JP5271867B2 - Drilling tool and drilling method - Google Patents

Description

  The present invention relates to a drilling tool and a drilling method for forming a hole for press-fitting a valve seat and a valve guide of an intake valve or an exhaust valve of an engine cylinder head. Specifically, the present invention relates to a drilling tool and a drilling method capable of reducing the investment cost of equipment and reducing the drilling processing time.

  Conventionally, a valve guide that holds the shaft of an intake valve or an exhaust valve of a cylinder head of an engine and a valve seat that is a valve seat of the intake valve or the exhaust valve are press-fitted into the cylinder head. For this reason, using a dedicated drilling tool (see, for example, Patent Document 1), a hole into which a valve seat is press-fitted (hereinafter referred to as a valve seat press-fitting hole) and a hole into which a valve guide is press-fitted (hereinafter referred to as a valve) And a counterbore (dish shape) hole for guiding the press-fitted valve guide into the valve guide press-fitting hole (hereinafter referred to as a valve guide opening counterbore) is formed in the cylinder head. The

JP 2005-305581 A

However, the processing of the valve seat press-fitting hole and the valve guide press-fitting hole is required to have high accuracy, particularly high roundness. On the other hand, the machining of the valve guide mouth counterbore does not require high accuracy, but has a large radial resistance. Radial resistance is the resistance applied to the drilling tool by the radial load received from the workpiece (cylinder head) when the blade provided radially on the drilling tool contacts the workpiece (cylinder head). Say.
For this reason, the processing of the valve seat press-fitting hole and the valve guide press-fitting hole is a separate process from the processing of the valve guide mouth counterbore so as not to be adversely affected by self-excited vibration caused by the processing of the valve guide mouthbore having a large radial resistance. Done. That is, when the conventional drilling tool is used, the first step for forming the valve guide opening counterbore and the second step for forming the valve seat press-fitting hole and the valve guide press-fitting hole are separately required. .
For this reason, when the conventional drilling tool is used, the investment cost of the whole equipment increases and the processing time becomes long.

  The present invention relates to a drilling tool and a drilling method for forming a hole for press-fitting a valve seat and a valve guide of an intake valve or an exhaust valve of an engine cylinder head, which reduces the investment cost of equipment, and An object of the present invention is to provide a drilling tool and a drilling method capable of shortening the processing time.

  The drilling tool of the present invention (for example, the drilling tool 21 in the embodiment) is a hole into which a valve seat and a valve guide of an intake valve or an exhaust valve of an engine cylinder head (for example, the cylinder head 1 in the embodiment) are press-fitted. A valve seat press-fitting tool for forming a valve seat press-fitting hole (for example, a valve seat press-fitting hole 11 in the embodiment) into which the valve seat is press-fitted. A valve guide that forms a hole processing blade (for example, a valve seat press-fitting hole processing blade 33 in the embodiment) and a valve guide press-fitting hole (for example, a valve guide press-fitting hole 13 in the embodiment) into which the valve guide is pressed. Cutting tool for press-fitting hole (for example, valve guide press-fitting hole in the embodiment) A valve guide opening counterbore for forming a work tool 31) and a valve guide opening counterbore (for example, the valve guide opening counterbore 12 in the embodiment) for guiding the press-fitted valve guide into the valve guide press-fitting hole. A drilling tool provided with a cutting tool (for example, the valve guide opening counterbore cutting tool 32 in the embodiment), wherein the valve guide opening counterbore cutting tool is a blade of the valve seat press-fitting hole cutting blade It has two blades (for example, blades 32a and 32b in the embodiment) that are arranged so as to have different phases during rotation and that make point contact with the workpiece.

  According to this invention, the valve guide opening counterbore cutting tool has the following first to third characteristics. The first feature is that it has a blade that makes point contact with the workpiece. The second feature is that it has two blades that have a smaller number of blades than the conventional one. The third feature is that the phase during rotation of these two blades is different from the phase during rotation of the blade of the valve seat press-fitting hole cutting tool. According to the third feature, the degree of influence of the radial resistance applied when machining the valve guide opening counterbore to the machining of the valve seat press-fitting hole by the valve seat press-fitting hole cutting tool, that is, the magnitude of self-excited vibration was in phase. Reduced compared to the case. Further, since the radial resistance itself at the time of counterbore machining of the valve guide is reduced from the first feature and the second feature, the degree of influence, that is, the magnitude of self-excited vibration is further reduced. Thereby, the accuracy of the valve seat press-fitting hole, particularly the roundness can be ensured with high accuracy. Therefore, it becomes feasible to process the valve seat press-fitting hole, the valve guide opening counterbore, and the valve guide press-fitting hole in one step. As a result, it is possible to reduce the investment cost of the equipment and shorten the processing time as compared with the case where the conventional processing is performed in two steps.

