MOULD AND PROCESS FOR VULCANISING TYRES FOR VEHICLES WHEELS

Abstract

A mould for vulcanising tyres for vehicle wheels, comprising—at least one sidewall plate (3) on which a moulding surface (4) is defined,—a removable insert (10) arranged to be received in a seat (5) which is made in said sidewall plate and open on said moulding surface, said insert comprising a main body (11; 111) on which a base surface (12) is defined which is intended for contacting a portion of a sidewall (52) of the green tyre, and—a retaining member (20) for retaining said insert (10) inside said seat. The retaining member comprises at least one locking element which is mounted on one out of said insert and said sidewall plate and can be moved in an operating direction (Y) between a locking position, in which said insert is retained inside said seat, and a release position, in which said insert is free to leave said seat.

Claims

1. Mould (1; 100) for vulcanising tyres for vehicle wheels, comprising: at least one sidewall plate (3) on which a moulding surface (4) is defined which is intended for contacting an axially external surface of a sidewall (52) of a green tyre (50), a removable insert (10) arranged to be received in a seat (5) which is made in said sidewall plate and open on said moulding surface, wherein said insert comprises a main body (11; 111) on which a base surface (12) is defined which is intended for contacting a portion of said external surface of said sidewall (52) of the green tyre, and a retaining member (20) for retaining said insert (10) inside said seat (5), wherein said retaining member (20) comprises at least one locking element (21; 121) which is mounted on one out of said insert (10) and said sidewall plate (3) and comprises a first contact surface (22a; 103) for contacting the other out of said insert and said sidewall plate, and wherein said at least one locking element (21; 121) can be moved in an operating direction (Y), which is incident with respect to an insertion direction (X) of said insert into said seat, between a locking position, in which said insert is retained inside said seat, and a release position, in which said insert is free to leave said seat.

2. Mould according to claim 1, wherein, in said locking position, said insert (10) is retained inside said seat (5) by said first contact surface (22a; 103) such that said base surface (12) is substantially continuous with said moulding surface (4).

3. Mould according to either claim 1 or claim 2, wherein said retaining member (20) comprises a resilient element (23; 123) for urging said locking element (21; 121) towards said locking position.

4. Mould according to claim 3, wherein said resilient element (23; 123) is received inside a channel (24; 124) which extends in said operating direction (Y) and is open in said seat (5).

5. Mould according to any one of the preceding claims, wherein said locking element (21; 121) is fixed to said sidewall plate (3) and, in said locking position, projects into said seat (5) so as to engage said insert (10).

6. Mould according to any one of the preceding claims, wherein said insert (10) comprises a rod (13; 113) which extends in said insertion direction (X), on the opposite side to said base surface (12), and said first contact surface (22a; 103) engages said insert at said rod (13; 113) in order to retain said insert (10) in said seat (5).

7. Mould according to any one of the preceding claims, wherein said retaining member (20) comprises a plurality of said locking elements (21) arranged equiangularly around said seat (5).

8. Mould according to any one of the preceding claims, wherein said locking element (21) comprises a sphere (22) on which said first contact surface (22a) is defined.

9. Mould according to any one of claims 6 to 8, wherein a first shoulder (17) is defined on said rod (13), which shoulder is: oriented so as to diverge away from said main body (11), inclined with respect to a longitudinal axis (X) of said rod by an angle of between 10° and 70°, preferably between 20° and 40°, and positioned so as to contact said first contact surface (22a) when said locking element (21) is in the locking position.

10. Mould according to claim 9, wherein a second shoulder (19) is defined on said rod (13), which shoulder is: oriented so as to diverge towards said main body (11), inclined with respect to a longitudinal axis (X) of said rod (13) by an angle of between 10° and 70°, preferably between 20° and 40°, and positioned on the opposite side to said main body (11) with respect to said first shoulder (17).

11. Mould according to either claim 9 or claim 10, wherein said plurality of locking elements (21), when in the locking position, engages said rod at said first shoulder (17).

