PL241396B1 - Adjustable ball and socket joint - Google Patents

Abstract

The subject of the invention is an adjustable ball joint, including at least two joint units - a first joint unit including a pin (1) terminating in a spherical cup (10) having two side cuts dividing it into two parts forming an elastic fork and a second joint unit including a ball pin (2) having an intersection forming two hemispherical parts (3) connected to each other by the lower part of a ball pin (2). The essence of the invention is the use in the adjustable ball joint of a flexible spherical cap (10) with an adjustable pressure, which allows you to adjust its mobility, resistance to movement and play in the connection of spherical surfaces, ensuring the joint rotation in any direction. The resilient spherical ball (10) also enables automatic adjustment of the resistance to motion depending on the load force of the adjustable ball joint. Moreover, the proposed ball joint can be connected and disassembled without disassembly and reassembly.

Description

The subject of the invention is an adjustable ball joint for use in technical systems where high stability of movement and position as well as low resistance to movement are required, e.g. in kinematic nodes of robots, especially multi-legged walking robots, exoskeletons and humanoid robots. It can also be used in manipulators, industrial robots, measuring devices and micromechanisms.

In the prior art, for example from the patent specification PL 211105, a ball joint is known which has a spherical part, a fixed part and a protective-sealing unit, which is a cap-shaped cover with a two-stage seat, with embedded sealing elements adjacent to the surface of the spherical part of the joint.

Document EP 0481212 shows a ball joint having a spherical head, a joint pin and a ball connecting pin housed in a coupling holder with a vessel-shaped interior in which it can be pivoted. The ball joint is slideably mounted in a bearing connected to the coupling housing.

Another ball joint disclosed in PL 198014 consists of two parts, the second part of which has a spherical bore snap-fitted to a first spherical-shaped part with a protruding neck having a hemispherical skirt sliding on the outer surface of the spherical opening, the diameter of the spherical opening being smaller. from the diameter of the sphere. In addition, the ball with the outgoing neck is made of a single material.

The joint described in US 8714882 has a disc spring in an annular recess in an axially loaded lower plain bearing. The disc spring is used to preload and compress the upper bearing down towards the spherical end of the head. Preloading prevents the ball pin from rotating - axially or rotating - until a minimum load is applied to exceed the preload and cause movement.

US 9291195 shows a ball joint assembly in which the pin ball portion is housed within a cup-shaped bearing bushing and the shaft portion of the ball portion protrudes from the open interior through the open end of the housing to engage with another component. The lower bearing is housed within the bearing bushing and includes an extension that extends into the bore of the bearing bushing holding the lower bearing in a predetermined position within the bearing bush.

The universal ball joint disclosed in US publication 8353776 comprises a first rotary body and a second rotary body that are pivotally connected to each other. The first rotary body has an elliptical head and a connecting portion. The head has a major axis and a minor axis perpendicular to the major axis. The second rotating body defines an elliptical ball seat rotatably engaged with the head of the first rotating body such that the head can rotate about a major axis or minor axis of the head.

A ball joint according to U.S. Patent 6,533,491 is characterized in that the lower bearing defines a lower bearing surface surrounding the spherical head on the side of the housing bore, and an opposite, movable upper bearing defines the upper bearing surface, the upper bearing being pressed against the spherical head by a spring, so to allow movement towards the lower bearing in the event that the spherical head or lower bearing is wearing out.

US 7083356 discloses a ball joint with an angular restraint system which allows free rotation of the ball pin and at the same time restricts its angular movement in a predetermined direction. A motion restraint system according to a preferred embodiment is used in steering or linkage rods where rotational movement about its longitudinal axis is undesirable.

Publication EP 1662158 shows another ball joint having a seat with a housing housing the ball-shaped joint portion and allowing it to slide. The holder of the housing is shaped to prevent the holder and the seat from moving towards one another. The hinge comprises a frustoconical member in the holder and a congruent part of the cone in the seat. Further, the holder and the socket have grooved surfaces engaging each other for: securing the housing to the socket; preventing relative movement between the housing and the seat, and sealing the first peripheral contact surface between the housing and the seat.

There is also prior art an embodiment of a ball joint air spring disclosed in EP 1797346. This solution comprises a ball joint which has a spheroidal bearing element in the bearing shell. It is possible to position the bearing shell on the spheroidal bearing element by means of a clamping element.

