JP7477308B2 - Shank for cutting tool, cutting tool and cutting method - Google Patents

Description

Embodiments of the present invention relate to a shank for a cutting tool, a cutting tool, and a cutting method.

A method is known in which a cutting tool such as a drill or reamer is attached to a handheld tool rotating device to perform cutting work such as drilling (see, for example, Patent Document 1). A typical handheld tool rotating device is provided with a chuck, and the shank of a cutting tool such as a drill or reamer is held in the chuck of the tool rotating device in an exchangeable manner.

Among tooling systems consisting of a shank and a chuck, a shank and a chuck with a simple structure that allows cutting tools to be replaced with as few setups as possible is known (see, for example, Non-Patent Document 1). This shank and chuck are marketed under the names of quick-change shanks and chucks for quick-change shanks.

There are two types of quick-change shanks and chucks for quick-change shanks: A-TYPE and B-TYPE. A-TYPE is designed for normal cutting work, and A-TYPE quick-change shanks and chucks are sold as QA shanks and QA chucks, respectively. On the other hand, B-TYPE is designed for cutting work in narrow spaces, and B-TYPE quick-change shanks and chucks are sold as QB shanks and QB chucks, respectively.

Figure 11 is a front view of a conventional QA shank, and Figure 12 is a cross-sectional view at the position of three blind holes formed radially on the side of the conventional QA shank shown in Figure 11.

As shown in Figures 11 and 12, the shape, including the dimensions, of the QA shank, which is an A-TYPE quick change shank, is standardized. Specifically, the QA shank has a shape in which an annular groove is provided on the side of a cylinder with the length direction being the circumferential direction of the cylinder, and three equally spaced blind holes are provided on the bottom surface of the annular groove with the depth direction being the radial direction of the cylinder.

A QA shank with this shape can be attached to and detached from a QA chuck equipped with three steel balls. In other words, the three steel balls arranged at the vertices of an equilateral triangle are slid radially along the QA shank, and the three steel balls are inserted and removed from the three blind holes formed in the QA shank, thereby allowing the QA shank to be attached to and detached from the QA chuck.

While a typical chuck needs to rotate to hold the tool, the QA chuck can easily attach and detach the QA shank by simply sliding a member that slides lengthwise, like an air coupler, to change the position of the steel ball.

Figure 13 is a front view of a conventional QB shank.

As shown in Figure 13, the shape, including the dimensions, of the QB shank, which is a B-TYPE quick change shank, is also standardized. The length of the QB shank is shorter than the length of the QA shank. Therefore, the distance from the end face of each central axis of the three blind holes provided in the QB shank is also shorter than the distance from the end face of each central axis of the three blind holes provided in the QA shank. Other than the length of the QB shank and the positions of the three blind holes in the longitudinal direction of the QB shank, the shape of the QB shank is the same as that of the QA shank.

Because the length of the QB shank is shorter than the length of the QA shank, the length of the QB chuck is also shorter than the length of the QA chuck. Therefore, the short QB chuck can be used as a typical corner drill holder. In other words, the QB shank and QB chuck can be used as a shank and chuck for cutting in narrow areas.

Japanese Utility Model Application Publication No. 2002-135108

, [Retrieved July 18, 2019], Internet <URL: http://www.magnavon.com/catalog/quick>, MAGNAVON INDUSTRIES Catalog

However, the QA shank cannot be attached to or detached from the QB chuck. This is because the length of the QA shank is longer than the depth of the insertion hole of the QB chuck, and it cannot be inserted into the QB chuck up to the position of the blind hole of the QA shank. Conversely, if a short QB shank is attached to a QA chuck, the rigidity becomes insufficient and the vibration range of the cutting tool increases. As a result, the cutting tool may chip or break, and the machining quality of the workpiece may deteriorate significantly.

Therefore, it is necessary to attach the QA shank to a QA chuck and the QB shank to a QB chuck when using them. Furthermore, when performing cutting processing by attaching a cutting tool such as a drill to a typical tool rotating device, performing cutting processing under processing conditions that result in greater cutting resistance leads to improved processing efficiency compared to when a cutting tool is attached to a corner drill or the like and localized cutting processing is performed, so it is preferable to attach the cutting tool to the tool rotating device using a QA shank with ensured rigidity. In other words, using a QB shank and QB chuck to perform all types of cutting processing is not preferable from the perspective of improving processing efficiency.

For this reason, when cutting narrow areas where cutting must be performed under conditions that reduce cutting resistance, and when cutting non-narrow areas where cutting should be performed under conditions that increase cutting resistance, it is necessary to prepare both a cutting tool with a compact QB shank and a cutting tool with a highly rigid QA shank.

The present invention aims to make it possible to easily attach and detach a cutting tool to a handheld tool rotation device, while enabling cutting processes such as drilling and reaming to be performed with a common cutting tool regardless of whether the area is narrow or not.

