JP2009095922A - Tool for processing bore diameter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool for processing a bore diameter of a small-diameter hole, which enhances rigidity of a neck section without damaging a discharge characteristic of cutting chips, having a neck section wherein one side of an end side section is ground from a rod-shaped raw material so as to project a cutting edge to one side of the end. <P>SOLUTION: One side 22 of the neck section 20 is gradually ground largely from its base end 23 toward the end 21, and a width of the neck section 20 viewed from a rake face side of the cutting edge 40 is formed to be widened from the end 21 to the base end 23 excluding a section projected to form the cutting edge 40. Then, a section modulus of the neck section 20 regarded as a cantilever receiving cutting force applied on the cutting edge 40 as a load at the time of bore diameter processing is formed to gradually become larger from end 21 toward the base end 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inner diameter machining tool, and in particular, the inner circumferential surface is cut (inner diameter machining) by turning or the like on a hole of a small part used in a hard disk of a personal computer or an OA device or an inner circumferential surface of a small cylindrical part. The present invention relates to an inner diameter machining tool (cutting tool) suitable for the above.

  This type of inner diameter machining tool includes a type in which a throwaway cutting insert (cutting edge tip) is detachably screwed to the tip of a shank (also simply referred to as a shank or holding part), or a high speed tool. One is an integrated type (hereinafter also referred to as the solid type) that is formed by integrally forming the tip (cutting edge) of a rod-shaped material (column or round bar) made of cemented carbide or cemented carbide by grinding. ing. The slow-away type has a structure in which the cutting edge tip is fixed by screwing or the like, so the tip of the inner diameter machining tool (hereinafter also simply referred to as a tool) becomes larger, so the hole diameter is smaller, especially 5 mm or less. It is not suitable for machining of small diameter holes such as On the other hand, in the solid type, there is no such problem because the cutting edge is cut from the rod-shaped material and is integrally formed. Therefore, for a hole with a small diameter of 5 mm or less. It is also suitable as a thing.

  In order to manufacture such a solid type tool for drilling small-diameter holes from a round bar material with a constant diameter (outer diameter) efficiently by grinding at a low cost, one side of the tip (one side) 1), a portion of the rod-like material at the base end of the neck portion is formed so as to form a shank portion while grinding one side of the portion near the tip so that the blade tip protrudes into a thin neck portion. In such a tool, the neck portion is inserted into the hollow hole of the work material, and the inner peripheral surface is machined at the tip of the tip. For this reason, the neck is thinly formed so as not to interfere with the inner peripheral surface during machining of the work material, and an appropriate chamfer is attached to the corner of the peripheral surface. And what is important in such inner diameter machining (cutting) is that the chips are smoothly discharged from the end face on the tool entrance side of the hollow hole of the work material (workpiece).

  FIG. 9 is a view of an example of this type of solid type tool 101 as seen from the rake face side of the cutting edge. This is made of a cemented carbide round bar, with one side (one side surface) 22 near the tip thereof ground to form the neck 20 so that the cutting edge 40 protrudes from one side 22 of the tip 21. The shank portion 10 is formed to be continuous with the base end 23. As shown in the figure, the tool 101 has an axis O1 of the neck 20 that is offset by an appropriate amount on the opposite side of the cutting edge 40 from the axis O of the shank 10. In this tool 101, the shank portion 10 is usually inserted into a hole of a cylindrical holder 121 as shown by a two-dot chain line, and a clamp screw is screwed into a screw hole drilled in the radial direction of the holder. Is clamped in such a manner that the outer peripheral surface of the shank portion 10 is pressed by the tip of the shank. And the holder clamped in this way is fixed to the tool rest of the processing machine (for example, automatic lathe) which is not shown in figure, and as shown in FIG. 10, it is used for internal diameter processing of the work material (for example, cylindrical part) W. . In the machining, a predetermined amount of cut is given to the cutting edge 40 of the tool 101, the neck portion 20 is inserted into the prepared hole, and is fed in the direction of the axis O1.

