JPH0144261Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a throw-away milling tool in which a throw-away tip is detachably attached to the outer periphery of the tool body.

[Prior art] In recent years, as cutting tools such as end mills and face milling cutters, throw-away type cutting tools have been developed, in which a plate-shaped throw-away tip (hereinafter referred to as a tip) is detachably attached to the outer periphery of the tip of the tool body. Milling tools (hereinafter abbreviated as milling tools) are frequently used. By the way, among such milling tools, the milling tool in which the above-mentioned chip is attached from the outer peripheral side of the tool body with its upper surface as the outer circumferential relief surface has a lower profile than the conventional milling tool that does not use a chip. Many types of materials have been developed because they offer various advantages such as improving the rigidity of materials and making them easier to process.

FIGS. 16 to 22 show conventional milling tools of this type.

In FIGS. 16 and 17, reference numeral 1 indicates the tool body of this milling tool. The tool body 1 has a cylindrical shape that rotates around an axis X, and a portion of the outer circumference of the tip thereof is cut out at predetermined intervals along the circumferential direction in a substantially semicircular shape when viewed from the bottom. A plurality of chip pockets 2 (one of which is shown in the figure) are formed. A tip mounting seat 3 is formed on the rear end side of the tip pocket 2 of the tool body 1 in the rotational direction. The tip mounting seat 3 has a rectangular recess connected to the tip pocket 2 on one side, with a tip mounting surface 4 on the surface facing the outer circumference of the tool body 1, and a chip mounting surface 4 on the side facing the rotation direction of the tool body 1. A receiving surface 5 is formed respectively. A tip 6 is mounted on the tip mounting seat 3 of the tool body 1.

As shown in FIGS. 20 to 22, this chip 6 has a parallelogram-like appearance with upper and lower surfaces 7 and 8 parallel to each other, and the lower surface 8 is a seating surface on which the chip mounting seat 3 is placed. In addition, the upper surface 7
Main cutting edges 9, 9 are formed at the ridge portion on the long side. Then, in a portion of a predetermined width along the main cutting edge 9 of the upper surface 7, a lower surface 8 is gradually formed from the center side of the upper surface 7 toward the main cutting edge 9 at an angle shown by β in FIG. A chamfer surface 10 is formed which slopes to the side. Also, the side surface 11 from the main cutting edge 9 to the lower surface 8 of the chip 6 is formed to be inclined toward the center of the chip 6 at an angle shown by α in the figure. has been done. Note that the reference numeral 12 in the figure indicates a mounting hole for this chip 6.

This chip 6 is shown in FIGS. 16 and 1.
As shown in FIG. 7, the lower surface 8 serving as a seating surface is brought into contact with the tip mounting surface 4 of the tool body 1, and is removably fixed by a clamp screw 13 inserted into the mounting hole 12. Here, the above tip 6
The main cutting edge 9 is centered on the axis X of the tool body 1, with the chamfer surface 10 serving as the outer circumferential flank surface and the upper surface 7
Positive axial rake angle A and radial rake angle R
It is attached and attached. Incidentally, the radial rake angle R is the line connecting the axis X and the main cutting edge 9,
If the angle formed by the line passing through the axis X and perpendicular to the upper and lower surfaces 7 and 8 of the chip 6 is R ₁ , then the angle is expressed by (R ₁ −α).

[Problems to be solved by the invention] Generally speaking, in such a milling tool, the axial rake angle A and the radial rake angle R of the chip to be mounted are both set large in the positive direction to reduce cutting resistance and cutting heat. It is known that the occurrence of this phenomenon is further reduced, making it possible to perform cutting with even higher efficiency.

However, in the conventional milling tool described above, as shown in FIG. 22, the lower surface 8, main cutting edge 9, and upper surface 7 of the chip 6 installed are parallel to each other, and therefore, as shown in FIG. As shown in FIG. 19, if an attempt is made to increase the axial rake angle A, the length H of the tip 6 in the outer circumferential direction of the tool body 1, which must be positioned within the rotation locus Y described above, becomes long. In other words, in order to position the chamfer surfaces 10, 10 and the upper surface 7 of the chip 6 inside the rotation locus Y, the angle indicated by the above-mentioned _R1 inevitably becomes large, so the above-mentioned R= In order to make the radial rake angle R more positive by α-R ₁ , the inclination angle α of the side surface 11 must also be made larger in advance in proportion to the amount of increase in the angle R ₁ . As a result, the angle of the cutting edge of the tip 6 becomes small, which reduces the strength of the cutting edge and causes chipping or chipping, and further deteriorates seating rigidity, resulting in a reduction in cutting load resistance. It was hot.

In addition, in the conventional milling tool described above, if the axial rake angle A of the chip 6 is set large, the radius of the rotation locus at the center of the main cutting edge 9 will be larger than the tip, as shown in FIG. The radius becomes smaller than the radius of the rotation locus Y at the rear end and the rear end.
For this reason, as shown in FIG. 22, the machined surface of the workpiece is cut into a convex curved shape that swells somewhat outward at a position corresponding to the center of the main cutting edge 9. There was also a problem in that it resulted in a decrease in cutting accuracy.

