JP2003025120A - Boring method and boring tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boring method and a boring tool capable of performing highly accurate coaxial boring by means of a machining center without using a boring tool of a complex structure and a special purpose machine tool capable of rotating such boring tool and driving it to advance and retract. SOLUTION: A boring tool 40 comprises a cutting edge tip 91 out of a plurality of cutting edge tips fixed to a tool body 50 driven to rotate around a rotary axis line X, and other cutting edge tips 71 and 81 mounted on the tool body 50 so that a position along the rotary axis line and angle in relation to the fixed cutting edge tip 91 can be adjusted. All of a plurality of valve seat faces 21, 22 and 23 having a plurality of stages are formed simultaneously by means of a plurality of cutting edge tips 71 and 81.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve seat surface in a cylinder head of an engine,
The present invention relates to a hole drilling method and a hole drilling tool for forming, in an opening of a drilled hole formed in a workpiece, a plurality of drilled surfaces having different tilt angles with respect to the axis of the drilled hole.

[0002]

2. Description of the Related Art A cylinder head which is an engine part of an automobile is provided with a valve seat surface which is opened and closed by a valve head of an intake valve and an exhaust valve, and a valve guide hole which guides a stem portion of each valve. . Since the valve seat surface and the valve guide hole greatly affect the engine performance, it is required to be processed with high precision (for example, Japanese Patent Laid-Open No. 6-2.
97282). That is, the valve guide hole is required to be machined with high accuracy so that the hole diameter, surface roughness and roundness satisfy predetermined dimensional tolerances. The valve seat surface is composed of a plurality of steps (for example, three steps) of tapered surfaces having different inclination angles with respect to the axis of the machined hole, and the surface angle, diameter, surface position, surface width, and surface roughness are set for each surface. High precision machining is required so that the degree satisfies a predetermined dimensional tolerance. Further, it is required that the coaxiality between the valve seat surface and the valve guide hole is ensured and the surface runout of the valve seat surface with respect to the valve guide hole satisfies a predetermined dimensional tolerance.

As a conventional drilling tool, Japanese Patent No. 2748
The one disclosed in Japanese Patent Publication No. 846-274849 is known. In this hole drilling tool, a reamer is attached to the tip of a substantially conical tool body rotated about a rotation axis so as to be able to move back and forth along the axis. At the root of the reamer, a three-step tapered surface is formed at the opening of the machined hole. 3
Two cutting edge tips are attached. Of these three cutting blade tips, the two cutting blade tips forming the tapered surface on the inner side of the processing hole and the tapered surface on the opening edge side are directly attached to the tool body. On the other hand, the remaining one cutting edge tip that forms a tapered surface located between the two tapered surfaces is attached to a slider that is slidable along the generatrix direction of the cone formed by the tool body.

Finishing of the inner peripheral surface of the machined hole and machining of the tapered surface of the opening using such a hole machining tool are performed as follows. First, with the reamer retracted,
With the axis of rotation coaxial with the center line of the machining hole, the tool body is advanced while rotating, and the two cutting blade tips form a taper surface on the hole back side and a taper surface on the opening edge side of the opening. Then, the slider is slid to form an intermediate tapered surface by the remaining one cutting edge tip. Then, the reamer is moved forward to finish the inner circumference of the processed hole.

[0005]

However, in the above hole drilling tool, the slider is slid so that the cutting edge tip attached to the slider is positioned coaxially with the other two cutting edge tips. Therefore, the structure of the drilling tool itself becomes extremely complicated. Moreover, since a machine tool for rotating and advancing and retracting this hole drilling tool must be provided with a mechanism for operating the mechanism, a dedicated machine tool is naturally required, and a general-purpose machining center or the like is used. Drilling is not possible.

On the other hand, in recent years, from the viewpoint of reducing the manufacturing cost, it has been strongly demanded to construct a flexible production line. Therefore, a general-purpose machining center or the like is used, and a hole is highly accurately formed. It is required to carry out processing.

The present invention has been made under such a background, and does not require a hole drilling tool having a complicated structure and a dedicated machine tool for driving the tool to rotate and move back and forth.
An object of the present invention is to provide a hole drilling method and a hole drilling tool capable of drilling holes with high coaxiality by a general-purpose machining center or the like.

[0008]

The objects of the present invention are achieved by the following means.

(1) A hole drilling tool having a plurality of cutting blade tips is rotated on each of a plurality of stages of machined surfaces having different inclination angles with respect to the axis of the machined hole at the opening of the machined hole formed in the workpiece. In a hole drilling method of rotating and driving around an axis, one cutting blade tip among a plurality of cutting blade tips forming each of the machining surfaces is fixedly attached, and another cutting blade tip is the one. A hole drilling method, wherein all of the plurality of stages of machined surfaces are formed at the same time by using a hole drilling tool which is relatively adjustable in position and angle relative to the cutting edge tip along the rotation axis.

(2) In a hole drilling tool having a plurality of cutting edge tips for forming a plurality of stepped surfaces each having a different inclination angle with respect to the axis of the drilled hole at the opening of the drilled hole formed in the workpiece. , One of the plurality of cutting blade tips is fixedly attached to a tool body that is rotationally driven around a rotation axis, and another cutting blade tip is attached to the fixed one cutting blade tip. A hole drilling tool, characterized in that it is attached to the tool body so that the position and angle along the axis of rotation can be adjusted relative to each other, and all of the plurality of cutting surfaces are simultaneously formed by the plurality of cutting blade tips.