A cutting tool shank according to an embodiment of the present invention is a cylindrical or columnar cutting tool shank for holding a cutting tool body in a chuck of a tool rotation device. The cutting tool shank has a joint portion having a blind hole having a depth of 5 mm or more into which an end portion of the body is inserted and brazed , and a holding portion that is integrated with the joint portion and is used for holding the cutting tool in the chuck.
The holding portion has a first attachment/detachment structure formed at a first position 10.9 mm away from the end face on the chuck side in the longitudinal direction of the shank, for attaching and detaching to a first chuck, and a second attachment/detachment structure formed at a second position 3.3 mm away from the end face on the chuck side in the longitudinal direction of the shank, for attaching and detaching to a second chuck having a shorter shank insertion length than the first chuck .
Furthermore, the first attachment/detachment structure has a first annular recess that is deepest at the first position and whose length direction is the circumferential direction of the shank, so that the first attachment/detachment structure can be attached to and detached from the first chuck having a structure that holds the shank with first three spheres movably arranged at the three vertices of an equilateral triangle, and first three blind holes whose depth direction is the radial direction of the shank and whose central axes are equally spaced with an angular difference of 120° on a first plane that is perpendicular to the length direction of the shank at the first position.
On the other hand, the second attachment/detachment structure has a second annular recess that is deepest at the second position and whose length direction is the circumferential direction of the shank, so that the second attachment/detachment structure can be attached to and detached from the second chuck having a structure that holds the shank with three second spheres movably arranged at the three vertices of an equilateral triangle, and three second blind holes whose depth direction is the radial direction of the shank and whose central axes are equally spaced with an angular difference of 120° on a second plane that is perpendicular to the length direction of the shank at the second position.
The total length of the shank, which is the sum of the length of the joint portion and the length of the holding portion, is set to 19 mm or more and 28 mm or less.

In addition, a cutting tool according to an embodiment of the present invention has the above-mentioned shank, a cutting edge at its tip, and a body to which the shank is brazed at its rear end, and the range in which the brazing is performed is a range of 5 mm or more in the longitudinal direction of the shank .

The cutting method according to the embodiment of the present invention produces a finished product or semi-finished product by cutting a workpiece with the above-mentioned cutting tool.

1 is a front view of a drill as an example of a cutting tool having a shank according to a first embodiment of the present invention. FIG. 2 is a left side view showing the shape of the cutting edge of the drill shown in FIG. 1 . FIG. 2 is a cross-sectional view including an example of detailed dimensions in a section including a central axis of a blind hole provided in the shank of the drill shown in FIG. 1 . FIG. 2 is a diagram showing an example of detailed dimensions of the shank shown in FIG. 1 . FIG. 2 is a diagram showing another example of detailed dimensions of the shank shown in FIG. 1 . FIG. 13 is a front view of a drill as an example of a cutting tool having a shank according to a second embodiment. FIG. 13 is a projection view showing a first example shape of a cutting edge of a drill as an example of a cutting tool having a shank according to a third embodiment. FIG. 13 is a projection view showing a second example shape of a cutting edge of a drill as an example of a cutting tool having a shank according to a third embodiment. FIG. 13 is a projection view showing a third example shape of a cutting edge of a drill as an example of a cutting tool having a shank according to the third embodiment. FIG. 13 is a projection view showing a fourth example shape of the cutting edge of a drill as an example of a cutting tool having a shank according to the third embodiment. FIG. 2 is a front view of a conventional QA shank. 12 is a cross-sectional view of the conventional QA shank shown in FIG. 11 at the location of three blind holes formed radially in the side surface. FIG. 2 is a front view of a conventional QB shank.

The shank for a cutting tool, the cutting tool, and the cutting method according to the embodiment of the present invention will be described with reference to the attached drawings.

First Embodiment
(Configuration and Function)
FIG. 1 is a front view of a drill as an example of a cutting tool having a shank in a first embodiment of the present invention, FIG. 2 is a left side view showing the shape of the cutting edge of the drill shown in FIG. 1, FIG. 3 is a cross-sectional view including an example of detailed dimensions in a cross section including the central axis of a blind hole provided in the shank of the drill shown in FIG. 1, and FIG. 4 is a diagram showing an example of detailed dimensions of the shank shown in FIG. 1.

The drill 1, which is an example of a cutting tool, is composed of a body 2 and a shank 3. Both the body 2 and the shank 3 can be composed of a desired material, such as steel, such as die steel or high-speed steel, or carbide, depending on the material of the workpiece. Of course, they may be coated with diamond or the like.

A cutting edge 4 is provided at the tip of the body 2. Meanwhile, a shank 3 is joined to the rear end of the body 2. The shank 3 is a cylindrical or columnar component for holding the body 2 of the drill 1, which is an example of a cutting tool, in a chuck of a tool rotation device, such as a hand-held type.

Therefore, a joint 5 for joining the end of the body 2 is provided at one end of the shank 3, and a holding portion 6 for holding the shank 3 in a chuck of a tool rotation device is provided at the other end of the shank 3. The joint 5 and holding portion 6 are integrated to form the shank 3.

When joining the end of the body 2 to the shank 3 by brazing the rear end of the body 2 to the shank 3, a blind hole 5A is provided in the joint 5 for inserting the end of the body 2 for brazing. In other words, the joint 5 of the shank 3 has a hollow cylindrical structure with an open end on the body 2 side and a closed end on the holding part 6 and chuck side.

