JP2577014Y2 - Indexable inserts for ball end mills - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a throw-away type ball end mill used in a milling machine or the like, and in particular, a cutting edge configuration of a throw-away tip (hereinafter sometimes simply referred to as a tip) in a ball end mill and a cutting edge of the tip. It relates to improvement of the mounting structure.

[0002]

2. Description of the Related Art Problems to be solved by the prior art and the invention Among the ball end mills having a plurality of cutting edges having an arc cutting edge portion, a solid type made of high-speed steel or cemented carbide, or a cemented carbide cutting edge portion. In the case of a blade type with an alloy brazed, an S-shaped blade with excellent cutting performance by making use of the twist angle of the outer peripheral blade.
Characters are formed approximately. ) Is used.
However, there is no S-shaped blade in the throw-away type due to its shape limitation, and instead, a blade having a convex circular arc curve near the center of the rotation axis has been proposed. (For example, Japanese Utility Model Publication No. 60-100113)
In addition, even in the case of a relatively small diameter having an outer diameter of about 30 mm or less, the development of a two-flute type capable of increasing the table feed amount is strongly demanded from a single-flute type in view of recent high efficiency processing. ing.

[0003] However, in a ball end mill, as compared with a normal square type end mill, the back force, which is the cutting resistance in the axial direction, of the cutting resistance during cutting is increased. Therefore, in the case where the two side surfaces serving as the constraint surfaces of the chip mounting reference surface intersect at an obtuse angle (for example, Japanese Utility Model Application Laid-Open No. 58-22221), the axial back force during cutting is reduced by the side wall of the tool body chip. Without the screw itself,
The heavier the cutting, the easier the tip moves. Therefore, chatter is likely to occur, and it is also difficult to maintain the tip R accuracy before processing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a high-performance throw-away insert which is excellent in cutability, and has high chip mounting strength and mounting accuracy, for use in a ball end mill. The purpose is to do.

[0005]

Means for Solving the Problems To achieve the above object, the present invention relates to a throwaway tip used for a throwaway ball end mill having a rotation trajectory having a substantially hemispherical shape. 4
The circular arc-shaped inclined side surface and the linear inclined side surface connected to the circular arc-shaped inclined side surface are point-symmetric with respect to the chip center mounting hole, and a straight convex portion or a concave portion serving as a chip mounting reference side surface is provided on the bottom surface of the throw-away chip. And wherein the linear projection or recess intersects the linear inclined side surface at an acute angle of less than 90 degrees.

[0006]

According to the invention of the present application, at least the main chip of the chips has a straight inclined side surface on the side intersecting with the arc cutting blade portion and one side surface of the straight convex portion provided on the chip bottom surface, and a chip attachment reference side surface. And since the two side surfaces are attached to the chip seat so that the mounting angle at which the two side surfaces intersect is 90 degrees or less, the cutting resistance at the time of cutting is received by the two side walls of the main body chip seat intersecting at an acute angle of less than the right angle. This makes it possible to significantly improve the chip mounting strength and the chip mounting accuracy. Furthermore, since the arc-shaped blade portions of the main tip and the sub-tip in the bottom view have substantially the same shape, and both have a substantially S-shape, the cutting edge ridge at the time of cutting becomes three-dimensional, and , Smooth cutting can be performed without receiving the mechanical impact in all cutting blades at once. Due to these synergistic effects, an increase in the cutting force caused by smooth cutting can be maintained and improved by improving the mounting of the chip to improve the warpage strength and accuracy.

Further, when the sub-tip is attached to the tip seat in the same manner as the above-mentioned main tip, the position of the tip of the cutting edge of the sub-tip can be made closer to the vicinity of the axial center, and the number of blades due to the sub-tip is increased. It can be used effectively.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show a throw-away type ball end mill according to the present invention, in which a main tip 2 and a sub tip 3 are positioned at approximately 180 degrees with respect to an axis 4 on a tip ball portion of a tool body 1. It is detachably fixed to a chip seat connected to a certain chip pocket portion by a set screw 7 through a mounting hole on the upper surface. That is, the one shown in the drawing is a two-flute type throw-away type comprising a main tip 2 having a cutting edge including an axis center line 4 and one sub-tip 3 having a cutting edge except for an axis center portion. It is a ball end mill.