  In this case, the valve guide mouth counterbore cutting tool may have a bite blade shape so as to make point contact with the workpiece.

  In this case, the blade of the valve seat press-fitting hole processing blade and the valve guide press-fitting hole cutting tool may be arranged so as to be in phase with each other during rotation.

  In the drilling method of the present invention, a hole into which a valve seat and a valve guide of an intake valve or an exhaust valve of an engine cylinder head (for example, the cylinder head 1 in the embodiment) is press-fitted is formed in the cylinder header which is a workpiece. A punching tool (for example, a punching tool 21 in the embodiment), and a valve seat press-fitting for forming a valve seat press-fitting hole (for example, a valve seat press-fitting hole 11 in the embodiment) into which the valve seat is press-fitted. A valve guide that forms a hole processing blade (for example, a valve seat press-fitting hole processing blade 33 in the embodiment) and a valve guide press-fitting hole (for example, a valve guide press-fitting hole 13 in the embodiment) into which the valve guide is pressed. Cutting tool for press-fitting hole (for example, valve guide press-fitting hole in the embodiment) In order to form a valve guide opening counterbore (for example, a valve guide opening counterbore 12 in the embodiment) for guiding the valve guide 31) and the valve guide to be press-fitted into the valve guide press-fitting hole in the workpiece, the valve The valve guide mouth having two blades (for example, the blades 32a and 32b in the embodiment) which are arranged so as to be in a phase different from that of the blade of the sheet press-fitting hole cutting tool and are in point contact with the workpiece. By performing only one step of inserting a drilling tool provided with a counterbore cutting tool (for example, the valve guide mouth counterbore cutter 32 in the embodiment) with respect to the workpiece, the valve seat Forming a press-fitting hole, the valve guide press-fitting hole, and the valve guide opening counterbore on the workpiece; And features.

  According to this invention, a drilling tool provided with a valve guide mouth counterbore cutting tool having the following first to third features is used. The first feature is that it has a blade that makes point contact with the workpiece. The second feature is that it has two blades that have a smaller number of blades than the conventional one. The third feature is that the phase during rotation of these two blades is different from the phase during rotation of the blade of the valve seat press-fitting hole cutting tool. According to the third feature, the degree of influence of the radial resistance applied when machining the valve guide opening counterbore to the machining of the valve seat press-fitting hole by the valve seat press-fitting hole cutting tool, that is, the magnitude of self-excited vibration was in phase. Reduced compared to the case. Furthermore, since the radial resistance itself applied when the valve guide opening counterbore is processed becomes smaller than the first feature and the second feature, the degree of influence, that is, the magnitude of self-excited vibration is further reduced. Thereby, even if the valve seat press-fitting hole, the valve guide opening counterbore, and the valve guide press-fitting hole are processed in one step, the accuracy of the valve seat press-fitting hole, in particular, the roundness can be ensured with high accuracy. That is, processing in one process, which has been difficult to realize in the past, can be easily performed. As a result, it is possible to reduce the investment cost of the equipment and shorten the processing time as compared with the case where the conventional processing is performed in two steps.

  According to the present invention, the radial resistance applied when processing the valve guide opening counterbore is reduced, and the degree of influence of the radial resistance applied when processing the valve guide opening counterbore on the valve seat press-fitting hole processing by the valve seat press-fitting hole cutting tool, That is, the magnitude of self-excited vibration is also reduced. Thereby, the accuracy of the valve seat press-fitting hole, particularly the roundness can be ensured with high accuracy. Therefore, it becomes feasible to process the valve seat press-fitting hole, the valve guide opening counterbore, and the valve guide press-fitting hole in one step. As a result, it is possible to reduce the investment cost of the equipment and shorten the processing time as compared with the case where the conventional processing is performed in two steps.

