JP2000176714A - Hole processing method - Google Patents

Abstract

(57) [Problem] To provide a hole machining method capable of machining a main hole having a branch hole branching in the middle with high accuracy and at low cost. SOLUTION: A first counterbore hole 30 having a tapered surface as a bottom surface 32 and a large-diameter second counterbore hole 31 are formed in a workpiece 10, and an eccentric portion of the bottom surface 32 has an inclined hole orthogonal to the eccentric portion. 3
4, the axially symmetrical discarded hole 36 is formed with the inclined hole 34, and the bottom of the first counterbore 30 is cored. After the cored hole 40 is formed, the pilot hole 44 is formed. Since the inclined hole 34 and the discarded hole 36 are axially symmetric, the core firs drill does not bend, the core firs hole 40 is formed with high center position accuracy, and the pilot hole drill is centered by the tapered bottom surface 46 of the core firs hole 40. , Holes 4 with high straightness
Get 4. After forming the annular groove 48 in the portion of the discarded hole 36, the first and second counterbore holes 30, 31, the core hole 40, and the prepared hole 44 are subjected to finishing by a boring tool and a reamer.
Sliding hole 10, lubrication groove 12, lubricating oil supply hole 16, fitting hole 1
Get 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drilling a hole, and more particularly to a method for drilling a main hole having a branch hole that branches off from the middle.

[0002]

2. Description of the Related Art Holes in a workpiece are processed by various methods. For example, Japanese Unexamined Patent Publication No. Hei 6-198505 discloses that in order to form an inclined hole inclined with respect to the axis of a workpiece, a counterbore having a tapered surface as a bottom face is formed in the workpiece, and the counterbore is formed. A method is described in which an inclined hole extending in a direction orthogonal to the eccentric portion is formed at an eccentric portion on the bottom surface of the hole, that is, at a portion eccentric from the axis of the counterbore hole. The angle of inclination of the bottom of the counterbore is 90 degrees with the sum of the angle of inclination of the counterbore with respect to the axis of the counterbore, and the drill bites in the direction perpendicular to the bottom of the counterbore and slides. An inclined hole is formed without any bending, and an inclined hole having high straightness without being bent can be obtained.

[0003] This hole drilling method can be used for drilling a branch hole that branches off from the middle of the main hole. For example, when a workpiece has a main hole extending along a straight line and an inclined hole extending in a direction inclined with respect to the axis of the main hole and having one end communicating with the main hole, the tapered surface is defined as a bottom surface. After forming a counterbore, forming a slanted hole from the bottom of the counterbore, then performing a core fir on the bottom of the counterbore and forming a core fir coaxially with the counterbore, then the bottom of the core fir Then, a pilot hole is formed coaxially, and a finishing process is performed on the pilot hole to obtain a main hole.

