JP2021062430A - Hole processing method and boring tool - Google Patents

Abstract

To provide a method for realizing the efficient hole processing.SOLUTION: A hole processing method comprises the steps of: relatively rotating a processing object material 3 with respect to a boring tool; and relatively feeding the boring tool with respect to the processing object material 3 in a direction at a prescribed angle with respect to a rotation axial line of the processing object material 3 in such a state that a first cutting edge 11 and a nose cutting edge 13 are cut into the inner surface of the hole of the processing object material 3. In the feeding step, an angle formed between a line segment connecting the boundary point between the first cutting edge 11 and the nose cutting edge 13 to the nose center of the nose cutting edge 13 and a line segment connecting a point at which the nose cutting edge 13 cuts into the inner surface of the hole with the largest amount to the nose center is set to be 30 degrees or less. An angle formed by the first cutting edge 11 cutting into the processing object material 3 with respect to a surface vertical to the longitudinal direction of a shank is set to be within a prescribed range.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a hole drilling method using a boring tool and a boring tool.

Patent Document 1 discloses a vibration-proof boring tool having a shank in which a shank core member made of a high-rigidity material and a tubular member made of a soft material and having a high coefficient of thermal expansion are joined in a shrink-fitting structure. By increasing the degree of adhesion between the shank core member and the tubular member, this anti-vibration boring tool causes sliding friction due to the difference in mechanical strength against bending deformation vibration of the shank, and this friction heats the vibration energy. By converting to energy, chatter vibration generated between the anti-vibration boring tool and the workpiece is suppressed.

Japanese Unexamined Patent Publication No. 11-277308

The shank of the boring tool used for drilling holes in the work piece is cantilevered. Therefore, the deeper the hole to be machined and the longer the shank length, the lower the rigidity in the direction perpendicular to the longitudinal direction of the shank, and the self-excited vibration due to the low rigidity is likely to occur. The most problematic self-excited vibration in drilling holes with a boring tool is "regenerated chatter vibration". In the regenerated chatter vibration, the vibration generated when cutting one rotation before (one blade before with a multi-blade tool) remains as the undulations of the machined surface, and the vibration is regenerated as the fluctuation of the cutting thickness in the current cutting. Is.

FIG. 1 shows the shape of the cutting edge of the cutting edge of a conventional boring tool. In hole drilling to form a cylindrical finished surface using a boring tool, the boring tool rotates the work material with the cutting edge cut into the inner surface of the hole of the work material that is rotating relative to each other. Feed relatively in the axial direction to form a finished surface on the inner surface of the hole. In a conventional boring tool, an arc cutting edge having a nose radius R cuts the inner surface of a hole.

The regenerated chatter vibration depends on the cutting width in the direction perpendicular to the direction of the vibration mode in which the mechanical structure is likely to vibrate. In hole drilling using a drilling tool, the direction of the vibration mode is substantially perpendicular to the longitudinal direction of the shank, so that the regenerated chatter vibration depends on the cutting width in the direction substantially parallel to the longitudinal direction of the shank. In the regenerated chatter vibration, the width c (“effective cutting width”) of the machined surface cut one rotation before (one blade before with a multi-blade tool) than the current cutting width b (called “effective cutting width”) is scraped by the current cutting. (Called "reproduction width") becomes a problem, and when the effective reproduction width c is large, reproduction chatter vibration is likely to occur.

As shown in FIG. 1, when finishing the cylindrical inner surface, the feed amount f, the effective cutting width b, and the effective regeneration width c are set to
Effective regeneration width c ≒ Effective cutting width b-Feed amount f ... (Equation 1)
The relationship is approximately established.
Even when the low rigidity of the boring tool cannot be improved, the regeneration chatter vibration can be suppressed by reducing the effective cutting width c.

On the other hand, in hole drilling using a boring tool, the finished surface roughness Rth and machining efficiency are also practically important. The theoretical finished surface roughness Rth is approximately expressed by the following equation.
Rth ≒ f ² / (8 × R) ・ ・ ・ (Equation 2)
As described above, the finished surface roughness Rth is inversely proportional to the nose radius R of the arc cutting edge and is proportional to the square of the feed amount f. Among these parameters, since the feed amount f is proportional to the machining efficiency, it is not practical to reduce the feed amount f to reduce the finished surface roughness Rth. On the other hand, if an attempt is made to increase the nose radius R to reduce the finished surface roughness Rth, from (Equation 1), the effective cutting width b becomes larger and the effective regeneration width c becomes larger, resulting in a decrease in regeneration chatter stability. Connect. From the above, the conventional boring tool that drills holes in the work material with an arc cutting edge must simultaneously satisfy the three requirements of small finished surface roughness Rth, large machining efficiency (feed amount f), and high regenerated chatter stability. Was difficult.

