JPS6347016A - Reamer - Google Patents

Abstract

PURPOSE:To increase the roughness of a finished surface by setting the twisting angle of at least a portion committing the current machining of at least one of the cutting edges to an angle value which is different from the twisting angle of the corresponding portions of the other cutting edges. CONSTITUTION:Those three 12, 14, 16 of the six cutting edges 12-17 which are situated on every other ridges shall have a twisting angles theta1 in their portion from the tip till a point 26 to set off a length L to the tail side of the bite-in part 24. The twisting angle of the corresponding portions of the other cutting edges 13, 15, 17 shall be theta2 which is greater than theta1. The inter-edge distance at the tail of the portions 26 committing the current machining of the cutting edges 12-17 shall be equal, and the twisting angle of the cutting edges 12-17 situated nearer the tail than said portions 26 shall all be the equal angle theta. This eliminates generation of resonance during processing with reamer body to lead to prevention of tool marks forming, and thus the roughness of the finished surface can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reamer that has a plurality of cutting edges formed on the outer periphery of a reamer body and is used for finishing a hole.

[Prior Art] Figures 4(A) and 6(B) to 6 show conventional reamers of this type, each having a cylindrical shape, a reamer body l,
A plurality of cutting edges 3 . here,
As shown in Fig. 6, each cutting edge 3..., 4...
They are spaced apart circumferentially at equal intervals and are formed in a spiral shape with the same twist angle θ. At the tips of these cutting edges 3, 4, . In addition, a straight shank 7 is attached to the proximal end of one reamer body 1.
A tapered shank 8 is formed at the proximal end portion of the other reamer body 2.

In these reamers, the cutting blades 3..., 4...
Cut the inner wall of the hole by cutting the inner wall of the hole with the length L parts 9, 10 from the rear end of the chamfered part 5.6 toward the parallel part, and cut these parts 9, 10. ...Improve the roughness of the finished surface of this hole in the parallel part on the rear end side.

[Problems to be Solved by the Invention] However, in the conventional reamers described in 1., micro vibrations occur in the reamer body under certain cutting conditions such as a certain number of revolutions, and as a result, the workpiece material is particularly austenitic. When using difficult-to-cut materials such as stainless steel copper and titanium alloys, or aluminum alloys,
As shown in C), the cutting surface has the same number of cutting edges and a spiral shape with a helix angle approximately equal to the helix angle θ of these cutting edges, and has a depth of about 0.005 mm to 0.05 mm. There is a problem that groove-shaped four parts (tool marks) M... are formed.

Therefore, the inventor of this application conducted intensive research to find out the cause of the occurrence of the above-mentioned microvibrations, and as a result, he came to the conclusion that the cause lies in the following points.

That is, in the conventional reamer described above, when the portions 9 and IO of each cutting blade 3.4 involved in cutting bite into the inner wall of the workpiece, the reamer main body I , 2 are subjected to a relatively large cutting force. In the above-mentioned reamers, the helix angles of the respective cutting edges 3.4 are equal to each other and are formed at equal intervals in the circumferential direction.
As shown in the figure, from each part of the cutting blade 3.4 to the adjacent cutting blade 3.
The intervals up to 4 in the circumferential direction are equal. Therefore, in the reamer body l, 2, each cutting edge 3.4 is
A large cutting load from the part 9.10 involved in cutting acts intermittently at a constant cycle.

On the other hand, these reamers generate resonance at a relatively low frequency because their length is larger in relation to their outer diameter than other tools such as face mills and end mills. For this reason, when a large cutting load is applied to the reamer body 1.2 at regular intervals under certain cutting conditions such as margin width and rotation speed, the reamer body 1.2 generates resonance.
As a result, it has been estimated that microvibrations are generated to the extent that they adversely affect the surface roughness, such as the formation of tool marks M.