However, there is a problem that the cost is increased because the main hole is formed with high straightness. At the bottom of the counterbore hole, one end of the slanted hole is opened. The drill is easy to bend, and the core hole may be formed eccentrically.
If a pilot hole is formed from the bottom surface of the eccentric core fibrous hole, the pilot hole is bent. This bend is processed by a core drill,
Furthermore, it can be corrected by boring, but the number of finishing steps increases and the cost increases.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hole machining method capable of machining a main hole having a branch hole branching in the middle with high accuracy and at low cost. The present invention provides a hole drilling method and an oil hole drilling method according to the following embodiments. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is for the purpose of facilitating the understanding of the present invention, and should not be construed as limiting the technical features or the combinations thereof described in the present specification to the following. (1) A counterbore having a tapered surface as a bottom surface and a slope extending from an eccentric portion of the bottom surface of the counterbore hole in a direction smaller than the counterbore hole in a direction inclined with respect to an axis of the counterbore hole. A hole, a preparation step of forming a discarded hole which is opened at a position substantially symmetrical to the inclined hole with respect to the axis of the counterbore hole and having a diameter substantially equal to the inclined hole; and A boring step in which a boring is performed by a boring drill on a bottom surface of the counterbore hole that is opened at the bottom. A core drill is an ordinary drill, but is a short and hard-to-bend drill, and is shorter than a pilot hole drill described later. The pilot hole drill has a length sufficient to obtain a pilot hole of a predetermined size and must be long, but a core hole formed by machining with a core drill forms a pilot hole. In order to determine the center of the prepared hole drill, high center position accuracy is required, and the center firs are short and hard to bend, so that the center hole with high center position accuracy (less eccentricity) is formed. Is done.
The counterbore hole is formed with high center position accuracy by a drill, for example. The preparation process is performed by forming a counterbore, an inclined hole, and a discarded hole in the workpiece. The discarded hole may be formed before forming the inclined hole, or may be formed after forming the inclined hole. Since the inclined hole and the discarded hole are formed axially symmetrically on the bottom surface of the counterbore hole, the core drill does not bend when the core drill is performed on the bottom surface of the counterbore hole. If two holes are formed axially symmetrically on the bottom surface of the counterbore hole, the centering drill receives an axisymmetric cutting force with respect to the axis of the counterbore hole and does not bend in one direction. In this way, the core firs can be accurately set at the predetermined position, and a core firs hole with high center position accuracy can be obtained. Therefore, if the pilot hole is formed coaxially from the bottom surface of the core hole, the pilot hole is less bent and has a higher straightness. Therefore, when performing a finishing process on the inner peripheral surface of the prepared hole with a boring tool or a reamer to obtain a main hole with high straightness and high dimensional accuracy, for example, omit at least one of processing by a core drill and boring processing, The number of boring operations can be reduced, and a main hole with high straightness and high dimensional accuracy can be formed at low cost. (2) A counterbore process for forming a counterbore with a tapered surface as a bottom surface in a workpiece, and a counterbore from an eccentric portion of a bottom surface of the counterbore in a direction inclined with respect to an axis of the counterbore. An inclined hole forming step of forming an inclined hole extending with a smaller diameter than the counterbore, and before or after the inclined hole forming step, the inclined hole is substantially symmetric with the inclined hole with respect to the axis of the counterbore. A boring hole forming step of forming a boring hole opening with the same diameter, and a boring step of performing boring with a boring hole drill on the bottom surface of the counterbore hole in which the inclined hole and the boring hole open at an axially symmetric position. And including hole processing method. According to the method of this embodiment, as in the method described in (1), a method can be obtained in which a main hole having high straightness and high dimensional accuracy can be formed at low cost. (3) a sliding hole extending along a straight line in the workpiece;
A lubricating groove formed coaxially with the sliding hole on an inner peripheral surface in the middle of the sliding hole, and a lubricating oil extending in a direction inclined with respect to the axial direction of the sliding hole and having one end communicating with the lubricating groove. A method of forming a supply hole, wherein a counterbore step of forming a counterbore hole having a tapered surface as a bottom surface in the workpiece, and an eccentric portion of the bottom surface of the counterbore hole, the eccentric portion and An inclined hole processing step of drilling an inclined hole having a smaller diameter than the counterbore hole in a direction perpendicular to the hole, and before or after the inclined hole processing step, the inclined hole is axially symmetric with respect to the axis of the counterbore hole. In the position of 傾斜, a pitted hole processing step of processing a pitted hole that is opened with substantially the same diameter as the inclined hole, and a bottom drill of the counterbore hole in which the sloping hole and the pitted hole are opened in an axially symmetric position, A core firs process for performing a core firs and a core firs formed by the core firs process From the bottom surface, a pilot hole drilling a pilot hole extending coaxially with the core hole, using a pilot hole drill, and a finishing step of finishing the inner peripheral surface of the pilot hole processed by the pilot hole processing step. Forming a toroidal groove in the portion of the workpiece where the discarded hole is formed, at least after the core burring step, thereby eliminating almost all of the discarded hole. An oil hole forming method in which a hole whose inner peripheral surface is finished in a processing step forms the sliding hole, the inclined hole forms the lubricating oil supply hole, and the annular groove forms the lubricating groove. The annular groove may be formed after the core milling, before the pilot hole processing step, or may be formed after the pilot hole processing, before the finishing processing step, or formed after the finishing processing step. Is also good. However, if an annular groove is formed before or after the pre-hole processing and before or after the finishing step, all the hole processing, that is, counterbore hole processing, inclined hole processing, discarded hole processing, core milling and prepared hole processing are collectively performed. It can be done and is convenient. Since the inclined hole is formed in a direction almost perpendicular to the eccentric part of the bottom surface of the counterbore hole, the drill bites into the bottom surface of the counterbore hole at right angles, does not slip, and has a high center position accuracy and high straightness Is obtained. Similarly, the discarded hole is formed with high center position accuracy. Since the inclined hole and the discarded hole are formed to be axially symmetric, when performing the centering with the centering drill, the centering drill is not bent, and the centering hole is formed with high center position accuracy. And since the prepared hole drill is centered by contacting the front end surface to the bottom surface which is the tapered surface of the cored hole, the prepared hole is formed with a high straightness. If the prepared hole is formed with a high degree of straightness, it is not necessary to correct the bending of the prepared hole as in the related art, and the finishing of the prepared hole can be simplified. Further, the discarded hole can be easily formed, and in the end, according to this aspect, the sliding hole having the lubricating oil supply hole branched in the middle can be formed at a low cost with high straightness and dimensional accuracy. It becomes possible. (4) The oil hole forming method according to the above mode (3), wherein the finishing step includes at least one of boring and reaming.
Since the prepared hole is formed with a high straightness, the finishing operation can be performed only by the boring tool or only the reaming process, or the number of the boring operations can be reduced even in the case of performing both.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a workpiece 1 in which a hole is machined by an oil hole machining method according to one embodiment of the present invention.
0 is shown. The illustrated workpiece 10 is a high-pressure pump for a direct injection engine. The workpiece 10 has a sliding hole 1
2. A lubrication groove 14, a lubrication oil supply hole 16, and a fitting hole 17 for fitting an oil seal are formed. The sliding hole 12 is fitted with a sliding member (not shown) movably in the axial direction, requires high straightness and dimensional accuracy, and extends along a straight line. A lubrication groove 14 is formed coaxially with the sliding hole 12 in the inner peripheral surface 18 of the sliding hole 12.
The lubricating oil supply hole 16 has a smaller diameter than the sliding hole 12, extends in a direction inclined with respect to the axial direction of the sliding hole 12, and has one end communicating with the lubricating groove 14. The other end of the lubricating oil supply hole 16 is communicated with a lubricating oil supply port 20 formed in the workpiece 10. Lubricating oil supply port 2
0, lubricating oil is supplied by the lubricating oil supplied through the lubricating oil supply hole 16 and the lubricating groove 14.

