JPH0140642Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a bit for drilling or grooving wood-based materials, noncombustible materials, plastics, etc.

Prior Art Some router bits that have been widely used in the past have one or both edges formed integrally by machining or brazing, and a bottom edge integrally provided at the tip of the shank by brazing. These require troublesome brazing work, limit resharpening, have a relatively short lifespan, and are not economical. In recent years, a throw-away chip system has been introduced that allows the cutting blade to be replaced, but in order to improve the sharpness of circumferential cutting using the side blades, a clearance angle is attached to the chip attachment. The bottom blade of the throw-away tip can cut the outer periphery of the bottom, but it cannot cut the area near the center. Since the bottom blade is not provided in the center, there is an inconvenience that drilling operations cannot be performed. For this reason, some have a special bottom cutter provided at the tip of the shank, but this has the drawback of requiring a special process for forming the bottom cutter, which increases costs.

Purpose Therefore, the present invention has been made in view of the above, and it is an object of the present invention to provide a router bit which has a side blade and a bottom blade, the bottom blade is easy to form, and is low in cost.

Solution: The present invention is a throw-away chip, in which the tip of the presser plate of the chip is configured as a bottom blade, and the bottom blade is located approximately at the center of the shank.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. At the end of the shank 1 which becomes the blade part, a flat bottom 2 is cut deeper than the center of the shank, and a V-shaped groove 3 is cut in the axial direction and is approximately symmetrical with respect to the diameter. A throw-away tip 7, which has a cutting edge formed on the V surface 4 of the V groove 3, with cutting blades formed on both sides as side blades 5 and at the tip as a bottom blade 6, positions the cutting edge of the side blade 5 toward the V groove 3 side. and is fixed to the shank 1 with bolts 9 via a presser plate 8 having a trapezoidal cross section. This presser plate 8 has a trapezoidal surface on its distal end, which is tapered obliquely from the bottom side toward the top side, and the top side is formed with an acute-angled cutting edge that acts as a bottom edge 10. In addition, there is a rake surface 11 on the bottom side of the side that presses down the throw-away tip 7 to improve the flow of chips, and a V surface that presses down the throw-away tip 7 has a rake surface 11 that presses down the throw-away tip 7 using centrifugal force.
A protruding strip 12 that engages with a U-groove (described later) is formed to prevent it from popping out. The angle of the V surface is formed into a V shape that is equal to or slightly larger than the angle of the V groove 3, so that the throwaway tip 7 can be securely fixed when installed, and the bottom blade 10 is aligned with the center line of the shank 1. It is formed in such a width that it is located at or near it. When the presser plate 8 fixes the throw-away chip 7, the bottom blade 10 of the presser plate 8 is positioned in a slightly retracted state with respect to the bottom blade 6 of the throw-away chip 7. In this way, since the bottom blade 6 slightly protrudes from the bottom blade 10, when the router bit is rotated and moved laterally in the groove forming direction during groove machining, the bottom machined surface of the center part by the bottom blade 10 is cut by the throw-away tip 7. Since the finishing process is performed by the sharp bottom edge 6 of the presser foot, there is no problem of poor surface finish due to poor sharpness due to the rake angle of the bottom edge 10 being 0 degrees or a negative angle. There is no need to sharpen the bottom edge 10 of the plate 8. In this embodiment, the throw-away tip 7 has a rectangular shape with a U-groove 7a extending to both ends in the longitudinal direction cut in the center of the surface width on the rake face side of the blade, that is, on the presser plate side to be described later. Figures 7 and 8 show that the U-groove 7'a in the longitudinal direction of the throw-away tip 7' is not cut all the way to both ends, but only in the center, and the bottom edge part is shaped like a diamond with a deep outer periphery. It was formed in By doing this, the U-groove is completely or mostly covered, so that chips do not get stuck in the gap between the U-groove and the convex strip of the holding plate during drilling, and the chips do not accumulate in the U-groove, and there are parts of the bottom of the hole that cannot be cut. In addition, the protrusions on the presser plate engage the U-groove of the throw-away tip to prevent the throw-away tip from flying out due to centrifugal force. Of course, this throw-away tip 7' can also be used for a router bit in which the bottom blade 10 is not formed on the holding plate 8. The bottom blade may be brazed to the holding plate.

Effects As detailed above, in the present invention, the bottom blade for cutting near the center of the hole is formed on the presser plate itself that fixes the throw-away tip, so the configuration of the bottom blade is very easy, and it can be used for drilling or drilling. Groove machining is also possible, and there is no need to provide a special part in the shank part as the bottom edge of the center, so the holding plate can be hardened and tempered using hardened steel, or low carbon steel can be surface treated to give it hardness. It has the characteristic of being economical because it can be handled by

[Brief explanation of drawings]

Figure 1 is a side view of the router bit of the present invention;
The figure is a front view of the same, Figure 3 is a side view opposite to Figure 1, Figure 4 is a bottom view of the same, Figure 5 is A-A of Figure 2.
6 is a plan view of another embodiment of the throw-away tip, FIG. 7 is a sectional view taken along line B-B in FIG. 6, and FIG. 8 is a sectional view taken along line C-C in FIG. 6. be. 1...Shank, 5...Side blade, 6...Bottom blade,
7, 7'... Throwaway tip, 8... Presser plate, 10... Bottom blade.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A throw-away tip having side blades and a bottom blade that takes charge of cutting the outer circumference of the bottom is held in a vertical V-groove of the shank that is deeply cut beyond the center position. In order to do this, the top surface of a presser plate having a trapezoidal cross section that is inserted and fitted into the V-groove and fixed with bolts together with the throw-away tip is positioned at or near the center line when fitted and fixed, and the top surface is placed inside the bottom. A router bit with a bottom blade is characterized by having a bottom blade that takes charge of cutting the peripheral part. (2) A router bit with a bottom blade according to claim 1, wherein the bottom blade of the holding plate is integrally formed. (3) A router bit with a bottom blade according to claim 1, wherein the bottom blade of the holding plate is formed on a bonded tip. (4) A router bit with a bottom blade according to claim 1, wherein the bottom blade of the holding plate is slightly retracted from the bottom blade of the throw-away tip.