JP2005001072A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill which can efficiently produce a deep hole having excellent straightness in a workpiece made of non-ferrous metal having low toughness, such as brass. <P>SOLUTION: The drill 1 has one straight cutting edge 4 radially extending from the center of the tip end toward the outside, one straight flute 7 which serves to discharge chips and has a sectorial cross section, and a point angle θ. Further, the drill 1 has a short ridge 6 at its tip end, the ridge extending from the inside end of the cutting edge 4 in the opposite direction of the cutting edge so as to shift the trailing end of a relief surface 5, in the direction of the rotation of the drill, from the inner end portion of the cutting edge 4, and a drill body 2 having a sectorial cross section having a sector angle of 250° and over but less than 270°. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drill suitable for drilling a non-ferrous metal with low viscosity, for example, a copper alloy typified by brass (brass) or free-cutting aluminum.
[0002]
[Prior art]
For example, a flat groove drill is generally used for drilling brass, and a half-moon half-moon drill or a gun drill with a single blade is used for deep hole machining.
[0003]
[Problems to be solved by the invention]
The flat groove drill has a chisel blade in the center, so the thrust rises and the drilling efficiency does not increase. The shape is also complicated, and there is a drawback that it is more expensive than a half-moon drill.
[0004]
On the other hand, the half-moon drill is not as high as a flat groove drill, but has a high thrust and has a problem in machining efficiency and straightness during machining. With this half-moon drill, especially a thin drill with a diameter of less than 5 mm, for example, when trying to make a hole in brass with a diameter ratio depth of about 10 times, if there is no pilot hole or guide hole, it will be bent in the middle As a result, the cut-out position of the drill greatly deviates from the target point, and decent machining cannot be performed. This half-moon drill has a problem in terms of chip discharge, so step feed processing is performed, but this method does not increase drilling efficiency.
[0005]
A pilot hole or a guide hole is indispensable for a gun drill, and the time required for processing the hole becomes a loss time, and the total drilling efficiency is lowered.
[0006]
An object of the present invention is to enable a straight deep hole to be efficiently drilled in a non-ferrous metal such as brass with low viscosity without applying a step feed directly with a drill without a chisel blade even if there is no center hole. .
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, in the present invention, one straight cutting edge extending radially outward from the center of the tip, a single fan-shaped straight groove for discharging chips, and a tip angle Furthermore, the tip has a straight ridge line with a very small length extending from the inner end of the cutting edge in the direction opposite to the cutting edge and allowing the end of the drill rotation direction of the flank to escape from the inner end of the cutting edge. The present invention provides a drill having a fan shape in which a cross section of the body has an opening angle of 250 ° or more and less than 270 °.
[0008]
This drill can be expected to have a particularly excellent effect when machining a hole having a diameter ratio depth of about 10 to 15.
[0009]
The tip angle of this drill may be 120 °, the same as the standard tip angle of the drill.
[0010]
Further, the length of the ridge line at the tip provided to be connected to the inner end of the cutting edge is preferably about 0.5 mm to 1 mm.
[0011]
In addition, the opening angle of the straight groove is preferably about 100 ° to 105 ° (the fan cross section angle of the body section is about 255 ° to 260 °).
[0012]
[Action]
The drill of the present invention has a fan-shaped cross-sectional shape with a body having a spread angle of 250 ° or more and less than 270 °, and the body cross-sectional area when compared with a drill having the same diameter is larger than that of a half-moon drill. Therefore, the rigidity is high and the body is less bent during processing.
[0013]
The drill of the present invention is a single-blade straight blade drill, but has no chisel blade in the center unlike a general straight blade drill. In addition to this, the ridge line extending in the opposite direction to the cutting edge from the center of the tip, that is, the ridge line that is the same length as the cutting edge in the half-moon drill, has a very small length (about 1 mm at the maximum). There is almost no increase in thrust due to the chisel blade.
[0014]
Furthermore, since the drill of the present invention has a ridge line with a very small length at the tip, and the end of the flank drill in the rotation direction is separated from the inner end of the cutting edge (is released), the drill tip of the drill with respect to the work material Deterioration of biting property and biting property and deterioration of sharpness of the inner edge of the cutting edge can be suppressed.
[0015]
In addition, the straight groove has a fan-shaped cross section, which improves the evacuation performance of the chips that are sheared and discharged (since the half-moon drill has a too wide cross section, the flow output of the chips is lost during the process. And the accumulated chips prevent the discharge of subsequent chips).
