BEAD LOCK DEVICE IN TIRE FORMER

Abstract: A bead lock device in a tire which comprises a slide member (1) axially reciprocating movably fitted over a shaft (Fs) and a plurality of bead lock segments (2) circumferentially provided on the outer periphery of the slide member (1). A tapered surface (3) is formed on the outer peripheral surface of the slide member (1) and an inclined inner surface portion (21) for sliding on the tapered surface (3) due to an axial reciprocating motion of the slide member (1) to displace the segments (2) in the radial direction is formed on each of the bead lock segments (2).

Description: TECHNICAL FIELD This invention relates to a bead locking apparatus for a tyre building machine. BACKGROUND ART Conventionally a green tyre is a toroidal assembled but non-cured tyre which has been manufactured by assembling a cylindrical tyre cover on a tyre building machine. The machine comprises a drum which is supported rotatably on a shaft and the diameter of the building drum can be increased and decreased to allow the tyre beads to be held locked or unlocked. An example of a known bead locking apparatus for a tyre building machine is disclosed in FR-A-2294043. the conventional bead locking apparatus has any one or more of the following features: (1) the drum may be defined by a circumferential ring of drum segments, associated with means for moving each segment radially to expand the drum; each segment may be expanded by co-operation between a radially-inner inclined surface on the segment and a cam follower or driver driven by the moving means; (2) the generally cylindrical surface defined by the outer surfaces of the segments may be enclosed by a sleeve to enable the interior to be pressurised to support the tyre components between segments, and such sleeve may be elastic to be capable of expanding with the drum; (3) there may be a continuous expansible ring at or near each end of the drum and means for expanding it radially in relation to the drum to lock tyre components with beads positioned around them; such rings may be continuous elastic rings; axially driven wedges can co-operate with inclined cam surfaces to expand the rings; (4) expansion of the drum can be simultaneous with axially-inward movement of such lock rings so that the tyre components are not stretched during crowning; after expansion of the drum has been completed, a little further movement of the lock rings enables the carcass to be formed with an "undercut" at each side; axially beyond the drum, the drum surface may be continued as the surface of a flexible sleeve which is associated with actuators for deforming the sleeve outwardly to lash back the ends of the tyre components beyond the beads against the crown; the actuators may operate a circumferential ring of pivoted arms on link mechanisms causing first a radial outward movement and then a simultaneous axially inward and radial movement. The apparatus according to the prior art has a complex structure comprising the link mechanisms for deforming the flexible sleeve outwardly to lash back the ends of the tyre components beyond the beads against the crown. The link mechanisms circumferentially arranged at regular intervals can not evenly lash back the ends of the tyre components against the crown over the entire circumference because it is difficult to press against the entire circumference with a uniform force. DISCLOSURE OF THE INVENTION An object of the present invention is to provide a bead locking apparatus which has a simplified structure comprising a bladder as an alternative to the conventional flexible sleeve and link mechanism. The bladder is expanded by filling air to evenly lash back the ends of the tyre components beyond the beads against the crown. According to the present invention a bead locking apparatus for a tyre building machine comprises a sleeve member mounted on a shaft of a tyre building machine, the sleeve member having a cylinder adjacent to the shaft, a rear wall standing radially outwardly of the cylinder at a rear part thereof, an outer cylindrical wall extending forwardly from an outer end of the rear wall and a piston chamber formed from an annular space formed by the cylinder, the rear wall and the outer cylindrical wall, a readily detachable ring standing radially outwardly of a front part of the cylinder, an annular wall standing radially outwardly at a front end of the outer cylindrical wall, the annular wall and detachable ring being generally circumferentially parallel, the annular wall having generally the same radial height as the ring and defining a circumferential internal space with the ring, a circumferential outward mouth being formed between the annular wall and the ring, a slider mounted on the piston chamber, the slider being shaped to be formfitting to the piston chamber and being axially reciprocable between the rear wall and the ring, the slider being provided on an outer front surface with a tapering inclination which extends forwardly of the annular wall, a plurality of bead locking segments circumferentially arranged outwardly on the tapering portion in the circumferential space between the annular wall and the ring with each segment