  By the way, in the machining of extremely small diameters such as an inner diameter of 5 mm or less, how to improve the discharge of chips generated during machining of the work material and how to increase the rigidity or strength of the neck of the tool itself. The point is extremely important. Among these, as for chip discharge, if the chip collides with the machined surface, gets entangled with the cutting edge, or clogs the inner peripheral surface (inside the hole), the finished surface will be damaged, That is why it is necessary to increase the discharge. On the other hand, under machining conditions in which the inner diameter of the work material is 5 mm or less, the space space that can be secured between the neck portion of the tool and the inner peripheral surface of the machining is naturally small, and accordingly, the chip discharge space is increased. It is not easy to secure. As shown in FIG. 10, in the above-described solid type tool 101, when performing inner diameter processing, one side (one side forming a flank) 22 from which the cutting edge 40 projects out of the neck portion 20, and the workpiece The gap between the material W and the inner peripheral surface W2 becomes a discharge space (hereinafter also simply referred to as a space) S for the chips K, and the chips K are discharged.

  On the other hand, in order to secure a large discharge space for such chips, the neck portion 20 of the tool 101 is narrowed. However, the thinner the neck portion is, the cutting due to the main component force at the time of cutting or the like. The stiffness of the tool against resistance is reduced. As a result, the bending deformation of the neck of the tool is increased, and chattering occurs during processing, which causes a decrease in the accuracy of the processed surface, or in some cases, breaks the tool. Such bending deformation and breakage problems are based on the fact that a lateral load is applied to the tip of the neck at the time of cutting, but it is the same as when the cantilever beam breaks due to increased bending stress and deflection. Depending on the reason. Such a problem tends to occur because the neck becomes elongated and the protruding amount increases as the machining inner diameter of the work material decreases and the machining range (hole depth) increases.

Under these circumstances, the cross section of the neck is formed into an oval shape having a major axis in a direction substantially perpendicular to the rake face of the cutting edge, thereby increasing the second moment of the neck section with respect to the minor axis, thereby increasing the strength. A conventional technique for achieving the above has also been proposed (Patent Document 1).
Japanese Utility Model Publication No. 1-242805

  As described above, in the conventional inner diameter machining tool 101 as shown in FIGS. 9 and 10, in order to prevent the machining surface accuracy from being lowered due to the reduction in chip dischargeability, the neck portion 20 is narrowed to produce chips. A tool formed to ensure the discharge space S must be used. On the other hand, in the case where there is a great demand to prevent the finished surface accuracy of the machined surface due to the occurrence of cracks or to break the tool, it is necessary to use a tool having a thick neck portion 20 and increased rigidity. Thus, in the conventional inner diameter machining tool, when machining a hole or inner peripheral surface with a small inner diameter, it is formed by selectively giving priority to either chip dischargeability or neck rigidity. Since a tool must be used, there is a problem that there is a difficulty in either of them.

  In addition, according to the technique described in Patent Document 1, since the cross section of the neck has a major axis in a direction substantially perpendicular to the rake face, the cross section of the neck is compared with that of a circular cross section. Even when the same rigidity is obtained, a large chip discharge space can be secured on the flank side of the neck. Therefore, according to the technique described in Patent Document 1, the strength can be increased as compared with a tool that can secure a similar chip discharge space on the flank side. However, based on the cross-sectional shape, the smaller the inner diameter of the work, the more difficult it is to increase the long axis. Therefore, in particular, the hole is deep with a minimum inner diameter that requires a longer neck length ( There is a problem that it is not suitable for inner diameter processing (having a long processing range).

  The present invention has been made in view of the above problems in an internal diameter machining tool for drilling a small diameter of several millimeters, and can improve the rigidity of the neck without impairing chip discharge performance. An object of the present invention is to provide an inner diameter machining tool suitable for machining a small-diameter hole.

The present invention described in claim 1 is a tool for machining an inner diameter provided with a neck at the tip of the shank and formed so that the blade edge protrudes on one side of the tip of the neck. In an inner diameter machining tool provided with a neck formed by grinding at least the one side near the tip so that the blade tip protrudes on one side of the tip,
The one side is greatly ground toward the tip from the base end of the neck, and the width when viewed from the rake face side of the blade edge, except for the portion where the neck protrudes to form the blade edge, Formed to widen from the tip to the base,
Moreover, the neck portion is formed such that the section modulus when it is regarded as a cantilever beam that receives the cutting resistance applied to the cutting edge as a load at the time of inner diameter processing is increased from the distal end toward the proximal end. And

