JP6287881B2 - Valve seat processing method - Google Patents

Description

  The present invention relates to a method for processing a valve seat portion.

  The cylinder head of the engine is provided with a combustion chamber and an intake / exhaust port leading to the combustion chamber. A valve seat with which the back surface of the valve abuts is provided at the periphery of the opening end of the intake / exhaust port on the combustion chamber side. When the valve seat and the valve come into contact with each other, the airtightness of the combustion chamber is maintained.

  Heat resistance and wear resistance are required for a valve seat with which the valve repeatedly contacts in a high temperature environment. Therefore, in the valve seat, an annular counterbore groove is formed by machining at the opening edge periphery of the intake / exhaust port of the cylinder head rough shape member, and a dissimilar metal layer made of a copper alloy or the like is formed in the counterbore groove. Is obtained. As a method for forming such a dissimilar metal layer, a laser cladding method is known in which a clad layer (dissimilar metal layer) is formed by irradiating a laser beam while supplying metal powder to a counterbored groove.

  The clad layer formed by the laser clad method is cut into a predetermined shape. Here, a boundary layer made of a high hardness intermetallic compound is formed at the boundary between the cladding layer and the cylinder head rough profile. Therefore, when the same position of the cutting tool comes into contact with the boundary layer at the time of cutting, there is a problem that the position of the cutting tool is locally damaged and the life of the cutting tool is remarkably shortened.

  In Patent Document 1 (see, for example, FIGS. 2 and 3, etc.), by providing a guide surface 15 on the port opening end side of a concave groove (counterbored groove) 14, the life of the blade is extended. Further, chamfered corner portions 18 and 19 are provided on the corner edge portion 16 on the back side of the port and the corner edge portion 17 on the port opening end side, respectively.

JP 2000-326145 A

The inventor has found the following problems regarding the method of processing the valve seat portion.
In Patent Literature 1, since the dissimilar metal layer (cladding layer) 20 is cut by plunge processing, cutting is performed while feeding the cutting tools (cutting tools) 7 and 9 in the axial direction of the groove 14. Therefore, damage to the cutting tool 9 due to the boundary layer 21 formed on the side wall of the concave groove 14 becomes a problem (see, for example, FIG. 5 of Patent Document 1). Therefore, the guide surface 15 and the chamfered corner portion 19 are provided on the port opening end side to suppress damage to the cutting tool 9. Since the contact point between the boundary layer 21 formed on the bottom surface of the concave groove 14 and the cutting tool 7 changes with the progress of cutting, that is, the cutting tool 7 is fed, the above-described problem does not occur in the cutting tool 7.

By the way, with respect to the plunge process in which the cutting tool is always in contact with the workpiece, a contouring process in which the cutting tool is in intermittent contact with the workpiece is known. In the contouring process, the cutting load is reduced compared to the plunge process, and the consumption of the cutting tool is suppressed.
In the case of the contouring process, the clad layer (dissimilar metal layer 20 of Patent Document 1) is moved while moving the cutting tool in a direction perpendicular to the axis of the counterbored groove instead of the axial direction of the counterbored groove (the recessed groove 14 of Patent Document 1) To cut. Therefore, if it is patent document 1, the damage of the blade tool by the boundary layer 21 formed in the bottom face instead of the side wall of the ditch | groove 14 will be a problem.
Here, in patent document 1, since the chamfered corner part 18 is provided in the bottom face of the ditch | groove 14, the contact point of a cutting tool and the boundary layer 21 changes with progress of cutting, and the damage of a cutting tool is suppressed. it is conceivable that.

However, in Patent Document 1, when the dissimilar metal layer 20 is formed in a state in which the axial direction of the concave groove 14 is along the vertical direction, there is a problem that the molten metal tends to sag from the chamfered corner portion 18 to the back side of the port. .
In addition, when forming the dissimilar metal layer 20 while tilting the axis of the groove 14 so that the molten metal does not drip, it is necessary to rotate the entire cylinder head rough shape member, and the apparatus becomes large.

