JP2613152B2 - Electrostatic machining method and apparatus for stationary blade - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic machining method for machining a stationary vane for a turbine having blade end plates at both ends which are substantially parallel to the moving direction of an electrode, and an apparatus directly used for carrying out the method. It is about.

[0002]

2. Description of the Related Art A stationary blade used in a gas turbine engine or the like generally has a blade end plate at each end of a blade portion of each stationary blade. FIG. 7 is a perspective view showing one vane 1 for a gas turbine. In this figure, reference numeral 2 denotes a wing portion, and reference numerals 3 and 4 denote wing end plates integrally formed at both ends of the wing portion 2.

[0003] Making such a stationary blade by electric discharge machining
Has been performed conventionally. This electrical discharge machining is
Fill between poles with insulating liquid (mainly composed of mineral oil)
Pulse current between the workpiece and the electrode
Process the workpiece into a shape along the electrode surface.
It is. However, this electric discharge machining is extremely slow
There is a problem. Therefore, instead of this electric discharge machining, electrolytic
A construction method has been conventionally proposed. This electrolytic processing is
While flowing the electrolyte between the object and the electrode, the current
(Usually direct current). Here the electrolyte is conductive
Liquid, usually saline, sodium nitrate (NaNO ₃ )
Aqueous solution, potassium nitrate (KNO ₃ ) aqueous solution, etc.
It is.

[0004] In electric discharge machining, machining of a workpiece proceeds, and
As the distance between the workpiece and the electrode increases,
Discharge is less likely to occur. In other words, from a place with a small space
With the progress of electric discharge machining, the entire machining surface of the workpiece is the electrode surface shape
It can be adjusted naturally to conform to the shape. But with electrolytic machining
Does not have such a natural adjustment function, so high machining accuracy
Special considerations are needed to obtain In general, there are many factors related to the accuracy of electrolytic machining, but the most important in relation to the present invention is the relative speed of approach between the electrode and the workpiece. As the approach relative speed increases, the machining gap decreases in inverse proportion to the speed. Therefore, the so-called transfer accuracy is improved.

FIG. 8 shows a state in which the electrode 7 approaches and directly faces a workpiece 1A such as a turbine vane in general electrolytic processing. Here, the traveling direction of the electrode 7 and the surface to be processed are shown. 8 is almost perpendicular. In such a case, both (electrode 7
The so-called machining gap between the workpiece and the surface to be machined 8) is almost constant.

FIG. 9 shows a case where the electrode 7B is processed while approaching the surface 8B to be processed at a certain angle. Angle A between the direction of travel of electrode 7B indicated by the arrow and electrode surface 9
Becomes smaller, the processing gap becomes larger. To the extent, within a certain angle range, the machining gap increases in inverse proportion to the sine of the angle A between the traveling direction of the electrode 7B and the electrode surface 9 (sin A). That is, the angle A of the approach speed to the workpiece 1B.
This is because the vertical vector for is smaller.

FIG. 10 shows wing end plates 3 and 4 at both ends.
FIG. 4 is a view for explaining a processing process of the stationary blade 1 shown in FIG. In this figure, in order to process the wing part 2, an electrode 7 similar to this is used.
C is used. However, the shapes of both ends of the workpiece 1, that is, the shapes of the walls 3A, 4A formed by the blade end plates 3, 4, and the electrodes 7C do not match. In practice, the walls 3A, 4A often form a part of a conical shape, and such a method cannot control the dimensional accuracy at all. The reason is that the sine is close to zero and the gap becomes large, and if this gap exceeds a certain level, it exceeds the range of machining control that is usually considered in electrolytic machining.

[0008]

As described above, in the conventional electrolytic machining, there is a problem that the machining accuracy of the upright walls 3A, 4A of the wing end plates 3, 4, which rise from both edges of the wing portion, becomes low. For this reason, it is necessary to perform finishing using a numerically controlled cutting machine or the like after electrolytic processing, and there has been a problem that productivity is poor.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has both ends of a wing portion substantially orthogonal to the direction of electrode travel.
It is a first object of the present invention to provide an electrolytic processing method capable of processing a stationary blade having a blade end plate at high accuracy. It is a second object to provide an apparatus that can be used directly to perform this method.

