JP3059374B2 - Manufacturing method of ball joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a holder and a shank with a ball, which are swingably or rotatably connected.
The present invention mainly relates to a method of manufacturing a ball joint used for a link motion mechanism such as a suspension arm section and a steering section of an automobile and a cutting blade driving section of a combine.

[0002]

2. Description of the Related Art Conventionally, a method disclosed in Japanese Patent Publication No. 5-77886 has been known as a method for manufacturing this type of ball joint. In this method, as shown in FIG. 11, a first step of forming a holder 102 by die casting in which a ball 101 is inserted into a mold 100 with a core as a core (separate views a and b), and the holder 102 is wrapped around the first step. The second step (partial views c and d) of forming the shank 104 with a ball by joining the shank 103 to the ball 101 by projection welding, and applying an external force to the shank 104 or the holder 102 with the ball. Ball 101 and holder 10 adhered to each other during casting
And a third step of forming a minute gap between the ball 101 and the second step.
Since the spherical surface is transferred to the holder side, in the ball joint shown in FIG. 12 manufactured by such a method, the ball 101 and the holder 102 are in sliding contact with each other without rattling,
It has the feature of achieving smooth rotation or oscillating movement.

In the first step of this manufacturing method, the ball 101, which becomes a core when the holder 102 is cast, is fixed in the mold 100. Therefore, the ball 101 is sandwiched by a closed mold from above and below. The cast holder 102 has an opening 1 corresponding to the vertical position of the ball 101.
05 and 106 are formed. And
In the second step, projection welding is performed using these openings 105 and 106, and one of the openings 10 is used.
5, the shank 103 is brought into contact with the spherical surface of the ball 101 from the other opening 106, and the electrode 107 through which a welding current is applied is brought into contact with the ball 101.
The projection welding is performed while a predetermined welding current is supplied between the first and third welding processes.

[0004]

When projection welding is performed by directly contacting an electrode with a ball as in this conventional manufacturing method, a sufficiently large contact area between the electrode and the ball must be ensured. For example, there is a fear that a current flow resistance against a welding current is generated between the ball and the electrode, and the ball is melted at the contact position of the electrode. For this reason, it is necessary that the electrode opening formed in the holder has a certain size.

However, since the opening for the electrode is located coaxially with the shank joined to the ball, if the opening for the electrode is made sufficiently large as described above, the shaft of the shank will not be formed. The contact area between the ball and the holder projected along the direction (see FIG. 12 (b)) must be small, and the load capacity of the load (hereinafter, referred to as axial load) acting along the axial direction of the shank. There was a problem that there was a shortage.

On the other hand, in order to increase the axial load capacity without reducing the diameter of the opening for the electrode, the ball diameter must be increased, and the ball joint itself must be increased in size and weight. There was a problem such as becoming.

On the other hand, even if the opening for the electrode formed in the holder is sufficiently large, if the electrode itself does not hit the ball well, a current-carrying resistance also occurs between the electrode and the ball, The ball melts at the contact position of the electrode. For this reason, in the above-mentioned conventional manufacturing method, the electrode made of a copper plate is formed into a spherical surface following the ball spherical surface.
Since the shape of the electrode gradually changes while projection welding is repeated, it is necessary to reshape the electrode every time the welding is performed a predetermined number of times, and production management is very troublesome.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to produce a ball joint having a small ball diameter and a high axial load acting on a shank. It is another object of the present invention to provide a method of manufacturing a ball joint that can perform the production control easily.

[0009]

That is, the present invention relates to a method for manufacturing a ball joint in which a holder and a shank with a ball are swingably or rotationally connected to each other, and a casting mold in which a ball is inserted as a core. A first step of casting a molten metal of a conductive alloy therein, casting a holder that covers the ball while leaving the joint of the shank, and pressing the shank against the ball exposed from the holder, A second step of forming a shank with a ball by projecting a ball and a shank by projecting welding by applying electrodes to each of the electrodes and applying a welding current between the electrodes; and A third step of applying an external force to the ball to form a gap between the ball and the holder. Is shall.

