JP2011020248A - Router end mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a router end mill capable of prettily cutting resin and fiber, that are components of a material to be cut, while suppressing vibration, and capable of suppressing generation of cutting chips and largely suppressing generation of burrs, during cutting a plate-like FRP material. <P>SOLUTION: As a router end mill having a twisted main cutting blade composed of at least four cutting edges, it is preferable to use a router end mill having at least five nick-shaped cutting edges arranged at a reverse helix angle to a helix angle of the main cutting edge. Where, the number of threads of grooves of the nick-shaped cutting edges is different from that of grooves of the main cutting edges. Further, it is preferable that, in the numerical relationship between the number of grooves of the main cutting edges and that of threads of grooves of the nick-shaped cutting edges, a difference obtained by subtracting the number of threads of grooves of the nick-shaped cutting edges from the number of grooves of the main cutting edges is within a range of not less than -2 and not more than 2 excluding 0. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a router end mill used for cutting a plate made of a fiber reinforced plastic (FRP) material.

In recent years, FRP materials have been widely used as structural materials for vehicles, automobiles, and aircraft because of the feature that the weight of structures can be reduced and the tensile strength can be greatly improved. As the fiber material contained in the material, glass fiber, aramid fiber, carbon fiber, and the like are mainly used, and uses of various fibers have been extended to various structural materials in place of conventional metal materials.
Conventionally, as a tool for cutting these FRP materials, a cemented carbide tool called a diamond router end mill, which is a deburring tool, in which a left helix blade groove and a right helix blade groove intersect is generally used. .

  Further, although there is no mention of cutting of FRP material, as a cutting tool having a shape similar to a diamond router end mill, for example, a router end mill with a nick that mainly cuts a thin plate material such as a printed circuit board (Patent Document 1) And chip breakers having the same action as Nick (see Patent Document 2).

In addition, as a cutting tool used for cutting an aluminum honeycomb core material, there are tools having symmetrical twist angles (Patent Document 3 and Patent Document 4).
The router end mill described in Patent Document 3 is characterized in that the nick twist arrangement and the blade groove twist are the same right direction when viewed from the handle side, and the difference in twist angle is 30 ° or more. The chip discharge direction is described as being guided in the handle direction. The router end mill described in Patent Document 4 includes a first cutting edge having a twist angle of 30 ° to 60 ° and a positive rake angle, and a second cutting edge having a twist angle and a positive rake angle symmetrical to the first cutting edge. Therefore, in side cutting of thick aluminum honeycomb core material with thick walls, it is possible to prevent burn-in of the cutting edge and welding of chips, and further, if the tool life is prolonged by crushing the chips finely Are listed.

No. 7-51205 JP 2002-337016 A JP 2008-114308 A JP 2002-18629 A

  The fibers contained in the FRP material include fibers whose tensile strength has been improved to the same level as or higher than that of steel materials. Therefore, the conventional cutting shows extremely difficult cutting properties, and the uncut fibers are burrs on the cutting surface. Or the laminated fiber layers are peeled off, and the high strength of the original FRP material is impaired. Further, these fibers have a strong action of abrading the cutting edge of the tool, and in particular, a CFRP material containing carbon fibers has a problem that the tool life is extremely shortened.

  Conventional conventional diamond carbide router end mills have the same twist angle on the left and right twist grooves, and the left and right twist blade grooves have substantially the same groove depth, so they interfere with each other. The length of the cutting edge located on the outer cylindrical surface is very small, and the cutting edge is almost like a quadrangular pyramid-shaped projection. Especially in the cutting of FRP material containing fibers, the function of cutting fibers is greatly improved. Resulting in a very short tool life. Also, conventional diamond router end mills are originally intended for deburring, so the left and right twisted blade groove depths are often set too shallow, and the fibers that could not be cut by cutting remain long. There is a problem that the tool life is shortened due to clogging.

  The router end mill described in Patent Document 1 is a router end mill that mainly cuts a thin plate material such as a printed circuit board. Nick is notched in a direction substantially orthogonal to the axial direction of the tool body, and the flank angle in the cross-sectional view of Nick The ratio of the length of the flank to the depth of the nick is set, and its purpose is to improve the cutting edge strength, and the accompanying action is a reduction in cutting resistance and heat generated during machining. It is only possible to suppress this.

  The router end mill described in Patent Document 2 is characterized in that the nick width is larger than the cutting edge length divided by the nick, which improves chip discharge and increases the supply of coolant by the cutting fluid. Although it is described that the cooling effect of the cutting edge is improved, the burr suppressing effect at the time of cutting the FRP material is unclear. In addition, the nicks here are described as being arranged so as to be substantially orthogonal to the twisting blade and having a rectangular cross section.

  Patent Document 3 and Patent Document 4 do not mention the burr suppressing effect when cutting the FRP material.

  As described above, conventionally known router end mills have a problem that tool life is shortened due to chip clogging in cutting of FRP material, a problem that burrs are generated, and a problem that peeling occurs between layers. It was. For this reason, realization of a router end mill suitable for cutting of FRP material is desired.

