GB2207951A

GB2207951A - Ball joint

Info

Publication number: GB2207951A
Application number: GB08719119A
Authority: GB
Inventors: Hiroshi Teramachi
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-08-12
Filing date: 1987-08-12
Publication date: 1989-02-15
Anticipated expiration: 2007-08-12
Also published as: FR2619425B1; FR2619425A1; DE3726863A1; GB2207951B; GB8719119D0

Description

1 - MH 52-036 "Ball JoinC 2 cl U- r/ 19 b 1 0 This invention relates to a

ball joint and to a method of manufacturing the same, and in particular to a ball joint and a method of manufacturing the 1 same having an oil reservoir at the bottom portion of a ball receiving portion of a holder for the purpose of obtaining smooth movement.

A known type of such a ball joint is that comprising a holder having a ball receiving portion at one end and a connecting portion at the other end, a ball member one end thereof having a ball which is rotatably and movably held in the ball receiving portion of the holder and the other end having a connecting portion, and a sealing member which is secured to the portion between the ball receiving portion and a base portion of the connecting portion of the ball and rod, and which accommodates lubricant such as grease which is supplied betwen the spherical body or ball and the ball receiving portion and which also prevents entrance of dust and so forth into the portion between this spherical body and the receiving portion (for example: Japanese Patent Publication No. 26109/1973).

A - known method of manufacturing such a ball joint is, for example, that a ball is set as a core in a die for a holder. A die cast fusible alloy is cast into this die so as to cast the holder in which the ball is held in a ball receiving portion. The ball which is held by the holder, and the main body of a rod are welded together by friction welding.

A ball member in which a ball thereof is held by the holder is thus formed. Then an external force is applied between the ball receiving portion of the holder and the ball so as to form a clearance to produce a finished ball joint (Japanese Patent Application No. 11002/1972).

In this method, a ball having a smooth surface and high sphericity can be used to form the spherical ball portion of the ball member.Furthermore, the ball receiving portion of the holder can be cast with this ball used as a core. As a result of this, this method has an advantage that a hard chill layer can be formed on the inner surface of the ball receiving portion.

In the ball joint, described hereinbefore, however, it is necessary that the clearance between the ball and ball receiving portion is as small as possible. The reason for this is that a large clearance between the ball and the receiving portion may cause the receiving portion of the holder to be broken if an impacting load is applied therebetween. Furthermore, if the lubricant which is supplied. between the ball and the receiving portion has a high viscosity, such as-grease, the lubricant enclosed by the sealing member cannot be introduced sufficiently. As a result of which, the lubricant cannot be efficiently supplied to the whole portion covering the ball and the receiving portion, which can, cause a seizure or the like during high speed operation and so forth.

In the aforesaid manufacturing method, there is no way to fix the ball which is used as a core in the die for casting the holder. The ball therefore sometimes moves by the-flow of the die-cast fusible alloy when the die-cast is cast into the die for casting the holder, which leads a defective article. Furthermore, considerable skill is needed to cast this die-cast fusible alloy, which therefore raises a problem with regard to productivity.

In this conventional manufacturing method, the ball member is formed by welding the ball and the main body of a rod by the following method. The two parts are brought into contact with each other and they are relatively rotated under pressure I with the frictional heat that this generates welding the parts together. The pressure applied at the time of frictional welding to the ball and the main body of the rod is extremely high. As a result of this high pressure and high frictional heat which are applied to the ball at the time of the frictional welding, the sphericity of the ball deteriorates. After it has become a ball and rod, the sphericity of the ball is poor, and the high sphericity with which the ball was originally provided loses its meaning. Further, this results in the necessity of providing a large clearance between this ball and the ball receiving portion of the holder which rotatably and movably accommodates the spherical body, the clearance compensating for the difference between the maximum and the minimum diameter of the ball. In order to form this large clearance, a large force is applied to the ball and the receiving portion, which can lead to a breakage of the receiving portion. Furthermore, in the case where a plurality of the parts are combined to form a link mechanism, the error caused by the large clearance between the aforesaid ball and the receiving portion accumulates which leads to the accuracy in conducting force and so forth to be deteriorated. If the deterioration in sphericity in the ball becomes too large, beyond tolerances, it can cause a large impacting force to be applied between the two parts at the time of use, and can cause the cast receiving portion of the holder to be broken. Furthermore, in the case where the ball and rod is formed by friction welding, the tempering process after the welding must be caried out separately. Furthermore, long time leaving the welded parts for a long time before tempering causes a so-called delayed crack to occur in the weld. The tempering must be, therefore, applied as soon as possible, and deburring is needed in - 4 the welded portion. AS a result of this, the manufacturing process is thus restricted.

