Tire curing unit

Abstract: A curing unit (1)(40) wherein a mold (2) is defined by a first and second releasable half mold (3,4) moving in relation to each other along a first axis (6); the first half mold (3) being designed to turn about a second axis (30) perpendicular to the first axis (6) by virtue of actuators (31) which, when the half molds (3,4) are released, turn the first half mold (3) to and from a maintenance position wherein its concave side faces upwards.

Description: The present invention relates to a tire curing unit. In particular, the present invention relates to a curing unit comprising a segmented mold in turn comprising two oppositely-concave half molds coaxial with each other and with a first vertical axis; a number of mold segments connected in sliding manner to a first of said half molds, said first half mold being an upper half mold, and a second of said half molds being a lower half mold; means for releasably connecting said half molds; and first actuating means for moving said half molds in relation to each other along said first axis and between a closed and open position. On known curing units of the aforementioned type, for removing and replacing the mold segments with others of a different design and/or size, the half molds are opened for enabling access to the segments by one or more operators. In general, the above procedure is a painstaking, time-consuming job usually requiring the assistance of more than one operator. This is due to the fact that the space available between the half molds is, in general, very limited, and that the segments, being coupled to the upper half mold, are to be lifted and held in position before being coupled to the upper half mold itself. It is an object of the present invention to provide a curing unit designed to overcome the aforementioned drawback. According to the present invention, there is provided a tire curing unit comprising a segmented mold in turn comprising two oppositely-concave half molds coaxial with each other and with a first vertical axis; a number of mold segments connected in sliding manner to a first of said half molds, said first half mold being an upper half mold, and a second of said half molds being a lower half mold; means for releasably connecting said half molds; and first actuating means for moving said half molds in relation to each other along said first axis and between a closed and open position; characterised by the fact that second actuating means are provided for rotating at least said first half mold about a second axis and to and from a maintenance position wherein the concave side of said first half mold faces substantially upwards; the first actuating means being located between said half molds, and the second actuating means being located between said first actuating means and said first half mold. A number of non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which: Fig.1 shows a view in perspective of a first embodiment of the curing unit according to the present invention; Fig.2 shows a view in perspective of the Fig.1 unit in a different operating position; Fig.3 shows a view in perspective of a second embodiment of the curing unit according to the present invention. Number 1 in Fig.1 indicates a tire curing unit comprising a segmented mold 2 defined by releasable, substantially cup-shaped upper and lower half molds 3 and 4 arranged, when operative, with their concave sides facing one another. Lower half mold 4 Comprises a cylindrical wall 5 having a vertical axis 6 and closed at the bottom by end wall 7. Cylindrical wall 5 presents a flange 8 extending radially outwards from the top edge of wall 5; and two diametrically-opposed radial appendixes 9, indicated respectively 9a and 9b, integral with and extending outwards from the outer surface of wall 5. Each appendix 9 rests on a respective stand 10 which, together with the other stand 10, supports mold 2 and provides for maintaining lower half mold 4 a given height off the floor. End wall 7 is fitted through in sliding manner with a known heat exchange unit 11 extending beneath lower mold 4, coaxially with axis 6, and moved axially in relation to lower mold 4 between a raised operating position and a lowered idle position by means of a lifting device 12. A detailed description of unit 11 is provided in USA Patent n.4,747,765, to which full reference is made herein in the interest of full disclosure. Upper half mold 3 comprises a cylindrical wall 13 coaxial with vertical axis 6 and closed at the top by end wall 14. Cylindrical wall 13 presents a flange 15 extending radially outwards from the bottom edge of wall 13 and having a number