JPH02190215A - Reamer - Google Patents

Abstract

PURPOSE:To effectively prevent vibration of a reamer and to increase the roundness of a hole by setting the number of cutting edges of a reamer to an even number, setting different central angles within a specified range of a difference therebetween, and disposing a cutting edge on the opposite side, with the axis of a cutting edge therebetween. CONSTITUTION:Cutting edges 11 of a reamer are disposed in such a manner that the angles between radial lines connecting the adjacent cutting edges and the axis 0 are 50 deg., 60 deg., and 70 deg. in order backward in the rotating direction, and another cutting edge 11 is provided on the opposite side at an angle of 180 deg., with the axis 0 of the cutting edge 11 therebetween. A designated bite angle is given to the forward end portion of the cutting edge 11. Further, the margin width of the outer peripheral margin connected to the cutting edge 11 is set to 0.1D-1.4mm when the diameter of the cutting edge 11 is let be D. The cutting edge portion of the cutting edge 11 within the range of 15mm-30mm extending from the forward end to the base end side has a back taper, and the diameter of the cutting edge portion on the base end side from the cutting edge portion where the back taper is provided is constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reamer that can improve the roundness of a machined hole.

[Prior Art] Generally, a reamer has a plurality of cutting edges on the outer periphery of an elongated reamer body, and is used for finishing a pilot hole previously drilled with a drill or the like. However, in reaming, vibration of the reamer tends to occur due to misalignment between the prepared hole and the reamer and low tool rigidity, and as a result, the machined hole becomes polygonal. In particular, in the case of reaming, the accuracy of the machined hole is required to be severe, and such errors in roundness are a problem that cannot be overlooked.

Therefore, reamers have been developed in which cutting edges are arranged at unequal intervals in the circumferential direction. In this reamer, the cutting edge is formed so that at least one of the central angles formed by the radial lines connecting the adjacent ones and the axis is different from the other central angles, and the cutting edge is formed so that at least one central angle between the radial lines connecting the adjacent ones and the axis is different from the other central angles. It has the advantage of being able to prevent vibration. Here, in the conventional unequal-split reamer, the difference in center angle between adjacent cutting edges is set to be relatively small, about 2° to 3°.

[Problems to be Solved by the Invention] However, even in the above-mentioned conventional unequal division type reamer, vibration of the reamer body could not be sufficiently prevented. That is, vibration in reaming occurs because the frequency of the impact force that the reamer body receives when the cutting blade bites into the workpiece matches the natural frequency of the reamer body. The unequal division type reamer generates a plurality of impact forces having different frequencies, thereby canceling out the vibrations transmitted to the reamer body. However, when the reamer body is long and thin, such as a gun reamer, a large bending moment acts on the reamer body, so the natural frequency of the reamer body is different from that under normal cutting conditions, and the vibration transmitted to the reamer body is canceled out. It becomes impossible to do so.

[Purpose of the Invention] This invention was made in view of the above circumstances, and can effectively prevent the occurrence of vibration even in machining in which a large bending moment is applied to the reamer body, and can prevent the polygonalization of the hole and improve the true shape of the reamer. The purpose is to provide a reamer that can increase circularity.

[Means for Solving the Problems] The reamer of the present invention has an even number of cutting edges, and
The difference between different central angles is lθ.

The main feature is that the cutting blades are arranged at 180° opposite sides with respect to the axis of the cutting blades.