[0010]

According to the present invention, a first object is to make an electrolyte flow between an electrode and a conductive stationary blade having a blade end plate at both ends of a blade portion. The electrode is placed almost directly on the wing
In the electrolytic processing method of the stator vane to approach in the intersecting direction,
Allowing the electrode to expand and contract in a direction substantially parallel to the wing,
In the early stage of electrolytic machining, the electrode is reduced to increase the gap between the opposing blade end plates, and during the electrolytic machining, the electrode is gradually extended to gradually reduce the gap with the blade end plate. This is achieved by a method for electrolytically machining a stationary blade characterized by the following. The second object is, while flowing an electrolyte solution between the conductive vanes and the electrode having a tip plate on both ends of the wings, substantially perpendicular to the electrode on the blade unit relative to the stationary blade
The electrode is provided with a plurality of end electrodes opposed to the blade end plate and slidably in contact with these end electrodes on inclined surfaces respectively.
An intermediate electrode that is substantially inverted trapezoidal on a side cross section in a plane substantially parallel to the part, and at the end of processing, the intermediate electrode is advanced relatively late with respect to the end electrode during the initial stage of processing and on the way. An electrode feed mechanism for making the electrode surfaces of the intermediate electrode and the end electrode substantially continuous is provided by a stationary blade electrolytic processing apparatus.

[0011]

FIG. 1 is a side view of an electrode 70 for illustrating a basic concept of the present invention, showing an initial stage or an intermediate stage of processing. FIG. 2 also shows the state at the end of the processing. The electrode 70 is divided into three parts 71, 72, 73. The intermediate electrode 72 has a wedge shape or an inverted trapezoidal shape, and is located between the end electrodes 71 and 73 having an angle corresponding thereto. The intermediate electrode 72 and the end electrodes 71 and 73 are slidably adhered on the inclined surfaces P and Q. FIG. 1 shows a state in which the intermediate electrode 72 slightly floats from the electrode bottom surface. In FIG. 2, 3
The three electrodes 71, 72 and 73 are aligned and indicate that they are at the processing end position.

As is clear from FIGS. 1 and 2, the total length of the combined electrode is longer in FIG. 2, and the end electrodes 71, 73 are used in the process from FIG. 1 to FIG. This produces a relative velocity in the direction perpendicular to the walls 3A, 4A of the plates 3,4. The required movement amount of the end electrodes 71 and 73 is the wall 3A,
It depends on the height of 4A, but generally 2 to 4 on one side
Millimeters. As a result, the shapes of the wing end plates 3 and 4 are accurately transferred from the electrode 70.

FIGS. 3 and 4 are a front sectional view and a side sectional view of the entire electrode section including an electrode feed mechanism for causing the electrodes 70 to move mutually. These mechanisms are merely examples for the purpose of understanding the present invention, and even if a different mechanism can be used, as long as the concept of the electrode falls within the scope of the claims, it is included in the present patent. is there.

In FIG. 3, the entire mechanism is stored in a mechanism storage section indicated by reference numeral 30. The housing 30 is mainly made of reinforced plastic to protect against electrical effects and erosion by the electrolyte. There are also a plurality of bolt holes 32 provided on the protrusion 31 of the storage unit 30 for mounting the storage unit 30 on a ram (electrode mounting plate, not shown). A shaft 34 is provided in the storage unit 30 in parallel with the mounting surface 33, and is fixed by two support portions 35 provided on the wall surface of the storage unit 30. This shaft 34
The eccentric cam 36 for moving the intermediate electrode 72 up and down in FIG.

End electrodes 71 and 73 are provided on both sides of the cam 36.
Screw cams 37, 38 having female grooves 37A, 38A for moving the right and left are mounted. The cam grooves 37A and 38A are provided on the base plates 39 of the end electrodes 71 and 73,
40 are fitted with the male blocks 41, 42 attached to the shaft 40.
By the rotation of 4, the end electrode 71 moves to the left in the drawing, and the end electrode 73 moves to the right in the drawing.

Between the base plates 39, 40 and the storage unit 30, linear bearings 43, 44 with slide blocks are provided at positions not interfering with the male blocks 41, 42. There is a bearing 43 between the storage unit 30 and a bearing 44 between the base plate 40 of the end electrode 73 and the storage unit. The respective end electrodes 71, 73 are fixed to the slide blocks 45, 46 of the respective linear bearings via the base plates 39, 40.

The rail portion of the linear bearing has a housing 3
0 on the axis (parallel to the paper surface)
0, the end electrodes 71, 73 slide freely. In practice, the sliding distance is on the order of 5 mm per side, and does not require much space. Cable joints 61 and 63 for applying a cathode potential to the end electrodes 71 and 73 are provided on the end electrodes 71 and 73, and another cable joint (not shown) is provided on the intermediate electrode 72. ing.

