonal to the axis of the tool body, has a vertically elongated shape with a middle bulge that connects two arcs whose outer shape is approximately the same radius as the inner diameter of the machining hole at both ends. It is formed so that However, in such a cutting tool, when the concave groove is formed on the back surface of the head portion as described above, the wall thickness of the head portion is reduced in the width direction orthogonal to the longitudinal direction of the vertically elongated shape formed by the cross section of the head portion. There is a risk of peeling and impairing the rigidity against the back force acting during processing. In particular, when spherical machining is performed to make the hole bottom of the machined hole into a concave spherical shape or deep end face machining is performed to finish the hole bottom on a plane perpendicular to the center line of the machined hole, the tool body is It is necessary to perform cutting while moving in the width direction of the head part, and if the thickness in the width direction of this head part is cut off in the cutting tool used for such processing, the head is moved when moving the tool body. The portion may be bent, which may lead to deterioration in processing accuracy.

The present invention has been made under such a background, and suppresses the occurrence of chattering vibration in a cutting tool having a vertically elongated cross section of the head portion as described above,
In particular, it is an object of the present invention to provide a cutting tool that does not cause the head portion to bend even when such spherical surface processing or deep end surface processing is performed on the hole bottom.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems and to achieve such an object, the present invention is directed to a tip end portion of a tool body having an axial shape and a cross section orthogonal to the axis of the tool body. Forms a vertically elongated head portion, and a cutting blade is provided at the tip of this head portion, and one end side in the longitudinal direction of the cross section of the head portion is connected to the rake face of the cutting blade. It is characterized in that a chip pocket having an extending bottom surface is formed, and a concave portion that is recessed toward the other end portion in the longitudinal direction in the cross section is formed in the bottom surface of the chip pocket. Therefore, in such a cutting tool, a concave portion is formed on the bottom surface of the chip pocket formed on one end side in the longitudinal direction of the longitudinal shape formed by the cross section of the head portion so as to be recessed on the other end side in the longitudinal direction. Since the weight is reduced by forming the concave portion, the natural frequency can be increased and the occurrence of chatter due to resonance can be suppressed, while the head portion does not have its thickness reduced in the width direction of the cross section. It is possible to sufficiently secure the rigidity against the back force, and even when the tool body is moved in the width direction particularly when performing the above-mentioned spherical surface processing or back end surface processing, the head portion may be bent. Can be prevented.

By forming a recessed portion on the bottom surface of the chip pocket on the one end side in the longitudinal direction in the above-mentioned cross section of the head portion, the thickness of the head portion in the longitudinal direction, that is, the direction in which the main component force acts during machining. The thickness is reduced and the rigidity is impaired. Therefore, in order to suppress the deterioration of the rigidity against the main component force while forming such a concave portion, in order to suppress the deterioration of the rigidity against the main component force, the concave portion is formed between the outer edge of the bottom surface of the chip pocket and the opening edge of the concave portion. It is desirable that the recess be formed so as to be spaced apart from each other so that the recess does not open on the back surface of the head portion or the side surface on the opposite side to the bottom surface of the chip pocket between the recess and the back surface or the side surface. Since the rib-shaped portion in which the portion is left is defined and the dimension in the longitudinal direction of the head portion can be maintained to be equal to that in the case where the concave portion is not formed, the rigidity against the main component force is also sufficient. It becomes possible to secure. Further, according to the present invention, since the volume of the chip pocket can be increased by forming such a recess on the bottom surface of the chip pocket, the spherical surface processing or the deep end surface processing can be performed especially on the bottom of the processing hole. It is also possible to obtain the effect that the chips generated during the process can be smoothly discharged from the processed hole without causing clogging.
Therefore, in order to more reliably bring out such an effect, it is desirable that the bottom surface of the concave portion is formed into a concave curved surface, so that the chips contained in the concave portion can be smoothed. In addition, it is possible to guide it to the rear of the chip pocket and reliably discharge it from the processed hole.