[Operation] The above numerical limits are within a range that can effectively prevent the occurrence of vibration not only under normal cutting conditions but also during heavy cutting. That is, as a result of numerous experiments conducted by the present inventors, it has been confirmed that sufficient roundness can be obtained if the difference between the center angles of the cutting edges is 10° or more. However, the difference between the central angles is 2
If it exceeds 0°, the difference in the depth of cut of each cutting edge becomes large, and the circularity of the hole decreases. Furthermore, since the number of cutting blades is an even number and the cutting blades are located 180 degrees opposite to each other across the axis of one cutting blade, the reamer body is guided by the cutting blades, making the vibration of the reamer body even more effective. is prevented.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a side view showing the gun reamer of the embodiment. The reference numeral l in the figure is the reamer body. The reamer body 1 has a cylindrical shape that can be rotated around the axis 0, and a shank 2 with a larger diameter than the distal end is attached to the base end of the reamer body 1.
is formed. Furthermore, four grooves 3 extending in the axial direction are formed at equal intervals in the circumferential direction on the outer periphery of the central part in the axial direction of the reamer body l, and the grooves 3 are provided with guide pads 4.
is inserted. Note that the guide pad 4 is not necessarily necessary. Further, a hole 5 is formed in the center portion of the reamer body 1 along the axis 0, and a tapered hole 6 continuous to the hole 5 is formed in the tip portion. A tip (reamer body) 7 is brazed to the taper hole 6.

The tip 7 is made of cemented carbide, and six chip discharge grooves 8 are formed on its outer periphery. In addition, a hole 9 that is continuous with the hole 5 of the reamer body l is formed in the center portion of the chip 7 along the axis 0, and an oil hole lO that communicates with the hole 9 and the chip discharge groove 8 is formed. There is. A cutting edge 11 is formed on the outer peripheral ridgeline of the wall surface of the chip discharge groove 8 facing the rotation direction.

The cutting edges 11 have center angles formed by radial lines connecting adjacent ones and axis 0 that are sequentially 5 mm toward the rear in the rotational direction.
0°, 60°, 70°, and the axis of cutting edge II is 0.
Another cutting blade on the 180° opposite side! It is arranged so that I exists.

Moreover, a predetermined biting angle is attached to the tip of the cutting edge II. Furthermore, the margin width of the outer peripheral margin continuous to the cutting edge 11 is 0.1D to 0.1D when the diameter of the cutting edge 11 is D.
It is set to 1.4mm, and the conventional reamer's 0.03D to 0,
It is set wider than 04D. This enhances the burnishing effect of the margin and improves the surface roughness of the machined hole.

Also, the length of the cutting blade 11 is 15 m from the tip to the base end.
A back taper is provided on the cutting edge in the range of m to 30 mm, and the diameter of the cutting edge on the proximal side of the cutting edge provided with the back taper is constant. The above back taper is
0.01mm to 0 per 00mm in the axial direction
．． 0.06 mm, preferably 0.01 mm to 0.06 mm.
It is set to 02mm. Note that in the conventional reamer, a back taper is provided over the entire length of the cutting blade 11.

In the gun reamer configured in this way, the difference in the center angles of the cutting edges 2 is 10° to 20', which is much larger than that of the conventional unequal-split reamer, so the reamer body 1
It is possible to reliably cancel out the vibrations transmitted to the hole, thereby preventing the hole from becoming polygonal and increasing its roundness and dimensional accuracy.

Furthermore, since the above reamer has a back taper only on the tip side of the cutting blade 11, the clearance between the margin and the machined hole or guide bushing is small. Therefore, the vibration of the reamer can be further reliably prevented, and the vibration can be reliably canceled out, and the dimensional accuracy of the hole can be further improved. Furthermore, since the margin width is set wider than that of conventional reamers, the surface roughness of the machined hole can be improved due to its burnishing effect.

Next, FIGS. 4 and 5 show other embodiments of the present invention. The gun reamer shown in these figures differs from the previous embodiment in that the cutting blade is formed in multiple stages so that the diameter increases stepwise from the distal end to the proximal end, and the same components as the gun reamer are used. are given the same reference numerals. This gun reamer is provided with cutting blades 1'2a, 12b, and 12c sequentially from the distal end to the proximal end.

Here, the intermediate cutting edge 12b has a length Q h415 mm or less, and this cutting edge 12b has a length of 0.01 mm to 0.06 m per 100 mm in the axial direction over its entire length.
A back taper of 0.01 mm to 0.02 mm is provided. In addition, the cutting blade 12a and the cutting blade 1
2c has a coating of 0.01 mm to 0.0 (imm, preferably 0.0 mm, preferably 0.0 mm, within a length a from the tip to the proximal end)
A back taper of 0.01 mm to 0.02 mm is provided.