having a bottom surface formfitting to the tapering inclination of the slider such that the segments slide as the slider moves to thereby change radial height of the segments, an elastic ring circumferentially encircling over radially outer ends of the segments for providing a centripetal tension, and a bladder covering the circumferential outward mouth formed between the annular wall and the ring, the piston chamber being divided into a front chamber and a rear chamber and an opening being provided on the rear wall for supplying a fluid into the rear chamber and an opening being provided on a front end of the cylinder for supplying a fluid into the front chamber, wherein the fluid supplied into the front chamber communicates with the bladder for expansion of the bladder. Accordingly if, for example, the slider is axially moved by a certain force provided by a cylinder device each segment is displaced radially outwardly to make an expansion. The slider may preferably be contracted by means of the contraction force of a rubber band which is set around the segments. As a result of this mechanism, each segment slides on the slider tapered surface which it contacts by its inclined inner surface, and hence the segments change in radial height steplessly. Also the different height portions can be held positively and all portions have the same degree of support. The radial position of each segment is determined by the axial position at which the slider is stopped which means that a change of the slider axial position caused by air pressure to the cylinder effects a change of the bead locking diameter, and this changed position is locked effectively. Thus with a fixed power in the cylinder the work of locking various bead rings is permitted without restriction and thus providing stepless positioning. Further, the segments move on the tapered slider surface, the contact being by the segment inner surface, and thus effective bead locking can be carried out by a fixed, unchangeable power supply irrespective of the positioning of the segments provided that the stroke of the locking diameter can match the bead diameter concerned. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will now be described, by way of example only, in conjunction with the detailed diagrammatic drawings in which: Figure 1 is a cross sectional view from the side showing the contracted diameter; Figure 2 shows the expanded diameter portion; Figure 3 is an end scrap view of the segments in the contracted state; Figure 4 is an end view of the expanded state; and Figure 5 is a perspective view of a segment. BEST MODE FOR CARRYING OUT THE INVENTION In Figure 1 the machine has an axially reciprocable slide 1 in the form of a sleeve over a shaft Fs. A plurality of bead lock segments 2 are circumferentially arranged around an outer surface of the slider 1, wherein reciprocation of the slider 1 causes each segment 2 to be radially displaced and hence to provide as an assembly a tyre component locating surface which can be expanded or contracted diametrally. The slider 1 is composed of a ring member as shown in Figures 3 and 4, and has a tapered surface 3 on its outer side. Specifically, tapered surface 3 is a set of such tapered surfaces 3 formed on the outer face and on the front portion of the slider 1 so as to correspond to the set of segments 2. Therefore in the drawings eighteen sections of tapered surfaces are provided around the circumference. Also as shown in Figures 1 and 2, the slider 1 is provided, at its inner forward portion, with a counter bore or cut-out to provide at that end a stepped diameter 4 and on its outer face midway between its ends, with a circumferential groove 5. The slider 1 is slidably mounted on a sleeve member 6 which is fitted around the shaft Fs. The sleeve member 6 comprises a cylinder 7, a radially projecting wall 8 which extends from the cylinder 7, and an axially projecting wall 9 extending forwards from the end of the wall 8. The annual space or piston chamber 10 which is formed by the cylinder 7, the radial wall 8 and the axial wall 9, accommodates the slider 1. Further the sleeve member 6 is provided with fluid passages 11,12. The passage 11 has an opening 11a at the forward end of the piston chamber 10 and the passage 12 has an opening 12a at the rearward end of the piston chamber 10. If a fluid (e.g. air) flows in through the opening 11a, the fluid goes into a bladder 15. It is to be noted that the flow route does not move the slider 1 but if an inflow of fluid is through the opening 12a, the fluid flows into the piston chamber 10 and moves the slider 1 forwards as indicated in Figure 2. To ease fluid inflow into the piston chamber 10 the base end of the slide 1 has a cut 13a. At the forward end face of the sleeve member 6, a radially extending ring 14 is attached and on this ring 14, a holder 16 for retaining one end 15a of the bladder 15 is fitted with a fastening member 17, for example, a bolt. Thus one end 15a of the bladder 15 is nipped or fastened by the ring 14 and the holder 16. The ring 14 has a side facing groove 18 on its inner face, into which the forward end 19 of the slider 1 is designed to fit and enter. Between the