It is a top view which shows the general | schematic external appearance structure of the cylinder head in which the valve seat press-fit hole etc. were formed by the process of the drilling tool which concerns on one Embodiment of this invention. It is sectional drawing which shows schematic structure of the valve seat press-fitting hole, valve guide opening counterbore, and valve guide press-fitting hole which were formed in the cylinder head with the drilling tool which concerns on one Embodiment of this invention. It is a perspective view which shows schematic structure of the drilling tool which concerns on one Embodiment of this invention. It is a figure explaining the shape of the blade of the valve guide opening counterbore cutting tool of FIG. 3, Comprising: The enlarged view of the contact part of a blade and a workpiece | work is shown. It is a figure explaining the number of the blades of the valve guide mouth counterbore cutting tool of Drawing 3, and is a sectional view of the radial direction. It is a figure explaining the relationship of the phase with respect to the blade of the blade of the valve guide opening counterbore processing tool of FIG. 3 with respect to the blade of the valve seat press-fit hole processing, Comprising: The radial direction sectional drawing is shown.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a top view showing a schematic external configuration of a cylinder head 1 in which a valve seat press-fitting hole 11 and the like are formed by processing a drilling tool according to an embodiment of the present invention.
FIG. 2 shows a valve seat press-fitting hole 11, a valve guide opening counterbore 12, and a valve guide press-fitting hole 13 formed in the cylinder head 1 by machining a drilling tool according to an embodiment of the present invention. It is sectional drawing which shows schematic structure.
By the drilling tool according to the embodiment of the present invention, the surface of the cylinder head 1 is directed from the surface to the inside (from the top to the bottom in FIG. 2) around the line XX ′ in FIG. The valve seat press-fitting hole 11, the valve guide opening counterbore 12, and the valve guide press-fitting hole 13 are formed concentrically in that order.
An intake valve or an exhaust valve pipe (not shown) is disposed in a region indicated by a thin line in FIG. 2 between the valve seat press-fitting hole 11 and the valve guide opening counterbore 12. For this reason, as shown in FIG. 2, the depth of the counterbore 12 at the valve guide opening is not uniform, but varies depending on the arrangement position of the pipe.

FIG. 3 is a perspective view showing a schematic configuration of the drilling tool 21 according to one embodiment of the present invention.
Hereinafter, a processing target of the drilling tool 21, that is, a target on which the valve seat press-fitting hole 11, the valve guide opening counterbore 12, and the valve guide press-fitting hole 13 are formed is referred to as a workpiece. In the present embodiment, the cylinder head 1 is a workpiece.
In order to be able to rotate around the axis indicated by the line AA ′ in FIG. 3, the drilling tool 21 includes a valve guide press-fitting hole cutting tool 31 and a valve guide opening in order from the left end in FIG. 3. A counterbore cutting tool 32, a valve seat press-fitting hole cutting tool 33, and a base end 34 are provided concentrically.

  The blade 31 for valve guide press-fitting hole processing is uniformly formed with four blades 31a to 31d in a radial direction from the shaft. In FIG. 3, the valve guide press-fitting hole processing blade tool 31 corresponds to a region through which a line connecting the axis passes from each point marked with reference numerals 31 a to 31 d on the circumference of the first dotted line from the left. Blades 31a to 31d are formed. Each of these four blades 31a to 31d is formed in a spiral shape in the axial direction. The length in the radial direction from the shaft to each of the blades 31a to 31d substantially matches the radius of the valve guide press-fitting hole 13, and the length in the axial direction of the valve guide press-fitting hole cutting tool 31 is the valve guide press-fitting hole. It is almost coincident with the depth of 13. Accordingly, the valve guide press-fitting hole cutting tool 31 formed with such four blades 31a to 31d is rotated about the axis while being inserted into the work, so that the valve guide press-fitting hole 13 is moved into the work. Formed.

  The blade 33 for valve seat press-fitting hole processing is uniformly formed with four blades 33a to 33d in a radial direction from the shaft. In FIG. 3, the valve seat press-fitting hole cutting tool 33 corresponds to a region through which a line connecting an axis passes from each point indicated by reference numerals 33 a to 33 d on the circumference of the third dotted line from the left. Blades 33a to 33d are formed. Each of the four blades 33a to 33d is formed in a spiral shape in the axial direction. The radial length from the shaft to each of the blades 33a to 33d is substantially the same as the radius of the valve seat press-fitting hole 11, and the axial length of the valve seat press-fitting hole cutting tool 33 is the valve seat press-fitting hole. This is almost the same as the depth of 11. Therefore, the valve seat press-fitting hole cutting tool 33 in which the four blades 33a to 33d are formed is rotated about the axis while being inserted into the work, so that the valve seat press-fitting hole 11 is moved into the work. Formed.

