Vulcanizing press

The invention relates to a vulcanizing press comprising two plates capable of adopting a proximal position in which said plates close a mold, so as to give a tire a predetermined shape, and a distal position in which the mold is open; and at least one bore formed in one of said plates called the support plate, the diameter of said bore being defined so as to let the head of a pin pass thereinto. The vulcanizing press further includes a locking/unlocking device comprising a first movable stop that can move between a rest position and an active position, in which said stop is interposed between the head of the pin and the support plate in order to keep said pin in the bore, the shank of said pin being fixed to the mold.

BACKGROUND

Disclosed herein is a vulcanizing press for manufacturing a tire and a system for manufacturing a tire using such a vulcanizing press.

2. Description of Related Art

Document FR 1 570 554 discloses a vulcanizing press comprising a top plate and a bottom plate.

A mold, placed between the top plate and the bottom plate, enables a tire to be given a predetermined shape. More particularly, the top plate and the bottom plate are capable of adopting a proximal position in which said plates close the mold, in order to give the tire the predetermined shape, and a distal position in which the mold is closed.

As is known, the mold comprises an upper part and a lower part that are fixed to the top plate and to the bottom plate, respectively, using a set of pins and nuts.

To be able to form various types of tire having various characteristics (size, tread pattern, etc.) with the same vulcanizing press, it is possible to change mold by unclamping the various nuts and loading a new mold on the fixed plate. Such a mold-changing operation is often lengthy and irksome, since it is necessary for the nuts to be slackened and tightened manually. This operation is all the more tricky as sometimes the nuts are awkward to access for an operator.

There is therefore a need to optimize the time required to change a mold on a vulcanizing press for manufacturing tires.

SUMMARY

Disclosed herein is a vulcanizing press comprising two plates capable of adopting a proximal position in which said plates close a mold, so as to give a tire a predetermined shape, and a distal position in which the mold is open; at least one bore being formed in one of said plates called the support plate, the diameter of said bore being defined so as to let the head of a pin pass thereinto. The vulcanizing press further includes a locking/unlocking device comprising a first movable stop that can move between a rest position and an active position, in which said stop is interposed between the head of the pin and the support plate in order to keep said pin in the bore, the shank of said pin being fixed to the mold.

If the support plate is the top plate, the upper part of the mold is rapidly fastened to/unfastened from said top plate. If the support plate is the bottom plate, the lower part of the mold is rapidly fastened to/unfastened from said bottom plate. The invention may also be used both for the upper part of the mold and for the lower part of the mold so that it is possible for the entire mold to be rapidly fastened to/unfastened from the vulcanizing press.

The invention thus makes it possible to optimize the loading/unloading of a mold in a vulcanizing press.

According to one embodiment of the invention, the first movable stop has a cavity comprising a shoulder capable of coming into contact with the head of the pin; a hole, the diameter of which is defined so as to let the head of the pin pass thereinto; and a sliding zone extending between the shoulder and the hole.

The first movable stop allows the head of the pin to be locked when said stop is in the active position, while still making it possible for said head to slide in the bore when the first movable stop is in the rest position.

In one embodiment, the shoulder is offset heightwise relative to the sliding zone so as to prevent the head of the pin from moving in a direction parallel to the extension of said sliding zone when the first movable stop is in the active position.

The safety of the vulcanizing press is thus improved, while ensuring that the first movable stop is self-locked with the head of the pin when the first movable stop is in its active position. To move the first movable stop to its rest position, it is thus necessary to move the head of the pin vertically so as to bring the lower part of the head of the pin level with the sliding zone and then to move the first movable stop horizontally.

In one embodiment, the support plate comprises a resisting plate and a heating plate placed between the resisting plate and the mold, said press further including elastic means placed between the resisting plate and the heating plate in order to keep said heating plate in contact with the mold.

To be able to shift the head of the pin so as to bring the lower part of the head of the pin to the same level as the sliding zone, it is necessary to provide a clearance in the vulcanizing press. When this clearance is present between the head of the pin and the shoulder, the head of the pin is then at the same level as the sliding zone. When the head of the pin rests on the shoulder, that is to say when the pin is in its active position, the clearance is between the resisting plate and the heating plate. To maintain constant contact between the heating plate and the mold, elastic means placed between the resisting plate and the heating plate are used. This therefore ensures that the temperature of the mold is generally constant over time, even when the support plate is in its distal position. The vulcanizing time of the tire is thus optimized, since it is unnecessary at each mold closing/opening cycle to provide time to raise the temperature of the mold to the vulcanizing temperature.

