Centering bladder mechanism of a vulcanising machine for tyre manufacture

Abstract

A centering bladder mechanism of a vulcanising machine for tyre manufacture comprising a central rod (1) on which an upper ring (2) and a lower ring (3) are movably arranged, between which a bladder (4) for vulcanising the inner surface of a tyre (5) is arranged in a steam-tight and watertight manner, a means for supplying a medium into the bladder (4) and a means for discharging the medium from the bladder (4), wherein the means for discharging / supplying the medium from / to the bladder (4) comprises at least two pipes (6) arranged along the central rod (1), symmetrically with respect to the longitudinal axis of the central rod (1), wherein each pipe (6) is arranged with one end inside the bladder (4) and with the other end outside the bladder (4). The means for supplying / discharging the medium into / from the bladder (4) is in the form of a channel (7) arranged on the axis of the central rod (1), and wherein the channel (7) opens out at one end inside the bladder (4) and at the other end outside the bladder (4), and wherein the medium supply terminates in a rosette.

Description

[0001] Centering bladder mechanism of a vulcanising machine for tyre manufacture

[0002] Technical field

[0003] The invention relates to the design of a centering bladder mechanism of vulcanising machines for tyre manufacture, specifically to the arrangement of the supply and discharge lines for the medium required for tyre vulcanisation through the centering bladder mechanism.

[0004] Background art

[0005] A tyre vulcanising press is an industrial device intended for the manufacture and retreading of tyres by a vulcanisation process. This process consists in the application of heat and pressure to a raw rubber compound or a tread layer; whereby chemical changes occur in the material and the final form of the tyre with the required properties is created. The vulcanising press also includes a centering bladder mechanism, which serves for the precise positioning of the green tyre in the mould of the vulcanising press and through which the medium required for tyre vulcanisation is supplied to the centre of the tyre, ensuring pressurisation of the inner side of the tyre. This mechanism also ensures the discharge of the said medium. The said medium provides the heat and pressure required for the tyre vulcanisation process to the bladder located inside the tyre, thereby helping to shape and vulcanise the inner surface of the tyre. Correct centring of the tyre is key to ensuring uniform distribution of pressure and heat, thereby preventing the occurrence of deformations and defects in the finished product.

[0006] At present, the centering bladder mechanism of the vulcanising machine is formed by a solid rod positioned on the axis of the centering bladder mechanism. The medium is supplied through a single supply pipe. The discharge of the medium from the bladder is also realised via a single discharge point on the circumference of the lower ring and subsequently by a discharge pipe of the same bore as the supply pipe. On the solid rod of the centering bladder mechanism, the lower and upper bladder ringsare movably arranged, between which a bladder is secured, which holds the tyre in the correct position before the mould is closed (pre-inflation). The rings are actuated by electric or hydraulic cylinders, which position them precisely in the mould. The centering bladder mechanism may also comprise position sensors, i.e. electronic sensors ensuring control of the precise placement of the tyre in the mould. A pneumatic or hydraulic levelling system ensures fine adjustment of the tyre position before the start of vulcanisation.

[0007] Before insertion of the tyre into the press, the centering bladder mechanism is in the open position, wherein the distance between the upper and lower ring is at its maximum. Inside the bladder there is a low vacuum. After the green tyre has been placed into the press, the centering bladder mechanism is moved into the working position (the vulcanisation position), where the upper ring approaches the lower ring. This position depends on the size and type of the tyre being vulcanised. The pressure in the bladder increases to approximately 0.5 bar. At this pressure, the tyre is stabilised in position, and the press can be closed. After the press has been closed, the pressure and temperature in the bladder are increased, by supply of the medium, to approximately 17 bar and approximately 180 °C, depending on the size and type of the tyre. After completion of vulcanisation, the pressure is reduced by discharging the medium from the bladder to 0.5 bar and the press is opened. The lower ring is moved upwards in order to pull the casing out of the sidewall and the tyre is removed.

[0008] The supply and discharge of the medium through the centering bladder mechanism is therefore implemented by two pipes arranged on the sides of the centering bladder mechanism. Through one pipe the medium flows in and through the other out. A disadvantage of this arrangement is that neither the supply nor the discharge of the medium from the centering bladder mechanism is arranged symmetrically with respect to the tyre axis / the axis of the centering bladder mechanism, which causes slight deformation of the bladder and thus also of the vulcanised tyre during filling of the medium into the bladder. Another disadvantage of this arrangement is that the flow of the medium through the centering bladder mechanism is limited by the cross-section of the pipes through which the medium flows into and out of the bladder. In existing solutions,3A” or at most 1" pipes are used for the supply and discharge of the medium. The design of the centering bladder mechanism is spatially constrained by the minimum dimension of the inner bead of the tyre, which is conceived for a certain tyre size, which does not allow the cross-section of the supply and discharge pipe to be increased.