According to the manufacturing method of the present invention, in the second step, a welding current is passed between the shank and the holder via the ball, and the shank is not directly brought into contact with the ball. Since the ball and the ball are joined by projection welding, it is not necessary to provide the holder with an opening for bringing the electrode into contact with the ball. Therefore,
In the first step of casting the holder, it is possible to wrap the ball with a conductive alloy leaving only the joint of the shank, and to produce a ball joint with high load capacity against the axial load acting on the shank. it can.

Even if a welding current is applied between the shank and the holder via the ball, the holder cast in the first step is in close contact with the ball, and the ball is held in the holder. Only the joint of the shank is exposed, so that the ball and the holder have a sufficient contact area. Accordingly, there is almost no current flow resistance to the welding current between the ball and the holder, and only the shank and the ball can be joined by projection welding without welding the ball and the holder.

On the other hand, such a method of the present invention is not limited to a ball joint in which a holder and a shank with a ball are directly connected, but is also applicable to the manufacture of a ball joint in which a holder and a shank with a ball are connected via a bearing bush. Can be applied. That is, a holder having a recessed ball receiving portion for accommodating a ball is manufactured in advance by machining or the like, and the ball is received in the ball receiving portion, and then a molten metal of a conductive alloy is poured into the ball receiving portion. By casting, a bearing bush covering the ball can be cast while leaving only the joint of the shank. Then, while the shank is pressed against the ball exposed from the bearing bush, the electrodes are brought into contact with the shank and the holder, and a welding current is applied between the electrodes, thereby forming the ball and the shank. Can be joined by projection welding to form a shank with a ball.

According to the method of the present invention, a current is again supplied between the shank and the holder after the projection welding is completed, so that the joint between the ball and the shank can be tempered immediately. It is also possible to easily prevent the joint from cracking due to leaving behind.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a ball joint according to the present invention will be described in detail with reference to the accompanying drawings. FIG.
1 shows a first embodiment of a ball joint manufactured by the method of the present invention. In this ball joint, a substantially cylindrical holder 2 is engaged around a ball portion 1a of a shank 1 with a ball, and the ball portion 1a and the holder 2 are brought into sliding contact with each other. On the other hand, the holder 2 is connected so as to swing or rotate freely. FIG. 2 shows an example of the use of this ball joint. A push arm 3 which advances and retreats in the direction of arrow A is locked to the shank 1 with the ball, while an arrow B is attached to the holder. A swing arm 4 swinging along the direction is locked.

The shank 1 with a ball is formed by welding a rod-shaped shank 1b to a steel ball having a high sphericity to be a ball portion 1a, and the shank 1b is tapered so that the push arm 3 is fitted thereto. Is formed, and a male screw 12 is formed at the tip of the mounting portion 11. Accordingly, the push arm 3 is fixed to the tapered mounting portion 11 by screwing the nut 13 into the male screw 12.

On the other hand, the holder 2 is manufactured by die casting, which will be described later, and substantially covers the ball portion 1a except for a joint portion of the shank 1b to the ball portion 1a. A flat portion 20 is formed on the holder 2 at a position opposite to the shank 1b, and the flat portion 20 is used as a contact surface of an electrode at the time of projection welding of the shank 1b described later. A flange 21 for locking the holder 2 to the swing arm 4 is formed on the outer periphery of the holder 2, and an annular groove 22 is formed at a position slightly away from the flange 21. The swing arm 4 is fixed to the holder 2 by fitting a stop ring 23 into the annular groove 22.