The present invention according to claim 2 is an inner diameter machining tool provided with a neck at the tip of the shank and formed so that the blade edge protrudes on one side of the tip of the shank. In an inner diameter machining tool provided with a neck formed by grinding at least the one side near the tip so that the blade tip protrudes on one side of the tip,
The one side is greatly ground toward the tip from the base end of the neck, and the width when viewed from the rake face side of the blade edge, except for the portion where the neck protrudes to form the blade edge, Formed to widen from the tip to the base,
Moreover, the neck portion is formed such that the section modulus when it is regarded as a cantilever beam that is loaded in a direction perpendicular to the rake face with respect to the distal end increases as it goes from the distal end to the proximal end. It is characterized by that. That is,

  In the present invention, “when viewed from the rake face side of the cutting edge” means that the rake face of the cutting edge is viewed from a direction perpendicular to the rake face when the rake angle (upper rake angle) is assumed to be zero. It means when. Further, for the neck, the meaning that “the width is formed so as to increase in width from the distal end toward the proximal end” means that the width is gradually increased from the distal end toward the proximal end, and In the case where the width is gradually increased, the case where these are combined is also included.

  In addition, the invention of Claims 3-5 shows the specific example of the aspect from which the width | variety is gradually widened as it goes to a base end from a front-end | tip. The invention according to claim 3 is characterized in that one side of the neck where the cutting edge protrudes is linear except for a portion protruding so as to form the cutting edge when viewed from the rake face side. The inner diameter machining tool according to 1 or 2. In the invention of claim 4, the one side of the neck where the cutting edge protrudes is formed in an arc shape which is concave except for a portion protruding so as to form the cutting edge when viewed from the rake face side. The inner diameter machining tool according to claim 1, wherein the inner diameter machining tool is characterized by the following. Further, the invention according to claim 5 is that the one side of the neck where the blade edge protrudes is an arc shape that is convex except for a portion protruding so as to form the blade edge when viewed from the rake face side. The inner diameter machining tool according to claim 1, wherein the inner diameter machining tool is characterized by the following.

  In the invention described in claim 6, the maximum diameter of the shank portion is 2 to 8 mm, and the distance from the blade edge to the tip of the shank portion is 2.5 times or more the maximum diameter of the shank portion. Item 6. The inner diameter machining tool according to any one of Items 1 to 5. In the invention according to claim 7, the maximum diameter of the shank portion is 2 to 5 mm, and the distance from the blade edge to the tip of the shank portion is 2.5 times or more of the maximum diameter of the shank portion. It is an inner diameter processing tool according to any one of claims 1 to 5.

  According to an eighth aspect of the present invention, the base portion of the neck portion has a section modulus when the neck portion is regarded as a cantilever that is loaded perpendicularly to the rake face with respect to the tip end of the neck portion with respect to the section factor S1 of the shank portion. 8. The inner diameter machining tool according to claim 1, wherein S2 / S1, which is the ratio of the section modulus S2, is 90% or more.

  According to the present invention, the following effects can be obtained. In the present invention, the width of the neck as viewed from the rake face side of the blade edge increases from the distal end side to the proximal end side, except for a portion protruding so as to form the blade edge. The one side is ground. For this reason, when machining an inner diameter using this tool, the gap between the side surface (hereinafter also referred to as a flank) on the side of the cutting edge of the neck portion and the inner peripheral surface of the work material is Although it becomes narrower toward the base end side of the neck, the front end side toward the blade edge is widely secured. Therefore, the chips generated at the cutting edge cut into the work material are not easily entangled with the cutting edge due to the presence of the large space, flow smoothly separated from the cutting edge, and are discharged to the outside.

  What is important in the present invention is as follows. According to the results of repeated test machining by the inventors of the present application, as in the case of using the tool of the present invention, the chip discharge space is located on the flank side at the position where the neck portion is close to the vicinity of the cutting edge (site near the tip). In the case where a large space is secured, even if the space becomes narrower (decreases) toward the base end side, the chip discharge performance hardly decreases. This is the case when using the tool of the present invention, and the case where the neck is processed using a tool having the same width up to the base end while maintaining the width of the neck of the tool in the present invention in the immediate vicinity of the cutting edge. As a result of cutting and visually observing the finished surface (machined inner surface) after machining, it was found that both chips were judged good without damaging the inner surface (finished surface). .

