JP2017074650A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill that is able to obtain satisfactory flatness and surface roughness when thinly processing a work piece made of a flexible material such as an aluminum alloy.SOLUTION: In an end mill, the concave of a bottom edge 4 is composed of a primary cutting edge 41 on the corner side of an outer peripheral cutting edge 3 and a secondary cutting edge 42 continuously formed from the primary cutting edge, and at least one cutting edge is provided, which has a gash rand such that the concave angle α of the primary cutting edge has 0° to 30°. The torsion angle γ of the outer peripheral cutting edge is set so as to fall in a range of 30° to 60°, and the concave angle θ of the concave face 5 of the bottom edge is set so as to fall in a range of 30°to 45°, which is smaller than the torsion angle γ.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an end mill, and more particularly to an end mill suitable for bottom finishing of a thin aluminum alloy.

As electronic devices become smaller, lighter, and higher in density, aluminum alloy parts that make up electronic devices are increasingly required to have good flatness and surface roughness. End mills are used to process these parts. used.
As an end mill suitable for processing an aluminum alloy, there is one in which a rake angle (axial rake) of a bottom blade is set to 0 ° to 8 ° (see, for example, Patent Document 1).
Also, as an end mill suitable for bottom finishing of aluminum alloy, the bottom edge is composed of a primary edge and a secondary edge formed continuously from the primary edge and the primary edge on the outer peripheral edge corner. The watermark angle α is 3 ′ to 30 ′, the watermark angle of the secondary cutting edge is 1 ° to 5 °, and the relationship between the watermark angle α of the primary cutting edge and the watermark angle β of the secondary cutting edge is α <Β and the amount of the primary cutting edge is 0.6% to 6.5% of the outer diameter, and the coating film has a thickness of 0.002 to 0.05 mm at least on the primary cutting edge of the end mill tip. (For example, refer to Patent Document 2).

JP 2004-90148 A JP 2000-42822 A

When a thin part is processed by an end mill, residual stress is generated on the processed surface, and when a fixture or the like is removed at the time of processing, deformation occurs due to stress balance, and flatness deteriorates. Residual stress generated during processing is greatly affected by the shape of the tool used for processing and the processing conditions. Also, the surface roughness is greatly influenced by the shape of the tool and the processing conditions.
Although the conventional end mill as described above can improve the surface roughness of the machined surface in any case, it is difficult to achieve both the required flatness and surface roughness even if the machining conditions are adjusted. There was a problem in that reworking and polishing work would occur in the subsequent process.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an end mill capable of obtaining good flatness and surface roughness regardless of processing conditions.

  The end mill according to the present invention comprises a primary cutting edge formed by a primary cutting edge of a corner side of a peripheral cutting edge and a secondary cutting edge formed continuously from the primary cutting edge. An end mill having at least one cutting edge having a gash land in which α is 0 ′ to 30 ′, wherein the torsion angle γ of the outer peripheral cutting edge is 30 ° to 60 °, and the rake angle of the rake face of the bottom edge The angle θ is smaller than the twist angle γ and is in the range of 30 ° to 45 °.

  According to the end mill according to the present invention, since the watermark angle α of the primary cutting edge of the bottom blade is reduced to 0 ′ to 30 ′, good surface roughness can be obtained even if the processing conditions are changed. In addition, since the rake angle θ of the bottom blade is increased to 30 ° to 45 °, the residual stress generated on the processed surface can be reduced, so that the effect of suppressing deformation of the workpiece after processing can be obtained.