On the other hand, the holding portion 6 of the shank 3 has a structure that allows it to be attached and detached to both the QA chuck, which is an example of a first chuck, and the QB chuck, which is an example of a second chuck. That is, the holding portion 6 of the shank 3 has a first attachment/detachment structure 7A for attaching and detaching to the QA chuck, and a second attachment/detachment structure 7B for attaching and detaching to the QB chuck.

The first detachable structure 7A is formed at a first position P1 that is a first distance D1 away from the end face on the QA chuck side in the longitudinal direction of the shank 3. On the other hand, the second detachable structure 7B is formed at a second position P2 that is a second distance D2, which is shorter than the first distance D1, away from the end face on the QB chuck side in the longitudinal direction of the shank 3. This is because the length by which the shank 3 is inserted into the QB chuck is shorter than the length by which the shank 3 is inserted into the QA chuck.

The QA chuck has a structure that holds the shank with three spheres movably positioned at the three vertices of an equilateral triangle. Therefore, in order to make it possible to attach and detach the holding part 6 of the shank 3 to the QA chuck, it is necessary to provide the holding part 6 of the shank 3 with a structure similar to that of the conventional QA shank shown in Figure 11.

Specifically, as the first attachment/detachment structure 7A for attaching and detaching the shank 3 to the QA chuck, it is necessary to provide the holding part 6 with a first annular recess 8A that is deepest at a first position P1 that is a first distance D1 away from the end face on the QA chuck side in the longitudinal direction of the shank 3 and whose longitudinal direction is the circumferential direction of the shank 3, as shown in the figure, and first three blind holes 9A whose respective depth directions are in the radial direction of the shank 3 and whose central axes are equally spaced with an angular difference of 120° on a first plane perpendicular to the longitudinal direction of the shank 3 at the first position P1.

Similarly, the QB chuck also has a structure that holds the shank with three spheres movably positioned at the three vertices of an equilateral triangle. Therefore, in order to make it possible to attach and detach the holding portion 6 of the shank 3 to the QB chuck, it is necessary to provide the holding portion 6 of the shank 3 with a structure similar to that of the conventional QB shank shown in FIG. 13.

Specifically, as the second attachment/detachment structure 7B for attaching and detaching the shank 3 to the QB chuck, it is necessary to provide the retaining portion 6 with a second annular recess 8B formed so that it is deepest at a second position P2 that is a second distance D2 away from the end face on the QB chuck side in the longitudinal direction of the shank 3 and whose longitudinal direction is the circumferential direction of the shank 3, as shown in the figure, and second three blind holes 9B whose respective depth directions are in the radial direction of the shank 3 and whose central axes are equally spaced with an angular difference of 120° on a second plane perpendicular to the longitudinal direction of the shank 3 at the second position P2.

Note that FIG. 3 shows the shapes of both a cross section including the central axis of each of the first three blind holes 9A and a cross section including the central axis of each of the second three blind holes 9B. In the illustrated example, the positions of the second three blind holes 9B are positions obtained by translating the positions of the first three blind holes 9A in the direction of the central axis of the shank 3 from the viewpoint of ease of manufacturing, but functionally, the positions of the first three blind holes 9A and the second three blind holes 9B can be determined so that they are positions obtained by relatively translating the positions in the direction of the central axis of the shank 3 and relatively rotating the positions around the central axis of the shank 3.

The first distance D1 between the first position P1 where the first annular recess 8A and the first three blind holes 9A are formed and the end face of the shank 3 on the QA chuck side is 10.9 mm, as in the conventional QA shank, as shown in FIG. 4. On the other hand, the second distance D2 between the second position P2 where the second annular recess 8B and the second three blind holes 9B are formed and the end face of the shank 3 on the QB chuck side is 3.3 mm, as in the conventional QB shank, as shown in FIG. 4.

The overall length L of the shank 3 is the sum of the length L1 of the joint 5 and the length L2 of the retaining portion 6. In the retaining portion 6, the first annular recess 8A and the first three blind holes 9A are formed at a first position P1 that is a first distance D1 = 10.9 mm away from the end face of the shank 3, while the second annular recess 8B and the second three blind holes 9B are formed at a second position P2 that is a second distance D2 = 3.3 mm away from the end face of the shank 3. Therefore, the length L2 of the retaining portion 6 is at least the first distance D1 = 10.9 mm plus the width of a portion of the first annular recess 8A. On the other hand, it is essential that the length L1 of the joint 5 is at least the length necessary to join the end of the body 2 with sufficient strength.

Therefore, in order to evaluate the joint strength between the drill body and shank, tests were conducted in which torque was applied using a torque tester to a prototype of Drill 1, a drill equipped with a conventional QA shank as shown in Figure 11, and a drill equipped with a conventional QB shank as shown in Figure 13. As a result, it was confirmed that although the brazing length of the conventional QA shank is longer than the brazing length of the conventional QB shank, if at least the brazing length of the QB shank can be secured, the joint strength between the drill body and shank is sufficient, and that when torque is applied to the tip of the drill using a torque tester, the drill body breaks before the brazing part of the shank or the shank slips in the chuck.

