DEBEADING APPARATUS

Technical Field of the Invention

The invention relates to a pressing apparatus for tyre changing machines, particularly suitable for pressing the sides of tyres during the removal phases from rims. Background Art

As is known, tyre changing machines have tools designed to assist and help operators during operations to be performed on wheel tyres, such as, e.g., the fitting and removal of tyres. These tools comprise a pressing member that is designed to press on the sides of the wheel tyres that are arranged and fastened on a work platform with which the tyre changing machines are equipped.

This member comprises an arm of varying length and movable, which extends substantially in a direction parallel to the platform supporting surface, normally horizontal, from a turret of a tyre changing machine turned upwards and which is fitted so it can move closer to or away from the platform.

At the free end turned towards this, the arm bears a disc that is free to turn around a rotation axis substantially transversal with respect to the arm, in such a way as to have an outer edge that protrudes beyond the arm and which is intended to be placed in contact with the sides of the tyres of the wheels fastened on the work platform when one side of a tyre has to be pressed.

When a tyre has to be removed from the rim of a wheel, it is first of all deflated and then, the operator moves the arm towards the platform and adjusts its length and horizontal position, so that the peripheral edge of the disc is aligned, and comes into contact, with an area of one side of the tyre, known as bead, i.e. with a reinforced side band and defined at the internal hollow edge of the tyre.

When the disc is positioned resting on this bead, the operator further operates the devices that make the arm move, moving it further in the direction of the work platform, pressing the bead with the edge of the disc. This pressure causes the detachment of the bead from the edge of the rim against which the bead is normally resting during rolling on the road and this bead, in deforming, moves towards the inner channel of the rim which has, as is known, a

smaller diameter than the outermost diameter on which the inner hollow edge of the tyre is normally fitted.

To completely push the whole side of a tyre towards the inner channel of the rim, the operator causes the platform to turn while the disc presses at the same time on the bead and turns on this without there being any appreciable rubbing between these: the rotation of the platform together with the pressure of the disc causes the gradual detachment of the tyre bead from the edge of the rim along the entire circumference of this. When the tyre bead is completely detached from the edge of the rim and is completely moved towards the central channel of this, the tyre is loose with respect to the rim and the operator, by means of adequate manual operations or with the aid of a lever, removes the side of the tyre over the edge of the rim and takes it off the rim. By pressing on the opposite side, the tyre can be fully removed from its rim. By operating in the reverse sequence, the operator can fit a tyre on a rim, pressing on the beads with the disc, so these move over the edges of the rim and position in its central channel.

A subsequent quick inflation causes the substantially instantaneous dilation of the tyre and the automatic adjustment of the beads which adhere to the respective rim edges.

OBJECTS OF THE INVENTION This state of the art has a drawback which is the risk of damaging the edges of the rim during the pressure applied by the disc on the tyre beads.

In fact, in the presence of particularly rigid sides, e.g., when the tyres are of the so- called lowered type used by high-performance vehicles, the force required to push the beads towards the central channel is very high. In this case, the movement of the pressing disc is imprecise due to the resistance of the beads to bending and the peripheral edge of this can slip and accidentally come into contact with the edges of the rim, damaging these.

To this must be added the fact that usually these lowered type of tyres are fitted on special rims that are very costly and delicate, being made with alloys of materials lighter than the iron or steel normally used to make conventional rims.

Consequently, damage to these rims is to be avoided so as not to create problems of

mechanical duration and aesthetics, the latter being normally much refined. One object of the invention is to improve the state of the art.

Another object of the invention is to make a pressing apparatus that allows pressing on the sides of tyres of any type, without risking damage to the rims on which they are fitted.

Another object of the invention is to make a pressing apparatus that allows selecting the operation of a pressing part, in such a way as to adapt it to the rigidity of the sides of a tyre to be pressed. According to one aspect of the invention, a pressing apparatus is provided suitable for pressing the sides of tyres, comprising: a supporting element; a pressing disc freely mounted rotating on an arm which can be fitted to said supporting element, characterized by the fact that said arm is fitted to said supporting element in a way that can be chosen between a fixed configuration and an oscillating configuration. According to another aspect of the invention, a removal method is provided for removing tyres from rims of wheels having inner channels defined between parallel edges, comprising pressing on the sides of said tyres with at least one pressing arrangement, pushing the sides of said tyres from said edges towards said inner channels in such a way as to make them loose with respect to these, removing said tyres made loose from said edges, characterized by the fact that said pressing comprises moving said pressing arrangement towards said inner channels following their profile, in such a way that said pressing arrangement adapts between said inner channels and said sides of the tyres.

The pressing apparatus and the removal method therefore allow the pressing disc both to adapt to the type of tyre to be pressed and to follow the profile of the central channel of a rim during pressing on the tyre, in such a way as to automatically adapt between the rim and the bead of the tyre.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will appear more evident from the detailed description of a pressing apparatus, suitable for pressing the sides of tyres, illustrated indicatively by way of non limiting example, in the attached drawings wherein:

Figure 1 is a schematic side view of a tyre changing machine having a pressing device to press the sides of tyres;

Figure 2 is an interrupted and schematic side view on an enlarged scale of a pressing device fitted on the tyre changing machine of Figure 1; Figure 3 is an interrupted and schematic view of the pressing device of Figure 2;

Figure 4 is an interrupted and schematic side view of a pressing phase of a tyre bead for the removal from a rim.