inner face of the ring 14 and the forward end of the axial wall 9, a bead locking segment 2 is interposed. In detail the segment 2 has a circumferential groove 20 on its outer face and an inclined inner surface 21 to co-operate with and slide on the tapered surface 3 of the slider 1. As shown in Figure 5, on the forward face 22 and the inclined inner face 21, the segment 2 has a local recess 23,24 in which, as shown in Figures 1 and 2, a slide aid 25,26 is fitted to improve the slide action of the segments 2. In the groove 20 on the outer face of each segment 2, a rubber band 28 is fitted. This provides a band around the set of segments 2 and gives a centre petal face or radial binding face. As noted above, this embodiment herein has eighteen segments 2, though, this number is not essential. In operation, beginning with the slide 1 in the position shown in Figure 1, (that is with the base face 13 of the slider 1 abutted to the radial wall 8), the inner surface 21 of the segment 2 is positioned at the forward end of the slider tapered surface 3. This state is, in terms of expansion/contraction action, the contracted portion shown in Figure 3. Then, when the slider 1 resides at the portion shown in Figure 2 (that is with the forward end of the slider 1 engaged in the groove 18 of the ring 14), the inner surfaces 21 of the segments 2 are positioned at the base portion of the slider tapered surface 3, which state is that of Figure 4. To provide this operation, pressurised fluid is supplied through the opening 12a into the piston chamber 10 at the position shown in Figure 1, then the slider 1 moves forward as shown by a lateral arrow in Figure 2 and this causes the segment inner surfaces 21 to slide on the tapered surfaces 3, by which action the segments 2 are moved radially outwardly as shown by a vertical arrow in Figure 2 so that expansion results. When the fluid pressure in the piston chamber 10 is released, the Figure 2 state, through the opening 12a the contracting force of the rubber band 28 causes the segment inner surfaces 21 to slide on the slider tapered surfaces 3 as shown by a vertical arrow in Figure 1 so that the segments 2 move radially inwardly and the slider 1 moves to the base portion as shown by a lateral arrow in Figure 1. Thus, the elastic ring 28 performs the contraction of the segments 2. Also this provides protection of the bead lower portion from possible damage and relaxation of gaps between the segments 2. Referring now to the bladder 15, the other end 15b of the bladder 15 is fastened or nipped between the forward end portion 9a of the axial wall 9 and a holder 29 attached to the same end portion 9a. Accordingly, in the contracted state as shown in Figure 1 and 3, a portion (this portion is called here the "segment portion 15c") of the bladder 15 which covers or contacts over the segment 2, is not inflated, but in the expanded state as shown in Figures 2 and 4, the segment portion 15c of the bladder 15 is inflated. Thus, the machine diameter is changed between the state of Figure 1 and the state of Figure 2, so that a bead ring with an apex, not shown, is placed outside the segment portion 15c. Therein, radial movement of the segments 2 is guided by a guide member 30. The guide member 30 is composed of a rod which is secured to the forward end 9a of the axial wall 9 and engageable in the radial groove 32 formed on the base side face 31 of the segment 2. Further, axial movement of the slider 1 is guided by another guide member 33. The guide member 33 is attached to the slider 1 and engaged in an axial groove 34 formed in the axial wall 9. In shaping/building a tyre with use of this type of tyre building machine, materials for forming the carcass are wrapped onto the drum to form a cylindrical carcass and then the bead rings each with an apex are positioned on the segment portions 15c as noted above. The slider 1 is then axially moved to adjust the diameter at the segment portion 15c so as to match the bead ring and hold it. In the bead locking apparatus of the present invention, the slider 1, the segments 2, the sleeve member 8, the ring 14 and the holder 16 and other components are unitised and integrally mounted on the shaft Fs, which assembly offers a convenience in that the apparatus may be changed as a unit when a change in tyre size requires it. The invention is not limited to the embodiments as noted above and modifications or design changes within the scope of the tenor of the present invention as defined in the appended claims are included. For example, the inclination angle and length of the tapered surface 3 are a matter of design choice, and in correspondence thereto, the inclination angle and length of the inclined inner surface 21 is also the same. Further, in the disclosed embodiment, the tapered surface 3 of the slider 1 is designed to have an inclination to match with the inclination of the inner surface 21 of the segments 2, but such modification is obvious as to form a tapering on the forward end of the slider 1 into a cone shape. Further, the number of the segments 2 is free, the more segments which are used, the more approximation to a true circle. Practically 10 to 36 are preferred.

