AUTOMATIC TRANSVERSE SPLICING DEVICE FOR ASSEMBLING TIRES

Abstract: For assembling tires on a tire building drum, the two opposite ends of at least some of the successive superimposed layers of elastomeric material constituting the tire are secured to the drum and spliced together by means of an automatic splicing device, a concave-surface roller of which is moved parallel with the axis of the tire building drum, by virtue of a driving device, and into contact with the outer surface of the tire building drum, by virtue of an actuating device.

Description: The present invention relates to an automatic transverse splicing device for assembling tires. For manufacturing tires, in particular carcasses of first stage tires, a tire building drum is known to be employed; onto which drum are supplied successive layers comprising, for example, a first layer consisting of an innerliner preassembled, along each lateral edge, onto an abrasion strip and an outer strip constituting a sidewall on the tire, and a second layer consisting of a body ply. Presently, each of the said layers is generally fed onto the periphery of the tire building drum by means of a feeding device, which usually provides for cutting the layer into portions substantially equal in length to the circumferential development of the tire building drum. The front edge of a portion of the said first layer is first placed by the operator onto the outer surface of the tire building drum and pressed so as to adhere to the same. Subsequent rotation of the tire building drum causes the said first layer portion to be wound onto the drum, which is then followed by supply of a portion of the next layer. The latter portion is wound onto the tire building drum so as to form a cylinder, and its opposite end edges spliced by means of mechanical pressure of stitching. Similar mechanical pressure is applied through the second layer, for splicing together the opposite end edges of the said first layer. In the past, affixing the front axial edge of the first layer to the outer surface of the tire building drum and splicing together the opposite end edges of each layer were performed manually, and involved relatively long holdups during the tire manufacturing cycle. As, during such holdups, no additional operating and/or control functions could be performed by the splicing operators, this means a considerable amount of downtime was also involved. In connection with the above, it is to be pointed out that all the above splicing or stitching operations were performed manually notwithstanding the fact that an automatic splicing device was known from U.S. Patent No. 2,500,273, comprising a motorized carriage provided with stitching rollers, and mounted to reciprocate in an axial direction in relation to a tire carcass support. In the above carriage, elastic means were interposed between the stitching rollers and a frame of the carriage itself to apply a constant pressure to the material to be stitched; and the rollers were substantially cylindrical to press the material to be stitched on to the aforementioned carcass support, which consisted in an anvil having a flat surface for cooperation with the above stitching rollers. The above automatic splicing device was of no use when building a tire on a building drum first because the above cylindrical stitching rollers could perform substantially no stitching action when moving axially along a cylindrical surface; and second because, on a forming drum, tubular elements of substantially constant thickness are to be obtained when stitching, and such result could not be obtained by using elastically operated rollers such as those disclosed in the above U.S. patent. These rollers may be, in fact, used to stitch a tread on to a formed carcass on an anvil, but never to form a carcass on a tire building drum. It is an object of the present invention to provide a device enabling straightforward, low-cost automation for affixing the front axial edge of a first layer to the outer surface of a tire building drum, and for splicing together the opposite axial edges of the said first layer and the following layers. According to the present invention, there is provided an automatic transverse splicing device for assembling tires, the device being designed to cooperate with an outer lateral surface of a tire building drum, and comprising a splicing roller located facing said outer lateral surface of the tire building drum; guide means extending laterally in relation to, and parallel with, the axis of the tire building drum; slide means designed to travel along said guide means; and driving means for moving the slide means in reciprocating manner along the guide means; the splicing roller being supported by the slide means, and thrust means being provided between the slide means and the splicing roller, for moving the splicing roller, in relation to the slide means, towards an operating position contacting the outer surface of the tire building drum, characterized in that said thrust means are actuating means for positively moving the splicing roller to and from said operating position; said splicing roller consisting of a number of parallel rollers having different outside diameters, and combining to form a single roller, the outer surface of which is concave. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Fig. 1 shows a side view of one embodiment of the splicing device according to the present invention; Fig. 2 shows a partially-sectioned top view of the Fig. 1 device; and Fig. 3 shows an end view of the device in Fig.s 1 and 2. Numeral 1 in Fig. 1 indicates a tire building drum, in particular, a drum for building first stage tires or carcasses. As shown in Figs. 1 and 3, there is located substantially over drum 1 an automatic transverse splicing device 2 comprising a tubular, substantially square-section crosspiece 3 extending parallel with the axis of drum 1. Crosspiece 3 is supported in the position shown by a fixed support (not shown), and is provided at each axial end with a vertical bracket 4 supporting, in a rotary manner via the interposition of a respective bearing 5 (Fig. 2), a respective end of a screw 6. By means of a key 7, an end portion of screw 6 is fitted with a toothed pulley 8 driven, via a toothed belt 9, by a toothed pulley 10 fitted onto shaft 11 of electric motor 12 supported on crosspiece 3 by means of bracket 13. As shown, particularly in Fig. 2, screw 6 is connected to a nut screw 14 having an end flange 15 connected, via screws 16, to a first arm 17 of an L-shaped bracket 18, the second arm 19 of which extends parallel with crosspiece 3 and is connected, via screws 20, to carriage 21. Carriage 21 comprises a flat plate 22, arranged substantially vertically and connected to arm 19 via said screws 20, and two pairs of rollers 23, each of which is mounted for rotation on a pin 24 mounted through plate 22 and secured to the same by means of a respective nut 25. Each roller 23 includes an intermediate annular groove 26, and the rollers of each pair of rollers 23 are arranged on opposite sides of a blade 27 lying in a plane parallel with plate 22 and extending along substantially the entire length of crosspiece 3 to which blade 27 is connected integrally via the interposition of a spacer 28 (Figs. 2 and 3). Blade 27 presents tapered opposite side edges 29, designed to engage grooves 26 on rollers 23, and constitutes a fixed guide enabling the travel of carriage 21. As shown in Figs. 1 and 2, one end of carriage 21 is connected, via screw 30, to an appendix member 31, to the free end of which is hinged, via pin 32, a rocker arm 33. As shown in Figs. 2 and 3, rocker arm 33 consists of two substantially triangular plates 34 arranged facing each other and connected mutually integrally by means of a cylindrical spacer 35 perpendicular to plates 34 and crosspiece 3, and arranged substantially horizontally parallel with the rotational ax of rollers 23. Plates 34 are fitted through with pin 32 on one tip, and with additional pins 36 and 37 on the other two tips. Pin 36 provides for hinging rocker arm 33 to a fork 38 mounted on the free end of a rod 39 on an actuator 40, the end opposite that supporting rod 39 being hinged to carriage 21 via a threaded pin 41. Pin 37 is arranged parallel with pins 24, 32 and 36 and perpendicular to the rotational axis of tire building drum, and supports, in a rotary manner, via the interposition of respective bearings 42, a number of parallel rollers 43 having different diameters and combining to define a single splicing roller 44, the outer surface of which is concave and, as shown in Fig. 3, presents a curve radius equal to that of drum 1. In actual operation, a splicing roller 44 may be moved, by virtue of actuator 40, between a raised idle position, shown by the continuous line in Figs. 1 and 3, and a lowered operating position shown by the dotted line in Figs. 1 and 3 wherein the outer surface of splicing roller 44 contacts the outer surface of tire building drum 1. With roller 44 in the said lowered operating position contacting an end portion of drum 1, operation of motor 12 causes carriage 21 to travel along guide blade 27 and, at the same time, shifts roller 44 along the generating line of drum 1. The contact pressure between roller 44 and drum 1 may easily be regulated by means of actuator 40. When roller 44 comes to the end of its travel along drum 1, actuator 40 may be activated for returning roller 44 to its raised idle position before motor 12 is reversed for returning carriage 21 to its original position. From the foregoing description, it follows that roller 44 may be employed for fully automatically exerting controlled pressure along an axial portion of drum 1, which pressure may be employed for affixing directly onto the surface of drum 1 one end of a first layer of uncured or green elastomeric material (not shown), as well as for splicing together in a superimposed manner the front and rear edges of any layer of green elastomeric material (not shown). In connection with roller 44, it should be pointed out that forming the same from a number of parallel rollers 43 minimizes the rolling friction between roller 44 and drum 1, provides for substantially uniform contact pressure between roller 44 and drum 1, and substantially eliminates any danger of seizing.

