JPH1034598A - Blade for rotary cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a cut-in amount such as generating a lock even by large pressing force. SOLUTION: This blade is a blade for a rotary cutting tool to drill a drilled object by cutting an annular groove relating to the drilled object. In at least one of rotational direction before or behind a cutting edge 2, a cut-in limiting means 4 is provided, which has a height lower than the cutting edge 2 to limit a cut-in amount by contact with a cut surface. Even when large pressing force is increased to the drilled object, a cut-in amount per one turn is prevented from exceeding an amount based on a height difference between the cut-in limiting means 4 and the cutting edge 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary cutting tool blade for drilling a large-diameter hole in an object to be drilled.

[0002]

2. Description of the Related Art As a rotary cutting tool for drilling a large-diameter hole in an object to be drilled, there is a so-called hole saw in which a large number of cutting blades are formed all around an opening edge of a cylindrical blade body. is there. An annular groove is cut into the object to be drilled, and a large-diameter hole is formed in the object by cutting until the annular groove penetrates the object to be drilled.

[0003]

In the above-described apparatus, the amount of cut per rotation varies depending on the magnitude of the force pressing the object to be drilled. However, if the amount of cut is too large, locking may occur. There is a problem in terms of safety and workability. The present invention has been made in view of such a point, and an object of the present invention is to provide a blade of a rotary cutting tool that does not have a cutting amount that causes locking even if a pressing force is large. is there.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a rotary cutting tool blade for making a hole in an object to be drilled by cutting an annular groove in the object to be drilled. On the other hand, it is characterized in that it is provided with a cut limiting means which is shorter than the cutting blade and limits the cut amount by contact with the surface to be cut. No matter how large the pressing force against the object to be drilled, the amount of cut per rotation does not exceed the amount based on the difference in height between the cut limiting means and the cutting blade.

[0005] It is preferable that the cutting restricting means be located forward in the rotational direction of the cutting blade than in the case where it is located rearward. Further, it is preferable that the notch restricting means is a restricting blade having a flat top end. Further, it is preferable that the cutting blade has a bent shape in which the chip discharging slit has a rectangular shape.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described. In FIGS. 1 and 2, reference numeral 6 denotes a base provided with a mounting shaft 60. Is protruding. The cutting blade 2 and the limiting blade 4 are attached to one end of the base 6, and the flat blade 3 and the limiting blade 4 are attached to the other end of the base 6. Reference numerals 20, 30, and 40 in the figure denote carbide tips bonded to the blades 2, 3, and 4, and 61 in the figure denotes attachment and fixing of the blades 2, 3, and 4 arranged on the same circumference. It is a screw for. In the illustrated example, each of the limiting blades 4 is disposed forward of the cutting blade 2 in the rotational direction indicated by an arrow in the drawing and forward of the flat blade 3 in the rotational direction, but is disposed rearward in the rotational direction. Is also good.

The blade of this rotary cutting tool is
Is attached to an electric tool such as an electric drill, and drilling of the object to be drilled 7 is performed by rotating the shaft 5 in a state where the shaft 5 is positioned at the center of the hole to be drilled.
By performing cutting with the cutting blade 2 and cutting with the flat blade 3, an annular groove is cut into the drilled object 7, and the annular groove is cut until the drilled object 7 is penetrated. At this time, the cutting blade 2 cuts the outer peripheral side of the annular groove, and the flat blade 3 cuts the inner peripheral side of the annular groove and the bottom of the annular groove.

As is apparent from FIG. 3, the limiting blade 4 has an inclined surface on the front side in the rotation direction and a flat end surface, and it is not possible to cut the drilled object 7 by the rotation. However, the object to be pierced 7
In this state, only the object to be slid slides on the surface to be cut of the object 7 while being pressed. Each of the limiting blades 4 also has a predetermined value x (0.05 to 0.60 m) for the cutting blade 2 and the flat blade 4.
m), the cutting amount by the cutting blade 2 or the flat blade 3 is the amount y by which the limiting blade 4 crushes the pierced object 7 by the pressing force, no matter how much the pressing force is increased. And the predetermined value x, and the value of y is very small, so that there is no possibility that the cut amount becomes too large to lock. In addition, in terms of the reliable limitation of the cutting amount, it is possible to obtain a more preferable result when the limiting blade 4 is disposed in front of the cutting blade 2 and the flat blade 3 in each rotation direction than when the restricting blade 4 is disposed behind.

