JP2002307239A - Electrochemical machining device and electrochemical machining method for common rail - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical machining method and an electrochemical machining device for a common rail that can easily, uniformly and simultaneously round internal wall angular parts formed at connection parts between a plurality of distribution passages and an accumulator. SOLUTION: Since an electrolyte flows out to the distribution passages 21 due to almost uniform pressure in an electrode pipe 50, the outflow quantity to each distribution passage of a plurality of distribution passages 21 becomes almost equal. The electrolyte forms the flow that collides with the end face of a flange part 36 to flow radially outward, and the flow that flows in the circumferential direction. With the radially outward flow and the circumferential flow, the flow of the electrolyte becomes almost equal in the whole periphery of a doughnut-shaped remainder space of U-shaped cross section formed around the flange part 36. The electrolytic current comes around the internal wall angular parts 22 of the common rail 20 along the flow of the electrolyte, so that it removes the surface layers of the internal wall angular parts 22 and rounds the internal wall angular parts 22 almost uniformly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic processing method and an electrolytic processing apparatus for a common rail, and more particularly to an electrolytic processing method and an electrolytic processing apparatus for rounding an inner wall corner formed at a connection portion between a pressure accumulation chamber and a distribution passage of a common rail.

[0002]

2. Description of the Related Art Conventionally, a common rail for storing fuel supplied to an injector at a high pressure has been known. As shown in FIG. 2, a pressure accumulation chamber 23 of a common rail and a distribution passage 21 for supplying fuel from the pressure accumulation chamber 23 to the plurality of injectors 10.
Is formed at the corner 22 of the inner wall of the common rail. Since high-pressure fuel is stored in the pressure accumulating chamber 23, it is desirable to round the inner wall corner 22 so that stress received from the fuel does not concentrate on the inner wall corner 22 in order to improve pressure resistance.

As a process for rounding a corner formed on the inner wall of a pipe, electrolytic processing, polishing using free abrasive grains, and the like are known. The corners formed at a plurality of places on the inner wall of the pipe and separated from each other can be rounded at a time, the processing speed is relatively fast,
Considering that the running cost is small, electrolytic machining is the best method for rounding the corner 22 of the inner wall of the common rail.

The following two methods can be considered as a method of rounding the corner 22 of the inner wall of the common rail by electrolytic processing.
These methods are generally used for deburring and the like. The first method is to use the inner wall surface 2 forming the accumulator chamber 23.
4, a tube or rod-shaped electrode facing the plurality of corners 22 is inserted into the accumulator 23 at a predetermined interval, and the inner wall surface 24 is inserted.
This is a method in which an electrolytic solution is caused to flow between the electrode and the electrode, and the surface layer of the corner portion 22 is removed by the flow of the electrolytic solution flowing from the pressure accumulation chamber 23 to the distribution passage 21. The second method is a method in which a rod-shaped electrode is inserted into each of the distribution passages 21 and the electrolytic solution flows from the accumulator 23 to the distribution passage 21.

[0005]

However, according to the first method, the amount of removal of the corners 22 at the upstream and downstream sides of the flow of the electrolyte between the inner wall surface 24 of the accumulator chamber 23 and the electrode is reduced. There is a problem of non-uniformity. On the other hand, according to the second method, since the electrodes are inserted into the respective distribution passages 21, there is no problem that the removal amount of the corners 22 becomes uneven. However, it is necessary to insert an electrode into each of the distribution passages 21, and since the inner diameter of the distribution passage 21 has been reduced in recent years, there is a problem that the working process becomes complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a common rail electrolytic processing method and an electrolytic processing apparatus for easily and uniformly rounding an inner wall corner formed at a connection portion between a plurality of distribution passages and a pressure accumulation chamber at a time. .