Viewed from one broad aspect there is herein provided a method of forming a ball joint comprising, placing a ball in a holder die defined by two die members, said ball being supported by a supporting portion of one of said die members, casting the holder by pouring a metal into said die whereby a receiving portion of said holder is defined about said ball and said receiving portion has an opening formed by said supporting portion, and removing the cast holder and ball from said die.

Viewed from another broad aspect there is herein provided a ball joint comprising, a holder having a ball receiving portion at one end thereof and a connecting portion at the other end, and a ball member having a ball at one end thereof and a connecting portion at the other end, said ball being rotatably held in said ball receiving portion, wherein said ball receiving portion is provided with an opening at a position remote from the connecting portion of said ball member and said opening is closed by means of a cover member so as to define an oil reservoir.

At least in preferred forms there is provided a ball joint having an oil basin or reservoir at the bottom portion of the ball receiving portion of the holder, and which can smoothly rotate and move. Furthermore the ball of the ball member may have high sphericity, as a result of which, the clearance between the ball and the receiving portion of the holder which accommodates this ball can be made small. The shakiness between the two parts is prevented so as to make the rotation and movement smooth. Furthermore, no large impacting load is applied between these parts during the use.

1 S ji 1 Furthermore, in preferred forms, there is provided a ball joint having an oil reservoir which is formed by forming an opening at the bottom portion of the ball receiving portion of the holder and securing a cover member to this opening from outside. The opening is formed by a ball supporting portion of the die which is used to fix the aforesaid ball at the time of casting the holder with the ball which forms the ball member as-a core.

Preferably the holder is formed with the receiving portion thereof- having an opening facing substantially at right angles with respect to the connecting portion. The connecting portions which are respectively provided for the aforesaid holder and the ball member may be means which can connect with other members such as outer threads or inner threads. Preferably both connecting portions are in the form of roOs, one having an external thread and the other an internal thread.

The diameter of the opening which is formed in the bottom portion of the receiving portion of the holder preferably is substantially the same as or larger than the diameter of the connecting portion of the ball member. The opening can be thus used as an entrance of a supporting electrode which supports the aforesaid spherical body at the time of joining by projection welding the ball cast in the holder and the main body of the rod which forms the connecting portion of the ball member.

Furthermorey thanks to manufacturing the ball member by projection welding the main body of the rod and the ball the sphericity of the ball can be increased. That is, when projection welding the ball and the main body of the rod, the diameter of the opening which is formed by the ball supporting portion in the die is substantially the same as or larger than the diameter of the main body of the rod, the diameter of the supporting electrode which supports the ball by inserting into the opening and which becomes one side electrode at the time of projection welding can be substantially the same as or larger than the diameter of the aforesaid main body of the rod. As a result of this, electric current can be concentrated into the portion between the ball and the main body of the rod at the time of projection welding, and the welding in this portion can be performed efficiently. And simultaneously, the portion of the ball in contact with the supporting portion of the supporting electrode can keep its surface smoothness and sphericity and so forth.

The means for fixing a cover member which forms an oil reservoir which is formed in the botttom portion of the receiving portion of the holder may be that an annular projection is formed in the circumference of the edge of the opening to which this cover member is fixed for the purpose of caulking the annular projection.

The projection welding may be a laminated projection welding and so forth, preferably a butt projection welding. The employment of the projection welding can decrease weld burrs, the deburring process by cutting the burrs and so forth is therefore unnecessary. Furthermore, tempering of the welded portion can be easily performed by passing electric current again in the state after projection welding the ball and the main body of the rod. As a result of this, a so-called delayed crack which can occur in the welded portion of, for example, hard carbon steel by leaving the tempering for a long time after welding can be completely prevented by carrying out tempering immediately after the welding.

Since the ball joint has an oil reservoir in the bottom portion of the receiving portion of the holder, from which lubricant such as grease is supplied from both the upper and lower portions - 7 of the portion between the ball of the ball member and the receiving portion of the holder, the lubricant can be fed smoothly. The lubricant can be thus efficiently supplied to the portion between this ball and the receiving portion. Thanks to this efficient supply of the lubricant. smooth rotation and movement can be achieved even at high speed operation and so forth without problems such as seizuring and so forth.

