JPS6128448B2 - - 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, and in particular, a reamer that is most suitable for use as a through 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. Each case is shown.

However, with the above-mentioned conventional reamer, it is assumed that machining can be performed with the runout of the reamer's cutting edge and land almost zero, and the rotational accuracy (runout) for driving the reamer or the rotational accuracy (runout) for driving the workpiece. However, it is impossible to achieve a roundness accuracy of within 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° (Fig. 1 I to H, G, R, N), or is there a cutting edge Z and the land L closest to the position rotated by 180°? It was found that this is because the triangle formed by the line segments connecting the two cutting edges Z or lands L is an isosceles triangle including an equilateral triangle (F and H in the same figure).

In other words, if there is another cutting edge Z at the 180° rotation position of the cutting edge Z as shown in Fig. 1 D, and it does not touch the pilot hole at any other point, the reamer core should be aligned perpendicularly 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 contact point with the prepared 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
, point B and point C are other cutting edge Z or land L.
), in Figure 2, connect the center O and point A from the point closest to the point rotated 180 degrees from point A, that is, from another point of point C, that is, B. Line segment (or its extension; the same applies hereinafter)
A perpendicular line drawn from the above point B to the center O and point C
The smaller the value of the ratio of the length of the perpendicular line drawn to the line segment connecting (or its extension, the same applies hereinafter) is less than 1, the better the circle-forming effect is.

This is because the point closest to point A rotated 180 degrees around center O, that is, point C, has the effect of determining the diameter dimension, and point B (points other than points A and C) has the effect of forming a circle. It can be understood from examples and experience that points B and C are set in the right direction (clockwise direction) in the same figure, resulting in good roundness, and setting them in the opposite direction increases rigidity (diameter dimension). Since it can be understood from examples and experience that the accuracy is higher), 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. That's why.

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 it is not a perfect circle.

In other words, in the case of the two-blade reamer shown in Figure 1 D, the core of the reamer 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 less true. It is not a yen. Also, if /=1, point A
Point C is located at the position rotated by 180°, where 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 lands L closest to the position rotated by 180 degrees is an isosceles triangle that includes an equilateral triangle. The case will be explained based on Figure 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, ie, point B, is the point that performs the circle-forming action. However, in this case, as shown by the two-dot chain line, △AB'C' is an isosceles triangle (including an equilateral triangle), so both point B' and point C' are the points that perform the above two actions, and the circle is formed. There are two points that perform the action and two points that perform the action that determines the diameter, so it is not a perfect circle. This means that there are two standards with the same rigidity, such as points A and B' and points A and C', and the circle-forming effect is eliminated, causing the reamer core to run out and not being a perfect circle. This is because it cannot.
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, and is a floating reamer. 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. These 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=(15-20)/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 0 (S=0), it will not serve as a guide and will cause digging and burrs. Furthermore, if the width S of the land is too large, the circle-forming effect due to the dividing angle of each land is lost, so the angular range of the cutting edge and the land is set within 180°.

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 forward, its rake angle in the radial direction θ ₁
is exactly the rake angle θ ₂ in the axial direction including 0.
are set to negative values including 0. That is, by setting the rake angle θ ₁ in the radial direction to a positive value including 0, cutting chips are moved from the outside of the cutting edge 7 toward the center, and the rake angle θ ₂ in the axial direction is set to a negative value including 0. By setting these, the cutting waste is caused to flow forward of the shaft from the cutting blade 7, and the generated cutting waste is discharged toward the center of the machined hole and forward of the shaft.

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 second guide angle slightly smaller than the above-mentioned biting angle α are formed by cutting the outer circumferential surfaces of the tips of the guide lands 5 and 6 into two stages. The front end surface is formed into _a conical surface with a sharp point at the center, and a distance t is provided between the biting part of the cutting blade 7 and the tips of the guides 11 and 12, respectively. Reamer 1
The rotation of the blade 7 and the cutting by the cutting blade 7 at this time are configured so as not to be hindered.

The reason for forming the interval t in this manner is that the cutting blade 7 must precede the guides 11 and 12 to perform cutting.

Then, the division angle (center angle) φ ₁ between the cutting edge 7 and the first guide 11 located in the counter-rotation direction is 60° (φ ₁ = 60°), and both guides 1
The dividing angle φ ₂ between 1 and 12 is 90° (φ 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 not an isosceles triangle including an equilateral triangle. This is to eliminate the drawbacks that the reamer 1 has, 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 to allow them to fulfill their role as a guide.

