JPS6317609Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a throw-away type ball end mill, and particularly allows the use of two cutting blades in a small diameter end mill.

Conventionally, as this type of throw-away ball end mill, for example, Japanese Utility Model Application Publication No. 54-21894,
This method is disclosed in Japanese Utility Model Application Publication No. 54-21895. The throw-away tip seen in these publications has an approximately elliptical shape with approximately 1/4 circular cutting edge ridges formed at both ends in the longitudinal direction, and when attached to the tool body, the elliptical tip Since the axial width is large, the non-cutting blade extends beyond the axis center line, and the longitudinal length is unexpectedly large. Therefore, in the throw-away tip shown in the above-mentioned publication, the space occupied by the tip seat is large, and it cannot be applied to small-diameter products with a cutting edge diameter of 12 mm or less.

On the other hand, small-diameter ball end mills generally have problems such as low tool rigidity and cutting edge strength.
The one-cutting blade type had problems such as being less economical.

For these reasons, there is a demand for the development of a small-diameter throw-away ball end mill that has a two-cutting blade configuration and is improved so that the mounting rigidity of the throw-away tip is increased.

The present invention was developed in view of the above points, and a throw-away tip with an approximately 1/4 circular cutting edge is installed in the tip seat provided at the tip of the rod-shaped tool body. For ball end mills that are installed with the starting end of the cutting blade located near the center of the shaft, by improving the cutting blade configuration based on the shape of the throw-away tip, we have ensured high tool rigidity and a two-cutting blade configuration. It was designed so that

An embodiment of the ball end mill of the present invention will be described below with reference to the drawings.

In FIGS. 1 to 3, reference numeral 1 denotes a rod-shaped tool body, and a throw-away tip 3 is received in a tip seat 2 having a substantially triangular shape provided at the tip of the tool body. .

As clearly shown in FIGS. 4 and 5, this throw-away tip 3 has one approximately quarter-circular cutting edge 4 formed on each of its front and back surfaces. The cutting edge 4 involved in cutting is such that when the throw-away chip 3 is received in the chip seat 2, the cutting edge starting end 5 is located near the axis center of the tool body 1, and the cutting edge end is located near the axial center of the tool body 1. It is located on the outer periphery.

The chip seat 2 has one side wall 6a formed as a flat surface, and the other side wall 6b formed as a concave curved surface of approximately 1/4 circle. On the other hand, the flat throw-away chip 3 has three side surfaces 7a,
Consisting of 7b and 7c, one side 7a is flat,
The remaining two side surfaces 7b and 7c are approximately 1/4 circular convex curved surfaces. Further, a cutting surface 8 is interposed at the connecting portion between the two convexly curved side surfaces 7b and 7c, thereby eliminating mutual interference of the cutting edge 4. In other words, when damage occurs to the cutting edge 4 as shown in FIG.
If the damage spreads to the unused cutting edge 4 located on the side wall 6b side, mutual interference will occur, and the unused cutting edge 4 can no longer be used due to the damage. It was avoided.

Further, the cutting edge ridges 4 are symmetrically formed in an eccentric relationship, one each on the side surfaces 7b, 7c and the front and back surfaces, each having the same radius R. Also,
When the throw-away tip 3 is installed in the tip seat 2, the rake angle θ in the axial direction is set to a negative angle, thereby increasing tool rigidity.

In addition, in the illustrated case, the throw-away tip 3 is installed by inserting the setscrew 10 from the center mounting hole 9.
Insert the screw into the bottom surface 11 of the chip seat 2.
This is done by screwing into a screw hole 12 drilled in the. However, the attachment means is not limited to this, and various other means may be used, such as a presser foot, an eccentric pin, or a double clamp combining both. This means that the throw-away tip 3 can be applied even when the central mounting hole 9 is not drilled.

Also, the two sides 7 of the throwaway tip 3
b and 7c form two-stage flanks, which, as can be seen from FIG. 3, are designed especially for small-diameter objects. Therefore, even among small diameter products, if the outer diameter of the cutting edge is large, for example around 12 mm, only the primary flank surface is required.