  This invention is made | formed in view of the above, Comprising: While suppressing dripping of the molten metal at the time of forming a clad layer, it suppresses damage to the blade tool at the time of contouring a clad layer.

A method for processing a valve seat portion according to an aspect of the present invention includes:
When forming an annular counterbore groove at the opening end of the port on the combustion chamber side in the cylinder head rough profile, an inclined portion inclined toward the combustion chamber side from the outside to the inside is formed on the bottom surface of the counterbore groove. Step to put
Irradiating the metal powder supplied to the counterbored grooves with a laser beam in a state where the axial direction of the counterbored grooves is along the vertical direction, and forming a cladding layer for a valve seat;
Cutting the clad layer together with the cylinder head rough shape material by a contouring process.

  In the valve seat portion processing method according to one aspect of the present invention, an inclined portion that is inclined toward the combustion chamber side from the outside to the inside of the counterbored groove is formed on the bottom surface of the counterbored groove. Therefore, dripping of the molten metal when forming the cladding layer can be suppressed. Further, when the contouring process is performed, the contact point between the cutting tool and the boundary layer changes with the progress of cutting, and damage to the cutting tool can be suppressed. That is, it is possible to suppress dripping of the molten metal when forming the cladding layer, and it is possible to suppress damage to the blade tool when contouring the cladding layer.

  In the valve seat portion processing method according to another aspect of the present invention, a convex portion protruding toward the combustion chamber is formed on the bottom surface of the counterbored groove, and a portion of the convex portion is inclined. The part can also be configured. Also in this embodiment, dripping of the molten metal when forming the cladding layer can be particularly effectively suppressed.

  In the valve seat portion processing method according to yet another aspect of the present invention, a notch groove is formed in the bottom surface of the counterbore groove, and a part of the notch groove constitutes the inclined portion. It can also be done. Even in this aspect, damage to the blade when the clad layer is contoured can be particularly effectively suppressed.

  According to the present invention, it is possible to suppress dripping of the molten metal when forming the cladding layer, and it is possible to suppress damage to the cutting tool when contouring the cladding layer.

It is a perspective view which shows typically the outline | summary of the clad layer formation in the processing method of the valve seat part which concerns on 1st Embodiment. It is sectional drawing of the laser processing head which concerns on 1st Embodiment. It is sectional drawing which shows the detail of the processing method of the valve seat part which concerns on 1st Embodiment. It is sectional drawing which shows the detail of the processing method of the valve seat part which concerns on 1st Embodiment. It is sectional drawing which shows the detail of the processing method of the valve seat part which concerns on 1st Embodiment. It is sectional drawing which shows the detail of the processing method of the valve seat part which concerns on 2nd Embodiment. It is sectional drawing which shows the detail of the processing method of the valve seat part which concerns on the modification of 2nd Embodiment.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

(First embodiment)
First, with reference to FIGS. 1-5, the processing method of the valve seat part which concerns on 1st Embodiment is demonstrated. FIG. 1 is a perspective view schematically showing an outline of clad layer formation in the valve seat portion processing method according to the first embodiment. FIG. 2 is a cross-sectional view of the laser processing head according to the first embodiment. 3-5 is sectional drawing which shows the detail of the processing method of the valve seat part which concerns on 1st Embodiment.

  With reference to FIG. 1, the outline | summary of the clad layer formation in the processing method of the valve seat part which concerns on 1st Embodiment is demonstrated. First, the configuration of the cylinder head rough profile 10 will be described. The cylinder head rough shape member 10 is a casting made of, for example, cast iron or aluminum alloy. As shown in FIG. 1, the cylinder head rough profile 10 includes a plurality of combustion chambers 13. Each combustion chamber 13 includes an intake port 11 and an exhaust port 12. Then, in each of the intake port 11 and the exhaust port 12, a counterbored groove 14 for forming a cladding layer is formed by machining on the periphery of the opening end on the combustion chamber 13 side.

