TYRE MOLDING PRESS

Abstract: A tyre molding press having a fixed bed and a cross-­ piece, which crosspiece is designed to travel, by virtue of a crank mechanism, along vertical guides formed partly along the uprights and partly along extensions of the same; the guide portions extending along the upright extensions enabling extra vertical travel of the crosspiece, and each being limited at the rear by a switch element which may be operated selectively for opening the respective guide at the rear and enabling the big end of the respective connecting rod to slide backwards, with the crank fixed, and along an end surface of the respective upright, in such a manner as to tilt back the crosspiece.

Description: The present invention relates to a tyre molding press according to the preamble of claim 1. For molding and curing green tyres, presses are known from the teachings of GB-A-1 157 140 to be employed comprising a fixed bed designed to receive, on top, at least a bottom mold for a green tyre, and having two substantially vertical, lateral uprights, on each of which there is formed a substantially vertical slot open at the top. The said two slots define the slideways of a crossbar constituting a common slide for two crank mechanisms, each connected to one of the said uprights. The connecting rod of each of the said crank mechanisms is of such a length that the said slide moves over the top end of the said slots when the connecting rods reach the top dead centre position. The said slide supports, in rotary manner, a crosspiece located between the said two uprights and fitted with at least a top mold for a green tyre. The said crosspiece is connected integral with two appendixes, the free end of each of which engages a substantially vertical guide formed on a respective upright and arranged in such a manner that its top end is reached by its respective appendix after the said slide reaches the top end of the respective said guides, and before the connecting rods of the said two crank mechanisms reach the top dead centre position. Clearly, therefore, when the crosspiece on the press is pushed up by the two crank mechanisms for opening the mold, the crosspiece is moved upwards until the said two appendixes reach the top end of the respective guides. Further rotation of the cranks, beyond this point, causes the slide to slide backwards along supports formed on top of the uprights, and, at the same time, tilts the crosspiece back about the slide axis. As a result, the mold on the crosspiece turns upwards, thus enabling full access for removing the molded tyre. Such backward tilting of the crosspiece occurs as soon as the slide moves over the top of the uprights, and is caused by the tiltback torque produced by the combined effect of the slide sliding backwards by gravity along the said supports formed on top of the uprights, and the said appendixes on the crosspiece engaging inside the respective guides. Though widely used for molding tyres, presses of the aforementioned type involve a number of both functional and structural drawbacks. Tilting back the crosspiece on the press for enabling access to and removing the molded tyre/s is not only a relatively time-consuming operation, which consequently slows down production, but also subjects the press itself to tiltback moments directly proportional to the weight of the molds involved. These moments, which are caused by rearward displacement of the centre of gravity of the crosspiece in relation to the bed, are grounded through the bolts anchoring the bed to the floor, with the result that the bolts must be continually inspected and have a relatively short working life. The aim and object of the present invention is to provide a tyre molding press involving none of the aforementioned drawbacks. This aim and object is solved according to the present invention by a tyre molding press as described in claim 1. According to a preferred embodiment of the invention as described above, the said crosspiece is connected, in rotary manner, to the said slide, in such a manner as to turn, in relation to the slide itself, about a substantially horizontal axis; securing means being provided for angularly securing the said crosspiece to the said slide during displacement of the said slide along the said first and second guide portions. The said securing means preferably comprise third substantially vertical guide means, and slide means mounted so as to slide along the said third guide means and connected integral with the said crosspiece; the said first and the said third guide means being of substantially the same length and offset in height. One embodiment of the present invention will be described by way of a non-limiting example, with reference to the accompanying drawings, in which : Fig.1 shows a view in perspective of a preferred embodiment of the press according to the teachings of the present invention; Fig.s 2, 3 and 4 short side views of the Fig.1 press in three distinct operating positions. Number 1 in Fig.1 indicates a tyre molding and curing press comprising a substantially parallelepiped bed 2 from the opposite side ends of which there extend upwards two uprights 3. On the outside of each upright 3, bed 2 supports, in rotary manner, a circular crank 4 fitted onto a centre shaft (not shown). The said shaft is arranged substantialy horizontally inside bed 2, in such a manner as to connect the said two cranks 4, and is connected to an output member (not shown) of a reduction device 5 driven by an output shaft 6 on motor 7. Cranks 4 form part of a crank mechanism indicated as a whole by 8 and comprising, for each crank 4, a connecting rod 9 the small end of which is hinged onto a crankpin defined by a substantially horizontal, eccentric pin 10 on respective crank 4, and the free end of which is fitted with a slide 11 consisting of a substantially horizontal shaft connecting the said two connecting rods 9. Press 1 also comprises a crosspiece 12 mounted for rotation on slide 11 and supporting two top molds 13, the respective bottom molds 14 of which are fixed on bed 2. According to an obvious variation (not shown), slide 11 consists of two coaxial pins connected, in rotary manner, to the top end of respective connecting rods 9 and integral with the opposite lateral ends of crosspiece 12. When moved to and from bed 2 by crank mechanism 8, slide 11 is guided by