[0007]

According to a method of electrolytic machining a common rail according to claim 1, a cylinder having a plurality of openings communicating with the distribution passage and having an inner diameter larger than the inner diameter of the distribution passage and abutting against the inner wall of the accumulator chamber. The part to be subjected to electrolytic processing by inserting an insulating member in the form of a pressure into the accumulator is limited to the inner wall corner of the accumulator,
The inner wall corner formed at the connection between the plurality of distribution passages and the accumulator can be easily machined at one time. An electrode having a flange portion for closing a part of the opening portion and having a flange portion for forming a flow of the electrolytic solution flowing into the distribution passage through the opening portion is inserted into the pressure accumulating chamber. The electric resistance value between the electrode and the common rail as a conductor, the flow rate and the flow direction of the electrolytic solution are set. The specific flow direction determined by the opening, the flange portion, and the inner wall corner portion is to wrap around the outer edge of the flange portion from the side opposite to the distribution passage side of the flange portion, and the distribution passage side end face of the flange portion and the inner wall corner portion. And a direction in which the air flows around the corner of the inner wall from the annular gap formed therebetween and flows out to the distribution passage. According to the common rail electrolytic processing method according to claim 1, the inner wall corner is formed at the connection part because the inner wall corner is rounded by the electrolytic current in the electrolyte flowing into the distribution passage through the opening by such a flow. The part can be uniformly rounded in the circumferential direction. Further, since the flow rate of the electrolyte flowing out from the plurality of openings is substantially uniform, the plurality of inner wall corners separated from each other can be uniformly rounded.

According to a second aspect of the present invention, the electrode includes a tubular portion provided inside the tubular portion for flowing an electrolytic solution, and an electrode protruding from the outer wall surface of the tubular portion to the opening to form the tubular portion. A neck portion connecting the flange portion and the flange portion; and a hole portion provided on an outer periphery of the neck portion and communicating the inside of the tubular portion with the opening. According to the common rail electrolytic processing method of the second aspect, the electrolytic solution can flow out of the tubular portion inner passage through the hole to the opening, and can flow around the outer edge of the flange portion.

According to a third aspect of the present invention, there is provided a common rail electrolytic processing apparatus having a plurality of openings having an inner diameter larger than the inner diameter of the distribution passage and having a plurality of openings which are in contact with the inner wall forming the pressure accumulating chamber. A conductive member, a conductive portion provided inside the insulating member and partially closing one end of the opening, a neck protruding from the conductive portion to the opening, and a opening formed at the tip of the neck. A flange portion for partially closing and forming a flow of the electrolytic solution flowing into the distribution passage through the opening portion, and a hole portion provided on the outer periphery of the neck portion and penetrating the conductive portion; Is provided.

According to the fourth aspect of the present invention, since the diameter of the flange portion is larger than the diameter of the distribution passage, the annular portion formed between the end surface of the flange portion on the distribution passage side and the corner of the inner wall. The electrolytic solution flowing out of the gap into the distribution passage is removed from the end surface of the flange portion inside the corner portion of the inner wall while being directed radially inward of the end surface of the flange portion on the distribution passage side, so that the surface layer of the corner portion of the inner wall is efficiently removed. Can be rounded.

According to a fifth aspect of the present invention, there is provided a common rail electrolytic processing apparatus, wherein the conductive portion has a mounting hole into which an electrode tip integrally including the flange portion and the neck portion is press-fitted and fixed. Is partially closed to form the hole, so that the flange and the neck can be easily formed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment showing an embodiment of the present invention will be described below. FIG. 1 shows an electrode structure of an electrolytic processing apparatus according to an embodiment of the present invention inserted into a common rail 20. The electrode of the electrolytic processing apparatus includes a cylindrical electrode case 40 having a bottom, a cylindrical electrode pipe 50 inserted into the electrode case 40, and an electrode tip 30 fixed to the electrode pipe 50 by press fitting. I have.

The electrode case 40 corresponding to the insulating member described in the claims is a bottomed cylindrical insulator. The clearance between the inner wall 24 of the common rail 20 forming the accumulator 23 and the outer wall of the electrode case 40 is set such that electrodes can be inserted into and removed from the accumulator 23 in the axial direction. In the side wall of the electrode case 40, the distribution passage 21 at the entrance opening is located at a position facing the entrance opening of the distribution passage 21.
A plurality of circular holes 42 having an inner diameter larger than the inner diameter of the electrode are formed apart from each other in the axial direction of the electrode. The circular hole 42 corresponds to an opening described in the claims.