  In the valve guide mouth counterbore cutting tool 32, two blades are radially formed in a radial direction from the shaft. In FIG. 3, the valve guide mouth counterbore cutting tool 32 corresponds to a region through which a line connecting the axis passes from each point marked with reference numerals 32 a and 32 b on the circumference of the second dotted line from the left. Blades 32a and 32b are formed. Each of these two blades 32a and 32b is formed in a spiral shape in the axial direction. The length in the radial direction from the shaft to each of the blades 32a and 32b substantially coincides with the radius of the counterbore 12 at the valve guide opening, and the length in the axial direction of the counterbore cutting tool 32 at the valve guide opening is the valve guide opening counterbore. It almost coincides with the deepest depth of 12. Therefore, the valve guide mouth counterbore 12 having such two blades 32a and 32b is rotated about the axis while being inserted into the work, so that the valve guide mouth counterbore 12 is moved into the work. Formed.

  The valve guide opening counterbore cutting tool 32 has the following first to third characteristics. The first feature is that it has blades 32a and 32b that are in point contact with the workpiece due to the bite blade shape. The second feature is that it has two blades 32a and 32b, which has a smaller number of blades than the conventional one. The third feature is that the phase during rotation of each of the two blades 32a and 32b is different from the phase during rotation of each of the four blades 33a to 33d of the blade 33 for valve seat press-fitting hole processing. Is a point. Here, the phase refers to the rotational position of the blade during rotation in the radial cross section. Hereinafter, the first to third features will be described in detail.

FIG. 4 is a diagram for explaining the first feature. That is, FIG. 4 is a view for explaining the shape of the blade of the valve guide mouth counterbore cutting tool 32, and shows an enlarged view of the contact portion between the blade and the workpiece. 4a shows a conventional valve guide mouth counterbore cutting tool 51, and FIG. 4b shows a valve guide mouth counterbore tool 32 according to an embodiment of the present invention.
The blade 51a of the conventional valve guide mouth counterbore cutting tool 51 has a shape that is in line contact with the workpiece 61 as shown by the white arrow in FIG. 4a. For this reason, in the process with the conventional valve guide opening counterbore cutting tool 51, radial resistance is large.
On the other hand, the blade 32a (and the blade 32b shown in FIGS. 5 and 6) of the valve guide mouth counterbore cutting tool 32 according to the embodiment of the present invention is a workpiece as shown by the white arrow in FIG. 4b. It has a shape that makes point contact with 61, for example, a bite blade shape. For this reason, in the processing by the valve guide mouth counterbore cutting tool 32 according to the embodiment of the present invention, the contact area with the workpiece 61 is reduced as compared with the conventional one, and the radial resistance is reduced accordingly.

FIG. 5 is a diagram for explaining the second feature. That is, FIG. 5 is a diagram illustrating the number of blades of the valve guide mouth counterbore cutting tool 32, and shows a sectional view in the radial direction. 5a shows a conventional valve guide mouth counterbore cutting tool 51, and FIG. 5b shows a valve guide mouth counterbore tool 32 according to one embodiment of the present invention.
As shown in FIG. 5a, the conventional valve guide mouth counterbore cutting tool 51 has four blades 51a to 51d. On the other hand, the valve guide mouth counterbore cutting tool 32 according to the embodiment of the present invention has two blades 32a and 32b as shown in FIG. 5b. That is, the number of blades of the valve guide mouth counterbore cutting tool 32 according to the embodiment of the present invention is reduced as compared with the prior art. The reduction in the number of blades directly leads to a reduction in the contact area with respect to the workpiece 61, and the radial resistance applied during machining is reduced accordingly.

