JP2002331447A - Seat part grinding method of fuel injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve machining accuracy of rough grinding and finish grinding of a seat part of a nozzle needle 3, and to integrate a rough grinding process and a finish grinding process into two processes from six processes by adopting an NC shift cylindrical grinding machine having a multistage grinding wheel 50. SOLUTION: A wheel spindle stock of the NC shift cylindrical grinding machine is advanced, and the rotating multistage grinding wheel 50 is cut in an outside surface of the seat part 12 to form first and second taper parts 35 and 36 having first and second taper angles 01 and 02 and a recess part 14 on the outside surface of the seat part 12 of the nozzle needle 3 in the same machine without attaching and detaching a workpiece (the rough grinding process). Thus, an attaching detaching frequency of the workpiece becomes only one time in the rough grinding process so that stable machining accuracy can be obtained, and since the rough grinding process can be integrated into one process from three processes, a manufacturing cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for grinding a seat portion of a fuel injection nozzle for spraying fuel into a combustion chamber of an internal combustion engine, and more particularly to a hole type fuel injection nozzle for spraying fuel into a combustion chamber of a diesel engine. The present invention relates to a sheet part grinding method.

[0002]

2. Description of the Related Art Conventionally, for example, in a grinding method of a seat portion of a nozzle needle of a hall type fuel injection nozzle for spraying fuel into a combustion chamber of a diesel engine,
A cam-type fixed-cut cylindrical grinder that processes only one direction (one surface) is used. And, as shown in FIG. 7, the seat portion 110 of the current nozzle needle is
1 has two levels of first and second sheet surfaces 111 and 112 on both sides thereof, and has two levels of second and third sheet surfaces 112 and 113 on both sides of the second ridge line 102; Face 112
Has a recess 114.

[0003]

However, in the current seat portion 110 of the nozzle needle, it is necessary to grind four surfaces including first to third seat surfaces 111 to 113 and a recess 114 as required specifications. In addition to the necessity of changing the grinding surface shape of the grinding wheel as a rotating tool for each surface, the shape of the nozzle needle sheet is very complicated, making it easy to process the nozzle needle seat. could not. As a result, high processing accuracy is required, and the production cost of the Hall-type fuel injection nozzle becomes extremely high.

[0004] Further, in the conventional grinding work of the sheet portion shape of the nozzle needle, a cam-type fixed-cut cylindrical grinding having a grinding wheel having a shape corresponding to the surface to be ground is performed in order to improve the processing accuracy after the outer surface is cut by a lathe. It is carried out using a board. First, the grindstone shaft of the grindstone head capable of reciprocating in the front-rear direction on the table of the cylindrical grinder, as shown in FIG.
As shown in (a), the seat portion 11 of the nozzle needle
A grinding wheel 121 having a grinding surface corresponding to the taper angle θ2 of the outer surface of 0 is mounted, the grinding wheel feed motor is operated to rotate the grinding wheel 121, and the nozzle needle is attached to the spindle of the headstock by an electromagnetic chuck or the like. And a headstock drive motor is operated to rotate a nozzle needle as a workpiece. Then, the grindstone base is advanced, and the rotating grinding grindstone 121 is cut into the outer surface of the sheet portion 110 by:
By making a cut at 0.01 to 0.02 mm, the outer surface of the seat portion 110 of the nozzle needle has a taper angle θ.
The sheet rough grinding for forming the second second tapered surface 132 is performed.

Next, as shown in FIG. 5 (b), a cylindrical grindstone 122 having a grindstone 122 having a grind surface corresponding to the taper angle θ1 of the outer surface of the sheet portion 110 of the nozzle needle is mounted on a grindstone shaft of a grindstone table. The nozzle needle is mounted on the spindle of the headstock of the panel using an electromagnetic chuck or the like. Then, the grindstone of the cylindrical grinder is advanced, and the rotating grindstone 122 is rotated.
Is cut into the outer surface of the sheet portion 110 of the rotating nozzle needle at a cutting amount: 0.01 to 0.02 mm, so that the outer surface of the sheet portion 110 of the nozzle needle is
The sheet relief rough grinding for forming the first tapered surface 131 having the taper angle θ1 is performed.