  This means that the space on the tip side is adequately secured even if the space of the part separated from the blade edge is narrowed in the space on the one side (also referred to as the flank face) where the cutting edge in the neck protrudes. As long as it is present, it means that the chip dischargeability is not lowered. The degree of increase in the width of the neck portion is 1 when the one side is formed linearly as described in claim 3 with respect to the axis of the shank portion when viewed from the rake face side. It is preferable to set the angle so as to incline in the range of 5 to 5 degrees, preferably 1 to 3 degrees. However, if the degree of increase in the width of the neck becomes too large, the chip dischargeability is reduced, although it depends on the length of the neck and the form and properties of the chips depending on the material of the work material. Therefore, what is necessary is just to set the extent of the increase in the range without such a problem.

  On the other hand, in the tool of the present invention, the cross-section of the neck is set so that the section modulus increases as it goes from the tip to the base. For this reason, the rigidity of the neck portion of the tool of the present invention is reliably increased as compared with the conventional tool in which the neck portion is uniformly formed toward the base end with the section modulus of the tip of the present invention. Further, the bending (deformation amount) of the neck with respect to the bending moment can be reduced. In other words, the tool according to the present invention is fixed to a tool post of a processing machine such as a lathe through a holder if the shank portion is required, and the neck portion protrudes with the blade edge as a free end to process in a cantilever state. However, according to the present invention, the rigidity and strength of the neck can be reliably increased as compared with the conventional tool having the above-described configuration. Therefore, it is effective in preventing the occurrence of chatter and lowering of the finished surface accuracy due to chatter, and is also effective in preventing the reduction in tool life due to breakage. Although it can be said that the degree of increase in the section modulus is preferably proportional to the bending moment in terms of design, it is better to increase it from the viewpoint of improving rigidity.

  In addition, the section modulus of the neck is assumed to be that of a cantilever that is loaded in a direction perpendicular to the rake face with respect to the tip of the neck as described in claim 2. Design can be made easy. That is, it is mainly the magnitude of the bending moment that the strength of the neck of the tool of the present invention becomes a problem. On the other hand, when the inner diameter machining is performed in the tool of the present invention, the direction in which the cutting resistance (the resultant force) including the main component force applied to the cutting edge acts depends on the rake angle size of the rake face of the cutting edge, the cutting amount, and the like. On the other hand, in the inner diameter machining with a small diameter, even if it is assumed that the direction in which the cutting resistance (the resultant force) acts is a direction perpendicular to the rake face, it can be seen that the substantial difference is small. Therefore, as described in claim 2, the section modulus when it is regarded as a cantilever beam in which a load is applied in a direction perpendicular to the rake face with respect to the tip end of the neck portion becomes larger as it goes from the tip end toward the base end. By doing so, it is not necessary to make a difference in the rake angle or the like a problem, so that the design of the neck can be facilitated. In place of the “section modulus”, the moment of inertia of the section may be increased.

  As described above, according to the tool of the present invention, the strength of the neck can be increased without impairing chip dischargeability, so that it can be an extremely excellent tool in terms of improvement in machining surface accuracy and tool life. it can. Therefore, it can be said to be a suitable tool when machining with a small inner diameter is required, such as small precision parts.

  In the tool according to claim 4, since the projecting side of the cutting edge at the neck portion has an arc shape that is concave, the chip discharge space in the vicinity of the cutting edge can be ensured larger than the linear shape of claim 3. In addition, it is possible to further improve the chip discharging property. Therefore, the present invention is particularly suitable for a tool for machining the inner diameter of a work material having an inner peripheral surface with a small inner diameter and a deep depth (long machining range). And in the tool according to claim 5, since it has an arc shape in which the protruding side of the cutting edge at the neck is convex, the chip discharging property is low, contrary to the tool according to claim 4, It is easy to increase the strength (rigidity) of the neck. Therefore, it can be said that the tool is suitable for machining conditions having a large cutting resistance.

  In the tool according to claim 6, the maximum diameter of the shank part is 2 to 8 mm, and the distance from the blade edge to the tip of the shank part is 2.5 times or more of the maximum diameter of the shank part. The rigidity of the neck can be increased, and an inner diameter machining tool suitable for drilling a small diameter can be obtained without impairing the chip discharge performance. Furthermore, in the tool according to claim 7, the maximum diameter of the shank portion is 2 to 5 mm, and the distance from the blade edge to the tip of the shank portion is 2.5 times or more of the maximum diameter of the shank portion. As a result, the rigidity of the neck can be increased, and the inner diameter machining tool suitable for drilling a smaller diameter can be obtained without impairing the chip discharge performance.

