JPS59209046A - Manufacture of field coil - Google Patents

Abstract

PURPOSE:To improve the reliability of the strength of a field coil and to improve the dimensional accuracy of the coil by sequentially opening the groove of a connector from the inside corner in an oblique shape, and energizing it under pressure. CONSTITUTION:A field coil of a salient pole of a synchronous motor is formed by welding a plurality of conductors 1, 2 of rectangular shape to connecting portions 3. This welding is executed by holding the conductors 1, 2 by a gripper 4, connecting and energizing them with a power source 5, and contacting under pressure by Joule heat of contacting resistance of the portions 3. In this case, the end of the conductor 1 is opened obliquely at the desired angle to the perpendicular surface to the side 16 as further from the inside corner 3a, and perpendicularly butted to form a groove 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a field coil in which a plurality of rectangular electric conductors are connected in a frame shape by voltage contact.

[Technical background of the invention and its problems] Conventionally, field coils with salient magnetic poles in water turbine generators, synchronous motors, etc. have been constructed by using a plurality of strip-shaped electrical conductors such as hard drawn copper strips as shown in Fig. 1. As shown, there are some that are connected like a picture frame. In FIG. 1, (1) is a conductor for end connection, (2) is a conductor for side connection, and (3) is a connection portion.

As a method for manufacturing this frame-shaped field coil, a conductor (1
) and (2) by brazing, arc welding, pressure welding, etc. However, these conventional methods have the following problems.

First, regarding the brazing method: (1) There are many variations in the quality of the connections due to the skill of the worker.

(if) A complex groove shape is required to obtain connection strength.

(1■) It is difficult to automate the connection method, and quality control is also difficult.

and so on. Next, regarding the method using arc welding, (1) Defects are likely to occur at the starting and ending ends.

(11) The thickness of the conductor is limited.

(::i) Especially when cleanliness is required as an electrical conductor, the working environment is limited.

When considering the quality improvement or automation of connection parts, connection by pressure welding has recently become promising, but there are still problems as described below.

In order to explain this problem, first conductors (1), (1
) is connected in a straight line as shown in Figure 2 (a).
.

This will be explained with reference to (b). Two conductors consisting of copper strips (
1), (1) and each conductor (1),
(1) is grabbed by grips (4) and (4), and a power source (5) is connected to both grips (4) and (4).

Then, if the connection part (3) is energized by the power supply (5),
Projection length from grip (4) to connection part (3) 6)
, Joule heat is generated by the electrical resistance of part (7) and the contact electrical resistance of connection part (3), and the temperature IW suitable for pressure welding is achieved.
rise to Immediately after that, pressurization is applied in the pressurizing direction (8) using a hydraulic or pneumatic cylinder (not shown), so that a pressure connection can be achieved. However, in order to form a field coil in a picture frame shape as shown in Figure 2, the end of the end connection conductor (1) is connected to the side surface of the side connection conductor (2), 3) is located at the corner of the picture frame, so the configuration shown in FIG. 3 is obtained. In such a configuration, the connection part (3)
Since the shapes of the conductors (1) and (2) on both sides are asymmetrical, the area near the inner corner part (3a) of the corner contact part (3) is heated due to heat conduction in the longitudinal direction of the side connection conductor (2). The relief is large, so the connection part (3) is connected to the inside corner part (
3a) A thermal imbalance occurs between 1+111 and the opposite outside, so that the inner conductor (1)
, (2) The amount of melt for pressure welding is insufficient, and the pressure welding stress distribution with respect to the pressure force becomes uneven, making pressure welding difficult, or even if pressure welding is possible, the quality of the connection part is uneven. The problem was that I was not satisfied. In particular, if a strong pressure is applied to the inner corner (3a) while it is not sufficiently melted, a notch (9) as shown in Figure 4 will occur, and stress will be concentrated in that part during operation. In order to prevent this, a problem arises in that a finishing process is required to form a rounded portion (10) after pressure welding, as shown in FIG. Therefore, as a countermeasure, the protrusion length 6) and (7) shown in Figure 3 are
It was thought that the conductors (1) and (2) could buckle due to the pressure if the protrusion lengths 6) and (7) were increased, but this would cause problems such as buckling of the conductors (1) and (2) due to the pressurizing force.
Further, there is a problem in that the advantage of the conventional method of secondaryly determining the final dimensions by applying pressure until the grips (4) and (4) come into contact cannot be applied.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a frame-shaped field coil that improves the quality, strength, and reliability of the connection portion.

[Summary of the invention]

In the present invention, in the method for manufacturing a field coil in which a plurality of strip-shaped electric conductors are connected in a frame shape, the connection is made by applying voltage to the corner portions of the frame shape, and the connection portion groove is formed at the inner corner portion. By creating a sloping shape that opens up as it moves away, when electricity is applied to generate Joule heat, the current flow starts melting from the inner corner first, and by integrating the melting, a larger current is concentrated at the inner corner. to ensure melting in that area, and then expand the melted area outwards to avoid notches at the inner corner, homogenize and improve the quality of the connection, and increase strength and reliability. It is.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 6 and 7. Incidentally, a perspective view of the field coil to be manufactured is shown in FIG. 1, so please also refer to this.

The rectangular conductors (1) and (2) are made of hard drawn copper strips, and have a thickness of 511 m, a width of 50 m, and a length including the pressure welding allowance to form a field coil of the desired size. The end ([a) of the end-connecting conductor (1) is located at the inner corner (3a) at an angle α with respect to the perpendicular surface (Ic) to the side surface (16)
), the inclination increases by 1 incline as the distance increases. The side surface (2a) of the side surface connection conductor (2) is rolled to have a uniform plane, and the inner conductors (1) and (2) are abutted at right angles to form a groove αυ as shown in FIG. Note that the angle α of the groove is in the range of 1 to 5 degrees.

