JPH0524490Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a boring drill with a carbide tip used in a wood drilling machine.

Prior Art In order to drill a clean circular hole in wood, a center drill and a hair cutting blade are required in addition to the bottom cutting blade, and with carbide boring drills, generally the flat tip is embedded in a straight groove on the diameter. Approximately 1mm from the bottom cutting blade
The kebiki blade is set high, and is about 1 ~ higher than the kebiki blade.
The central aperture is set 2 mm higher, and three cutting blades of different heights are formed almost in a straight line as shown in Figures 11 to 13, and the hair blade has a ridge line on the diameter line and a It is formed into a high triangular mountain shape.

Because the three cutting blades were arranged in this way, the resharpening of the awl relied on the manual dexterity of a skilled worker who held the awl by hand and used a grinder equipped with a diamond grindstone.

Problems that the invention aims to solve: Because the shape of the boring drill is complex, even if each part can be polished with a grinder, the setting time must be changed each time it is ground, so the setting time is longer than the polishing time. It was inefficient work.

Also, manufacturing a dedicated regrinding machine is uneconomical in terms of cost, so it naturally relies on the manual labor of skilled workers. It was not easy to finish it in a perfect shape. In addition, manual operation lacks accuracy, and because the hair-pulling blade is made thicker for strength, there is a problem in that burns occur around the drilled hole, impairing the finish.

Means for Solving the Problem A Δ-shaped protrusion 11 is provided on the edge along the outer periphery of the rake face 9 of the bottom cutting blade 7, and the cross section perpendicular to the axis is approximately Δ-shaped, and the tip faces the direction of rotation. The intersection point between the extended surface of the flank surface 8 of the blade 7 and the ridge line 10 on the cutting outer diameter of the Δ-shaped convex portion 11 is formed on the hair pulling blade 12, and the hair pulling blade is an extended surface of the flank surface of the bottom cutting blade. It is located above.

Embodiment 1 In Figs. 1 to 3, following the shank part 1 made of carbon steel, a deep groove 3 is cut in the axial direction of several mm in the center diameter direction at the tip of the body part 2. is a long section parallel to the axis at a position that slightly straddles the second quadrant while leaving a part of the first quadrant in the cross section perpendicular to the axis, and a position that slightly straddles the fourth quadrant while leaving a part of the third quadrant symmetrical to this. A chip discharge groove 4 whose bottom covers the groove 3 is cut close to the shank portion 1. A carbide chip 5 having a Z-shaped right-angled cross section is firmly fixed to the deep groove 3 by insertion brazing or adhesion. At the center of the tip of the carbide tip 5, a central cone 6 in the form of a cone or square pyramid is protruded, and bottom cutting blades 7, 7 are formed on the same plane on both sides of the central cone 6. A Δ-shaped convex portion 11 is formed on the edge along the outer periphery of the surfaces 9, 9, with a cross section perpendicular to the pyramid axis being approximately Δ-shaped, and the tip of Δ facing the rotation direction. The flanks 8, 8 of the bottom cutting blades 7, 7 are formed to be inclined to the central axis of the cone, and the extended surfaces of the flanks 8, 8 and the ridge lines 10, 10 of the edges of the Δ-shaped protrusions 11, 11 The intersection point is formed on the hair pulling blades 12, 12. Therefore, the hair pulling blades 12, 12 are formed higher than the bottom cutting blade 7 due to the slope of the flank 8, and in this example, are approximately 1 mm higher. The central cone is higher than the hair cutting blade 12, and in this example, is formed 1 to 2 mm higher.

Embodiment 2 In FIGS. 4 to 6, the same parts as in Embodiment 1 are denoted by the same reference numerals, and the explanation thereof will be omitted. The difference is that a carbide tip 21 having a slightly larger diameter is fixed to the tip of the body portion 2 of the drill by brazing or butt-jointing with an adhesive. In this case, the number of steps for forming the deep groove 3 can be omitted.

Embodiment 3 In FIGS. 7 to 9, the difference from Embodiment 2 is that the chip discharge groove 22 of the body 2 is twisted, and the rake face 23 of the carbide chip has the same helix angle as an extension of the twisted groove. This feature allows for good chip discharge.