In order to meet the above demand, the router end mill of the present invention is arranged at a reverse twist angle with respect to the twist angle of the main cutting edge in the router end mill having a twisted main cutting edge composed of at least four blades. At least 5 or more nick-shaped cutting edges are provided, and the number of grooves of the nick-shaped cutting edge is different from the number of blade grooves of the main cutting edge.
By configuring in this way, the positions of the nick grooves from the tool tips of the main cutting edges are not synchronized, and are arranged in a constant twisted arrangement, and if the tool rotates once, a substantially vertical cutting surface can be obtained. Has an effect.

  Furthermore, in the present invention, the nick-shaped cutting edge is different from a so-called nick, and has a structure in which the ridge line on the shank side is the cutting edge among the crossing ridge lines between the nick groove and the land of the main cutting edge. By providing the nick-shaped cutting edge having such a structure, the FRP without generating burrs on the upper and lower surfaces of the plate-like FRP material due to the action of the twisted main cutting edge and the twisted nick-shaped cutting edge. The material can be cut.

  In the present invention having the above configuration, the twist angle of the array of nick-shaped cutting edges is arranged at a larger twist angle than the main cutting edge, and the length X of the main cutting edge divided by this nick-shaped cutting edge is It is preferable to distribute more than the width Y of the shape cutting edge.

  In the present invention, the rake angle of the nick-shaped cutting edge is preferably a regular angle. As a result, cutting performance is improved, and burrs on the upper surface of the FRP material can be reduced.

Furthermore, in the present invention, the twist angle of the main cutting edge is preferably 10 ° to 30 °, the rake angle is 6 ° to 20 °, and the blade groove depth is preferably 10% to 20% of the blade diameter. . By configuring in this way, when cutting plate-like FRP material, the resin and fibers that are the components of the work material can be cut cleanly while reducing vibrations, and chip clogging is suppressed, greatly generating burrs. Can be suppressed.
In the router end mill of the present invention, the main cutting edge and the nick-shaped cutting edge are preferably made of cemented carbide. By using a cemented carbide, a long-life tool with high wear resistance can be realized. In the router end mill of the present invention, it is desirable to coat the main cutting edge and the nick-shaped cutting edge with a hard coating having a hardness of 50 GPa or more. By configuring in this way, it is possible to significantly improve the time during which the sharpness of the cutting edge that suppresses the generation of burrs can be maintained, and it is possible to realize a router end mill made of a super hard material having a longer life.

  According to the present invention, in the cutting of the FRP material that exhibits difficult cutting properties because the tensile strength contains fibers or the like improved to the steel material level or higher, uncut fibers remain as burrs on the cutting surface, Cutting can be performed without peeling the laminated fiber layers, and the high strength characteristics of the original FRP material are not impaired.

It is a side view which shows an example of embodiment of this invention. It is a front view of FIG. The cross section perpendicular to the axis of the main cutting edge of the present invention is shown. It is an enlarged view around a nick groove. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. It is an enlarged view when the main cutting edge and the nick groove are viewed from the direction perpendicular to the tool axis. It is a figure showing the positional relationship of the FRP board of a workpiece, and the router end mill of this invention. It shows the relationship between the work material position when the number of groove grooves of the main cutting edge is the same as the number of grooves of the nick-shaped cutting edge and the state where the tool is unfolded once. The state which unfolded 1 rotation of the work material and the tool of the example of the present invention is shown. It is the figure which showed the expansion | deployment state at the time of 1 rotation of a tool, and a workpiece material when the difference which pulled the groove | channel number of the nick-shaped cutting edge from the number of groove grooves of the main cutting edge is larger than two. It is the figure which showed the expansion | deployment state at the time of one rotation of a tool, and a cut material in case the difference of the number of groove grooves of a main cutting edge and the number of groove | channels of a nick-shaped cutting edge is smaller than -2. It shows the state where the work material and the tool of another example of the present invention are developed by one rotation. It is a side view of the other Example of this invention. It is a front view of the other Example of this invention shown in FIG. It is the figure which showed the state at the time of FRP material cutting by the tool of the example of this invention. It is the figure which showed the state at the time of FRP material cutting by the tool of a comparative example.