Next, as shown in FIG. 6A, a cylindrical grinding wheel 123 having a grinding surface 123 having a grinding surface corresponding to the taper angle θ1 of the outer surface of the sheet portion 110 of the nozzle needle is mounted on the grinding wheel shaft of the grinding wheel base. The nozzle needle is mounted on the spindle of the headstock of the panel using an electromagnetic chuck or the like. Then, the grinding wheel base of the cylindrical grinding machine is advanced, and the rotating grinding wheel 123 is rotated.
Is cut into the outer surface of the sheet portion 110 of the rotating nozzle needle at a cutting amount of 0.005 mm, thereby forming a first sheet surface 111 having a taper angle θ1 on the outer surface of the sheet portion 110 of the nozzle needle. Perform finish grinding.

Next, as shown in FIG. 6 (b), a cylindrical grinding wheel 124 having a grinding surface 124 having a grinding surface corresponding to the taper angle θ2 of the outer surface of the sheet portion 110 of the nozzle needle is mounted on the grinding wheel shaft of the grinding wheel base. The nozzle needle is mounted on the spindle of the headstock of the panel using an electromagnetic chuck or the like. Then, the grindstone 124 of this cylindrical grinder is advanced, and the rotating grindstone 124 is rotated.
Is cut into the outer surface of the sheet portion 110 of the rotating nozzle needle at a cutting amount of 0.005 mm, thereby forming a second sheet surface 112 having a taper angle θ2 on the outer surface of the sheet portion 110 of the nozzle needle. Perform grinding.

Next, as shown in FIG. 6 (c), a cylindrical grindstone 125 having a grindstone 125 having a grind surface corresponding to the taper angle θ3 of the outer surface of the sheet portion 110 of the nozzle needle is mounted on a grindstone shaft of a grindstone table. A nozzle needle is mounted on the spindle of the headstock of the panel using an electromagnetic chuck or the like. Then, the grindstone base of this cylindrical grinder is advanced, and the rotating grindstone 125 is rotated.
Is cut into the outer surface of the rotating nozzle needle sheet portion 110 at a cutting amount of 0.005 mm to form a third sheet surface 113 having a taper angle θ3 on the outer surface of the nozzle needle sheet portion 110. Perform grinding.

Finally, as shown in FIG. 7, a spindle of a cylindrical grinder in which a grinding wheel 126 having a grinding portion corresponding to the recess 114 on the outer surface of the sheet portion 110 of the nozzle needle is mounted on a grinding wheel shaft of a grinding wheel stand. The nozzle needle is mounted on the main spindle of the table using an electromagnetic chuck or the like. Then, the grinding wheel base of this cylindrical grinding machine is advanced, and the rotating grinding wheel 126 is rotated.
Recess grinding is performed to form a recess 114 in the second sheet surface 112 of the nozzle needle sheet portion 110 by cutting the outer surface of the rotating nozzle needle sheet portion 110, that is, the second sheet surface 112.

Therefore, the conventional grinding operation of the sheet portion of the nozzle needle includes a rough sheet grinding step, a rough sheet removing step, a sheet finishing finishing grinding step, a sheet finishing grinding step,
Six steps are required: a top finish grinding step and a recess grinding step. Then, each time each grinding step is performed, the other end of the nozzle needle is attached to the spindle of each headstock using an electromagnetic chuck or the like, or the other end of the nozzle needle is removed for the next grinding operation. However, since it is necessary to repeatedly perform the attachment and detachment work of the nozzle needle, the positioning accuracy of the axis of the nozzle needle varies, the processing accuracy of the nozzle needle sheet shape becomes poor, and the nozzle needle sheet shape becomes a desired shape. Could not be ground.

[0011]

SUMMARY OF THE INVENTION The present invention focuses on improving the positioning accuracy of a workpiece and simplifying a grinding operation. At least two or three or more grinding surfaces are used as rotary tools for grinding the outer surface of a workpiece. Provided is a method for grinding a sheet portion of a fuel injection nozzle, which can improve the processing accuracy of the shape of the sheet portion of the nozzle needle and reduce the manufacturing cost of the nozzle needle by employing a multi-stage grinding wheel having the same. With the goal.

[0012]

According to the first, eighth and ninth aspects of the present invention, there is provided a grinding machine using a multi-stage grinding wheel having at least two or more grinding surfaces as a rotary tool, Each grinding surface of the grindstone is cut into the outer surface of the sheet portion, and each sheet surface is ground to obtain the shape of the sheet portion in the same machine. As a result, the number of times of chucking of the workpiece, that is, the number of times of attachment / detachment of the nozzle needle can be reduced, so that the shape of the sheet portion of the nozzle needle can be processed with high precision.
In addition, the manufacturing cost of the nozzle needle can be reduced by integrating the processes from two processes to one process.