[Purpose of the invention] This invention was made in view of the above circumstances.
It is possible to increase both the axial rake angle and the radial rake angle without deteriorating the strength of the cutting edge or the seating rigidity, which enables highly efficient cutting, as well as excellent cutting accuracy. The purpose is to provide tools.

[Means for Solving the Problems] The milling tool of this invention has a lower surface serving as a seating surface on the outer periphery of the tool body which is rotated around an axis;
And when the upper surface is viewed from the side along a diagonal line connecting a pair of corner portions of the upper surface, this diagonal line portion is the top, and each corner portion is directed from this diagonal line portion to another corner portion with this diagonal line in between. to draw an arc in which the thickness between the upper and lower surfaces gradually decreases, and the center of one of these arcs is located on the other arc side of an imaginary line drawn from the diagonal line at right angles to the lower surface. , a rectangular plate-shaped chip formed by two convex curved surfaces whose arc center of the other arc is located on the one arc side from the imaginary line, and the other corner part is connected to the tip of the tool body in the rotational direction. The main cutting edge formed on the ridge of the upper surface is positioned on the outer peripheral side of the tool body.

[Example] Figs. 1 to 9 show an example of a milling tool of this invention.

In FIGS. 1 and 2, reference numeral 20 indicates the tool body of this milling tool, and a portion of each is located at four locations equally spaced in the circumferential direction on the outer periphery of this tool body 20. A chip pocket 21 is formed which is cut out in a semicircular shape when viewed from the bottom and drawn in a spiral along the axial direction. A plurality of chip mounting seats 22 are formed along the longitudinal direction on the rear end side of each chip pocket 21 in the rotational direction, and a chip 23 is removably attached to each of these chip mounting seats 22. is installed on.

As shown in FIGS. 3 to 5, this chip 23 is a plate-shaped member with an approximately diamond-shaped appearance, and its lower surface 24 serves as a seating surface, and the ridges of its upper surface 25 are Cutting edges 26, 26 are formed. As shown in FIG. 5, this upper surface 25 has acute corner portions 28 and 28, respectively, from the diagonal line M when viewed from the side along a diagonal line M connecting the obtuse corner portions 27 and 27 of the upper surface 25.
Draw an arc in which the thickness between the upper and lower surfaces ₂₄ and 25 gradually decreases toward It is formed by two cylindrical convex curved surfaces 29, 29 located on the cutting side, and the arc center _C2 of the other arc is located on the one arc side from the imaginary line P. Note that the reference numeral 30 in the figure indicates a mounting hole for this chip 23.

As shown in FIGS. 6 and 7, these chips 23... are arranged so that their respective acute corner portions 28... are located on the leading end side of the tool body 20 in the rotational direction. Similarly, the clamp screws 31 inserted into the respective mounting holes 30 are attached to the tip mounting seats 22 of the tool body 20 with positive axial rake angles A and radial rake angles R, respectively. There is.

Therefore, in the case of such a milling tool, the upper surface 25, which is the outer circumferential relief surface of the chip 23 mounted, is connected to the obtuse corner portions 27, 2 of the upper surface 25.
In a side view from a direction along a diagonal line M connecting 7, an arc is drawn from this diagonal line M toward the acute corner parts 28 and 28, respectively, so that the thickness between the upper and lower surfaces 24 and 25 gradually decreases. Since it is formed by two convex curved surfaces 29, 29, as shown in FIG _. It becomes extremely small. Therefore, as shown in FIGS. 8 and 9, even when the axial rake angle A is increased, the tip 2 passes through the line connecting the axis X and the main cutting edge 26 and the axis X.
The amount of change in R ₂ of the angle formed by the lower surface 24 of No. 3 and a line orthogonal to the line can be kept extremely small. Therefore, there is no need to increase the angle of inclination α of the side surface 32 of the chip 23, and highly efficient cutting can be performed without the blade edge strength deteriorating the seating rigidity.

Moreover, in the case of this milling tool, the tip is 23.
Since the main cutting edge 14 is formed in an arc shape, the eighth
As shown in the figure, by appropriately setting the arc radius of the upper surface 25, the rotation locus over the entire length of the main cutting edge 26 can be made to coincide with the same rotation locus Y. Therefore, the machined surface of the material to be cut can be cut flat, and excellent cutting accuracy can also be obtained.

[Other Examples] Figures 10 to 14 show other examples of the milling tool of this invention, and parts common to those shown in Figures 1 to 9 are designated by the same reference numerals. The explanation will be omitted.

10 and 11, in the milling tool of this example, chips 33 are removably mounted on the chip mounting seats 22 of the tool body 20, respectively. Here, this chip 33 has its main cutting edge 26 as shown in FIGS. 12 to 14.
The inclination angle α ₁ of the side surface 34 from 1 to the lower surface 24 is the first
It is formed to be larger than that shown in FIGS. And, between the lower end 34a of this inclined side surface 34 and the lower surface 24, a diamond-shaped plate-shaped seating portion 36 is formed, the opposing side surfaces 35... being parallel to each other.