To explain this based on Fig. 12 et seq.
(In the same figure, point A is the position of cutting edge 7, point B
and point C indicate the positions of guides 11 and 12, respectively, and points A, B and C shown in FIGS. 2 to 4
), ∠BOC=90° (=
φ ₂ ), then the point D coincides with the center O, and =
(=radius) and the length becomes maximum,
Not only does the above value of / become the minimum, but the length is sufficient to make the direction of the resultant force R of cutting resistance during cutting intersect with the line segment.

The resultant force R of this cutting resistance is the resultant force of the main 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 positive value including 0, the cutting edge 7 has a biting tendency during cutting, so the back force R ₂ generated at this time makes the rake angle θ ₁ negative. It becomes smaller than when it is set, and the direction is as shown in the figure. The direction of this resultant force R depends on various conditions and cannot be determined, but
Slightly between 90° and 180° clockwise from cutting edge 7.
It seems to be in the direction of 90 degrees.

In other words, 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 ∠B′OC>90°, the length will be shortened. Furthermore, 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 the occurrence of this biting deteriorates the roundness accuracy.

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

In addition, the reason for setting ∠AOB=60° (=φ ₁ ) is that it is preferable to make it larger than this in order to reduce the above value, but it not only poses a problem in terms of rigidity, but also as shown in Fig. 13. As shown, the intersection of the line segment and the resultant force R of the cutting resistance is gradually shifted,
Cutting becomes unstable and rigidity decreases. Furthermore∠
If AOB < 60°, not only will the value of
This is because 2 would end up being located.

Therefore, it is considered that approximately 45°<∠AOB (=φ ₁ )<65° is optimal.

Therefore, by setting ∠BOC=90° (=φ ₂ ) and ∠AOB=60° (=φ ₁ ), even if the central angle of the width of the land of the guide 11 is set to 20° as shown in FIG. As mentioned above, when the width S of each land is set as S=(15~20)/360πd, this can be translated into a central angle of 15°~20°. When considering the action, we will explain the limit at a large angle at which the effect of the circle-forming action disappears, that is, 20°.Therefore, in Fig. 14, 20° clockwise from points A, B, and C is the center of each land width. ), the total (90° + 60° + 20°) is 170°, γ = 10°, and there is a distance of 10 between the position where the land containing point A is rotated 180° and the position of the land containing point C. It is possible to have a margin of ゜, and the above /=
It is possible to set √3/2<1.

In this way, in the combination of ∠AOB, ∠BOC, and the center angle of the land width, the tension is set within the permissible range of each angle that satisfies 0°<γ<25°.

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 the reamer to a floating chuck and rotate it in the same way as a normal reamer, and cut the inner surface of the prepared hole while injecting an appropriate cutting fluid. That is to say.

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 well-machined hole with a roundness accuracy that exceeds the accuracy inherent to the reamer. Accuracy can be obtained. Not only is there less variation in the machined hole and there are fewer expansion margins, but the machined surface roughness is also good.
Furthermore, cylindricity and straightness accuracy are also improved.

Not only are chips discharged forward and there is no chip clogging, but the groove length is short so the rigidity is high, and the relatively simple shape makes it easy to manufacture.

[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, Figure 7 is a bottom view, Figure 8 is an enlarged sectional view taken along the - line in Figure 6, and Figures 9 and 10 are
11 is a perspective view showing the cutting edge portion, and FIGS. 12 to 17 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, _φ1 , _φ2 ...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. The position is shifted from the extension line of the connecting line, and the triangle formed by the line segments connecting the cutting edge and both guides is not an isosceles triangle including an equilateral triangle, and the rake angle of the rake face is adjusted to be exactly including 0 in the radial direction. , is set to a negative value 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 is equipped with 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 set to exactly including 0 in the radial direction and in the axial direction. In a reamer set to a negative value including 0, the dividing angle between the cutting blade and the first guide located in the counter-rotational direction is approximately 45° to 65°, and the dividing angle between the guides is approximately 90°±. A reamer characterized by being set at 5°. 3. When the diameter is d, the width S of each land is approximately S=(15-20)/360πd.
Reamer as described in section.