According to the second aspect of the present invention, the multi-stage grinding stone has a convex ground surface corresponding to the recess of the sheet portion. Then, each grinding surface of the multi-stage grindstone is cut into the outer surface of the sheet portion, and each sheet surface is ground, so that the shape of the sheet portion is obtained in the same machine. This makes it possible to reduce the manufacturing cost of the nozzle needle by integrating the three steps into one step.

According to the third aspect of the present invention, the grinding machine is provided with a multi-stage grinding wheel moving means for moving the multi-stage grinding wheel in a direction substantially orthogonal to the surface direction of the outer surface of the sheet portion. The grinding machine performs grinding of at least two or more stages of the sheet surface at one time, thereby reducing the manufacturing cost of the nozzle needle by integrating the processes from two or three processes to one process. it can.

According to the fourth aspect of the present invention, when the sheet surface angle on the side opposite to the injection hole from the annular ridge line is θ1 and the seat surface angle on the injection hole side from the ridge line is θ2, θ1
<Θ2 is satisfied. This makes it possible to easily grind the sheet portion of the nozzle needle into a desired shape (a substantially conical shape having at least two steps).

According to the fifth aspect of the present invention, there is provided a grinding machine using a multi-stage grinding wheel having at least three or more grinding surfaces as a rotary tool, and each grinding surface of the multi-stage grinding wheel is cut into the outer surface of the sheet portion. By grinding each sheet surface, the shape of the sheet portion is obtained in the same machine.
As a result, the number of times of chucking of the workpiece, that is, the number of times of attachment / detachment of the nozzle needle can be reduced, so that the shape of the sheet portion of the nozzle needle can be processed with high precision. In addition, the manufacturing cost of the nozzle needle can be reduced by integrating the processes from three processes to one process.

According to the invention described in claim 6, the grinding machine is provided with needle moving means for moving the nozzle needle in a direction parallel to the axial direction, and a multi-stage grindstone with respect to the surface direction of the outer surface of the sheet portion. A multi-stage grindstone moving means for moving in a direction substantially orthogonal to the wheel is provided. Then, the grinding machine performs at least three steps of grinding the sheet surface three times or more,
By integrating the steps from three steps to one step, the manufacturing cost of the nozzle needle can be reduced.

According to the seventh aspect of the present invention, the sheet surface angle on the opposite side of the injection hole from the first ridge line is set to θ1, and the sheet surface angle is closer to the injection hole than the first ridge line, and When the sheet surface angle on the opposite side of the injection hole from the second ridge line is θ2, and the sheet surface angle on the injection hole side of the second ridge line is θ3, θ1
<Θ2, θ2 <θ3. This makes it possible to easily grind the sheet portion of the nozzle needle into a desired shape (at least three or more steps of a substantially conical shape).

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Structure of Embodiment] An embodiment of the present invention will be described based on an embodiment with reference to the drawings. here,
FIG. 3 is a view showing a tip shape of a Hall-type fuel injection nozzle for a direct injection diesel engine.

In this embodiment, a direct fuel injection type diesel engine Hall-type fuel injection nozzle (hereinafter abbreviated as a Hall-type fuel injection nozzle) 1 includes a cylinder head (not shown) of a direct injection diesel engine (hereinafter referred to as an internal combustion engine). ) Is formed between a cylinder head and a piston (not shown) so that the fuel pressurized to a high pressure by a fuel injection pump (not shown) can be ignited and burned better. This is a fuel injection valve for an internal combustion engine that sprays into a combustion chamber (not shown).

The hole type fuel injection nozzle 1 is provided with a nozzle body 2 fastened and fixed to a distal end side of a nozzle holder (not shown) using a fastening member such as a retaining nut, and is reciprocally accommodated in the nozzle body 2.
It is composed of a nozzle needle 3 and the like that are closed by a spring load.

The nozzle body 2 is made of, for example, chromium molybdenum steel such as SCM415 or chromium such as SCR or carbon steel, and is formed in a circular tube shape. Inside the nozzle body 2, an inner hole 4 formed in the axial direction of the nozzle body 2, a valve seat portion 5 provided continuously to the tip of the inner hole 4 and forming a truncated cone-shaped hollow portion inside , And a suck hole 6 communicating with the valve seat 5. The inner hole 4, the valve seat 5, and the suck hole 6 are substantially coaxial.