[0016]
Due to the above actions and effects, the drilling efficiency is improved, and the bending of the hole is suppressed even in deep hole machining.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. The illustrated drill 1 includes a body 2 in which a first large diameter portion 2b is connected to the rear portion of the small diameter portion 2a, and a second large diameter portion 2c is connected to the end of the first large diameter portion. And a stepped drill having an integral shank 3.
[0018]
A tip angle θ is attached to the tip of the body 2 (tip of the small diameter portion 2a). Further, at the tip of the body 2, there is one cutting edge 4 extending in the radial direction from the tip center (rotation center) O, and the inner edge of the cutting edge 4 on the tip center O in the direction opposite to the cutting edge 4. Is provided with a ridge line 6 extending from the inner end position of the cutting edge 4 to the end of the flank 5 in the direction of drill rotation, and a single straight groove 7 having a spread angle α on the outer periphery of the body 2. ing. The bottom of the straight groove 7 extends substantially parallel to the axial center of the drill from the outer end of the ridge line 6 to the middle of the length of the first large-diameter portion 2b, and from the middle of the first large-diameter portion 2b to the second large-diameter portion 2c. Rounded up toward the outer periphery. The rake face has a surface roughness in which the generated chips are sheared by friction with the rake face.
[0019]
Note that a cutting edge 8 perpendicular to the shaft center for machining the bottom of the seat hole is provided at the tip of the first large diameter portion 2b, and at the tip of the second large diameter portion 2c having the same diameter as the shank 3. Is provided with a chamfering blade 9 having an inclination angle β = 45 ° for chamfering the opening edge of the seat hole.
[0020]
The drill 1 has a tip angle θ = 120 °, a spread angle α = 100 ° of the straight groove 7, a length s = 0.8 mm of the ridge line 6, and a centering amount of the cutting edge = 0.01 to 0.02 mm. Has been.
[0021]
Other dimensions of the exemplary drill are as follows: small diameter outer diameter D1 = φ4.00 (unit is mm, the same applies hereinafter), first large diameter outer diameter D2 = φ6.00, second large diameter portion and shank The outer diameter D3 = φ8.0, the small diameter portion length L1 = 42, the first large diameter portion length L2 = 9.5, the second large diameter portion length L3 = 10, and the total length L = 120. It is only an example.
[0022]
As a result of making a drill of such dimensions (material: Z-type ultrafine cemented carbide) and making a through hole with a countersink in brass, the depth of the hole processed into the small diameter portion 2a is the diameter ratio (L1 / Despite having about 10 in D1), a hole with good straightness could be efficiently processed without providing a pilot hole or guide hole and without applying step feed. The same was true for drills with a specific hole depth of 15. Moreover, the same result was obtained also about free-cutting aluminum, and it confirmed that there existed an effect in the deep hole processing of a non-ferrous metal with little stickiness not only in brass. The chips were finely sheared and discharged well, and no clogging occurred.
[0023]
【The invention's effect】
As described above, the drill according to the present invention has a fan-shaped cross-sectional body having a spread angle of 250 ° or more and less than 270 °, and thus has high rigidity. Further, since there is no chisel blade and a ridge line with a very small length extending from the inner end of the cutting edge in the direction opposite to the cutting edge is provided, the thrust is small and the biting property to the work material is good.
[0024]
For this reason, if the work material is a non-ferrous metal that is relatively soft and has low viscosity, such as brass, it is efficient even with deep hole machining without a pilot hole or guide hole and without step feed. Can be processed well.
[0025]
The drill of the present invention is simple in shape and easy to manufacture, and can be provided at a low cost.
[Brief description of the drawings]
FIG. 1 is a side view of a drill according to an embodiment. FIG. 2 is an enlarged front view of the same drill.
DESCRIPTION OF SYMBOLS 1 Drill 2 Body 2a Small diameter part 2b 1st large diameter part 2c 2nd large diameter part 3 Shank 4 Cutting edge 5 Relief face 6 Ridge line 7 Slate groove 8 Cutting edge 9 Chamfering edge

Claims (2)

A straight cutting edge extending radially outward from the center of the tip, a straight groove having a fan-shaped cross section for discharging chips, a tip angle, and an inner end of the cutting edge It has a ridge line with a minute length that extends from the inner edge of the cutting edge and extends in the direction opposite to the cutting edge from the drill rotation direction of the flank face, and has a body cross section of 250 ° or more and less than 270 °. A fan having a fan shape. The drill according to claim 1, wherein the drill is configured as a stepped drill having a large-diameter portion for processing a seat hole having a diameter specific length of 1 or more behind a small diameter portion having a diameter specific length of 9 or more.

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