(3) A hole drilling tool according to the above (2), characterized in that a reamer for finishing the inner peripheral surface of the drilled hole is attached to the tip of the tool body along the axis of rotation. .

(4) The hole drilling tool according to (3) above, wherein the reamer finishes the inner peripheral surface of the drilled hole which has been previously subjected to counterbore processing.

(5) The hole drilling tool according to (3) above, wherein the reamer is provided with an end mill blade portion having a diameter smaller than the diameter of the reamer at the tip thereof.

(6) The hole drilling tool according to (3), wherein the reamer has a coolant supply groove for supplying a coolant to a cutting edge provided at a tip end portion, which is formed on an outer peripheral surface.

[0015]

The present invention configured as described above has the following effects.

According to the first aspect of the present invention, a plurality of holes are formed in the opening of the machined hole by a machine tool such as a general-purpose machining center without using a hole-machining tool having a complicated structure or a dedicated machine tool. A stepped surface can be formed, and a flexible production line can be constructed. Moreover, since all of the processed surfaces in multiple stages are formed at the same time, high coaxiality can be easily ensured, and for each processed surface that has been finished,
It becomes possible to give a higher forming accuracy than the processing by the conventional dedicated machine.

According to the invention of claim 2, claim 1
In addition to the effects similar to those of the invention described in (1), the structure of the hole drilling tool itself is simplified, and the tool cost can be reduced. In particular, a fixed one of a plurality of cutting edge tips
Since one cutting edge tip is attached to the tool body so that other cutting edge tips can be adjusted relative to each other, it is easy to adjust the other cutting edge tips, prevent work mistakes during setting, and reduce setting time. There are advantages that it can be reduced, the space of the fixed-side cutting blade tip occupying in the tool body can be reduced, the rigidity of the tool body can be improved, and the position of the cutting blade along the rotation axis does not change significantly.

According to the third aspect of the present invention, since the reamer finishes the inner peripheral surface of the machined hole and is guided to the machined hole, the machined hole and a plurality of stages of machined surfaces are highly coaxial. It becomes possible to secure with accuracy.

According to the invention as set forth in claim 4, the counterbore formed at the mouth of the machined hole prevents the reamer from being bent following the prepared hole of the machined hole, and the machined hole and a plurality of machined surfaces are formed. It is possible to secure the coaxiality of the with higher accuracy.

According to the invention of claim 5, since the end mill blade portion is difficult to follow the prepared hole of the machined hole, the reamer allows the reamer to prepare the machined hole without forming a counterbore in advance. Therefore, it is possible to prevent the bending of the machined hole and the coaxiality between the machined hole and the machined surfaces of a plurality of steps with higher accuracy.

According to the invention of claim 6, a sufficient amount of coolant is supplied to the cutting edge through the coolant supply groove formed on the outer peripheral surface of the reamer, so that the entire cutting edge is efficiently cooled. , The drilling accuracy is stable. Further, the diameter of the center hole for the coolant through can be made as small as possible or can be eliminated, the rigidity of the reamer is improved, and the reamer itself can be easily manufactured.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the valve seat surfaces 21, 22, 23.
And a sectional view showing a main part of the cylinder head 10 in which the valve guide hole 31 is formed. FIG. 2 is a schematic configuration diagram showing a hole drilling tool 40 according to an embodiment of the present invention, FIG.
(B) shows lines 3A-3A and 3B- in FIG. 2, respectively.
3B is a sectional view taken along the line 3B, FIG. 4 is a perspective view showing the first cutting edge portion 70 shown in FIG. 2, and FIGS. 5A and 5B are for adjusting the position and inclination angle of the first cutting edge tip 71. It is a figure with which explanation of the work to do is offered.

Referring to FIG. 1, an aluminum cylinder head 10 as a workpiece has a valve seat 20.
And a valve guide 30 formed of a sintered material or the like are inserted. The hole portions of the valve seat 20 and the valve guide 30 correspond to processed holes.

The opening of the valve seat 20 has a plurality of stages (three stages in the illustrated example) opened and closed by a valve (not shown).
Valve seat surfaces 21, 22, and 23 (corresponding to processed surfaces) are formed. Each valve seat surface 21, 22,
No. 23 has a different inclination angle with respect to the axis of the machined hole, the first valve seat surface 21 located on the far side of the hole forms an angle θ1, and the third valve seat surface 23 located on the opening edge side forms an angle θ3. The second valve seat surface 22 located between the valve seat surface 21 and the third valve seat surface 23 makes an angle θ2. Each valve seat surface 21, 22,
No. 23 must be machined with high precision so that the surface angle, diameter, surface position, surface width, and surface roughness satisfy predetermined dimensional tolerances. Since the airtightness is maintained by bringing the seat portion of the valve (not shown) into close contact with the second valve seat surface 22, the valve seat diameter φD1 and the valve seat width W are
Especially, it becomes an important dimension.

A stem portion of the valve is fitted into a through hole 31 of the valve guide 30 (hereinafter referred to as a valve guide hole) and has a function of guiding the movement of the stem portion. Therefore, the inner peripheral surface of the valve guide hole 31 must be machined with high accuracy so that the hole diameter, surface roughness, and roundness satisfy predetermined dimensional tolerances. It is also necessary to ensure high coaxiality between the center line of the valve seat and the center line of each valve seat surface 21, 22, 23.