[0009] The aim of this invention is to provide a centering bladder mechanism which eliminates the stated disadvantages of the prior art, i.e. has a greater medium flow rate, and does not cause deformation of the bladder and thus also of the vulcanised tyre during filling with the medium.

[0010] Summary of the invention

[0011] A centering bladder mechanism of a vulcanising machine according to this invention, which comprises a central rod on which an upper ring and a lower ring are movably arranged, between which a bladder for vulcanising the inner surface of the tyre is arranged in a steam-tight and watertight manner, a means for supplying a medium into the bladder and a means for discharging the medium from the bladder, characterised in that, either

[0012] - the means for discharging the medium from the bladder comprises at least two pipes arranged along the central rod, symmetrically with respect to the longitudinal axis of the central rod, wherein each pipe is arranged at one end inside the bladder and at the other end outside the bladder, and wherein - the means for supplying the medium into the bladder is in the form of a channel arranged in the longitudinal axis of the central rod, and wherein the channel is provided inside the bladder with a first outlet and outside the bladder with a second outlet, and wherein the first outlet is in the form of a rosette with symmetrically arranged openings for uniform supply of the medium into the bladder, or

[0013] - the means for supplying the medium into the bladder comprises at least two pipes arranged along the central rod, symmetrically with respect to thelongitudinal axis of the central rod, wherein each pipe is arranged at one end inside the bladder and at the other end outside the bladder, and wherein each end of the pipe opening into the bladder is provided with a rosette with symmetrically arranged openings for uniform supply of the medium into the bladder, and wherein

[0014] - the means for discharging the medium from the bladder is in the form of a channel arranged in the longitudinal axis of the central rod, and wherein the channel is provided inside the bladder with a first outlet and outside the bladder with a second outlet.

[0015] The advantage of this arrangement is that the medium flows into the bladder symmetrically with respect to the central axis of the tyre, either directly along the axis of the central rod of the centering bladder mechanism (on the central axis of the tyre being vulcanised) or simultaneously via two pipes arranged symmetrically with respect to that axis. This arrangement ensures that deformation of the bladder, and thus of the tyre, during filling with the medium is minimised. Further reduction of tyre deformation is also supported by the design of the rosette with symmetrically arranged openings for supplying the medium into the bladder.

[0016] With this arrangement of the medium supply and discharge lines, the flow rate of the medium into and out of the bladder is also doubled while retaining the original dimensions of the centering bladder mechanism. The higher flow rate of the medium ensures better heat transfer and also better circulation of the medium inside the bladder. The cross-sectional area of the channel should be essentially equal to the sum of the cross-sectional areas of the pipes, so that no resistance arises during circulation of the medium. The channel formed in the central rod may also have a flow rate twice that of the prior-art device. Likewise, the two lateral pipes ensure a flow rate twice that of the prior art (one pipe).

[0017] According to a preferred embodiment, the ends of the pipes for supplying or discharging the medium opening into the bladder are arranged in a single plane perpendicular to the longitudinal axis of the central rod. This means that theyterminate at the same level. At the same time, they are arranged symmetrically with respect to the axis of the central rod (the axis of the centering bladder mechanism).

[0018] According to a further preferred embodiment, the first outlet of the channel is offset from the ends of the pipes opening into the bladder. The first outlet of the channel is preferably located at most within 1 / 3 of the distance between the upper and lower ring in the working position of the centering bladder mechanism from the upper ring (in the upper third of the bladder), preferably as close as possible to the upper ring. The ends of the pipes opening into the bladder are preferably located at most within 1 / 3 of the distance between the upper and lower ring in the working position of the centering bladder mechanism from the lower ring (in the lower third of the bladder), preferably as close as possible to the lower ring.

[0019] According to a further preferred embodiment, the rosette is in the form of a tube and has the same and / or a different diameter as the pipes / channel of the central rod. The tubular rosette is closed off at one end and contains a plurality of openings arranged radially around the circumference of the tube, wherein the openings may be arranged in a single row (on one circle) or in multiple rows; alternatively, they may be arranged in a spiral around the circumference of the tube.