In one embodiment, the sliding zone forms a ramp between the shoulder and the hole.

Thus, it is unnecessary to provide a particular clearance between the heating plate and the resisting plate. It is the slope of the sliding zone that allows the head of the pin to be locked/unlocked with respect to the shoulder.

In one embodiment, the first movable stop has two cavities.

It is thus possible to fix molds of different size to the vulcanizing press.

In one embodiment, the first movable stop comprises pivoting means about which a control rod for controlling the movement of a second movable stop can rotate.

The control rod serves to link two movable stops. It is thus possible to make the movement of these two movable stops mutually dependent, in order for the two parts of the mold to be fastened to and unfastened from the vulcanizing press.

In one embodiment, the press comprises four movable stops placed on the support plate so that each movable stop is opposite one of the other movable stops; three control rods, the control rods connecting the movable stops pairwise; and an actuator connected by linking means to one of said stops in order to control the movement of the various movable stops.

The coordinated movement of the various movable stops, for fastening several mold parts to the vulcanizing press and for unfastening them therefrom, can thus be easily controlled.

The vulcanising press containing plates and other features as disclosed herein thus makes it possible to optimize the time for changing a mold on a vulcanizing press.

Also disclosed herein is a system for manufacturing a tire comprising a vulcanizing press in accordance with the vulcanizing press described above, a mold placed between the plates of the vulcanizing press and at least one pin intended to fix the mold to the vulcanizing press.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

In the present description, the embodiments are described in conjunction with the use of molds of the sectorized type. However, it should straightaway be noted that the invention is not limited to the use of this type of mold but extends to other types of molds, such as two-part molds, called “shell molds”.

In the following description, substantially identical or similar elements will be denoted by the same references.

FIG. 1shows a partial sectional view of a system1for manufacturing tires. The system1comprises a vulcanizing press2having a top plate3and a bottom plate5. Here, the bottom plate5is fixed and the top plate3can move vertically. As a variant, it is possible for the top plate3to be fixed and the bottom plate to move vertically. All combinations of movement between the top plate and the bottom plate are possible.

The system1also comprises a mold11. The mold11is placed between the top plate3and the bottom plate5. Here, the mold11is divided into a plurality of mold parts13,15,17,19. In particular, the mold11comprises upper shells13and lower shells15. The mold11also comprises a plurality of sectors17capable of coming into contact with the upper shells13and lower shells15. The mold also comprises rings19designed to move the sectors17towards the upper shells13and lower shells15. The rings19are placed around sectors17and comprise a baseplate21and an upright23placed transversely with respect to the baseplate21. In cross section, the overall shape of the upright23is approximately triangular. To make the embodiment more easily understood,FIG. 1shows only a single upper shell13, a single lower shell15, a single sector17and a single ring19.

The embodiment applies here to the fastening of the ring19to the top plate3, called in the rest of the description the support plate3.

Of course, other embodiments may apply to fastening the lower shell15to the bottom plate5, the bottom plate5then being a support plate.

Here, the support plate3supports the ring19of the mold11. Here, it should be noted from now on that the upper shell13is supported here by a ram (not shown) belonging to the vulcanizing press2.

The support plate3moves between a proximal position with respect to the bottom plate5and a distal position with respect to said bottom plate5.

In the distal position as shown inFIG. 1, the various mold parts13,15,17,19are sufficiently far apart to be able to insert a tire to be vulcanized. Likewise, in this distal position, the various mold parts13,15,17,19are sufficiently spaced apart to be able to remove a vulcanized tire.

In the proximal position, the upper shells13, the lower shells15and the plurality of sectors17form a housing intended to enclose a tire in order to to vulcanize it.

Vulcanization is a manufacturing step that consists in changing the rubber of the tire from a plastic state to an elastic state. During this step, it is possible to form the pattern on the tire (grooves, incisions, etc.). To do this, the sectors17have on the inside particular molding elements (not shown).

It should be noted that the support plate3and the upright23have internal spaces10,24for the flow of a fluid heated to very high temperature, such as steam, for the purpose of heating the upper shell13, the lower shell15and the sector17.