The valve seat surfaces 21, 22, 23 and the valve guide hole 31 are formed or finished by using a hole drilling tool. As shown in FIGS. 2 and 3 (A), the hole drilling tool 40 of this embodiment has a valve seat surface 2
It has a plurality of cutting edge tips 71, 81, 91 forming 1, 22, 23 respectively. Multiple cutting edge tips 7
One of the cutting blade tips 91 among 1, 81 and 91 is fixedly attached to the tool body 50 that is rotationally driven around the rotation axis X. The other two cutting blade tips 71, 81
Is attached to the tool body 50 so that the position and angle along the rotation axis X with respect to the fixed one cutting blade tip 91 can be adjusted relatively. Furthermore, the tool body 5
A reamer 60 for finishing the inner peripheral surface of the valve guide hole 31 is attached to the front end portion of 0 along the rotation axis X.

More specifically, the tool main body 50 has a substantially multi-stage cylindrical shape with the rotation axis X as the center, and the tip end side thereof is formed into a substantially truncated cone shape whose diameter gradually decreases. Although not shown, an arbor portion for connecting the tool body 50 to a drive shaft of a machine tool such as a general-purpose machining center is provided at the rear end of the tool body 50, and the tool body 50 is connected to the ATC (automatic tool of the machine tool). A grip portion for gripping by the arm of the exchange device) is provided. The hole drilling tool 40 connected to the drive shaft of the machine tool is rotationally driven around the rotation axis X in the tool rotation direction indicated by the symbol T, and further fed and moved forward and backward along the rotation axis X.

As shown in FIG. 3A, the tool body 50 is provided with first to third mounting recesses 51 to 53 having an L-shaped cross section orthogonal to the axis, and the first valve seat surface 21. The first cutting edge portion 70 to be processed is arranged in the first mounting recess 51. Similarly, the second cutting edge portion 80 that processes the second valve seat surface 22 is disposed in the second mounting recess 52, and the third cutting edge portion 90 that processes the third valve seat surface 23 is the third mounting recessed portion 5.
It is located at 3. Each of the mounting recesses 51 to 53 has a surface parallel to the rotation axis X.

As shown in FIGS. 4 and 5, the first cutting blade portion 70 has a substantially rectangular prism-shaped first cartridge 72 having a first cutting blade tip 71 forming the first valve seat surface 21 mounted on the tip thereof. A longitudinal direction adjusting means 100 for finely adjusting the position of the first cartridge 72 along the rotation axis X, and an angle adjusting means 110 for finely adjusting the angle of the first cutting edge tip 71,
Have. In the first cartridge 72, a substantially central portion in the longitudinal direction is cut off to form an inclined concave portion 73, and a long hole 74 extending in the longitudinal direction of the first cartridge 72 is formed through the inclined concave portion 73. . After finely adjusting the position of the first cartridge 72 and the angle of the first cutting edge tip 71, the cartridge clamp screw 7 inserted into the long hole 74
By fastening 5 to the tool body 50, the first cartridge 72 is fixed to the tool body 50.

The longitudinal adjusting means 100 is composed of, for example, an adjusting screw 101, and the right end of the adjusting screw 101 in the drawing is in contact with the vertical wall 51a of the first mounting recess 51. By rotating the adjusting screw 101 in the proper forward and reverse directions, the amount of protrusion of the adjusting screw 101 from the end surface of the first cartridge 72 is changed, whereby the position of the first cartridge 72 in the longitudinal direction is finely adjusted.

The angle adjusting means 110 includes the first mounting recess 51.
And a screw hole 111 formed through the first cartridge 72 in a direction orthogonal to the surface of the
Angle adjusting screw 11 which is screwed into and can project from the lower surface of the first cartridge 72 toward the surface of the first mounting recess 51.
2 and. As shown in FIG. 5A, when the angle adjusting screw 112 is not used, that is, the first cartridge 7
When the lower surface of 2 is brought into close contact with the surface of the first mounting recess 51, the angle formed by the rotation axis X and the first cutting edge tip 71 is set to the angle A. The angle A is the maximum allowable angle. On the other hand, as shown in FIG. 5B, when the angle adjusting screw 112 is turned to project from the lower surface of the first cartridge 72, the first cartridge 72 is rotated or elastically deformed around the cartridge clamp screw 75 as a fulcrum to rotate. The angle formed by the axis X and the first cutting edge tip 71 is finely adjusted to the angle B.

Referring to FIG. 2, the second cutting blade portion 80 similarly has a substantially rectangular prism-shaped second cartridge 82 having a second cutting blade tip 81 forming the second valve seat surface 22 mounted at its tip. It has longitudinal direction adjusting means 100 for finely adjusting the position of the second cartridge 82 along the rotation axis X, and angle adjusting means 110 for finely adjusting the angle of the second cutting edge tip 81. It should be noted that reference numerals 83, 84, and 85 in FIG. 2 respectively indicate an inclined concave portion, a long hole, and a cartridge clamp screw similar to the first cutting edge portion 70.

The third cutting edge portion 90 is provided on the third valve seat surface 2
It has a third cutting edge tip 91 which forms 3.

First, second and third cutting edge tips 71,
Reference numerals 81 and 91 denote throw-away tips formed of a hard material such as cemented carbide and have a substantially equilateral triangular flat plate shape of the same shape and size. In each of the cutting blade tips 71, 81, 91, one equilateral triangular surface is a rake surface, and the cutting blades are formed at three side edge portions of this rake surface. Each of the valve seat surfaces 2 can be cut by a cutting blade that is directed outward in the radial direction of the tool body 50.
1, 22, 23 are formed. The first cutting edge tip 71 and the second cutting edge tip 81 have tip clamps 76, 86 on the tip mounting seats formed at the tips of the cartridges 72, 82.
It is detachably attached by. On the other hand, the third cutting edge tip 91 is removably mounted on the surface of the third mounting recess 53 directly by the tip clamp 96.