Therefore, if at least the brazing length of the conventional QB shank can be secured, it is believed that the end of the body 2 can be joined with sufficient strength even if the length of the shank 3 shown in Figure 1 is longer than the length of the conventional QB shank. The brazing length in the tool axis AX direction of the conventional QB shank is 5 mm.

The shank 3 shown in FIG. 1 can be joined to the body 2 by brazing using a brazing material such as silver solder, and a blind hole 5A for brazing the end of the body 2 can be provided in the joint 5 of the shank 3 with a depth LD of 5 mm or more. This makes it possible to ensure that the range in which brazing is performed between the rear end of the body 2 and the joint 5 of the shank 3 is 5 mm or more in the length direction of the shank 3, and sufficient joint strength can be ensured for rotary cutting.

In this case, the length L1 of the joint 5 is long enough to ensure the thickness of the bottom surface of the blind hole 5A, which is at least 5 mm deep. Therefore, as shown in FIG. 4, the overall length L of the shank 3 can be determined to be 19 mm so that the joint strength with the body 2 can be ensured and the shank 3 can be attached to and detached from both the QA chuck and the QB chuck.

In this case, when the shank 3 is set in the QA chuck and the QB chuck, the protruding length of the shank 3 from the QA chuck and the QB chuck is shortened, which is advantageous from the viewpoint of avoiding interference with the workpiece when drilling holes in narrow areas. In other words, the protruding length of the drill 1 including the shank 3 from the QA chuck and the QB chuck can be shortened, making it less likely to interfere with the workpiece. For this reason, the minimum length L of the entire shank 3 is 19 mm, as shown in FIG. 4.

On the other hand, as a result of a prototype test in which the overall length L of the shank 3 was changed, it was confirmed that the swing width of the cutting edge 4 increases when the overall length L of the shank 3 is shortened, as shown in Table 1.

Specifically, the drill bodies were brazed to a conventional QB shank with a length of approximately 10 mm, the shank 3 shown in Figure 4 with a length of 19 mm, the shank 3 shown in Figure 1 with a length of 24 mm, and a conventional QA shank with a length of 28 mm so that the protruding length from the shank was 85 mm, and then set in the drill press, and the runout width at the tip of each drill was measured with a dial gauge.

As a result, as shown in Table 1, the runout width was 1.7 mm for the conventional QB shank with a length of 10 mm, 0.8 mm for the shank 3 with a length of 19 mm, 0.6 mm for the shank 3 with a length of 24 mm, and 0.5 mm for the conventional QA shank with a length of 28 mm.

Therefore, when cutting is performed with a drill 1 equipped with a shank 3 having a length L of 19 mm as shown in FIG. 4 under cutting conditions that generate the same cutting resistance as a drill equipped with a conventional QA shank, the vibration range of the cutting edge 4 becomes larger than when cutting is performed with a drill equipped with a conventional QA shank. When the vibration range of the cutting edge 4 becomes larger, the risk of chipping of the cutting edge 4 increases.

For this reason, from the perspective of reducing the risk of chipping of the cutting edge 4 to the same extent as with drills equipped with conventional QA shanks and ensuring tool life, it is considered appropriate to set the length L of the shank 3 to 28 mm, the same as the length of the QA shank.

Figure 5 shows another example of detailed dimensions of the shank 3 shown in Figure 1.

Figure 4 shows an example in which the length L of the shank 3 is set to the minimum length of 19 mm, while Figure 5 shows an example in which the length L of the shank 3 is set to 28 mm to match the length of a conventional QA shank so as to reduce the runout width of the cutting edge 4 and reduce the risk of chipping. As illustrated in Figure 4, if the length L of the shank 3 is set to 19 mm, interference with the workpiece is less likely to occur, while if the length L of the shank 3 is set to 28 mm as illustrated in Figure 5, the risk of chipping of the cutting edge 4 can be reduced.

The length L of the shank 3 may be between 19 mm and 28 mm, and a balance may be achieved between avoiding interference with the workpiece and reducing the risk of chipping the cutting edge 4 depending on the importance of each. Therefore, the length L of the entire shank 3 may be in the range of 19 mm to 28 mm. If the length L of the shank 3 is made longer than 19 mm, the depth LD of the blind hole 5A may be made deeper than 5 mm by the amount of the increase in the length L of the shank 3 to improve the joining strength of the body 2 by brazing, or conversely, the depth LD of the blind hole 5A may be set to 5 mm to reduce the labor required for brazing.

On the other hand, by optimizing not only the overall length L of the shank 3 but also the shape of the cutting edge 4, the risk of chipping of the cutting edge 4 can be reduced and the tool life can be increased. In other words, if the risk of chipping of the cutting edge 4 is reduced by optimizing the shape of the cutting edge 4, an increase in the risk of chipping of the cutting edge 4 can be suppressed even if the overall length L of the shank 3 is shortened.