  The rough cylinder head member 10 shown in FIG. 1 is for a four-cylinder 16 valve, and includes two intake ports 11 and two exhaust ports 12 in each of four combustion chambers 13. As a matter of course, the number of the combustion chambers 13, the intake ports 11 and the exhaust ports 12 is not limited to the example of FIG.

  As shown in FIG. 1, a clad layer is formed by irradiating a laser beam (optical axis A2) while supplying metal powder from the laser processing head 40 to the counterbored grooves 14. The laser processing head 40 makes one rotation around the central axis A1 of the annular counterbored groove 14, whereby a clad layer can be formed on the entire periphery of the counterbored groove 14. The central axis A <b> 1 is an axis that passes through the center of the counterbored groove 14 and is perpendicular to the bottom surface of the counterbored groove 14. In each of the intake port 11 and the exhaust port 12, the clad layer is formed after adjusting the posture of the cylinder head rough shape member 10 with the central axis A1 of the counterbored groove 14 along the vertical direction.

  Note that the state in which the central axis A1 of the counterbored groove 14 is along the vertical direction does not necessarily need to be a state in which the direction of the central axis A1 is exactly matched with the vertical direction. When forming the cladding layer, if the molten metal does not sag, the cylinder head rough profile 10 may be installed with the central axis A1 of the counterbored groove 14 slightly inclined from the vertical direction.

  Next, the configuration of the laser processing head 40 will be described with reference to FIG. The laser processing head 40 includes an inner nozzle 41, an outer nozzle 42, and a raw material supply pipe 43. That is, the laser processing head 40 has a coaxial double tube structure composed of an inner nozzle 41 and an outer nozzle 42 both having the optical axis A2 of the laser beam 30 as a central axis.

  Specifically, the laser beam 30 is emitted from the inner nozzle 41. Further, an inert gas and metal powder supplied via the raw material supply pipe 43 are discharged from between the inner nozzle 41 and the outer nozzle 42. That is, the discharge axis of the metal powder and the inert gas is coaxial with the optical axis A2 of the laser beam 30. Examples of the inert gas include argon gas and nitrogen gas.

  Thus, the laser processing apparatus can be made compact by integrating the irradiation of the laser beam and the supply of the metal powder and the inert gas. In FIG. 1, the raw material supply pipe 43 is omitted.

  Next, with reference to FIGS. 3-5, the detail of the processing method of the valve seat part which concerns on 1st Embodiment is demonstrated. Since the processing method of the valve seat portion is the same on the intake port 11 side and the exhaust port 12 side, the intake port 11 side will be described.

  First, as shown in FIG. 3, an annular counterbore groove 14 is formed by machining on the periphery of the opening end of the intake port 11 of the cylinder head rough shape member 10 on the combustion chamber 13 side. The counterbored groove 14 includes a bottom surface 14a, a slope 14b, and a side wall 14c.

  Here, in the valve seat portion processing method according to the first embodiment, a convex portion 15 protruding toward the combustion chamber is formed on the bottom surface 14 a of the counterbored groove 14. That is, an inclined portion 15 a is formed on the bottom surface 14 a of the counterbored groove 14 so as to incline toward the combustion chamber from the outside to the inside of the counterbored groove 14.

  Next, as shown in FIG. 4, a laser beam (optical axis A <b> 2) is irradiated while supplying metal powder from the laser processing head 40 to the counterbored grooves 14. As a result, the metal powder is melted and solidified inside the counterbore groove 14 to form the cladding layer 20 for the valve seat. Here, since the laser processing head 40 makes one rotation around the central axis A <b> 1 of the annular counterbored groove 14, the cladding layer 20 can be formed on the entire periphery of the counterbored groove 14.

  Defects are likely to occur in the cladding layer 20 at the corners of the counterbored grooves 14. However, the slope 14b provided between the bottom surface 14a and the side wall 14c suppresses defects in the cladding layer 20 at the corners of the counterbored groove 14.

