JP2845888B2 - Rounding method of bending part in bending hole - Google Patents

Description

The present invention relates to a method of rounding a bent portion of a bent hole,
Suitable for machining with a machining center or NC drilling machine.

<Conventional technology> When a fluid passage is formed in an element member in a hydraulic device or the like, cutting using a drill or the like is generally used. However, since this fluid passage is often bent due to design necessity, Processing of the bent portion has been a problem.

FIGS. 7 and 8 show the plane of the aluminum block 02 in which the bending hole 01 having the bending angle of 90 ° is formed, and A in FIG.
The design required shape of each of the -A cross sections is shown. As shown in these figures, it is desired in design that the bent portion 03 of the bent hole 01 be formed smoothly so as not to cause a pressure loss when a fluid flows.

However, in processing using only a drill, it was only possible to make the shape as shown in FIG. 9 in order to secure a sufficient passage area. In the case of forming the shape as shown in FIG. 8, a method of applying electric discharge machining or manual work to the bent portion 03 after the drilling, or joining the divided portions by welding is adopted. .

<Problems to be Solved by the Invention> However, in order to obtain the shape shown in FIG. 8 by electric discharge machining, the shape of the machining tool (discharge electrode) becomes complicated and the number of necessary electrodes increases, and the machining cost and the number of man-hours for manufacturing the tool are increased. And so on. Further, in the case of an aluminum-based material, there is also a defect that both the surface roughness and the shape become defective in electric discharge machining.

On the other hand, manual work is performed with a hand grinder or the like, but it is difficult to finish the shape accurately, and since there is an individual difference in the skill of the worker, a uniform product cannot be manufactured.

And, in the method by welding, when the fluid flowing through the fluid passage is at a high pressure, it is necessary to perform groove welding on the entire periphery of the joint, which requires a large number of processing steps and costs, and also requires welding equipment. .

An object of the present invention is to solve the problems of the conventional processing method described above.

<Means for Solving the Problems> Accordingly, the present invention relates to a method of rounding a bent portion in a bent hole formed in a material, wherein the cutter having a spherical cutting edge having substantially the same diameter as the bent hole is bent. Insert into the hole,
While the shank is kept parallel to the straight portion of the bent hole, the spherical cutting edge is rotated and moved in an arc shape in the bent portion while cutting is performed, and the arc-shaped movement locus of the spherical cutting edge is performed. The present invention proposes a method for rounding a bent portion in a bent hole, characterized in that the cutting range is sequentially changed by moving the cutting line along the bisector of the bending angle.

<Operation> While maintaining the shank parallel to the straight part of the bending hole,
While the cutting process is performed while rotating the spherical cutting edge in an arc shape at the bending portion, the arc-shaped movement trajectory moves along the bisector of the bending angle to perform smooth and accurate rounding. .

<Embodiment> An embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows an enlarged cross section of a bent portion showing a rounding method according to the present embodiment, and FIG. 2 shows a cross section taken along the line BB of FIG. FIG. 3 to FIG. 6 are cross-sectional views showing a procedure of forming a bent hole in this embodiment.

FIG. 3 shows a pilot hole processing as a first step of forming a bent hole, and two pilot holes 3 and 4 are drilled from the upper side and the lateral side of the aluminum block 1 by the drill 2. On this occasion,
Machining is stopped at a position where the blade tip 2a of the drill 2 coincides with the center lines 4a, 3a of the prepared holes 4, 3 orthogonal to each other. In addition, all the processing in this embodiment including the preparation of the prepared hole is performed by a single machining center (not shown).

Next, as shown in FIG. 4, a ball end mill 5 having substantially the same diameter as the pilot hole is inserted through one pilot hole (the upper pilot hole 3 in the present embodiment), and the second step of forming a bent hole is performed. Do. This is for removing the excess portion 7 on the outer peripheral side of the connecting portion of the pilot holes 3 and 4, that is, the bent portion 6.

When the second step is completed, as shown in FIG. 5, a cutter 10 having a spherical cutting edge 8 having substantially the same diameter as the prepared hole 3 formed at the tip of the shank 9 is inserted into the prepared hole 3, and the third step of the present invention is performed. Is started. Hereinafter, FIG. 1 and FIG.
The processing procedure will be described with reference to the drawings.