A seal member 5 is attached between the outer peripheral edge of the holder 2 and the shank 1b of the shank 1 with a ball, such as grease supplied to the gap between the ball portion 1a and the holder 2. In addition to forming a lubricant pocket 24 for storing lubricant, dust and dirt are prevented from entering the gap from the joint between the ball portion 1a and the shank 1b. Here, the end 5a of the seal member 5 on the shank 1b side is in close contact with the shank 1b by its elasticity, while the end 7b on the holder 2 side is detached from the holder 2 by the swinging or rotating motion of the shank 1 with the ball. It is sandwiched between the outer peripheral edge of the holder 2 and the locking ring so as not to occur.

In the holder 2 of this embodiment, a lubrication port 25 is opened at the center thereof. However, the holder 2 and the ball portion 1 are formed only by the lubricant contained in the lubricant pocket 24.
If it is determined that the lubrication between a and a can be sufficiently performed, it is not sufficient to open the lubrication port 25.

Next, a specific method of manufacturing the ball joint of this embodiment will be described. First, in the first step, the holder is die-cast with a zinc or aluminum-based alloy (for example, one or two JIS zinc alloy die-casts, three, ten, or twelve aluminum alloy die-casts). At the time of such casting, as shown in FIG. 3, a steel ball (ball) 8 serving as a ball portion 1a of the shank 1 with a ball is inserted as a core into a pair of dies 6 and 7 which are divided into upper and lower parts. In this state, the molten metal is pressed into the cavity 9 in the mold. At this time, the position of the inserted steel ball 8 is determined by the support seat 7 a formed in the mold 7, and the inserted steel ball 8 is fixed to the support seat 7 a by a locking rod 6 a protruding from the mold 6. If the steel ball 8 can be securely fixed to the support seat 7a of the mold 7 by a magnetic attraction force or a suction force of a vacuum device, the locking bar 6a of the mold 6 is unnecessary.

Thus, as shown in FIG. 4, the holder 2 in which the steel ball 8 is wrapped with the above alloy is cast,
Is exposed from the holder 2 only at a portion corresponding to the support seat 7a. Further, in this embodiment, since the casting was performed while holding the steel ball 8 with the locking bar 6a, a small hole was opened in the holder 2 also at a portion corresponding to the locking bar 6a.
This hole is used as the lubrication port 25 described above. The flange 21 of the holder 2 is formed by die casting, while the annular groove 22 is formed by machining after die casting.

Next, in the second step, the shank 1b is welded to the steel ball 8 of the holder 2 cast in the previous step. Projection welding is used for this welding. As shown in FIG. 5, the end face of the shank 1b is pressed against the spherical surface of the steel ball 8 exposed from the holder 2 with a predetermined force F, and the holder 2 and the shank 1b are pressed. Each of the electrodes 10a,
10b is brought into contact, and a predetermined welding current is applied between the electrodes 10a and 10b.

Here, an electrode 1 for supplying a welding current is used.
0 a is abutted on the flat portion 20 of the holder 2 without directly abutting on the steel ball 8, and a welding current is indirectly applied to the steel ball 8 via the holder 2. Holder 2
Is in intimate contact with the steel ball 8 when it is cast in the previous process, so that even if a welding current is applied to the steel ball 8 indirectly via the holder 2 in this way, the holder 2 and the steel ball 8 Resistance at the boundary with the
And the steel ball 8 are not welded.

When the projection welding is completed in this way, as shown in FIG. 6, a shank 1 with a ball formed by joining a steel ball 8 held by a holder 2 and a shank 1b is formed, and The ball portion 1a of the shank 1 is cast into the holder 2.

In this step, after the projection welding is completed, a current is applied again with the electrode connected as it is to perform a tempering process on the joint between the steel ball 8 and the shank 1b. This prevents the occurrence of cracks after welding in the part.

Next, in a third step, an external force is applied to the holder 2 or the shank 1 with a ball to form a minute gap between the holder 2 and the ball portion 1a which are still in close contact with each other. The external force may be applied by, for example, tapping the outer periphery of the holder 2 or tapping the shank 1 with a ball in the axial direction to give a slight impact to the ball portion 1a. As a result, the ball portion 1a of the shank with ball 1 comes into sliding contact with the holder 2 freely, and the shank with ball 1 and the holder 2 are connected so as to swing or rotate freely.

