METHOD FOR PRODUCING A MOLDING ELEMENT HAVING AN AIR DISCHARGE SLOT

Abstract

A moulding element (1) intended to be assembled in a mould for a tyre, said moulding element (1) comprising a moulding surface (2), and an external surface (3), venting means (4) designed for venting a flow of air from the moulding surface (2) towards the external surface (3), said venting means (4) comprising a first part (5) opening onto the moulding surface (2) and a second part (6) in communication with the first part (5) and opening onto the external surface (3), the first part (5) forming a path that is closed on itself, is produced by a method comprising the following steps: a step of creating the second part (6) in the moulding element; and a step of creating the first part (5) in the moulding element using a laser.

Claims

1.-10. (canceled)

11. A method for producing a molding element intended to be assembled in a mold for molding a tire, the molding element comprising a molding surface designed for molding part of the tire, an external surface opposite to the molding surface, venting means suited to discharging a flow of air from the molding surface toward the external surface, the venting means comprising a first part of width L1 between 0.03 mm and 0.07 mm and of depth P1 less than or equal to 3 mm, the first part opening onto the molding surface, and a second part in communication with the first part and opening onto the external surface, a width L2 of the second part being between 1 mm and 5 mm, the first part forming a path that is closed on itself, the method comprising the steps: (i) creating the first part in the molding element using a laser, the first part having a longitudinal axis A1; and (ii) creating the second part in the molding element, the second part being in communication with the first part, and the second part having a longitudinal axis A2, wherein the step of creating the second part is performed before the step of creating the first part, and wherein steps (i) and (ii) are performed in such a way that the axis A2 of the second part and the axis A1 of the first part are spaced apart by an offset D of at least 0.5 mm.

12. The method according to claim 11, wherein steps (i) and (ii) are performed in such a way that the axis A2 of the second part and the axis A1 of the first part are spaced apart by an offset D of at least 1 mm.

13. The method according to claim 11, wherein the first part forms a polygonal, circular or oval path.

14. The method according to claim 11, wherein the first part is produced by waterjet-guided laser.

15. The method according to claim 11, wherein the second part is produced by drilling or by machining.

16. The method according to claim 15, wherein the first part and the second part are produced on five-axis machines.

17. The method according to claim 11, wherein the second part is a cavity.

18. The method according to claim 11, wherein the second part is a groove.

19. The method according to claim 11, wherein the first part is a slot.

20. The method according to claim 19, wherein the depth P1 of the slot is 0.1 to 1 mm greater than a thickness EP of a wall resulting from a machining operation.

Description

DESCRIPTION OF THE FIGURES

[0024] All the embodiment details are given in the following description, which is supplemented by FIGS. 1 to 4b, which are given solely by way of non-limiting examples and in which:

[0025] FIG. 1 is a perspective view of one embodiment of a moulding element with a venting means;

[0026] FIGS. 2a and 2b schematically illustrate one example of an arrangement that is not suitable for creating a venting means;

[0027] FIGS. 3a and 3b schematically illustrate one example of an arrangement that is suitable for creating a venting means;

[0028] FIGS. 4a and 4b schematically illustrate embodiment variants with various relative dispositions of the first and second part of the venting means.

DETAILED DESCRIPTION OF THE INVENTION

[0029] FIG. 1 illustrates an exemplary embodiment of a portion of a moulding element 1 in which a venting means 4 connects a moulding surface 2 and an external surface 3 of said moulding element 1. The venting means comprises a first part 5 and a second part 6 in communication with one another. The first part 5 opens onto the moulding surface 2. The second part 6 opens onto the external surface 3.

[0030] As illustrated in FIGS. 3a, 4a and 4b, the two ends 8, 9 of the first part are joined together, forming a path that is closed on itself. The slot of the first part forms a polygonal path, for example in the shape of a square or of a circle (as illustrated in the example of FIG. 3a), an oval, a hexagon, a triangle, a rectangle (as illustrated for example in FIGS. 4a and 4b), a pentagon, a heptagon, an octagon, a nonagon, a decagon, a hendecagon, a dodecagon, a lozenge, a trapezium, a parallelogram, or any other shape in which the two ends 8, 9 are closed on one another.

[0031] The first part 5 has a depth P1 which is 0.1 mm to 1 mm greater than the thickness EP of the wall resulting from the machining, as illustrated in FIG. 1. These dimensions make it possible to ensure that the two parts really do communicate with one another.

[0032] In this exemplary embodiment, the first part is produced using waterjet-guided laser. The width of the first part 5 is comprised between 0.03 mm and 0.07 mm, and its depth P1 is less than or equal to 3 mm. This depth corresponds to the limit of precision sufficient for creating the first part 5. Beyond 3 mm, the waterjet-guided laser could yield results that are not sufficient to ensure that the first part is produced under optimal conditions.

[0033] The width L2 of the second part 6 is between 1 mm and 5 mm, and more preferably between 2 mm and 3 mm.

[0034] The method for producing the moulding element 1 comprises the following steps, performed successively in the following order: [0035] a) production of the second part 6 in the moulding element, [0036] b) production of the first part 5 in the moulding element using a laser, so that the first part 5 and the second part 6 are in communication.

[0037] The first part 5 is produced after the second part 6 so as to prevent any machining or cutting chips or scrap from obstructing the first part if the latter were produced before the second part. Conversely, the chips of material resulting from the creation of the first part 5 after the second part 6 do not carry the risk of blocking said second part 6 given its large dimensions in comparison with the first part 5. Steps a and b are formed in such a way that the respective longitudinal axes A1 and A2 of the first part 5 and of the second part 6 are spaced apart by an offset D of at least 0.5 mm, preferably 1 mm. This offset D between the two parts makes it possible to avoid situations like the one illustrated in FIG. 2a in which the two parts are aligned. In such situations, the first part 5 is entirely released, without any contact with the rest of the moulding element. This situation, which does not conform, leads to a manufacturing defect.

[0038] The second part 6 is produced by drilling, using a cone drill bit for example. In a variant, the second part 6 is produced by machining, using a flat-ended milling cutter for example, and/or on a five-axis machine. In the exemplary embodiments, the second part 6 is a cavity, as illustrated in FIGS. 1 to 3b. In a variant, the second part 6 is a groove, as illustrated in FIGS. 4a and 4b.

[0039] In FIGS. 1 to 4b, the first part 5 is a slot forming a path the two ends 8 and 9 of which meet.

[0040] FIGS. 3a and 3b illustrate an exemplary embodiment of the slot with respect to the drilling of the second part 6. As illustrated, the second part 6 is axially offset with respect to the first part 5. The two parts may be offset by greater or lesser amounts, provided that at least a zone of each of the two parts 5 and 6 is in contact one with the other, ensuring that the first part is held in place.

[0041] FIGS. 4a and 4b illustrate exemplary embodiments of the first part 5 in the shape of a rectangle. In FIG. 4a, the first part 5 is axially offset slightly with respect to the second part and this second part 6 is in the form of a groove 6. One single first part 5 communicates with one single second part 6. In a variant, in the example of FIG. 4b, the first part 5 is in communication with two distinct second parts 6

TABLE-US-00001 Reference numerals employed in the figures 1 Moulding element 2 Moulding surface 3 External surface 4 Venting means 5 First part 6 Second part 7 Central core of the first part 8 First end 9 Second end 10 Wall resulting from the machining