PL 241 396 B1

Another ball joint presented in the patent description P.419462 is characterized by the fact that it consists of a plastic bushing and a metal ball pin, mounted in the socket of the joint of the metal body. To the bottom of the bushing, through a metal washer, there is an elastic pressure ring, compressed by the plug closing the joint seat, which, as a result of compression, constantly presses against the bushing, eliminating play in the joint.

EP 0075414 A1 discloses a ball joint in which the head of the ball pin is mounted in a bearing ring, in a seat. The bearing sleeve is surrounded by a compressed elastomeric sleeve which encloses the bearing ring at the equatorial region of the head to press the ring against the head to apply a torque load. The torque load can be varied by changing the hardness of the elastomeric material of the sleeve.

In a ball joint according to US Patent No. 3,951,557, a split plastic bearing is brought into contact with the ball by the action of a spring which is held in the bore by the cover plate.

US 6,010,271 shows a ball joint having only one hole through which all components are installed during assembly and through which the pin protrudes. These items include: compression spring, polymer bottom bearing, spindle, and metal top bearing.

Another ball joint disclosed in EP 1866552 uses a split upper bearing shaped to provide a bearing surface for the top and side of the ball pin and to engage the housing and ball pin simultaneously.

In the solutions existing in the state of the art, there is a problem of regulating the mobility, resistance to movement and play in the connection of spherical surfaces. The object of the present invention is to propose an adjustable ball joint that provides a solution to this problem, allowing rotation in any direction and self-regulation of the resistance to motion depending on the load on the joint. Another object of the invention is to provide a ball joint that can be connected and disassembled without disassembly and reassembly.

The adjustable ball joint according to the invention consists of two units. The first pivot assembly includes a pin terminated in a dish with a spherical inner surface which has two side cutouts dividing it into two parts forming a resilient fork. A thread is made on the outer surface of the pin, on which a pressure nut is mounted, which with its conical inner surface exerts a pressure on the outer conical surface of the spherical ball. As a result of this solution, the rotational movements of the nut are converted into angular deflections of elastic forks ending with hemispheres. The second joint assembly has a ball pin with a blind hole terminating in a conical inner surface. The mandrel has an intersection forming two hemispheres connected to each other through the lower part of the mandrel. In addition, the spindle has two side cutouts that define openings of a substantially rectangular shape. The notches in the spindle are parallel to its intersection. This configuration of the upper part of the ball pin forms two elastic arms. Moreover, the ball pin has an external thread in its lower part, on which a bush with a blind hole is mounted, the axial position of which is locked with a locknut. In turn, in the coaxial holes of the mandrel and the sleeve of the same diameter, there is a sliding pusher ending with a cone, pressed against the conical inner surface in the upper part of the cut ball pin by a pressure sleeve with external thread, located in the hole in the lower part of the sleeve.

The pressing force of the mating surfaces of the joint is pre-adjusted by screwing the pressure sleeve with external thread into the threaded hole of the sleeve. The face of the pressure sleeve rests on the shoulder of the pusher. Thanks to this solution, the axial movement of the pusher is converted into the angular deflection of the elastic, hemispherical parts of the ball pin.

Preferably, a nut is mounted in the lower part of the pusher, the upper face of which presses the cup spring against the lower face of the pressure bushing. After the vertical force on the pusher ceases, the cup spring exerts a spring pressure on the nut causing the pusher to return to its limit position. This displacement of the follower causes the elastic, hemispherical portions of the ball pin to be clamped. As a result, the resistance to movement of the joint increases, and in extreme cases, it may become blocked.

The use of an elastic spherical canopy with adjustable pressure in the adjustable ball joint enables the adjustment of its mobility, resistance to movement and play in the connection of spherical surfaces, ensuring the joint rotation in any direction. The resilient spherical ball also makes it possible

Automatic adjustment of the resistance to motion depending on the load force of the adjustable ball joint. The advantage of the invention is therefore its adaptability to the changing operating conditions of the adjustable ball joint. An additional advantage of the adjustable ball joint is the possibility of connecting and disconnecting it, without the need to disassemble and reassemble, thanks to the elastic deformation of the mating surfaces, which constitute specific fragments of spherical cups, which are limited by the selection of the height of the spherical ball.

