JPH0985533A - Reamer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the accuracy in boring at a high level even if the same reamer is used for a long period by providing an energizing means threadingly engaging a shaft end to energize a steel ball toward a tapered hole in the tip according to the threadingly engaging position. SOLUTION: An energizing means 8 consists of a female screw tapped in the inner periphery of a hollow hole 5 opening to the tip end 1a and a bolt 8c having a male screw cut on the outer periphery to threadingly engage the female screw. Even if a cutting edge 2 is worn as it is used and thereby the accuracy of a product hole is degraded, the bolt 8c is screwed further into the female screw before the allowable limit of the degradation is exceeded so that the wall thickness of the reamer is bulged again through a steel ball 7 and expander and the cutting edge surface of the cutting edge 2 is correctively restored to the apparently unworn condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reamer used for precision drilling of various workpieces such as hydraulic parts, pneumatic parts and automobile parts.

[0002]

2. Description of the Related Art When machining a cylinder bore of a hydraulic motor, a spool hole of a hydraulic control valve, or the like, first, a workpiece is drilled. However, the hole is not a perfect circle and often does not penetrate straight. The reason is that the drill is only fitted on the main spindle of the drilling machine at the shank portion, and due to slight disparity of the cutting edge, when the hole bends to one side, it advances in that direction. Therefore, in order to further process this hole to form a clean hole with a high dimensional accuracy on the finished surface, the hole is removed by using a reamer.

FIG. 9 shows a partial front cross-sectional view of a conventional reamer, and FIGS. 10 to 12 are respectively FF in FIG.
It is a line sectional view, a GG line sectional view, and a HH line sectional view. As is clear from these figures, this reamer 101 has cutting blades 102 of extremely high hardness formed on the outer periphery in the vicinity of the tip portion, and has substantially the same shape for properly inserting the cutting blades 102 into the holes on both sides thereof. Diameter pilot guides 103, 104 are formed. Then, insert the reamer 101 into the hole drilled while rotating it,
The inner circumference of the hole is cut by moving the cutting blade 102 along the inner circumference of the hole while guiding with 03, 104.

[0004]

However, the cutting blade 10
No. 2 has hardness, but wears inevitably because it cuts a high-hardness workpiece such as an aluminum alloy. For this reason, if the same reamer is used for a long period of time, the hole machining accuracy will gradually deteriorate, resulting in deterioration of product quality and eventually yield reduction. Conversely, frequent replacement of the reamer will increase running costs and increase operating efficiency. There is a dilemma that leads to decline.

An object of the present invention is to provide a reamer that effectively solves such a problem.

[0006]

In order to achieve the above object, the present invention employs the following configuration.

That is, the reamer of the present invention has a cutting blade on the outer circumference, and a hollow hole bored in the wall thickness from the shaft end portion along the shaft center and inserted into this hollow hole. Extension located inside the cutting blade and opening a taper hole on the shaft end side, a hard sphere arranged at a position adjacent to the taper hole of this extension, and a screw threaded on the shaft end part. And a biasing means for biasing the hard sphere toward the taper hole at the tip according to the mounting position.

In the reamer constructed as above,
The deeper the screwing position of the biasing means, the deeper the hard ball enters into the taper hole of the extension and expands the taper hole and thus the outer diameter of the extension. Along with this, the meat of the reamer located further on the outer periphery of the extension swells, and the cutting edge surface of the cutting blade formed on the reamer is moved to a position where the diameter is expanded. Therefore, if adjustment is performed by the biasing means before the wear of the cutting blade exceeds the allowable limit, the cutting blade can be corrected to an appropriate state with no apparent wear without replacing the reamer. Particularly, in the present invention, since the positioning mechanism composed of the hard sphere and the tapered hole is interposed between the biasing means and the extension, the biasing force of the biasing means can be uniformly converted into the expansion force of the extension. Therefore, the above correction can be performed with high accuracy.

As described above, according to the present invention, even if the same reamer is used for a long period of time, it is possible to maintain a high level of precision in drilling, which is an excellent effect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS.

The reamer of this embodiment is used, for example, in the forklift control valve A shown in FIG. 8 to improve the surface accuracy of the spool holding hole a. In this type of forklift control valve A, if the machining accuracy of the spool holding hole a is low, when the spool (not shown) is mounted and the cylinder ports B and C are blocked by the land, for example, the spool and the spool holding hole a. This causes an extremely dangerous situation such as oil leaking from the gap between the load and the load falling off. Therefore, as one of the conditions for surely avoiding such a situation, it is necessary to provide the spool holding hole a with high accuracy, and for that purpose, the spool holding hole a drilled is further reaped using a reamer. .