``Object of the Invention'' This invention was made based on the above estimation, and can prevent resonance vibration caused by cutting loads from occurring in the reamer body, thereby improving the finished surface roughness. The purpose of this invention is to provide a reamer that can improve the

[Means for Solving the Problems] In order to achieve the object set forth in ``-'', the present invention provides a helix angle of at least one cutting edge of a plurality of cutting edges, and of at least a portion thereof involved in cutting. is set at a different angle from the helix angle of the relevant part of the other cutting blades.

[Function] In the lamer having the configuration described in 2, the distance in the circumferential direction between the part of the cutting blade set at different helix angles involved in cutting and the relevant part of the adjacent cutting blade is the same as that of the cutting blade. It changes continuously from the tip of the blade toward the rear end. Therefore, the period of vibration acting on the reamer body becomes irregular and varies along the axial direction, and these vibrations cancel each other out, so that resonance due to the cutting load does not occur in the reamer body. Therefore, it is possible to prevent resonance vibrations from occurring in the reamer body, which would worsen the surface roughness and cause tool marks to be formed on the finished surface.

[Example] An example of the present invention will be described below with reference to FIGS. 1(A) and 1(B).
) and FIG. 2.

In the figure, reference numeral II indicates a cylindrical reamer body, and the outer periphery of the tip of this reamer body 11 has six twisted cutting edges 12, 13, 14. ．． 15,16°17 are formed. Further, the tips of these cutting blades 12 to 17 are formed into chamfered portions 24 having a chamfer angle β, and chip discharge grooves 18, 19, 20.2 are provided between these cutting blades 12 to 17.
+, 22.23 are formed. Further, a straight yank 25 is formed at the base end portion of the reamer body 11.

Here, as shown in FIG.
A total of 3 cutting blades located every other row out of 17 + 2.1
4.16, the helix angle from the tip of the cutting blade to the portion 26 involved in long cutting on the rear end side of the chamfered portion 24 is θ.
1, and the other three cutting edges 1 located between these.
3.15.17, the helix angle from the tip of the cutting blade to the portion 26 involved in the cutting is θ, respectively. These 01 and 02 are set to θ and <θ, respectively.

Further, these six cutting blades 12 to I7 are set so that the intervals between the cutting blades, that is, the widths of the chip discharge grooves 18 to 23 are equal at the rear end of each portion 26 involved in cutting. . The helix angles of these cutting edges 12 to 17 located on the rear end side of this portion 26 are all set to the same angle θ.

However, in the reamer with the above configuration, the three cutting edges 1
2.14.16 Part 26 involved in cutting from the tip of the cutting blade
The helix angle θ1 up to the other three cutting edges 13, 15.1
Since the helix angle θ in this part of 7 is made smaller, the cutting edges 12 and 13 in this part are made smaller as shown in FIG.
, the circumferential spacing between the cutting edges 14 and 15 and the cutting edges 16 and 17 gradually narrows from the tip to the rear end, while the cutting edges I3 and 14 and the cutting edges 15 and 16
And the circumferential distance between the cutting edges I7 and 12 gradually increases.

As a result, from the cutting blades 12 to 17 to the reamer body 11.
The period of vibration due to the cutting load acting on the shaft changes irregularly along the axial direction, and these vibrations cancel each other out in the axial direction. As a result, resonance due to the cutting load does not occur in the reamer body 11, and therefore, resonance that would form a tool mark on the cut surface of the reamer body II and worsen its surface roughness is generated. This can be reliably prevented from occurring. As a result, it is possible to improve the finish surface roughness of the machined hole.

By the way, this resonance prevention effect becomes more effective as the rate of change in the interval between the cutting edges 12 to 17 increases, so if the difference between the helix angles θ1 and θ is increased, the problem becomes worse.

However, on the other hand, if the helix angles 01 and θ are made to have different sizes over the entire length of the cutting edges 12 to 17, these cutting edges will change as the spacing between the cutting edges 12 to 17 changes. The chip discharge grooves 18 to 23 between the blades 12 to 17 vary in width. Specifically, in FIG. 2, the width of the chip evacuation grooves +8, 20, and 22 gradually narrows from the tip side to the rear end side, while the width of the chip evacuation grooves 19, 21.2
The width of 3 gradually becomes wider. Here, the chip discharge groove 19.21
With respect to ゜23, there is no problem because the width gradually increases, but with respect to chip discharge i18.20.22, if the width on the rear end side becomes too narrow, it becomes difficult to discharge chips.