Further, since the tips of the two limiting blades 4 and 4 are flat, the entire blade does not tilt during cutting, and the value of the crushing amount y can be reduced. As a result, more stable low-load cutting can be performed. Here, a slit 8 for discharging chips is provided between the leading edge in the rotating direction of the cutting blade 2 and the trailing edge in the rotating direction of the restricting blade 4, and the slit 8 is bent in a rectangular shape. As shown in FIG. 4, when a long chip is generated, the chip is bent along the bent shape of the slit 8, and the slit 8 is bent in a rectangular shape. By doing slit 8
Can be widened, and as a result, clogging by chips is less likely to occur.

Further, the above-mentioned blades 2, 3, and 4 are formed as those having the cemented carbide tips 20, 30, and 40 joined to the tips as described above.
For the cutting blades 2 and the flat blades 3, 4 and 3 are not cross-sectional shapes cut along a plane perpendicular to the shaft 5, but are flat plates instead of arc-shaped ones around the shaft 5. Carbide tip 2
The width of 0, 30 secures the required blade width, and the width of the part other than the carbide tips 20, 30 is smaller than the blade width and is set in the annular groove to be cut, so that the flat blade is formed. It does not hinder cutting of the annular groove due to the fact that it is a material. The limiting blade 4 is a carbide tip 4
Although they have almost the same width including zero, they do not hinder cutting because they are also set in the annular groove.
In the case of an arc-shaped cross section, it is very expensive because of its difficulty in manufacturing. However, since each of the blades 2, 3, and 4 used here is a flat plate, the cost is much lower. Can be manufactured.

The shape of the cutting blade 2 is shown in FIG.
When one side shown in FIG. 3 is higher than the other side,
When the piercing object 7 penetrates through the pierced object 7, when the piercing object 7 penetrates through the perforated object 7, as shown in FIG. "
Can be suppressed.

[0012]

As described above, according to the present invention, at least one of the front and rear in the rotation direction of the cutting blade is shorter than the cutting blade, and the cutting restriction means for restricting the cutting amount by contact with the surface to be cut. No matter how large the pressing force against the object to be drilled, the amount of cut per rotation does not exceed the amount based on the difference in height between the cut limiting means and the cutting blade, Therefore, it is possible to stably obtain a cutting state that does not cause locking with a low load, and greatly improves safety and workability.

The cutting restriction means can obtain a preferable result with respect to the restriction of the cutting amount and the stable cutting as compared to the case where the cutting blade is located forward in the rotation direction of the cutting blade is located rearward. Further, it is preferable that the notch restricting means is a restricting blade having a flat top end. Since the amount of crushing of the object to be pierced based on the pushing force is reduced, the cutting amount can be more reliably limited, and cutting in a tilted state is less likely to occur, so that stable cutting is performed. be able to.

Further, when the cutting edge of the cutting blade has a bent shape of a rectangular shape, clogging due to the chip is less likely to occur.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention, in which (a)
Is a plan view, and (b) is a front view.

FIG. 2 is a side view of the same.

FIG. 3 is an explanatory diagram showing the operation of the above.

FIG. 4 is an explanatory diagram relating to the discharge of chips according to the first embodiment.

FIG. 5 is an explanatory diagram of occurrence of a fluff.

FIG. 6 is an explanatory diagram of another example.

[Explanation of symbols]

 2 Cutting blade 4 Limiting blade

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 2, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (4)

[Claims] 1. A blade of a rotary cutting tool for drilling a hole in an object to be drilled by cutting an annular groove on the object to be drilled, wherein the blade is lower in height than at least one of the front and rear directions of rotation of the blade. A cutting edge limiting means for limiting an amount of cutting by contact with the surface to be cut. 2. The blade of a rotary cutting tool according to claim 1, wherein the cutting restricting means is disposed forward of the cutting blade in the rotation direction. 3. The blade of a rotary cutting tool according to claim 1, wherein the cutting restricting means is a restricting blade having a flat front end. 4. The blade of a rotary cutting tool according to claim 1, wherein the cutting blade has a slit-shaped slit for discharging chips.