JPH09225645A - Method for joining metallic ball - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic ball joining method capable of welding a spherical object to an object with a receiving part highly accurately without being affected by the deviation of a relative position between an upper electrode and a lower electrode. SOLUTION: This joining method is such that a shaft with a receiving part S1 is placed on a lower electrode 2, that a flat circular recessed part 1a is formed on the lower face of the upper electrode 1, that a ball C is positioned on the receiving part S1 of the shaft, that conductive thin copper foil 3 is arranged between the ball C and the upper electrode 1, and that the upper and the lower electrodes 1, 2 are energized with a pressurizing force applied to the copper foil 3, the ball C and the shaft S by means of these electrodes 1, 2. The ball C and the shaft S are pressurized while the copper foil 3 is elastically and plastically deformed to the extent that the copper foil 3 is prevented from coming into contact with the inner surface of the recessed part 1a of the upper electrode 1; and then the ball C and the shaft S are joined with each other through the energization between the upper and lower electrodes 1, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal ball joining method for joining a spherical article to be joined on a article having a receiving portion by electric resistance heating such as welding or resistance brazing.

[0002]

2. Description of the Related Art For example, when a sphere made of a conductive metal is welded to a receiving part of a work made of a conductive metal having a receiving part by electric resistance welding, conventionally, a sphere is formed between an upper electrode and a lower electrode. Welding is performed by arranging works and energizing them while applying pressure so as to sandwich both works between the upper electrode and the lower electrode.

However, since the Joule heat generated at the place where the upper electrode and the sphere are in direct contact is large, the deterioration of the material of the sphere due to the heat input has been a problem.

[0004]

SUMMARY OF THE INVENTION Conventionally, the special table 2
According to Japanese Patent Laid-Open No. 503294, a thin soft conductive metal plate such as a copper alloy is interposed between an upper electrode and a sphere, and the soft conductive metal plate is sandwiched so that pressure is applied between both electrodes to conduct electricity.
A method of welding was proposed. In this welding method, as shown in FIG. 5, a workpiece 10 having a receiving portion 10a is attached to a lower electrode 1
4, the ball 11 is placed on the receiving portion 10a thereof, and the upper electrode 13 having the concave portion 13a is lowered with the metal plate 12 interposed therebetween, and the metal plate 12 is lowered by this lowering. Is deformed along the surface of the sphere 11, the sphere 11 is made to enter the recess 13a, and welding is performed while applying pressure from above and below while the sphere 11 is in contact with the inner surface of the recess 13a via the metal plate 12.

Therefore, when the relative positions of the upper electrode 13 and the lower electrode 14 are misaligned as shown in FIG. 5, (generally, the positional accuracy of the upper and lower electrodes of the resistance welding machine depends on the accuracy of the work formed by cutting. The joint accuracy between the sphere 11 and the work 10 is considerably lower than that of the other, and the joint accuracy between the sphere 11 and the work 10 deteriorates depending on the relative positional deviation between the upper electrode 13 and the lower electrode 14 (poor position accuracy), and the joint between the sphere and the work is improved. There was a problem that it could not be done accurately.

The present invention has been made in view of the above points, and accurately joins a spherical article to be joined and a article having a receiving portion without affecting the displacement of the relative positions of the upper electrode and the lower electrode. It is an object of the present invention to provide a method for joining metal balls that can be used.

[0007]

According to the bonding method of the present invention for solving the above problems, a metal plate is bonded to an object to be bonded while elastically and plastically deforming the metal plate within a range in which the metal plate does not come into contact with the inner surface of the recess of the upper electrode. An object is pressed and an electric current is applied between the upper electrode and the lower electrode to bond the object to be bonded and the object to be bonded.

In the metal ball bonding method having such a structure, even if the axial center positions of the upper electrode and the lower electrode are deviated, the object to be bonded is pressed downward through the metal plate material, and the inner surface of the recess of the upper electrode is pressed. Since they do not come into contact with each other, they are not affected by the displacement of the axial center position. For this reason, even when using a joining device with poor positional accuracy of the upper electrode and the lower electrode, the joining position of the article to be joined and the article to be joined can be accurately measured without being affected by the poor position accuracy. It can be held and joined by electric resistance heating.