In the reamer 1 of this embodiment, the error of the hole a shown in FIG.
It is intended to be in the range of α (α is several μm to several tens of μm).

FIG. 1 is a front sectional view of the reamer 1, and FIG. 2 is an enlarged sectional view of an essential part of the reamer 1 which is disassembled.
6 is a sectional view taken along the line AA in FIG. 1 and FIG.
FIG. 7 is a sectional view taken along line C-C, sectional view taken along line D-D, and FIG. 7 is a view taken in the direction of arrow E in FIG. 1.

As shown in these drawings, the reamer 1 has a cutting blade 2, a first pilot guide 3 and a second pilot guide 4 on the outer circumference, and a hollow hole 5 and a hollow hole 5 in its thickness. An extension 6 and a rigid ball 7 housed in the hollow hole 5 and a biasing means 8 for biasing the rigid ball 7 toward the extension 6.

The cutting blade 2 is formed in the vicinity of the tip portion 1a of the reamer 1, and specifically, as shown in FIG. 4, blade holding portions 2a are provided at four outer circumferences at the same pitch. , The borazon 2b on the leading side in the rotation direction of the blade holding portion 2a.
Is formed by brazing. The cutting blade 2 has, for example, a maximum diameter φB ₁ of 14.99 mm to 15.
300 mm, the diameter [phi] B ₂ of the blade holding portion 2a is 14.3 mm, the margin M _B of the blade holding portion 2a including borazon 2b 4.8
is set to mm.

The first pilot guide 3 is formed adjacent to the cutting blade 2 on the side of the tip portion 1a of the reamer 1. Specifically, as shown in FIG.
The guide surface 3a is projectingly provided at four positions on the outer periphery at the same phase and pitch as the blade holding portion 2a of No. 1, and the guide surface 3a is subjected to diamond electrodeposition. The guide surface 3a has a maximum diameter φA of 14.88 mm to 14.90 mm and a margin M _A.
Is set to 4.8 mm.

The second pilot guide 4 is formed adjacent to the cutting blade 2 on the side of the base end portion 1b of the reamer 1. Specifically, as shown in FIG. Two
The blade holding portion 2a and the guide surface 3a of the first pilot guide 3 are provided with projecting guide surfaces 4a at four positions on the outer periphery at the same phase and at the same pitch, and diamond electro-deposition is applied to the guide surface 4a. . The guide surface 4a has a maximum diameter φC of 14.990 to 14.995 mm and a margin M _C of 4.8 mm.

The hollow hole 5 is bored from the tip portion 1a of the reamer 1 to a predetermined depth along the axis m of the reamer 1, and has a constant inner diameter near the inlet of the hollow hole 5. The taper surface 5a having a slope of 5 ° is machined so that the diameter gradually decreases from there to the inner part.
Are formed. This taper surface 5a is just the reamer 1
It is located on the inner circumference of the portion where the cutting blade 2 is provided.

The extension 6 is a frusto-conical shape having a hole 6a penetrating the center thereof, and a step 6b is formed on a part of the outer diameter thereof. Then, when this extension 6 is inserted into the hollow hole 5 of the reamer 1 in a normal manner, that is, without exerting a particularly large pressing force, the step 6b on the outer periphery of the extension 6 near the inside of the cutting blade 2 It is adapted to be attached to the entrance of the tapered surface 5a. Then, by cutting the opening end entrance of the extension 6, a tapered surface 6c having a maximum diameter of 5.5 mm and an inclination of 45 ° is formed.

The hard sphere 7 is made of steel, for example, and its diameter is set to 5.5 mm in consideration of the tapered surface 6c.

The urging means 8 is a tip portion 1a of the reamer 1.
It is composed of a female screw 8a screwed on the inner circumference of the hollow hole 5 opening to the inside, and a bolt 8c having a male screw 8b screwed on the female screw 8a engraved on the outer circumference. 7 is formed with a partially spherical hole 8d having substantially the same curvature, which can be evenly provided on the outer peripheral surface. Instead of the hole 8d, a hard sphere may be biased by a tapered surface. The head of the bolt 8c is set to be smaller than the maximum outer shape of the reamer 1.

First, after inserting the extension 6 into the hollow hole 5 of the reamer 1, the hard ball 7 is inserted into the hollow hole 5, and the male screw 8b of the bolt 8c is screwed into the female screw 8a of the reamer 1. By applying a predetermined tightening force to the bolt 8c, the reamer 1 is assembled while the hard sphere 7 is in pressure contact with the tapered surface 6c of the extension 6.