The side view which shows the end mill by Embodiment 1 of this invention. The bottom view of the end mill shown by FIG. The principal part enlarged view of the bottom blade of the end mill shown by FIG. The figure explaining the relationship between the surface angle R of the primary cutting edge and the feed amount fz of the primary cutting edge and the surface roughness R when the bottom surface of the workpiece is machined by the end mill. The figure which shows the relationship between the watermark angle (alpha) of the primary cutting edge of the bottom blade measured about the end mill shown in FIG. 1, and the surface roughness of a processed surface. The figure explaining the definition of the deformation amount of the workpiece | work in the bottom face process by an end mill. The characteristic view which shows the result measured about the deformation | transformation amount of the workpiece | work when changing the one-blade feed amount with the end mill by Embodiment 1 of this invention, and a general end mill. The characteristic view measured about the relationship between the rake angle (theta) of a bottom blade and the deformation | transformation amount of a workpiece | work at the time of fixing 1 blade feed amount to 0.2 mm. The figure which shows the pin-cad-shaped cutting blade comprised by at least 1 piece among the several cutting blade in the end mill by Embodiment 2 of this invention. The figure explaining the uncut material of the corner part produced by the shape of a blade edge | tip. The figure explaining the relationship between the surface roughness of a processed surface after the bottom face processing of the workpiece | work by the end mill of Embodiment 2 of this invention, and a watermark angle. The figure explaining the pitch angle of the bottom blade of the end mill by Embodiment 3 of this invention. The side view which shows the structure of the end mill by Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a side view showing an end mill according to Embodiment 1 of the present invention, FIG. 2 is a bottom view of the end mill shown in FIG. 1, and FIG. 3 is an enlarged view of a main part of a bottom blade of the end mill shown in FIG. is there. Throughout the drawings, the same or corresponding members / parts are denoted by the same reference numerals. In the figure, an end mill 1 of the present invention includes an outer peripheral cutting edge 3 formed on an outer peripheral portion of a cylindrical body 2 using a hard material such as an ultrafine particle cemented carbide and a bottom formed on a distal end portion 2 a of the body 2. The bottom edge 4 has a so-called gash land shape in which the rake face 5 of the bottom edge 4 reaches the position of the outer peripheral cutting edge 3, and the watermark of the bottom edge 4 is on the corner side of the outer peripheral cutting edge 3. Primary cutting edge 41 and a secondary cutting edge 42 formed continuously from the primary cutting edge 41.

  And while setting the rake angle γ of the outer peripheral cutting edge 3 to 30 ° to 60 ° and the rake angle θ of the rake face 5 of the bottom blade to a range smaller than the torsion angle γ from 30 ° to 45 °, the primary cutting edge The watermark angle α of 41 is 0 ′ to 30 ′, the watermark angle β of the secondary cutting edge 42 is 1 ° to 6 °, and the width B of the primary cutting edge 41 is 2% to the diameter D of the outer peripheral cutting edge. 4%. A typical characteristic part of the end mill of the present invention is that the cutting angle α of the primary cutting edge 41 is set to 0 ′ to suppress the deformation amount of the workpiece while ensuring good surface roughness with a tool with a gash land. This is because the rake angle θ of the rake face 5 of the bottom blade is set to be as large as 30 ° to 45 ° while being set as small as 30 ′.

  Normally, when a product is machined from a bulk material such as an aluminum alloy, rough processing with a large removal volume is performed in the first step, and finally the dimensional accuracy, shape accuracy and surface roughness specified in the drawing are satisfied. Therefore, the end mill of the present invention can be preferably used for finishing in such a processing technique, and is often performed in two steps of finishing with a reduced removal volume. In particular, even when the thickness of the finished product is thin, for example, 1 to 2 mm, deformation of the workpiece due to residual stress is suppressed, and dimensional accuracy, shape accuracy, and surface roughness can be satisfied. It is what I did. More specific description will be given below.

  The end mill 1 is used by being attached to a spindle of a machine tool such as a machining center through holders such as shrink fitting type and collet type which are not shown. At the time of machining, a main shaft such as a machining center rotates, whereby rotation is transmitted to the end mill 1 through holders, and the direction indicated by an arrow T around the axis O as shown in FIG. The workpiece is cut by the outer peripheral cutting edge 3 and the bottom edge 4 to form a machining surface by being sent in a direction intersecting the axis O while rotating clockwise when viewed downward (in the direction of the cutting edge). To do. At this time, the length that the tool advances for each cutting edge of the tool is referred to as a single blade feed amount. The single-blade feed amount is an index related to the removal volume, and is one of the processing conditions that have a great influence on the residual stress and surface roughness generated during processing. This one-blade feed amount is obtained by the following equation (1).