12. Mould according to any one of the preceding claims, wherein a passage (25) is formed on said sidewall plate (3), which passage connects said seat (5) to the outside of said mould so as to allow an operator to insert a manoeuvring tool (26) that is able to contact said insert and remove said insert (10) from said seat (5).

13. Mould according to claim 12, wherein said passage (25) extends substantially perpendicularly to said insertion direction (X).

14. Mould according to any one of the preceding claims, wherein said locking element (121) is fixed to said sidewall plate (3) and said first contact surface (103) contacts said insert (10) and moves said insert in said insertion direction (X) inside said seat (5) further to the movement of said locking element in said operating direction (Y).

15. Mould according to claim 14, wherein said first contact surface (103) is inclined with respect to said operating direction (Y) by an angle of between 15° and 45°.

16. Mould according to either claim 14 or claim 15, wherein said locking element (121) comprises a second contact surface (104) that contacts said insert and moves said insert in said insertion direction (X) towards the outside of said seat (5) further to the movement of said locking element (121) towards said release position.

17. Mould according to claim 16, wherein said first contact surface (103) and said second contact surface (104) are substantially parallel to one another.

18. Mould according to either claim 16 or claim 17, wherein said first contact surface (103) and said second contact surface (104) delimit a slot (52) which is formed on said locking element and is externally open in order to engage and release said insert when said locking element is moved in said operating direction (Y) between said locking position and said release position.

19. Mould according to any one of claims 14 to 18, wherein said locking element (121) comprises a threaded pin (105) which can be engaged by a manoeuvring tool in order to move said locking element (121) in said operating direction (Y) inside said channel (124).

20. Process for producing a tyre for vehicle wheels, comprising: building a green tyre (50), and moulding and vulcanising said green tyre (50) in a mould (1; 100) according to any one of the preceding claims.

Description

[0083] The characteristics and advantages of the invention will become clearer from the detailed description of a number of preferred exemplary embodiments thereof, illustrated by way of indication and in a non-limiting manner with reference to the accompanying drawings, in which:

[0084] FIG. 1 is a schematic, partial, cross-sectional view of a mould for vulcanising tyres for vehicle wheels formed according to a first exemplary embodiment of the present invention;

[0085] FIG. 2 is a schematic view on an enlarged scale of a component of the mould of FIG. 1,

[0086] FIG. 3 is a schematic view on a further enlarged scale of a portion of the mould of FIG. 2,

[0087] FIG. 4 is a schematic cross-sectional view of a portion of a mould for vulcanising tyres for vehicle wheels formed according to a second exemplary embodiment of the present invention,

[0088] FIG. 5 is a schematic view of the mould portion of FIG. 4 in a different operating configuration.

[0089] With initial reference to FIGS. 1 to 3, a first example of a mould for vulcanising tyres for vehicle wheels formed according to the present invention is denoted as a whole by 1.

[0090] The mould 1 has a conventional overall general structure and comprises a closed moulding chamber in which a green tyre 50 is received for the moulding and vulcanisation process.

[0091] The tyre 50 has a generally toroidal shape developed around a rotational axis and comprises a tyre structure that is conventional per se, on which an elastomeric tread band 101 is arranged in a radially outer position, on which tread band there is defined a tread surface intended for contact with a road surface, as well as a pair of sidewalls 52, extended from the ends of the tread surface towards the rotational axis.

[0092] With reference to the radial and axial directions of the tyre 50 when it is received in the mould 1, the moulding chamber is delimited radially by a plurality of heads 2, generally at least 8, which are suitably shaped to form annular sectors and which are substantially intended to contact the tread band 101, and axially by a pair of sidewall plates 3, which are substantially intended to contact the tyre sidewalls 52. Both the heads 2 and sidewall plates 3 may be moved away from each other to allow the mould to be opened and the green tyre to be inserted into the moulding chamber and removed once it has been moulded and vulcanised.