Function: The shank portion 1 of the boring drill of this embodiment is inserted and fixed into the main shaft of a woodworking drilling machine, and holes are bored for dowel joining when assembling furniture, etc., for example. Rotate the main shaft and lower it into the workpiece. First, align the most protruding central awl 6 at the predetermined hole position, fix the awl so that it does not run out while drilling a small hole, and as it goes deeper, the next highest hair Cut the outer periphery of the hole with the pulling blades 12, 12. Since the rake blade 12 has a rake angle with respect to the outer circumferential surface, the inner circumferential surface of the machined hole can be cut without causing burns due to friction. As the hair pulling blade 12 digs in, the bottom cutting blades 7 scrape the inside of the hole and the chips are discharged out of the hole through the rake face 9 and the chip discharge groove 4.

When it becomes necessary to re-sharpen the drill bit due to long-term machining, the drill bit is attached to an indexing device that is installed on the table of a tool grinder equipped with a diamond cup grinding wheel and can index the circumference of the boring drill into equal parts. .

The diamond cup grindstone shown in FIG. 10 is positioned at W ₁ with respect to the bottom cutting blade 7 in line with the slope of the flank 8. Since the tip of the hand-pulling blade 12 and the flank 8 of the bottom cutting blade 7 are on the same plane, the grindstone is rotated to polish the flank 8 and the hair-pulling blade 12 at the same time.
Next, the boring drill is turned 180° and the other bottom cutting blade 7 and hair pulling blade 12 are finished in the same manner. Next, a diamond cup grinding wheel is positioned at W ₂ with respect to the central cone 6, and the boring cone is rotated to grind into a cone, or alternatively, the boring cone is rotated by 90 degrees to polish into a square pyramid.

Effects As detailed above, the present invention provides a Δ-shaped protrusion on the outer periphery of the rake face of the bottom cutting blade, and the intersection point between the extended surface of the flank of the bottom cutting blade and the ridgeline at the tip of the protrusion is Since it is formed on the blade, the tip of the hair-pulling blade and the flank of the bottom cutting blade are located on the same plane, allowing for polishing and finishing at the same time in the same polishing process, reducing polishing time and setup time. I can do it. Furthermore, by setting it on a tool grinder, even an unskilled person can easily and accurately grind the tool. Furthermore, since a rake angle is formed on the outer circumferential surface of the hair cutting blade, there is no burning on the inner surface of the machined hole, resulting in a number of effects that allow beautiful machining.

[Brief explanation of the drawing]

Figure 1 is a side view of the first embodiment of the boring drill of the present invention, Figure 2 is its end view, Figure 3 is a side view of the tip shifted by 90 degrees from Figure 1, and Figure 4 is the actual implementation. Example 2 is a side view, FIG. 5 is an end view, FIG.
The figure is a side view of the third embodiment, FIG. 8 is an end view thereof,
Figure 9 is a side view of the tip shifted by 90 degrees from Figure 7, Figure 10 is a diagram showing the polished state, Figure 11 is a side view of a conventional boring drill, Figure 12 is its end view, FIG. 13 is a side view of the tip section shifted by 90 degrees from FIG. 11. 1...Shank part, 2...Body part, 4, 22
...Chip discharge groove, 5, 21...Carbide chip, 6...
...center drill, 7...bottom cutting blade, 8...flank surface, 9,
23... rake face, 10... ridge line, 11... Δ-shaped protrusion, 12... hair pulling blade.

Claims (1)

[Scope of utility model registration request] In a wood boring drill with a carbide tip, which has a central drill, a bottom cutting blade that extends from the center drill toward the outer periphery on both sides, and a hair-pulling blade on the outer periphery that extends from the bottom cutting blade, A protrusion with a substantially Δ-shaped cross section perpendicular to the axis and whose tip faces the direction of rotation is provided on the edge of the ivy, and the intersection of the extended surface of the flank of the bottom cutting blade and the ridge line on the cutting outer diameter of the protrusion is A boring drill for woodworking, characterized in that the hair cutting blade is formed on a hair cutting blade, and the hair cutting blade is located on an extended surface of the flank of the bottom cutting blade.