The formation of the sliding hole 12, the lubricating groove 14, and the lubricating oil supply hole 16 will be described. The lubricating oil supply port 20
Is formed on the workpiece 10 before the formation of the sliding hole 12, the lubricating groove 14, and the lubricating oil supply hole 16,
It may be formed after the formation of the sliding hole 12, the lubricating groove 14, and the lubricating oil supply hole 16. First, as shown in FIG.
The first counterbore 30 and the second counterbore 3 are formed in the workpiece 10.
Form one. The first counterbore 30 has a tapered surface 3
2, and in the present embodiment, it is formed by a core drill (not shown). The center drill is a normal drill, but is short and hard to bend, and is shorter than a pilot hole forming a pilot hole described later, and the first counterbore 30 is formed with high center position accuracy. The tip angle of the core drill is such that the sum of the inclination angle of the bottom surface 32 of the first counterbore hole 30 and the inclination angle of the inclined hole 34 to be formed next with respect to the axis of the first counterbore hole 30 is 90 degrees. It is said. The first counterbore hole 30 is the counterbore hole described in the section of “Problems to be Solved by the Invention, Problem Solving Means, Functions and Effects”, and the step of forming the first counterbore hole 30 is a counterbore step. It is. After forming the first counterbore hole 30, a second counterbore hole 31 having a larger diameter than the first counterbore hole 30 is formed coaxially with the first counterbore hole 30 by boring or the like.

Next, the first counterbore 30 is formed in the workpiece 10.
The diameter of the first counterbore 30 is smaller than that of the first counterbore 30 in a direction inclined from the eccentric portion of the bottom surface 32 of the bottom face, that is, the portion eccentric from the axis of the counterbore, with respect to the axis of the first counterbore 30. Is formed by a drill (not shown). The drill is inserted into the first counterbore 30 through the second counterbore 31. The inclination angle of the bottom surface 32 of the first counterbore hole 30 is set to be such that the sum of the inclination angle of the inclined hole 34 with respect to the axis of the first counterbore hole 30 is 90 degrees. When the drill is inclined at an angle equal to the inclination angle of the inclined hole 34 with respect to the axis of the counterbore 30, the drill is in a state orthogonal to the eccentric portion of the bottom surface 32 of the first counterbore 30, and is perpendicular to the bottom surface 32. The first counterbore 30 does not bite, slips, and extends from the eccentric portion of the bottom surface 32 of the first counterbore 30 in a direction orthogonal to the eccentric portion and inclined with respect to the axis of the first counterbore 30. An inclined hole 34 extending with a smaller diameter and having high center position accuracy and straightness is obtained.
The step of forming the inclined hole 34 by a drill is an inclined hole forming step, and is an inclined hole processing step.

Next, the first counterbore 30 is formed in the workpiece 10.
A drilled hole 36 having the same diameter as the inclined hole 34 is formed by drilling at a position axially symmetrical with the inclined hole 34 with respect to the axis of the first counterbore hole 30 on the bottom surface 32 of the base plate 32 in an axially symmetric manner with the inclined hole 34. I do. The discarded hole 36 is inclined with respect to the axis of the first counterbore 30 at an angle equal to the inclination angle of the inclined hole 34 with respect to the axis of the first counterbore 30.
The eccentric part is formed in a direction orthogonal to the eccentric part, and the discarded hole 36 is also formed with high center position accuracy similarly to the inclined hole 34. Pit 3
The step of forming No. 6 is a discard hole forming step, which is a discard hole processing step. The step of forming the first counterbore hole 30, the inclined hole 34, and the discarded hole 36 as described above is a preparation step.