As described above, the router end mill of the present invention has a twisted main cutting edge and is provided with a nick-shaped cutting edge arranged at a reverse helix angle with respect to the helix angle of the main cutting edge. The number of grooves on the cutting edge is different from the number of grooves on the main cutting edge.
1 and 2 are diagrams illustrating a schematic configuration of a router end mill showing an example of an embodiment of the present invention. 1 is a side view, and FIG. 2 is a front view of FIG.
As shown in FIG. 2, the router end mill of the present invention is provided with a main cutting edge 2 having a twist angle θ1 of the main cutting edge with respect to the tool rotating shaft 5 on the front end side of the router end mill 1, and the rear end side is It becomes the shank part 3. Further, a nick groove 6 is provided in the land 8, and a nick-shaped cutting edge 7 provided at a twist angle θ2 of the nick-shaped cutting edge is formed on a ridge line formed by the nick groove 6 and the land 8. The number of grooves of the nick-shaped cutting edge 7 is different from the number of grooves of the main cutting edge 2 so that the nick grooves 6 do not exist at the same position in a cross-sectional view orthogonal to the tool rotation axis 5. It is formed. Thus, since the number of grooves of the nick-shaped cutting edge 7 is different from the number of groove grooves of the main cutting edge 2, the nick positions from the tool tips of the main cutting edge 2 are not synchronized and are arranged in a constant twist arrangement. If the tool rotates once, a substantially vertical cutting surface can be obtained. Although FIG. 1 shows an example of an embodiment of the present invention in which the tool front end surface 4 has no bottom blade, the present invention can also be applied to an end mill having a bottom blade.

As shown in FIG. 2, the twist angle θ2 of the nick-shaped cutting edges 7 arranged in a left-handed twist is in a relation of θ2> θ1 with respect to the twist angle θ1 of the main cutting edge 2 formed by a right-hand twist. The length X of the main cutting edge 2 set and divided by the nick-shaped cutting edge 7 is preferably arranged so as to be larger than the nick width Y of the nick-shaped cutting edge 7.
When the nick width Y is too larger than the length X of the main cutting edge 2, a non-cutting portion is generated and the surface accuracy of the processed surface is lowered. That is, if the length X of the main cutting edge 2 is smaller than the nick width Y, the uncut portion due to the nick increases even after one rotation, resulting in a decrease in surface roughness, and an increase in the need to refinish the process. .
On the other hand, if the nick width Y becomes too smaller than the length X of the main cutting edge 2, chips generated by the nick-shaped cutting edge 7 are likely to be clogged, resulting in a problem that the life is shortened.
Therefore, for example, when the blade diameter is in the range of φ4 to φ16 mm, the length X of the main cutting edge 2 is preferably 1 mm or more and 5 mm or less, and the nick width Y is 0.5 mm or more and 2.5 mm or less. It is preferable that the ratio of X and Y is 0.5 ≦ Y / X <1.

In general, since the tool is used in a clockwise rotation, in the above description, the main cutting edge is described as a right-handed twist, and the nick-shaped cutting edge is described as a left-handed twist arrangement. It is also possible to use a left-handed twist and a nick-shaped cutting edge in a right-handed twist arrangement. However, in this case, since the chips are pressed by the bottom blade, the cutting ability of the cuts is inferior, so that it is not suitable for pocket processing.
In rare cases, the tool may be rotated counterclockwise. In such a case, the main cutting edges are left-handed and the nick-shaped cutting edges are right-handed, or the main cutting edges are used. Even when the right-handed twist is used and the nick-shaped cutting edges are arranged in a left-handed twist, the same action and effect as when the tool is rotated in the right direction are obtained.

FIG. 3 shows one main cutting edge in a cross section perpendicular to the axis. The rake angle of the main cutting edge is indicated by α and the depth of the groove is indicated by F. In the router end mill of the present invention, the twist angle of the main cutting edge is 10 ° to 30 °, the rake angle α of the main cutting edge is 6 ° to 20 °, and the groove depth F is 10% to 20% of the blade diameter D. It is preferable that
If the twist angle of the main cutting edge is less than 10 °, the intermittent cutting performance increases, the vibration of the plate material increases, and the occurrence of burrs increases. On the other hand, when the twist angle of the main cutting edge exceeds 30 °, for example, when the main cutting edge is right-handed, the action of lifting the plate material increases, so that the vibration increases and the generation of burrs increases. On the other hand, when the main cutting edge is left-handed, the action of pressing down the plate material is increased, resulting in large vibrations, making it difficult to prevent burrs. For this reason, the twist angle of the main cutting edge is appropriately 10 ° to 30 °.

  The rake angle α of the main cutting edge is suitably 6 ° to 20 °. FRP basically requires a large rake angle suitable for resin cutting because resin is a representative component. When the rake angle α of the main cutting edge exceeds 20 °, when the force for gripping the plate-shaped work material is low, the work material itself vibrates due to cutting vibration, which may cause chipping of the cutting edge. On the other hand, if the rake angle α of the main cutting edge is less than 6 °, the fibers contained in the FRP cannot be cut cleanly and may remain as burrs, which is inappropriate.

  The blade groove depth F is suitably 10% to 20% of the blade diameter. When the blade groove depth F exceeds 20%, the rigidity of the entire tool decreases, and the tool strength is weak for a work material such as CFRP that falls into a very hard category among the types of FRP. Tool vibration increases and burr generation increases. On the other hand, when the groove depth F is less than 10%, there is a risk that chips are clogged in pocket machining or the like. Furthermore, the depth of the nick-shaped cutting edge is inevitably reduced, and chips are clogged at the nick portion, leading to generation of burrs.