Single blade feed amount fz [mm / blade] =
Tool feed rate [mm / min] / tool rotation speed [1 / min] / tool blade count [blade] ... Equation (1)
Hereinafter, the single-blade feed amount fz shown in Expression (1) will be described as an index indicating the feed amount of the tool.
FIG. 4 is a diagram for explaining the relationship between the cutting edge angle α of the primary cutting edge and the single-blade feed amount fz and the surface roughness R of the machined surface when the bottom surface of the workpiece is machined by the end mill. Since the surface roughness R of the bottom surface is a transfer of the shape of the bottom edge of the end mill, when the single blade feed amount fz is smaller than the width B of the primary cutting edge, the single blade feed amount and the corner angle of the primary cutting edge 41 It is represented by the following formula (2) using α.
Surface roughness R [μm] = single blade feed amount × tan (α) × 1000 (2)
From the equation (2), it can be seen that the surface roughness R becomes worse as the one-blade feed amount fz is increased or the watermark angle α is increased.

  In a general end mill, the bottom edge is one continuous cutting edge, and the watermark angle α is set to 2 ° to 6 °. In order to improve the surface roughness R, if the watermark angle α is simply reduced, the contact area of the bottom cutting edge will increase, so the resistance during cutting will increase and the surface roughness will deteriorate due to chattering etc. There is. On the other hand, in Embodiment 1 of the present invention, the secondary cutting edge 42 formed continuously from the primary cutting edge 41 is provided at the bottom edge of the bottom cutting edge, and the cutting angle α of the primary cutting edge 41 is set to 0. The surface roughness R is improved by reducing it to ˜30 ′, while the corner angle β of the secondary cutting edge 42 is set to 1 ° to 6 °, which is larger than the corner angle α of the primary cutting edge 41. Thus, the contact area is reduced and the increase in cutting resistance is suppressed, so that a good surface roughness can be obtained without chattering or the like during cutting.

  FIG. 5 shows an end mill in which the torsion angle γ of the outer peripheral cutting edge shown in FIG. 1 is 30 ° to 60 ° and the rake angle θ of the rake face of the bottom blade is in the range of 30 ° to 45 ° smaller than the torsion angle γ. It is a figure which shows the relationship between the watermark angle | corner (alpha) of the primary cutting edge of the bottom blade measured about surface roughness R of the processed surface. Here, as shown by the white circles in FIG. 5, a tool with the primary cutting edge α changed to 30 ′ (= 0.5 °), 2 °, 4 °, and 6 ° is manufactured. The relationship between the surface angle and the cutting angle α of the primary cutting edge measured when an aluminum alloy workpiece is machined with a single blade feed amount fz of 0.1 mm is shown. In any case, the blade edge diameter D = 20 mm, the outer peripheral cutting edge twist angle γ = 45 °, the bottom cutting edge rake angle θ = 30 °, the primary cutting edge width B = 0.6 mm (outer periphery). 3% of the cutting edge diameter D), and the secondary cutting edge angle β is β = 2 ° when α <2 °, β = α when α ≧ 2 °, and the material is ultrafine particles. A cemented carbide was used.

  From FIG. 5, it can be seen that the result of the test almost coincides with the formula (1), and that the surface roughness deteriorates as the watermark angle α increases. More specifically, the upper limit value of the one-blade feed amount fz is, for example, about 0.4 mm, and the allowable value of the surface roughness R is about 3.2 μm or less, so that the range can be sufficiently satisfied. In order to obtain the surface roughness R, it was confirmed by a test conducted separately from FIG. 5 that the primary cutting edge angle α should be 0 to 30 ′.

  Next, the amount of deformation of the workpiece after machining can be suppressed by setting the rake angle θ of the bottom blade to a range of 30 ° to 45 ° which is larger than the usual 0 ° to 8 °. FIG. 7 for explanation. 6 is a diagram for explaining the definition of the deformation amount of the workpiece in the bottom machining by the end mill, and FIG. 7 is a diagram when machining by changing the one-blade feed amount between the end mill according to Embodiment 1 of the present invention and a general end mill. It is a characteristic view which shows the result measured about the deformation amount w of the workpiece | work. Here, a block-shaped aluminum alloy A5052 having a workpiece deformation amount w (μm) of 30 mm × 10 mm is prepared, and the end mill fixed to the main spindle of the machining center so that its thickness is 1.5 mm is shown in FIG. As indicated by the bold bold arrows, the amount of warpage when the workpiece was released after being sent in the longitudinal direction of the aluminum alloy was defined as the deformation amount w and evaluated. Positive deformation was defined as convex warpage, and negative deformation was defined as concave warpage. Further, the diameter D (shown in FIG. 1) of the end mill blade edge was 20 mm, and the rotation speed was 4775 rotations / minute.

