JPS61152307A - Drilling by twist drill - Google Patents

Abstract

PURPOSE:To improve the working accuracy of a regular inclined hole by previously cutting a taking-out portion uneven part by a ball end mill and drilling the inclined hole by a twist drill. CONSTITUTION:Vertically to the worked edge surface (a) of a workpiece, a taking-up portion uneven part 4 is removed along the outer peripheral side surface (e) of an inclined hole 1 in the part ranging from the (c) point to the (d) point on the outer edge surface of a regular hole diameter by a ball end mill 3 having the nearly equal radius R to the hole diameter of the inclined hole 1. Then, the regular inclined hole is worded with high precision by the drilling in the axial direction of the inclined hole 1 by a twist drill 2. In this case, the edge surface (a) is held at an angle of 90 deg. with respect to the axis center of the ball end mill 3.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for drilling oblique holes using a drill.

Conventional technology As shown in FIG.
The center line of the oblique hole (when drilling C with a drill, as shown in Figure 2, the center line of the oblique hole) that is not perpendicular to the plane and has inclination angles α and β. Because the end surface (&) is inclined at an angle of inclination (α) with respect to the vertical line, the uneven machining allowance in the radial direction () occurs, and a cutting reaction force is generated in the radial direction. It was very difficult to drill a diagonal hole in the correct position and a hole with the correct size because the drill could not be drilled in the correct position and the drill would oscillate. Furthermore, the smaller the diameter of the hole and the larger the angle of inclination, the more pronounced the effect, and it was almost impossible to drill a diagonal hole of regular size.

In addition, as shown in Fig. 3, when the oblique hole penetrates through the hole and is inclined by the angle of inclination φ) with respect to the bottom machined end surface ('b), the unevenness of the machining allowance (→ There was a risk that the cutting reaction force would occur in the radial direction, causing the tip of the drill to escape or lateral deflection, resulting in the hole being bent.

Conventionally, as a means of solving this problem, it was necessary to remove the uneven portion (b) of the machining allowance in advance using an end mill or the like. As shown in Fig. 6, an end mill (support) with almost the same size as the hole diameter of the oblique hole (1) is installed perpendicularly to the machined end surface (&) between points <a) and (d) of the hole diameter. Move in the direction of the arrow along the oblique hole wall circumferential surface (e) and remove the uneven machining amount (in the uneven part) in the shape of a circular vertebra.

Problems to be Solved by the Invention When the uneven machining area is removed in a conventional end mill, as shown in FIG. Since it is difficult to match and a deviation of (1) inevitably occurs, the tip of the drill inevitably deviates from the center (0) of the circular vertebrae and drills the hole, as shown in Figure g.
As shown in Figure 1, there were problems such as the diagonal hole being deviated by (1) from the normal position, or the diagonal hole being drilled at an angle of (@), or the regular diagonal hole not being drilled.

Means for Solving the Problems The present invention has been devised to solve the above-mentioned problems, and eliminates uneven machining areas by replacing the end mill with a ball end mill. This is to obtain a diagonal hole.

As shown in Fig. 1, a ball end mill ■ with a radius (R) that is approximately the same as the hole diameter (R) is made by drilling an oblique hole perpendicularly to the machined end surface (a) of the workpiece, and the outer end surface point of the normal hole diameter is (
From point C1 to point (d) along the outer circumferential wall surface (e) of the oblique hole, remove the uneven machining allowance. Therefore, the shape after deletion is a spherical surface, and as shown in Figure 5, even if the R center of the spherical surface and the center line of the oblique hole, that is, the axis of the drill do not match and are shifted by (1), it will bite in the correct position. This makes it possible to drill to the regular dimensions and obtain a regular diagonal hole.

Embodiment An embodiment of the present invention will be explained with reference to a method of drilling a sub-injection hole (1) in a chamber for an internal combustion engine shown in FIG.

The sub-injection hole (hole diameter lφ, inclination angle ato degrees with respect to the machined end faces (al and (b), β≠j degrees) affects engine performance and requires strict processing accuracy.

As shown in Figure ≠, the workpiece is gripped with the precision of a 2-diameter ball end mill (3) so that the machined end surface (a) is perpendicular, and the workpiece is gripped by a slidable workpiece fixing device. The outer end face point of the diagonal hole (from point 01 to (dJ point)
i! The uneven machining allowance portion is deleted without moving it along the wall surface (e). In this example, the rotation speed of the ball end mill is 2j
OO''', feed speed of workpiece 301!l m/I!1
I went to 1111.

Next, as shown in Fig. 5, the workpiece is held in a workpiece fixing device that holds the workpiece at an angle so that the axis of the 2ψ drill Q and the center line of the sub-injection hole V) are on the same straight line. A regular sub-injection hole was obtained by drilling the holes.

Effect: When drilling an oblique hole that has a certain inclination angle with respect to the machined end face, by removing the uneven machining allowance part in advance with the zare end mill according to the present invention, it is possible to prevent the workpiece from being cut in the radial direction of the drill due to uneven machining allowance. This eliminates force, prevents lateral vibration, and eliminates the uneven machining area, which becomes the biting surface of the drill, resulting in a spherical shape, which allows the drill to bite into the diagonal hole at the correct position. The holes were drilled to the correct dimensions, improving machining accuracy and significantly improving quality.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a chamber according to an embodiment of the present invention. FIGS. 2 and 3 are explanatory diagrams of uneven machining allowances when drilling oblique holes. Figure ≠ is an explanatory diagram of the removal of uneven machining allowance portions by the ball end mill of the present invention. FIG. 5 is an explanatory diagram of drilling according to the present invention. FIG. 6 is an explanatory diagram of the removal of uneven machining allowance parts using a conventional end mill. FIGS. 7 to 7 are explanatory diagrams of drilling with a conventional end mill. /: Oblique hole 2 Nitrile 3: Ball end mill
IA: Uneven installation part T: End mill patent applicant Riken Co., Ltd. 10 Fang 6 Diagram O 6 Diagram Fang A

Claims (1)

[Claims] A drilling method characterized in that, when forming an oblique hole in a workpiece using a drill, uneven portions of machining allowance are removed in advance using a ball end mill to form the oblique hole in the workpiece.