substantially vertical slots 15 engaged by respective cylindrical bushings integral with slide 11 and each defining a sliding shoe 16. Each slot 15 comprises a lower portion 18 formed along respective upright 3, and an upper portion 19 extending along an extension or appendix 20 extending substantially vertically from the top of the said upright 3. As shown, particularly in Fig.s 2 and 4, each appendix 20 is substantially in the form of an upside-down "U" and comprises a horizontal top plate 21, from which there extend downwards a substantially vertical front arm 22 connected integral with the top of respective upright 3, and a rear arm 23 hinged, at its top end, to a substantially horizontal pin 24 on plate 21. To the top of arm 23, there is connected an appendix 25, to the free end of which is hinged the free end of a rod 26 of an air-powered jack 27, the body 28 of which is supported on plate 21. Arm 23 constitutes a switch member which, when set in a normal first operating position substantially parallel with arm 22, defines, with arm 22, the said upper portion 19 of respective slot 15. When, on the other hand, subsequent to operation of air-powered jack 27, arm 23 is turned about the axis of pin 24 towards arm 22, the arched rear side edge 29 of arm 23 moves into a position substantially tangent with the rear side edge of arm 22. In this position, arm 23 defines an opening 30, passing through which respective shoe 16 may abandon the said lower portion 18 of respective slot 15 and move over the top of respective upright 3 in sliding contact with a curved surface 31 defining the top end of respective upright 3 and extending substantially transversely in relation to the axis of slot 15. As shown, particularly in, Fig.s 2 and 3, crosspiece 12 presents an angle control device 32 designed to control the angle of crosspiece 12 in relation to slide 11. Device 32 comprises two downward-sloping arms 33 extending rearwards from a rear surface of crosspiece 12 and each fitted, on its free end, with a respective horizontal pin 34. Each pin 34 engages, in rotary and transversely-sliding manner, a respective slot 35 formed along respective upright 3, parallel with respective slot 15, and of substantially the same length as slot 15. Each slot 35 on respective upright 3 is offset downwards in relation to respective slot 15, so that, when slide 11 occupies the lower end of slots 15, pins 34 occupy the lower ends of respective slots 35. As shown, particularly in Fig.s 2, 3 and 4, to the front of each bottom mold 14, bed 2 supports a device 36 for supporting an unmolded tyre (not shown) and designed to cooperate with a known type of automatic device 37 for feeding the said tyre onto the said bottom mold 14. Operation of press 1 will now be described starting from the closed molding position shown in Fig.2. Starting from the said closed molding position, press 1, after allowing sufficient time for molding and curing the tyres, is opened for enabling the finished tyres to be unloaded. For this purpose, motor 7 is operated for turning cranks 4 and pushing up crosspiece 12 and top molds 13 connected to it. Unlike known presses, on which the required clearance between top molds 13 and bottom molds 14 for removing the finished tyres is achieved by raising and subsequently tilting up and back crosspiece 12 and top molds 13 connected to it, on press 1, the said clearance is achieved by maintaining arm 23 in the normal closed position shown in Fig.s 2 and 3, and by moving connecting rods 9 into the top dead centre position. During such displacement of connecting rods 9, slide 11 not only slides along the entire lower portion of slots 15, but also travels in extra vertical distance along the entire upper portion 19 of slots 15. At the sane time, pins 34 of control device 32 shift from the lower end to substantially the upper end of respective slots 35, thus maintaining crosspiece 12 at a fixed angle in relation to slide 11. The increased clearance between top and bottom molds 13 and 14 provided, on press 1, by the extra travel of slide 11 along upper portions 19 of slots 15 enables the finished tyres to be unloaded and further tyres to be loaded with no need for tilting back crosspiece 12 and top molds 13 connected to it. As a result, tyres may be loaded and unloaded relatively quickly, and with no undue strain being exerted on the fasteners securing bed 2 to the floor. The same does not apply, however, if the molds are to be changed after unloading the finished tyres. In fact, changing top molds 13 would prove fairly difficult with crosspiece 12 in the non-tilted position shown in Fig.3. For changing the molds, therefore, arm 23 is moved by jack 27 into the open position shown in Fig.4, prior to raising crosspiece 12 by means of crank mechanism 8. By so doing, slide 11 reaches openings 30 as pins 10 approach the top dead centre position. Further rotation of cranks 4 causes shoes 16 to move through respective openings 30, and then both shoes 16 and slide 11 to slide by gravity along surfaces 31. Shoes 16 continue sliding until, as shown in Fig.4, connecting rods 9 exceed top dead centre and line up with the rotation centres of respective cranks 4. As shoes 16 slide along respective supporting surfaces 31, crosspiece 12 moves backwards towards slots 35. As a result, pins 34 are forced to slide down inside respective slots 35, thus causing crosspiece 12 and top molds 13 connected to it to turn upwards about the axis of slide 11. As shown in Fig.4, when shoes 16 come to the end of their travel along supporting surfaces 31, top molds 13 are tilted roughly 90° in relation to their original vertical position, thus enabling them to be changed easily. In other words, therefore, the switch member consisting of mobile rear arm 23 on appendix 20 provides, when set to the open position, for operating press 1 in the same way as a known press, but only for changing the molds. For normal molding operation, on the other hand, arm 23 is set in the vertical closed position, and not only prevents crosspiece 12 and top molds 13 connected to it from being tilted back, but also enables crosspiece 12 to travel an extra vertical distance in an extremely short space of time, thus enabling troublefree unloading of the finished tyres, without introducing tiltback moments resulting in anomalous strain on the fasteners securing bed 2 to the floor.