FIG. 6 shows the rotation loci of the first, second and third cutting blade tips 71, 81, 91 about the rotation axis X and the first cutting blade tips 71, 81, 91. , Second and third valve seat surfaces 21, 22, 23
It is a figure which shows and.

As shown, the second cutting edge tip 81 is
The first cutting edge tip 71 is arranged slightly offset from the third cutting edge tip 91 toward the tip side of the tool main body 50 and closer to the rotation axis X, and the first cutting edge tip 71 is positioned more than the second cutting edge tip 81.
Is slightly displaced toward the front end side and closer to the rotation axis X. The inclination angle of the second cutting edge tip 81 with respect to the rotation axis X of the cutting edge is set to be smaller than the inclination angle of the third cutting edge tip 91 with respect to the rotation axis X of the cutting edge of the first cutting edge tip 71. The inclination angle with respect to the rotation axis X is set smaller than the inclination angle with respect to the rotation axis X of the cutting edge of the second cutting edge tip 81. And the first to third cutting edge chips 7
1, 81 and 91 are arranged so that the rotation loci about the rotation axis X intersect.

With reference to FIG. 2, the reamer 60 is mounted coaxially with the rotation axis X in a mounting hole formed in the tool body 50 along the rotation axis X. The protruding amount of the reamer 60 is adjusted by an adjusting screw (not shown). A coolant supply hole 54 is formed in the tool body 50, and the coolant is supplied to the base end of the reamer 60 via the coolant supply hole 54. Reference numeral 55 indicates a chip supply hole for supplying the coolant from the coolant supply hole 54 to each of the cutting edge chips 71, 81, 91.

The reamer 60 has a shank portion 61 and a cutting edge portion 62, and a finishing blade 63 is formed at the tip of the cutting edge portion 62.

By the way, the valve guide 30 has a diameter of 7
Holes having a depth more than double must be machined, and such hole machining is generally called deep hole machining. In order to secure a predetermined surface roughness and a long life of the reamer 60 in deep hole machining, it is necessary to provide a coolant-through type mechanism for passing the coolant inside the reamer 60 and supply sufficient coolant to the cutting edge. In the coolant through type, it is necessary to make a hole inside the reamer 60, and from the viewpoint of securing the rigidity of the reamer 60 and reducing the cost, a configuration is adopted in which the coolant is not supplied to the parts other than the finishing blade 63. Tend to be.

However, if the coolant is not sufficiently supplied also to the back taper portion located at the rear portion of the finishing blade 63, the chips between the inner peripheral surface of the valve guide hole 31 and the outer peripheral surface of the reamer 60 near the back taper portion. There is a risk that biting may occur and the surface roughness may be deteriorated.

In view of this point, the present embodiment is configured as follows. As shown in FIG. 3 (B), the reamer 6
At 0, a central hole 64 communicating with the coolant supply hole 54 is formed along the rotation axis X. The coolant guided through the center hole 64 is supplied toward the finishing blade 63 from the hole opened on the outer peripheral surface of the cutting edge portion 62. In addition to the center hole 64 for coolant through, a coolant supply groove 65 extending from the base end of the shank portion 61 to the tip of the cutting blade portion 62 is formed on the outer peripheral surface of the reamer 60. The coolant guided through the coolant supply groove 65 is also supplied toward the finishing blade 63.

When the coolant is supplied to the finishing blade 63 through the coolant supply groove 65 in this way, the center hole 6
The inner diameter of 4 can be set to the minimum size, and the rigidity of the reamer 60 can be increased. Coolant supply groove 6
It goes without saying that the center hole 64 need not be formed if the required amount of coolant can be secured with only five.
In this case, by eliminating the center hole 64, the rigidity of the reamer 60 can be further increased even with the same outer diameter, and the reamer 60 itself can be easily manufactured.

Next, the operation of this embodiment will be described. First, referring to FIGS. 7 (A) and (B) and FIGS. 8 (A) and (B), the first to third cutting edge portions 70, 80, 90 are attached to the tool body 50.
I will explain the setting work to be attached to.

(1) As shown in FIG. 7A, the horizontal reference line 124, the vertical reference line 125, the first valve seat surface 21.
Forming the first reference line 121 and the second valve seat surface 22
The second reference line 122 and the third valve seat surface 23 that configure the
The drawing which drew the 3rd reference line 123 which comprises is created.
The horizontal reference line 124 and the vertical reference line 125 pass through the intersection 126 of the second reference line 122 and the third reference line 123. The drawing at this time is created with the median of dimensional tolerances. A reference piece is manufactured based on the created drawing.

(2) The horizontal and vertical reference lines of the presetter, which is a machine for setting the tool, are the same as the reference piece manufactured in (1).
Set so that they match.

(3) The tool body 50 is so arranged that the line passing through the center of the tool body 50 is parallel to the horizontal reference line 124 of the reference piece.
After setting, set the presetter with the valve seat diameter φD1. As a result, the position of the horizontal reference line 124 coincides with the position of the valve seat diameter φD1.