[0007]

1 to 6 show an embodiment of the present invention. In the present embodiment, the tool main body 1 is formed of a steel material or the like and has a shaft-like shape including a shank portion 2 having a substantially cylindrical outer shape and a head portion 3 on the tip side thereof as shown in FIG. 3 is biased to one side of the outer periphery of the shank portion 2 with respect to the axis O of the tool body 1 passing through the center of the shank portion 2 (upper side in FIGS. 2 and 3, left side in FIGS. 5 and 6). It is formed so as to extend toward the tip side in parallel to the axis O. On the outer peripheral surface of the shank portion 2, a pair of flat surfaces 2a, 2a parallel to each other and parallel to the axis O are formed over the entire length of the shank portion 2 in the direction of the axis O. Further, on the outer periphery of the tip end portion of the shank portion 2, a scale 2b for measuring the insertion depth of the head portion 3 into the processed hole is provided on the side opposite to the side where the head portion 3 is formed unevenly. There is. further,
An inclined surface 2c is formed at a connecting portion between the shank portion 2 and the head portion 3 so as to project toward the tip side as the head portion 3 is biased.

The head portion 3 has a back surface 3a facing the side where the head portion 3 is biased as described above and a side surface 3b located on the opposite side of the back surface 3a in a cross section orthogonal to the axis O as shown in FIG. As shown in the drawing, they are formed so as to form arcuate shapes that are convex in opposite directions and extend in the direction of the axis O, so that the cross section of the head portion 3 is perpendicular to the direction in which the head portion 3 deviates from the axis O. A vertical direction (a vertical direction in FIG. 6) is defined as a longitudinal direction, and a central portion in the longitudinal direction bulges in a width direction orthogonal to the longitudinal direction to form a vertically bulged shape. However, the longitudinal direction of the vertically elongated shape, that is, the longitudinal direction, is the direction perpendicular to the direction in which the head portion 3 deviates from the axis O in the cross section as described above, that is, the arc formed by the back surface 3a and the side surface 3b intersects. The chord of the arc connecting the both ends of the arc extends. For example, the longitudinal direction may extend laterally depending on the arrangement of the tool body 1. The radius of the arc formed by the side surface 3b in the cross section is slightly larger than the radius of the arc formed by the back surface 3a, and is substantially the same as or slightly smaller than the inner diameter (radius) of the machining hole machined by the cutting tool. Has been done.

Further, one end in the longitudinal direction of the head section 3 in the cross section, that is, the back surface 3a in the cross section.
One end (upper end in FIG. 6) of the above-mentioned both ends where the arc formed by and the side surface 3b intersects, from the front end of the head part 3 toward the rear end side, The chip pocket 4 is formed by cutting out the ridge line portion where the back surface 3a and the side surface 3b intersect. Here, the bottom surface 5 of the chip pocket 4 formed in the head portion 3 facing the one end side by being cut out in the chip pocket 4 in this way has a portion on the tip end side of the head portion 3 as the axis O.
On the other hand, a gentle gentle slope 5a is formed as a flat gentle slope 5a that slopes toward the one end in the longitudinal direction as it goes toward the rear end, and a steep slope 5b at which the slope once becomes steep is formed on the rear end. Further, the inclination becomes gentle again on the rear end side so as to intersect the intersection ridge portion before the connecting portion between the shank portion 2 and the head portion 3. In addition, in the width direction, the bottom surface 5 extends from the side surface 3b side to the back surface 3a as shown in FIGS.
As it goes toward the side, it is gently inclined toward the one end side in the longitudinal direction (the upper side in FIGS. 5 and 6).

On the other hand, as shown in FIG. 3, the tip surface 3c of the head portion 3 extends obliquely from the back surface 3a side to the side surface 3b side toward the tip side so as to intersect the side surface 3b at an acute angle. As shown in FIG. 4, the intersecting ridge portion of the tip surface 3c and the side surface 3b is formed toward the bottom surface 5 side of the chip pocket 4 while drawing a convex curve in a side view facing the side surface 3b. It has been rounded up. Therefore, since the tip end surface 3c is formed obliquely in this way, the bottom surface 5 and the gentle slope 5a on the tip end side are
The ridge line intersecting with the side surface 3b and the ridge line intersecting with the tip surface 3c are formed in a substantially triangular shape having a corner portion at the tip that intersects at an acute angle. In the present embodiment, the chip mounting seat formed at this corner portion is formed. A throw-away tip (hereinafter referred to as a tip) 7 is detachably attached to the tip 6.
The cutting edge 7a formed in the above is provided at the tip of the head portion 3.

