JPS6128447B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reamer that is used when processing an already drilled pilot hole with high precision, particularly a reamer that is most suitable for use as a blind hole. This was done in an effort to obtain something that had good accuracy and was easy to manufacture.

The cutting edge of a conventional reamer was as shown in FIG.

That is, figures A to C in the same figure show a single blade, and a land L is provided as a guide at the cutting edge Z, the position where this has been rotated by 180 degrees, and one other place. This shows a two-blade design, with cutting blades Z provided at positions rotated by 180 degrees, and a land L serving as a guide between each cutting blade Z.

In the same figure, the three-blade type has an equilateral triangle with the cutting edge Z rotated 120 degrees, and in the same figure, it has a square blade.
It has four blades with cutting edge Z located at a position rotated 90 degrees.

Ch to nu in the same figure schematically show the positions of special cutting edges Z in the case of multiple blades,
In the same figure, R indicates an even number of blades, and N in the same figure shows an unequal angle.

However, with the above-mentioned conventional reamer, the runout of the cutting edge and land of the reamer can be reduced to almost zero, and the rotational accuracy (runout) for driving the reamer or the rotational accuracy (runout) for driving the workpiece can be processed with almost zero. However, it is impossible to achieve a roundness accuracy of less than 2μ, and this was considered to be the limit of roundness accuracy.

This is because all the conventional reamers mentioned above have a cutting edge Z.
Is there another cutting edge Z or land L at the position rotated by 180 degrees (Fig. 1 I to E, G, R, N), or is there a cutting edge Z and the land L closest to the position rotated by 180 degrees? It is an isosceles triangle that includes a triangle formed by line segments connecting two cutting edges Z or lands L (FIG. F and C).
It turned out to be from.

In other words, if there is another cutting edge Z at the 180° rotation position of the cutting edge Z as shown in Fig. 1D, and it does not touch the pilot hole at any other point, the reamer core should be aligned in the direction perpendicular to the line connecting the cutting edges Z. moves, and the machined hole tends to be a distorted circle with equal diameter and not a perfect circle.

In addition, the case where there is another cutting edge Z or land L at the 180° rotational position of the cutting edge Z and also has a point of contact with the pilot hole will be explained based on FIGS. 2 and 3, as shown in FIG. Then (in the same figure, point A is the cutting edge Z
, and points B and C indicate the positions of other cutting edges Z or lands L, respectively), in Fig. 2,
The closest point to the point rotated 180 degrees around center O from point A, that is, the other point of point C, that is, from point B to center O
A perpendicular line drawn from the above point B to the line segment connecting center O and point C (or its extension line, the same applies below). The smaller the value of the length ratio/ is 1, the better the circle-forming effect is.

This means that the closest point to the point A rotated 180 degrees around center O, that is, point C, determines the diameter dimension, and point B (points other than points A and C) determines the circle-forming action. It can be understood from examples and experience that if points B and C are set in the right direction (clockwise direction) in the figure, the roundness will be good, and if they are set in the opposite direction, the rigidity will be high (dimensional accuracy in the diametrical direction). It can be understood from examples and experience that the circle-forming effect is higher), so the value of / above is the circle-forming effect of the above item replaced with a coefficient, and the smaller this value is, the better the circle-forming effect is. It is.

However, in this case, as shown in Fig. 3, the point A rotated 180 degrees around the center O coincides with the point C, so for any point B, the points E and D coincide, /=1 always, the circle-forming effect disappears, and the circle is never perfect.

In other words, in the case of the two-blade reamer shown in Figure 1D, the reamer core moves in the direction perpendicular to the line connecting points A and C as described above, and the machined hole tends to be a distorted circle with equal diameter, making it impossible to make a perfect circle. Must not be. Also, if /=1, point A is 180
Point C is located at the rotated position, and the rigidity (dimensional accuracy in the diametrical direction) is maximum. Therefore, the rigidity is too large and the circle-forming effect is eliminated, causing the core of the reamer to run out, similar to the case with the two-blade reamer mentioned above. This is because it is easy to become

In addition, as shown in Figure 1 F and C, the triangle formed by the line segment connecting the cutting edge Z and the two cutting edges Z or land L closest to the position rotated by 180 degrees is an isosceles triangle that includes an equilateral triangle. The case is explained based on Fig. 4 (points A, B, and C in the figure
is the same as above), the closest point to the point rotated by 180 degrees around point A, that is, point C, is
This is the point that performs the action of determining the diameter in reaming, and the other point, namely B, is the point that performs the circle-forming action. However, in this case, as shown by the two-dot chain line, △
Since AB′C′ is an isosceles triangle (including an equilateral triangle), point B′ and point C′ are both points that perform the above two actions, and perform the action of determining the diameter and the point used for the circle-forming action. There will be two points each, so it will not be a perfect circle. This means that the reference point with the same stiffness is point A.
This is because there will be two points, B', points A and C', and the circle-forming action will be eliminated, causing the reamer core to run out and not resulting in a perfect circle.
In this case, cases and experience tend to result in an even number of polygons.