As a specific example, as illustrated in Figures 1 and 2, the tip angle of the cutting edge 4 can be greater than 0° and less than 180° at the tip, and can decrease continuously from the tip side toward the rear end. On the other hand, the clearance angle of the cutting edge 4, which is the angle between the clearance face 10 of the cutting edge 4 and the surface of the workpiece after cutting, can be decreased continuously from the tip side toward the rear end, and the shape of the cutting edge 4 can be designed so that the clearance angle is formed at the maximum diameter position of the cutting edge 4.

The drill 1 can then drill holes in workpieces made of either fiber-reinforced plastics (FRP) such as glass fiber reinforced plastics (GFRP) or carbon fiber reinforced plastics (CFRP) or metal. In other words, by drilling holes in a workpiece made of at least one of metal and FRP with the drill 1, it is possible to manufacture a product or semi-finished product with holes of good quality. FRP is also called a composite material.

The mechanism is as follows. When the tip angle of the cutting edge 4 of a drill 1 in which the tip angle at the tip of the cutting edge 4 is greater than 0° and less than 180°, i.e., a drill 1 that is not a flat drill or a candle sharpening drill, is continuously reduced toward the rear end in the direction of the tool axis AX, the corners that are prone to chipping do not occur on the ridges of the cutting edge 4, thereby reducing the risk of chipping.

In addition, the occurrence of delamination (interlayer peeling) can be reduced when drilling FRP. This is because even if delamination occurs temporarily when drilling FRP with the cutting edge 4 with a relatively large tip angle at the tip side of the drill 1, the cutting resistance is reduced when drilling with the cutting edge 4 with a relatively small tip angle at the rear, and the delamination is removed.

In addition, the closer the shape of the ridgeline of the cutting edge 4 on a projection plane parallel to the tool axis AX is to a parabola, the more uniform the volume of the workpiece cut by the ridgeline per unit length in the direction of the tool axis AX becomes. This has the effect of making the cutting resistance uniform across the entire cutting edge 4. If the cutting resistance can be made uniform across the entire cutting edge 4, it is possible to reduce wear on the cutting edge 4 as well as prevent delamination and burrs when drilling FRP.

On the other hand, if the shape of the ridge of the cutting edge 4 on the projection plane parallel to the tool axis AX is made closer to an ellipse, the volume of the workpiece cut by the ridge per unit length in the direction of the tool axis AX can be reduced at a constant rate toward the rear of the cutting edge 4. This avoids a situation in which wear at the rear of the cutting edge 4, where the cutting speed is relatively fast due to a different rotation radius, progresses faster than wear at the front of the cutting edge 4, where the cutting speed is relatively slow, and has the effect of making the degree of wear progression uniform across the entire cutting edge 4. If the degree of wear progression across the entire cutting edge 4 can be made uniform, the life of the cutting edge 4 can be improved.

Therefore, depending on the effect that is emphasized, the shape of the ridge of the cutting edge 4 on the projection surface can be made to approximate a parabola or an ellipse. Of course, the shape of the ridge of the cutting edge 4 can also be determined so that one part on the projection surface is shaped like an ellipse and another part is shaped like a parabola.

If the shape of the ridge of the cutting edge 4 on the projection plane parallel to the tool axis AX is a parabola or an ellipse, the tip angle at the tip of the cutting edge 4 will be 180°, so it is necessary to determine the shape of the ridge of the cutting edge 4 so that the tip angle at the tip of the cutting edge 4 is formed at an angle that is favorable for drilling a hole in the workpiece. Therefore, for example, as illustrated in Figure 1, the shape of the ridge of the cutting edge 4 can be determined so that only the tip of the ridge of the cutting edge 4 becomes a straight line on the projection plane.

On the other hand, gradually decreasing the clearance angle of the cutting edge 4 has the effect of improving the wear resistance of the cutting edge 4. This is because if the clearance angle of the cutting edge 4 is continuously and smoothly decreased, corners that are prone to wear do not occur on the clearance surface of the cutting edge 4. Also, if a clearance angle is formed at the maximum diameter position of the cutting edge 4 where the tip angle is 0°, the cutting edge 4 at the maximum diameter position hits parallel to the inner surface of the hole machined at the tip side of the cutting edge 4, so that reaming can be performed without generating burrs. As a result, a hole can be machined in the workpiece with good quality. It is preferable that the clearance angle of the cutting edge 4 at the maximum diameter position is less than 15° from the viewpoint of preventing chipping and wear of the cutting edge 4.

The rake angle of the cutting edge 4, i.e., the angle between the rake face 11 of the cutting edge 4 and the plane perpendicular to the rotation direction of the cutting edge 4, which is the cutting direction of the workpiece, can be determined according to the material of the workpiece. When the rake angle of the cutting edge 4 is set to 0°, i.e., the rake face of the cutting edge 4 is perpendicular to the cutting surface of the workpiece, it is possible to obtain the effect of making it difficult for delamination to occur when drilling holes in FRP. This is because if the cutting edge 4 does not have a rake angle, the FRP is cut finely, reducing the fraying of the fibers contained in the FRP. Therefore, when emphasis is placed on improving the quality of the holes machined in the FRP, the rake angle of the cutting edge 4 can be set to zero.