Furthermore, since the ball used as a core is fixed between one die member and the ball supporting portion which is provided for the other die member, the ball can be prevented from runout by the cast die-cast fusible alloy, thanks to which, defects can be prevented from generation. Since the ball and the main body of the rod are joined by projection welding, a ball member with the use of a ball displaying a high sphericity can be manufactured without any deterioration in its sphericity. Furthermore, the receiving portion of the holder is cast with the use of this ball having high sphericity as a core, the clearance between the receiving portion and the ball can be arranged as minimum as possible to meet requirements. As a result of which a large impacting force can be thus prevented during usage, and a ball joint displaying large durability can be thus manufactured. An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:Figure 1 is a cross sectional view illustrating ball joint of an embodiment of the present invention; Figure 2 is a left side view of Figure 1; Figure 3 is a right side view of Figure 1; 35 Figure 4 illustrates a method of manufacturing holder with a ball used as a core; Figure 5 is a partial cross sectional view illustrating the holder in which the ball is cast; - 8 Figure 6 is a right side view of Figure 5; Figure 7 is a plan view of Figure 5; Figure 8 illustrates a method of joining a ball which is cast in a holder and a main body 5 of a rod by projection welding; and Figure 9 is a cross-sectional view illustrating a ball and rod and a holder which are formed by projection welding shown in Figure 8.

Figures 1 to 3 illustrate a ball joint of one embodiment of the present invention. The ball joint comprises a holder 1 having a spherical ball receiving portion 2 at one end thereof and a connecting portion 3 at the other end thereof. The joint further comprises a ball and rod member 4 having at one end thereof a ball 5 which has high sphericity and which is rotatably and movably secured with a minimum necessary clearance within the ball receiving portion 2 of the aforesaid holder 1. The ball and rod member 4 comprises a connecting rod 6 at the other end thereof. The ball joint further comprises a sealing member 7 which is located between the aforesaid ball receiving portion 2 and a base portion of the connecting rod 6 of the ball and rod member 4. The sealing member 7 serves to accommodate lubricant such as grease which is supplied between the ball 5 and the ball receiving portion 2. The sealing member 7 also serves to prevent entrance of dust and so forth into the region between the ball 5 and the ball receiving portion 2. The holder 1 is formed in such a manner that the ball receiving portion 2 has an opening arranged substantially at a right angle with respect to the connecting portion 3 thereof. An oil basin or reservoir portion 9, which is closely sealed by a cover material 8, is formed at the bottom portion of the ball receiving portion 2 of the holder 1.

The cover material 8 which forms the aforesaid oil reservoir 9 employed in this embodiment is "i -1 -4 9 - composed of a thin disc plate. It is fixed by caulking an annular projection 10 which is provided around the circumference of an opening which serves as the oil reservoir 9 by casing the holder 1, the opening being formed at the bottom portion of the ball receiving portion 2. The connecting portion 3 of the holder 1 is formed having an internal thread 3a. The connecting portion 6 of the ball and rod member 4 is formed having an external thread 6a. A hexagonal tool securing portion 11 is formed in the base portion of the ball and rod member 4 and is secured by a tool for rotating the ball and rod member 4 at the time of securing the outer threads 6a to the other member. A tool securing portion 12 of a substantially rectangular shape to which a tool is secured is also formed at one end of the connecting portion 3 of the holder 1. Furthermore, one end portion 7a of the aforesaid sealing member 7 is secured to the aforementioned tool securing portion 11. The other end 7b is secured to the edge of the opening of the ball receiving portion 2, a lubricant space 13 thus being formed therebetween. An edge surface 14 is formed in the edge portion of the opening of the ball receiving portion 2 of the aforesaid holder 1 for the purpose of regulating the angle through which the ball and rod member 4 may move. A method of manufacturing the ball joint described above will now be described. 30 As is shown in Figure 4, a ball 4a having high sphericity is set as a core for the spherical ball receiving portion 2 in a holder casting die 20 which is vertically divided. The ball 4a, which is used as a core, is inserted between an upper die member 21 and a supporting portion 23 which is provided on a lower die member 22, the diameter of which is larger than that of the lower portion of the main body 4b of the rod that is to form a connecting portion 6 of the ball and rod member 4 for the purpose of fixing. A core 24 for forming the inner threads 3a is set at the portion which forms the connecting portion 3 of the holder 1.