The present invention is based on the above theory, and this invention is based on the fifth theory.
A detailed explanation will be given based on the embodiments shown below. In the figure, 1 is a reamer according to the present invention, which is a so-called solid reamer type in which a shank 3 is integrally connected to the rear of a blade part 2. It is used by attaching it to a boat, etc.

4 is a land for the cutting blade, and 5 and 6 are lands for the first and second guides, respectively.The lands 4, 5, and 6 are arranged on the same circumference, that is, the solid cylindrical material is arranged in the longitudinal direction. It is formed by cutting out a straight line.

The reason why there are three lands 4, 5, and 6 in this way is to eliminate unnecessary cutting edges and guides since a circle is determined by three points, and to have one cutting edge and two guides. The width S of the lands 4, 5, and 6 is set to about S=(20-25)/360πd, where d is the diameter of the above-mentioned circle, so that stable reaming can be performed.

That is, if the width S of the land is set to 0 (S=0), it will not serve as a guide and will cause digging and pilling. Furthermore, even if the width S of the land is too large, the structural effect of the dividing angle of each land is lost, so the angular range of the cutting edge and the land is set within 270°.

A cutting edge 7 is formed at the tip of the cutting edge land 4, and is composed of a rake face 8, a side flank face 9, and a front flank face 10, and the biting angle α is set to about 30°.

The rake face 8 has a flat groove shape, and in order to discharge cutting chips backward, its rake angle in the radial direction θ ₁
is negative, including 0, and the rake angle in the axial direction θ ₂
are set exactly including 0. That is, by setting the rake angle θ ₁ in the radial direction to a negative value including 0, the cutting chips are directed outward from the center along the cutting edge 7, and the rake angle θ ₂ in the axial direction is set to a positive value including 0. By causing the cutting waste to flow backward from the cutting blade 7, the generated cutting waste is discharged backward from the shaft along the inner wall of the machined hole.

Of course, these rake angles θ ₁ and θ ₂ can be changed as appropriate depending on the material of the workpiece, etc.

11 and 12 are the first and second guides, respectively;
A first guide angle β 1 (α=β 1 ) having the same angle as the above-mentioned biting angle α, and a first guide angle β 1 (α=β 1 ) which is the same angle as the above-mentioned biting angle α, and a first guide angle β _{1 (α=β 1 ) which is the same angle as the above-mentioned biting angle α, and a first guide angle β 1} (α=β _{1 ) which is the same angle as the above-mentioned biting angle α, are cut out in two steps on the outer circumferential surfaces of the tips of the guide lands 5 and 6} , respectively. A second guide angle β ₂ is formed, and a step t 1 is provided between the front end face and the tip of the cutting blade 7, and a step t ₁ is provided between the above-mentioned biting angle α and the first guide angle β ₁ . A spacing t ₂ is formed between the reamer 1
The rotation of the hole and the cutting by the cutting blade 7 at this time are not hindered, and the bottom surface of the prepared hole can also be machined to the vicinity of the center.

The reason for forming the step t ₁ and the interval t ₂ in this way is that the cutting edge 7 cannot cut unless it precedes the guides 11 and 12, and the ridgeline near the center of the cutting edge 7 is oriented in the axial direction. Since the cutting direction is perpendicular to the cutting direction, it is possible to cut to the center of the pilot hole with relatively little resistance.

The dividing angle (center angle) ψ 1 between the cutting edge 7 and the first guide ₁₁ located in the counter-rotation direction is 120° (ψ ₁ = 120°), and both guides 11, 12 The dividing angle ψ ₂ between is 90° (ψ ₂ =
90°), but this is because the cutting edge 7
The guides 11 and 12 are not provided at the 180° rotated position, and the triangle formed by the line segments connecting the cutting blade 7 and the guides 11 and 12, respectively, is made not to be an isosceles triangle including an equilateral triangle. This is to eliminate the drawbacks of the reamer 1, and furthermore, the direction of the resultant force R of the cutting resistance generated during cutting by the reamer 1 is a direction that intersects the line segment connecting both guides 11 and 12,
This is because it can fulfill its role as a guide.

This will be explained based on FIG. 12 and below (in this figure, point A indicates the position of the cutting blade 7, points B and C indicate the positions of the guides 11 and 12, respectively, and FIGS. 2 to 4 ), ∠BOC=90° (=ψ
₂ ), point D coincides with center O, /
(=radius), and the length is the maximum, and the value of / is the minimum, and the length is sufficient to make the direction of the resultant force R of cutting resistance during cutting intersect with the line segment. be.

The resultant force R of this cutting resistance is the resultant force of the principal component force R ₁ generated in the downward direction in the figure and the back force R ₂ generated in the left direction in the figure, as shown in FIG. Since the rake angle θ ₁ in the radial direction is set to a negative value including 0, the back force R ₂ generated when the cutting blade 7 is pushed during cutting becomes larger than when the rake angle θ ₁ is set to a positive value. The direction will be as shown in the figure. Although the direction of this resultant force R cannot be determined as it depends on various conditions, it is believed to be between 90° and 180° clockwise from the cutting edge 7, and in a direction away from 180°.