A hemispherical circular top 7 in which a suck hole 6 is formed inside the nozzle body 2 has a plurality (in this example) so as to communicate between the suck hole 6 side and the combustion chamber side of the internal combustion engine. 2 to 8) injection holes (injection holes) 9 are formed on the same circumference. These injection holes 9 are provided in an injection passage (for example, having a hole diameter of φ
0.2 mm to 0.3 mm).

The nozzle needle 3 is, for example, an SCM415
It is made of chromium or carbon steel such as chromium molybdenum steel or SCR and is formed in a round bar shape. The nozzle needle 3 is constantly urged in a direction to close the plurality of injection holes 9 by a coil spring (not shown) as an urging means housed in the nozzle holder. This nozzle needle 3
An axial portion 11 having a cylindrical surface shape, and a substantially conical seat portion 12 provided on the distal end side with respect to the axial portion 11 are provided. The nozzle (reservoir) 13 is accommodated in a reciprocating manner while maintaining the clearance (nozzle chamber) 13.

Although not shown, the rear end of the nozzle needle 3 is slidably supported in the sliding portion of the nozzle body 2. Here, as is well known, the clearance 13 functions as a fuel passage through which high-pressure fuel supplied from the fuel injection pump passes through a fuel supply passage (not shown). Further, when the seat portion 12 is disengaged (lifted / lifted) from the valve seat portion 5 of the nozzle body 2, the nozzle needle 3 and the outer peripheral surface of the seat portion 12 (hereinafter referred to as a seat surface) are in contact with each other. A fuel passage (for example, a clearance of 0.25 to 0.30 mm) is formed between the fuel passage and the inner peripheral surface.

When the fuel injection into the combustion chamber of the internal combustion engine is completed, the seat portion 12 of the nozzle needle 3 is a substantially conical portion that seats (seats) on the valve seat portion 5 of the nozzle body 2. A stepped recess 14 is provided between the shaft 11 and the axial portion 11. This recess 14
Is an annular groove-shaped portion that is recessed from an imaginary line in the shape of a truncated cone that extends a second seat surface 22 (described later) of the seat portion 12. The inlet of the recess 14 is set to have a sufficiently large angle difference (for example, 45 °) or more with respect to the inclination angle (reverse taper angle) of the inner peripheral surface of the valve seat 5. Further, when the hole-type fuel injection nozzle 1 is closed, the distance between the recessed recess 14 and each injection hole 9 is determined by the seal length required for closing each injection hole 9 with the seat portion 12 of the nozzle needle 3. Is secured.

The seat portion 12 of the nozzle needle 3
From the tapered edge portion 15 on the axial direction portion 11 side to the pointed end portion 1
Up to 6, it has three levels of seat surfaces. That is, the sheet portion 12 includes a substantially frusto-conical first sheet surface (sheet relief portion) 21, an annular first ridgeline 31, an approximately frusto-conical second seat surface (sheet portion) 22, and an annular frustum. Second
A ridge line 32 and a substantially conical tip sheet relief portion 23 are provided. Then, the seat portion 12 of the nozzle needle 3
Is the angle of inclination (taper angle) of the first sheet surface 21 on the opposite side of each of the injection holes 9 from the first ridgeline 31, and is on the side of each of the injection holes 9 than the first ridgeline 31 and the second ridgeline. The inclination angle (taper angle) of the second sheet surface 22 on the opposite side of each of the injection holes 9 with respect to 32 is θ2, and the inclination angle (taper angle) of the leading sheet relief portion 23 with respect to the second ridgeline 32 is θ3. When θ1
<Θ2 and θ2 <θ3.

The tapered edge 33 at the upstream edge (the entrance of the recess 14) of the recess 14 provided on the second seat surface 22 makes line contact with the valve seat 5 of the nozzle body 2. Further, the recess portion 1 provided on the second seat surface 22 is provided.
The seat edge 34 at the downstream edge of the nozzle 4 (the outlet of the recess 14) is in line contact with the valve seat 5 of the nozzle body 2 to form a seat diameter. The first seat surface 21
Is smaller than the taper angle of the second seat surface 22, the first seat surface 21 does not sit on the valve seat portion 5 of the nozzle body 2 even when the valve is closed. Further, since the taper angle of the tip seat relief portion 23 is larger than the taper angle of the second seat surface 22, the tip seat relief portion 23 is seated (seat) on the valve seat portion 5 of the nozzle body 2 even when the valve is closed. There is no.