  Furthermore, as described above, the bottom surface 14a of the counterbored groove 14 is formed with an inclined portion 15a that inclines toward the combustion chamber from the outside to the inside of the counterbored groove 14. Therefore, dripping of the molten metal when forming the cladding layer 20 can be suppressed.

  Here, the inclination angle θ2 of the inclined portion 15a with respect to the bottom surface 14a of the counterbored groove 14 is preferably 10 ° or more. If it is less than 10 °, dripping of the molten metal cannot be sufficiently suppressed. On the other hand, the inclination angle θ2 of the inclined portion 15a is preferably smaller than the inclination angle θ1 of the optical axis A2 of the laser beam 30 with respect to the bottom surface 14a of the counterbored groove 14. Thereby, interference with the laser beam 30 and the convex part 15 can be prevented. The inclination angle θ1 of the optical axis A2 of the laser beam 30 is about 45 °.

  Next, as shown in FIG. 5, the clad layer 20 is cut together with the cylinder head rough shape member 10 by contouring. The cutting tool 50 for contouring includes a support portion 51 and cutting tools 52 a and 52 b fixed to the support portion 51. The cutting tools 52a and 52b are, for example, cemented carbide tips.

  The cutting tool 50 moves from the inside to the outside of the counterbored groove 14 while rotating at high speed about the rotation axis A3. Thereby, the clad layer 20 and the cylinder head rough profile 10 are cut to the cutting shape indicated by the two-dot chain line. Specifically, the combustion chamber side guide surface 22a is formed by the blade 52a. The port back side guide surface 22b is formed by the cutting tool 52b. The valve seat surface 23 is finally formed by further cutting the cladding layer 20.

  Here, as shown in FIG. 5, a boundary layer 21 made of a high-hardness intermetallic compound is formed at the boundary between the cladding layer 20 and the cylinder head rough profile 10. Therefore, when the same position of the cutting tools 52a and 52b comes into contact with the boundary layer 21 during cutting, the positions of the cutting tools 52a and 52b are locally damaged, and the life of the cutting tools 52a and 52b is remarkably shortened.

  As shown in FIG. 5, in the contouring process, the clad layer 20 is cut while moving the cutting tools 52a and 52b in a direction perpendicular to the central axis A1 of the counterbored groove 14. Therefore, damage to the blade 52b due to the boundary layer 21 formed on the bottom surface 14a of the counterbore groove 14 becomes a problem. The contact point between the boundary layer 21 formed on the side wall 14c of the counterbore groove 14 and the cutting tool 52a changes with the progress of cutting, so that the above-described problem does not occur in the cutting tool 52a.

  Here, the bottom surface 14a of the counterbored groove 14 according to the first embodiment is formed with an inclined portion 15a that is inclined toward the combustion chamber from the outside of the counterbored groove 14 toward the inside. Therefore, when the cladding layer 20 is contoured, the contact point between the cutting tool 52b and the boundary layer 21 changes with the progress of cutting, and damage to the cutting tool 52b can be suppressed. In FIG. 5, the contact range with the boundary layer 21 in the blade 52b was typically shown.

  As described above, in the processing method for the valve seat portion according to the first embodiment, the inclined portion 15a is formed on the bottom surface 14a of the counterbored groove 14 so as to incline toward the combustion chamber from the outside to the inside of the counterbored groove 14. ing. Therefore, dripping of the molten metal when forming the cladding layer 20 can be suppressed. Further, when the clad layer 20 is contoured, the contact point between the blade 52b and the boundary layer 21 changes with the progress of cutting, and damage to the blade 52b can be suppressed.

  That is, the inclined portion 15a formed on the bottom surface 14a of the counterbored groove 14 suppresses dripping of the molten metal when forming the cladding layer 20, and suppresses damage to the blade 52b when contouring the cladding layer 20. can do.

(Second Embodiment)
Next, with reference to FIG. 6, the processing method of the valve seat part which concerns on 2nd Embodiment is demonstrated. FIG. 6 is a cross-sectional view showing details of the method for processing the valve seat portion according to the second embodiment. FIG. 6 according to the second embodiment corresponds to FIG. 5 according to the first embodiment.