  9. The tool according to claim 8, wherein the neck is a base end portion of the neck portion with respect to the section modulus S1 of the shank portion when the neck portion is regarded as a cantilever beam that is loaded perpendicularly to the rake face with respect to the tip end. By setting S2 / S1 which is the ratio of the section modulus S2 to 90% or more, the rigidity (rigidity) of the neck can be further increased.

  The best mode for carrying out the present invention (first embodiment) will be described with reference to FIGS. FIG. 1 is a view (plan view) of the tool as viewed from the rake face side and an enlarged view of the neck portion thereof, and FIG. 2 is a view illustrating a transverse section thereof in the enlarged view of the neck portion of FIG. 3 is a view of the tool of FIG. 1 as viewed from the flank side and an enlarged view of the neck portion thereof, and FIG. 4 is a perspective view of the neck portion including the blade edge of the tool of FIG. 1 and a tip portion including the blade edge thereof. FIG. 5 is an explanatory plan view for explaining a state in which the inner diameter is processed by the tool of FIG.

  The tool 1 of the present embodiment includes neck portions 20 that extend from both ends of the substantially columnar (maximum diameter D) shank portion 10 in the same direction as the axis O of the shank portion 10. The neck portion 20 has a smaller diameter than the shank portion 10 and is formed such that the cutting edge 40 protrudes on one side of the tip (lower side in FIG. 1). However, the inner diameter machining tool 1 is manufactured by grinding, for example, from a cemented carbide rod-shaped material (round bar having a diameter D), and in this example, a neck portion is provided at both left and right ends of the shank portion 10. 20 and the cutting edge 40 are provided, but the cutting edges 40 at both left and right end portions are formed so that the rake face 43 of the cutting edge 40 is on the opposite surface side in order to make the cutting edge the same at the time of processing. Since it is the thing of the same structure except except, it demonstrates in detail based on the one (left side of FIG. 1) below.

  That is, the neck portion 20 is formed by grinding a portion near the tip on one side (lower side in FIG. 1) 22 from which the blade tip 40 protrudes so that the blade tip 40 protrudes on one side 22 of the tip 21. . However, the one side 22 is linear so that the grinding allowance increases from the base end 23 of the neck 20 toward the cutting edge 40 of the tip 21 when viewed from the rake face 43 side of the cutting edge 40 (see FIG. 1). It is ground to make a flat surface. For this reason, the grinding allowance on this one side 22 (also referred to as one side face 22) viewed from the rake face 43 side is the grinding allowance G2 in the immediate vicinity (root) of the protruding cutting edge 40 and the tip of the shank part 10 (the neck part 20). The grinding allowance G3 in the vicinity of the base end) 11 is set as G2> G3, and the angle θ1 with respect to the axis O of the shank portion 10 viewed from the rake face 43 side is formed to be tapered at, for example, 2 degrees. Yes. However, the one side 22 may be ground so that the grinding allowance G3 at the base end 23 of the neck 20 connected to the tip 11 of the shank 10 is 0 (none). When the grinding allowance G3 is set to 0 (none) in this way, the cross section of the tip 11 of the shank portion 10 and the base end 23 of the neck portion 20 can be made the same, so that a rapid change in the cross section near the boundary is reduced. Therefore, it is possible to prevent strength reduction due to stress concentration. The grinding allowance G2 viewed from the rake face 43 side is the same as or slightly smaller than the protruding amount of the cutting edge 40.

  As described above, the neck portion 20 is ground on one side 22 except for a portion protruding so as to form the cutting edge 40 when viewed from the rake face 43 side. (1 upper side) extends on the outer peripheral surface of the shank portion 10 except that a portion 26 near the tip surface 25 is ground in an inclined manner. Thus, the neck 20 has a length from the cutting edge 40 to the tip 101 of the shank part N as N, and the width when viewed from the rake face 43 side of the cutting edge 40 is the tip portion (the position closest to the cutting edge 40 (root)). The width is L2, the width of the base end 23 is L3, and the width is linearly increased from the tip 21 toward the base end 23. The neck 20 has a cross section so that the section modulus when it is regarded as a cantilever that receives the cutting resistance applied to the cutting edge 40 as a load at the time of inner diameter processing increases from the distal end 21 toward the proximal end 23. The surface is formed as shown by hatching in FIG.

