JPS6140433Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention relates to a reamer used for finishing holes.

BACKGROUND ART As is well known, a reamer has a plurality of parallel blades left behind from the blade grooves on its outer periphery, and the inner wall surface of the hole is cut by the inclined cutting edge formed at the tip of the blade. Moreover, a kind of burnishing is performed by the outer diameter margin continuous with this inclined part. Generally, the outer diameters of the respective blade portions are all the same diameter, and during processing, the cutting edges at the tips of the respective blade portions perform cutting at the same time. However, such a reamer has the disadvantage that, when precise finishing is to be performed, finishing must be performed again.

In order to solve this problem, as shown in FIG. 3, there is a method in which two stages of outer diameter portions 11 and 12 are formed in the axial direction to perform two stages of machining. In this case, cutting edges 13 and 14 are formed at the tip end of each blade part 11 and 12, but when these cutting edges 13 and 14 are worn out, re-sharpening is necessary between the two blade parts 11 and 12. It is limited to the length range of the outer diameter margin portion 15, so there is little margin for repolishing, and on the other hand, if the margin portion 15 is lengthened in an attempt to increase the margin for repolishing, the wasted time increases accordingly. There is.

Fig. 4 shows another example in which both rough finishing and finishing are performed at the same time in one machining process, in which each of the plurality of cutting parts formed on the outer periphery has a small outer diameter part. It is divided into a blade part 16 and a blade part 17 having a large outer diameter part, and an inclined cutting edge 18 at the tip of the large diameter blade part 17 and an inclined cutting edge 19 at the tip of the small diameter blade part 16.
(There is a similar device described in, for example, Japanese Utility Model Application Publication No. 100419/1983.) Problems that the invention aims to solve: The device shown in Figure 4 above. In this case, when the cutting edge 19 at the tip of the small diameter blade part 16 is reground, the cutting edge 18 of the large diameter blade part 17 can also be reground at the same time, so the margin for regrinding is provided in the margin part 20 between the two cutting edges 18 and 19. The benefits are not limited. However, when the cutting edge 19 at the tip of the small-diameter blade section cuts, the cutting edge 18 at the tip of the large-diameter blade section 17 does not cut.
However, there is a drawback that cutting cannot always be performed stably.

In addition, when performing two-stage cutting in this way, the biting angle α at the finishing cutting edge 18 is 1 to 1.
It is desirable to have a small angle close to a flat angle of about 5 degrees, but as shown by the two-dot chain line in the figure, if you try to make the angle small like this, both cutting edges 1
This has the drawback that the margin portion 20 between 8 and 19 becomes longer, and wasted time is more likely to occur.

This invention was made with the aim of eliminating the drawbacks of the conventional two-stage reamer.

Means for Solving the Problems In order to achieve the above object, this invention provides a reamer having a plurality of blade parts 1a and 1b on its outer periphery, and a reamer having the same chamfer angle at the tip of each of these blade parts. The boring cutting edges 4a and 4b are formed on the same surface, and the large diameter cutting edge 1b has a cutting edge of the boring cutting edge 4b at the rear end of the boring cutting edge 4b in the direction of the reamer center line. The finishing cutting edge 6 is formed with a biting angle smaller than the chamfering angle, and the tip Q of the finishing cutting edge 6 formed at the rear end of the boring cutting edge 4b in the reamer center line direction forms the small diameter cutting edge 1a. It is characterized by being located closer to the center than the outer diameter part of the.

Embodiment Hereinafter, the configuration of this invention will be explained based on the illustrated embodiment. In FIGS. 1 and 2, 1
a, 1b are six blade parts formed between the blade grooves 2, 2... in the axial direction, and these blade parts 1a, 1b
... has a small outer diameter D ₁ and a large outer diameter D ₂
Different types of blade portions 1a and 1b are formed, and these blade portions 1a and 1b having different diameters are arranged alternately. However, the small diameter blade portions 1a and the large diameter blade portions 1b are not necessarily arranged alternately. In addition, the difference in the outer diameter of the blade parts 1a and 1b in this case is _D2 - _D1 =0.05~
It is 0.2mm. Each blade part 1 formed in this way
A, 1b, . Therefore, the front end corners of these inclined portions 3a and 3b in the rotational direction are
The cutting edges 4a and 4b are respectively for boring, and both the cutting edges 4a and 4b have the same biting angle α and are arranged on the same plane in both the large-diameter blade portion 1b and the small-diameter blade portion 1a. ing. Note that the biting angle α in this case is, for example, approximately 45°.