Furthermore, in the present invention, the nick-shaped cutting edge preferably has a positive rake angle. FIG. 4 is an enlarged view around the nick groove. In the present invention, in addition to the main cutting edge 2, a nick groove 6 is provided on the land 8, and a nick-shaped cutting edge 7 is formed on a ridge formed by the nick groove 6 and the land 8. FIG. 5 is a cross-sectional view taken along line AA in FIG. The hatched portion in FIG. 5 shows a cross section. The nick-shaped cutting edge 7 has the rake angle β of the positive nick-shaped cutting edge, and the nick portion 6 is formed in a substantially U shape.
In the present invention, the rake angle β of the nick-shaped cutting edge is preferably a positive angle of 0 ° to 10 °. If the rake angle β of the nicked cutting edge is negative, the sharpness of the nicked cutting edge will be reduced, burrs will be generated in a short time, cutting resistance will increase, and if the work material is thin FRP material, cutting vibration Becomes larger, causing the problem of delamination in the resin. On the other hand, when the rake angle β of the nick-shaped cutting edge exceeds 10 °, the strength of the intersection of the nick-shaped cutting edge and the main cutting edge becomes weak, causing a problem that chipping occurs and the tool life is shortened.

FIG. 6 is an enlarged view of the main cutting edge and the nick groove when viewed from the direction perpendicular to the tool axis. The main cutting edge 2 is connected to a nick groove 6. When the main cutting edge 2 is viewed from the direction perpendicular to the tool axis, the length X is the length of the main cutting edge, and the nick groove 6 is set to the tool axis. The length when viewed from the vertical direction is represented by a nick width Y. In the present invention, the length X of the main cutting edge is preferably arranged to be larger than the nick width Y of the nick-shaped cutting edge.
When the nick width Y is too larger than the length X of the main cutting edge, a non-cutting portion is generated and the surface accuracy of the processed surface is lowered. In other words, if the length X of the main cutting edge is smaller than the nick width Y, the uncut portion due to the nick increases even after one rotation, resulting in a decrease in surface roughness, which increases the need for refinishing.
On the other hand, if the nick width Y is too smaller than the length X of the main cutting edge, chips generated by the nick-shaped cutting edge 7 are likely to be clogged, resulting in a problem that the life is shortened.
Therefore, for example, when the blade diameter is in the range of φ4 to φ16 mm, the length X of the main cutting edge is preferably in the range of 1 mm to 5 mm, and the nick width Y is in the range of 0.5 mm to 2.5 mm. The ratio of X and Y is preferably 0.5 ≦ Y / X <1.

FIG. 7 is a diagram showing the positional relationship between the FRP plate of the work material and the router-end mill of the present invention. One twisted main cutting edge contacts the lower surface of the FRP plate to perform a cutting action. This represents a state in which the upper surface of is cut with a nick-shaped cutting edge that is twisted opposite to the main cutting edge. The difference between the oblique lines of the work material 10 indicates the laminated fiber layers that are characteristic of the FRP plate. Further, the extension line 11 on the upper surface of the work material and the extension line 12 on the back surface of the work material are shown in order to clarify the contact location of the main cutting edge and the nick-shaped cutting edge.
When the work piece 10 is cut using the router-end mill of the present invention, the place where cutting is performed differs between the main cutting edge 2 and the nick-shaped cutting edge 7. The cutting area where the cutting is performed at that time is the cutting area 14 by the nick-shaped cutting edge which is the area cut by the nick-shaped cutting edge 7 and the main cutting edge which is the area cut by the main cutting edge 2. The cutting area 13 is classified. In the present invention, since the number of grooves of the nick-shaped cutting edge is different from the number of groove grooves of the main cutting edge, the cutting area 13 by the main cutting edge and the cutting area 14 by the nick-shaped cutting edge are not synchronized, and the tool rotates once. In this way, an advantageous effect that cannot be obtained by the conventional technique, that is, a substantially vertical cutting direction can be obtained.

In the router-end mill of the present invention, the numerical relationship between the number of grooves on the main cutting edge and the number of grooves on the nicked cutting edge is the difference obtained by subtracting the number of grooves on the nicked cutting edge from the number of grooves on the main cutting edge. Is preferably in the range of −2 or more and 2 or less (excluding 0).
Hereinafter, the case where the number of groove grooves of the main cutting edge, the number of grooves of the nick-shaped cutting edge, the length of the main cutting edge, and the nick width are changed will be described with reference to FIGS.
FIG. 8 shows the relationship between the work material position and the state in which the tool is unfolded once when the number of groove grooves of the main cutting edge and the number of grooves of the nick-shaped cutting edge are the same. The specification of the tool shown in FIG. 8 is that the number of grooves of the main cutting edge 2 is 6 (that is, the number of blades is 6), and the number of grooves of the nick-shaped cutting edge 6 is also 6 (that is, the number of grooves of the nick groove 6 is 6). ). A1 to A6 represent the number of grooves on the main cutting edge, and a1 to a6 represent the number of grooves on the nick-shaped cutting edge. The difference between the oblique lines of the work material 10 indicates that the FRP plate as the work material has a laminated structure. Further, the extension line 11 on the upper surface of the work material and the extension line 12 on the back surface of the work material are shown in order to clarify the contact location of the main cutting edge and the nick-shaped cutting edge.
In this case, since the number of groove grooves of the main cutting edge 2 and the number of grooves of the nick-shaped cutting edge 6 are the same, the positions of the nick grooves 6 are synchronized. Therefore, the cutting area 13 by the main cutting edge and the cutting area 14 by the nick-shaped cutting edge are always constant. As a result, the uncut portion 15 is generated in the work material 10.