Finally, the shank 1b and the holder 2
The ball joint of the present embodiment is completed by mounting the above-described seal member 5 between the outer peripheral edge of the seal member 5 and filling a lubricant such as grease into a lubricant pocket 24 formed by the seal member 5.

The ball joint of this embodiment is manufactured as described above. According to this manufacturing method, the holder 2 and the shank 1b are pressed while the electrode 10 is pressed against the holder 2 in the second step. Since the welding current is supplied between the ball portion and the ball portion, it is not necessary to open an opening for directly contacting the electrode with the steel ball 8 with respect to the holder 2, leaving an extremely small lubrication port 25. 1a can be substantially covered with the holder 2;

For this reason, as shown in FIG. 2, the contact area between the ball portion 1a and the holder 2 is projected along the axial direction of the shank 1 with the ball, and this is compared with the conventional contact area shown in FIG. In view of this, if the diameter of the ball portion 1a is substantially the same, such a contact area is significantly larger in the ball joint of the present embodiment than in the conventional case. Therefore, according to the manufacturing method of the present invention, the load capacity with respect to the axial load along the axial direction of the shank 1 with the ball is greater than that of the conventional manufacturing method in which the electrode opening is always formed in the holder 2. High ball joints can be produced.

Also, since the electrode 10 is pressed against the flat portion 20 of the holder 2 instead of the steel ball 8, it is not necessary to form the electrode 10 into a spherical surface, and the shape of the electrode 10 depends on the number of weldings. There is no need to retouch. Therefore, the production method of the present invention is much easier to control the production than the conventional production method, and is more suitable for mass production of ball joints by automation.

FIG. 7 shows a second embodiment of a ball joint manufactured by the method of the present invention, and shows another example of a ball joint manufactured by the same method as that of the first embodiment. In this ball joint, the shape of the shank 15 with a ball is exactly the same as that of the first embodiment, but the holder 16 is provided with an arm portion 17 that functions similarly to the swing arm 4 described above. Is formed with a female screw 18. still,
The other configuration is the same as that of the first embodiment described above.

FIG. 8 shows a third embodiment of the ball joint manufactured by the method of the present invention. In the ball joint of this embodiment, a ball portion 31a of a shank 31 with a ball and a holder 41 are connected via a bearing bush 50 so as to swing or rotate freely. 31a is cast inside the holder 41.

The shank 31 with a ball is formed by welding a rod-shaped shank 31b to a steel ball having a high sphericity to be a ball portion 31a, just like the first embodiment. Mounting portion 32 and a male screw 33 are formed.

On the other hand, a hole receiving portion 42 having a diameter slightly larger than that of the ball portion 31a is formed in the holder 41 in a concave shape. It is cast by. A flat portion 40 is formed on the holder 41 at a position opposite to the shank 31b.
0 is also used as a contact surface of the electrode at the time of projection welding of the shank 31b. A lubrication port 43 is formed at the center of the holder 41, and a through hole 44 is formed at one place on the outer periphery thereof as a runner for casting the bearing bush 50. Further, a connecting portion 45 is projected from the holder 41, and a male screw 46 is formed in the connecting portion.

The shank 31a and the holder 41
A seal member 51 is attached between the outer peripheral edge of the seal member and the outer peripheral edge of the seal member 51 to form a lubricant pocket 52.

The method of manufacturing the ball joint according to the third embodiment is as follows. First, in the first step, a holder 41 having the hole receiving portion 42, the lubrication port 43, the connecting portion 45, and the like is formed. The formation of the holder 41 may be performed by either machining or forging.