  In this example, the flat surfaces 29 that are parallel to each other and have a predetermined width are ground on the outer peripheral surfaces of the shank portion 10 and the neck portion 20 along the axis O of the shank portion 10 so as to grind a minute split circle height. It is formed with. However, the flat surface 29 extends parallel to the axis O so as to be parallel to the rake face 43 when the rake angle is regarded as zero. The flat surface 29 forms a reference surface when the tool 1 is inserted and fixed in the mounting hole of the holder. The flat surface 29 is pressed by the tip of the screw so that the circumferential direction of the shank portion 10 can be reduced. It is set so that positioning is performed, and in this example, it is formed so as to be orthogonal to the ground side surface 22. In this embodiment, as shown in FIGS. 1 to 4, the neck portion 20 has one side 22 from which the cutting edge 40 protrudes (hereinafter, a surface forming this one side is also referred to as a flank 22 in the following description). ) (See FIG. 3), from the tip 21 of the neck portion 20 to the 1/3 to 1/2 portion of the entire length of the neck portion 20, the rake face 43 side of the blade edge 40 is flat by grinding a half-section portion of the material. The flat surface 31 is parallel to the surface 29, and the rear end thereof is a concave arcuate curved surface 33 that is gently recessed to the outer peripheral surface of the intermediate portion of the neck portion 20.

  The flank 22 of the neck 20, except for the recessed portion, is located along the longitudinal direction of the neck 20 at the intersecting ridge portion of the rake face 43 and the positioning flat surface 29. A predetermined chamfer 35 is given by grinding. A predetermined chamfer 36 is also provided by grinding along the longitudinal direction of the neck portion 20 at the intersection ridge portion of the positioning flat surface 29 formed on the opposite side of the rake face 43 and the flank 22. . Such chamfers 35 and 36 are for avoiding interference and contact between the inner peripheral surface of the work material and the neck portion 20 during the inner diameter processing of the work material. The reason why the chamfering width decreases toward the front end side is that the width of the neck 20 when viewed from the rake face 43 side is narrower toward the front end side as shown in FIG. Since the neck 20 is formed by grinding a round bar material having a constant diameter as described above, the neck 20 moves from the distal end 21 toward the proximal end 23 except for the protruding cutting edge 40. The section modulus is large.

  The blade edge 40 protrudes in a triangular shape when viewed from the rake face 43 side at the tip 21 of the neck portion 20 as shown in the enlarged view of FIG. As described above, the surface is made low through the breaker step 45, and this low surface is the actual rake face 43 of the cutting edge 40, and a slight rake angle is given in this example. The width of the tool 1 at the tip of the protruding cutting edge 40 when viewed from the rake face 43 side is formed by grinding the round bar (column) material by the tool 1. It is smaller than the width of the shank portion 10 (the outer diameter of the round bar material). As shown in the enlarged view of FIG. 4, the flank face 42 side of the blade edge 40 is separated from the rake face 43 at the boundary between the flank face 42 of the protruding blade edge 40 and the flank face 22 forming one side of the neck 20. As a result, the clearance angle of one side surface (flank surface) 22 of the neck portion 20 on the side where the blade edge 40 protrudes is 0 °, while the clearance angle 0 of the neck portion 20 is 0 °. This is because a clearance angle is given. Of the protruding cutting edge 40, a chamfer 47 is provided on the side opposite to the rake face 43 (the lower side in FIG. 3) over the tip face 25 of the neck portion 20, and the inside of the work piece at the time of machining is provided. It is set as the structure by which interference with a surrounding surface is avoided.

  In addition, as shown in FIG. 6, the neck portion has a section modulus when the neck portion is considered to be a cantilever that is loaded in a direction perpendicular to the rake face with respect to the tip, and the section factor S1 of the shank portion is based on the neck portion. The section modulus S2 of the end portion is configured to be 90% or more.