Claims: An automatic transverse splicing device (2) for assembling tires, the device (2) being designed to cooperate with an outer lateral surface of a tire building drum (1), and comprising a splicing roller (44) located facing said outer lateral surface of the tire building drum (1); guide means (27) extending laterally in relation to, and parallel with, the axis of the tire building drum (1); slide means (21) designed to travel along said guide means (27); and driving means (12,9,6,14) for moving the slide means (21) in reciprocating manner along the guide means (27); the splicing roller (44) being supported by the slide means (21), and thrust means (33,40) being provided between the slide means (21) and the splicing roller (44), for moving the splicing roller (44), in relation to the slide means (21), towards an operating position contacting the outer surface of the tire building drum (1), characterized in that said thrust means (33,40) are actuating means (33,40) for positively moving the splicing roller (44) to and from said operating position; said splicing roller (44) consisting of a number of parallel rollers (43) having different outside diameters, and combining to form a single roller (44), the outer surface of which is concave. A device as claimed in Claim 1, characterized in that the concave outer surface of said parallel rollers (43) presents a curve radius that is substantially equal to the curve radius of the tire building drum (1). A device as claimed in Claim 1 or 2, characterized in that said actuating means (33,40) comprise rocker arm means (33) hinged onto the slide means (21) and fitted in a rotary manner with the splicing roller (44); and a linear actuator (40) located between the slide means (21) and the rocker arm means (33) for turning the rocker arm means (33) about a fulcrum (32), and for moving the splicing roller (44) to and from said operating position. A device as claimed in Claim 3, characterized in that said rocker arm means (33) comprise a rocker arm (33) which is substantially triangular in shape and has three tips; said fulcrum (32) being located on one of said tips of the rocker arm (33), and the splicing roller (44) and the linear actuator (40) engaging the rocker arm (33) on the other two tips.

Inventors: SACCO, TOMMASO
Applicants: BRIDGESTONE/FIRESTONE, INC.
Application year: 1987
Main classification: B29D30
IPC codes: B29D30, B29C53, B29C65