The electrode pipe 50 corresponding to the conductive portion described in the claims is a tubular conductor inscribed in the electrode case 40. In the present embodiment, since the strength and structure of the electrodes are simplified, the conductive member constituting the circuit leading to the electrode chip 30 is a tubular member inscribed in the electrode case 40. The electrode pipe 50 has a plurality of circular holes 51 for forming the holes described in the claims and for fixing the electrode tips 30. The circular hole 42 and the circular hole 51 are formed coaxially.

FIG. 3 shows an electrode tip 30 corresponding to the electrode tip described in the claims. Electrode tip 30
Is a conductor having a shaft portion 34 and a flange portion 36. The shaft portion 34 has a Y-shaped cross section and has a shape conforming to the original solid when rotated by 120 degrees about the axis. Note that the shape of the shaft portion 34 may be any shape as long as it can be fixed to the circular hole 51 and does not completely close the circular hole 51 when fixed. The outer surface of the shaft portion 34 is a contact portion 37 which is convexly curved in a cylindrical side shape.
And a concave portion 39 which is concavely curved like a ship bottom. Recess 39
The shape is taken into consideration so that the electrode solution hits the concave portion 39 to form a circumferential flow of the electrode solution. In order to press-fit the shaft portion 34 into the circular hole 51 and fix it, the contact portion 37
The diameter of the circle circumscribing the circle is set substantially equal to the diameter of the circular hole 51. A step portion 38 is formed on the shaft portion 34, and the press-fitting depth of the shaft portion 34 is set by bringing the step portion 38 into contact with the outer wall of the electrode pipe 50 as shown in FIG. A gap is provided between the end face 33 and the outer wall surface of the electrode pipe 50. This gap determines the flow rate of the electrolyte.

Shaft 3 from step 38 to flange 36
Reference numeral 4 corresponds to the neck described in the claims. The height from the step portion 38 to the upper end surface 31 of the flange portion 36 is set smaller than the thickness of the side wall of the electrode case 40. By setting the height from the step portion 38 to the upper end surface 31 of the flange portion 36, the distance between the upper end surface 31 of the flange portion 36 and the inner wall surface 24 of the common rail 20 is set. This interval determines the flow rate of the electrolytic solution flowing out of the circular hole 42 into the distribution passage 21 and the resistance value of the electrolytic current. The upper end surface 31 of the flange portion 36 may be convexly curved into a cylindrical side surface so that the distance to the inner wall surface 24 of the common rail 20 is substantially uniform over the entire circumference. The diameter of the flange portion 36 is set to be larger than the diameter of the entrance side opening of the distribution passage 21 of the common rail 20 and smaller than the diameter of the circular hole 42 of the electrode case 40. This is to form a flow of the electrolytic solution indicated by an arrow B in FIG. 4 that goes around the corner 22 formed at the boundary between the wall surface 25 of the distribution passage 21 and the wall surface 24 of the accumulator.

As shown in FIG. 4, when the electrode tip 30 is press-fitted into the electrode pipe 50 and fixed, the concave portion 39 of the electrode tip 30 and the end face 52 forming the circular hole 51 of the electrode pipe 50 are claimed. The described hole is formed. The hole has a leaf shape in cross section, penetrates from the inside to the outside of the electrode pipe 50, and communicates the inside of the electrode pipe 50 with the circular hole 42. The electrode pipe 50 is formed by the sectional area of the hole.
The flow rate of the electrolyte flowing out of the distribution passage 21 is set. The hole is not limited to such a shape.
Any shape may be used as long as it forms a flow in which the electrolyte flows out toward 3. The circular hole 42 is a flange 3 of the electrode tip 30.
6 to form the next remaining space.
That is, a donut having a U-shaped cross section surrounded by the first residual space, the outer wall of the electrode pipe 50, the end surface 41 forming the circular hole 42 of the electrode case 40, and the inner wall surface 24 forming the pressure accumulation chamber 23 of the common rail 20. The second remaining space is a leaf-shaped cross section surrounded by the concave portion 39 of the shaft portion 34 of the electrode tip 30, the end surface 33 of the flange portion 36, and the outer wall of the electrode pipe 50, and is formed at intervals of 120 degrees in the circumferential direction. It is space that is done. The first remaining space communicates with the distribution passage 21 of the common rail 20 when the electrode is inserted into the accumulator. The connecting portion between the first remaining space and the distribution passage 21 is formed in an annular shape. The flow direction and flow rate of the electrode solution are set according to the shape of these residual spaces.