(4) Third cutting edge tip 9 which is a fixed tip
1 is attached to the tool body 50. As shown in FIG. 7B, the tool body 50 is moved in the longitudinal direction so that the intersection 126 and the cutting edge of the third cutting edge tip 91 coincide with each other. Since the third cutting edge tip 91 is a fixed type, it may not coincide with the third reference line 123 depending on the manufacturing accuracy of the tool, but the manufacturing accuracy of the tool is sufficiently smaller than the illustrated tolerance, so that no problem occurs.

(5) Next, as shown in FIG. 8A, the cutting edge of the second cutting edge tip 81, which is a fine adjustment tip, is aligned with the second reference line 122 of the reference piece. Specifically, with the cartridge clamp screw 85 temporarily tightened, the angle adjusting screw 112 is rotated to rotate or elastically deform the second cartridge 82 with the cartridge clamp screw 85 as a fulcrum, thereby rotating the rotation axis X and the second cutting edge. The angle formed by the tip 81 is adjusted to the angle θ2. After adjusting the angle, adjust screw 101
Is rotated to move the second cartridge 82 in the longitudinal direction to adjust the position, and the cutting blade of the second cutting blade tip 81 is moved to the second reference line 1.
Set to 22. As a result, the second cutting edge tip 81 is set and the valve seat diameter φD1 is determined.

(6) Next, as shown in FIG. 8B, the cutting edge of the first cutting edge tip 71, which is a fine adjustment tip, is aligned with the first reference line 121 of the reference piece. Specifically, similarly to (5) above, the angle adjusting screw 112 is turned to adjust the angle formed by the rotation axis X and the first cutting edge tip 71 to the angle θ1, and the adjusting screw 101 is turned to rotate the first cartridge. Adjust the longitudinal position of 72. As a result, the first cutting edge tip 71 is set and the valve seat width W is determined.

By the series of operations described above, the setting operation of the first to third cutting edge portions 70, 80, 90 is completed. The setting work may be performed using a film or a projector based on the created drawing.

The first to third cutting edge chips 71, 81, 91
It is also possible to use all of the movable cutting tips as movable tips, but as in the present embodiment, the third cutting edge tip 91 is fixed and the first and second cutting edge tips 71 and 81 are adjustable. This has the following five advantages.

First, it is difficult to set a standard when all the cutting edge tips are of the adjustable moving type, but when one third cutting edge tip 91 is fixed, the fixed third cutting edge tip 91 is fixed.
Can be used as a reference when setting the other cutting blade tips 71, 81, and there is an advantage that the other cutting blade tips 71, 81 can be easily adjusted.

Third cutting edge tip 9 fixed as described above
1 shifts from the third reference line 123 by an error in manufacturing, but this shift can be grasped in advance at the chip manufacturing stage. Therefore, by correcting the deviation and attaching the third cutting edge tip 91,
The cutting blade tip 91 can be used as a reference when setting the other fine adjustment tips 71 and 81.

Further, although the setting operation is repeated, by providing a fixed type tip that serves as a setting reference, it becomes possible to set all the cutting edge tips 71, 81 and 91 with the same accuracy every time.

Secondly, there is an advantage that a work mistake at the time of tool setting can be confirmed.

For example, it is assumed that a setting error has occurred in the above procedure (3). This setting error means that when the tool body 50 is set in the presetter,
A state in which the tool body 50 has an abnormality such as inclination. When the tool body 50 is attached to the presetter, no inclination or the like should occur. However, in this type of hole drilling tool 40, even if the inclination is such that a normal tool does not hinder the inclination of the cutting edge. As a result of being added to the inclination, there is a possibility that a predetermined processing accuracy cannot be secured.

If all the cutting tips are movable,
Even if the tool body 50 is tilted when the tool body 50 is set on the presetter, this cannot be recognized, and the setting operation is continued with the above setting error. As a result, the valve seat surfaces 21-23
Angle deviates from the target angle, and machining NG occurs.

On the other hand, when one cutting blade tip is fixed, the inclination of the fixed third cutting blade tip 91 with respect to the center line of the presetter is examined, and the deviation amount due to manufacturing error and the deviation amount at the time of setting are set. By comparing with, it is possible to easily determine whether or not the above setting error has occurred. As described above, since it is possible to easily determine whether or not the state when the tool body 50 is attached to the presetter is abnormal, it is possible to easily and quickly confirm a work mistake at the time of tool setting, and as a result, a work mistake in the setting work. Can be prevented.

Thirdly, there is an advantage that the setting time required for adjustment for ensuring a predetermined accuracy can be reduced.

Fourth, since the cartridge is unnecessary in the case of the fixed type tip,
There is an advantage that the space of the cutting edge portion 90 can be reduced and the rigidity of the tool body 50 can be improved. In addition to this, the valve seat diameter φD1 at the lower limit of production can be set to, for example, φ15 mm.

Fifth, since the other two cutting edge tips 71 and 81 are set with the third cutting edge tip 91 of the fixed type tip as a reference, the position of the cutting edge along the rotation axis X does not change significantly. As a result, there is little change in the positional relationship between each cutting blade tip 71, 81, 91 and the chip supply hole 55, and sufficient coolant is supplied to each cutting blade tip 71, 81, 91 for a stable chip life. There is an advantage that can be secured. If all the cutting blade tips are of the adjustable moving type, the positional relationship between each cutting blade tip and the chip supply hole 55 may be significantly deviated, and there is a risk that the coolant supply to the cutting blade tips will be insufficient.