The present disclosure has been made in view of such circumstances, and an object of the present invention is to provide a method for achieving good hole drilling and a boring tool for achieving good drilling.

In order to solve the above problems, one aspect of the present invention is a hole drilling method for drilling a hole in a work material using a boring tool, and the boring tool includes a first cutting edge and a second cutting edge. A nose cutting edge connecting the first cutting edge and the second cutting edge, and a shank are provided. The hole drilling method consists of a process of rotating the work material relative to the boring tool and rotation of the work material with the first cutting edge and the nose cutting edge cut into the inner surface of the hole of the work material. It has a step of feeding a boring tool relative to a work piece in a direction at a predetermined angle with respect to an axis line. In the feed process, a line segment connecting the boundary points of the first cutting edge and the nose cutting edge and the nose center of the nose cutting edge, and a line segment connecting the point where the nose cutting edge cuts the inner surface of the hole most and the nose center. The angle formed by the first cutting edge is set within 30 degrees, and the angle formed by the first cutting edge that cuts into the work piece is set within a predetermined range with respect to the surface perpendicular to the longitudinal direction of the shank.

Another aspect of the present invention is a boring tool. This boring tool includes a first cutting edge, a second cutting edge, a nose cutting edge connecting the first cutting edge and the second cutting edge, and a shank, and the angle of the arc of the nose cutting edge is within 40 degrees. Is set to. The angle of the line segment connecting the boundary points of the first cutting edge and the nose cutting edge and the nose center of the nose cutting edge is set within 30 degrees with respect to the surface perpendicular to the longitudinal direction of the shank, and the longitudinal direction of the shank is set. The angle formed by the first cutting edge with respect to the plane perpendicular to is set within a predetermined range.

It is a figure which shows the cutting edge shape of the cutting edge part of the conventional boring tool. It is a flowchart which shows the process of machining a hole of a work material using a boring tool. It is a figure which shows a mode that a boring tool is machining a hole of a work material. It is a figure which shows the example of the cutting edge shape of the cutting edge part of the boring tool of an Example. It is an enlarged view of an example of a cutting edge shape. It is an enlarged view of another example of a cutting edge shape. It is an enlarged view of still another example of a cutting edge shape. It is a figure which shows another example of the cutting edge shape of the cutting edge part of the boring tool of an Example.

FIG. 2 shows a process of drilling a hole in a work material using a boring tool, and FIG. 3 shows a state in which a boring tool is machined a hole in a work material. The boring tool 1 includes a shank 2 and a blade portion 10, and the blade portion 10 is provided at the shank tip portion 2a. The boring tool 1 may be a throw-away cutting tool, and the blade portion 10 may be a replaceable throw-away tip. In this case, the throw-away tip is replaceably fixed to the shank tip 2a with a screw.

Before boring, a hole 4 is formed in the work piece 3 by a drill or the like. The boring process is carried out for the purpose of improving the surface condition of the hole 4 of the work material 3 and improving the dimensional accuracy. At the start of boring, the hole drilling device (not shown) rotates the work piece 3 relative to the boring tool 1 (S1), and the blade portion is formed on the inner surface of the hole 4 of the work material 3. With the cutting edge of 10 cut, the boring tool 1 is fed relative to the work material 3 in a direction at a predetermined angle with respect to the rotation axis of the work material 3 (S2), and a hole is formed. Finish the inner surface of 4.

The "predetermined angle with respect to the rotation axis of the work material 3" is 0 degrees with respect to the rotation axis when finishing the inner surface of the cylinder of the work material 3 (that is, the rotation axis and feed of the work material 3). When finishing the inner surface of the cone of the work material 3 (the direction is parallel), the angle with respect to the rotation axis is (90 degrees-the angle of the side surface of the cone). In hole drilling using a boring tool, it is preferable to suppress regeneration chatter vibration while maintaining a small finished surface roughness Rth and a large machining efficiency.