The system1for manufacturing tires also includes at least one pin25placed in a bore27formed in the support plate3. The pin25comprises a head29and a shank31opposite the head. The shank31of the pin25is fixed here to the baseplate21of the ring19. The diameter of the bore27is defined so as to allow the head of the pin25to pass thereinto.

The vulcanizing press2includes a locking/unlocking device33comprising a first movable stop35athat can move between a rest position and an active position. InFIG. 1, the first movable stop35ais in the active position. In this active position, the first stop35ais interposed between the head29of the pin25and the support plate3so as to keep the pin25in the bore27.

The first movable stop35ais linked to an actuator37capable of moving said movable stop35a. More particularly, the first movable stop35ahere can slide on a retaining plate39connected to the frame of the actuator37.

It should be noted that the support plate3comprises a resisting plate7and a heating plate9.

The resisting plate7is that part of the support plate3which is connected to a ram63for moving said support plate3vertically.

The heating plate9includes internal spaces10for the flow of the fluid heated to very high temperature.

There is a clearance C between the resisting plate7and the heating plate9when the support plate3is in the distal position shown inFIG. 1.

When the support plate3is in its proximal position, the clearance C between the resisting plate7and the support plate3disappears. This clearance C is between the head29of the pin25and the shoulder49, thereby enabling the first movable stop35ato move towards its rest position.

It should also be noted inFIG. 1that there are elastic means55, which is a biasing element, desirably of the compression spring type, between the resisting plate7and the heating plate9. These elastic means55enable the heating plate9to be kept in contact with the baseplate21of the ring19while still maintaining a certain distance between the heating plate9and the resisting plate7when the support plate is in the distal position. Thus, the heat transfer between the heating plate9and the baseplate21is improved and heat loss between the heating plate9and the resisting plate7is avoided.

Likewise, the elastic means enable the heating plate9to be brought back into contact with the baseplate21when the support plate3leaves the proximal position since in this instant it may happen that the heating plate9jams between the resisting plate7and the baseplate21owing to the effect of the movement of the support plate3. It is therefore necessary to provide these elastic means55for bringing the heating plate9back against the baseplate21.

FIG. 2shows a perspective view of a first example of a first movable stop35a. Here, the first movable stop35acomprises a cylindrical part41and a flat43in one piece with the cylindrical part41.

The part41has a first cavity45and a second cavity47identical to the first cavity45. The second cavity47is away from the first cavity45in the length direction of the first movable stop35a, i.e. in a horizontal direction X. The locking/unlocking device33can thus adapt to various sizes of the mold11.

Each cavity has a shoulder49designed to come into contact with the head29of the pin25, a hole51and a sliding zone53extending between the shoulder49and the hole51.

The hole51has a defined diameter so as to let the head29of the pin25pass thereinto.

The sliding zone53is a smooth surface so as to make it easy for the head29of the pin25to slide when the first movable stop35amoves from the active position to the rest position.

To keep the pin25in the bore27when the first movable stop35is in the active position, provision is made for the sliding zone53to extend along the horizontal direction X and for the shoulder49to be offset heightwise, that is to say offset in a vertical direction Z relative to the sliding zone53. The head29of the pin25is thus prevented from moving in the horizontal direction X. The safety of the manufacturing system1is therefore improved by ensuring that the first stop35ais self-locked with the head29of the pin25when the first movable stop35ais in its active position.

To move the first movable stop35ato its rest position, the head29of the pin25must be shifted upwards relative to the shoulder49so as to bring the lower part of the head29to the same level as the sliding zone53. When the lower part of the head29reaches this level, the actuator37can move the first movable stop35ato its rest position. This upward shift of the head29of the pin25is possible when the support plate3is in its proximal position because of the absence of the clearance C between the resisting plate7and the heating plate9and the presence of said clearance C between the head of the pin25and the shoulder49.

FIG. 3shows another embodiment of the first movable stop35a. In this embodiment, the sliding zone53forms a ramp between the shoulder49and the hole51. It is then unnecessary to provide a particular clearance between the resisting plate7and the support plate3, since it is the slope of the ramp that makes it possible for the head29of the pin25to be blocked against the first movable stop35aat the shoulder49.

Of course, the invention is not limited to these two particular embodiments of the first movable stop35a, rather it encompasses all equivalent embodiments.

For example, the first movable stop35amay be provided in the form of a fork having two arms. The two arms are spaced apart by a distance smaller than the diameter of the head of the pin. In the active position of the first movable stop35a, the arms are interposed between the head29of the pin35and the support plate3so as to keep said pin25in the bore27. In the rest position of the first movable stop35a, the arms are offset relative to the head29of the pin25.