  In FIG. 7, a black triangle mark is a general tool with a rake angle θ = 6 °, and a white circle mark is a tool according to an embodiment of the present invention with a rake angle θ = 30 °. This is a result of evaluating the amount of deformation w of the workpiece after machining by cutting the above-described block-shaped aluminum alloy A5052 while changing the feed into three stages of 0.1, 0.2, and 0.3. As for the other items of the tool, the twist angle γ = 45 °, the primary cutting edge angle α = 24 ′ (= 0.4 °), the secondary cutting edge angle β = 2 °, The cutting edge width B was 0.6 mm, and the material was an ultrafine particle cemented carbide. Note that the tool with a bottom edge rake angle θ = 6 ° indicated by a black triangle mark is said to reduce the strength of the blade edge when the bottom edge rake angle θ exceeds 8 ° in an end mill with a gash land. In general, since θ = 0 ° to 8 ° is set in order to ensure the strength of the blade edge, it is created as a representative example of the range for comparison.

  As is clear from FIG. 7, it was confirmed that by increasing the rake angle θ of the bottom blade to 30 °, deformation can be suppressed as compared with a rake angle θ as small as 6 °. Since the deformation tends to change from convex to concave by increasing the single blade feed amount, the rake angle θ is set to 0 ° to 8 ° by increasing the single blade feed amount fz beyond the evaluated range. Although it can be considered that the deformation amount w can be reduced even with a general tool of about °°, the single-blade feed amount is generally in the range of about 0.5 to 1.5% of the diameter D of the tool. If the condition is such that the feed amount per blade exceeds 2%, it may not be possible for the tool to be lost or the machine tool to be unable to follow.

  FIG. 8 is a characteristic diagram measured for the relationship between the rake angle θ of the bottom blade 4 and the amount of deformation of the workpiece when the single blade feed amount is fixed to 0.2 mm. The other parameters of the end mill in this case are the same as in FIG. From FIG. 8, it can be seen that the rake angle θ is set in the range of 30 ° to 45 °, whereby the deformation amount of the workpiece after machining can be suppressed to about ± 5 μm or less with a length of 30 mm. When the rake angle θ is larger than 36 °, the deformation tends to change into a concave shape. When the rake angle θ is larger than 45 °, the deformation becomes large in the concave shape and the flatness deteriorates. By using 30 ° to 45 °, it is possible to obtain a good surface roughness when used for finishing light metals such as aluminum alloys, and the residual stress generated on the processed surface is reduced, so that deformation of the workpiece can be achieved. It was also confirmed that processing can be preferably performed without causing problems such as chipping due to a decrease in the strength of the blade edge. The reason why the twist angle γ of the outer peripheral cutting edge is set to 30 ° to 60 ° is that in order to provide a gash land, the twist angle γ> the rake angle θ needs to be satisfied. As a result of intensive research on the rake angle θ as described above, the rake angle θ, which has a significant difference in effect, is in the range of 30 ° to 45 °.

  As described above, the end mill according to the first embodiment is provided with a gash land, and the bottom of the bottom blade 4 is formed continuously from the primary cutting edge 41 on the corner side of the outer peripheral cutting edge and the primary cutting edge. In an end mill comprising a cutting edge 42 and a primary cutting edge 41 with a sharpening angle α of 0 ′ to 30 ′ and a small cutting edge, the twist angle γ of the outer peripheral cutting edge 3 is 30 ° to 60 °, and the bottom blade The rake angle θ of the rake face of 4 is in the range of 30 ° to 45 ° at an angle smaller than the helix angle γ, and larger than the end mill having a general rake angle θ of 0 ° to 8 °. Is. According to the first embodiment configured as described above, the corner angle α of the primary cutting edge 41 is set to 0 ′ to 30 ′, and the rake angle θ of the bottom edge 4 is set to an angle smaller than the twist angle γ. By setting it in the range of 30 ° to 45 °, a remarkable surface roughness can be obtained at the same time that a good surface roughness can be obtained in the finishing process of the aluminum alloy, and at the same time, the flatness of the workpiece can be improved. An effect is obtained. For this reason, both the good flatness and surface roughness required when processing thin metal workpieces such as aluminum alloys with an end mill as the electronic equipment becomes smaller, lighter, and denser. A satisfactory product can be produced. Further, it is possible to eliminate the occurrence of subsequent processes such as reworking and polishing work.