The electrode structure of the common rail electrolytic processing apparatus has been described above. Hereinafter, a description will be given of a common rail electrolytic processing method using the electrolytic processing apparatus according to the present embodiment. As shown in FIG.
0, so that the central axis of the distribution passage 21 of the common rail 20 and the central axes of the circular holes 42 and 51 formed in the electrodes coincide with each other. At this time, the connection portion between the circular hole 42 and the distribution passage 21 is connected to the inner wall corner 22 of the common rail 20.
Is formed annularly in the vicinity of.

An electrolyte such as an aqueous solution of sodium nitrate is supplied to the electrode pipe 50 at a predetermined pressure from a pump (not shown). As shown in FIG. 4, when pressure is applied to the electrolytic solution, the electrolytic solution flows from the inside of the electrode pipe 50 to the distribution passage 21 through the remaining spaces of the circular holes 51 and 42. At this time, due to the substantially uniform pressure in the electrode pipe 50, the electrolytic solution is distributed in the distribution passage 21.
Therefore, the amount of outflow to each of the plurality of distribution passages 21 is substantially equal.

The electrolytic solution flowing out of the remaining space of the circular hole 51 into the circular hole 42 has three leaf-shaped cross sections surrounded by the concave portion 39 of the electrode tip 30, the end surface 33 of the flange portion 36, and the outer wall of the electrode pipe 50. It flows into the remaining space. The flowed electrolytic solution hits the end face 33 of the flange portion 36 and forms a flow that flows radially outward and a flow that flows circumferentially along the curved surface of the concave portion 39. Due to the radial outward flow and the circumferential flow, the flow of the electrolytic solution becomes substantially uniform over the entire circumference of the donut-shaped remaining space having a U-shaped cross section formed around the flange portion 36. That is, as shown by the arrow A in FIG. The flow rate of the liquid becomes substantially uniform in the circumferential direction.

The electrolytic solution that hits the end surface 41 of the electrode case 40 and goes around the flange portion 36 hits the inner wall surface 24 of the common rail 20 and forms a flow along the upper end surface 31 of the flange portion 36. When the electrolytic solution passes through the annular connection portion between the circular hole 42 and the distribution passage 21 along this flow, the cross-section of the flow channel expands to form a flow that goes around the inner wall corner 22 of the common rail. Since the flow rate of the electrolytic solution per unit time passing through the connection between the circular hole 42 and the distribution passage 21 per unit time is substantially uniform in the circumferential direction, the inner wall corner 22
Is substantially uniform in the circumferential direction per unit time.

The potential difference between the electrode tip 30 and the common rail 20 generates an electrolytic current along the flow of the electrolytic solution. Since this electrolytic current flows around the inner wall corner 22 of the common rail 20 along the flow of the electrolytic solution, the surface layer of the inner wall corner 22 is removed and the inner wall corner 22 is rounded.