Then, a die-cast fusible alloy is cast into the holder casting die 20 so as to cast the holder 1. In the cast holder 1, as shown in Figures 5 to 7, the ball 4a, which will form the ball 5 of the ball and rod member 4, is cast and held in the ball receiving portion 2 of the holder 1. An opening 9a which becomes an oil reservoir 9 is formed in the bottom portion of the ball receiving portion 2. An annular projection 10, which is caulked at the time of fixing the cover material 8, is formed in the circumference of the edge of the opening. In this embodiment, the inner threads 3a and the tool securing portion 12 are formed, in this state, in the connecting portion 3 of the holder 1. After casting the holder 1 with the ball 4a, as shown in figure 8, a supporting electrode 25 for projection welding is inserted through the opening ga which is formed by the supporting portion 23 of the lower die member 22 in the bottom portion of the holder 1 at the time of casting the holder 1 so as to support the ball 4a. The ball 4a and the main body 4b of the rod are abutted against each other at their ends. Under a predetermined pressure P a predetermined electric current is passed for a predetermined weld time for the purpose of projection welding these ends. The electric current is passed again in this state for the purpose of tempering. A holder 1, with a ball 5 of the ball and rod member 4 cast in the spherical ball receiving portion 2, is thus formed.

The supporting electrode 25 has a diameter d2 of its supporting portion 25a that is larger than the diameter dl of the aforesaid main body 4d of the rod, and smaller than the diameter d3 1 of the opening 9a, as a result of which, it is not in contact with the circumferential surface of the opening 9a (that is, the relationship is dl<d2<d3) and this can be helpful for efficient projection welding between the ball 4a and the main body 4b of the rod. Furthermorey the ball 4a and the main body 4b of the rod can be welded without any deterioration in smoothness and sphericity of the ball 4a to which the supporting electrode 25 is in contact. In order to ensure that the ball 5 of the ball and rod member 4 can rotate and move with respect to the spherical ball receiving portion 2 of the holder 1, a small space is formed between the ball receiving portion 3 of the holder 1 which has been thus formed and the ball 5 of the ball and rod member 4 by applying an external force by, for example, applying a small impact by patting the outer circumference of the ball receiving portion 2, or applying a tension to the ball and rod member 4. Then the opening 9a which is formed at the bottom portion of the receiving portion 2 of the holder 1 is filled with the lubricant such as grease and so forth. The cover member 8 is then fitted into the edge of this opening ga and the annular projection 10 which is formed in the circumference of this opening 9a is caulked so as to form the oil reservoir 9 with this cover member 8 fixed to the edge of the opening 9a.

Furthermore, as shown in Figure 1, the sealing member 7 is secured to the portion between the edge of the opening in the ball receiving portion 2 of the holder.1 and the tool securing portion 11 which is formed at base portion of the connecting portion 6 of the ball and rod member 4, the-lubricant pocket 13 which is formed by this sealing member 7 being filled with the lubricant such as grease and so forth.

- 12

Claims

CLAIMS:

1. A method of forming a ball joint comprising, placing a ball in a holder die defined by two die members, said ball being supported by a supporting portion of one of said die members, casting the holder by pouring a metal into said die whereby a receiving portion of said holder is defined about said ball and said receiving portion has an opening formed by said supporting portion, and removing the cast holder and ball from said die.

2. A method according to claim 1 further comprising inserting a supporting electrode through said opening so as to support said ball, projection welding a connecting portion to said ball to form a ball member, applying an external force to said ball and said receiving portion to form a clearance therebetween, and closing said opening to form an oil reservoir.

3. A method according to claim 2 comprising fixing in place a cover member by caulking the rim of said opening to form said oil reservoir.

4. A method according to claim 1,2 or 3 wherein said ball supporting portion has a diameter substantially the same as or greater than the diameter of said connecting portion.

5. A ball joint comprising, a holder having a ball receiving portion at one end thereof and a connecting portion at the other end, and a ball member having a ball at one end thereof and a connecting portion at the other end, said ball being rotatably held in said ball receiving portion, wherein said ball receiving portion is provided with an opening _k 0, 13 at a position remote from the connecting portion of said ball member and said opening is closed by means of a cover member so as to define an oil reservoir.

6. A ball joint according to claim 5, wherein the diameter of said opening is substantially the same as or larger than the diameter of the connecting portion of said ball member.

7. A ball joint according to claim 1 or 2, wherein said ball and said connecting portion of said ball member are joined together by projection welding.

8. A ball joint according to claim 1, 2 or 3 wherein said cover member is fixed in place by caulking the rim of said opening.

9. A ball joint according to any of claims 5 to 8 wherein said connecting portions comprise rod members bearing threaded portions.

10. A ball joint according to any of claims 5 to 9 comprising a sealing member disposed between said holder and said ball member.

11. A ball joint substantially as hereinbefore described with reference to the acompanying drawings.

12. A method of forming a ball joint substantially as hereinbefore described with reference to the accompanying drawings.

Published 1988 at The Patent Office. State House, 66 71 High Holborn, London W01 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mwy Cray. Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray. Kent. Con 1187.