Claims: A tyre molding press (1) comprising a fixed bed (2); two uprights (3) extending upwards from the said bed (2); a crosspiece (12) movably mounted between said uprights (3); and a crank mechanism (8) for driving the said crosspiece (12) to and from the said bed (2), the said crank mechanism (8) comprising a slide (11) connected to the said crosspiece (12), and first vertical guide means (15), for the said slide (11), extending upwards from the said bed (2); characterised by the fact that each said upright (3) presents, at the top end, an upper surface (31) constituting second horizontal guide means for the said slide (11), and a vertical extension (20); the said first guide means (15) comprising a first guide portion (18) extending along each said upright (3), and a second guide portion (19) extending along each said extension (20); and a rear arm (23) constituting a switch means being provided for placing each said first guide portion (18) selectively in communication with the respective said second guide portion (19) and with the said second guide means. A tyre molding press (1) as claimed in Claim 1, characterised by the fact that the said crosspiece (12) is rotatably connected to the said slide (11) so as to turn about the axis of the same; angle control means (32) being provided for angularly securing the said crosspiece (12) in relation to the said axis during displacement of the said slide (11) along the said first and the said second guide portion (18,19). A tyre molding press (1) as claimed in Claim 2, characterised by the fact that the said angle control means (32) comprise third vertical guide means (35), and slide means (39), said third guide means (35) movably retained within and connected integral with the said crosspiece (12); the said first (15) and the said third guide means (35) being of substantially the same length and offset in height. A tyre molding press (1) as claimed in Claim 3, characterised by the fact that the said first (15) and the said third guide means (35) respectively comprise a first (15) and a second slot (35) formed on each said upright (3) and extending vertically; each said first slot (15) extending along the respective said upright (3) and along the respective said extension.(20). A tyre molding press (1) as claimed in Claim 4, characterised by the fact that each said second slot (35) is offset downwards in relation to the respective said first slot (15); the said angle control means (32) comprising two arms (33) integral with the said crosspiece (12) and extending downwards from the same; and each said arm (33) presenting a transverse pin (34) engaged, in rotary and transversely-sliding manner, inside a respective said second slot.(35). A tyre molding press (1) as claimed in any one of the foregoing Claims, characterised by the fact that the said extension (20) of each said upright (3) is substantially in the form of an upside-down "U", and comprises a fixed front arm (22) and the rear arm (23) designed to turn about its top end; the said rear arm (23) actuating means (26,27,28) being provided for moving the said rear arm (23) between a normal vertical closed position parallel with the respective said front arm (22), and an open position wherein the said rear arm (23) defines, in the respective said extension (20), a lateral opening (30) enabling communications between the upper end of the respective said lower portion (18) of the said first vertical guide means (15) and the said upper surface (31) constituting the said second guide means; the width of said lateral opening (30) enabling passage of the said slide (11). A tyre molding press (1) as claimed in Claim 6, characterised by the fact that the said slide (11) being provided with shoes (16) for enabling it to slide on the said upper surfaces (31).

Inventors: MAURO, ROBERTO
Applicants: THE FIRESTONE TIRE & RUBBER COMPANY
Application year: 1987
Main classification: B29D30
IPC codes: B29D30, B29L30, B29K105, B29C33, B29K21, B29C43