FR2964593A1 - Tire manufacturing device for use in extrusion device i.e. slubbing machine, to manufacture tire of wheel of light vehicle, has heating unit that is rigidly fixed to frame, where heating unit extends in cavity of actuating unit - Google Patents

Abstract

The device (2) has an actuating unit (18) that is moved with respect to a frame (5). A heating unit (14) i.e. electric heating unit, is rigidly fixed to the frame, where the heating unit extends in a cavity of the actuating unit. The actuating unit is rotated with respect to the frame. An air space (26) extends between the actuating unit and the heating unit. The actuating unit is rotatably assembled. The heating unit extends from a shaft (6), where a section of the shaft extends opposite to the actuating unit.

Description

The invention relates to the manufacture of vehicle wheel tires. The manufacture of a tire passes through the realization of a blank formed by the assembly of different components, including strips or strips of raw gum. These are made by means of an extrusion device in which an externally threaded rotating roller or roller forces bulk gum to pass through a forming orifice. These rollers or rollers are heated internally by a water circuit. Indeed, the heating of the rubber during extrusion increases its plasticity.

But it is necessary to provide a seal and a rotating joint for connecting the rotating circuit of the roller to the fixed part of the machine from which the water supply is made. It is also necessary to connect the entire machine to a water circuit of the manufacturing plant. These disadvantages make the machine particularly expensive, generate maintenance operations and complicate the integration of the tool in question on a robot. An object of the invention is to simplify the tire manufacturing devices, equipped with heating means. For this purpose, provision is made according to the invention for a device for manufacturing a tire, which comprises: - a frame, - an actuator movably mounted relative to the frame, and - at least one heating element rigidly fixed to the constructed and extending into a cavity of the actuating member.

The integration of the fixed heater is much simpler, less expensive and naturally without risk of leakage even if the heater uses water. If the actuating member is rotatable, this solution does not require a rotating joint between the heater and the fixed part of the machine. A rotary joint of simple structure suffices.

For example, the actuating member is rotatably mounted relative to the frame. Advantageously, the or each heating member is an electric heating member. The use of an electric heating element is made possible in particular by the fact that it seeks only to heat the actuating member so that it transmits heat to the rubber and that it is not necessary to provide specific means to cool it. Indeed, the actuating member is permanently cooled in contact with the rubber which travels over its surface. This simpler solution is therefore advantageous over the aforementioned water circuit solution in which it tends rather to maintain the tool at the temperature of the water than simply warm it. In addition, the energy efficiency of this solution is much better than that of the water circuit. Indeed, it requires to bring hot water from outside the machine, sometimes from a place at a great distance. The hot water must therefore travel all the way. If the energy efficiency of the heat exchange is very good locally at the tool, it is generally poor given the heat losses that occur throughout the course of the hot water. With the electric heater, heat is generated only at the tool where it is needed. Preferably, the device has an air space extending between the actuating member and the or each heating member.

Thus, the heat transfer is done, at least in part or even mainly, by convection of air in this space. In one embodiment, the device comprises a shaft on which the actuating member is rotatably mounted, the or each heating member extending in the shaft.

In another embodiment, the device comprises a shaft on which the actuator is rotatably mounted, the or each heater extending out of the shaft. In one embodiment, the section of the shaft carrying the or each heating member extends opposite the actuating member.

In another embodiment, the device comprises a thermal conduction piece extending between the actuating member on the one hand and the or each heating member and the shaft on the other hand. This piece thus ensures the transfer of heat by conduction between these elements.

Preferably, the device comprises a temperature measuring member, such as a thermocouple, a pyrometer or a thermal camera. Advantageously, the device comprises means for controlling the or each heating element adapted to regulate a temperature of the actuating member.