In another example, the first movable stop may be designed to undergo a rotational movement so as to pass from an active position to a rest position, instead of a translational movement as in the previous examples. The first movable stop may then be in the form of a cam that can be interposed between the head29of the pin25and the support plate3in the active position, following a rotation from the rest position.

FIG. 2shows, on the flat43, pivot means57about which a control rod can rotate.

FIGS. 4aand4bshow in greater detail the operation of such a control rod.

More particularly,FIGS. 4aand4bshow a locking/unlocking device33comprising four movable stops35a,35b,35cand35dextending along axes Xa, Xb, Xc and Xd on the support plate3. In the illustrated embodiment, the support plate takes the form of a disk and the movable stops35a,35b,35cand35dare placed on the support plate3so that the axes Xa, Xb, Xc and Xd intersect at the center O of the support plate3. In the illustrated embodiment, each movable stop is placed opposite another movable stop.

The locking device33also includes three control rods59a,59band59c. Each control rod links two movable stops so that the first control rod59alinks the first movable rod35ato a second movable stop35b, the second control rod59blinks the second movable stop35bto a third movable stop35c, and the third control rod59clinks the third movable stop35cto a fourth movable stop35d.

The first movable stop35ais linked to the actuator37by linking means or linkage61.

It should be noted that in the illustrated embodiment there are two types of movable stop. The first movable stop35aand the third movable stop35cin which the holes51aand51care closer to the center O than the shoulders49aand49c, belong to a first type. The second movable stop35band the fourth movable stop35d, in which the holes51band51dare further away from the center O than the shoulders49band49d, belong to a second type.

InFIG. 4a, the various movable stops35a,35b,35cand35dare all in their rest positions.

InFIG. 4b, the various movable stops35a,35b,35cand35dare all in their active positions. The movement from the rest positions to the active positions is accomplished by means of the actuator37. Specifically, when the actuator37moves the first movable stop35afrom the position shown inFIG. 4ato the position shown inFIG. 4b, the first movable stop35ais directed towards the center O of the support plate3. The rod59adrives the second movable stop35baway from the center O. The rod59bthen drives the third movable stop35ctowards the center O and the rod59cdrives the fourth movable stop35daway from the center O.

By virtue of the locking/unlocking device33shown inFIGS. 4aand4b, it is possible to move the various movable stops35a,35b,35cand35dusing a single actuator37.

We will now present with greater detail, usingFIGS. 5a,5b,5cand5d, one method of removing a mold.

FIG. 5ashows the support plate3in the distal position ofFIG. 1. The ring19, the upper shell13and the lower shell15are spaced apart. In this position, the mold is “open”.

FIG. 5bshows the support plate3in its proximal position. The sector17is in contact with the upper shell13and the lower shell15. In this position, the mold11is “closed”.

To move from the position shown inFIG. 5ato the position shown inFIG. 5b, the ram63acts on the resisting plate7so as to move the ring19towards the lower shell15. The upper shell13is moved coordinately towards the lower shell15by another ram (not shown). The ring19is designed so that its vertical movement towards the lower shell15causes the sector17to move horizontally towards the upper shell13and the lower shell15.

It should be noted that in the configuration shown inFIG. 5b, the elastic means55are compressed and the clearance C is between the head29of the pin and the first movable stop35a.

InFIG. 5c, the first movable stop35ais in its rest position after a movement of the actuator37. In this rest position, the pin25is in the hole51of the first movable stop35a.

FIG. 5dshows a position in which the support plate3is back in its distal position. The support plate3is then disconnected from the mold11since the head29of the pin25has not been retained in the bore27. It is then possible to remove the mold from the vulcanizing press from the position shown inFIG. 5d.

Also disclosed herein is a method of mounting a mold on the vulcanizing press. This method includes a step of loading the mold on the bottom plate so as to position heads of pins relative to bores formed in the support plate. The mounting method also includes a step of moving the support plate towards the proximal position so as to make the heads of the pins penetrate into the respective bores. In the proximal position, the movable stops are moved towards their active position so as to lock the heads of the pins and fix the mold to the vulcanizing press.

The invention having been described according to certain specific embodiments, it will be understood that these embodiments are illustrative and do not limit the scope of the appended claims.