Next, in the large-diameter blade portion 1b, a finishing slope portion 5 having an angle β is formed continuously from the tip slope portion 3b, and its front end corner in the rotation direction is the cutting edge 6.
It is becoming. Therefore, this finishing cutting edge 6
has a biting angle β smaller than the boring cutting edge 4b, and the finishing cutting edge 6 is the boundary between the finishing cutting edge 6 and the boring cutting edge 4b.
The tip Q is located at a position closer to the center by δd than the outer diameter portion of the small diameter blade portion 1a. In this case, δd is small, for example, about 0.02 to 0.05 mm. Further, the biting angle β of the finishing cutting edge 6 is set to be as small as about 1° to 5°.

As mentioned above, the tip Q of the finishing cutting edge 6 formed at the rear end of the boring cutting edge 4b is in the small diameter cutting edge 1a.
Because it is located closer to the center than the outer diameter of
Between the boring cutting edge 4b and the finishing cutting edge 6, a first margin portion 7 for performing a burnishing action is left on the outer diameter portion of the small diameter cutting edge portion 1a. Further, the outer diameter portion of the large diameter blade portion 1b following the rear end portion of the finishing cutting edge 6 also serves as the second margin portion 8. These margin parts 7 and 8 are usually not provided with cutting edges. Furthermore, a negative clearance angle may be formed in the outer diameter portion of the small diameter blade portion 1a, the diameter becoming smaller from the rear side toward the front side in the rotation direction, thereby preventing runout and maintaining the true position. The roundness can be improved.

Therefore, when machining is performed using the reamer formed as described above, first, the boring cutting edges 4a and 4b at the tips of the small-diameter blade portion 1a and the large-diameter blade portion 1b simultaneously cut the inner wall of the hole to the inner diameter _D1. −δd, and then the boring cutting edge 4a at the tip of the small diameter blade portion 1a is δ
d alone, and then the first margin part 7
After burnishing by
The finishing cutting edge 6 cuts to the inner diameter _D2 , and then burnishing is performed by the margin section 8 on the outer periphery of the large-diameter cutting section 1b to achieve a more precise finish.

Effects of the invention According to this invention, unlike the conventional example shown in Fig. 4, the boring cutting edges formed at the tips of both the small-diameter blade part and the large-diameter blade part perform cutting at the same time, resulting in stable machining. It has the effect of being able to do the following. Furthermore, in this design, another finishing cutting edge is formed after the cutting edge at the tip of the large-diameter cutting edge, and as mentioned above, this finishing cutting edge has a margin at the outer diameter of the small-diameter cutting edge. The chamfer angle can be made as small as 1° to 5° without increasing the length, and therefore, the finishing accuracy is also much better compared to the one shown in Fig. 4 above. Become. In addition, in the present invention, the rough finishing in the first stage is performed by the boring cutting edges of both the large-diameter and small-diameter parts, and the finishing in the second stage is performed by the finishing cutting edges of the large-diameter part. Since the chisel is used for boring and finishing, the number of cutting edges is different between boring and finishing, which results in a kind of unjust splitting effect or unequal pitching effect, which is well known in the past.
The effect of improving finishing accuracy can be obtained. It goes without saying that in the present invention, regrinding can be performed regardless of the length of the margin between both cutting edges.

[Brief explanation of drawings]

FIG. 1 is an end view showing the tip of a reamer according to the present invention;
Fig. 2 is a side view of the blade portion when it is expanded, and Figs. 3 and 4 are side views of the blade portion of a conventional reamer. 1a . . . Small diameter blade portion, 1b . . . Large diameter blade portion, 4a,
4b...boring cutting edge, 6...finishing cutting edge.

Claims (1)

[Scope of utility model registration request] In a reamer that has a plurality of blades on its outer periphery, a boring cutting edge with the same chamfer angle is formed on the same surface at the tip of each of these blades, and furthermore, the large diameter blade has a boring cutting edge formed on the same surface. A finishing cutting edge is formed at the rear end of the boring cutting edge in the reamer centerline direction with a chamfer angle smaller than that of the boring cutting edge, and a finishing cutting edge is formed at the rear end of the boring cutting edge in the reamer centerline direction. A reamer characterized in that the tip Q is located closer to the center than the outer diameter part of the small diameter blade part.