[0093] A heating device 7 is associated with the heads 2 and sidewall plates 3 to transmit to the green tyre the heat necessary to reach the temperature intended for vulcanisation.

[0094] Inside the moulding chamber of the mould 1, a membrane, which is conventional per se and not shown in the accompanying figures, may be provided and may be expanded to compress the green tyre 50 against the inner walls of the heads 2 and sidewall plates 3 at a predetermined pressure.

[0095] On the inner walls of the mould 1 intended to come into contact with the green tyre, corresponding pluralities of raised portions and recesses are suitably formed so as to obtain, by moulding on the radially outer surface of the tread band 101, the configuration of the tread pattern and, on the sidewalls 52, writing and images useful, for example, for providing visible information to the user regarding the characteristics of the tyre 50.

[0096] In particular, on at least one sidewall plate 3, and preferably on both sidewall plates 3, a moulding surface 4 is defined and is intended to contact the outer surface of a tyre sidewall 52.

[0097] On the moulding surface 4 of the sidewall plate 3 there is also provided, in a suitable position, a seat 5 to accommodate, with the possibility of removal, an insert 10.

[0098] The insert 10 comprises a main body 11, on which there is defined a base surface 12, turned towards the outside of the sidewall plate 3 when the insert 10 is received in the seat 5, as well as a rod 13 extended from the main body 11, from the opposite side to the base surface 12.

[0099] The rod 13 is preferably fixed to the main body 11 by means of a screw coupling, so that the rod can be recovered and reused when replacing the insert 10.

[0100] Preferably, from the main body 11 there also extends, in a position parallel to and spaced-apart from the rod 13, a plug 14 (shown in FIGS. 4 and 5) intended to be received in a corresponding recess formed inside the seat 5.

[0101] The shape of the seat 5 matches the shape of the main body 11, the rod 13 and the plug 14, so that the insert 10 can be inserted into the seat 5 with a specific, predefined orientation. In this way, an insertion direction X of the insert 10 into the seat 5, which is substantially parallel to the axis of the rod 13 and the plug 14, is identified.

[0102] Preferably, the main body 11 has a profile tapered away from the base surface 12, so as to allow a substantially tight fit with the sidewall plate 3, and so as to prevent, as far as possible, any elastomeric material from entering the seat 5.

[0103] On the rod 13, in a generally median position, there is defined a first shoulder 17 oriented so as to diverge away from the main body 11 and inclined with respect to the axis of the rod 13 by an angle of about 30°. In other words, the first shoulder 17 connects a portion of the rod 13 of smaller diameter to a portion of the rod of larger diameter, with the larger diameter portion being further away from the main body 11 than the portion of the rod of smaller diameter.

[0104] The first shoulder 17 is defined by a first flank of a circumferential groove 15 formed on the rod 13. The circumferential groove 15 has a generally trapezoidal section, with a bottom 16, connected to the outer surface of the rod 13 by the first shoulder 17 from the side facing a free end 13a of the rod 13 and, from the side facing the main body 11, by a second flank of the groove 18.

[0105] The second flank of the groove 18 is inclined with respect to the axis of the rod 13 by an angle of about 45°.

[0106] On the rod 13, in a position between the first shoulder 17 and the free end 13a there is also defined a second shoulder 19, which is oriented so as to diverge as it approaches the main body 11 (i.e. is oriented so as to converge towards the free end 13a), and is inclined with respect to the axis of the rod 13 by an angle of about 30°. In other words, the second shoulder 19 connects a portion of the rod 13 of smaller diameter to a portion of the rod of larger diameter, with the portion of larger diameter being closer to the main body 11 than the portion of the rod of smaller diameter.

[0107] As mentioned above, the base surface 12 faces the inside of the moulding chamber and is intended for contact with the tyre sidewall 52.