The subject of the invention can be used in various kinematic units and nodes, both in exoskeletons, microrobots, humanoid robots and industrial robots, as well as in working machines. Depending on the application, the dimensions and materials of the joint components should be selected. Preferably, the pin and the ball pin are made of materials with very good elastic properties, i.e. high elasticity point, high elasticity / yield point ratio, high tensile strength. Additionally, in industrial robot applications, good fatigue strength and high resistance to corrosion and abrasive wear are desirable. For example, the pin and the ball pin can be made of 50S2 silicon steel, 65G manganese steel, 50HS chrome-silicon steel, 51 CrV4 (1.8159) chrome-vanadium alloy, X 10CrNi88 (1.4310) X22 CrMoV 121 (1.4923), titanium alloys, e.g. Ti6A14V-PE-UHMW. These elements can also be made by sintering metal powders, for example titanium or magnesium, as well as by additive manufacturing. The remaining elements of the joint can be made of typical construction materials, such as: structural steels and their alloys, as well as of plastics with good mechanical properties, for example: polyamide, PBT, polycarbonate or polyester.

The subject of the invention is described in more detail below in an embodiment of the invention shown in the drawing, in which they show: Fig. 1 a ball joint in a front view, Fig. 2 a ball joint in a half view and a half section, Fig. 3 detail A of Fig. 2, the bearing surface of the follower cone fig. 4 fig. 5 fig. 6 with the conical inner surface of the ball pin, detail B from fig. 2, illustrating the screw connection of the pressure sleeve with the sleeve in which the pusher is slidably seated, the forged joint in isometric view, the pusher, fig. 7, 8 and 9 ball pin in front view, half side view and half section side view and isometric view, respectively. and in isometric view, fig. 13, fig. 14, fig. 15, fig. 16, clamp nut in half view and half section, bush in half view and half section, pressure bush with external thread in half section. view and half-section, view of the joint in the position of the limit deflection of the pin with the spherical ball.

In the embodiment of the invention shown in FIGS. 1 to 5, the adjustable ball joint comprises two units. The first adjustable ball joint assembly comprises a pin 1 (Figures 7 to 9) terminating in a spherical bowl 10 with a spherical inner surface 9. Spherical cap 10 has two side cuts dividing it into two parts forming a fork with width b. On the outer surface of the pin 1 an external thread 11 is provided on which a pressure nut 12 is mounted (Fig. 13) having a conical inner surface 13 through which it exerts a pressure on the conical outer surface 14 of the spherical cap 10 of the pin 1.

The second adjustable ball joint assembly has a ball pin 2 (Figures 10-12) with a cylindrical blind hole 15 ending in a conical inner surface 16. Ball pin 2 has an intersection 5 forming two hemispherical parts 3 connected to each other by the lower part of the ball pin 2. Furthermore the ball pin 2 has two side cutouts, forming openings 19 of substantially rectangular shape, the cutouts parallel to the cut 5. In the lower part of the ball pin 2, an external thread 21 is provided, on which a bushing 4 (Fig. 14) with a through hole is mounted. cylindrical bore 20. The axial position of the sleeve 4 is blocked by a locknut 18. In the concentric cylindrical bores 15 and 20 respectively - the ball pin 2 and the sleeve 4 - by one

The pusher 6 (Fig. 6) is slidably mounted, ending with a cone 7. The conical 1 of the pusher 6 is pressed against the conical inner surface 16 in the cut upper part of the ball pin 2.

The pressing force of the mating surfaces of the outer parts of the hemispherical parts 3 of the ball pin 2 and the spherical inner surface 9 of the spherical cup 10 of the pin 1 of the adjustable ball joint is pre-adjusted by screwing the pressure sleeve 8 with an external thread into the threaded cylindrical bore 20 of the sleeve 4. The front surface of the pressure sleeve 8 rests on the protrusion of the pusher 6. Thanks to this solution, the axial movement of the pusher is converted into the angular displacement of the elastic hemispherical parts 3 of the ball pin 2.

In the lower part of the pusher 6 there is a nut 17, the upper face of which presses the diaphragm spring 22 against the lower face of the pressure sleeve 8. After the vertical force F exerts on the pusher 6, the diaphragm spring 22 exerts a spring pressure on the nut 17, causing the pusher to return. 6 to its limit position. The return movement of the pusher 6 causes the elastic, hemispherical 3 parts of the ball pin 2 to be clamped, as a result of which the resistance to movement of the joint increases, and in extreme cases it becomes blocked.