  In the first embodiment, the bottom surface 14a of the counterbored groove 14 is formed with a convex portion 15 projecting toward the combustion chamber on the bottom surface 14a. A part of the convex portion 15 constitutes an inclined portion 15 a that is inclined toward the combustion chamber side from the outside to the inside of the counterbored groove 14 on the bottom surface 14 a of the counterbored groove 14.

  On the other hand, in the second embodiment, a notch groove 16 having a triangular cross section is formed on the bottom surface 14a of the counterbored groove 14. The cutout groove 16 is annular as in the counterbore groove 14 in plan view. The slope on the inner side of the notch groove 16 constitutes an inclined portion 16a that slopes toward the combustion chamber from the outside to the inside of the counterbored groove 14 on the bottom surface 14a of the counterbored groove 14.

  Also in the valve seat processing method according to the second embodiment, the bottom surface 14a of the counterbored groove 14 is formed with an inclined portion 16a that inclines toward the combustion chamber from the outside of the counterbored groove 14 toward the inside. Therefore, dripping of the molten metal when forming the cladding layer 20 can be suppressed. Further, when the clad layer 20 is contoured, the contact point between the blade 52b and the boundary layer 21 changes with the progress of cutting, and damage to the blade 52b can be suppressed.

  In other words, the inclined portion 16a formed on the bottom surface 14a of the counterbored groove 14 suppresses dripping of the molten metal when forming the cladding layer 20, and also prevents damage to the blade 52b when contouring the cladding layer 20. can do.

  Furthermore, in the second embodiment, since there is no interference with the laser beam 30 in the first place, the inclination angle θ2 of the inclined portion 16a can be made larger than that in the first embodiment. Therefore, the contact range with the boundary layer 21 in the blade 52b can be expanded, and damage to the blade 52b can be more effectively suppressed.

(Modification of the second embodiment)
Next, with reference to FIG. 7, the processing method of the valve seat part which concerns on the modification of 2nd Embodiment is demonstrated. FIG. 7 is a cross-sectional view showing details of a method for processing a valve seat portion according to a modification of the second embodiment. FIG. 7 according to the modification of the second embodiment corresponds to FIG. 6 according to the second embodiment.
As shown in FIG. 7, the cross-sectional shape of the notch groove 16 is not limited to a triangular shape, and may be a substantially semicircular shape. Also in the modified example of the second embodiment, the same effect as that of the second embodiment can be obtained.

Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.
For example, metal powder that is a raw material of the clad layer 20 may be supplied to the counterbore groove 14 using a nozzle different from the laser processing head 40. Further, it is not necessary for the inert gas to be discharged from the same laser processing head.

DESCRIPTION OF SYMBOLS 10 Cylinder head rough shape material 11 Intake port 12 Exhaust port 13 Combustion chamber 14 Counterbored groove 14a Bottom surface 14b Inclined surface 14c Side wall 15 Convex part 15a Inclined part 16 Notch part 16a Inclined part 20 Clad layer 21 Boundary layer 22a Combustion chamber side guide surface 22b Port Back side guide surface 30 Laser beam 40 Laser processing head 41 Inner nozzle 42 Outer nozzle 43 Raw material supply pipe 50 Cutting tool 51 Support portions 52a, 52b Cutting tool

Claims (1)

When forming an annular counterbore groove at the opening end of the port on the combustion chamber side in the cylinder head rough profile, an inclined portion inclined toward the combustion chamber side from the outside to the inside is formed on the bottom surface of the counterbore groove. Step to put
Irradiating the metal powder supplied to the counterbored grooves with a laser beam in a state where the axial direction of the counterbored grooves is along the vertical direction, and forming a cladding layer for a valve seat;
Cutting the cladding layer together with the cylinder head rough shape material by contouring , and
A notch groove is formed on the bottom surface of the counterbore groove,
A part of the notch groove constitutes the inclined portion,
Processing method of valve seat part.

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