Note that this gun reamer also has cutting edges 12a... made of cemented carbide, but as shown in FIG. 6, the cutting edges 12a... may be configured.

This gun reamer is used for finishing the parts shown in Fig. 7, and the cutting blade 12a cuts the part of the part shown by a, the cutting blade 12b cuts the part shown by b-h, and the cutting blade 12c cuts the part shown by b-h. 1. The part indicated by j is to be cut.

With this gun reamer, it goes without saying that the same effects as in the above embodiment can be obtained, and in particular, each cutting edge 12a...
Since the back taper is provided with a length equal to
2a can be easily re-polished.

FIG. 8 is a diagram showing the results of machining with the gun reamer, and as can be seen from the results, the roundness of the hole was 2μ or less, which was a high degree of accuracy.

Furthermore, the surface roughness of the hole in this process is 0.26Z~0
．． 482, and the inner wall surface of the hole was extremely smooth.

[Effects of the Invention] As explained above, in the reamer of the present invention, the number of cutting blades is an even number, the difference between mutually different center angles is 10 @ ~ 20°, and ! 80
°Since the cutting blade is placed on the opposite side, the vibration transmitted to the reamer body can be reliably offset, which has the effect of preventing the hole from becoming polygonal and increasing its roundness. It will be done.

[Brief explanation of the drawing]

1 to 3 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a view of the tip of the gun reamer in the axial direction, FIG. 2 is a partially fragmented side view thereof, and FIG. Figure III-III
Line sectional views, FIGS. 4 and 5 show other embodiments of the present invention, FIG. 4 is a partially fragmented side view of the gun reamer, FIG. The figures are a side view showing a modified example of the gun reamer shown in Fig. 4, Fig. 7 is a side sectional view showing the workpiece, and Fig. 8 is a diagram showing the roundness of the machined hole. l...Reamer body, 8...Chip discharge groove, ! 1... Cutting blade, 12a, 12b, 1 0... Axis line. C... Cutting blade,

Claims (4)

[Claims] (1) A plurality of chip discharge grooves are formed on the outer periphery of the reamer body that is rotated around the axis, and cutting edges are formed on the outer peripheral ridgeline of the wall surface facing the rotation direction of the chip discharge groove, and the cutting blades and the axis that are adjacent to each other are formed. In a reamer in which the cutting blades are arranged so that at least one of the central angles formed by the radius lines connecting 10° to 20°, and the cutting blades are arranged 180° opposite to each other across the axis of the cutting blade. (2) When the diameter of the cutting edge is D, the margin width of the outer peripheral margin continuous to the cutting edge is set to 0.1D to 1.4 mm. Reamer. (3) 15mm to 30mm from the tip of the cutting blade to the base end side
Within the range of 0.01 mm per 100 mm in the axial direction
Claim 1 or claim 1, characterized in that a back taper of 0.06 mm is provided, and the diameter of the cutting blade portion on the proximal end side of the cutting blade portion provided with the back taper is constant. The reamer described in Section 2. (4) The cutting blade is provided in multiple stages so that the diameter increases stepwise from the distal end to the proximal end,
The length of the shortest cutting blade among the multiple cutting blades is 15m.
m or less, and 0 per 100 mm in the axial direction on this cutting edge.
．． A back taper of 0.01 mm to 0.06 mm is provided, and a back taper of 0.01 mm to 0.0 mm is provided for every 100 mm in the axial direction from the tip of the other cutting blade to the proximal end within the length range of the shortest cutting blade.
．． Claim 1 or 2, characterized in that a back taper of 0.06 mm is provided, and the diameter of the cutting blade portion on the proximal end side of the cutting blade portion where the back taper is provided is constant. The reamer described in.