Here, the chip 7 in this embodiment is
A negative tip formed of a hard material such as cemented carbide in the shape of a substantially rhombic flat plate, the face forming the substantially rhombus is a rake face 7b, and the cutting edge is provided around a corner portion forming an acute angle of the rake face 7b. 7a is formed. A mounting hole 7c is formed from the center of the rake face 7b so as to penetrate the chip 7 in its thickness direction. On the other hand, the tip mounting seat 6 to which such a tip 7 is attached is formed as a recess that is recessed from the gentle slope 5a of the bottom surface 5 by approximately the thickness of the tip 7 and opens to the side surface 3b and the tip surface 3c. A bottom surface 6a having substantially the same shape as the diamond shape formed by the rake face 7b and parallel to the gentle slope 5a, and the bottom surface 6a.
Is provided with a wall surface 6b that rises from the peripheral edge of the wall surface and that is continuous with the gentle slope surface 5a and that intersects the side surface 3b and a wall surface 6c that intersects the tip surface 3c, and a screw hole (not shown) is formed in the center of the bottom surface 6a. .

In the tip mounting seat 6 thus configured, the tip 7 of the tip 7 has its rake face 7b directed toward the one end side in the longitudinal direction and the cutting edge 7a is directed to the head portion 3.
The rhombus surface opposite to the rake surface 7b is brought into close contact with the bottom surface 6a, and two side surfaces continuous with the corner portion located diagonally of the corner portion where the cutting edge 7a is formed are connected to the wall surface. Clamp screw 8 which is seated by abutting against 6b and 6c, and which is vertically inserted into the mounting hole 7c.
Is fixed by screwing into the screw hole of the bottom surface 6a. The cutting edge 7a of the tip 7 thus mounted is located at substantially the same height as the axis O of the tool body 1 in the longitudinal direction, and the bottom surface 6 of the tip mounting seat 6 is also located.
By sloping the gentle slope 5a of the bottom surface 5 of the chip pocket 4 in which a is parallel to each other as described above, the cutting edge 7a is provided with a negative front rake angle and a side rake angle, and at the same time, the rake face. 7b is arranged so as to be substantially flush with or slightly recessed from the gentle slope 5a and to be continuous with the bottom surface 5 of the chip pocket 4.

In this embodiment, at the portion of the steep slope 5b behind the gentle slope 5a, on the bottom surface 5 of the chip pocket 4, the other end portion in the longitudinal direction of the vertically elongated shape formed by the head portion 3 in the cross section ( A recess 9 is formed which is recessed toward the lower side in FIG. 6, that is, the side opposite to the side on which the chip pocket 4 is formed. This recess 9 is
The opening edge 9a to the bottom surface 5 (steep slope 5b) is the bottom surface 5
When viewed from the direction opposite to, the outer periphery of the bottom surface 5 of the chip pocket 4 is formed into an oval shape as shown in FIG.
That is, the bottom surface 5 and the ridge portion intersecting with the back surface 3a and the side surface 3b are formed with a space therebetween. Therefore, in the above-mentioned cross section orthogonal to the axis O, FIG.
As shown in FIG. 5, the steep slope 5b of the bottom surface 5 of the chip pocket 4 is slightly left between the recess 9 and the back surface 3a and side surface 3b of the head portion 3. Further, the bottom surface 9b of the concave portion 9 is formed so as to form a smooth concave curved surface as a whole, and particularly in the axis O direction,
The tip end side thereof has an inclination angle substantially equal to that of the gentle slope 5a, and is curved so as to go toward the rear end side and is cut up toward the rear end side edge portion of the steep slope 5b.