Claims: A bead locking apparatus for a tyre building machine comprising a sleeve member (6) mounted on a shaft (Fs) of a tyre building machine, the sleeve member (6) having a cylinder (7) adjacent to the shaft (Fs), a rear wall (8) standing radially outwardly of the cylinder (7) at a rear part thereof, an outer cylindrical wall (9) extending forwardly from an outer end of the rear wall (8) and a piston chamber (10) formed from an annular space formed by the cylinder (7), the rear wall (8) and the outer cylindrical wall (9), a readily detachable ring (14) standing radially outwardly of a front part of the cylinder (7), an annular wall (9a) standing radially outwardly at a front end of the outer cylindrical wall (9), the annular wall (9a) and detachable ring (14) being generally circumferentially parallel, the annular wall (9a) having generally the same radial height as the ring (14) and defining a circumferential internal space with the ring (14), a circumferential outward mouth being formed between the annular wall (9a) and the ring (14), a slider (1) mounted on the piston chamber (10), the slider (1) being shaped to be formfitting to the piston chamber (10) and being axially reciprocable between the rear wall (8) and the ring (14), the slider (1) being provided on an outer front surface (3) with a tapering inclination which extends forwardly of the annular wall (9a), a plurality of bead locking segments (2) circumferentially arranged outwardly on the tapering portion in the circumferential space between the annular wall (9a) and the ring (14) with each segment (2) having a bottom surface (21) formfitting to the tapering inclination of the slider (1) such that the segments (2) slide as the slider (1) moves to thereby change radial height of the segments (2), an elastic ring (28) circumferentially encircling over radially outer ends of the segments (2) for providing a centripetal tension, and a bladder (15) covering the circumferential outward mouth formed between the annular wall (9a) and the ring (14), the piston chamber (10) being divided into a front chamber and a rear chamber and an opening (12a) being provided on the rear wall (8) for supplying a fluid into the rear chamber and an opening (11a) being provided on a front end of the cylinder (7) for supplying a fluid into the front chamber, wherein the fluid supplied into the front chamber communicates with the bladder (15) for expansion of the bladder (15). A bead locking apparatus according to claim 1, characterised by the elastic ring (28) generally having a T-shape with a top portion and a base portion, the outer ends of the segments (2) each having a circumferential groove (20) and the base portion of the elastic ring (28) being positioned in the circumferential grooves (20) of the segments (2), the top portion of the elastic ring (28) covering the outer ends of the segments (2). A bead locking apparatus according to claim 1 or 2, characterised by further comprising a holder (16) detachably mounted on the detachable ring (14), an end (15a) of the bladder being mounted between the holder (16) and the ring (14). A bead locking apparatus according to claim 3, characterised in that the bladder (15) has a second end (15b) which is opposed to the end (15a) mounted between the holder (16) and the ring (14), and the bead locking apparatus further comprises an axially projecting wall extending from the rear wall (8), the axially projecting wall extending forward from the rear wall (8) and being spaced from the outer cylindrical wall (9), the second end (15b) of the bladder (15) being fastened to the axially projecting wall. A bead locking apparatus as claimed in claim 1, characterised by further comprising an axially projecting wall extending from the rear wall (8), the axially projecting wall extending forward from the rear wall (8) and being spaced from the outer cylindrical wall (9). A bead locking apparatus according to claim 5, characterised by further comprising a plurality of guide members secured to a forward end of the axially projecting wall, each of the bead locking segments (2) being slidably secured to guide members for radial displacement thereof, the bead locking apparatus further comprising a slider guide member attached to the slider and engageable in an axial groove formed in an interior of the axially projecting wall, the slider (1) being axially reciprocable along the slider guide member, the plurality of bead locking segments (2) being moved radially inwardly due to contracting force of the elastic ring when the slider moves rearward. A bead locking apparatus according to claim 1, characterised in that the slider (1), the bead locking segments (2), the sleeve member (6) and the ring (14) are unitised and integrally mounted on the shaft (Fs) of the tyre building machine.

Inventors: MIYANAGA YOSHINOBU RM BERUTOPI, OKUDA TAKAAKI, MIYANAGA,YOSHINOBU,, OKUDA, TAKAAKI,, MIYANAGA,YOSHINOBU, RM 1301 BERUTOPIA NISHIAKASHI, OKUDA, TAKAAKI, 21-114, OAZASHIRAIGAKESHITA
Applicants: SUMITOMO RUBBER IND, SUMITOMO RUBBER INDUSTRIES LTD.
Application year: 1991
Main classification: B29D30
IPC codes: B29D30, B29K21