According to the common rail electrolytic processing apparatus according to the embodiment of the present invention, a plurality of circular holes 51 of the electrode pipe 50 are provided.
Since the flow rate per unit time of the electrolytic solution flowing out from the remaining space to the plurality of distribution passages 21 per unit time is substantially equal, and the flow rate of the electrolytic solution flowing around the inner wall corner 22 is substantially uniform in the circumferential direction, the electrolytic solution is separated from each other. The plurality of inner wall corners 22 can be uniformly rounded at once. In addition, one electrode is connected to the pressure accumulating chamber 2
3, it is enough to easily round a plurality of inner wall corners 22 at one time. In addition, by adjusting the diameter of the circular hole 42, the shape of the electrode tip 30, and the like, the flow direction and the flow rate of the electrolyte flowing around the inner wall corner 22 can be arbitrarily set. Processing becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which an electrode of an electrolytic processing apparatus according to one embodiment of the present invention is inserted into a pressure accumulation chamber of a common rail.

FIG. 2 is a sectional view showing a common rail.

3A and 3B are diagrams showing an electrode tip of the electrolytic processing apparatus according to one embodiment of the present invention, wherein FIG. 3A is a plan view, FIG. 3B is a sectional view, and FIG.

FIG. 4 is a cross-sectional view illustrating an electrolytic processing method according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Injector 20 Common rail 21 Distribution passage 22 Inner wall corner part 23 Accumulation chamber 30 Electrode chip 34 Shaft part 36 Flange part 40 Electrode case 42 Circular hole 50 Electrode pipe 51 Circular hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C059 AA02 AB01 DA07 EC01 ED04 3G066 AA07 AB02 AC07 AD12 BA30 BA48 BA55 CB01

Claims (5)

[Claims] 1. A common rail electrolytic machining method for rounding an inner wall corner forming a connection portion between a plurality of distribution passages for supplying fuel to an injector and a pressure accumulating chamber, wherein the distribution passage communicates with the distribution passage. A cylindrical insulating member having a plurality of openings having an inner diameter larger than the inner diameter of the pressure accumulating chamber and abutting against an inner wall forming the pressure accumulating chamber, and a conductive flange portion partially occupying the opening; Inserting an electrode having a flange portion for forming a flow of the electrolytic solution flowing into the distribution passage into the pressure accumulating chamber; and the inner wall by an electrolytic current in the electrolytic solution flowing into the distribution passage through the opening. A step of rounding a corner portion, wherein the opening, the flange portion, and the inner wall corner portion wrap around the outer edge of the flange portion from the side opposite to the distribution passage of the flange portion and distribute the flange portion. Forming a flow of the electrolytic solution flowing around the inner wall corner from the annular gap formed between the road side end surface and the inner wall corner and flowing out to the distribution passage. Electrolytic processing method. 2. An electrode, comprising: a conductive portion provided inside the insulating member and partially closing one end of the opening; and the conductive portion and the flange protruding from the conductive portion to the opening. The common rail electrolytic processing method according to claim 1, further comprising a neck portion to be connected, and a hole portion opened on an outer periphery of the neck portion and penetrating the conductive portion. 3. A common rail electrolytic processing apparatus for rounding an inner wall corner that forms a connection between a plurality of distribution passages for supplying fuel to an injector and a pressure accumulating chamber, wherein the distribution passage communicates with the distribution passage. A cylindrical insulating member having a plurality of openings having an inner diameter larger than the inner diameter of the pressure accumulating chamber and being in contact with an inner wall forming the pressure accumulation chamber; a conductive member provided inside the insulating member and partially closing one end of the opening; A portion protruding from the conductive portion into the opening; and a conductive flange portion formed at the tip of the neck and partially occupying the opening, and flowing out to the distribution passage through the opening. An electrolytic processing apparatus for a common rail, comprising: a flange portion for forming a flow of a liquid; and a hole portion opened on the outer periphery of the neck portion and penetrating the conductive portion. 4. The common rail electrolytic processing apparatus according to claim 3, wherein a diameter of the flange portion is larger than a diameter of the distribution passage. 5. The conductive portion has a mounting hole into which an electrode tip integrally having the flange portion and the neck portion is press-fitted and fixed, and a part of the mounting hole is closed by the electrode tip so that the hole portion is closed. 5. The common rail electrolytic processing apparatus according to claim 3, wherein the common rail electrolytic processing apparatus is formed.