JPH0333367Y2 - - Google Patents

Description

[Detailed description of the invention] - Industrial application field - This invention relates to a boring cutter used for drilling, and relates to an improvement of a boring cutter in which two cutter blades are attached to the tip of the shaft. It is something.

-Prior Art- A boring cutter having two cutter blades attached to the tip of a shaft is well known, and there are two types of drilling operations performed using this type of cutter. One of them is called a balance cut, and as shown in FIG.
In this embodiment, one of the holes 2a is used to cut the inner diameter side of the bottom surface of the hole 30, and the other 2b is used to cut the outer diameter side and the inner peripheral surface of the bottom surface.

The other method, as shown in FIG.
This is intended to improve processing efficiency by simultaneously processing the bottom and inner circumferential surfaces of the hole 30 using holes a and 2b. In this specification, this latter mode of processing will be referred to as simultaneous cutting.

Generally, in this type of boring cutter,
Two cutter blades 2, 2a, and 2b are slidably attached to the shaft 1 in the radial direction, so that the structure can accommodate changes in the diameter of the hole 30. That is, for example, as shown in FIG.
7, the cutter blade 2 is moved forward and backward in the radial direction by moving the screw forward and backward, and the cutter blade 2 is clamped and fixed by the blade fixing screw 11 shown in FIG. ing.

-Problems that the invention attempts to solve- However, with this type of conventional boring cutter,
Since the position of the cutter blade 2 in the shaft axis direction cannot be adjusted, the following problems arose. The first problem is that when simultaneous cutting is performed, the cutting loads on the two cutting blades 3a, 3b become uneven due to relative positional errors in the axial direction of the two cutter blades 2a, 2b. For example, in simultaneous cutting, 2
If the two cutting blades 3a, 3b have an axial error of 1/2 or more of the machining feed, actual cutting will be performed with only one cutting blade. Since the machining feed given to the shaft 1 is approximately 0.1 mm during finishing machining, efficient and highly accurate machining will be difficult unless the error in the axial direction of the two cutting edges 3a and 3b is approximately 1/100 mm or less. Become. With conventional boring cutters, it has been difficult to match the axial positions of the cutting edges with high precision.

The second problem is that at least one of the cutter blade 2 and cutting edge 3 must be replaced when performing a balance cut and when performing a simultaneous cut. That is, during balance cutting, both cutting edges 3a and 3b must have an axial step Δa equal to or more than 1/2 of the machining feed, while during simultaneous cutting, both cutting edges must be in the same position with high precision. Therefore, in order to achieve both, either the cutting blade 3 must be replaced (in the case of a throw-away tip) or the cutter blade 2 itself must be replaced, which is a hassle.

-Means for solving the problem- This invention solves the above problem by making the position of the cutter blade 2 adjustable not only in the radial direction of the shaft 1 but also in the axial direction.

That is, in the boring cutter of this invention, the two cutter blades 2, 2a, 2b are inserted into the radial through hole 4 provided at the tip of the shaft 1 at its base 22.
A blade fixing screw 11 screwed into the shaft 1 perpendicularly to the through hole 4 and a shaft 1 attached to each cutter blade 2 serve as means for fixing the cutter blade and advancing and retracting means.
A radial adjustment screw 25 is provided which is screwed toward the radial direction.

Then, a horizontal hole 12 is bored in the base side of the shaft 1 adjacent to the through hole 4, and an axial hole 13 communicating with the tip of the horizontal hole is opened facing the back side of the cutter blade 2 installed. The pressing members 16, 16a are loosely fitted into the directional hole 13, and the axial adjustment screw 15 is screwed into the horizontal hole 12.
6a is pushed by the axial adjustment screw 15 through the tapered surfaces 14, 31 of the intermediate member 32 inserted into the axial adjustment screw 15 itself or the tip thereof.