FIG. 9 shows the relationship between the work material position when the number of blade grooves and the number of grooves are different and the state where the tool of the example of the present invention is unfolded once. The specification of the tool of the example of the present invention shown in FIG. 8 is that the number of main cutting edge blade grooves is 6, and the number of grooves of the nick-shaped cutting edge is 5. A1 to A6 represent the number of grooves on the main cutting edge, and a1 to a5 represent the number of grooves on the nick-shaped cutting edge. The difference between the oblique lines of the work material 10 indicates that the FRP plate as the work material has a laminated structure. Further, the extension line 11 on the upper surface of the work material and the extension line 12 on the back surface of the work material are shown in order to clarify the contact location of the main cutting edge and the nick-shaped cutting edge.
At this time, since the number of groove grooves of the main cutting edge and the number of grooves of the nick-shaped cutting edge are different and the position of the nick groove 6 is not synchronized, the nick-shaped cutting edge 7 having a twisting blade action opposite to that of the main cutting edge 2 is obtained. It always acts on the upper surface of the work material during one rotation, and the occurrence of burrs on the upper surface of the work material can be suppressed.
As described above, according to the present invention formed so that the number of blade grooves and the number of grooves are different, there is an effect of suppressing the generation of burrs on the front surface and the back surface when processing the plate material of the FRP material.

FIG. 10 is a view showing a developed state and a work material at the time of one rotation of the tool when the difference obtained by subtracting the number of grooves of the nick-shaped cutting edge from the number of grooves of the main cutting edge is larger than 2. The specification of the tool shown in FIG. 10 is that the number of groove grooves of the main cutting edge is 6, and the number of grooves of the nick-shaped cutting edge is 3. That is, the difference obtained by subtracting the number of grooves of the nick-shaped cutting edge from the number of cutting grooves of the main cutting edge is 3. A1 to A6 represent the number of grooves on the main cutting edge, and a1 to a3 represent the number of grooves on the nick-shaped cutting edge. The difference between the oblique lines of the work material 10 indicates that the FRP plate as the work material has a laminated structure. Further, the extension line 11 on the upper surface of the work material and the extension line 12 on the back surface of the work material are shown to clarify the contact location of the main cutting edge 2 and the nick-shaped cutting edge 7.
When cutting was performed using the router end mill of the present invention, in order to remove burrs generated on the upper surface and the back surface of the work material 10, they were arranged at a reverse twist angle with respect to the twist angle of the main cutting edge. It is necessary to remove burrs with the nick-shaped cutting edge, but when using a tool in which the difference obtained by subtracting the number of grooves on the nick-shaped cutting edge from the number of grooves on the main cutting edge is greater than 2, Since the number of grooves on the nick-shaped cutting edge is small, the effect of suppressing the upper surface burr due to the reverse twisting blade action on the nick-shaped cutting edge 7 may not be exhibited depending on the position of the work material 10. Also in FIG. 10, since the difference obtained by subtracting the number of grooves of the nicked cutting edge from the number of grooves of the main cutting edge is larger than 2, the upper surface and the back surface of the workpiece 10 cannot be cut by the nicked cutting edge 7. Thus, burrs generated on the upper surface and the back surface of the work material 10 cannot be removed. In order to solve this, it is necessary to match the upper surface of the work material and the height of the nick-shaped cutting edge 7, which increases the difficulty of the setup work for performing the cutting process.

FIG. 11 is a view showing a developed state and a work material when the tool is rotated once when the difference obtained by subtracting the number of grooves of the nick-shaped cutting edge from the number of grooves of the main cutting edge is smaller than −2. The specification of the tool shown in FIG. 11 is that the twist angle of the main cutting edge is 19 ° to the right, the number of groove grooves of the main cutting edge is 6 grooves, the twist angle of the nick-shaped cutting edge is 45 ° to the left, and the groove of the nick-shaped cutting edge The number of articles is 9. That is, the difference obtained by subtracting the number of grooves of the nick-shaped cutting edge from the number of cutting grooves of the main cutting edge is 3. A1 to A6 represent the number of grooves on the main cutting edge, and a1 to a9 represent the number of grooves on the nick-shaped cutting edge. The difference between the oblique lines of the work material 10 indicates that the FRP plate as the work material has a laminated structure. Further, the extension line 11 on the upper surface of the work material and the extension line 12 on the back surface of the work material are shown in order to clarify the contact location of the main cutting edge and the nick-shaped cutting edge.
At this time, the length X of the main cutting edge becomes smaller than the nick width Y of the nick-shaped cutting edge, the action of the main cutting edge 2 is reduced, and the action of suppressing the generation of burrs is reduced.