FIG. 4 shows an example of the shape of the cutting edge of the blade portion 10 of the boring tool 1 of the embodiment. The blade portion 10 of the embodiment is used for forming a cylindrical inner surface of the work material 3, and is a nose that connects the first cutting edge 11, the second cutting edge 12, the first cutting edge 11 and the second cutting edge 12. It has a cutting edge 13. The blade portion 10 which is a throw-away insert may include a first cutting edge 11, a second cutting edge 12, and a nose cutting edge 13 at its corners. The first cutting edge 11, the second cutting edge 12, and the nose cutting edge 13 are formed on the ridge line where the rake face and the flank surface intersect, respectively.

At the time of drilling, a part of the first cutting edge 11 and at least a part of the nose cutting edge 13 cut into the relative rotating work piece 3 and are fed in the feed direction. The portion of the first cutting edge 11 to be cut into the work piece 3 may be formed in a straight line, and the nose cutting edge 13 may be formed in an arc having a nose radius R. In the feeding step, the angle formed by the first cutting edge 11 that cuts into the workpiece 3 with respect to the surface perpendicular to the longitudinal direction of the shank 2 is set within a predetermined range.

FIG. 5 shows an enlarged view of the blade edge shape of the blade portion 10 shown in FIG. In FIG. 5, the point P indicates the boundary between the nose cutting edge 13 and the first cutting edge 11, and the point Q indicates the boundary between the nose cutting edge 13 and the second cutting edge 12. The arcuate ridge line between the points P and Q is a nose cutting edge 13 having a nose radius R, and the angle of the arc of the nose cutting edge 13 may be set within 40 degrees. The boundary point P between the nose cutting edge 13 and the first cutting edge 11 may be subjected to honing treatment such as rounding the edge or performing a small chamfer in order to prevent chipping (small defects). The nose cutting edge 13 forms a finished surface.

The point S in the nose cutting edge 13 is a point at which the nose cutting edge 13 cuts the inner surface of the hole 4 of the work material 3 to the maximum when drilling a hole. The angle α formed by the line segment connecting the point P and the nose center O and the line segment connecting the point S and the nose center O is set within a predetermined range. For example, the angle α is preferably set within 30 degrees, and more preferably within 20 degrees. The angle α may be set within 15 degrees. The line segment connecting the point Q and the nose center O and the line segment connecting the point S and the nose center O form an angle β, but the angle α is preferably set smaller than the angle β. In the embodiment, the effective cutting width b can be reduced by limiting the angle α within a predetermined range.

In the cutting edge shapes shown in FIGS. 4 and 5, the first cutting edge 11 that cuts into the work piece 3 is set parallel to the surface perpendicular to the longitudinal direction of the shank 2. Here, "parallel" includes not only a completely parallel state but also a substantially parallel state, and "nearly parallel" includes a state in which there is a deviation of, for example, less than 5 degrees in the front-rear direction of the feed direction. By making the cut portion of the first cutting edge 11 parallel to the direction perpendicular to the longitudinal direction of the shank 2, that is, the direction in which the regeneration chatter vibration is generated, the cut portion of the first cutting edge 11 is made more than the boundary point P between the nose cutting edge 13 and the first cutting edge 11. A state in which the first cutting edge 11 does not exist is created on the feed direction side. Therefore, according to the cutting edge shapes shown in FIGS. 4 and 5, the effective cutting width b with respect to the feed amount f can be made smaller than that of the conventional cutting edge shape shown in FIG.
(Equation 1) Effective regeneration width c ≒ effective cutting width b-feed amount f
Therefore, the effective regeneration width c can be reduced, and therefore the regeneration chatter vibration can be suppressed.

By carrying out the feed process in which the first cutting edge 11 that cuts into the work piece 3 is parallel to the surface perpendicular to the longitudinal direction of the shank 2 in this way, as compared with the conventional hole drilling shown in FIG. It is possible to improve the regeneration chatter stability while maintaining the finished surface roughness Rth and the processing efficiency (feed amount f).

When viewed as a boring tool alone, while the angle of the arc of the nose cutting edge 13 is set within 40 degrees, the boundary point P and the nose center O with respect to the plane perpendicular to the longitudinal direction of the shank 2. The angle on the acute angle side of the line segment connecting the two may be set within 30 degrees. This angle is preferably set within 20 degrees, more preferably within 15 degrees. Further, the angle on the acute angle side formed by the first cutting edge 11 is set within a predetermined range with respect to the surface perpendicular to the longitudinal direction of the shank 2. As a result, it is possible to realize a boring tool 1 that improves the regeneration chatter stability while maintaining the finished surface roughness Rth and the machining efficiency (feed amount f).