Here, in order to press and hold the article to be joined and the article to be joined while elastically and plastically deforming the metal plate material within a range in which the metal plate material is not brought into contact with the inner surface of the depression of the upper electrode, the inner diameter of the recess of the upper electrode is held. a (mm), the thickness t (mm) of the metal plate material, the pressing force W (kgF) applied between the objects to be joined, and the diameter L (mm) of the objects to be joined are expressed by the following equation (1). It is effective to set so as to satisfy (2).

T ³ / a ² > (1.3 × 10 ⁻⁵ ) / W (1) a> L + 2t (2) The joining method may be resistance welding or resistance brazing.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 uses an upper electrode 1 and a lower electrode 2,
The sectional view at the time of performing electrical resistance welding of the ball C of the article to be joined onto the shaft S of the article to be joined is shown. The upper electrode 1 is formed in a cylindrical shape, and has a planar circular recess 1a on its lower surface.
Is formed and attached to a lifting device (not shown),
It can be moved up and down.

The lower electrode 2 is disposed below the upper electrode 1 so as to face it, and a hole 2a for mounting the shaft S of the joined object is provided at the center of the lower electrode 2. The shaft S has a flange portion S2 at an intermediate portion of a round bar, and the flange portion S2 is placed on the lower electrode 2 with the upper surface of the lower electrode 2 being brought into contact with the lower electrode 2.
Further, a concave receiving portion S1 for receiving the sphere C is formed at the upper end of the shaft S.

The upper electrode 1 and the lower electrode 2 are made of a conductive hard metal such as chromium copper or beryllium copper, and the ball C of the object to be joined and the shaft S of the object to be joined are made of a conductive metal such as copper or iron. Are formed in the above shape by their alloys. Reference numeral 3 denotes a copper foil that serves as a metal plate material, which is inserted between the upper electrode 1 and the sphere C during welding and contacts the lower surface of the upper electrode 1 as shown in FIG. 1 and is horizontal without applying tension. It is held by a holder (not shown) so as to move up and down together with the upper electrode 1 while maintaining the state.

By the way, the inner diameter of the concave portion 1a of the upper electrode 1, the thickness of the copper foil 3, the pressing force applied between the sphere C and the shaft S, and the diameter of the sphere C are set such that when the copper foil 3 is welded to the upper electrode, 1
It is set so as to satisfy the following formulas (1) and (2) so that the copper foil 3 is pressed while elastically and deformed to be welded within a range where it does not come into contact with the inner surface of the concave portion 1a.

T ³ / a ² > (1.3 × 10 ⁻⁵ ) / W (1) a> L + 2t (2) where a is the inner diameter (mm) of the recess 1 a of the upper electrode 1, and t is the copper foil. 3, W is a pressing force (kgF) applied between the ball C and the shaft S, and L is a diameter (mm) of the ball C.

In the above formula (1), when a pressing force is applied to the center of the peripheral restraint disc (copper foil), the disc is deformed, and the deformation amount does not exceed a predetermined amount. When the condition of the above formula (1) is exceeded, the copper foil 3 is destroyed at the time of pressing, or the copper foil 3 is largely deformed and the sphere C moves upwards through the copper foil 3. The inner surface of the recess 1a of the electrode 1 will come into contact. The above (2) is the sphere C
Sets a range within which the copper foil 3 and the copper foil 3 can enter the recess 1a of the upper electrode 1.

A welding power source 4 for supplying a predetermined welding current is connected between the upper electrode 1 and the lower electrode 2 via a switch 5.

Next, a method of welding the sphere C and the shaft S using the above welding apparatus will be described. First, the shaft S of the jointed object is inserted into the hole 2a of the lower electrode 2 and vertically on the lower electrode. At the same time as the installation, the sphere C of the article to be joined is placed on the recess S1 on the upper surface of the shaft S (FIG. 1).

Then, an elevating device (not shown) is driven to lower the upper electrode 1 together with the copper foil 3 toward the lower electrode 2, and the copper foil 3 is pressed onto the ball C with a pressing force W. At this time, the copper foil 3 is elastically and plastically deformed as shown in FIG. 2, and the position where the pressing force W and the holding force due to the deformation of the copper foil 3 are balanced, that is, the sphere C is located in the recess 1 a via the copper foil 3. It stands still without touching the inner surface.