-Function- In the boring cutter with the above configuration, the cutter blade 2 is
The cutter blade 2 is moved in the radial direction by threading the radial adjustment screw 25 screwed into the cutter blade 2 to adjust the radial position of the cutting edge 3.

Then, by further screwing the axial adjustment screw 15, the pressing members 16, 16a are pushed toward the back surface of the cutter blade 2 by the action of the tapered surfaces 14, 31, and the pressing members 16, 16a push the cutter blade. By pressing 2 in the shaft axial direction, the axial position of the cutting blade 3 can be adjusted.

This radial and axial position adjustment is performed while measuring with a dial gauge or the like, and after setting both cutter blades 2 to desired positions, the cutter blades 2 are fixed by tightening the blade fixing screws 11.

-Example- The figure shows an example of this invention. In the figure, 1 is a shaft serving as the base of the boring cutter, 4 is a through hole with a square cross section drilled at the tip of the shaft, and 5 is a shaft. Each cutter blade mounting portion 5 is continuous with a receiving surface 7 that is continuous with a radial wall surface 6 of the through hole 4 and a back surface 8 of the through hole 4. It has a stepped surface 9. On shaft 1,
A screw hole 10 opening in the radial wall surface 6 of the through hole 4 is provided in a direction perpendicular to the through hole 4, and a blade fixing screw 11 is screwed into the screw hole 10.

Two horizontal holes 12 are provided on the base side of the shaft 1 adjacent to the through hole 4, parallel to the through hole 4 and offset symmetrically from the center of the shaft 1, and the tips of the horizontal holes 12 are A short axial hole 13 extends to a position just before penetrating the shaft 1 and extends perpendicularly from the tip thereof, and opens in the stepped surface 9 of the cutter blade mounting portion. This horizontal hole 12 is a screw hole, and the axial adjustment screw 1 has a conical surface 14 at the tip.
5 is screwed into the axial hole 13, and a steel ball 16 is inserted into the axial hole 13. The length of the steel ball 16 is greater than the length of the axial hole 13, and therefore the steel ball 16 protrudes from the tip of the lateral hole 12.

The two cutter blades 2, 2a, and 2b attached to the shaft 1 are L-shaped, and have a cutting blade mounting portion 21 having a thickness approximately equal to the radial width D of the through hole 4 and a thickness 1/1/2 of the radial width D of the through hole 4. 2, and the cutting blade 3 is fixed to the tip of the cutting blade mounting part 21. The base 22 is inserted into the through hole 4 from both sides with the surface 23 on the side where the cutting edge 3 is provided facing each other. The base portion 22 is slightly thicker on the cutting blade attachment portion 21 side, and has a thickness t thinner than 1/2 of the radial width D of the through hole 4 by the amount of play.
Further, the width w of the base portion 22 is narrower than the axial width E of the through hole 4 by the amount of play.

The cutting blade attachment part 21 of the cutter blade has a base 2.
A screw hole 24 parallel to the extending direction of the screw hole 2 passes through the screw hole 24, and a radial adjustment screw 25 is screwed into the screw hole 24.

The base 22 of the cutter blade inserted into the through hole 4 of the shaft 1 from both sides is clamped and fixed from both sides by blade fixing screws 11 screwed into the shaft 1. At this time, the base 2 of both cutter blades
2, the parts of the cutting blade mounting part 21 side having the wall thickness t are pressed against each other, and the back surface of the cutting blade mounting part 21 is pressed and fixed to the receiving surface 7 of the cutter blade mounting part.

When the radial direction adjustment screw 25 of each cutter blade is screwed in with the blade fixing screw 11 lightly tightened, the tip of the screw is pressed against the tip 17 of the shaft from the side, and the cutter blade 2 is pushed into the shaft. advance in the radial direction. Further, when the axial adjustment screw 15 is screwed, the conical surface 14 at the tip pushes the steel ball 16 toward the through hole 4, and the steel ball 16 is pushed against the back surface of the cutter blade 2 on the cutting edge side. be touched. Due to this pressing of the steel ball 16, the base 22 of the cutter blade becomes oblique within the through hole 4 within the axial play, thereby causing the cutting blade 3 to move forward. This advance amount is about 0.2 mm, and if the cutting feed is within 0.4 mm, it is sufficient to adjust the axial position of the cutting blade 3 during balance cutting and simultaneous cutting.