The spherical ball 10 of the joint pin has a width b and a height H smaller than the diameter d of the internal spherical surface 9 of the spherical cap 10 of the pin 1, preferably: H / d = 0.6-0.8, b / d = 0.5-0, 6 and (H + b) / d <1.3. In the embodiment shown in Figs. 1 and 2, the spherical ball 10 has a width b = 40 mm and a height H = 38 mm, which are smaller than the diameter d = 60 mm, and the ratio values are: H / d = 0.63 and b / d = 0.67 and (H + b) / d = 1.3.

The elastic deformations of the two-armed spherical cap 10 are limited by the position of the conical outer surface 14 of the spherical bowl 10, and thanks to the intersection 5 and the axial displacement of the cone 7, the position of both parts of the spherical inner surface 9 can be changed. In the plane perpendicular to the pusher axis 6, the adjustable ball joint can rotate in the range from 0 ° to 360 °, and in the plane coinciding with the pusher axis 6, the articulation angle α is limited and in the case of the embodiment of the invention described above (Fig. 16) within ± 30 ° in relation to the pusher axis 6.

In an embodiment of the articulation in exoskeleton applications, when the load with a vertical force does not exceed 600 N, the pin 1 and the ball pin 2 are made of Ti6A14U-PE-UHMW titanium alloy, and the remaining elements are made of aluminum alloys, e.g. AlSi5Cu2.

In other embodiments, the pin 1 and the ball pin 2 are made of high-strength, carbon-fiber reinforced plastics, e.g. PA 66 CF20.

List of markings:

- pin

- ball pin

- hemispherical part

- sleeve

- the intersection of the sphere

- pusher

- cone

- pressure sleeve

- the spherical inner surface of the spherical cap

- spherical ball

- external thread

- clamping nut

- conical inner surface of the pressure nut

- conical outer surface of the spherical cap

- cylindrical bore of the ball pin

- conical inner surface of the ball pin

- nut

- lock nut

- hole

- cylindrical bore of the sleeve

- external thread of the ball pin

- disc spring

PL 241 396 B1

F- the force loading the joint

H - height of the spherical ball b - width of the spherical ball d - diameter of the spherical inner surface of the spherical ball α - angle of the joint deflection

Claims (5)

1.Adjustable ball joint including at least two joint units - a first joint unit comprising a pin terminating in a spherical cup with a spherical inner surface and a second joint unit having a ball pin, characterized in that the spherical ball of the pin 1 has two side cutouts dividing it into two parts forming an elastic fork and on the outer surface of the pin 1 there is a thread 11, on which a pressure nut 12 is mounted, having a conical inner surface 13, which is pressed against the outer conical surface 14 of the spherical ball 10, and the ball pin 2 has a blind hole 15 ended with a conical surface inside 16 and has an intersection 5 forming two semicircular portions 3 connected to each other by a lower portion of a ball pin 2, in which, in addition, two lateral slots are made to form openings 19 of substantially rectangular shape, the slots being parallel to the intersection 5, moreover ball pin The new 2 has an external thread 21 in its lower part, on which a bushing 4 with a through hole 20 is mounted, the axial position of which is locked by a locknut 18, and a pusher 6 ending with a cone 7 is slidably placed in the coaxial holes 15 and 20 of the same diameter, which presses to the conical inner surface 16 in the upper part of the cut ball pin 2 through the pressure sleeve 8 with external thread, located in the bore of the lower part of the sleeve 4. 2. Adjustable ball joint according to claim 1, characterized in that a nut 17 is mounted in the lower part of the pusher 6, the upper face of which presses the diaphragm spring 22 against the lower face of the pressure bush 8. Adjustable ball joint according to claim 1, characterized in that the spherical ball 10 of the pin 1 has a width b and a height H which are smaller than the diameter d of the inner spherical surface 9 of the spherical ball 10, preferably: H / d = 0.6 + 0.8, b / d = 0.5 + 0.6 and (H + b) / d <1.3. 4. Adjustable ball joint according to claim 1, characterized in that the ball joint in the plane perpendicular to the pusher axis 6 is adjustable in the range from 0 ° to 360 °, and in the plane coinciding with the pusher axis 6, the angle α of the adjustable ball joint with respect to the pusher axis 6 is limited and is within ± 30 °. 5. Adjustable ball joint according to claim 1, characterized in that the pin 1 and the ball pin 2 are made of materials with very good elastic properties, i.e. high yield strength, high yield strength to yield strength, high tensile strength and good tensile strength. resistance to fatigue and high resistance to corrosion and abrasive wear.