Next, a method of grinding the sheet portion of the nozzle needle 3 according to the present embodiment will be briefly described with reference to FIGS. Here, FIG.
FIG. 1B is a view showing a form grinding step of this embodiment, FIG. 1B is a view showing a rough grinding step of this embodiment, and FIG. 2 is a view showing a finish grinding step of this embodiment. .

Here, in the present embodiment, the nozzle needle 3
An NC shift cylindrical grinder is employed as a cylindrical grinder for performing rough grinding and finish grinding on the outer surface of the sheet portion 12 of FIG. The NC shift cylindrical grinder mounts a nozzle needle 3 which is a workpiece on the tip of a main shaft using an electromagnetic chuck or the like,
A headstock for rotating the workpiece, a first servomotor for rotating the spindle of the headstock, a table feed servomotor for reciprocating a table for fixing the headstock at an end in a thrust direction, a multi-stage grindstone 50 or a multi-stage A grindstone head having a grindstone 60 mounted on a grindstone shaft, a second servomotor for rotating the grindstone shaft of the grindstone head, and a grindstone head feed servo for cutting the grindstone head into the sheet portion 12 of the nozzle needle 3 at a predetermined angle. It is composed of a motor, a control panel for controlling each servomotor according to an input operation, and the like. Here, the spindle is rotatably supported by the headstock via a bearing.
Further, the grindstone shaft is rotatably supported by the grindstone base via a precision grindstone bearing (segment bearing).

The first servomotor is a needle driving means for rotating the nozzle needle 3 at a predetermined peripheral speed. Further, the second servo motor is a multi-stage grinding wheel driving unit that rotates the multi-stage grinding wheel 50 or the multi-stage grinding wheel 60 at a predetermined rotation speed. The table feed servomotor is a needle moving means for moving the nozzle needle 3 at a predetermined feed speed in a direction parallel to the axial direction. The servo motor for feeding the grinding wheel head is a multi-stage grinding wheel 50 or a multi-stage grinding wheel 6.
0 at a predetermined feed rate to the sheet portion 1 of the nozzle needle 3.
2 is a multi-stage grindstone moving means (grindstone head feed mechanism) for moving in a direction substantially orthogonal to the surface direction of the outer surface of No. In the rough grinding and finish grinding, a large amount of grinding fluid is applied to prevent clogging of the multi-stage grindstones 50 and 60 and cool the workpiece.

(A) Form grinding step The form grinding of the grinding surface of the multi-stage grinding wheel 50 is performed by the method shown in FIG.
(B) As shown in FIG.
This is performed using That is, the unevenness opposite to the shape to be machined is formed on the grinding surface of the grinding wheel to form the multi-stage grinding wheel 50. As shown in FIG. 1 (a), the first and second tapered portions 35 and 36 of the seat portion 12 of the nozzle needle 3 and the recessed portion 14 are opposite to each other on the formed ground surface of the formed rotary dresser 40. First and second tapered portions 4 having uneven shapes
1, 42 and a recess 43 are formed.

[0033] Such a general-purpose rotary dresser 40
As shown in FIG. 2, the first and second taper portions 35 and 36 of the sheet portion 12 of the nozzle needle 3 and the recess portion 1
First and second grinding surfaces 51 and 52 for rough grinding of the workpiece 4 and an anti-recess portion 53 are provided. Similarly, the first and second sheet surfaces 21 to 22 of the sheet portion 12 of the nozzle needle 3 are provided on the multi-stage grinding wheel 60 for finishing whose grinding surface is shaped by a general-purpose rotary dresser (not shown). ,
First to third for finish-grinding the leading sheet relief portion 23
Grinding surfaces 61 to 63 are provided. The dressing may use a diamond dresser in which a diamond of 1/4 to 2.0 carats of a single stone is attached to the tip of a rod, or a multi-stone dresser.

(B) Sheet rough grinding process After the outer surface is cut by a lathe, the grindstone shaft of a grindstone head capable of reciprocating in the front-rear direction on the table of the NC shift cylindrical grinder is shown in FIG. 1 (b). As shown, the first and second tapered portions 35 and 36 of the seat 12
First and second ground surfaces 51 and 52 corresponding to the taper angles θ1 and θ2 and the concave shape of the recess portion 14, and the anti-recess portion 5
The multi-stage grindstone 50 having the number 3 is mounted, and the multi-stage grindstone 50 is rotated by moving the grindstone feed servomotor. Further, the nozzle needle 3 is mounted on the spindle of the headstock using an electromagnetic chuck or the like, and the first servomotor is operated to rotate the nozzle needle 3.