In the cutting tool constructed as described above, the shank portion 2 is held by the tool rest of the machine tool, as shown in FIG.
As shown in FIG. 8 or FIG. 8, the machined hole H is formed in the work W by inserting the head portion 3 into the work W rotatably chucked by the machine tool. At this time, the cutting tool has its axis O substantially parallel to the rotation axis C of the work W, the rake face 7b of the tip 7 faces the rotation direction of the work W, and the side face 3b of the head 3 is machined. By being held facing each other along the inner circumference of the hole H and being fed to the tip end side in the direction of the axis O as shown by the arrow A in the figure to cut the cutting edge 7a into the work W, The machining of the machining hole H centering on the rotation axis C of the work W is performed. At the time of this processing, a prepared hole is previously formed in the work W, and the inner periphery of the prepared hole is formed by the cutting blade 7
The machined hole H may be formed by cutting with a, or the machined hole H may be directly formed in the workpiece W having no prepared hole.

In the cutting tool having the above structure, however, since the concave portion 9 is formed in the head portion 3 at the tip of the tool body 1 as described above, the weight of the head portion 3 can be reduced and the cutting tool can be used. The included natural frequency of the mechanical system of the machine tool or the like can be largely deviated from the frequency of the external force acting on the tool body 1 by cutting. For this reason, when the natural frequency and the frequency of the external force match and resonate, chatter vibration occurs particularly in the head portion 3 of the tool main body 1 and the machining accuracy is impaired, and the cutting edge 7a and the tool main body 1 are damaged. It is possible to prevent a situation such as damage.

The recess 9 is recessed in the bottom surface 5 of the chip pocket 4 formed at one end in the longitudinal direction of the cross section of the head portion 3 having a vertically long cross section, toward the other end in the longitudinal direction. Since it is formed, the wall thickness of the head portion 3 is not shaved in the width direction orthogonal to the longitudinal direction, and the rigidity of the head portion 3 is sufficiently secured against the back force acting in this direction. be able to. Therefore, for example, even when the inner diameter of the processed hole H is small and therefore the width of the head portion 3 inserted into the processed hole H must be limited, the head portion 3 is bent by the back force. It is possible to reliably prevent a situation in which the machining accuracy is impaired or the tool body 1 is damaged due to the occurrence of.

Further, after forming the machined hole H having a predetermined depth in the work W in this way, as shown in FIG. 7, a concave spherical surface R having a center on the rotation axis C is formed at the hole bottom of the machined hole H. In the case of performing the spherical surface machining to be performed, or performing the deep end surface machining that forms the end surface E orthogonal to the rotation axis C in the deep part of the machining hole H as shown in FIG. The concave spherical surface R and the end surface E are continuously formed on the inner diameter of the processed hole H.
The tool body 1 is moved toward the inner peripheral side (rotation axis C side) of the machined hole H in the width direction of the head portion 3 while the cutting blade 7a is cut into the work W along the line. Even in such a case, according to the cutting tool, since the rigidity of the head portion 3 in the width direction is sufficiently secured,
It is possible to suppress the bending of the head portion 3 in the width direction. Therefore, according to the cutting tool having the above-described configuration, not only in the case of the normal inner diameter machining of the machining hole H, but also in such spherical surface machining and deep end surface machining, the machining hole H of high precision can be smoothly and stably formed on the work W. In addition, the spherical surface processing and the rear end surface processing can be continuously performed with the inner diameter processing without any trouble, and the processing efficiency can be improved.

Further, in this embodiment, the opening edge 9a of the recess 9 is formed so as to be spaced from the outer peripheral edge of the bottom surface 5 of the chip pocket 4, whereby the recess 9 is formed. The bottom surface 5 is left on both sides of the steep slope 5b in the bottom surface 5 of the chip pocket 4, and a rib-shaped portion having the same height as the bottom surface 5 is defined in the longitudinal direction. Head part 3 to surround the
Will be continued from the front end side to the rear end side. Therefore, according to the present embodiment, the rigidity of the head portion 3 in the longitudinal direction is remarkably high although the concave portion 9 is formed so as to be depressed in the longitudinal direction of the longitudinal cross section of the head portion 3 as described above. The damage can be suppressed by the rib-like portion, and the bending of the head portion 3 is suppressed even with respect to the main component force of the cutting that acts in the longitudinal direction during processing, thereby degrading the processing accuracy and the tool body. It is possible to prevent the damage of item 1.