[0020] An advantage of the centering bladder mechanism according to this invention is that the symmetrical placement of the medium supply lines ensures uniform distribution of pressure and temperature in the bladder, thereby preventing deformations of the vulcanised tyre. The design of the centering bladder mechanism according to this invention also accelerates the vulcanisation process by increasing the flow rate of the medium into and out of the bladder.

[0021] Brief description of the drawings

[0022] Figure 1 shows the centering bladder mechanism according to this invention in the open position.Figure 2 shows the centering bladder mechanism according to this invention in the working position.

[0023] Detailed description

[0024] Example 1

[0025] The centering bladder mechanism of a vulcanising machine for tyre 5 manufacture, shown in Figure 1, comprises a central rod 1. An upper ring 2 and a lower ring 3 are movably arranged on the central rod 1, between which a bladder 4 for vulcanising the inner surface of the tyre 5 is arranged in a steam-tight and watertight manner. The central rod 1 is hollow and is provided with a channel 7 arranged on its longitudinal axis. The medium is supplied into the bladder 4 through this channel 7. The channel 7 opens out close to the upper ring 2 when the centering bladder mechanism, and thus also the bladder 4, is in the working position (Fig. 2). The centering bladder mechanism further comprises a means for discharging the medium from the bladder 4 in the form of two pipes 6 arranged along the central rod 1, symmetrically with respect to the longitudinal axis of the central rod 1. The ends of the pipes 6 are located close to the lower ring 3 when the bladder 4 is in the working position.

[0026] Example 2

[0027] The design of the centering bladder mechanism is the same as in Example 1, with the difference that two pipes 6 arranged along the central rod 1 serve to supply the medium into the bladder 4, and the medium is discharged from the bladder 4 through the channel 7 arranged in the central rod 1 (not shown).Reference signs:

[0028] 1 central rod

[0029] 2 upper ring

[0030] 3 lower ring

[0031] 4 bladder

[0032] 5 tyre

[0033] 6 pipe

[0034] 7 channel

[0035] 8 first outlet of the channel 9 second outlet of the channel

Claims

Claims1. A centering bladder mechanism of a vulcanising machine for tyre manufacture, comprising a central rod (1) on which an upper ring (2) and a lower ring (3) are movably arranged, between which a bladder for vulcanising the inner surface of a tyre (5) is arranged in a steam-tight and watertight manner, a means for supplying a medium into the bladder (4) and a means for discharging the medium from the bladder, characterised in that, either- the means for discharging the medium from the bladder comprises at least two pipes (6) arranged along the central rod (1), symmetrically with respect to the longitudinal axis of the central rod (1), wherein each pipe (6) is arranged with one end inside the bladder (4) and with the other end outside the bladder (4), and wherein- the means for supplying the medium into the bladder (4) is in the form of a channel (7) arranged on the axis of the central rod (1), and wherein the channel (7) is provided inside the bladder (4) with a first outlet (8) and outside the bladder (4) with a second outlet (9), and wherein the first outlet (8) of the channel (7) is in the form of a rosette with symmetrically arranged openings for uniform supply of the medium into the bladder (4), or- the means for supplying the medium into the bladder (4) comprises at least two pipes (6) arranged along the central rod (1), symmetrically with respect to the longitudinal axis of the central rod (1), wherein each pipe (6) is arranged with one end inside the bladder (4) and with the other end outside the bladder (4), and wherein each end of the pipe (6) opening into the bladder (4) is provided with a rosette with symmetrically arranged openings for uniform supply of the medium into the bladder (4), and wherein- the means for discharging the medium from the bladder (4) is in the form of a channel (7) arranged on the axis of the central rod (1), and wherein the channel (7) is provided inside the bladder (4) with a first outlet (8) and outside the bladder (4) with a second outlet (9).

2. The centering bladder mechanism of a vulcanising machine according to claim 1, characterised in that the ends of the pipes (6) opening into the bladder (4) are arranged in a single plane perpendicular to the longitudinal axis of the central rod (1).

3. The centering bladder mechanism of a vulcanising machine according to claim 1 or 2, characterised in that the first outlet (8) of the channel (7) is offset from the ends of the pipes (6) opening into the bladder (4), preferably the first outlet (8) of the channel (7) is situated in the upper third of the bladder (4) in the working position, more preferably in close proximity to the upper ring (2), and preferably the ends of the pipes (6) are situated in the lower third of the bladder (4) in the working position, more preferably in close proximity to or at the level of the lower ring (3).

4. The centering bladder mechanism of a vulcanising machine according to any of the preceding claims, characterised in that the rosette is in the form of a tube, closed off at one end and provided with a plurality of openings arranged radially around the circumference of the tube.

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