JPS5835370Y2 - Spiral blade ball end mill - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a spiral blade ball end mill that has excellent cutting performance and a strong chip attachment.

Conventionally, the cutting edge of an end mill has been formed into a straight line or a shape close to it in the radial direction from the center, and for this reason, when cutting, the cutting edge advances at the same rotational angle phase from the center to the outer periphery. , and cutting is performed by pressing the chips in the forward direction of the cutting edge, so the chips are compressed on the rake face, the cutting resistance is large relative to the unit length of the cutting edge, and the chips tend to weld. It also causes chipping, and the cutting edge wears out quickly, making it difficult for high-speed, heavy-duty cutting of steel.

In addition, in recent years, work materials have come to contain many difficult-to-cut and high-hardness materials, and it has become necessary to use cemented carbide for end mills, but in the case of cemented carbide, When cutting steel at a speed below a certain speed, there is a problem in that the cutting edge is damaged due to chips or built-up cutting edges being crimped or falling off.

For this reason, when cemented carbide is used for an end mill, the cutting speed near the center is slow even if the rotational speed of the tool is high, so damage to the cutting edge near the center impedes cutting performance.

Furthermore, the conventional cutting edge shape does not allow smooth discharge of chips generated during steel cutting, and has the disadvantage that the feed rate of the end mill cannot be increased.

Ota. Since the tip is not firmly attached to the main body, there is a problem in that the attachment part of the tip gets damaged during use.

In view of these points, it is an object of the present invention to provide an end mill with a securely mounted tip and excellent cutting performance.

Hereinafter, the present invention will be explained with reference to drawings of embodiments.

A pair of tips 2 and 3 are fitted into the grooves of the shank 1 of the end mill and fixed thereto by brazing or the like.

As shown in FIG. 3, when viewed from the bottom, the tip 2 has a starting end 6 near the center of rotation, has a rising portion, has a curve that is convex in the rotation direction, and has a curve that extends from the cutting edge curve at the outer periphery. The cutting edge curve at the center has a larger curvature.

The cutting edge of the chip 3 is such that the starting end 50 of the cutting edge 5 is located at a position slightly away from the center of rotation and extends to the outer periphery in a shape symmetrical to the cutting edge curve of the cutting edge 4.

7 is a relief groove of the cutting edge, and 9 is a back metal through which the tip receives force from the workpiece during cutting.

The rake face 20 of the insert 2 is curved in the radial direction along the curve of the cutting edge 40 and straight in the axial direction, so that the normal mounting method is based on the intersection of the rake face 20 and the relief groove 7. The line is a straight line 73 as shown in phantom in FIGS. 1 and 5.
becomes.

That is, both cylinders intersect at a certain angle.

In that case, the force in the direction of arrow A received from the workpiece during cutting is supported by the back metal 9,
At the same time, the point of application of the force A is at the edge of the chip, whereas the supporting force of the back metal 9 is at the center of the chip, creating a couple force, A reaction force in the direction of arrow B is generated.

This force causes stress concentration to occur at the intersection line 73 during long-term use, and this results in damage to the intersection line 73.

However, in the present invention, as shown in FIGS. 4 and 5, the intersection of the rake face 20 and the escape groove 7 is made continuous by a curved surface TO.

Therefore, the force in the direction of arrow B that occurs during cutting is received by the entire curved surface 70, and stress concentration does not occur.
In addition, since the curved surface 700 also acts as a back metal against the force in the direction of arrow B, the holding strength of the chip is significantly improved.

Further, the chips 10 generated by cutting are elongated along the cutting surface 20, then gradually bent at the curved surface 70, and transferred to the relief groove 7, so that the chips can be smoothly discharged.

The above configuration is similarly adopted for the chip 3 side.

Further, the configuration of the present invention can be adopted not only in the case of such a two-blade tip but also in a single-blade end mill.

When cutting is performed with this end mill, the cutting into the workpiece starts from the center point, and the cutting gradually moves to the outer circumference, and at the same time, even if the button is pressed in the rotational direction, it moves in the opposite rotational direction.

That is, since the cutting edge has a spiral shape, the chips move toward the outer circumference as the end mill rotates.

With conventional cutting blades that are formed radially and linearly from the center point, the cutting blade always advances at the same rotational direction phase from the center to the outer circumference 1, and the start of cutting at each point on the cutting blade is at the same rotational direction phase. In addition, the cutting resistance is large because the chips are pushed perpendicularly to the cutting edge in the direction of the cutting blade's progress, and this causes the chips to be crimped onto the tip of the knife, preventing smooth cutting. was.

However, in the above structure, since the cutting blade 4 is inclined with respect to its advancing direction, the chips are sequentially pushed out in the outer circumferential direction, and are not pressed against the cutting blade, so they are smoothly discharged. A good cut is made.

Furthermore, because the spiral shape of the cutting blade has a large curvature near the center point, the cutting blade can reliably cut even though the cutting speed is slow, and it does not slip upwards like conventional products. Good cutting can be performed without causing any damage.

As explained above, the present invention aims to improve the cutting performance especially in the center by adopting the spiral array shape, and also improves the holding strength of the chip by providing a curved surface at the connection part between the rake face of the chip and the relief groove. It was planned.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the present invention, FIG. 2 is a right side view thereof, FIG. 3 is a bottom view thereof, and FIG.
A sectional view taken along line IV, and FIG. 5 is a partially enlarged view of FIG. 4. 1... Body, 2, 3... Chip, 4,
5... Cutting edge, 7... Relief groove, 70...
····curved surface.

Claims (1)

[Scope of utility model registration request] A ball end mill has a chip with a cutting edge fixed to the shank, and the chip is fitted into the groove of the shank, and the rake face of the chip and the inner surface of the chip relief groove are continuous on a curved surface, and the chip is The cutting edge is constructed such that its starting end is located near the center of rotation, forms a convex curve in the direction of rotation, and the cutting edge curve at the center has a larger curvature than the cutting edge curve at the outer periphery. Features a spiral blade ball end mill.