From the base end 1b side of the reamer 1, an introduction hole 1c for introducing cutting oil along the axis m.
The introduction hole 1c is formed in the reamer 1 through the grooves 1d formed at four positions in the vicinity of the inner end portion at a predetermined spiral pitch.
It is designed to be guided to the outer circumference of. Also, this reamer 1
A cutting oil guide cover 1e is fitted on the outer periphery of the groove 1d at a position where the groove 1d is closed, and the direction of the flow of the oil flowing into the groove 1d is further converted to the axial center direction of the reamer 1 so that the reamer 1 1 is ejected toward the tip portion 1a (see the arrow in FIG. 1).

In the reamer 1 thus constructed, the deeper the screwing position of the bolt 8c is, the deeper the rigid ball 7 enters the tapered hole 6c of the extension 6 and the tapered hole 6c.
c, and then expand the outer diameter of extension 6. Along with this, the reamer 1 located further outside the extension 6
The meat bulges out and the blade tip surface of the borazon 2b of the cutting blade 2 formed on the reamer 1 is positioned at a position where the diameter is expanded. Therefore, when the reamer 1 is initially used, that is, when the cutting blade 2 is not worn, the bolt 8
After screwing c to an appropriate position, the drilled hole is exposed experimentally and the bolt tightening position is adjusted by the machining error of the hole. You can get as close as possible. Moreover, even if the cutting blade 2 wears as it is used, and the accuracy of the hole in the product decreases accordingly, if the bolt 8c is further screwed in before it exceeds the allowable limit, the bolt 6 can be inserted through the extension 6. It is possible to perform a correction in which the meat of the reamer 1 is swollen again and the blade tip surface of the cutting blade 2 is apparently restored to a state in which it is not worn. Particularly, in the present embodiment, since the positioning mechanism including the hard ball 7 and the tapered hole 6c is interposed between the biasing means 8 and the extension 6, the biasing force of the biasing means 8 is increased by increasing the diameter of the extension 6. Can be converted evenly into force,
The correction can be performed with high accuracy.

As described above, according to this embodiment, even if the same reamer 1 is used for a long period of time, the excellent effect that the precision of the drilling process can be maintained at a high level is achieved. Moreover, such correction is also useful in absorbing a subtle dimensional error when the tool (reamer) is replaced.

In addition to the above, the reamer 1 of this embodiment is also different from the conventional one in the pilot guides 3 and 4, and this point also greatly contributes to improving the drilling accuracy. . That is, the conventional pilot guides 103 and 104 shown in FIGS. 9 to 12 are made of cemented carbide, and the margin M of the guide surface is extremely narrow, about 1 mm, in order to prevent seizure. . Therefore, there is a problem that a large gap is generated between the machined hole and the pilot guide, a sufficient guiding action cannot be obtained, and the roundness and cylindricity become poor. On the other hand, in the present embodiment shown in FIGS. 3 and 5, the guide surface 3
By applying diamond electrodeposition to a and 4a, the risk of seizure is significantly reduced, resulting in a margin of 4.8.
mm, which is significantly wider than the conventional one, which reduces the gap between the machining hole and the pilot guide, stabilizes the movement of the cutting edge, and improves the roundness of the hole. The excellent effect of dramatically improving the cylindricity is achieved. Further, in the present embodiment, the cutting oil is ejected in the axial direction as indicated by the arrow in FIG. 1, so that when it is ejected in the radial direction indicated by the arrow in the figure through the groove 101d as shown in FIG. Compared to
The oil can be more accurately supplied to the cutting portion.

The specific structure of each part is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing an exploded main part of the same embodiment.

FIG. 3 is a sectional view taken along line AA in FIG. 1;

FIG. 4 is a sectional view taken along line BB in FIG.

5 is a cross-sectional view taken along the line CC in FIG.

6 is a cross-sectional view taken along the line DD in FIG.

FIG. 7 is a view on arrow E in FIG.

FIG. 8 is a cross-sectional view showing a spool holding hole portion of a forklift control valve that is an application example of the present invention.

9 is a front sectional view corresponding to FIG. 1 showing a conventional example.

FIG. 10 is a sectional view taken along line FF in FIG. 9;

11 is a sectional view taken along line GG in FIG.

12 is a cross-sectional view taken along line HH in FIG.

[Explanation of symbols]

 1 ... Reamer 2 ... Cutting blade 5 ... Hollow hole 6 ... Extension 7 ... Hard sphere 8 ... Energizing means

Claims (1)

[Claims] 1. A reamer having a cutting blade on the outer periphery, wherein a hollow hole is bored in a wall thickness along the shaft center from the shaft end, and the cutting blade is inserted into the hollow hole. Extension located inside the shaft end with a taper hole on the shaft end side, a hard sphere arranged at a position adjacent to the taper hole of this extension, and screwed to the shaft end depending on the screwing position. And a biasing means for biasing the hard sphere toward the taper hole at the tip of the reamer.