Next, in a second step, the bearing bush is die-cast with a zinc or aluminum-based alloy. At the time of such casting, as shown in FIG. 9, the holder 41 and the ball portion 31a of the shank 31 with the ball are placed in a pair of upper and lower molds 60 and 70.
Insert the steel ball (ball) 80 as the core,
The molten metal is press-fitted into a cavity 90 formed between the ball receiving portion 42 of the holder 41 and the steel ball 80. At this time, the inserted steel ball 80 is held at a predetermined position in the ball receiving portion 42 of the holder 41 by the support seat 71 formed in the mold 70, while the lubrication port 4 of the holder 41 is held.
3 is fixed to the support seat 71 by a locking bar 61 of a mold 60 penetrating therethrough.

As a result, the bearing bush 50 wrapped around the steel ball 80 is cast using the holder 41 as a mold, and the steel ball 80 is exposed from the bearing bush bush 50 and the holder 41 only at a portion corresponding to the support seat 71. .

Next, in the third step, the shank 31b is welded to the steel ball 80 wrapped around the bearing bush 50 in the previous step. For this welding, the same projection welding as that of the first embodiment is used, and as shown in FIG.
1b is pressed against the end face with a predetermined force F, the electrodes 10a and 10b are brought into contact with the holder 41 and the shank 31b, respectively, and a predetermined welding current is applied between the electrodes 10a and 10b.

Also in this embodiment, the electrode 10 abuts on the flat portion 40 of the holder 41 without directly abutting on the steel ball 80, but the bearing bush 50 cast in the previous process is applied to the holder 41 and the steel ball 80. Even if a welding current is applied to the steel ball 80 indirectly through the holder 41 and the bearing bush 50 in this manner, the boundary between the holder 2, the bearing bush 50, and the steel ball 8 is formed. The energization resistance at the portion is extremely small, and the bearing bush 50 does not heat up and weld to the steel ball 80.

When the projection welding is completed in this manner, a shank 31 with a ball is formed by joining the steel ball 80 and the shank 31b held by the holder 41 via the bearing bush 50, and the shank 31 with the ball is formed. The ball portion 31 a of 31 is cast into the holder 41. In the third step, a tempering process can be performed on the joint between the steel ball 80 and the shank 31b by using the same method as in the first embodiment.

Finally, in the fourth step, similarly to the third step of the first embodiment, the holder 41 or the shank 3 with the ball is used.
Holder 4 which is kept in close contact with each other by applying external force to 1
1 and the ball portion 31a, a small gap is formed, and the above-mentioned sealing member 51 is attached between the shank 31b and the outer peripheral edge of the holder 41, and the lubricant is formed in the lubricant pocket 52 formed by the sealing member 51. Fill with a lubricant such as. As a result, the ball portion 31 a of the shank 31 with the ball is formed in the bearing bush 50 cast into the holder 41.
, And the shank 31 with the ball and the holder 41 are connected so as to swing or rotate freely.

Also, in the manufacturing method of the third embodiment, the holder 41 and the shank 31b are pressed while the electrode 10 is pressed against the end face of the holder 41 in the third step.
Since the welding current is supplied between the holder 41 and the bearing bush 50, it is not necessary to open an opening for directly abutting the electrode on the steel ball 08, and the opening against the axial load is accordingly reduced. A ball joint having a high load capacity can be produced.

In this embodiment, since the holder 41 is formed in advance by machining or the like, if a material having excellent mechanical strength is selected as the material of the holder 41, the alloy used for die casting is limited only to the bearing characteristics. It is only required that the alloy is excellent, and there is an advantage that the choice of the alloy is wider than that of the first embodiment.

[0044]

As described above, according to the method for manufacturing a ball joint of the present invention, the shank is projection-welded to the ball cast into the holder by casting, so that the ball is welded in the projection welding. Can indirectly apply a welding current to the ball through the holder, and there is no need to provide an opening in the holder to bring the electrode into contact with the ball, so the axial load acting on the shank is reduced by that much. It is possible to manufacture a ball joint having a high load capacity.