Although it is conceivable that all the cutting blade tips are fixed, in this case, a pocket for fixing each cutting blade tip must be formed in the tool body 50. However, the engraving accuracy of the pocket is ± 0.
01mm is the limit, and the chip manufacturing accuracy is ± 0.01
Since mm is the limit, the accuracy required for the valve seat surface as a product cannot be satisfied.

It is also conceivable that the cutting blades forming the valve seat surfaces of a plurality of stages are machined by one integrally formed cutting blade tip, but considering the necessity of re-polishing and the life of the cutting blade tip. It is very expensive and cannot be practically adopted. On the other hand, since the cutting blade tips 71, 81, 91 of the present embodiment are of the throw-away type, it is possible to suppress an increase in cost, and moreover, despite using a plurality of cutting blade tips 71, 81, 91. No
Each of the valve seat surfaces 21, 22, and 23 in a plurality of stages can be processed with high accuracy.

Next, the procedure for processing the valve seat surfaces 21, 22, 23 and the valve guide hole 31 will be described.

First, as shown in FIG. 9, the opening on the valve seat 20 side of the valve guide 30 is counterbored with a counterboring tool (not shown).

The reason for carrying out the counterbore processing is to ensure the accuracy of valve seat surface runout with respect to the valve guide hole 31. Since the valve guide 30 is made of a sintered material, the accuracy of the prepared hole 32 is not so good. Therefore, when performing bushing processing without installing a bush for preventing bending of the reamer 60 at the mouth of the valve guide 30, the reamer 60 is set to φd of the valve guide 30 when finishing processing to make the inner diameter of the valve guide 30 φD2. It bends following the prepared hole 32. Therefore, the valve guide hole itself is bent, and the runout accuracy of each valve seat surface 21, 22, 23 based on the valve guide hole cannot satisfy the required value.

Therefore, in the present embodiment, in order to reduce the bending of the valve guide hole 31, a diameter around the rotation axis X of the hole drilling tool 40 is provided at the mouth of the valve guide 30 which is the machining start point of the reamer 60. φd1 (φD2>φd1> φ
d), a spot facing 33 having a depth L is formed. As the counter boring tool, an end mill that does not follow the prepared hole 32 of the valve guide 30 or a tool equivalent thereto is used. The counterbore processing tool has its tip end directed toward the inner side of the hole, and the rotation axis X of the tool is set to the valve guide 30 and the valve seat 20.
It is attached to the drive shaft of a machine tool such as a machining center so that it is coaxial with the center line. Then, when the formation of the counterbore 33 on which the spot boring is to be performed is completed by rotating the bobbin cutting tool around the rotation axis X and advancing it toward the tip side, the spot boring tool is opened. The boring tool 40 of the present embodiment is moved backward by removing the counter boring tool from the drive shaft by the ATC of the machining center.
Replace with. The hole drilling tool 40 is attached to the drive shaft via the arbor portion with the tip end portion thereof facing the inner side of the hole, the rotation axis X being coaxial with the center lines of the valve guide 30 and the valve seat 20. Then, while the hole drilling tool 40 is rotated around the rotation axis X, the hole drilling tool 40 is fed toward the tip side to be advanced.

Then, the tip of the reamer 60 is attached to the reamer 6
The counterbore 33 is machined so as to follow the counterbore 33 having an inner diameter φd1 which is slightly smaller than the diameter of 0, and the reamer 60 follows the centerline of the machined counterbore 33, that is, the rotation axis X of the hole machining tool 40. While moving forward so as to be guided by the valve guide hole 31 of the valve guide 30 having an inner diameter φD2.
Finish processing. At this time, the processed spot facing 3
3 exhibits a function as a bush that enhances the straightness of the reamer 60, and has a working mode in which the reamer 60 is sequentially guided along the rotation axis line X. Therefore, the center line of the finished valve guide hole 31 and the rotation axis X of the hole machining tool 40 are coaxial.

When finishing the valve guide hole 31,
The coolant supplied from a facility (not shown) is supplied to the base end of the reamer 60 through the coolant supply hole 54 and toward the finishing blade 63 through the center hole 64. Further, the coolant is discharged from the coolant supply groove 65 to the outside of the reamer 60, and the discharged coolant is guided through the coolant supply groove 65 and is supplied toward the finishing blade 63.

Since the reamer 60 advances while using the valve guide hole 31 as a guide, it is necessary to cool the entire cutting edge. In the present embodiment, the coolant flows along the coolant supply groove 65 extending from the base end of the shank portion 61 to the tip of the cutting edge portion 62, so that the coolant easily permeates the entire finishing blade 63 and the central hole 64. The entire cutting edge can be cooled more efficiently than in the case where the coolant is supplied only through. As a result, it is possible to suppress the problem of plucked surface roughness due to galling of the finishing blade 63 and wear of the finishing blade 63, and the machining accuracy of the valve guide hole machining is stabilized.

FIG. 10 is a diagram showing how the presence or absence of the coolant supply groove 65 affects the surface roughness of the valve guide hole 31. In the figure, the white circles indicate the case of the present embodiment in which the coolant supply groove 65 is formed, and the black circles indicate the case in which the coolant supply groove 65 is not formed, in contrast.

As shown in the figure, when the coolant supply groove 65 is not formed, the cutting speed (m / min)
If the speed is increased, the accuracy required for the surface roughness of the valve guide hole 31 cannot be satisfied, but in the case of the present embodiment in which the coolant supply groove 65 is formed, even if the cutting speed (m / min) is increased ( V4 and V5), the accuracy required for the surface roughness of the valve guide hole 31 can be satisfied,
It was confirmed that forming the coolant supply groove 65 improves the machining accuracy of the valve guide hole machining.