That is, if ∠BOC<90°, the length will be shortened, and the value of / will not only become large, but also the length will be shortened, and if ∠BOC>90°, the length will be shortened, and This is because if the length is too long, the resultant force R of the cutting resistance acts on the guides 11 and 12 in a way that bites into them, and this biting causes the roundness accuracy to deteriorate.

Therefore, it is considered that approximately ∠BOC=90°±5° (=ψ ₂ ) is optimal.

In addition, the reason for setting ∠AOB=120° (=ψ) is that it is preferable to make it larger than this in order to reduce the above value, but as shown in Fig. 13, the resultant force R of the line segment and the above cutting resistance The intersection with Furthermore, if ∠AOB<120°, not only will the value of ∠ become large, but the guide 12 will be positioned at a position where point A has been rotated by 180°.

Therefore, it is considered that approximately 115°<∠AOB(=ψ)<125° is optimal.

Therefore, ∠BOC=90° (=ψ ₂ ), ∠AOB=125
(= ψ ₁ ), even if the central angle of the width of the land of the guide 11 is set to 25 degrees as shown in FIG. 25)/360πd, this can be expressed as a central angle of 20° to 25°.When considering the circle-forming action by taking into account the width of the land, it is important to consider the large angle at which the effect of the circle-forming action disappears, i.e. 25° is the limit. Therefore, in Fig. 14, 25° clockwise from points A, B, and C is the central angle of each land width), γ
₂ = 35°, γ ₁ = 30°, and γ ₂ - γ ₁ = 5°, which is a sufficient angle that does not form an isosceles triangle, and γ ₁ - central angle of land width = 30° - twenty five
゜=5゜, the width of the land including point A and point C
In the positional relationship of the width of the land including point A, even if the width of the land including point A is rotated by 180 degrees, it will deviate from the width of the land including point C by 5 degrees (γ ₁ - centroid angle of the land width). Even a part of it will not polymerize. Moreover, the above /=√3/2<
It can be set to 1.

In this way, in the combination of ∠AOB, ∠BOC, and the central angle of the land width, each angle is adjusted within an allowable range so that γ ₂ >γ ₁ and γ ₁ >the central angle of the land width.

The material of the reamer 1 according to the present invention is as follows:
In addition to commonly used tool steels, high-speed steels, etc.
By using M type carbide and further ion plating, it can be adapted to machining difficult-to-cut materials such as nickel-based heat-resistant alloys.

The method of using the present invention is to attach it to a floating reamer and rotate it in the same way as a normal reamer, inject an appropriate cutting oil, cut the inner surface of the prepared hole, and use it as a machined hole. That's what I do.

Since the present invention has the above configuration, it has the following effects.

Regardless of the rotational accuracy of the reamer and workpiece mounting shaft, it is possible to obtain a machined hole with a roundness accuracy that exceeds the accuracy inherent to the reamer. Circularity accuracy can be obtained.

Not only is there less variation in the machined holes and less expansion margins, but the machined surface roughness is also good, and the cylindricity and straightness accuracy are also good.

Chips are discharged backwards, so there is no clogging of chips, and the groove length is short, so the rigidity is high, and the relatively simple shape makes it easy to manufacture.

It is possible to machine the prepared hole up to the vicinity of the center of the bottom surface, and it is also possible to machine the through hole.

[Brief explanation of the drawing]

Figures 1 to 4 show the cutting edges of different conventional reamers; Explanatory drawings showing defects, FIGS. 5 to 14 show an embodiment of the present invention, FIG. 5 is a front view, and FIG. 6 is a front view.
The figure is a side view, Fig. 7 is a bottom view, Fig. 8 is an enlarged sectional view taken along the line - - of Fig. 6, and Figs.
11 is a perspective view showing the cutting edge portion, and FIGS. 12 to 14 are explanatory diagrams showing the operation. 1... Reamer, 4, 5, 6... Land, 7...
Cutting edge, 8... Rake face, 9, 10... Relief face, 1
1, 12...Guide, ψ ₁ , ψ ₂ ...Dividing angle,
θ ₁ , θ ₂ ... rake angle.

Claims (1)

[Claims] 1. One cutting edge and first and second guides are provided, and the lands of the cutting edge and both guides are formed on the same circumference, and the positions of the two guides are set such that the center of the cutting edge is the same as the center of the cutting edge. Shift it from the extension line of the connecting line, set the triangle formed by the line segments connecting the cutting edge and both guides to a position where it does not become an isosceles triangle including an equilateral triangle, and further set the rake angle of the rake face to a negative value including 0 in the radial direction. , is set to be positive including 0 in the axial direction, and the direction of the resultant force of the cutting resistance is a direction that intersects the line segment connecting the two guides. 2. It has one cutting edge and first and second guides, and the lands of the cutting edge and both guides are formed on the same circumference, and the rake angle of the rake face is negative including 0 in the radial direction and negative in the axial direction. For a reamer with a positive setting including 0, the dividing angle between the cutting edge and the first guide located in the counter-rotational direction of this is approximately 115
From ゜ to 125゜, the dividing angle between the guides is about 90゜±5
A reamer characterized by being set at ゜. 3. When the diameter is d, the width S of each land is approximately S=(20-25)/360πd.
Reamer as described in section.