Next, as shown in FIG.
1 and counterbore 36 open at axially symmetric positions
The core is drilled on the bottom surface 32 of the “0” with a core drill (not shown) to form a core hole 40. The diameter of the core hole 40 is actually the same as the diameter of the first counterbore 30. However, in FIG. It is shown with a small diameter. On the bottom surface 32 of the first counterbore 30, an inclined hole 34 and a discarded hole 36 are formed axially symmetrically at an axially symmetric position.
When performing the center fir on the bottom surface 32 with the center fir drill, the center fir drill receives an axially symmetric cutting force with respect to the axis of the first counterbore 30, and does not bend in one direction. This can be performed accurately at the predetermined position, and the core hole 40 with high center position accuracy can be obtained. The step of performing a core fir using a core fir drill is a core fir step.

Next, as shown in FIG. 2C, a pilot hole 44 extending coaxially with the core hole 40 is formed from a bottom surface 46 of the core hole 40 by a pilot hole drill (not shown). Pilot hole 4
The diameter of 4 is actually the same as the diameter of the first counterbore 30 and the core hole 40, but FIG. It is shown with a small diameter. When the pilot hole 44 is formed by the pilot hole drill, the pilot hole drill is centered by the core hole 40. The tip end surface of the prepared hole drill is in contact with the bottom surface 46 (see FIG. 2B) which is a tapered surface of the core fibrous hole 40 and is centered. By centering the hole drill, a pilot hole 44 extending coaxially with the core hole 40 is formed straight from the bottom surface 46 of the core hole 40. The step of processing the prepared hole 44 is a prepared hole processing step.

Next, as shown in FIG.
An annular groove 48 is formed in a portion where 6 is formed. As a result, the pit 36 is eliminated. This annular groove 48
The step of eliminating the discarded holes 36 by forming the groove is a groove processing step. In the present embodiment, the inclined holes 34,
The drilling of the discarded hole 36, the core hole 40, and the prepared hole 44 is performed collectively prior to the formation of the annular groove 48. After the formation of the annular groove 48, the inner peripheral surfaces of the first counterbore hole 30, the second counterbore hole 31, the core hole 40, and the pilot hole 44 are subjected to finishing. First, machining is performed using a boring tool, which is a type of boring tool (not shown), and then finishing is performed using a reamer.
The process of performing finishing in this way is a finishing process,
As shown in FIG. 2E, the first counterbore hole 30 and the pilot hole 44, the inner peripheral surface of which is finished in the finishing step, constitute the sliding hole 12, and the inclined hole 34 is the lubricating oil supply hole 16 The annular groove 48 constitutes the lubrication groove 14, and the second counterbore hole 31 constitutes the fitting hole 17. Branches from the middle,
The lubricating oil supply hole 16 is inclined with respect to the axial direction, and the sliding hole 12 with high straightness and dimensional accuracy can be obtained at low cost.

Incidentally, the diameters of the counterbore holes (counterbore holes in which an inclined hole and a discarded hole are formed in the tapered bottom surface), the core hole and the pilot hole need not be the same, and may be different. The diameter of the core hole is smaller than the diameter of the counterbore, and the diameter of the pilot hole is smaller than the diameter of the core hole. The diameter of the counterbore and the core hole may be the same, the diameter of the pilot hole may be smaller than the diameter of the counterbore and the core hole, and the diameter of the core and the pilot hole may be the same. It may be smaller than the diameter.

Further, the counterbore hole (a counterbore hole in which an inclined hole and a discarded hole are formed in the tapered bottom surface) and the core hole may be formed by different drills.

Although the embodiments of the present invention have been described in detail above, these are literal examples, and the present invention is described in the above section [Problems to be Solved by the Invention, Problem Solving Means, Functions and Effects]. Various modifications and improvements can be made based on the knowledge of those skilled in the art, including the embodiment described above.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a workpiece on which a sliding hole, a lubrication groove, and a lubrication oil supply hole are formed by an oil hole drilling method according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the formation of the sliding hole, the lubricating groove and the lubricating oil supply hole in the order of steps.

[Explanation of symbols]

10: Workpiece 12: Sliding hole 14: Lubrication groove
16: Lubricating oil supply hole 30: First counterbore hole 32: Bottom surface 34: Inclined hole
36: pit hole 40: core hole 44: pilot hole 4
8: annular groove

Claims (1)

[Claims] 1. A counterbore having a tapered surface as a bottom surface and an eccentric portion of the bottom surface of the counterbore hole having a smaller diameter than the counterbore hole in a direction inclined with respect to the axis of the counterbore hole. An inclined hole extending, a preparation step of forming a discarded hole that is opened with a diameter substantially equal to the inclined hole at a position axially symmetrical to the inclined hole with respect to the axis of the counterbore hole; and A boring step of performing boring with a boring drill on a bottom surface of the counterbore hole that opens at a symmetrical position.