When the hole drilling tool 40 is further advanced, the first to third cutting blade tips 71, 81, 91 reach the valve seat 20, and the first to third three-stage valve seat surfaces 2 are provided.
1, 22, 23 are formed at the same time. That is, the tilt angle θ1 is located at the inner side of the hole and with respect to the rotation axis X.
The first valve seat surface 21, which is inclined at, is the first cutting edge tip 7
1 and is located in the middle and has an axis of rotation X
The second valve seat surface 22 that is inclined at an inclination angle θ2 is formed by the second cutting edge tip 81, is located on the opening edge side, and is inclined at an inclination angle θ with respect to the rotation axis X.
The third valve seat surface 23 inclined at 3 is formed by the third cutting edge tip 91.

When forming the valve seat surfaces 21, 22, 23, since the center line of the valve guide hole 31 is coaxial with the rotation axis X of the hole machining tool 40, the valve seat surfaces 21, 22, The coaxiality between 23 and the valve guide hole 31 is ensured, and as a result, the surface runout of the valve seat surfaces 21, 22, 23 with reference to the valve guide hole 31 satisfies a predetermined dimensional tolerance.

11 and 12 show the valve guide 30.
FIG. 11 is a diagram showing an effect of performing a spot facing process on the mouth of FIG.
Is a diagram showing the influence of the diameter of the counterbore 33 of the valve guide 30 on the surface runout accuracy of the valve seat surfaces 21, 22, 23. FIG. 12 shows the depth of the counterbore 33 of the valve guide 30 when the depth of the valve seat 30 is small. It is a figure which shows the influence which it has on the surface runout accuracy of the surfaces 21, 22, and 23.

As shown in the drawing, the inner diameter φd1 of the counterbore 33 is
It was confirmed that the surface runout accuracy of the valve seat surfaces 21, 22, 23 was improved by increasing the value of L and increasing the depth L.

As described above, in the present embodiment, the reamer 60 is of a fixed type and the valve seat surface 2 having a plurality of stages is used.
Since all 1, 22, and 23 are formed at the same time, the hole drilling tool 40 is not provided with a mechanism for sliding the cutting blade tip during the drilling or a mechanism for moving the reamer 60 back and forth. Therefore, the structure of the hole drilling tool 40 itself is simplified, and the tool cost can be reduced.
Further, since the setting of the position and the inclination angle of each cutting edge tip 71, 81, 91 is completed before the hole machining, compared to a tool that moves the cutting edge tip in the middle of the hole machining, the hole with higher accuracy is required. Machining can be performed, and the time required for adjustment for ensuring a predetermined accuracy can be shortened.

The cutting blade tips 71, 81, 9 are formed during the drilling process.
Since it is not necessary to move the reamer 1 and the reamer 60 back and forth with respect to the tool body 50, the cutting blade tip 71,
It is not necessary to provide a dedicated drive shaft for advancing / retreating 81, 91 or the reamer 60. Further, the counterbore processing is performed by the reamer 60 so as to follow the counterbore 33 which is slightly smaller than the diameter of the reamer 60.
However, it has the function of a bush that enhances the straightness of the reamer 60. Therefore, without using a dedicated machine tool provided with a dedicated drive shaft and a dedicated bush for preventing bending of the reamer 60, a machine tool such as a general-purpose machining center finishes the valve guide hole 31. It is possible to form each valve seat surface 21, 22, 23. The hole drilling that can be performed by using a general-purpose machine tool in this way meets the recent demand that a flexible production line must be constructed, and can contribute to the reduction of manufacturing costs. In particular,
When a machining center is used as a general-purpose machine tool, it is possible to perform hole drilling continuously after machining other parts of the cylinder head 10, and a series of machining can be efficiently performed.

When the valve seat surfaces of a plurality of stages are divided and formed using a plurality of tools, an error is likely to occur in the processing position and the processing depth between the tools, and as a result, the width of each valve seat surface and the The accuracy of the inner diameter may not be stable. On the other hand, in the present embodiment, with one hole drilling tool 40,
Since all of the first to third valve seat surfaces 21, 22, 23 are formed at the same time, high coaxiality can be easily ensured, and the finished valve seat surfaces 21, 2
It is possible to give the moldings 2 and 23 a higher molding precision than the processing by the conventional dedicated machine.

Moreover, since the counterbore 33 coaxial with the rotation axis X of the hole drilling tool 40 is formed in advance at the mouth of the valve guide 30, the reamer 60 is used by the reamer 60.
Reamer 60 that prevents bending in accordance with
Can be given to. Therefore, the coaxiality between the center line of the valve guide hole 31 and the center line of each valve seat surface 21, 22, 23 can be surely ensured, and the valve guide hole 31 and each valve seat surface 21, 22, 23
In addition, higher molding accuracy can be provided.

As described above, according to this embodiment, the precision required for the surface roughness, the hole diameter, and the roundness of the valve guide hole 31 can be satisfied, and the surface of each valve seat surface 21, 22, 23 is satisfied. The accuracy required for the angle, the surface width, the diameter, and the surface roughness can be satisfied, and further, the accuracy required for the deflection of the valve seat surface with respect to the valve guide hole 31 can be satisfied.