In one embodiment, the invention forms an extrusion device. Other features and advantages of the invention will become apparent in the following description of two embodiments given by way of non-limiting example with reference to the accompanying drawings, in which: FIG. 1 is a sectional view axial axis of a roller of an extrusion device according to a first embodiment of the invention; FIG. 2 is a cross-sectional view along plane II-II of the roller of FIG. 1; and - Figures 3 and 4 are views similar to Figures 1 and 2 showing a second embodiment. The device 2 according to the invention forms in this case an extruder of a roll nose. The latter is used for the manufacture of a green rubber blank 10 for the production of a tire. The extruder allows the manufacture of a strip or tape of raw gum. FIG. 1 illustrates the tampering roller which, in this extruder, forces the rubber to pass through a forming orifice. The roller 4 is mounted on a shaft 6 which in this case is rigidly fixed to a frame 5 or base of the machine. This shaft 6 has a longitudinal axis 8 and a cylindrical outer face 10. The shaft 6 is hollow and has an internal cavity 12. In it are housed heating members 14 each formed in this case by a cartridge comprising a electrical resistance. The latter is suitably connected by means of a circuit 16 to an electrical installation of the machine. The cartridges 4 are here four in number, regularly distributed around the axis 8 and identical to each other. Each cartridge has a rectilinear elongate shape. The cartridges are rigidly fixed to the shaft 6 by being applied against an inner face thereof, parallel to the axis 8. The cartridges 14 extend in a middle portion 25 of the shaft 6. The roller 4 comprises a main cylindrical wall 18 of axis 8 having an inner face 20 and an outer face 22, both cylindrical with an axis 8. The roller here forms the actuating member and is rotatably mounted relative to the shaft 6 , in this case by means of two bearings 24 forming bearings 30 each interposed in the radial direction between the outer face of the shaft 6 and the inner face 20 of the wall 18 with which they are in contact. The roller is rotated by non-illustrated means. The two bearings 24 extend at the end portions of this shaft and are offset in the axial direction relative to the cartridges 14.

An air space 26 of cylindrical shape is formed between the outer face of the shaft 6 and the inner face 20. This space is left completely free to the right of the cartridges. In this space, the outer face of the shaft extends facing and at a distance from the inner face 20 of the wall 18. During operation, the wall 18 is rotated about the axis 8 relative to the shaft 6 as indicated by the arrow 30 of Figure 2. The outer face 22 is in contact with the raw green gum. Thanks to a thread formed on this face, the roller drives the material parallel to the axis 8 to force it through the extrusion orifice. The heating cartridges 14 produce heat which is transmitted to the wall of the shaft 6 and then to the air of the space 26. In this space, the heat is transmitted by convection of air to the wall 18 through its inner face 20 and escapes from its outer face to heat the rubber.

It is noted that the shaft and the heaters are stationary while the wall 18 is rotatable. In addition, the shaft 6 and the heating members are not in contact with the material. The device comprises a member such as a thermocouple 32 disposed in this case inside the shaft 6 in the space between two of the cartridges 14. It can measure the temperature prevailing within the shaft and to deduce the temperature at the outer face 22 of the wall 18. The machine comprises temperature control means 34 adapted to control the operation of the heating members 14 according to the signals transmitted by the thermocouple 32.

It is also possible to provide a pyrometer 36 and / or a thermal camera 38, both of which are connected to the control members 34. Each of them is able to measure a temperature of the external face 22 of the cylinder in order to improve the quality of the temperature regulation. A second embodiment of the invention is illustrated in Figures 3 and 4. Most features of this mode are common with those of the first mode. The device, however, also has a heat conduction member 40 extending into the cavity of the roller. This piece has, in this case, a cylindrical shape of axis 8 and is interposed radially between the shaft 6 and the wall 18. The part 40 is in contact by its inner face with the outer face 10 of the shaft so as to be carried by the latter and rigidly fixed thereto. The piece 40 is hollow and it is this which contains this time the heating members 40. The shaft 6 is therefore devoid of it. The part 40 thus extends between the actuating member 18 on the one hand and the heating members 14 and the shaft on the other hand. The power supply son of these members pass through the shaft 6 to join the control means as before. The members 14 are contiguous with the outer cylindrical wall of the piece 40. The latter is made of a good heat conducting material, for example copper. The air space 26 is this time limited to the volume formed between the outer face of the conduction piece 40 and the inner face 20 of the wall 18. The piece 40 extends in effect opposite and distance from it. In this way, heat transfer from room 40 to wall 18 is by convection through space 26. The other aspects of the installation and its operation are unchanged. This time, the heat produced by the heating members in the room 40 is transmitted through the outer wall of the latter, then through the space 26 and finally through the face 20 in the wall 18 to emerge from that by the face 22.