Next, the third feature will be described.
As shown in FIG. 3, the phase of the two blades 32a and 32b of the valve guide mouth counterbore cutting tool 32 is different from the phase of the four blades 33a to 33d of the valve seat press-fitting hole cutting tool 33. ing. For example, the phase difference between the blade 32b of the valve guide mouth counterbore cutting tool 32 and the blade 33b of the valve seat press-fitting hole cutting tool 33 is an angle θ.
FIG. 6 is a diagram for explaining the third feature. That is, FIG. 6 is a view for explaining the phase relationship during rotation between the blade of the valve guide mouth counterbore cutting tool 32 and the blade of the valve seat press-fitting hole cutting tool 33, and is a sectional view in the radial direction. Show. 6a shows a conventional valve guide mouth counterbore cutting tool 51, and FIG. 6b shows a valve guide mouth counterbore tool 32 according to an embodiment of the present invention.
In FIG. 6, the cross-sectional areas of all the cutting tools are the same for ease of explanation, but in actuality, they may be different as apparent from FIG. 6a, the conventional valve guide mouth counterbore cutting tool 51 (solid line portion) and the conventional valve seat press-fitting hole cutting blade 52 (dotted line portion) Although the images are drawn in a shifted state, the axes actually match.
Temporarily, a drilling tool (hereinafter referred to as a conventional combination machining tool) realized by simply combining a conventional valve guide mouth counterbore cutting tool 51 and a conventional valve seat press-fitting hole cutting tool 52 is provided. Suppose you use it. In this case, as shown in FIG. 6a, each of the four blades 51a to 51d of the conventional valve guide mouth counterbore cutting tool 51 has four blades 52a to 52d of the conventional valve seat press-fitting hole cutting tool 52. Are formed so as to be in phase with each other.
For this reason, if the conventional combination drilling tool is used to process the valve seat press-fitting hole, the valve guide opening counterbore, and the valve guide press-fitting hole in one step, the conventional valve seat press-fitting hole processing In contrast to the processing of the valve seat press-fitting hole by the blade 52, if there is a radial resistance applied during the processing of the valve guide mouth counterbore, there is an adverse effect that self-excited vibration occurs. Due to this adverse effect, the accuracy of the valve seat press-fitting hole, particularly the roundness, is deteriorated, so that the processing in one step becomes very difficult.
On the other hand, as shown in FIG. 6 b, each of the two blades 32 a and 32 b of the valve guide opening counterbore cutting tool 32 according to the embodiment of the present invention is a 4 of the valve seat press-fitting hole cutting tool 33. Each of the blades 33a to 33d is formed to have a different phase during rotation.
Therefore, when the valve seat press-fitting hole 11, the valve guide opening counterbore 12, and the valve guide press-fitting hole 13 are machined in one step with the drilling tool 21 according to one embodiment of the present invention, the valve seat press-fitting is performed. The degree of influence of the radial resistance applied when machining the valve guide mouth counterbore 12 to the machining of the valve seat press-fitting hole 11 by the hole machining tool 33, that is, the magnitude of the self-excited vibration is compared with the case of FIG. descend. Further, as described with reference to FIGS. 4 and 5, the radial resistance itself due to the valve guide opening counterbore cutting tool 32 is smaller than the conventional one, and therefore the degree of influence, that is, the magnitude of the self-excited vibration is further increased. Decrease further. Thereby, the accuracy of the valve seat press-fitting hole 11, particularly roundness can be ensured with high accuracy, and as a result, processing in one process can be easily realized.

  For the same purpose, as is apparent from FIG. 3, each of the blades 32a and 32b of the valve guide mouth counterbore cutting tool 32 according to one embodiment of the present invention includes four blades 31 for valve guide press-fitting hole processing. The blades are formed so as to have different phases. The phase relationship of the blades of the valve guide press-fitting hole cutting tool 31 and the valve seat press-fitting hole cutting tool 33 is not particularly limited, but is the same in this embodiment.

Next, the operation of the above drilling tool 21 will be described.
The base end portion 34 of the drilling tool 21 is attached to a spindle shaft (not shown) that is rotated by a predetermined machine tool (not shown). In this case, the axis of the drilling tool 21 (axis along line AA ′ in FIG. 3) coincides with the spindle axis.

  Thereafter, the drilling tool 21 is inserted into the cylinder head 1 from the tip of the drilling tool 21, that is, from the tip of the valve guide press-fitting drilling tool 31, while being rotated by the spindle shaft. To go. Here, it is assumed that the drilling tool 21 is inserted into the cylinder head 1 with its axis (A-A ′ line axis in FIG. 3) aligned with the X-X ′ line axis in FIG. 2. In this case, the valve seat press-fitting hole 11, the valve guide opening counterbore 12, and the valve guide press-fitting hole 13 are formed in the cylinder head 1 as shown in FIG. Formed.