(Other Embodiments) Each valve seat surface 21,
22 and 23 are rough machining steps using a tool not shown,
It may be formed through two steps including a finishing step using the hole drilling tool 40. If the rough machining of the valve seat surface is performed simultaneously with the counterbore machining of the valve guide 30, the machining time can be shortened. By roughing the valve seat 20, it is possible to reduce the finishing stock and to stabilize the stocking. As a result, the machining accuracy of the valve seat surfaces 21, 22, 23 is stable for a long time.

As shown in FIG. 13, the reamer 60a
A blade portion 66 corresponding to an end mill having a diameter smaller than the diameter of the reamer may be further provided at the tip portion of the. The end mill blade portion 66 at the tip is the pilot hole 32 of the valve guide 30.
Since it is difficult to follow the above, it is possible to obtain the same effect as in the case of processing the spot facing 33. In the hole drilling tool having such a reamer 60a, the valve seat surface runout accuracy with respect to the valve guide hole 31 can be secured even if the counterbore processing of the valve guide 30 is eliminated.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a cylinder head in which a valve seat surface and a valve guide hole are formed.

FIG. 2 is a schematic configuration diagram showing a hole drilling tool according to an embodiment of the present invention.

3 (A) and 3 (B) are respectively 3A of FIG.
It is sectional drawing which follows the -3A line and the 3B-3B line.

4 is a perspective view showing a first cutting edge portion shown in FIG. 2. FIG.

5 (A) and (B) are views provided for explaining a work for adjusting a position and an inclination angle of a first cutting edge tip.

FIG. 6 is a diagram showing a rotation locus of the first, second, and third cutting blade tips about a rotation axis and first, second, and third valve seat surfaces formed by these cutting blade tips. Is.

7 (A) and (B) are views for explaining a setting operation for attaching the first to third cutting edge parts to the tool body.

FIGS. 8A and 8B are views for explaining a setting operation for attaching the first to third cutting edge parts to the tool body.

FIG. 9 is a cross-sectional view showing a valve guide in which a spot facing is formed at the mouth of the valve seat side.

FIG. 10 is a diagram showing how the presence or absence of a coolant supply groove affects the surface roughness of a valve guide hole.

FIG. 11 is a diagram showing the influence of the diameter of the counterbore of the valve guide on the surface runout accuracy of the valve seat surface.

FIG. 12 is a diagram showing the influence of the depth of the counterbore of the valve guide on the surface runout accuracy of the valve seat surface.

FIG. 13 is a view showing a reamer having an end mill blade portion provided at its tip.

[Explanation of symbols]

10 ... Cylinder head (workpiece) 20 ... Valve seat (machining hole) 21, 22, 23 ... First, second and third valve seat surfaces (machining surface) 30 ... Valve guide 31 ... Valve guide hole (machining) Hole 33) Counterbore 40 Hole machining tool 50 Tool body 60, 60a Reamer 63 Finishing blade (cutting edge) 65 Coolant supply groove 66 End mill blades 70, 80, 90 First, second , Third cutting edge parts 71, 81, 91 ... First, second and third cutting edge tips 72, 82 ... First and second cartridges 75, 85 ... Cartridge clamp screw 100 ... Longitudinal direction adjusting means 101 ... adjusting screw 110 ... angle adjusting means 111 ... screw hole 112 ... angle adjusting screw X ... rotation axis

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Inomata             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Shinji Yukinari             2-18-1, Kamihito, Hirano-ku, Osaka-shi, Osaka               Daiji Et Industries Co., Ltd. F-term (reference) 3C036 AA22 BB06 KK03                 3C037 EE05                 3C046 AA08 KK02 LL00 NN07 PP03

Claims (6)

[Claims] 1. A hole drilling tool having a plurality of cutting edges, each of which has a plurality of step faces having different inclination angles with respect to the axis of the hole to be formed in the opening of the hole formed in the workpiece, and a rotary axis of the hole drilling tool. In a hole drilling method of rotating and driving around, one cutting edge tip among a plurality of cutting edge tips forming each of the machining surfaces is fixedly attached, and another cutting edge tip is attached to the one cutting edge. A hole drilling method, wherein all of the plurality of stages of machined surfaces are formed at the same time by using a hole drilling tool attached so that the position and angle along the rotation axis with respect to the blade tip can be adjusted relatively. 2. A hole drilling tool having a plurality of cutting blade tips each forming a plurality of step faces having different inclination angles with respect to the axis of the hole at the opening of the hole formed in the workpiece, One of the plurality of cutting blade tips is fixedly attached to the tool body that is rotationally driven around the rotation axis, and the other cutting blade tip is rotated with respect to the fixed one cutting blade tip. A hole drilling tool, characterized in that it is attached to the tool body so that the position and angle along the axis can be relatively adjusted, and that all of the plurality of steps of the machining surface are simultaneously formed by the plurality of cutting blade tips. 3. The hole drilling tool according to claim 2, wherein a reamer for finishing the inner peripheral surface of the drilled hole is attached to the tip of the tool body along the rotation axis. 4. The hole drilling tool according to claim 3, wherein the reamer finishes an inner peripheral surface of a drilled hole that has been previously machined. 5. The hole drilling tool according to claim 3, wherein the reamer is provided with an end mill blade portion having a diameter smaller than a diameter of the reamer at a tip portion thereof. 6. The hole drilling tool according to claim 3, wherein the reamer has a coolant supply groove for supplying a coolant to a cutting edge provided at a tip end portion, which is formed on an outer peripheral surface of the reamer.