JPH0115465Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a reamer with a drill, which is suitable for finishing a pilot hole formed with a drill or the like using a reamer that is rigidly chucked on a machine. In particular, it concerns a super left-handed reamer with a large helix angle.

(Prior art) Conventionally, this type of so-called super-torsion reamer with a large helix angle was developed by the Japanese Utility Model Publication No. 53-5278 and the Utility Model Publication No. 5278 (1983).
70922 has already been proposed. The former is equipped with an end mill blade with a straight groove formed on the cutting edge of the end mill, and then a reamer body with a super left-handed twist and a right-handed helix angle, with a slightly larger diameter than the end mill blade. In this example, a bevel corner and a second bevel are formed, and a bevel and relief angle are also formed in the reamer. The publication sets a twist angle in the range of 50° to 70° (column 2, line 4 of the publication) as an example of ultra-left twist. However, when a straight-edged end mill blade is installed at the cutting edge, there is no function to discharge the chips forward at that part, so the chips pushed forward from the extremely left-handed helical reamer body part are thrown into the end mill blade. Chips accumulate in the chip pocket and hit the cutting edge, significantly reducing the durability of the cutting edge. Also, since the end mill blade has a blade formed on its outer periphery, if the pilot hole is deviated to the side or tilted at the start of reaming,
Due to variations in cutting resistance on the inner circumference of the hole formed by the end mill blade during biting, a lateral force acts on the end mill blade, causing the end mill blade to shift to the side with less resistance, causing the reamer to tilt at the end mill blade. This causes the reamer to move forward, causing a tendency to follow the prepared hole, causing a bending moment to be applied to the reamer, which may cause it to break. Noise is also generated due to the swaying of the end mill blade.

In the latter (Utility Model No. 55-70922), the end mill blade was twisted to the left in order to increase the ability to discharge chips from the tip of the end mill blade. However, it is not possible to prevent lateral slippage and noise during biting.

(Purpose of the invention) This invention uses the action of a gun drill during drilling to give the reamer straightness even when the pilot hole is deviated laterally or inclined, and the reamer hole is accurately aligned on the initial center line. The purpose is to make it processable.

(Structure of the invention) In this invention, the rough edge of the cutting edge is formed by a drill twisted to the left, and next to the drill, a reamer with a super-twisted right-hand edge helix angle is provided with a slightly larger diameter than the drill. This reamer with a drill is characterized in that a biting part is provided and a second bevel part is provided in the biting part.

(Example) In Fig. 1, 1 is a blade part, 2 is a shaft part, 3 is a handle part, the rear end of the handle is provided with a mounting part 12 for applying rotational force, and O is the center. It is a line.
The blade part 1 includes a drill 4 (rough blade) at the tip and a reamer 5, and the reamer 5 forms a super-twisted right-hand edge helix angle, and has a biting part 5a at the tip. As clearly shown in Figure 1, the ultra-left-handed right-handed blade has a structure in which a right-handed blade is twisted to the left at a large angle with respect to the reamer center axis and can be cut clockwise. The drill 4 has a corner portion 6 at its tip. The edge of the blade, which is the biting corner 6, has a tip surface X perpendicular to the central axis, as shown in the upper right end of FIG.
4, and the axial Reiki α1 (the angle with respect to the plane passing through the central axis as seen in Figure 1) is, for example, as shown in the center of the left end of Figure 1. It is 6°. Depending on the material of the material to be cut, the angle may be 5° or in the range of 6 to 25°. The back of the outer peripheral edge X1 continuous with the biting corner 6 is a land X3 (a part of the cylindrical surface), and therefore there is no blade on the outer peripheral edge X1. The tip surface X4 behind the tip edge X2 continuous with the biting corner 6 is a surface perpendicular to the center line O, and therefore the tip edge X2 is also not a blade. A second beveled corner 7 is formed behind the beveled corner 6, and therefore only the beveled corner 6 serves as a blade. ), but Radial Reiki α2 (second
(Figure) has a positive rake angle of 8.5 degrees, and when combined, it essentially gives a positive rake angle and improves sharpness. By the way, the second bevel 7 is necessary to form the beveled corner 6 as a right-hand blade, and if the second bevel 7 is not present, there will be no clearance angle and the beveled corner 6 will be formed as a blade. Because you can't.

(Effects of the invention) According to the invention, it goes without saying that the reamer 5 has a very left-handed twist with a large twist angle and a right-hand blade, so that the chips produced by the reamer 5 can be smoothly sent to the front end. The fed chips can be sent forward more smoothly from the drill 4 portion at the tip. In other words, since negative axial reiki α1 is given to the biting corner 6 (because it is twisted to the left), the chips sent forward from the reamer 5 are positively absorbed by the twisted groove of the biting corner 6. This allows the cutting blade to be pushed forward, preventing chips from accumulating in the chip pocket, which improves the durability of the cutting edge. Also, since the land X3 is located behind the outer peripheral edge X1, a function similar to that of a gun drill pilot can be obtained. Therefore, when the reamer according to the present invention is rigidly chucked to a machine and machining is started, even if the pilot hole is deviated laterally or inclined from the center line of the reamer, the biting corner 6 Once the land X3 portion is fitted into the hole formed, the land X3 reliably prevents the drill 4 from shifting laterally and ensures the straightness of the drill 4. Therefore, even if the machining allowance of the prepared hole is uneven on the inner circumferential surface of the hole and a lateral force is applied to the drill 4 due to the difference in cutting resistance, even if the land Once fitted, the land X3 thereafter performs the pilot function of the gun drill, and reliably prevents not only the horizontal displacement of the drill 4 but also the noise caused by the horizontal shaking of the drill 4. Therefore, once the drill 4 hits the entrance of the pilot hole on its center line, there is no risk of it shifting laterally even if it receives a lateral force, and it moves straight while being guided by the land X3. Therefore, the center line of the obtained reamed hole precisely coincides with the center line of the reamer initially set in the machine, and no bending stress is applied to the reamer during processing, and the drill 4 does not cause horizontal vibration. , the pinging noise that occurs when using an end mill blade is also reliably prevented. Further, according to the present invention, there is no need to attach blades to the outer circumferential edge X1 and the tip edge X2 of the drill 4, making it easy to manufacture the reamer and reducing costs. Furthermore, if a positive radial rake α2 is provided as shown in FIG. 2, the rake angle becomes positive and the sharpness improves.

Furthermore, by forming the drill 4 having the corner portion 6 and the reamer 5 following it, reaming is performed after rough machining with the drill 4.
A beautiful hole surface can be formed without placing a large burden on the reamer 5.

[Brief explanation of the drawing]

Figure 1 is a front view, Figure 2 is a partial view of the tip, and Figure 3 is a front view.
The figure is a perspective view. 4...Drill, 5...Reamer.

Claims (1)

[Scope of utility model registration request] Form the rough edge of the cutting edge with a drill 4 twisted to the left,
Next to the drill 4 is a reamer 5 which is twisted more to the left than the torsion of the drill 4 and has a right-handed edge.
The drill 4 is provided with a slightly larger diameter, and the drill 4 is provided with a beveled corner 6, and the beveled corner 6 is provided with a second bevel 7 for a relief angle in order to form this as a blade. A reamer with a drill featuring the following.