In this mode, the presence of the conduction part 40 makes it possible to reduce the heat losses, in particular because the air space is reduced. The main criterion involved in the choice of the material of the conduction part 40 is its good conductivity of heat. Indeed, because of its assembly, this part is not mechanically solicited. It is therefore not necessary to provide a material which has good resistance to mechanical stresses. It will be advantageous to implant at least one thermally insulating ring between the conduction part 40 and the shaft 6 in order to limit the heat transfer between them and preserve the bearings 24 thermally.

In these embodiments, the resistors are pencil resistors of 150 watts each operating at a nominal voltage of 220 volts. To avoid the use of a transformer, they are connected under 400 volts in two groups and coupled in star. The resistors are protected by means of a circuit-breaker on each group in order to detect, by means of its tripping, a possible breaking of the resistors. The control means 34 preferably provide proportional-integral temperature control. These control means may comprise electronic and / or computer devices such as microprocessors, memories, etc. and at least one program recorded on a recording medium and for controlling the operation of the machine when it is executed. These embodiments, particularly the second, avoid excessive heat loss. In the absence of rotation of the heating elements, it is not necessary to provide a rotary joint for the electric wires feeding these last 35, and these son, as we have seen, can even pass through the interior of the tree. The air space 26 compensates for the effects of thermal expansion. In addition, it is possible to provide a slight clearance between the parts to compensate for this effect in other places. The invention thus makes it possible to heat a rotating part without direct contact with it. It will be preferable to give the cartridge carrying part a high thermal conductivity in order to obtain a homogeneous distribution of the heat released by the cartridges. More generally, if the invention is particularly suitable for extruders or extruders, it is not limited to the latter. It can also be used in a roll of a roller table, a calender, or other types of working tools, all these devices used for the manufacture of a tire. The tires are intended for light-duty vehicle wheels, passenger vehicle vehicles, commercial vehicles, heavy vehicles, or civil engineering wheels.

Of course, many modifications can be made to the invention without departing from the scope thereof. The electric heating elements may be replaced by heating elements of another type, for example with a water circuit.

Claims (10)

REVENDICATIONS1. Device (2) for manufacturing a tire, characterized in that it comprises: - a frame (5), - an actuating member (18) movably mounted relative to the frame, and - at least one heating element (14) rigidly fixed to the frame and extending into a cavity of the actuating member. 2. Device according to the preceding claim wherein the actuating member (18) is rotatably mounted relative to the frame, 3. Device according to at least one of the preceding claims wherein the or each heating member (14) is an electric heating member. 4. Device according to at least one of the preceding claims, which has an air space (26) extending between the actuating member (18) and the or each heating member (14). 5. Device according to at least one of the preceding claims, which comprises a shaft (6) on which the actuating member (18) is rotatably mounted, the or each heating member (14) extending in the 'tree. 6. Device according to at least one of claims 1 to 4, which comprises a shaft (6) on which the actuating member (18) is rotatably mounted, the or each heating member (14) extending out of the tree. 7. Device according to at least one of claims 5 to 6 wherein the section of the shaft (6) carrying the or each heating member (14) extends opposite the actuating member (18). ). 8. Device according to at least one of the preceding claims, which comprises a heat conduction piece (40) extending between the actuating member (18) on the one hand and the or each heating member (14). ) and the tree on the other hand. Apparatus according to at least one of the preceding claims which comprises a temperature measuring member such as a thermocouple (32), a pyrometer (36) or a thermal camera (38), and preferably means (34) for controlling the or each heating member (14) able to regulate a temperature of the actuating member (18). 10. Device according to at least one of the preceding claims, forming an extrusion device.