[0108] The coupling of the insert 10 in the seat 5 is such that the base surface 12 is substantially continuous with the moulding surface 4 of the sidewall plate 3, without appreciable steps in the transition between the two surfaces.

[0109] In addition, the base surface 12 has a curved profile, quite similar to the profile of the moulding surface 4, so as to maintain the continuity of the overall surface trend.

[0110] The base surface 12, seen from above, can have any desired shape, for example a generally rectangular shape with rounded corners.

[0111] Any desired information or logo, for example an alphanumeric lettering or QR code, can be formed on the base surface 12.

[0112] On the sidewall plate 3 there is also provided a retaining element 20 designed to retain the insert 10 in the seat 5 in a removable manner.

[0113] In the first exemplary embodiment described herein with particular reference to FIGS. 2 and 3, the retaining element 20 comprises three locking elements 21, mounted on the sidewall plate 3 and designed to contact the rod 13 of the insert 10 at the first shoulder 17.

[0114] In particular, each locking element 21 comprises a sphere 22, protruding into the seat 5 and fixed to the free end of a spring 23, which is in turn received and guided in a corresponding channel 24, formed in the sidewall plate 3 and open in the seat 5. In particular, each channel 24 is radially extended from the portion of the seat 5 in which the rod 13 is received, substantially perpendicularly to the insertion direction X, thus defining an operating direction Y in which the locking element 21 can be moved inside the seat 5.

[0115] The three locking elements 21 are arranged in a coplanar manner in the same radial plane with respect to the insertion direction X and spaced apart at equal angles of about 120°.

[0116] In addition, each channel 24 is formed in such a position that it is substantially aligned in the operating direction Y with the first shoulder 17 when the insert 10 is inserted in the seat 5.

[0117] In this way, when the insert 10 is inserted in the seat 5, the sphere 22, under the stress of the spring 23, is moved substantially inside the circumferential groove 15, defining a locking position of the locking element 21.

[0118] In this position, the sphere 22 is engaged in the circumferential groove 15 and retains the insert 10 in the seat 5.

[0119] In particular, when in the locked position, the outer surface of the sphere 22, which defines a first contact surface 22a, is abutted against the first shoulder 17 in such a way that, due to the inclination of the latter with respect to the insertion direction X and the operating direction Y, part of the force with which the sphere 22 is urged against the rod 13 assumes a direction parallel to the insertion direction X and directed towards the free end 13a of the rod. In this way, the locking element 21, when moved into the locking position, not only prevents the insert 10 from escaping from the seat 5, but actively retains it inside.

[0120] In the locking position, the sphere 22 does not abut the bottom 16 of the groove 15, and therefore the full force exerted by the spring 23 is applied to the first shoulder 17, and therefore the component of this force directed towards the free end 13a is as large as possible.

[0121] When the three locking elements 21, which are substantially identical to each other and are arranged in a coplanar manner, spaced apart at equal angles, are all moved into the locking position simultaneously abutting the first shoulder 17, the force exerted by them on the rod 13 perpendicular to the insertion direction X is substantially zero, while the force exerted by them on the rod 13 parallel to the insertion direction X is the sum of the individual components, increasing the force by which the insert is retained in the seat 5.

[0122] Each locking element 21 can also be moved in the operating direction Y from the locking position to a release position in which the sphere 22 is outside the circumferential groove 15 and the insert 10 can freely exit the seat 5.

[0123] To move the locking element 21 into the release position, the force of the spring 22 must be overcome.

[0124] For this purpose, in the preferred example described herein, it is provided that on the sidewall plate 3 there is formed a passage 25 which connects the seat 5 to the outside of the mould 1.

[0125] The passage 25 extends substantially perpendicular to the insertion direction X and is open in the seat 5 so that it is slightly spaced from the free end 13a of the rod 13, when the insert 10 is received in the seat 5.