However, even in the case of the milling tool in this example, the first
The same effects as those shown in FIGS. 9 to 9 can be obtained.

In the above embodiments, the chips 23 and 32 each have a substantially rhombic shape in appearance, but the present invention is not limited to this.
As long as the chip is formed in the same shape as 3 and 32, the same effect can be obtained even if a chip having a parallelogram, rectangle, square or other rectangular plate shape in appearance is attached. Also, the type of chip installed is not limited to the same type.
For example, as shown in FIG.
2... while installing this tool body 4.
The tip 23 having a substantially diamond-shaped appearance as shown in the above embodiment may be attached to the tip mounting seat 41 at a position where the main cutting edge requires front relief, such as the tip side of the tip.

[Effects of the invention] As explained above, the milling tool of this invention has a lower surface serving as a seating surface, and an upper surface that connects a pair of corner portions of the upper surface to the outer periphery of the tool body that is rotated about the axis. In a side view from a direction along a diagonal line connecting the above, this diagonal line portion is the top, and the thickness between the upper and lower surfaces gradually decreases from this diagonal line portion toward other corner portions sandwiching this diagonal line in between. A circular arc is drawn, and the arc center of one of these arcs is located on the other arc side from an imaginary line drawn from the diagonal line at right angles to the lower surface, and the arc center of the other arc is located on the imaginary line. A rectangular plate-shaped chip formed by two convex curved surfaces located on the one arcuate side is placed so that the other corner part is located on the tip side in the rotational direction of the tool body, and on the ridge part of the upper surface. The formed main cutting edge is positioned and mounted on the outer peripheral side of the tool body. Therefore, according to this milling tool, both the axial rake angle and the radial rake angle can be increased without deteriorating the cutting edge strength or seating rigidity, and thus highly efficient cutting can be performed. , even better cutting accuracy can be obtained.

[Brief explanation of the drawing]

Figures 1 to 9 show an embodiment of the throw-away type milling tool of this invention. Figure 1 is a front view, Figure 2 is a bottom view, and Figure 3 is a milling tool of this example. Figure 4 is a front view showing the chip installed in Figure 3, Figure 5 is a view taken along line _A1 - _A1 in Figure 3, and Figure ₅ is a view taken along line A2-A in Figure 3.
A _2- line view, Figures 6 and 8 are 2nd line views, respectively.
Figures 7 and 9 are enlarged views of part D in Figure 1, Figures 10 to 14 show other embodiments of this invention, and Figure 10 is a front view. 11 is a bottom view, FIG. 12 is a front view showing the chip installed in the milling tool of this example, FIG. 13 is a view taken along line A ₃ - A ₃ of FIG. 12, and FIG. The figure is a view taken along line A ₄ - _{A 4} in Fig. 12, Fig. 15 is a front view showing another example of the milling tool of this invention, and Figs. 16 to 22 are conventional throw-away type milling tools. Figures 16 and 18 are enlarged views of the main parts of the bottom, Figures 17 and 19 are enlarged views of the main parts of the same front, and Figure 20 is an enlarged view of the main parts attached to the above-mentioned milling tool. A front view showing the chip, Fig. 21 is a view taken along the line _A5 - _A5 of Fig.
A ₆ - A ₆ line view and FIG. 23 are cross-sectional views showing the machined surface of a workpiece cut with the above-mentioned conventional milling tool. 20, 40... Tool body, 21... Chip pocket, 22, 41... Chip mounting seat, 23, 3
3, 42... Throwaway tip, 24... Lower surface, 25... Upper surface, 26... Main cutting edge, 27... Obtuse corner portion, 8... Acute corner portion, 29...
Convex curved surface, 32, 34, 35...Side surface, 36...Seating portion, M...Diagonal line, P...Virtual line, X...Axis line, Y...Rotation locus, _C1 , _C2 , _C3 , C ₄ ...Arc radius, A...Axial rake angle, R...Radial rake angle.

Claims (1)

[Scope of utility model registration request] A rectangular plate-shaped throw-away chip whose lower surface is a seating surface is placed on the outer periphery of a tool body that rotates around the axis, and a main cutting edge formed on the ridge of the upper surface is placed on the outer periphery of the tool body. In the throw-away type milling tool, the throw-away tip is mounted with the upper surface as an outer circumferential relief surface, and the throw-away chip has the above-mentioned upper surface as a side view from a direction along a diagonal line connecting the pair of corner portions of the upper surface. , this diagonal line portion is the apex, and an arc is drawn in which the thickness between the upper and lower surfaces gradually decreases from this diagonal line portion toward the other corner portions sandwiching this diagonal line in between, and one of these arcs The arc center of is located on the other arc side from the imaginary line drawn from the diagonal line at right angles to the lower surface, and the arc center of the other arc is located on the one arc side from the imaginary line. A throw-away milling tool, characterized in that it is formed of a convex curved surface, and is mounted on the tool body with the other corner portion positioned on the leading end side in the rotational direction of the tool body.