FIG. 6 shows an enlarged view of another example of the blade edge shape of the blade portion 10. In the cutting edge shape shown in FIG. 6, the direction in which the first cutting edge 11 extends from the boundary point P with the nose cutting edge 13 is opposite to the feeding direction with respect to the surface perpendicular to the longitudinal direction of the shank 2. Tilt in the direction of retreat). As a result, the effective cutting width b can be surely reduced as compared with the cutting edge shape shown in FIG. 5, and the regeneration chatter stability can be improved. The angle γ formed by the direction in which the first cutting edge 11 extends with respect to the plane perpendicular to the longitudinal direction of the shank 2 is preferably greater than 0 degrees and less than 10 degrees.

FIG. 7 shows an enlarged view of still another example of the blade edge shape of the blade portion 10. In the cutting edge shape shown in FIG. 7, the direction in which the first cutting edge 11 extends from the boundary point P with the nose cutting edge 13 is inclined in the same direction as the feeding direction with respect to the surface perpendicular to the longitudinal direction of the shank 2. To do. As a result, the strength of the cutting edge can be improved as compared with the shape of the cutting edge shown in FIGS. 4 and 5. The angle γ formed by the direction in which the first cutting edge 11 extends with respect to the plane perpendicular to the longitudinal direction of the shank 2 is preferably within 30 degrees. Even in this case, by arranging the portion of the first cutting edge 11 that cuts into the workpiece 3 inside the virtual arc of the nose radius R drawn from the nose center O, the boring tool shown in FIG. The effective cutting width b can be made smaller than that.

FIG. 8 shows another example of the shape of the cutting edge of the cutting edge portion 10 of the boring tool 1. The blade portion 10 shown in FIG. 8 is used for forming the inner surface of the cone of the work material 3, and is a nose that connects the first cutting edge 11, the second cutting edge 12, the first cutting edge 11 and the second cutting edge 12. It has a cutting edge 13. When forming the inner surface of the cone, the feeding process of the boring tool 1 feeds the boring tool 1 relative to the rotation axis of the work piece 3 in a direction at an angle for forming the inner surface of the cone.

At the time of drilling, a part of the first cutting edge 11 and at least a part of the nose cutting edge 13 cut into the relative rotating work piece 3 and are fed in the feed direction. The portion of the first cutting edge 11 to be cut into the work piece 3 may be formed in a straight line, and the nose cutting edge 13 may be formed in an arc having a nose radius R.

In the example shown in FIG. 8, the feed amount f is set so that the effective reproduction width c becomes 0. That is, the component of the feed amount f parallel to the shank longitudinal direction = the effective cutting width b, and the regeneration chatter stability can be improved. In reality, in preparation for the finished surface not being formed according to theory due to vibration or the like, a component parallel to the shank longitudinal direction of the feed amount f <effective cutting so that the finished surface is always formed by the nose cutting edge 13. It is preferable to adjust the feed amount f so that the effective reproduction width c becomes smaller while setting the width b.

The present disclosure has been described above based on the embodiments. The techniques of the present disclosure apply to tools different from radius end mills. This embodiment is an example, and it will be understood by those skilled in the art that various modifications are possible for each of these components and combinations of each processing process, and that such modifications are also within the scope of the present disclosure. .. For example, although it has been explained that the nose cutting edge 13 is formed by an arc having a nose radius R, it may be a curve other than the arc. Further, in the embodiment, the single-blade boring tool 1 has been described, but it may be a multi-blade boring tool.

The outline of the aspects of the present disclosure is as follows. One aspect of the present disclosure is a hole drilling method for drilling a hole in a work piece using a boring tool. The boring tool includes a first cutting edge, a second cutting edge, a nose cutting edge connecting the first cutting edge and the second cutting edge, and a shank. The hole drilling method consists of a process of rotating the work material relative to the drilling tool and the rotation of the work material with the first cutting edge and the nose cutting edge cut into the inner surface of the hole of the work material. It has a step of feeding the centering tool relative to the work material in a direction at a predetermined angle with respect to the axis line, and in the feeding process, the boundary point between the first cutting edge and the nose cutting edge and the nose cutting edge. The angle between the line connecting the center of the nose and the line connecting the center of the nose with the point where the nose cutting edge cuts the inner surface of the hole most is set within 30 degrees and perpendicular to the longitudinal direction of the shank. The angle formed by the first cutting edge that cuts into the work piece may be set within a predetermined range with respect to the surface. By setting the angle of the first cutting edge with respect to the plane perpendicular to the longitudinal direction of the shank within a predetermined range, the regeneration chatter stability is improved.