Then, in the same machine of the NC shift cylindrical grinding machine, rough grinding is performed using a multi-stage grinding wheel 50. That is, the grindstone table is advanced to the outer surface side of the sheet portion 12, and the rotating multi-stage grindstone 50 is cut into the outer surface of the sheet portion 12 by:
The first and second taper portions 35 and 36 having the first and second taper angles θ1 and θ2 and the recess portion 14 are formed on the outer surface of the seat portion 12 of the nozzle needle 3 by making a cut at 0.01 to 0.02 mm. Perform rough grinding to form Therefore, in the rough grinding process of the present embodiment, the number of times of attachment / detachment (chucking) of the nozzle needle 3 as the workpiece is one, and therefore the first and second taper portions of the first and second taper portions 35 and 36 are provided. Stable machining accuracy can be obtained at the angles θ1 and θ2, the concave shape of the recessed portion 14 and the outer diameters of the tapered edge portion 33 and the sheet edge portion 34 which are the intersections, and compared with the conventional rough grinding method. , Three steps can be integrated into one step.

(C) Sheet Finish Grinding Step As shown in FIG. 2, the first and second sheet surfaces 21, 2 of the sheet portion 12 are attached to the grindstone shaft of the grindstone base of the NC shift cylindrical grinder.
2 and the first to third taper angles θ of the front sheet relief portion 23
A multi-stage grindstone 60 having first to third grinding surfaces 61 to 63 corresponding to 1 to θ3 is mounted, and the multi-stage grindstone 60 is rotated by moving a grindstone feed servomotor. Further, the nozzle needle 3 is mounted on the spindle of the headstock using an electromagnetic chuck or the like, and the first servomotor is operated to rotate the nozzle needle 3.

Then, the grindstone table is advanced to the outer surface side of the sheet portion 12, and the rotating multi-stage grindstone 60 is cut into the outer surface of the sheet portion 12 at a cutting amount of 0.005 mm, so that the sheet portion of the nozzle needle is formed. Finish grinding is performed on the outer surface to form the first sheet surface 21 having the first taper angle θ1. Subsequently, after the grindstone head is retracted to the side opposite to the outer surface side of the sheet portion 12, the table feed servomotor is moved to move the table on which the headstock is mounted in the thrust direction.

Then, the grindstone table is advanced to the outer surface side of the sheet portion 12, and the rotating multi-stage grindstone 60 is cut into the outer surface of the sheet portion 12 at a cutting amount of 0.005 mm. 12 on the outer surface
Finish grinding for forming the second sheet surface 22 having the taper angle θ2 is performed. Subsequently, after the grindstone head is retracted to the side opposite to the outer surface side of the sheet portion 12, the table feed servomotor is moved to further move the table on which the headstock is placed in the thrust direction.

Then, the grindstone table is advanced to the outer surface side of the sheet portion 12 and the rotating multi-stage grindstone 60 is cut into the outer surface of the sheet portion 12 at a cutting amount of 0.005 mm, so that the sheet portion of the nozzle needle is Finish grinding is performed on the outer surface to form the second sheet surface 22 having the second taper angle θ2. Therefore, the finish grinding process of the present embodiment is an NC shift grinding process in the same machine by the multi-stage grindstone 60, and the processing standard of the nozzle needle 3 as the workpiece is the same. , 22 and the tip sheet relief portion 23, the first to third taper angles θ1 to θ3, the outer diameters of the annular first and second ridgelines 31, 32 which are the respective intersections, and the tapered edge 33 which is the intersection. Further, the processing accuracy of the outer diameter of the sheet edge portion 34 can be improved. And, compared to the conventional finish grinding method, 3
The steps can be integrated into one step.

[Effects of the Embodiment] As described above, in the method of grinding the seat portion of the nozzle needle 3 of the fuel injection nozzle 1 of the present embodiment, the multi-stage grindstone is provided in the same machine from the conventional cam type fixed cut grinding method. NC with 50, 60
By performing an NC shift grinding process using a shift cylindrical grinder, the rough grinding process can be integrated from three processes to one process, and the finish grinding process can be integrated from three processes to two processes. That is, in the entire grinding process, the process integration from six processes to two processes can be achieved, and the manufacturing cost can be reduced.