  FIG. 12 shows a state in which the work material and the tool of another example of the present invention are developed by one rotation in the same manner as FIG. The specifications of the example of the present invention shown in FIG. 12 are arranged such that the twist angle of the main cutting edge is 19 ° to the right, the number of blade grooves is 6 blades, the twist angle of the nick-shaped cutting blade is 45 ° to the left, and the number of grooves is 9 threads. For example, the difference obtained by subtracting the number of grooves of the nick-shaped cutting edge from the number of cutting grooves of the main cutting edge is -3. A1 to A6 represent the number of grooves on the main cutting edge, and a1 to a9 represent the number of grooves on the nick-shaped cutting edge. The difference between the oblique lines of the work material 10 indicates that the FRP plate as the work material has a laminated structure. Further, the extension line 11 on the upper surface of the work material and the extension line 12 on the lower surface of the work material are shown in order to clarify the contact location of the main cutting edge and the nick-shaped cutting edge. In this case, the nick groove 6 is provided in order to ensure the length X of the main cutting edge to be larger than the nick width Y of the nick-shaped cutting edge. However, the nick width Y must be reduced, and chip dischargeability is improved. As a result, the chips are easily clogged and the burr suppression effect is reduced.

  From the above, in the present invention, the numerical relationship between the number of grooves on the main cutting edge and the number of grooves on the nicked cutting edge is the difference obtained by subtracting the number of grooves on the nicked cutting edge from the number of grooves on the main cutting edge. Is preferably in the range of −2 or more and 2 or less (excluding 0).

FIG. 1 shows an example in which six main cutting edges are provided. However, the present invention is not limited to this example. For example, as shown in FIGS. Various forms such as a shape having 12 grooves and six bottom blades can be adopted. For example, when the main cutting edge 2 of the router end mill 1 is right-twisted, a clean bottom surface can be obtained because all of the main cutting edge 2 is involved even during step cutting or pocket machining using the bottom edge 16 for machining. It is done.
In the present invention, when the number of groove grooves of the main cutting edge is as small as less than 4, the cutting interruptability increases, and when trimming and cutting a thin plate material such as FRP, the vibration of the plate material increases and burrs are generated. Fear arises. For this reason, in the present invention, the number of blade grooves of the main cutting edge is preferably 4 or more, and more preferably 6 or more. Although depending on the blade diameter, the number of groove grooves of the main cutting edge is preferably 16 or less in practice.

Further, in the present invention, the twisted main cutting edge and the nicked cutting edge are made of cemented carbide, so that they have excellent characteristics such as wear resistance, and a preferable router end mill can be obtained. In particular, it is most desirable to use a diamond sintered body for the main cutting edge and the nick-shaped cutting edge and to produce the above-mentioned cutting edge specifications. A preferable tool can also be obtained when a cemented carbide alloy or the like is used as a tool base material and the surface of the main cutting edge and the nick-shaped cutting edge is subjected to a hard diamond coating coating treatment. Further, a DLC coated film that has a hardness lower than that of diamond coated but with a sharp edge is preferable because of its great effect of suppressing burrs.
EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited by the following Example.

In each example shown in the following table, the present invention example, the conventional example, and the comparative example are shown as classifications, and the sample numbers are indicated by consecutive serial numbers for each of the present invention, the conventional example, and the comparative example.
Example 1
As Example 1 of the present invention, a main cutting edge having a blade diameter D of 12 mm, a right helix angle of 20 °, a blade groove depth of 1.8 mm (15% of the blade diameter), and a rake angle of 10 ° (ie, a main cutting edge). The router of the present invention is also provided with 6) blade grooves and a 45 ° twisted arrangement on the left, the rake angle β of the nick-shaped cutting edges is 5 °, and the number of grooves of the nick-shaped cutting edges is 8 grooves. An end mill was produced. The length X of the main cutting edge was 3.4 mm, and the nick width Y was 2.2 mm.
As Comparative Example 1, there is no nick-shaped cutting edge, and other specifications are the router end mill having the same specifications as Example 1 of the present invention, that is, the blade diameter D is 12 mm, the right helix angle is 20 °, and the blade groove depth is 1. A 6-blade router end mill with only a right twist main cutting edge of 8 mm and a rake angle of 10 ° was produced.
The router end mill of Invention Example 1 and the router end mill having no nick-like cutting edge of Comparative Example 1 were used, and the work material was FRP containing aramid fibers having a processing length of 0.25 m and a plate thickness of 6 mm. Cutting conditions were a cutting speed of 226 m / min, a feed speed of 1200 mm / min, and trimming was performed with a cutting depth of 0.5 mm in the radial direction of the tool. As an evaluation method, vibration noise during cutting was measured, and the surface state of the workpiece was visually observed every machining length of 0.25 m to confirm the presence or absence of burrs. Burr was not generated at the processing length of 1 m, and vibration noise during cutting was 95 dB or less. The results are shown in Table 1.