Embodiment 2. FIG.
FIG. 9 is a view showing a pin-cad-shaped cutting edge constituted by at least one of a plurality of cutting edges in the end mill according to Embodiment 2 of the present invention, (a) is an enlarged view of a main part, and (b). It is a figure which shows the rake angle (theta) 2 and the torsion angle (gamma) 2 of an outer peripheral cutting edge. FIG. 10 is a diagram for explaining the uncut portion of the corner caused by the shape of the cutting edge, and FIG. 11 is a graph showing the relationship between the surface roughness of the processed surface after machining the bottom surface of the workpiece by the end mill according to Embodiment 2 of the present invention and the corner angle. It is a figure explaining. In the second embodiment, when the number of cutting edges of the end mill is plural, at least one of the cutting edges of the bottom blade 4 is the same as that shown in FIG. 3 in the first embodiment. In the shape with a so-called gash land reaching the outer peripheral cutting edge 3, the cutting angle α of the primary cutting edge 41 is set to 0 ′ to 30 ′, and the rake angle θ of the bottom cutting edge 4 is set to 30 ° to 45 °. The bottom edge 4A of at least one of the other cutting edges is a so-called pin-caded shape in which the rake face 5A does not reach the outer peripheral cutting edge 3 as shown in FIG. 9 (a). is there. In the case of a pin quad shape, as shown in FIG. 9B, the torsion angle γ2 of the outer peripheral cutting edge 3 is the same as the rake angle θ2 of the bottom edge 4A. It should be noted that the twist angle γ2 of the above-mentioned pincad cutting edge may be the same as the rake angle θ of the bottom edge 4 constituting the cutting edge with a gash land.

As is well known to those skilled in the art, the rake face 5 of the tool with a gash land is produced by removing a part of the outer peripheral cutting edge 3, so that the cutting edge is retracted at the tip portion, and when used for machining the corner portion, In the vicinity of the tip (corner), an uncut portion is generated as shown in FIG. The smaller the difference between the rake angle θ of the bottom blade and the twist angle γ of the outer peripheral cutting edge 3 from the geometrical shape, the smaller the uncut portion becomes. In a pin-cad tool, the twist angle γ2 of the outer peripheral cutting edge 3 is the rake angle of the bottom blade. Since it is the same as θ2, there is no uncut portion near the tip as shown in FIG. Further, since the pin CAD tool is formed in a shape in which the bottom edge 4A is hollowed out in the vicinity of the outer peripheral edge 3, the substantial watermark angle α2 is increased. Therefore, it can be seen from the formula (1) that the surface roughness is deteriorated.
The cutting edge is composed of a bottom blade extending radially outward from the center of rotation of the end face of the end mill, and an outer peripheral cutting edge formed from the bottom blade to the outer peripheral surface of the end mill. It is counted by the number of its bottom blades or the number of outer peripheral cutting blades.

The end mill of the second embodiment has a configuration in which a cutting edge with a gash land and a cutting edge with a pin quad shape are provided in one tool as described above, so that even if uncut material is generated by the blade with a gash land, Since the uncut portion can be sharply processed by the pin caddy blade, the entire tool can be processed without causing uncut portions in the corners. In this embodiment, since at least one bottom blade 4 with a gashland having a watermark angle α of 0 ′ to 30 ′ is provided, the surface roughness of the processed surface is a watermark angle α as shown in FIG. The surface roughness is determined by a complex surface formed by a substantial watermark angle α2, and the surface roughness is excellent.
As described above, according to the second embodiment, it is possible to obtain a good surface roughness and a good flatness, and an effect that the cutting can be efficiently performed with one tool without generating an uncut residue in the corner portion. Is obtained. Further, since a gash land and a pin caddy blade are provided in one tool, the time required for tool change and the probability of chipping can be suppressed.