Conversely, providing a rake angle to the cutting edge 4 can optimize the drilling conditions when drilling metal. Therefore, when emphasis is placed on improving the quality of the hole to be machined in the metal, a rake angle may be provided to the cutting edge 4. In the example shown in Figure 2, the rake angle of the cutting edge 4 is 0°. In other words, no rake angle is provided to the cutting edge 4.

In this way, by joining the body 2, which has a cutting edge 4 with a specialized shape to improve tool life and drill holes with good quality, to the shank 3, not only is it possible to provide freedom in the shape of the shank 3, such as its length, but it is also possible to drill holes in the workpiece with good quality even if the shank 3 is held in a chuck with different rigidity and insertion length of the shank 3, such as a QA chuck or QB chuck.

The cutting tool shank 3 described above and the cutting tool represented by the drill 1 to which the shank 3 is attached are provided with both a first detachable structure 7A formed on a conventional QA shank and a second detachable structure 7B formed on a conventional QB shank so that they can hold any of a number of chucks with different rigidities and insertion lengths, such as a QA chuck and a QB chuck.

(effect)
Therefore, by using the shank 3, it is possible to easily attach and detach the cutting tool to the hand-held tool rotation device, and it is possible to perform cutting processes such as drilling and reaming with a common cutting tool regardless of whether the part is narrow or not. Specifically, a cutting tool equipped with the shank 3 can be attached to both the QA chuck and the QB chuck. Therefore, it is possible to use a common cutting tool without producing a cutting tool for the QA chuck and a cutting tool for the QB chuck separately.

In addition, by appropriately determining the joining method between the shank 3 and the body 2 and the shape of the cutting edge 4, not only can the drill 1 be held in a QA chuck and a QB chuck, which have different rigidity and insertion length, it is possible to perform good quality hole drilling in the workpiece, but also to avoid a decrease in the tool life of the drill 1.

In fact, a test was conducted in which a drill 1 with a diameter of 0.1935 inches and a shank 3 as shown in Figure 1 was attached to a handheld tool rotation device with a rotation speed of about 2900 rpm, and about 10 holes were drilled in a CFRP piece with a thickness of 12.6 mm and positioned by a drilling plate and a drilling bush. As a result, it was confirmed that holes could be drilled with good accuracy and quality.

Second Embodiment
FIG. 6 is a front view of a drill as an example of a cutting tool having a shank according to the second embodiment.

The drill 1A in the second embodiment shown in FIG. 6 differs from the drill 1 in the first embodiment in the shape of the body 2 including the cutting edge 4. The other configurations and functions of the drill 1A in the second embodiment are not substantially different from those of the drill 1 in the first embodiment, so only a front view of the drill 1A is shown, and the same or corresponding configurations are denoted by the same reference numerals and will not be described.

The cutting edge 4 of the drill 1A in the second embodiment has a first cutting edge 4A, a second cutting edge 4B, and a margin 4C. The first cutting edge 4A is formed on the tip side of the cutting edge 4 and is a cutting edge for drilling a pilot hole in the workpiece. On the other hand, the second cutting edge 4B is formed at a position away from the rear end side of the first cutting edge 4 and is a cutting edge for reaming the pilot hole. Therefore, the second cutting edge 4B is a reamer edge.

The first cutting edge 4A, like the cutting edge 4 in the first embodiment, has a tip angle that is greater than 0° and less than 180° at the tip, which decreases continuously from the tip side to the rear end, while the clearance angle also decreases continuously from the tip side to the rear end. Therefore, when drilling either FRP or metal, the mechanism described in the first embodiment can be used to machine pilot holes in the workpiece while minimizing tool wear.

On the other hand, a clearance angle is formed at the maximum diameter position of the second cutting edge 4B, which functions as a reamer blade. Therefore, similar to the mechanism described in the first embodiment, the second cutting edge 4B at the maximum diameter position hits parallel to the inner surface of the pilot hole machined by the first cutting edge 4A, making it possible to perform reaming without generating burrs. As a result, whether drilling FRP or metal, holes can be machined in the workpiece with good quality.

In addition, a margin 4C is formed between the first cutting edge 4A and the second cutting edge 4B, which reduces the runout of the second cutting edge 4B by being inserted into the pilot hole machined by the first cutting edge 4A. This makes it possible to prevent the runout of the second cutting edge 4B when the second cutting edge 4B is used to ream the hole.

Furthermore, a margin 20 that is continuous with the second cutting edge 4B can be provided on the rear end side of the second cutting edge 4B. In this way, the margin 4C in front of the second cutting edge 4B and the margin 20 behind the second cutting edge 4B can suppress vibration of the second cutting edge 4B from both sides of the second cutting edge 4B.