of equally-spaced through slots 16. Flange 8 presents a number of equally-spaced through holes 17 aligned with respective slots 16 for assembling, on to flange 8, a known clamping device 18 comprising a number of actuators 19 connected integral with the lower surface of flange 8 at respective holes 17. Each actuator 19 comprises an output rod 20 extending through a respective hole 17, parallel to axis 6, and fitted on its free end with an elongated transverse plate 21. Together with respective rod 20, each plate 21 slides, parallel to axis 6, through a respective slot 16, and is turned about the axis of rod 20 by respective actuator 19, so as to engage the upper surface of flange 15 and grip flanges 15 and 8 in fluidtight manner when rod 20 moves down. Appendixes 9a, 9b of lower half mold 4 are fitted through with respective bushes 22 parallel to axis 6 and engaged in sliding manner by respective guide rods 23, 24 located between respective appendixes 9a, 9b and respective appendixes 25, indicated respectively 25a and 25b, extending radially outwards from wall 13 of half mold 3 and facing respective appendixes 9a, 9b. Rods 23, 24 are fitted on the top end with respective brackets 26, 27 for connecting rods 23, 24 to the fixed outer portion of respective supports 28,29, the rotary inner portions (not shown) of which are fitted on to respective pins (not shown) integral with respective appendixes 25a, 25b and coaxial with each other and with a horizontal axis 30 intersecting axis 6. The pin integral with appendix 25a forms an extension of the output shaft (not shown) of a reversible electric motor 31 supported on bracket 26. Two linear actuators 32 and 33 provide for axially displacing upper half mold 3 in relation to lower half mold 4, in the angular position defined by rods 23, 24 and respective bushes 22, and between a lowered operating position (not shown) and the raised idle position shown in Fig.1. Each actuator 32 and 33 comprises a body 34 connected integral with respective appendix 9a, 9b; and an output rod 35 extending parallel to axis 6 and at least equal in length to the outside radius of flange 15. The top end of rod 35 of actuator 32 is hinged to the lower surface of bracket 26, while the top end of rod 35 of actuator 33 is hinged to the fixed portion of support 29 via the interposition of a bracket 36. As shown in Fig.2, upper half mold 3 houses a number of known mold segments 37 connected in sliding manner to the conical inner surface (not shown) of a known supporting ring 38, the cylindrical outer surface of which is made integral with the inner surface of cylindrical wall 13. Being perfectly standard, no explanation is required herein of the procedure whereby the green tire (not shown) is assembled inside mold 2 with half mold 3 in the raised idle position; mold 2 is closed; the green tire is cured and mold 2 opened for extracting the cured tire. On curing unit 1 as described above, however, for maintaining and/or changing mold segments 37, upper half mold 3, when raised by actuators 32 and 33, may be set to a maintenance position with its concave side facing upwards. The maintenance position of upper half mold 3 as shown in Fig.2 not only relieves the operator of the necessity for working between half molds 3 and 4, but also enables mold segments 37 to be detached safely from ring 38 with no danger to the operator. In fact, in the maintenance position, upper half mold 3 functions as a container for segments 37. By virtue of the vertical axis 6 of unit 1 as described above, half mold 3 is switched from the Fig.1 idle position to the Fig.2 maintenance position by simply turning it upside down so that the concave sides of half molds 3 and 4 both face upwards, and half molds 3 and 4 are again coaxial with each other and axis 6. This is done by activating motor 31, which provides for rotating upper half mold 3 by 180° about axis 30. If, according to a variation not shown, axis 6 is other than vertical, said maintenance position, wherein half mold 3 is arranged with its concave side facing upwards, is achieved by rotating half mold 3 about axis 30 by an angle of other than 180°. The Fig.3 embodiment relates to a curing unit 40 differing in a number of respects from unit 1, and having an upper and lower half mold 3 and 4 designed to move, coaxially with vertical axis 6, along two vertical pillars 41 mounted on a base 42. On the free end of each appendix 9, lower half mold 4 is fitted integral with a slide 43 engaging in sliding manner a respective pillar 41. Similarly, upper half mold 3 presents a slide 44 fitted integral with the fixed portion of each support 28, 29 and engaging