Further, since the electrode used for projection welding is in contact with the holder instead of the ball, if a flat portion for contacting such an electrode is formed in the holder in advance, the conventional method is used. The electrode, which had to be formed in a strictly spherical shape, can be formed in a simple plate shape, and the work of modifying the shape of the electrode during the production of the ball joint is not required. Production management becomes extremely easy, and mass production of ball joints by automating the manufacturing process can be promoted.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a ball joint manufactured by the method of the present invention.

FIG. 2 is a sectional view showing an example of use of the ball joint according to the first embodiment.

FIG. 3 is a view showing a casting process of the holder according to the first embodiment.

FIG. 4 is a sectional view showing a cast holder.

FIG. 5 is a view showing a welding process of a steel ball and a shank cast into a holder.

FIG. 6 is a sectional view showing a shank with a ball joined by welding.

FIG. 7 shows a second embodiment of a ball joint manufactured by the method of the present invention.

FIG. 8 shows a third embodiment of a ball joint manufactured by the method of the present invention.

FIG. 9 is a view illustrating a casting process of the bearing bush according to the second embodiment.

FIG. 10 is a view showing a welding process of a steel ball and a shank cast into a holder and a bearing bush.

FIG. 11 is a process chart showing a conventional ball joint manufacturing method.

FIG. 12 is a cross-sectional view showing a ball joint manufactured by a conventional manufacturing method.

[Explanation of symbols]

1b: shank, 2: holder, 8: steel ball (ball),
10 ... electrodes

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaichi Suga 3-11-6 Nishigotanda, Shinagawa-ku, Tokyo Inside TEIC Corporation (56) Reference JP-A-6-297158 (JP, A) Hei 5-77886 (JP, B2) JP-B-53-8886 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16C 11/06-11/08

Claims (5)

(57) [Claims] 1. A method of manufacturing a ball joint in which a holder and a shank with a ball are swingably or rotatably connected, wherein a molten metal of a conductive alloy is cast into a casting mold in which a ball is inserted as a core. A first step of casting a holder that covers the ball while leaving the joint of the shank; and pressing the shank against the ball exposed from the holder, and bringing the electrode into contact with each of the shank and the holder. A second step of forming a shank with a ball by joining a ball and a shank by projection welding by applying a welding current between these electrodes, and applying an external force to the holder or the shank with a ball, And a third step of forming a gap between the ball joint and the ball joint. Method. 2. A method of manufacturing a ball joint in which a holder and a shank with a ball are swingably or rotatably connected via a bearing bush, wherein the holder includes a recessed ball receiving portion for accommodating the ball. After the ball is received in the ball receiving portion of the holder, a molten metal of a conductive alloy is cast into the ball receiving portion, and a bearing bush that covers the ball except for the joint portion of the shank is cast. A second step of pressing the shank against the ball exposed from the bearing bush, bringing the electrode into contact with each of the shank and the holder, and applying a welding current between the electrodes, thereby forming a ball. A third step of forming a shank with a ball by joining the shank and the shank by projection welding; The external force applied to the shank, the manufacturing method of the ball joint, characterized in that it is composed of a fourth step of forming a gap between the ball and the bearing bush. 3. The method for manufacturing a ball joint according to claim 1, wherein an electric current is applied again between the shank and the holder after the projection welding is completed to temper the joint between the ball and the shank. A method of manufacturing a ball joint. 4. The method of manufacturing a ball joint according to claim 1, wherein in fixing the ball in the casting mold in the first step, a support seat and a locking rod formed in the casting mold are used. A method of manufacturing a ball joint, comprising sandwiching a ball, forming an opening serving as a joining portion of the shank in the holder by the support seat, and forming an oil port of lubricating oil in the holder by the locking rod. . 5. The method for manufacturing a ball joint according to claim 1, wherein a flat portion is formed in the holder, and when the shank and the ball are joined by projection welding, the electrode is formed on the flat portion. A method for producing a ball joint.