However, in this reamer, the torsion angle O and θ are changed only between the tip of each of the cutting blades 12 to 17 and the portion 26 involved in cutting, and this portion 26
At the rear end, the gap between each cutting edge, that is, the chip evacuation groove 1
Since the widths of 8 to 23 are set to be equal,
Chip discharge grooves 18 to 2 in parallel parts of cutting blades 12 to I7
3 is the same width up to the base end of the reamer body 11. Therefore, the occurrence of chip clogging as described above can be prevented.

In addition, in the reamer of the embodiment described in "2," six cutting edges 12 to 17 are formed, but the invention is not limited to this.
Any material having a plurality of cutting edges may be used. Further, the helix angles of three of the six cutting edges 12 to 17 are made the same, and the helix angles are alternately large and small, but the helix angles of all the cutting edges may be different from each other, or they may be different from each other. Cutting edges having different helix angles may be sequentially formed in the circumferential direction from the smallest helix angle. In any case, in the present invention, the helix angle of at least one of the plurality of cutting edges may be set to be different from the helix angle of the other cutting edges.

Also, regarding the twist direction of the cutting edge, it can be applied in the same way to either the left or right twist angle, and furthermore, it can be applied to at least one cutting edge among the plurality of cutting edges with a helix angle of 0 (straight edge). A helix angle may be added. Furthermore, the yank portion may also have a tapered shank 30 as shown in FIG.

[Effects of the Invention] As explained below, according to the gluer of the present invention, the helix angle of at least one of the plurality of cutting edges, and at least the portion involved in cutting, can be adjusted to Since the helix angle is set to be different from the helix angle of the relevant part of other cutting blades, the circumferential distance between the cutting blade part with a different helix angle and the adjacent cutting blade part is from one end of the cutting blade. The vibration changes continuously toward the other end, and as a result, the vibrations acting on the reamer body become irregular and vary along the axial direction.

Therefore, resonance vibrations do not occur in the reamer body, and it is therefore possible to prevent resonance vibrations from forming on the finished surface of the reamer body and worsening the surface roughness. Therefore, it is possible to improve the finished surface roughness of the machined hole.

[Brief explanation of the drawing]

FIGS. 1(A) and 1(B) show an embodiment of the reamer of the present invention, where FIG. 1(A) is a side view and FIG. 1(B) is a side view.
2 is a developed view of the blade portion of the reamer shown in FIG. 1, FIG. 3 is a side view showing another embodiment of the present invention, FIG. 4 (A) and FIG. 5(A) is a side view showing a conventional glue machine, and FIG. 4(B) and FIG. 5(B) are taken along line IV-IV in FIG. 4(A) and FIG. 5(A), respectively. The cross-sectional view along the line and the cross-sectional view along the ■-■ line in Figure 6 are the developed views of the blade portion of these conventional reamers (Figures 7 (A), (B), and (C).
) indicates the shape of the hole machined using the conventional glue machine mentioned above.
The same figure (A) is a front view, the same figure (B) is the same figure (A) ■-■
The cross-sectional view taken along the line (C) is a cross-sectional view taken along the line ■--■ of the same figure (B). 11...Reamer body, ■2-I7...Cutting blade, 12a=17a...Part involved in cutting of cutting blade,
24...Eclipse (=J part, β...Eclipse angle, θ1.θ2...Twisted angle.

Claims (1)

[Claims] In a reamer in which a plurality of cutting edges are formed on the outer periphery of the reamer body and extending along the axial direction, the torsion angle of at least one of the plurality of cutting edges, and at least a portion involved in cutting, is determined. , a reamer characterized in that the helix angle is set at a different angle from the helix angle in the relevant part of other cutting blades.