In the first embodiment, the steel ball 16 is used as the pressing member and is directly pressed by the conical surface 14 of the axial adjustment screw 15, but as shown in FIG. A short cylindrical member 16a having a flat tapered surface 16b at the base end is used to form the horizontal hole 1.
It is also possible to adopt a structure in which an intermediate member 32 having a tapered surface 31 in surface contact with the tapered surface 16b is loosely fitted to the distal end of the intermediate member 2, and the intermediate member is pushed by the axial adjustment screw 15. According to the structure shown in FIG. 9, the support rigidity in the axial direction of the cutter blade 2 can be increased, so that the boring cutter can withstand a larger cutting load and can perform processing with higher precision. can be obtained.

-Effects of the invention- According to the boring cutter of this invention described above, the two cutting blades attached to the tip of the shaft can be positioned in the axial direction of the shaft, so that the front cutting blades can be aligned accurately. It is also possible to create a desired level difference, thus avoiding the adverse effects caused by positional errors of the cutting blades during simultaneous cutting, and also allowing one of the cutting blades to be advanced or retracted without replacing the cutting blade or the cutter blade. This makes it possible to accommodate both balanced cutting and synchronous cutting. In addition, if you adjust the position by moving the cutting blade back and forth while measuring with a dial gauge, you can adjust the position of the cutting blade by 1/2.
It can be set with an accuracy of 10 mm or less, providing sufficient accuracy as a boring cutter, and has a simple structure and sufficient rigidity to withstand heavy cutting.

[Brief explanation of the drawing]

Figures 1 to 6 are views showing a first embodiment of this invention, in which Figure 1 is a partially cutaway plan view of the shaft, Figure 2 is a side view, and Figure 3 is an exploded perspective view. , Fig. 4 is a sectional view of section A in Fig. 2, and Fig. 5 is a sectional view of section A in Fig. 2.
FIG. 6 is a cross-sectional view of section B in the figure, and FIG. 6 is a cross-sectional view of section C in FIG. FIG. 7 is an explanatory diagram of balance cutting, and FIG. 8 is an explanatory diagram of simultaneous cutting. FIG. 9 is an enlarged sectional view of a main part showing a second embodiment of this invention. In the figure, 1: shaft, 2, 2a, 2b: cutter blade, 3, 3a, 3b: cutting blade, 4: through hole,
8: Back side of through hole, 11: Blade fixing screw, 1
2: Horizontal hole, 13: Axial hole, 14: Conical surface, 1
5: Axial adjustment screw, 16: Steel ball, 16a: Short cylindrical member, 17: Shaft tip, 22: Blade base, 25: Radial adjustment screw, 31: Tapered surface, 32: Intermediate member.

Claims (1)

[Scope of utility model registration request] A boring cutter equipped with two cutter blades 2 at the tip of a shaft 1, a blade fixing means 11 for pressing the cutter blades against each other in a direction perpendicular to the surface thereof, and a blade advance/retreat means 25 for pushing the cutter blades in a radial direction. 2 is its base 22
are installed by being overlapped and inserted into a radial through hole 4 provided at the tip of the shaft, and a lateral hole 12 is provided at the base side of the shaft 1 of the through hole 4, and the tip of the lateral hole is connected to an axial hole 13. The through hole 4 opens on the back side 8 side facing the base 22 of each cutter blade, and the axial hole 13 has a pressing member 16,
16a is loosely fitted into the tapered surface 14,
A boring cutter characterized in that it is pushed in the shaft axial direction via a shaft 31.