  Therefore, in the case of machining the inside diameter of a work material having a small inside diameter with such a cutting tool 1, the following operational effects can be obtained. That is, as shown in FIG. 5, when machining the inner diameter of the work material W using this tool 1, the side surface (flank) 22 on the side of the neck portion 20 from which the cutting edge 40 projects, The space S between the inner peripheral surface W2 of the cutting material W has a width when the neck portion 20 is viewed from the rake face side, and the base end side is narrowed by the inclination angle θ1 attached to the one side face 22. Yes. On the other hand, the space S on the distal end side toward the cutting edge 40 is G2 at the maximum due to the existence of the inclination angle θ1 (2 degrees), and is secured wider than the proximal end side. That is, when the inner peripheral surface W2 of the work material W is machined by, for example, a cylindrical inner peripheral surface with a constant cut with the cutting tool 1, between the inner peripheral surface W2 and the flank 22 at the neck 20 of the tool 1. As compared with the portion near the base end of the neck portion 20, the tip discharge portion S is secured larger by the inclination angle θ1. Thereby, as shown in FIG. 5, the chips K generated during the processing do not get entangled with the cutting edge 40 due to the presence of a large space S near the tip 21 of the neck portion 20. 1 It discharges outside from the inlet side end face. As described above, the space of the neck portion 20 on the flank 22 side away from the cutting edge 40 has a smaller space at the inclination angle θ1, but the space S in the vicinity of the cutting edge 40 is smaller. Is sufficiently secured to form a pocket, so that even if the space S on the side of the flank 22 gradually decreases by 2 degrees toward the base end 23, it prevents a reduction in chip discharge that becomes a problem. it can. This is supported by the fact that there is no generation of scratches that cause problems on the processed inner peripheral surface after processing and no reduction in surface roughness.

  On the other hand, when the neck 20 is regarded as a cantilever that receives the cutting resistance applied to the cutting edge 40 as a load at the time of inner diameter machining, the cross section of the neck 20 is increased so as to increase from the distal end 21 toward the proximal end 23. A surface is formed. For this reason, compared with the conventional tool in which the neck part 20 is uniformly formed in the cross section in the front-end | tip of the tool 1 of this example, rigidity is high. Therefore, the bending due to the bending moment of the neck 20 generated during processing can be reduced. That is, according to the tool 1 of this embodiment, the rigidity or strength can be reliably increased as compared with such a conventional tool. As a result, it is possible to prevent chattering and deterioration of finished surface accuracy due to chattering, and also to reduce tool life due to breakage.

  FIG. 7 shows another example in which the inner diameter machining tool 2 according to the present invention is embodied. In this embodiment, the neck portion 20 in the above-described embodiment has a rake face 43 on one side 22 from which the cutting edge 40 protrudes. When viewed from the side, except for the portion protruding so as to form the cutting edge 40, the shape is linear, but the only difference is that the shape is a gentle arc that is concave with a predetermined radius R1. Therefore, the same parts are denoted by the same reference numerals and the description thereof is omitted.

  Based on the said structure, this thing can ensure large chip discharge space in the site | part near the front-end | tip among the flank 22 of the neck part 20 at the time of internal diameter processing of a workpiece. Therefore, since chip | tip discharge | emission property can be improved more, it is suitable for the tool 2 for the internal diameter process of the workpiece which has an internal peripheral surface with a small internal diameter and a deep back.

  FIG. 8 shows still another example in which the inner diameter machining tool 3 according to the present invention is embodied. In contrast to the above-described embodiment, this one has a side on which the cutting edge 40 of the neck portion 20 protrudes. The only difference is that the shape is a gentle arc that is convex with a predetermined radius R2 when viewed from the rake face 43 side. Therefore, also about this, the same code | symbol is attached | subjected to the same site | part and the description is abbreviate | omitted. From this configuration, it can be said that the strength (rigidity) of the neck portion 20 is easily increased, and therefore, it can be said that it is suitable for processing conditions in which cutting depth is small but cutting resistance is increased.

  The present invention is not limited to the examples described above, and can be embodied with appropriate modifications. Since the neck can be considered to resist the same bending moment as a cantilever beam that receives a load at its tip during processing, it is preferable to design the section modulus to increase in proportion to the bending moment. However, as described above, in the present invention, it is only necessary that the section modulus on the base end side is larger than the tip end. The section modulus is such that when the neck is regarded as a cantilever that is loaded in a direction perpendicular to the rake face with respect to the tip, the section modulus increases as it goes from the tip to the base end. , You can set. In addition, as described above, the neck may be configured such that the secondary moment of section related to the neutral axis caused by bending during inner diameter processing (when receiving cutting force) increases from the distal end toward the proximal end.