Hold the inner conductors (1) and (2) with the tool (4).
, (4) Huge, double-sided grips (4) , <41 A power source that can supply a large current of tens of thousands of amperes and 1,000 liters (5
) to connect. Both force and tools (4) and (4) can be suppressed in the pressing direction (8) and (8) by a pressurizing machine (not shown). (61, (7) are protrusions.

To press from this state, a large current is applied between the protrusions (6) and (7) using the power source (5), and when the heel inner end (3a) starts to melt, the grip tool (4) is pressed using a pressure machine. (4) in the pressing direction (8), (8), and press the end face (1a).
Continue energizing and suppressing until everything is melted and crimped, then stop energizing and suppressing.

Next, the effect will be explained.

Since the side conductors (1) and (2) are in contact only at the inner corner portion (3a) at the start of energization, heat is generated locally in that portion, and melting begins and they are integrated. At this time, the side conductor (1), (
2) is Karo pressure method 1 phrase (8).

(8) When pressed, the contact area becomes wider and the part where the metal phase ζ is completely ignited expands, and the electrical contact resistance approaches zero (nearly zero), so an increasingly large current flows, and the molten part gradually opens outward. 0 ahead
]) is expanded to the tip direction. Here, as a prerequisite, the pressing force in the pressing direction (8), (8) is 1.7, which is applied until the welding is completed by the start of energization and the end of energization.
Needless to say, there is nothing wrong with that. As the distance from the p-i*u corner part (3a) increases, the groove (11) in the shape of an open l/multiple groove (11) is continuously pushed, so that the 3-car melt gradually expands. The melt caused by the swelling of the molten metal can be prevented from falling. Therefore, there is no melting and there is no generation of flash or sparks.
In Q), where melting starts from the corner part (3a), melting in that part is certain, and in Q), where the contact resistance at part 70] becomes close to zero, making it easy for large current to flow, 1. The protrusions (6) and (7) connected to that part are reliably melted by the heat of the seal, and the notches (shown in Fig. 4)
9) can be prevented from occurring and a connection portion with high strength can be obtained. Furthermore, the protrusion length required for pressure welding connections is 6), (force required M'J).
By reducing the limit, the material yield is improved and the dimensional error of the frame-shaped field coil is minimized.
It can be made smaller and the quality is stable.

The groove angle α was set in the range of 1 to 5 degrees because 1
If the groove is smaller than 01), the groove is too close to the groove (9) (see Figure 4),
If the temperature is exceeded, the pressure welding part (6) must be closed, resulting in wasted material, and when welding with voltage, the surface pressure will be lower than the one point, making pressure welding difficult to achieve evenly, and melting will not come off. This is because the harmful effects of flash, sparks, etc. begin to occur.

In the embodiment shown in FIG. 8, when forming the groove (Ll),
A slope (2b) is provided on the side connection side conductor (2).

Even in this case, the same effects as the embodiments shown in FIGS. 6 and 7 can be obtained.

The embodiment shown in FIG. 9 shows a case where there is a part to be connected in a 1-shape, and in this case, the tip of the end connection conductor (1) is opened from both corner parts (3a) by recessing it in a This is the result of forming +13.

Even in this case, the same effects as the embodiments shown in FIGS. 6 and 7 can be obtained.

Note that the present invention is not limited to the embodiments described above and shown in the drawings; for example, the conductor (1).

Of course, (2) can be implemented with various modifications without changing the gist, such as using other materials such as aluminum.

〔Effect of the invention〕

As explained above, according to the present invention, the connection groove is formed into an inclined shape that becomes more open as it goes away from the inner corner, and is energized to make pressure contact with the groove. It has become possible to create pressure-welded connections that do not cause chips, resulting in uniform quality and improved strength and reliability.

(It) By locally generating heat, the amount of deformation of the press-contact portion could be reduced, and the dimensional accuracy of the frame-shaped field coil was improved.

(iii) By locally generating heat, the heating range can be narrowed, and especially when a hard drawn copper strip is used, the area where the strength of the material decreases becomes smaller.

<IV) Because the heat is generated locally, the amount of electricity used can be reduced compared to conventional methods. 7 effects were obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a frame-shaped field coil to be manufactured in an embodiment of the method of the present invention, Fig. 2(a),
(b) is a top view and a vertical cross-sectional view showing conductors arranged abutting each other to make a voltage-carrying connection using the conventional method; A top view showing the state in which the connection is made, Figure 4 is a top view showing the periphery of the connection where the current-carrying connection has been made in the state shown in Figure 3, and Figure 5 is the shape with the notch in Figure 4 removed. FIG. 6 is a top view showing a state in which a groove is formed in the conductor in order to carry out an embodiment of the method of the present invention, and FIG. 7 is a top view showing the conductor shown in FIG. FIGS. 8 and 9 are top views showing the state in which the connection is being made, and FIGS. 8 and 9 are top views showing the vicinity of the groove of the conductor used in other different embodiments, respectively. 1... Conductor for end connection 2... Conductor for side connection 3
...Connection part 3a...Inner corner opening...
Bevel α...Beveling angle Agent Patent attorney Inoue - Man Fig. 1 Fig. 2 Fig. 3

Claims (2)

[Claims] (1) In a method for manufacturing a field coil in which a plurality of strip-shaped electrical conductors are connected in a frame shape, the connection is made by applying voltage to the corners of the frame, and the connection groove is moved away from the inner corner. A method of manufacturing a field coil, characterized in that the field coil is formed into an open inclined shape according to the method. (2) The method for manufacturing a field coil according to claim 1, wherein the groove angle is 1 to 5 degrees.