As shown in FIGS. 4 and 5, the main chip 2 has substantially quarter-circular arc-shaped inclined side surfaces 21a and 21b and a linear inclined surface connected thereto at point-symmetric positions with respect to the center mounting hole. An upper surface 24 which has side surfaces 22a and 22b and is a rake surface between two intersections 23a and 23b between the arc inclined side surface and the linear inclined side surface is a convex cylindrical curved surface having a radius R1, and the upper surface 24 and the arc The line of intersection with the linearly inclined side surface is defined as the cutting edge 25. A linear concave portion 27 is formed on the chip bottom surface 26 which is a plane of the chip 2 by the intersection line 23a.
The mounting angle θ, which is the angle formed by the side linear inclined side surface 22b and the virtual extension, intersects at 90 degrees or less. (Θ = 75 degrees in FIG. 4) The sub chip 3 having the same basic shape as the main chip 2 shows the appearance of the main chip 2 when the main chip 2 is superimposed by a dashed line in FIGS.
As is more apparent, it has a similar shape smaller than the main chip 3 in a top view. By making the upper surfaces of the main chip and the sub chip have a convex cylindrical curved surface, the cutting edge ridges of both chips can have a substantially S shape when viewed from the bottom of the end mill. In addition, this S-shape is formed as a convex cylindrical curved surface between the linear inclined side surfaces 22a and 22b as shown in FIG. 6 even with the size of the radius R1, the same radius R1, and the same radius R1. The S-shaped shape can be made clearer. In this case, the sub chip 3 does not need to be similar to the main chip 2 as shown in FIG.
It is also possible to increase the length of the linear inclined side surfaces 22a, 22b to increase the length of the outer peripheral cutting edge during the chip setting.
This is the scope of the technical idea of the present invention.

As shown in FIG. 9, a chip seat 5 into which the main chip 2 is inserted has a linear inclined side surface 22b of the chip and a linear concave portion 27 of the chip bottom surface 26. On the side wall 51 and the chip seat bottom surface 52, the chip seat bottom convex portion 5 which fits into the linear concave portion 27 of the chip bottom surface 26 so that the chip bottom surface 26 becomes a chip mounting reference surface.
3 is formed at a mounting angle θ (θ = 75 degrees in FIG. 9), and when the main chip 2 is mounted, the side pressure of the set screw 7 is applied through the central mounting hole on the chip upper surface 24 to the side wall 51 and the chip seat bottom surface. The chip 2 is pressed against a side surface 531 located on the side wall 51 side of the projection 53. Therefore, the resistance at the time of cutting can be received by the tip seat side walls 51 and 531 of the tool body 1, the tip 2 can be stably and reliably received in the tip seat 5, and the tip 2 is stably provided. And securely fixed in the chip seat 5. Also, sub chip 3
Are fixed in the chip seat in the same manner as the main chip 2.

Further, as shown in FIG. 10 and FIG. 11, a quadrangular positive tip auxiliary tip 10 is placed on substantially the same rotational locus as the outer peripheral cutting edges of the main tip 2 and the sub tip 3.
By forming the outer peripheral edge by displacing it in the axial direction and fixing it with the set screw 7, the present invention can be applied to a deep cutting process or an operation in which the cutting depth varies. FIG.
When the mounting reference surface of the chip 3 ′ is formed to be a straight inclined side surface 32 b, a short turning side surface 39 b intersecting the straight inclined side surface 32 b with the mounting angle θ of 90 degrees or less, and a bottom surface, In addition to facilitating the processing of the chip seat itself, the processing of the linear convex or concave portion on the bottom surface of the chip seat can be omitted, so that the processing of the chip seat is also facilitated without lowering the mounting strength and mounting accuracy of the sub chip. be able to. However, in this case, since the short turning side surfaces 39a and 39b are provided, as shown in FIG. 13, the cutting edge 351 of the sub tip 3 ', the cutting edge 351 of the main tip 2, and the cutting edge 251 of the main tip 2 are provided. And the cutting edge of the sub-tip 3 does not exist in the range of l, so that the load on the main cutting edge at the time of cutting increases. In the above, the tip 251 of the main chip 2 cutting edge portion is chamfered with a radius r from the outer peripheral side as shown in FIG. 14, or is chamfered straight (not shown).
Alternatively, as shown in FIG. 15, a straight chamfer is formed at an angle β larger than the tangent of the radius R1 from the upper surface 24, which is a rake face, or a curved chamfer (not shown) is formed with a radius smaller than the radius R1. Increasing the edge strength of the cutting edge 251 by combining the outer peripheral side chamfering and the upper surface side chamfering is also within the scope of the technical idea of the present invention, and the same applies to the sub-tip.