Further, since the number of times of chucking of the nozzle needle 3 (processing reference) can be reduced, it is possible to realize highly accurate processing of the sheet shape of the nozzle needle 3. That is, it is possible to prevent a variation in the positioning accuracy of the axis of the nozzle needle 3.
The processing accuracy of the sheet portion shape can be improved, and the sheet portion shape of the nozzle needle 3 can be roughly ground and finish ground to a desired shape.

[Modification] In this embodiment, an NC (numerical control) in which multi-stage grinding wheels 50 and 60 are provided in the same machine as a grinding machine.
Although the shift cylindrical grinder is used, a CNC shift cylindrical grinder provided with multi-stage grinding wheels 50 and 60 in the same machine may be used as the grinding machine. Further, a centerless grinding machine provided with the multi-stage grinding wheels 50 and 60 in the same machine may be used.

In this embodiment, the nozzle needle 3 as a workpiece is attached to the spindle of the headstock using an electromagnetic chuck or the like, but the nozzle needle 13 as a workpiece is attached to the spindle of the headstock with a hydraulic chuck or the like. You may make it attach using. Further, the axial portion (shaft portion) 11 of the nozzle needle 13 may be rotatably supported by a guide roller or a bearing. Alternatively, the multi-stage grindstone may be attached at an angle to the outer surface of the work (workpiece) to perform angular slide grinding.

In the present embodiment, the table on which the headstock holding the workpiece is placed is stopped, and plunge cut grinding (not shown) in which the multi-stage grindstones 50 and 60 are cut into the outer surface of the sheet portion 12 of the nozzle needle 3 of the workpiece. 0.0 per work rotation
02 to 0.003 mm), the table on which the headstock holding the workpiece is placed is reciprocated, and the multi-stage grindstones 50 and 60 are moved at each turn or each reciprocation to the nozzle needle 3 of the workpiece. Plunge cut grinding (cutting amount: rough grinding 0.01 to
(0.02 mm, finish grinding 0.005 mm).

In this embodiment, the present invention is applied to a sheet part grinding method or a sheet part grinding apparatus (NC shift) for rough- and finish-grinding the tip of the sheet part 12 of the nozzle needle 3 as shown in FIG. Although an example of a cylindrical grinder has been described, the present invention is applied to a sheet part grinding method or a sheet part grinding apparatus for rough- and finish-grinding the tip shape of the sheet part 12 of the nozzle needle 3 as shown in FIG. (NC shift cylindrical grinder). In this case, the recess 14 is provided on the upstream side of the first seat surface 21 of the seat 12 of the nozzle needle 3. 3 and 4
The recessed portion 14 may not be provided on the outer surface of the sheet portion 12.

[Brief description of the drawings]

FIG. 1A is an explanatory view showing a form grinding step of the present embodiment, and FIG. 1B is an explanatory view showing a rough grinding step of the present embodiment.

FIG. 2 is an explanatory view showing a finish grinding step of the present embodiment.

FIG. 3 is a cross-sectional view showing a tip shape of a hall-type fuel injection nozzle for a direct injection diesel engine (Example).

FIG. 4 is a cross-sectional view illustrating a tip shape of a direct injection type diesel engine Hall-type fuel injection nozzle (modification).

FIGS. 5A and 5B are explanatory views showing a conventional rough grinding process.

FIGS. 6A to 6C are explanatory views showing a conventional finish grinding step.

FIG. 7 is an explanatory view showing a recess grinding step (prior art).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hall-type fuel injection nozzle 2 Nozzle body 3 Nozzle needle 5 Valve seat part 6 Suck hole 9 Injection hole 12 Seat part 14 Recess part 16 Pointed end 21 First seat surface (Sheet relief part) 22 Second seat surface (Seat part) 23 Front sheet relief portion 31 First ridgeline 32 Second ridgeline 33 Tapered edge portion 34 Seat edge portion 41 First tapered portion 42 Second tapered portion 50 Multi-stage grinding stone 51 First grinding surface 52 Second grinding surface 60 Multi-stage grinding stone 61 First grinding surface 62 Second ground surface 63 Third ground surface

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3C043 AA01 AA11 AA13 AA14 CC03 3C049 AA03 AA11 CA02 CB03 3G066 AA07 AB02 AD12 BA51 BA55 BA61 CC14 CC26 CD14 CD30

Claims (9)