Embodiment 3 FIG.
FIG. 12 is a view for explaining the pitch angle of the bottom blade of the end mill according to Embodiment 3 of the present invention. In the third embodiment, when the number of cutting edges of the end mill is plural, at least one of them is the rake face 5 of the bottom blade 4 in the same manner as that shown in FIGS. 1 to 3 in the first embodiment. With a so-called gashland shape that reaches the outer peripheral cutting edge 3, with the primary cutting edge 41 having a corner angle α of 0 ′ to 30 ′ and a bottom edge rake angle θ of 30 ° to 45 °. 9 and at least one of the other blades, as shown in FIG. 9, has a rake face 5A that does not reach the outer peripheral cutting edge 3, and has a so-called pincad shape, and a helix angle γ is the bottom blade of the blade with the above-mentioned gash land In the case where the rake angle θ is equal to 4, the cutting edge is formed so that the pitch angle φ of the bottom edge is constant as shown in FIG. In the example shown in the figure, the number of cutting edges is 2 and the pitch angle φ of the bottom edge is 180 °, but the number of cutting edges may be 3 or more. You can choose either the attached shape or the pin-caded shape for the larger number.

  According to the third embodiment configured as described above, when machining the bottom surface of the workpiece, it becomes an equal pitch end mill, so that the thickness that is geometrically shaved by each cutting edge is constant, and stable machining is achieved. It can be performed. Further, when machining the side surface of the workpiece, the above-described configuration causes a difference in torsion angle, so that the pitch angle of the outer peripheral cutting edge 3 varies depending on the height in the axial direction. It becomes an end mill. Since the end mill with unequal pitch and unequal lead has the effect of suppressing vibration during processing, in addition to the effect of the second embodiment described above, the end mill can perform stable processing without chatter during processing. A further effect of being able to do so is obtained.

Embodiment 4 FIG.
FIG. 13 is a side view showing the configuration of an end mill according to Embodiment 4 of the present invention. In the figure, the end mill 1A of the fourth embodiment has the same cutting edge as that of the first embodiment shown in FIGS. 1 to 3, that is, the outer peripheral cutting edge 3 and the bottom cutting edge 4, and the rake face of the bottom cutting edge 4 5 has a shape with a so-called gash land that reaches the outer peripheral cutting edge 3, and the watermark of the bottom blade 4 is continuous from the primary cutting edge 41 on the corner side of the outer peripheral cutting edge 3 and the primary cutting edge 41. The secondary cutting edge 42 is formed. The torsion angle γ of the outer peripheral cutting edge 3 is 30 ° to 60 °, and the rake angle θ of the rake face 5 of the bottom blade is smaller than the torsion angle γ and is in the range of 30 ° to 45 °. The primary cutting edge 41 has a watermark angle α of 0 ′ to 30 ′, the secondary cutting edge 42 has a watermark angle β of 1 ° to 6 °, and the width of the primary cutting edge 41 is equal to the diameter of the outer peripheral cutting edge. An end mill having a cutting edge of 2% to 4% is configured by dividing the cutting blade portion 21 and the shank portion 22, and the cutting blade portion 21 is detachably screwed to the shank portion 22. Here, the rear end side of the cutting edge portion 21 is a male screw portion 21a, and a female screw portion 22a that is coaxially screwed to the male screw portion 21a is provided at the tip of the shank portion 22 formed of a shaft. The material of the portion 22 is made of a material such as high speed steel which is cheaper and easier to process than cemented carbide.

  In the fourth embodiment configured as described above, the shank portion 22 is used by being attached to a spindle of a machine tool such as a machining center via a holder or the like, and the cutting blade portion 21 is formed by the male screw portion 21a and the female screw portion 22a. The rotation is transmitted to and processing is performed. When configured in this way, it becomes possible to replace only the cutting edge portion 21 related to cutting, so that the amount of hard material such as expensive ultrafine particle cemented carbide can be suppressed, and a tool can be manufactured at low cost. The effect that it can do is acquired. Needless to say, the configuration of the cutting edge portion 21 may be the same as that of the second or third embodiment.