As a result, whether the shank 3 of the drill 1A is attached to a QA chuck or a QB chuck, which have different rigidities and insertion lengths, the vibration width of the second cutting edge 4B during reaming of the hole can be dramatically reduced. Therefore, even if the length of the shank 3 is shortened, for example as shown in FIG. 4, it is possible to machine the hole with good quality while reducing the risk of breakage of the first cutting edge 4A and the second cutting edge 4B.

In the drill 1A in the second embodiment described above, by forming a margin 4C, 20 on at least one of the cutting edge 4 and the rear of the cutting edge 4 of the drill 1A, the swing width of the cutting edge 4 of the drill 1A is prevented from increasing regardless of whether the shank 3 of the drill 1A is attached to a QA chuck or a QB chuck, which have different rigidities and insertion lengths. Therefore, according to the second embodiment, it is possible to further avoid the adverse effect of an increase in the swing width of the cutting edge 4 caused by attaching a shank 3 having a common shape to both a QA chuck and a QB chuck. As a result, the risk of breakage of the drill 1A can be further reduced and the drilling quality can be further improved.

Third Embodiment
Figure 7 is a projection view showing a first shape example of the cutting edge of a drill as an example of a cutting tool having a shank related to the third embodiment; Figure 8 is a projection view showing a second shape example of the cutting edge of a drill as an example of a cutting tool having a shank related to the third embodiment; Figure 9 is a projection view showing a third shape example of the cutting edge of a drill as an example of a cutting tool having a shank related to the third embodiment; and Figure 10 is a projection view showing a fourth shape example of the cutting edge of a drill as an example of a cutting tool having a shank related to the third embodiment.

The drill 1B in the third embodiment shown in Figures 7 to 10 differs from the drill 1 in the first embodiment in the shape of the cutting edge 4. The other configurations and functions of the drill 1B in the third embodiment are not substantially different from those of the drill 1 in the first embodiment, so only a projection view of the cutting edge 4 is shown, and the same or corresponding configurations are given the same reference numerals and will not be described.

Figures 7 to 10 show the shape obtained by rotating the cutting edge 4 of drill 1B and projecting it onto a projection plane parallel to the tool axis AX. As illustrated in Figures 7 to 10, instead of continuously decreasing the point angle and clearance angle of the cutting edge 4 from the tip side to the rear end side of drill 1B, they may be intermittently decreased. In that case, drill 1B becomes a polygonal drill with multiple point angles.

As a specific example, as illustrated in FIG. 7, on a projection plane parallel to the tool axis AX, a single parabola that is line-symmetric about the projection line of the tool axis AX is set as the reference line RL, and the shape of the cutting edge 4 can be determined so that a broken line that is line-symmetric about the projection line of the tool axis AX and that connects six or more line segments whose both ends are positioned on a single parabola becomes the projection line of the ridge of the cutting edge 4. In this case, the cutting edge 4 becomes a multi-stage cutting edge with three or more stages and at least three or more tip angles α1, α2, and α3. The reference line RL may be replaced from a parabola to an ellipse.

Alternatively, as illustrated in FIG. 8, on a projection plane parallel to the tool axis AX, a single parabola that is line-symmetric about the projection line of the tool axis AX is set as the reference line RL, and the shape of the cutting edge 4 can be determined so that a broken line that is line-symmetric about the projection line of the tool axis AX and that connects eight or more line segments that are tangent to the single parabola becomes the projection line of the ridge of the cutting edge 4. In this case, the cutting edge 4 becomes a multi-stage cutting edge with at least four or more tip angles α1, α2, α3, and α4, with four or more stages. The reference line RL may be replaced from a parabola to an ellipse.

As another example, as illustrated in FIG. 9, on a projection plane parallel to the tool axis AX, two ellipses that are symmetrical about the projection line of the tool axis AX are used as the reference line RL, and the shape of the cutting edge 4 can be determined so that a broken line that is symmetrical about the projection line of the tool axis AX and that connects six or more line segments whose both ends are on the two ellipses closer to the projection line of the tool axis AX is the projection line of the ridge of the cutting edge 4. In this case, the cutting edge 4 is a multi-stage cutting edge with at least three or more tip angles α1, α2, and α3, and in the example shown in FIG. 9, four tip angles α1, α2, α3, and α4 are formed. The reference line RL may be replaced by two parabolas instead of two ellipses.

As yet another example, as illustrated in FIG. 10, on a projection plane parallel to the tool axis AX, some of the multiple line segments constituting the broken line that is the projection line of the ridge of the cutting edge 4 may be line segments that are tangent to a reference line RL such as a parabola or ellipse, and the other part may be line segments with both ends on the reference line RL. In the example shown in FIG. 10, the projection line of the ridge that forms the maximum tip angle α1 of the cutting edge 4 is two line symmetrical line segments that are tangent to the reference line RL consisting of a single parabola or ellipse that is line symmetrical about the projection line of the tool axis AX, and the projection lines of the other tip angles α2, α3, and α4 are line symmetrical line segments with both ends on the reference line RL.

In addition, some of the lines constituting the projection line of the ridge of the cutting edge 4 on a projection plane parallel to the tool axis AX may be replaced with curves such as circular arcs. For example, by connecting the lines with circular arcs, the shape of the cutting edge 4 can be made smooth without corners. In this case, the risk of chipping of the cutting edge 4 can be reduced and the tool life can be extended.