First, an arc formed on the inner peripheral side of the bent portion 6 shown in FIG.
The radius R of 11 is obtained. The radius R of the arc 11 is preferably as large as possible in consideration of the flow resistance of the fluid, but the size is naturally determined by the shape of the tool and the like. DC and DS
Are the diameters of the spherical cutting edge 8 and the shank 9, respectively, and CL, θ
Are defined as the minimum allowable gap and the bending angle between the shank 9 and the pilot hole, respectively, the following equation is obtained.

Therefore, for example, DC = 16, DS = 8.2, CL = 0.3, θ = 90
If ゜, R ≦ 4.29. Then, the radius of the movement locus R ₁ of spherical cutting edges 8 when forming the arc 11 becomes R + DC / 2.

Next, feed in the outer peripheral direction is given along the bisector 12 of the bending angle θ, and cutting is performed again in an arc shape. The movement trajectory R _{2 at} that time
The radius of the feed is x, Becomes That is, the movement locus of the spherical cutting edge 8 is always
Is set so as to be in contact with the center line 3a. Needless to say, these arithmetic controls are performed by a control device (not shown) which is a control unit of the machining center.

Thereafter, rounding is performed by sequentially feeding n times to R ₃ , R ₄ ,..., R _n . The number n of times of feeding can be set arbitrarily, and is determined in consideration of finishing accuracy and man-hours. For example,
While the portion indicated by broken lines in FIG. 2 is a excess thickness 13 to be removed in the third step, which part is removed N殆in R _1, satisfactory performance without giving R ₂ and subsequent feeding If so, that is fine.

When the rounding from the upper pilot hole 3 is completed, the aluminum block 1 is rotated as shown in FIG. 6, and the cutter 10 is inserted from the lateral pilot hole 4 to perform the same rounding.

As described above, in this embodiment, since a single machining center performs the processing from the preparation of the prepared hole to the rounding of the bent portion, a highly accurate bent hole can be formed in a short time and at low cost.

The present invention is not limited to this embodiment. For example, an NC drilling machine or the like may be used instead of the machining center, or the number of tool changes by using the cutter 10 instead of the ball end mill 5 in the second step. May be reduced. In this embodiment, the bending angle is 90.
Although the case of と し た is taken as an example, the bending angle in the present invention is not limited to this, and in the case of an obtuse angle, rounding from only one prepared hole may be possible.

<Effects of the Invention> According to the present invention, while the shank is maintained parallel to the straight portion of the bent hole, the cutting process is performed while rotating the spherical cutting edge while moving in an arc shape at the bent portion, and the circle is formed. Since the arc-shaped movement trajectory moves along the bisector of the bending angle, when applied to a machining center, an NC drilling machine, etc., a highly accurate bent hole can be machined in a short time and at low cost.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a bent portion showing one embodiment of a rounding method according to the present invention, and FIG. 2 is a sectional view taken along line BB in FIG. FIGS. 3 to 6 are cross-sectional views showing a procedure for processing a bent hole in this embodiment. 7 and 8 are a plan view showing a design required shape of an aluminum block having a bent hole and a sectional view taken along line AA in FIG. 7, respectively. FIG. 9 shows an example of a conventional processed shape. It is sectional drawing. In the figure, 1 is an aluminum block, 2 is a drill, 3 and 4 are prepared holes, 5 is a ball end mill, 6 is a bent portion, 8 is a spherical cutting edge, 10 is a cutter, and 12 is a bisector of a bending angle. .

Claims (1)

(57) [Claims] 1. A method for rounding a bent portion in a bent hole formed in a material, wherein a cutter having a spherical cutting edge having substantially the same diameter as the bent hole is inserted into the bent hole, and the shank is bent. While maintaining parallel to the straight portion of the hole, while performing the cutting process by rotating the spherical cutting edge in an arc shape at the bending portion while rotating, the arc-shaped movement trajectory of the spherical cutting edge is determined by the bending angle. A method for rounding a bent portion in a bent hole, wherein a cutting range is sequentially changed by moving the cutting range along a bisector.