Further, as for the linear concave portion or the linear convex portion on the bottom surface of the chip, one linear concave portion 27 has been described. However, as shown in FIG. 18, two linear concave portions are point-symmetric with respect to the center mounting hole. A concave portion 27 may be provided, or a linear convex portion 29 may be provided on the chip bottom surface 26 side as shown in FIGS. Even if two concave portions 27 are provided on the chip side as shown in FIG. 18, if the concave portions 27 are provided symmetrically as described above, one convex portion on the chip seat bottom surface on the main body side is provided. Just need.

[0013]

[Effect of the Invention] The present invention divides the insert in the throw-away type ball end mill into a main insert and a sub insert,
In addition, when viewed from the bottom of the end mill, the cutting edges of the main tip and the sub-tip have substantially the same shape, and both of them have a substantially S-shaped cutting edge as a whole. The entire cutting blade part is not received at once, and the auxiliary tip is provided in addition to the main tip, so the table feed amount of the machine can be increased by the increase in the number of blades, and a higher performance ball It can be an end mill. In addition, the constraint surface of the mounting reference surface of the main chip is one side surface of a linear inclined side surface and a linear concave portion or a convex portion provided on a bottom surface that intersects with a virtual extension line of the side surface at 90 degrees or less. Excellent mounting accuracy. In addition, if the sub-tip has the same mounting structure as the main tip, the tip position of the cutting edge of the sub-tip can be closer to the tip position of the cutting edge of the main tip located at the center of the axis, which is more ideal. A throw-away type ball end mill having an S-shape can be provided.

[Brief description of the drawings]

FIG. 1 is a front view of a throw-away type ball end mill according to the present invention.

FIG. 2 shows a side view of FIG. 1;

FIG. 3 shows a bottom view of FIG. 1;

FIG. 4 shows a front view of a main chip.

FIG. 5 shows a side view of FIG. 4;

FIG. 6 shows a side view of another embodiment.

FIG. 7 shows a front view of a sub chip.

FIG. 8 shows a side view of FIG. 7;

FIG. 9 shows a front view of a chip seat of a main chip.

FIG. 10 is a side view from the lower right of FIG. 9;

FIG. 11 is a front view of a throw-away type ball end mill with an auxiliary tip showing an application example of the present invention.

FIG. 12 shows a side view of FIG. 11;

FIG. 13 is a front view of a modification of the sub chip.

FIG. 14 is a front view of the throw-away type ball end mill when the tip of FIG. 13 is set as a sub tip.

FIG. 15 is a front view showing a curved chamfer from the outer peripheral side of the main chip.

FIG. 16 is a partially omitted front view showing a straight chamfer from the rake face side of the main chip.

FIG. 17 is a side view from the lower right side of FIG. 17;

FIG. 18 is a side view of a modification of the linear concave or convex portion on the bottom surface of the main chip.

FIG. 19 is a side view of a modification of the linear concave or convex portion on the bottom surface of the main chip.

FIG. 20 is a side view of a modified example of the linear concave or convex portion on the bottom surface of the main chip.

[Description of Signs] 1 Tool main body 2 Main tip 3 Sub tip 3 'Modified example of sub tip 3 4 Axis center line 5 Tip seat 10 Auxiliary tip 21a, 21b, 31a, 31b Arc inclined side face 22a, 22b, 32a, 32b Straight line Inclined side surface 23a, 23b intersection line 24 top surface 25 cutting edge 26 chip bottom surface 27 linear concave portion 39a, 39b short side surface 51 side wall 52 chip seat bottom surface 53 chip seat bottom convex portion

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23C 5/10

Claims (1)

(57) [Scope of request for utility model registration] 1. A throw-away insert used in a throw-away ball end mill having a rotation trajectory having a substantially hemispherical shape , wherein the throw-away tip has a substantially quarter-circular arc inclined side surface and a linear inclined side surface connected thereto. Are formed point-symmetrically with respect to the chip center mounting hole, and a straight convex portion or a concave portion serving as a chip mounting reference side surface is provided on the bottom surface of the throw-away chip, and the convex portion or the concave portion is the linear slope. A throw-away tip for a ball end mill, wherein the tip crosses the side face at an acute angle of less than 90 degrees.