  In the above example, the inner diameter machining tool is embodied as a boring tool. However, the inner diameter machining tool can be embodied similarly in a grooving tool or a screwing tool. Moreover, about the aspect of the grinding | polishing in formation and manufacture of a tool, it can materialize as an appropriate thing according to the length of a neck part and the processing conditions requested | required of a tool. Furthermore, the outer diameter (width and extent of change) and length of the neck are appropriately determined according to the work conditions such as the material of the work, the depth of the inner peripheral surface (hole) to be processed, and the hole diameter. You only have to set it.

The figure (plan view) which looked at the 1st example of an inner diameter processing tool of the present invention from the rake side, and the enlarged drawing of the neck. The figure explaining the cross section in the enlarged view of the neck of FIG. The figure which looked at the tool for internal diameter processing of FIG. 1 from the flank side, and the enlarged view of the neck part. The perspective view of the neck part containing the blade edge | tip of the tool of FIG. 1, and the enlarged view of the front-end | tip part containing the blade edge | tip. FIG. 2 is an explanatory plan view for explaining a state in which inner diameter machining is performed with the tool of FIG. 1. The figure explaining an example by which the section coefficient of the base end part of a neck is comprised 90% or more with respect to the section coefficient of a shank part. The enlarged view of the neck part seen from the rake face side explaining another embodiment example (modification) of the internal diameter processing tool of this invention. The enlarged view of the neck part seen from the rake face side explaining another embodiment example (modification) of the internal diameter processing tool of this invention. The figure which looked at the conventional solid type inner diameter processing tool from the rake face side of the cutting edge. FIG. 10 is an explanatory plan view for explaining a state where the inner diameter is processed by the tool of FIG. 9 and an enlarged view for explaining the main part thereof.

Explanation of symbols

1, 2, 3 Internal diameter machining tool 10 Shank part 11 Shank part tip 20 Neck part 21 Neck part tip 22 One side 23 where the blade edge of the neck is ground 23 Neck base edge 40 Cutting edge G2, G3 Neck width

Claims (8)

An inner diameter machining tool provided with a neck at the tip of the shank, and a blade tip protruding from one side of the tip of the neck, the blade tip protruding from one side of the tip from a rod-shaped material In addition, in an inner diameter machining tool comprising a neck portion that is ground on at least one side of the portion near the tip,
The one side is greatly ground toward the tip from the base end of the neck, and the width when viewed from the rake face side of the blade edge, except for the portion where the neck protrudes to form the blade edge, Formed to widen from the tip to the base,
Moreover, the neck portion is formed such that the section modulus when it is regarded as a cantilever beam that receives the cutting resistance applied to the cutting edge as a load at the time of inner diameter processing is increased from the distal end toward the proximal end. Internal diameter machining tool.   The neck portion is formed such that a section modulus when it is regarded as a cantilever beam that is loaded in a direction perpendicular to the rake face with respect to the distal end thereof is increased from the distal end toward the proximal end. The inner diameter machining tool according to claim 1, wherein   3. The inner diameter according to claim 1, wherein one side of the neck where the blade edge protrudes is linear except for a portion protruding so as to form the blade edge when viewed from the rake face side. Tool for processing.   The one side where the said blade edge | tip protrudes in the said neck part is made into the circular arc shape which becomes concave except for the site | part which protrudes so that it may make this blade edge | edge, seeing from the rake face side. The inner diameter machining tool described.   The one side where the said blade edge protrudes in the said neck part is made into the circular arc shape which becomes convex except for the site | part which protrudes so that this blade edge may be made seeing from the rake face side. The inner diameter machining tool described.   The maximum diameter of the shank part is 2 to 8 mm, and the distance from the cutting edge to the tip of the shank part is at least 2.5 times the maximum diameter of the shank part. The inner diameter machining tool described in 1.   The maximum diameter of the shank part is 2 to 5 mm, and the distance from the blade edge to the tip of the shank part is at least 2.5 times the maximum diameter of the shank part. The inner diameter machining tool described in 1.   The section modulus when the neck portion is regarded as a cantilever beam loaded perpendicularly to the rake face with respect to the tip is a ratio of the section modulus S2 of the proximal end portion of the neck portion to the section modulus S1 of the shank portion. S2 / S1 is 90% or more, The internal diameter processing tool of any one of Claims 1-7 characterized by the above-mentioned.

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