As a driving power for the shaft 34, there is a stepping motor 50 fixed to the storage section 30 and fitted to the shaft 34. Instructions to start and stop driving the motor 50 are automatically given by a ram position shown on an operation panel (not shown) of the machine main body. In addition, the stepping motor returns to the original position in response to the electrical signal indicating the end of processing. The intermediate electrode 72 is provided with pulling springs 65 and 6.
6 returns to the original position. One end of the spring is an intermediate electrode 7
2, the other end is fixed to an appropriate position of the storage unit 30. The end electrodes 71 and 73 have stoppers at their most widened positions.
51 and 52 prevent excessive enlargement.

In FIG. 4, the disc-shaped cam 36 fixed to the shaft 34 pushes down the intermediate electrode 72 with the rotation of the stepping motor so that the processing surfaces of the electrodes 71, 72, 73 coincide at the end point. It is adjusted to. As shown in FIG. 5, three electrodes 71, 72,
In order to make sure that 73 is always on the same axis, the fitting groove 53
A, 53B. As shown in FIG. 6, the electrodes 70 are arranged on both sides of the wing portion 2 which is the workpiece 1, and are used to simultaneously process the wing portion 2 from both sides. Here, the approach speed of the intermediate electrode 72 to the workpiece 1 is desirably higher than the approach speed of the end electrodes 71, 73 to the walls 3A, 4A. The electrode 70 may be divided into three or more parts.

[0020]

According to the first aspect of the present invention, as described above ,
And retractable in a direction substantially parallel to the wings of the stationary blade, the electrode (70) in the electrolytic processing early stationary blade substantially parallel to the wing portions
The electrode 70 and the wing part during the processing
Since the electrolytic machining is performed while extending in the parallel direction, a relative motion is generated between the electrode and the wall of the blade end plate, thereby enabling accurate machining of the wall. For this reason, machining after electrolytic machining becomes unnecessary or the amount of machining can be reduced. According to the second aspect of the present invention, there is provided an apparatus directly used for performing the method.

[Brief description of the drawings]

FIG. 1 is a conceptual view of the present invention showing a state in the middle of processing.

FIG. 2 is a conceptual diagram of the present invention showing the end of processing.

FIG. 3 is a front sectional view of the processing apparatus.

FIG. 4 is a side sectional view of a processing apparatus.

FIG. 5 is a perspective view showing the structure of an electrode.

FIG. 6 shows an example of use.

FIG. 7 is an example perspective view of a stationary blade.

FIG. 8 is an explanatory view of a conventional processing method.

FIG. 9 is an explanatory view of a conventional processing method.

FIG. 10 is an explanatory view of a conventional processing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator blade 3, 4 Blade end plate 3A, 4A Wall 70 Electrode 71, 73 End electrode 72 Intermediate electrode

Claims (2)

(57) [Claims] 1. A while flowing an electrolyte solution between the two ends and the conductive vanes having a blade end plate to the electrode of the wings, close to the direction substantially perpendicular to the electrode on the blade unit relative to the stationary blade In the electrolytic processing method for a stationary blade to be performed, the electrode can be expanded and contracted in a direction substantially parallel to the wing portion, and the electrode is reduced in an initial stage of the electrolytic processing so that a gap between the electrode and the facing blade end plate is reduced. And the gap between the electrode and the blade tip plate is gradually reduced during the electrolytic processing to gradually reduce the gap between the electrode and the blade end plate. Wherein while flowing an electrolyte solution between the two ends and the conductive vanes having a blade end plate to the electrode of the wings, close to the direction substantially perpendicular to the electrode on the blade unit relative to the stationary blade In the electrostatic blade machining apparatus, the electrode is a plurality of end electrodes facing the blade end plate, and a surface substantially slidably adhered to each of the end electrodes on an inclined surface and substantially parallel to the blade portion. An intermediate electrode having a substantially inverted trapezoidal shape on the side cross-section at the time of machining, and the intermediate electrode is advanced relatively late with respect to the end electrode at the beginning and during machining, while the intermediate electrode and the end portion are advanced at the end of machining. An electrolytic processing apparatus for a stationary vane, comprising: an electrode feed mechanism for making an electrode surface of an electrode substantially continuous.