According to this embodiment, there are the following effects.
(1) The valve guide mouth counterbore cutting tool 32 according to the present embodiment has the following first to third characteristics.
The first feature is that, as shown in FIG. 4, blades 32 a and 32 b that are in point contact with the workpiece 61 due to the cutting blade shape.
The second feature is that, as shown in FIG. 5, it has two blades 32a and 32b having a smaller number of blades than the conventional one.
The third feature is that, as shown in FIG. 6, the phase of each of the two blades 32a and 32b is the same as that of the rotation of each of the four blades 33a to 33d of the blade 33 for forming a valve seat press-fitting hole. This is different from the phase of.
According to the third feature, the degree of influence of the radial resistance applied when the valve guide opening counterbore 12 is processed on the processing of the valve seat press-fitting hole 11 by the valve seat press-fitting hole cutting tool 33, that is, the magnitude of self-excited vibration is the same phase. Compared with the case of. Further, since the radial resistance itself applied when machining the valve guide mouth counterbore 12 is smaller than that of the prior art from the first feature and the second feature, the degree of influence, that is, the magnitude of self-excited vibration is further reduced. To do. Thereby, the accuracy of the valve seat press-fitting hole 11, in particular, the roundness can be ensured with high accuracy. Therefore, the valve seat press-fitting hole 11, the valve guide opening base counterbore 12, and the valve guide press-fitting hole 13 are formed in one step. It can be easily realized by machining. As a result, it is possible to reduce the equipment investment cost and shorten the processing time as compared with the case where the conventional processing is performed in two steps.

It should be noted that the present invention is not limited to the present embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, the blade of the valve guide mouth counterbore cutting tool 32 has a bite blade shape in the present embodiment, but is not limited to this, as long as it has a shape that makes point contact with the workpiece. It can be of any shape.
For example, the number of blades of the counterbore blade 32 at the valve guide opening is set to 2 in the present embodiment. However, the number is not limited to the present embodiment. Can do.

DESCRIPTION OF SYMBOLS 11 Valve seat press-fitting hole 12 Valve guide opening counterbore 13 Valve guide press-fitting hole 21 Drilling tool 31 Valve guide press-fitting hole cutting tool 32 Valve guide opening counterbore cutting tool 32a Blade 32b Blade 33 Valve seat press-fitting hole cutting tool 34 Base edge

Claims (4)

A drilling tool for forming a hole into which a valve seat and a valve guide of an intake valve or an exhaust valve of an engine cylinder head are press-fitted in the cylinder head as a work,
A valve seat press-fitting hole forming tool for forming a valve seat press-fitting hole into which the valve seat is press-fitted, and
A valve guide press-fitting hole forming tool for forming a valve guide press-fitting hole into which the valve guide is press-fitted, and
A valve guide opening counterbore for forming the valve guide opening counterbore for guiding the valve guide to be press-fitted into the valve guide press-fitting hole;
With
The valve guide mouth counterbore cutting tool is:
A drilling tool comprising two blades that are arranged so as to be in a phase different from that of the blade of the valve seat press-fitting hole processing tool when rotating, and that make point contact with the workpiece. 2. The drilling tool according to claim 1, wherein the valve guide opening counterbore cutting tool has a bite blade shape and makes point contact with the workpiece. 3. The hole drilling according to claim 1, wherein the blade of the valve seat press-fitting hole processing blade and the valve guide press-fitting hole cutting blade are arranged so as to be in the same phase during rotation. Processing tool. A drilling tool for forming a hole into which a valve seat and a valve guide of an intake valve or an exhaust valve of an engine cylinder head are press-fitted in the cylinder head as a work,
A valve seat press-fitting hole forming tool for forming a valve seat press-fitting hole into which the valve seat is press-fitted, and
A valve guide press-fitting hole forming tool for forming a valve guide press-fitting hole into which the valve guide is press-fitted, and
In order to form a valve guide opening counterbore for guiding the valve guide to be press-fitted into the valve guide press-fitting hole in the workpiece, the phase of the blade of the valve seat press-fitting hole machining tool is different from that at the time of rotation. The valve guide mouth counterbore cutting tool having two blades arranged and point-contacted with the workpiece;
A drilling tool comprising
By performing one step of inserting while rotating with respect to the workpiece,
The valve seat press-fitting hole, the valve guide press-fitting hole, and the valve guide opening counterbore are formed in the workpiece.

Images