in sliding manner a respective pillar 41. Like bracket 26 on unit 1, slide 44 connected to support 28 supports motor 31 for rotating upper half mold 3, in relation to pillars 41 and about axis 30, between the idle position shown in Fig.3 and a maintenance position (not shown) wherein the concave side of half mold 3 faces upwards. Half molds 3 and 4 are moved in opposite directions between the operating position (not shown), wherein mold 2 is closed and half molds 3 and 4 are gripped in fluidtight manner by clamping device 18, and the Fig.3 idle position, wherein mold 2 is open, by means of an actuating device 45 comprising a reversible electric motor 46 on the bottom end of each pillar 41. By means of a joint 47, each motor 46 provides for rotating a vertical shaft 48 having two oppositely-threaded portions 49 and 50 connected to respective appendixes 9 and 25 via respective screw-nut screw couplings 51 and 52. For each pillar 41, actuating device 45 also comprises a cable 53 wound about a pulley 54 on the free end of pillar 41, for connecting a respective slide 43 of lower mold 4 to a respective slide 44 of upper mold 3. The design of actuating device 45 enables lower half mold 4 to act as a counterweight for upper half mold 3 during displacement of the same between said operating and idle positions, and also enables half molds 3 and 4 to be displaced using relatively low-power motors 46 required to overcome substantially only the internal friction of unit 40.

Claims: A tire curing unit (1)(40) comprising a segmented mold (2) in turn comprising two oppositely-concave half molds (3,4) coaxial with each other and with a first vertical axis (6); a number of mold segments (37) connected in sliding manner to a first (3) of said half molds (3,4), said first half mold (3) being an upper half mold, and a second (4) of said half molds (3, 4) being a lower half mold; means (18) for releasably connecting said half molds (3,4); and first actuating means (32,33) (45) for moving said half molds (3,4) in relation to each other along said first axis (6) and between a closed and open position; characterised by the fact that second actuating means (31) are provided for rotating at least said first half mold (3) about a second axis (30) and to and from a maintenance position wherein the concave side of said first half mold (3) faces substantially upwards; the first actuating means (32, 33) being located between said half molds (3,4), and the second actuating means (31) being located between said first actuating means (32) and said first half mold (3). A curing unit as claimed in Claim 2, characterised by the fact that, when said first half mold (3) is in said maintenance position, said half molds (3,4) are coaxial with each other. A curing unit as claimed in Claim 1 or 2, characterised by the fact that said second axis (30) is a horizontal axis intersecting said first axis (6). A curing unit as claimed in any one of the preceding Claims, characterised by the fact that said lower half mold (4) is axially fixed; said first actuating means (32,33) being mounted for axially displacing said upper half mold (3) in relation to said lower half mold (4) between said open and closed positions. A curing unit as claimed in any one of the preceding Claims, characterised by the fact that it also comprises guide means (41) extending parallel to said first axis (6); and first (44) and second (43) slide means mounted so as to slide along said guide means (41); both said half molds (3,4) traveling axially in opposite directions between said open and closed positions; and each said half mold (3)(4) being connected to a respective said slide means (44)(43) and traveling with the same along said guide means (41). A curing unit as claimed in Claim 5, characterised by the fact that said first actuating means (45) are located between said two slide means (44,43); said second actuating means (31) being located between said first half mold (3) and said respective slide means (44). A curing unit as claimed in Claim 5 or 6, characterised by the fact that said first actuating means comprise flexible connecting means (53) between said half molds (3,4), and transmission means (54) for said flexible connecting means (53); said transmission means (54) being located on said upper half mold (3). A curing unit as claimed in Claim 7, characterised by the fact that said transmission means (54) are supported on said guide means (41).

Inventors: SIEGENTHALER KARL J, SIEGENTHALER, KARL J.
Applicants: BRIDGESTONE CORP, BRIDGESTONE CORPORATION
Application year: 1992
Main classification: B29D30
IPC codes: B29C35, B29K105, B29C33, B29K21, B29D30, B29L30