On the other hand, according to the cutting tool having the above-described structure in which the concave portion 9 is formed on the bottom surface 5 of the chip pocket 4, the concave portion 9 can increase the volume of the chip pocket 4, and therefore, during machining. There is also an advantage that the chips to be cut can be accommodated in the chip pocket 4 including the recess 9 and reliably discharged. In particular,
When the hole bottom of the processed hole H is processed like the above-described spherical surface processing or deep end surface processing, depending on the depth of the processed hole H, for example, most of the chip pockets 4 are processed holes as shown in FIG. Processing may be performed in a state of being housed in H, and even in such a case, according to the cutting tool,
It is possible to reliably discharge the chips from the machining hole H via the recess 9 and prevent a situation in which the chips accumulate in the machining hole H and hinder smooth machining.

Moreover, in the present embodiment, since the bottom surface 9b of the recess 9 is formed into a concave curved surface, chips are not clogged even in the recess 9, and therefore such an excellent feature is obtained. It becomes possible to more reliably achieve the chip discharging property. Further, particularly in the present embodiment, the tip side of the bottom surface 9a of the concave portion 9 has an inclination angle substantially equal to that of the gentle slope 5a on the tip side of the bottom surface 5 of the chip pocket 4 which is continuous with the rake surface 7b of the cutting blade 7a. Chips generated by the blade 7a and rubbing the rake face 7b can be reliably guided from the gentle slope 5a connected to the rake face 7b to the bottom 9b, guided to the recess 9, and discharged to the rear of the head part 3. Therefore, even when the feed direction (movement direction) of the tool body 1 is changed such that the outflow direction of the chips is likely to be changed as in the case of the spherical surface processing or the deep end surface processing, it is possible to promote more reliable chip disposal. It will be possible.

[0021]

As described above, according to the present invention,
By forming a recessed portion on the other end side in the bottom surface of a chip pocket formed at one end in the longitudinal direction of the cross-section of the head having a vertically elongated shape, the weight of the head is reduced and the natural vibration of the mechanical system is achieved. The number from the frequency of the external force,
It is possible to prevent the occurrence of chattering, of course, it is possible to suppress the back force acting during processing, and the deflection due to the load when performing spherical surface processing or deep end surface processing on the hole bottom of the processing hole,
It is possible to prevent a situation in which the processing accuracy is impaired or the tool body is damaged due to such bending.

[Brief description of drawings]

FIG. 1 is a perspective view of a tip portion of a tool body 1 showing an embodiment of the present invention.

FIG. 2 is a plan view of the embodiment shown in FIG.

FIG. 3 is an enlarged plan view of a tip portion of the tool body 1 of the embodiment shown in FIG.

FIG. 4 is an enlarged side view of the tip portion of the tool body 1 of the embodiment shown in FIG.

5 is an enlarged front view of the tip portion of the tool body 1 of the embodiment shown in FIG. 1 as viewed from the tip side in the direction of the axis O. FIG.

6 is a ZZ cross-sectional view in FIG.

FIG. 7 is a plan view showing a case where the hole bottom of the processed hole H is spherically machined according to the embodiment shown in FIG. 1;

8 is a plan view showing a case where a deep end surface of the hole bottom of the processed hole H is processed according to the embodiment shown in FIG. 1. FIG.

[Explanation of symbols]

1 Tool body 3 head 3a Back of head part 3 3b Side of the head unit 3 4 chip pockets 5 Bottom of chip pocket 4 7a cutting edge 7b rake face 9 recess 9a Opening edge of recess 9 9b bottom surface of recess 9 O Tool body 1 axis

Claims (3)

[Claims] 1. A head portion having a vertically elongated cross section orthogonal to the axis of the tool body is formed at the tip portion of the tool body having an axial shape, and a cutting blade is provided at the tip of the head portion. A tip pocket having a bottom surface extending so as to be continuous with the rake face of the cutting edge is formed on one end side in the longitudinal direction in the cross section of the head portion, and the bottom surface of the chip pocket has a cross section in the cross section. A cutting tool having a recessed portion formed on the other end side in the longitudinal direction. 2. The recess is formed such that an opening edge of the recess to the bottom surface of the chip pocket is spaced apart from an outer peripheral edge of the bottom surface of the chip pocket. The cutting tool described. 3. The cutting tool according to claim 1, wherein the concave portion is formed so that a bottom surface thereof has a concave curved surface shape.