[Claims] 1. A nozzle body having a valve seat portion forming a substantially conical hollow portion therein, and a substantially conical seat portion accommodated in the nozzle body so as to be reciprocally movable and seated on the valve seat portion. And a nozzle needle having a seat portion having at least two or more stages of seat surfaces, wherein the multi-stage grinding wheel having at least two or more stages of grinding surface is rotated by a rotary tool. The grinding machine has a grinding machine, and the grinding machine cuts each grinding surface of the multi-stage grindstone into an outer surface of the sheet portion, and grinds each sheet surface, thereby forming the sheet portion shape in the same machine. A method of grinding a sheet portion of a fuel injection nozzle, characterized by obtaining. 2. The method according to claim 1, wherein the sheet portion has a concave recess in the nozzle needle for separating a flow of fuel, and the multi-stage grinding wheel. Has a convex ground surface corresponding to the recessed portion, and cuts each ground surface of the multi-stage grindstone into an outer surface of the sheet portion, and grinds each of the sheet surfaces. A method for grinding a seat portion of a fuel injection nozzle, wherein the shape is obtained in the same machine. 3. The method for grinding a sheet portion of a fuel injection nozzle according to claim 1 or 2, wherein the grinding machine makes the multi-stage grinding wheel substantially perpendicular to a surface direction of an outer surface of the sheet portion. A multi-stage grindstone moving means for moving in a direction, wherein the grinding of the sheet surface of at least two or more stages is performed in a single operation. 4. A fuel injection nozzle manufactured by using the method for grinding a seat portion of a fuel injection nozzle according to claim 1, wherein the nozzle body is located downstream of the valve seat. The nozzle portion has an annular ridgeline between two adjacent seat surfaces, and a seat surface angle on the opposite side of the nozzle hole from the ridgeline is θ1.
And the sheet surface angle on the injection hole side of the ridge line is θ2
The fuel injection nozzle satisfies the relationship of θ1 <θ2. 5. A nozzle body having a valve seat portion forming a substantially conical hollow portion therein, and a substantially conical seat portion accommodated in the nozzle body so as to be reciprocally movable and seated on the valve seat portion. And a nozzle needle having a nozzle portion having at least three stages of seat surfaces in the seat portion, comprising: a multi-stage grinding wheel having at least three stages of grinding surfaces; The grinding machine has a grinding machine, and the grinding machine cuts each grinding surface of the multi-stage grindstone into an outer surface of the sheet portion, and grinds each sheet surface, thereby forming the sheet portion shape in the same machine. A method of grinding a sheet portion of a fuel injection nozzle, characterized by obtaining. 6. The method according to claim 5, wherein the grinding machine comprises a needle moving means for moving the nozzle needle in a direction parallel to an axial direction, and the multi-stage grinding wheel. A multi-stage grindstone moving means for moving in a direction substantially orthogonal to a surface direction of an outer surface of the sheet portion, wherein the at least three or more stages of the sheet surface are ground three times. Sheet part grinding method. 7. A fuel injection nozzle manufactured by using the method of grinding a seat portion of a fuel injection nozzle according to claim 5 or 6, wherein the nozzle body has an injection hole located downstream of the valve seat. The seat portion of the nozzle needle has an annular ridge line between two adjacent seat surfaces, and the seat surface angle on the opposite side of the injection hole from the first ridge line is θ1. And on the injection hole side than the first ridge line,
And when the sheet surface angle on the side opposite to the injection hole with respect to the second ridge line is θ2 and the sheet surface angle on the injection hole side with respect to the second ridge line is θ3, θ1 <θ2; And a relationship of θ2 <θ3 is satisfied. 8. A method of grinding a tapered portion of a workpiece having a substantially conical tapered portion and having at least two or more steps of tapered surface in the tapered portion, wherein the method has at least two or more steps of ground surface. A grinding machine using a multi-stage grinding wheel as a rotary tool, the grinding machine cuts each grinding surface of the multi-stage grinding wheel into an outer surface of the tapered portion, and grinds each of the tapered surfaces, thereby forming the tapered portion. A method for grinding a tapered portion of a workpiece, wherein the shape is obtained in the same machine. 9. The method for grinding a tapered portion of a workpiece according to claim 8, wherein the tapered portion of the workpiece is a substantially conical seat portion of a nozzle needle of a fuel injection nozzle. A method for grinding a tapered portion of a workpiece, comprising at least two or more stages of seat surfaces between a tapered edge portion and a pointed portion on the axial direction side.