As explained above, the present invention improves the cutting edge configuration of the throw-away tip 3, and therefore has the following effects.

First, the cutting edge structure of the throw-away tip 3 is rational and has high strength. this is,
This is because although the cutting edge 4 has two corners, it can be applied to small-diameter products, and interference between the cutting edges is also avoided by the presence of the cutting surface 8. In addition, since the shape is similar to a bulging triangle and is close to a circle, it can sufficiently withstand cutting resistance.

Second, tool rigidity is increased. This is because the throw-away tip 3 is constrained on two sides by the side walls 6a and 6b of the tip seat 2, and is fixed at a negative axial rake angle θ, so the tool body can be made thicker. It is from.

Thirdly, cutting performance is high. this is,
This is because effective cutting was achieved when the invented product with a cutting edge diameter of φ10 mm was mounted on a machining center to perform curved surface machining. That is, when a work material made of S55C was curved, the average flank wear was V _B =0.51 mm after 103 minutes of cutting (cutting length of 37.1 m). In this case, the cutting speed is
The speed was 110 m/min, the feed rate was 0.1 mm/tooth, the depth of cut was 1.0 mm, and the pick feed was 1.0 mm.

On the other hand, the design limit of the conventional product shown in the above-mentioned Japanese Utility Model Publication No. 54-21894 was a cutting edge diameter of φ10 mm, but when cutting under the above cutting conditions, the vibration was so great that cutting became impossible immediately. It is from.

[Brief explanation of drawings]

Fig. 1 is a front view showing one embodiment of the ball end mill of the present invention, Fig. 2 is an enlarged bottom view thereof, and Fig. 3 is an enlarged bottom view of the ball end mill.
The figure is a partially enlarged side view, Figure 4 is a front view of the throwaway tip, and Figure 5 is a
Its side view, FIGS. 6a and 6b, are diagrams for explaining damage to the cutting edge of the throw-away tip, and a is a front view;
b is a side view from diagonally below the right side. 1... Tool body, 2... Chip seat, 3... Throwaway tip, 4... Cutting edge ridge, 5... Cutting blade starting end, 6a, 6b... Side wall, 7a, 7b, 7c...
Side, 8...cut surface.

Claims (1)

[Claims for Utility Model Registration] A throw-away tip 3 with an approximately 1/4-circular cutting edge 4 is installed in a tip seat 2 provided at the tip of the tool body 1 having a rod shape. It is installed so as to form a negative rake angle θ in the axial direction, and the cutting edge starting end 5 of this throw-away tip 3 is located near the axial center of the tool body 1, and the cutting edge end is located near the axial center of the tool body 1. In a ball end mill that can participate in hemispherical cutting by being located on the outer periphery side, the tip seat 2 has a bottom surface 1 having a substantially triangular shape.
1, two side walls 6a and 6b are formed, and one side wall 6a is flat,
The other side wall 6b has a substantially 1/4 circular concave curved surface, and when the axis center line of the tool body 1 is taken as a reference, the side wall 6a exhibiting one plane is located at the cutting edge 4.
The throw-away tip 3 has a diagonal positional relationship toward the outer circumferential side on the opposite side, and the other side wall 6b exhibiting a concave curved surface is in a positional relationship that is substantially perpendicular to the axial center line of the tool body 1. one side surface 7a exhibiting a flat surface to fit the chip seat 2;
and two side surfaces 7 exhibiting approximately 1/4 circular convex curved surfaces.
b, 7c, and a cut surface 8 is formed at the connecting portion of the side surfaces 7b, 7c exhibiting convex curved surfaces, and the intersection of the front and back surfaces of the throwaway tip 3 and the side surfaces 7b, 7c. A ball end mill characterized in that two cutting edge ridges 4 each having an eccentric center point and having equal radii R are formed symmetrically, one on each side of the front and back surfaces.