At this time, if the axial center positions of the upper electrode 1 and the lower electrode 2 are completely coincident with each other as shown in FIG. 2, the sphere C is naturally held accurately at the center position on the shaft S. For example,
As shown in FIG. 3, even if the axial center positions of the upper electrode 1 and the lower electrode 2 are deviated, the sphere C is pressed downward through the copper foil 3 and does not come into contact with the inner surface of the concave portion 1a of the upper electrode 1. Therefore, it is not affected by the shift of the axial center position.

Therefore, even when welding is performed using a welding device in which the positional accuracy of the upper electrode 1 and the lower electrode 2 is poor,
Sphere C with high accuracy without being affected by the poor position accuracy
The welding position of the shaft S can be held.

In this state, the switch 5 is turned on to energize the welding power source 4 between the upper electrode 1 and the lower electrode 2, whereby Joule heat generated at the contact portion between the ball C and the shaft S causes the contact portion to move. It melts and the ball C and the shaft S are welded.

In this way, regardless of the positional accuracy of the upper and lower electrodes 1 and 2, the welding can be performed while maintaining the welding position of the ball C and the shaft S with a high degree of accuracy. Can be accurately welded.

In the above embodiment, the case of welding is explained, but the ball C and the shaft S are made by the resistance brazing method.
The present invention can also be applied to the case of joining.
When the sphere C and the shaft S are joined by this resistance brazing method, the sphere C is placed on the shaft S via the brazing material 7 as shown in FIG. 4, and the brazing power supply is provided between the upper electrode 1 and the lower electrode 2. 8 is connected, a brazing current is supplied to melt the brazing filler metal 7 by Joule heat, and the sphere C and the shaft S are joined by brazing. Both can be joined together.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of an initial set state of welding showing an embodiment of the present invention.

FIG. 2 is a cross-sectional explanatory view at the time of welding.

FIG. 3 is a cross-sectional explanatory view at the time of welding in which the axial center positions of the upper and lower electrodes are misaligned.

FIG. 4 is a cross-sectional explanatory view of an initial setting state of brazing showing another embodiment.

FIG. 5 is a cross-sectional explanatory view at the time of conventional welding.

[Explanation of symbols]

 1-Upper electrode 1a-Recessed part 2-Lower electrode 3-Copper foil C-Sphere (joined object) S-Shaft (joined object) S1-Receiving part

Claims (4)

[Claims] 1. A bonded article having a receiving portion is placed on the lower electrode, a flat circular recess is formed on the lower surface of the upper electrode, and a spherical article to be bonded is positioned on the receiving section of the bonded article. While disposing a conductive thin metal plate between the article to be joined and the upper electrode, and applying a pressing force between the metal plate, the article to be joined and the article to be joined by the upper electrode and the lower electrode, In a joining method of welding and joining by energizing between the upper electrode and the lower electrode, the metal plate material presses the article to be joined and the article to be joined within a range in which the metal plate material is not brought into contact with the inner surface of the recess of the upper electrode. A method for joining metal balls, characterized in that an electric current is applied between the upper electrode and the lower electrode to join the article to be joined and the article to be joined. 2. The inner diameter a (mm) of the contact portion of the recess of the upper electrode with the metal plate material, the thickness t (mm) of the metal plate material, and the pressing force W (which is applied between the object to be bonded and the object to be bonded) kgF) and the diameter L (mm) of the spherical object to be bonded are expressed by the following equations (1) and (2).
The method for joining metal balls according to claim 1, wherein the method is set to satisfy the above condition. t ³ / a ² > (1.3 × 10 ⁻⁵ ) / W (1) a> L + 2t (2) 3. The metal ball joining method according to claim 1, wherein resistance brazing is performed by interposing a brazing material between the article to be joined and the article to be joined. 4. The metal ball joining method according to claim 1, wherein the article to be joined and the article to be joined are pressed by a pressing force due to elasticity or plastic deformation of the metal plate material.