Embodiment 5. FIG.
The fifth embodiment has the same cutting edge as that of the first embodiment shown in FIGS. 1 to 3, that is, the outer peripheral cutting edge 3 and the bottom cutting edge 4, and the rake face 5 of the bottom cutting edge 4 is the outer peripheral cutting edge 3. The bottom edge 4 has a shape with a so-called gash land, and the secondary edge is formed by the primary edge 41 on the corner side of the outer peripheral edge 3 and the primary edge 41 continuously. The blade 42 is constituted. The twist angle γ of the outer peripheral cutting edge 3 is set to 30 ° to 60 °, and the rake angle θ of the rake face 5 of the bottom blade is set to a range of 30 ° to 45 ° which is smaller than the twist angle γ. The primary cutting edge 41 has a watermark angle α of 0 ′ to 30 ′, the secondary cutting edge 42 has a watermark angle β of 1 ° to 6 °, and the width B of the primary cutting edge 41 is the diameter of the outer peripheral cutting edge. In the end mill having 2% to 4% of D, the surface of the cutting edge portion is coated with a hard film such as DLC (diamond-like carbon) (not shown). In addition, the structure shown in Embodiment 2 to 4 may be sufficient as the part of a cutting blade.
In the fifth embodiment, by configuring as described above, the affinity with the aluminum alloy that is the work material can be lowered, and effects such as prevention of welding to the cutting edge portion and improvement of wear resistance can be achieved. Can be obtained.

Embodiment 6 FIG.
The fifth embodiment has the same cutting edge as that of the first embodiment shown in FIGS. 1 to 3, that is, the outer peripheral cutting edge 3 and the bottom cutting edge 4, and the rake face 5 of the bottom cutting edge 4 is the outer peripheral cutting edge 3. The bottom edge 4 has a shape with a so-called gash land, and the secondary edge is formed by the primary edge 41 on the corner side of the outer peripheral edge 3 and the primary edge 41 continuously. The blade 42 is constituted. The torsion angle γ of the outer peripheral cutting edge 3 is set to 30 ° to 60 °, and the rake angle θ of the rake face 5 of the bottom blade is set to an angle smaller than the torsion angle in the range of 30 ° to 45 °. The primary cutting edge 41 has a watermark angle α of 0 ′ to 30 ′, the secondary cutting edge 42 has a watermark angle β of 1 ° to 6 °, and the width B of the primary cutting edge 41 is the diameter of the outer peripheral cutting edge. In the end mill having 2% to 4% of D, the number of cutting edges is only one.
By adopting a configuration in which the number of cutting edges is only one, the manufacturing error for each cutting edge when the number of cutting edges is plural is eliminated, and the manufacture of the tool is facilitated.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  1, 1A end mill, 2 body, 2a tip, 21 cutting edge, 21a male thread, 22 shank, 22a female thread, 3 outer cutting edge, 4 bottom cutting edge, 4A bottom cutting edge (pin caddy shape), 41 primary Cutting edge, 42 Secondary cutting edge, 5 Rake face, 5A Rake face (pin caddy shape), B Primary cutting edge width, D Outer peripheral cutting edge diameter, O axis, R Surface roughness, fz Single cutting edge feed amount, w Deformation amount, α Primary cutting edge angle, α2 Substantial cutting edge angle (pin cadence shape), β Secondary cutting edge angle, γ helix angle, γ2 helix angle (pin cadence shape), θ Bottom edge rake angle, θ2 Bottom edge rake angle (pin caddy shape).

Claims (7)

  The watermark of the bottom edge is composed of a primary cutting edge on the corner side of the outer peripheral cutting edge and a secondary cutting edge formed continuously from the primary cutting edge, and the watermark angle α of the primary cutting edge is set to 0 ′ to 30 ′. An end mill having at least one cutting edge having a gash land as described above, wherein a twist angle γ of the outer peripheral cutting edge is 30 ° to 60 °, and a rake angle θ of a rake face of the bottom blade is determined from the twist angle γ. An end mill characterized by having a small angle in a range of 30 ° to 45 °.   The secondary cutting edge has a watermark angle β of 1 ° to 6 °, and the width B of the primary cutting edge is 2% to 4% of the diameter D of the outer peripheral cutting edge. Item 1. The end mill according to Item 1.   The edge cutting edge γ2 of the peripheral cutting edge is the same as the rake angle θ2 of the rake face of the bottom cutting edge, and is provided with at least one cutting edge having a pinch shape together with at least one cutting edge having a gash land. The end mill according to claim 1 or 2.   The end mill according to claim 3, wherein a pitch angle φ of the bottom edge of the plurality of cutting edges is constant.   The end mill according to claim 1 or 2, wherein the number of cutting edges is one.   The end mill according to any one of claims 1 to 5, wherein the portion provided with the cutting edge is detachably coupled to the shank portion.   The end mill according to any one of claims 1 to 6, wherein a hard coating is applied to a surface of the cutting edge.

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