[0126] In this way it is possible to insert a manoeuvring tool 26 into the passage 25, which manoeuvring tool is able to contact the rod 13 at its free end 13a and push it along the insertion direction and out of the seat 5. To facilitate this operation, the manoeuvring tool 26 preferably has a pointed or slanted end (as shown in FIG. 2).

[0127] The action of the manoeuvring tool 26 is sufficient to move the rod 13 outwards from the seat 5 by a sufficient amount so that the sphere 22 exits the circumferential groove 15 and abuts the second shoulder 19. In this position, due to the inclination of the second shoulder 19, part of the force exerted by the spring 22 is transformed into a component directed along the axis of the rod 13 towards the main body 11, so that the insert 10 is pushed out of the seat 5.

[0128] FIGS. 4 and 5 show a second exemplary embodiment of a mould for vulcanising and moulding according to the present invention, denoted as a whole by 100, in which components similar to those in the previous example are denoted by the same reference numeral.

[0129] The mould 100 differs from the mould 1 in that the insert 10 is retained inside the seat and removed from it in a different way.

[0130] The insert 10 comprises a main body 111 similar to the main body 11, and a rod 113 extending from the main body 111 from the opposite side to the base surface 12.

[0131] The free end of the rod 113 is shaped like a fork and comprises a pair of tines 113a between which there is pivoted a wheel 101, freely rotating about its axis, perpendicular to the rod 113. The wheel 101 represents a hooking element of the insert 10, which can be engaged by a locking element 121 designed to retain and remove the insert 10 in/from the seat 5, as better explained below.

[0132] The locking element 121 can be moved in an operating direction Y defined by the axis of a channel 124 between a locking position, in which the locking element 121 engages and retains the insert 10 in the seat 5, and a release position, in which the locking element 121 is disengaged from the insert 10, which can then be removed from the seat 5.

[0133] The locking element 121 is urged towards the locking position by a spring 123 which extends in the channel 124.

[0134] The channel 124 is formed in the sidewall plate 3 substantially perpendicularly to the insertion direction X and is open at one end thereof in the seat 5 and at one longitudinally opposite end thereof outside of the mould 100.

[0135] Preferably, the channel 124 is open in the seat 5 at the free end of the rod 113 when the insert 10 is engaged in the seat 5.

[0136] On the locking element 121 there is formed a slot 102, with a profile open to the outside of the locking element, which is designed to engage the wheel 101 of the rod 113 when the insert 10 is inserted in the seat 5.

[0137] In particular, the slot 102 is delimited by a first contact surface 103 and by a second contact surface 104 joined together at the bottom of the slot 102.

[0138] The first contact surface 103 and the second contact surface 104 are substantially parallel to each other and are inclined with respect to the operating direction Y by an angle of about 30°.

[0139] The locking element 121 also comprises a pin 105 which extends inside the channel 124 from the side opposite to the seat 5, through the spring 123, until it protrudes outside the sidewall plate 3.

[0140] The portion of the pin 105 protruding from the channel 104 outside the mould is suitably threaded so that it can be engaged by screwing by a manoeuvring tool 106.

[0141] This instrument comprises an internal threaded cavity, open at one axial end 107 of the manoeuvring instrument 106.

[0142] As the tool is screwed onto the threaded pin 105, the axial end 107 of the manoeuvring tool 106 contacts a fixed end flange 108 of the channel 124, causing the locking element 121 to move in the operating direction Y towards the release position, in contrast to the action of the spring 123.

[0143] During this movement, the wheel 101 of the rod 113 is contacted by the second contact surface 104, which, due to its inclination, pushes the rod 113 along the insertion direction X, out of the seat 5.

[0144] On the contrary, by unscrewing the manoeuvring tool 106, the locking element 121 is released and moved into the locking position by the action of the spring 123.

[0145] During this displacement, the wheel 101 of the rod 113 is contacted by the first contact surface 103, which is wedged between the tines 113a above the wheel 101 (as shown in FIG. 4), and, due to its inclined shape, pulls the rod 113 in the insertion direction X inside the seat 5.