WO1991005960A1

WO1991005960A1 - A ball joint fixture

Info

Publication number: WO1991005960A1
Application number: PCT/SE1990/000671
Authority: WO
Inventors: Rolf Andersson
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-10-20
Filing date: 1990-10-18
Publication date: 1991-05-02
Anticipated expiration: 1992-04-20
Also published as: SE8903466D0; AU6619390A; SE464661B

Abstract

The invention concerns a ball joint fixture of the kind comprising a ball head (1) and a friction element (9) arranged, when actuated by a pressurized medium, to exert pressure on the ball head. The ball head mounting means consists of two annular seat members (2, 3) which from opposite directions are pressed against one another and against the ball head. The seat member faces positioned opposite the ball constitute annular seating faces in abutment against said ball head. An attachment member projects through the central aperture of one of said annular seat members in order to support the object to be secured by means of the fixture while the friction element extends through the central aperture of the opposite annular seat member.

Description

A BALL JOINT FIXTURE

The present invention concerns a ball joint fixture of the kind comprising a ball head and a friction element arranged, when actuated by a pressurized medium, to exert pressure on the ball head- Ball joint fixtures of the kind mentioned above are al eady known, for instance from the US Patent Specification No.4374497, disclosing a table which is supported by a central pillar and a number of legs positioned at a distance from the pillar and fitted at both ends with fixtures of the kind outlined above. The prior-art fixtures are used solely as a supplementary securing means, the individual legs also being arranged to be fastened in the desired position of extension.

The main purpose of the subject invention is to provide a ball joint fixture of the kind indicated which is simple in construction, which offers a high degree of safety also when used to alone carry an object, and which is easy to operate while at the same time it has a long useful life, also when operating in polluted atmospheres.

These purposes are achieved in accordance with the invention by means of a ball joint fixture which is essentially characterized in that the means for mounting the ball head consists of two annular seat members which are arranged to be forced, from two opposite directions, against each other and against the ball head, and the faces of which positioned opposite the ball head constitute annular seating faces in abutment against said ball head, and in that an attachment member - projects through the central aperture of one of said annular seat members in order to support the object to be secured by said fixture while the friction element extends through the central aperture in the opposite annular seat member. One embodiment of the inventive object will be described in closer detail in the following with reference to the accompanying drawings, wherein:

FIG. 1 is an axial cross-sectional view through a ball joint fixture designed in accordance with the invention, and FIG. 2 illustrates schematically the pressurized medium supply system used to secure the ball joint fixture in position.

The ball joint fixture illustrated in the drawing comprises a ball joint 1 which is supported between two annular seat members 2 and 3 which are arranged to be urged from two opposite directions against one another and against the ball head. Tightening bolts 4 keep the annular seat members pressed towards each other. In addition to passing through the annular seat members 2 and 3 the tightening bolts 4 also pass through a base 5 having a centrally located cavity 6 of cylindrical configuration. A piston 7 is inserted in the cavity 6 for vertical movement therein and is fitted with a sealing ring 8 whereby it maintains a sealed sliding fit against the inner circumferential faces of the cavity 6. A friction body 9 is positioned centrally on the upper face of the piston and in accordance with the embodiment illustrated the upper face of the friction body 9 has a curvature matching that of the ball head.

When upon tightening of the bolts 4 the two annular seat members 2 and 3 are pressed against one another and against the base 5 a closed cavity is formed underneath the ball head, in which is housed the movable piston 7. This closed cavity protects the piston 7 and its path of movement as well as the friction body 9 from external pollution, which efficiently attributes to the long serviceble life of the device.

The lower annular seat member 3 as well as the upper annular seat member 2 are formed with comparatively large central apertures- since they need not overlie the ball head 1 over any major proportion of the peripheral ball head surface. Owing to this arrangement a comparatively large space is formed in which to accommodate the friction body 9 inside the lower annular seat member but in addition thereto considerable space is created for free movement of the pin 10 which is mounted on top of the ball head, said pin intended to support, on its upper section 10a which in accordance with the embodiment illustrated in the drawing is formed with screw threads, a table, a screw vice or any other suitable mechanism designed to secure the object to be supported by the ball joint fixture. In accordance with the embodiment illustrated in the drawing the fixture is attached to a supporting base 11 of some kind, which m be attached to a floor stand or similar means. The supporting base 11 may be adjustable vertically, for instance by means of a lifting devi operated in any suitable manner, such as by means of hydraulic, pneumatic, electronic or mechanical means. Numeral reference 12 designates the pressurized medium supply channel which from the exterior opens into the cylindrical cavity 6.

By increasing the pressure of the pressurized medium inside th cavity 6 the frictional body 9 is urged into abutment against the ball head, locking the latter in position.

In the circuit diagram illustrated in Fig. 2, reference numeral 13 designates a source of pressurized medium supplying the ball joint fixture with pressurized medium, preferably compressed air. Referenc numeral 14 designates a pressure regulator, and by 15 is designated a coupling means including a non-return valve 16. Numeral reference 17 designates a reversible through-flow valve and numeral 18 designates the mounting arrangement of the ball joint generally, including the locking piston, only partly shown on the drawings. The pressure regulator 14 has an inlet port 19, an outlet port 20 and its through-flow direction is indicated by arrow 21. The branch coupling 1 has an inlet 22, an inlet port 23 and an outlet port 24 and the non-return valve 16 is positioned in the path of communication between the inlet port 23 and the outlet port 24 in such a manner as to ensure that fluid entering through the inlet port 23 is directed in the direction indicated by arrow 25. The reversible valve 17 has an inlet port 26, an outlet port 27 and an outlet port 28. The source of pressurized medium 13 is in direct communication with the inlet port 1 of the pressure regulator 14 and with the inlet port 26 of the valve 17. Also, the outlet port 20 of the pressure regulator 14 communicates with the inlet port 22 of the coupling member 15. The outlet port 27 of the valve 17 communicates with the inlet port 23 of the coupling means 15, and the outlet port 24 of the coupl ng means 15 communicates with the inlet channel 12 leading to the cylindrical cavity 6. The mode of operation of the device will be described in the fol1owing.