An example of the cutting edge 4 of the drill 1 illustrated in the first embodiment corresponds to a cutting edge 4 in which all line segments except for the line segment constituting the projection line of the ridge that forms the maximum point angle at the tip are replaced with curves such as circular arcs. In particular, from the viewpoint of facilitating design and manufacturing, it is practical to determine the shape of the ridge of the cutting edge 4 so that only the projection line of the ridge of the cutting edge 4 that forms the maximum point angle at the tip is a line segment, and the projection lines of the other ridge portions are curves that smoothly connect arcs with different radii.

According to the third embodiment described above, the shape of each ridge of the cutting edge 4 can be simplified, and manufacturing labor and costs can be reduced. Of course, the shape of the first cutting edge 4A constituting the cutting edge 4 of the drill 1A in the second embodiment may be simplified as illustrated in Figures 7 to 10.

Other Embodiments
Although specific embodiments have been described above, the described embodiments are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein may be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications may be made in the forms of the methods and apparatus described herein without departing from the spirit of the invention. The appended claims and their equivalents include such various forms and modifications as falling within the scope and spirit of the invention.

For example, in each of the above-described embodiments, the drills 1 and 1A are straight-edged drills, but they may be twist drills. In addition, in each of the above-described embodiments, the cutting tool is a drill 1 or 1A having a special shape, but not only when the cutting tool is a drill having a simple shape or another special shape, but also when the cutting tool is a rotary cutting tool such as a simple reamer, end mill, or side cutter, the rotary cutting tool can be configured with a body and shank 3 having a cutting edge such as a reamer blade at the tip.

1, 1A, 1B Drill 2 Body 3 Shank 4 Cutting edge 4A First cutting edge 4B Second cutting edge 4C Margin 5 Joint portion 5A Blind hole 6 Retaining portion 7A First detachable structure 7B Second detachable structure 8A First annular recess 8B Second annular recess 9A First blind hole 9B Second blind hole 10 Flank surface 11 Rake face 20 Margin AX Tool axis D1 First distance D2 Second distance P1 First position P2 Second position RL Reference line L Shank length L1 Joint portion length L2 Retaining portion length LD Blind hole depth α1, α2, α3, α4 Point angle

Claims (5)

A cylindrical or columnar cutting tool shank for holding a cutting tool body in a chuck of a tool rotation device,
a joint having a blind hole having a depth of 5 mm or more for inserting and brazing an end of the body;
a holding portion that is integrated with the joint portion and is for holding the joint portion by the chuck;
having
The holding portion is
a first attachment/detachment structure formed at a first position 10.9 mm away from the end face of the shank on the chuck side in a longitudinal direction of the shank, for attachment to and detachment from a first chuck;
a second attachment/detachment structure formed at a second position 3.3 mm away from the end face on the chuck side in the longitudinal direction of the shank, for attachment to and detachment from a second chuck having a shorter shank insertion length than the first chuck;
and the first mounting/removing structure is configured to be mounted on and removed from the first chuck having a structure for holding a shank with three first spheres movably arranged at the three vertices of an equilateral triangle.
a first annular recess formed so as to be deepest at the first position and have a length direction aligned with a circumferential direction of the shank;
a first three blind holes, each having a depth direction in the radial direction of the shank and having central axes equally spaced apart at an angle of 120° on a first plane perpendicular to the longitudinal direction of the shank at the first position;
On the other hand,
The second mounting/removal structure is configured so that it can be mounted on and removed from the second chuck having a structure for holding a shank with three second spheres movably arranged at the positions of three vertices of an equilateral triangle,
a second annular recess formed so as to be deepest at the second position and have a length direction aligned with a circumferential direction of the shank;
a second three blind holes, each having a depth direction in the radial direction of the shank and having central axes equally spaced apart at an angle of 120° on a second plane perpendicular to the longitudinal direction of the shank at the second position;
and a total length of the shank, which is the sum of the length of the joint portion and the length of the holding portion, is 19 mm or more and 28 mm or less. The shank for a cutting tool according to claim 1, wherein the positions of the second three blind holes are positions obtained by translating the positions of the first three blind holes in the direction of the central axis of the shank. The shank according to claim 1 or 2,
A body having a cutting edge at its front end and the shank brazed to its rear end;
having
A cutting tool in which the brazing is performed in an area of 5 mm or more in the longitudinal direction of the shank. The cutting edge is
A first cutting edge formed on the tip side for drilling a pilot hole in a workpiece;
a second cutting edge formed at a position away from the first cutting edge toward the rear end side for reaming the pilot hole;
A first margin is formed between the first cutting edge and the second cutting edge, and is inserted into the pilot hole machined by the first cutting edge to reduce runout of the second cutting edge;
having
4. The cutting tool according to claim 3, further comprising a second margin continuous with said second cutting edge on said rear end side of said second cutting edge. A cutting method for producing a finished product or semi-finished product by cutting a workpiece with the cutting tool according to claim 3 or 4 .

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