  FIG. 15 is a view showing a state when the FRP material is cut by the tool of the present invention. FIG. 16 is a diagram showing a state when cutting the FRP material with the comparative example tool. The example of the present invention did not generate burrs on the front and back surfaces even after a cutting length of 3 m, and the vibration sound was a good result of 75 db. On the other hand, the router end mill without the nick-shaped cutting edge of Comparative Example 1 stopped cutting because burrs were generated on the surface after cutting 0.5 m. Further, the vibration sound at that time was 98 db. As a result, the router end mill according to the present invention suppresses the vibration of the FRP plate by the nick-shaped cutting edge of the left-twisted arrangement opposite to the main cutting edge of the right-twisted arrangement, while the burr on the back surface is generated by the right-twisted main cutting edge. It can be seen that burrs on the surface can be prevented with the nick-shaped cutting blades in the left array.

(Example 2)
In Invention Examples 2 to 7, the blade diameter D is 10 mm, the number of blades is 12, the twist angle of the main cutting edge is 15 ° to the right, the number of blade grooves of the main cutting edge is 12, and the twist angle of the nick-shaped cutting edge is Router end mills each having 45 ° on the left and the number of grooves on the nick-shaped cutting edge being 9, 10, 11, 13, 14, and 15 were produced one by one. The groove depth of the main cutting edge is 1.5 mm (15% of the blade diameter), the rake angle is 10 °, the rake angle of the nick-shaped cutting edge is 3 °, and the length X of the main cutting edge is nicked. The ratio Y / X with the blade width Y was 0.8.
As Comparative Example 2, the twist angle of the nick-shaped cutting edge is 45 ° to the left, the number of grooves is 12, and the other specifications are router end mills having the same specifications as the example of the present invention, that is, the blade diameter D is 10 mm, the main cutting. The blade groove depth is 1.5 mm (15% of the blade diameter), the rake angle is 10 °, the rake angle of the nick-shaped cutting edge is 3 °, the length X of the main cutting edge and the width Y of the nick cutting edge. A router end mill with a ratio Y / X of 0.8 was prepared.
The router end mill of the present invention example and the router end mill of the comparative example were used, and a CFRP material having a plate thickness of 4 mm was used as the work material. Cutting conditions were a cutting speed of 200 m / min, a feed speed of 1200 mm / min, and trimming was performed with a cutting depth of 0.5 mm in the radial direction of the tool. The evaluation method was the same as in Example 1. The results are shown in Table 2.

  In Invention Examples 3 to 6, no burr was generated on the front and back surfaces even after a cutting length of 3 m, and the vibration noise was 95 dB or less. In Invention Examples 2 and 7, fine burrs were observed after 1.5 m cutting, but no burrs were generated when the cutting length was 1 m, and the vibration noise was 95 dB or less. On the other hand, Comparative Example 2 has a nick-shaped cutting edge with the same number of twelve grooves as the number of the main cutting edge. Therefore, a portion without cutting edge due to interference is created, and an uncut portion is generated from the beginning of cutting. Delamination and burrs occurred.

(Example 3)
In Examples 8 to 12, except that the ratio Y / X between the length X of the main cutting edge and the width Y of the nick cutting edge and the number of grooves of the nick cutting edge were changed, the blade diameter D was 10 mm, the blade The number of blades is 12, the twist angle of the main cutting edge is 15 ° to the right, the number of blade grooves of the main cutting edge is 12, and the groove depth of the main cutting edge is 1.5mm (15% of the blade diameter), rake angle Was set at 10 °, the rake angle of the nick-shaped cutting edge was 3 °, and one router end mill with a unified specification was produced. In Invention Examples 8 to 12, the number of grooves of the nick-shaped cutting edge is set to 6, 8, 9, 10, and 15, respectively, and the ratio Y / X between the length X of the main cutting edge and the width Y of the nick cutting edge is set respectively. 0.3, 0.5, 0.8, 0.9, and 1.1 were set.
The work material, cutting conditions, and evaluation method were the same as in Example 1. The results are shown in Table 3.

In Invention Examples 10 to 11, no burr was generated on the front and back surfaces even after a cutting length of 5 m, and the vibration noise was low. In Example 9 of the present invention, generation of minute burrs was observed, but the vibration noise was small and the cutting surface was normal.
On the other hand, in Example 8 of the present invention, the ratio Y / X of the width Y of the nick cutting edge to the length X of the main cutting edge is as small as 0.3 (that is, the pocket of the nick cutting edge is small), and the nick cutting Chips due to the blades are easily clogged, and the effect of suppressing the plate-like work material is reduced, and the gusset surface and vibration noise are increased.
In Example 12 of the present invention, Y / X> 1, that is, the nick width Y is larger than the length X of the main cutting edge, so that a portion that remains to be cut occurs even if the tool rotates once, and the cutting surface becomes rough. In addition, the vibration noise increased.
From these results, it is desirable that the ratio of the length X of the main cutting edge to the width Y of the nick is 0.5 ≦ Y / X <1.