When the valve 17 assumes position A pressurized medium flows via the conduit 29, the ports 26, 27 of the valve 17, the conduit 30, the inlet port 23 of the coupling means, the non-return valve 16, the conduit 31 and through the inlet channel 12 into the cylindrical cavity 6. In this position, a high pressure acts on the piston 7 and consequently, by way of the friction body 9, on the ball head 1, whereby the latter is maintained securely in a stable and fixed position.

When the valve 17 assumes position B the communication via conduit 29 is interrupted, and the non-return valve 16 prevents flow of pressurized medium in the direction towards the valve 17. On the other hand, pressurized medium is supplied to the cylindrical cavity 6 by way of the reducing valve 14, the conduit 32, the branch coupling 15, the conduit 31 and the channel 12. In this manner a remaining minimum pressure thus still is applied on the piston 7 and consequently on the friction body, which retains the ball head in position. This pressure preferably may be shifted by means of the pressure regulator 14 in such a manner that the work piece, table or equivalent means supported by the ball head may be reset into the desired rotational or tilting position without falling off. When the work piece is heavy, the minimum pressure could be increased accordingly and be decreased, should the work piece be light-weight. Preferably, the valve 17 is set to normally assume position A but to assume position B when actuated, in order again to resume position A upon cease of actuation. Actuation of valve 17 suitably is effected by means of a spring-back pedal-operated or manually operated regulating means.

Even if the pressure on piston 7 were to cease entirely, the secure mounting of the ball head 1 still would be ensured in that the annular seat members 2 and 3 will support the ball head 1 independently of the force of abutment of the friction body 9 against the ball head. Preferably, the two annular seat members 2 and 3 are arranged to be adjusted in a direction towards and away from each other for adjustment of the seat retaining pressure acting on the ball head, for instance to compensate for wear.

The invention is not limited to the embodiment which has just been described in the aforegoing for illustrative purposes only but may be varied as to its details within the scope of the appending claims without departure from the basic inventive idea. For instance, within the scope of the claims it is possible to mount the friction body on a separate force-exerting means which need not necessarily form a closed unit together with the annular seat members, although the preferred embodiment provides a more enclosed and protected construction. In accordance with the embodiment illustrated and described, the piston 7 has a diameter which even surpasses the diameter of the ball head 1, resulting in a locking force which is considerable, also when the pressure inside the cavity 6 is low. However, it obviously still is within the scope of protection of the invention to use a smaller-diameter piston. In accordance with the embodiment illustrated the lower annular seat member 3 forms the face against which the piston 7 abuts when the frictional body 9 is worn out, but this end-position abutment face obviously could be provided in some other suitable way. The ball joint fixture referred to obviously could be used to support any suitable object or article which need not necessarily be a working table or a work piece.

Claims

1. A ball joint fixture of the kind comprising a ball head and a friction element arranged, when actuated by a pressurized medium, to exert pressure on the ball head, c h a r a c t e r i z e d in that the means for mounting the ball head consists of two annular seat members (2, 3) which are arranged to be pressed from opposite directions against each other and against the ball head, and the faces of which opposite the ball head constitute annular seating faces in abutment against said ball head, and in that an attachment member (10) projects through the central aperture of one of said annular seat members in order to support the object to be secured by means of the fixture, while the friction element (9) extends through the central aperture of the opposite annular seat member (3).

2. A ball joint fixture as claimed in claim 1, c h a r a c¬ t e r z e d in that the friction element (9) is positioned on a piston (7) which is operated by a pressurized medium and which is movable inside a cylinder (6), said cylinder forming the bottom of a housing which together with the annular seat members (2, 3) enclose the ball head over more than 180°.

3. A ball joint fixture as claimed in claim 1 or 2, c h a r- a c t e r i z e d in that the annular seat members (2, 3) are pressed mechanically together into abutment against the ball head independently of the abutment of the friction element (9) against the ball head (1).

4. A ball joint fixture as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the power cylinder (6, 7) acting of the friction element (9) is connected to a source (13) of pressurized medium by way of a pressure control system by means of which the pressure affecting said friction element may be varied between a maximum pressure to lock the ball head in position and a minimum pressure (holding pressure) which is set to ensure that the ball head is retained in the desired position of adjustment, said position being, however, variable by application of an external force on said object supported by the fixture.

5. A ball joint fixture as claimed in claim ^ c h a r a c¬ t e r i z e d in that the pressure system Comprises two communication channels (21), one containing a pressure-reducing regulator (14) and one containing a reversible valve (17) for connecting and disconnecting the communication channel having the higher pressure.

6. A ball joint fixture as claimed in claim 5, c h a r a c- t e r i z e d in that the pressurized medium is compressed air.

7. A ball joint fixture as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that the annular seat members

(2, 3) are arranged to be applied against the ball (1) with a pressure adjustable in dependence of the surface wear on said ball head (1).

8. A ball joint fixture as claimed in any one of the preceding claims, c h a r a c t e r i z e d in that it is designed to be mounted on a vertically displaceable stand.

9. A ball joint fixture as claimed in claim 8, c h a r a c- t e r i z e d in that the vertically displaceable stand is equipped with a vertical jack the piston rod of which supports said ball joint fixture.