EMBODIMENTS OF THE INVENTION

With reference to the Figure 1, by 1 is indicated a tyre changing machine that comprises a base 2 and a turret 3 that elevates from the base 2.

On an upper face 4 of the base 2 is fitted a rotating platform 5 on which can be rested and temporarily fastened wheels 6 of vehicles, indicated by the shape outlined by the broken lines, and which comprise a rim 116 and a tyre 126 fitted on this.

Along the turret 3, a supporting element 7 is movale up and down that extends towards the platform 5 with an end considered distal 107 while the opposite proximal end 207 is arranged sliding on vertical guides 8 integral with the turret 3 and indicated by the broken lines.

The supporting element 7 can be moved along the guides 8 by means of its actuators

9, normally comprising fluid mechanics cylinders. As can be seen from the Figure 1, on the tyre changing machine 1 a second supporting element 10 is provided, substantially supported parallel to the supporting element 7 and this too movale up and down along the guides 8, driven by its own actuators 11.

This second supporting element 10 also defines a distal end, indicated by 110, which is turned towards the platform 5 and an opposite proximal end 210. At the respective distal ends 107 and 110 both the supporting elements 7 and 10 bear pressing elements 12, mounted on these by means of arms 13 and 13'.

The arms 13 and 13' are supported at the respective supporting elements 7 and 10 in an oscillating way by means of hinge pins 14 arranged transversally in the supporting elements 7 and 10. The latter, with reference to the Figure 3, are composed of a pair of plates 15 parallel and tightened together by means of screw elements 16 which engage in a spacer

element 17 arranged between the plates 15.

Each arm 13 comprises a first section 13 A which is hinged to the hinge pin 14 and a second consecutive section 13B, slightly bent with respect to the first section 13 A and turned outwards which, at an end opposite the first section 13 A, supports a respective pressing element 12 which protrudes beyond the distal end of the second section 13B. The pressing element 12 comprises a disc 18 which is supported free to rotate on the section 13B according to a rotation axis "A" perpendicular to the second section 13B, and which defines a peripheral edge 118 intended to be placed in contact with a bead 106 of the tyre 126. Between one end of the first section 13 A opposite the second section 13B and the supporting element 7, a spring 19 is provided mounted on a spring guide 20, designed to contrast the oscillations of the arm 13.

The spring guide 20 has adjustable length, so as to be able to regulate the extent of the oscillations of the arm 13. At a central area of the first section 13 A, a selector device 21 is fitted which is equipped with an eccentric body 22 that has an outer surface and can be turned between a lock position in which the outer surface rests against the first section 13 A and a position of non intervention in which the eccentric body 22 is turned in a configuration in which the outer surface is moved away from the first section 13 A. The selector device 21 prevents the arm 13 from oscillating when it is turned in the lock position while, when it is turned in the away position, it allows the arm 13 to oscillate.

The operation of the pressing apparatus 12 is as follows: when the operator has to remove a tyre 126 from its rim 116, he/she deflates it and rests the wheel 6 on the work platform 5 of a tyre changing machine 1 and fastens it on this in a known way. Afterwards, the operator regulates the length of the arm 13 and the angular position of the support 7 so the peripheral edge 118 of the disc 18 is substantially aligned above the bead 106 of the tyre 126. The operator then operates the actuator 9 and brings the support 7 down towards the platform 5: this way, the disc 18 comes into contact with the bead 106 of the tyre 126 and gradually pushes this towards the central channel of the rim 116, indicated by

B2008/000894

216, as can be seen schematically in the Figure 4.

Beforehand, the operator checks to see whether the tyre 126 is of the normal or special type, i.e. whether the tyre 126 has beads 106 with reduced bending rigidity, i.e. whether they are easily deformable, or whether, on the contrary, the beads 106 are more rigid to bending.

In the first case, he/she operates the selector device 21, placing this in a position in which the eccentric body 22 is distant from the first section 13 A of the arm 13. In this position, the disc 18 can oscillate together with the arm 13 and can follow the inner profile of the rim 116 defined between the edge of this, indicated by 316, and the central channel 216, adapting itself automatically to the bending of the sides, following the deformations and placing itself in such a position as to introduce the peripheral edge 118 between the rim 116 and the bead 106 of the tyre 126, without any risk of damaging the edge 316 because it does not come into contact with this. Were it however to occur that the peripheral edge 118 come into contact with the rim 116, the disc 18 is dampened by the spring 19 which acts on the first section 13 A of the arm 13 and the contact force between the disc 18 and the edge 316 appears considerably limited and such as not to damage the rim 116.

When however the operator establishes that the tyre 126 is of the special type and that it has not very flexible beads, which are not therefore easily deformable by pressure, he/she turns the selector device 21 to a position locking the oscillation of the arm 13, in which the eccentric body 22 is kept resting against the first section 13A and consequently prevents any movement of the arm 13 which, in this case, behaves like a normal and known pressing device used on tyre changing machines 1.