The first cutting edge that cuts into the work material may be linear, and the nose cutting edge may be arcuate. The finished surface may be formed by a nose cutting edge. The first cutting edge that cuts into the work piece may be set parallel to the plane perpendicular to the longitudinal direction of the shank. The direction in which the first cutting edge extends from the boundary with the nose cutting edge may be inclined in the direction opposite to the feeding direction with respect to the plane perpendicular to the longitudinal direction of the shank.

Another aspect of the present disclosure is a boring tool comprising a first cutting edge, a second cutting edge, a nose cutting edge connecting the first cutting edge and the second cutting edge, and a shank. The angle of the arc is set within 40 degrees. The angle of the line segment connecting the boundary points of the first cutting edge and the nose cutting edge and the nose center of the nose cutting edge is set within 30 degrees with respect to the surface perpendicular to the longitudinal direction of the shank, and the longitudinal direction of the shank is set. The angle formed by the first cutting edge with respect to the plane perpendicular to is set within a predetermined range. By setting the angle of the first cutting edge with respect to the plane perpendicular to the longitudinal direction of the shank within a predetermined range, the regeneration chatter stability is improved. The first cutting edge may be linear and the nose cutting edge may be arcuate.

1 ... Boring tool, 2 ... Shank, 2a ... Shank tip, 3 ... Work material, 4 ... Hole, 10 ... Blade, 11 ... 1st cut Blade, 12 ... 2nd cutting edge, 13 ... Nose cutting edge.

Claims (7)

A hole drilling method for drilling a hole in a work material using a boring tool. The boring tool uses a first cutting edge, a second cutting edge, the first cutting edge, and the second cutting edge. Equipped with a connecting nose cutting edge and a shank,
A process of rotating the work material relative to the boring tool, and
With the first cutting edge and the nose cutting edge cut into the inner surface of the hole of the work material, with respect to the work material in a direction at a predetermined angle with respect to the rotation axis of the work material. Has a process of relatively feeding the boring tool.
A line segment connecting the boundary points of the first cutting edge and the nose cutting edge and the nose center of the nose cutting edge, and a line segment connecting the point where the nose cutting edge cuts the inner surface of the hole most and the nose center. The angle between the blade and the blade is set within 30 degrees.
The angle formed by the first cutting edge that cuts into the work piece is set within a predetermined range with respect to the surface perpendicular to the longitudinal direction of the shank.
A hole drilling method characterized by this. The first cutting edge that cuts into the work material has a linear shape, and the nose cutting edge has an arc shape.
The hole drilling method according to claim 1, wherein the hole is drilled. The finished surface is formed by the nose cutting edge.
The hole drilling method according to claim 1 or 2. The first cutting edge that cuts into the work piece is set parallel to a plane perpendicular to the longitudinal direction of the shank.
The hole drilling method according to any one of claims 1 to 3, wherein the hole is drilled. The direction in which the first cutting edge extends from the boundary point is inclined in the direction opposite to the feed direction with respect to the plane perpendicular to the longitudinal direction of the shank.
The hole drilling method according to any one of claims 1 to 3, wherein the hole is drilled. A boring tool including a first cutting edge, a second cutting edge, a nose cutting edge connecting the first cutting edge and the second cutting edge, and a shank, and the angle of the arc of the nose cutting edge is It is set within 40 degrees,
The angle formed by the line segment connecting the boundary points of the first cutting edge and the nose cutting edge and the nose center of the nose cutting edge with respect to the plane perpendicular to the longitudinal direction of the shank is set within 30 degrees. ,
The angle formed by the first cutting edge with respect to the plane perpendicular to the longitudinal direction of the shank is set within a predetermined range.
A boring tool that is characterized by that. The first cutting edge is linear,
The boring tool according to claim 6, wherein the boring tool is characterized in that.

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