Example 4
Except for changing the rake angle β of the nick-shaped cutting edge as Examples 13 to 17 of the present invention, the blade diameter D is 10 mm, the number of blades is 12, the helix angle of the main cutting edge is 20 ° to the right, the cutting edge of the main cutting edge The number of grooves is 12, the depth of the main cutting edge is 1.5mm (15% of the blade diameter), the rake angle is 8 °, the ratio of the main cutting edge length X and the nick cutting edge width Y Y / X was 0.8, the twist angle of the nick-shaped cutting edge was 45 ° to the left, the number of grooves was 9, and one router end mill with unified specifications was produced. In Examples 13 to 17 of the present invention, the rake angle β of the nick-shaped cutting edge was set to −3 °, 0 °, 6 °, 10 °, and 12 °. A CFRP material having a thickness of 10 mm was used as the work material. Conditions and evaluation methods were the same as in Example 1. The results are shown in Table 4.

Examples 14 to 16 of the present invention have a positive rake angle β in the nick-shaped cutting edge, so that the sharpness of the cutting edge is excellent, and there is an effect of suppressing burrs on the surface of the plate-like workpiece, and vibration noise Is also small.
On the other hand, Example 13 of the present invention in which the rake angle β was negative was inferior in sharpness and produced a loud vibration noise, and the burr generation time was relatively early.
On the contrary, in the case of the present invention example 17 where the rake angle β of the nick-shaped cutting edge is large, the initial sharpness is good, but the edge edge strength at the intersection of the nick-shaped cutting edge and the main cutting edge becomes weak and chipping occurs. The cutting vibration suddenly increased after cutting 1.5 m, and the cutting surface also became rough.
Accordingly, the rake angle β of the nick-shaped cutting edge is preferably in the range of 0 ° to 10 °.

  The router end mill of the present invention is provided with at least 5 or more nick-shaped cutting edges arranged at a reverse helix angle with respect to the helix angle of the twisted main cutting edge having at least 4 blades. The router end mill is characterized in that the number of grooves of the shaped cutting edge is different from the number of grooves of the main cutting edge. By providing such a nick-shaped cutting edge, the action of the twisted main cutting edge and the twisted nick-shaped cutting edge, the FRP material can be formed without generating burrs on the upper and lower surfaces of the plate-like FRP material. Cutting is possible. The application field is suitable for the cutting of FRP materials used for structural materials of vehicles, automobiles or aircraft.

DESCRIPTION OF SYMBOLS 1 Router end mill 2 Main cutting edge 3 Shank part 4 Tool front end surface 5 Tool axis 6 Nick groove 7 Nick-shaped cutting edge 8 Land 9 Intersection point of main cutting edge and nick-shaped cutting edge 10 Work material 11 Extension line of work material upper surface 12 Extension line on the back of the work material 13 Cutting area with the main cutting edge 14 Cutting area with the nick-shaped cutting edge 15 Uncut portion 16 Bottom edge D Blade diameter θ1 Torsion angle of the main cutting edge θ2 Torsion angle of the nick-shaped cutting edge α Main Cutting edge rake angle β Nicking edge rake angle F Blade groove depth X Length of main cutting edge Y Nick width A1 Number of cutting grooves of main cutting edge (1st groove)
A2 Number of grooves on the main cutting edge (second groove)
A3 Number of groove in the main cutting edge (3rd groove)
A4 Number of grooves on the main cutting edge (4th groove)
A5 Number of grooves on the main cutting edge (5th groove)
A6 Number of groove in the main cutting edge (6th groove)
a1 Number of grooves on nick-shaped cutting edge (1st line)
a2 Number of grooves on nick-shaped cutting edge (second line)
a3 Number of grooves on nick-shaped cutting edge (3rd line)
a4 Number of grooves on nick-shaped cutting edge (4th line)
a5 Number of grooves on nick-shaped cutting edge (5th line)
a6 Number of grooves on nick-shaped cutting edge (6th line)
a7 Number of grooves on nick-shaped cutting edge (7th line)
a8 Number of grooves on nick-shaped cutting edge (8th line)
a9 Number of grooves on nick-shaped cutting edge (9th line)

Claims (3)

  In a router end mill having a twisted main cutting edge composed of at least four blades, at least five or more nick-shaped cutting edges arranged at a reverse helix angle with respect to the helix angle of the main cutting edge are provided, A router end mill, wherein the number of grooves on the nick-shaped cutting edge is different from the number of grooves on the main cutting edge.   The router end mill according to claim 1, wherein the rake angle of the nick-shaped cutting edge has a positive rake angle.   The router end mill according to claim 1 or 2, wherein the twist angle of the nick-shaped cutting edge is arranged with a helix angle larger than that of the main cutting edge, and the main cutting edge is divided by the nick-shaped cutting edge. A router end mill characterized in that the length X is larger than the nick width Y of the nick-shaped cutting edge.

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