CN210161628U - Tyre building drum for turning up tyre components - Google Patents

Abstract

The present invention relates to a tyre building drum for turning up a tyre component, wherein the tyre building drum comprises a drum axis, a plurality of arms, an arm support arranged for supporting the plurality of arms with respect to the drum axis, and a slope, wherein each arm is provided with a roller arranged to roll on the slope in a turning-up direction during a first phase of the turning up and to roll on the tyre component in the turning-up direction during a second phase of the turning up, wherein each arm further comprises a covering element, which is in a covering position between the roller and the tyre component at least during an initial part of the first phase of the turning up, wherein the covering element in the covering position protrudes beyond the roller axis in the arm direction towards the slope.

Description

Tyre building drum for turning up tyre components

Technical Field

The utility model relates to a tire constructs drum for rolling up tire component.

Background

WO01/68356a1 discloses a tyre building drum comprising a turn-up mechanism for building an unvulcanized tyre. The tyre building drum is provided with a set of radially extending hinge arms. Each arm is provided with a rewind roll. The tyre building drum further comprises means for moving each set of arms axially and radially from a first position, in which the turning-up rollers of the set of arms form a practically closed ring, to a second, extended position for turning-up and pressing a portion of the tyre component outside the bead against the extended portion of the tyre component inside the bead. The arm at the end near the turn-up roller is provided with a movable support surface which in the first position forms a practically closed cylindrical surface for supporting the tyre component. Before moving to the second position, the support surface moves in the arm direction from a first position, in which the turn-up roller is radially covered with respect to the outside, to a second retracted position, in which the roller is partially uncovered in the radially outward direction, so that the turn-up roller can contact and roll on the tire component during turning-up.

During turn-up, the turn-up roller initially rolls over the ramp towards the bead. When the turn-up roller approaches the bead, the turn-up roller contacts the ramp and the tire component. The rotation of the turn-up roller due to rolling on the ramp causes the tyre components supported on said turn-up roller to be fed into the nip between the turn-up roller and the bead. As shown in fig. 1, the residual length of the tire component that accumulates between the roller and the bead may result in creases, wrinkles, and/or air pockets between the tire component and the bead.

SUMMERY OF THE UTILITY MODEL

It is an object of the present invention to provide a tire building drum for turning up tire components, wherein the formation of creases, wrinkles and/or air pockets between the tire component and the bead during turning up can be reduced or does not occur.

According to a first aspect, the present invention relates to a tire building drum for turning up tire components, characterized in that the tire building drum comprises a drum axis defining an axial direction of the tire building drum, a plurality of arms distributed circumferentially around the drum axis, and an arm support arranged for supporting the plurality of arms with respect to the drum axis, wherein each arm has a proximal end hingeably coupled to the arm support such that the arm is rotatable with respect to the arm support in a turning up direction in a turning up plane extending in a radial direction with respect to the drum axis, wherein the tire building drum comprises a ramp, wherein each arm has a distal end opposite the proximal end and an arm body extending in an arm direction between the proximal end and the distal end, wherein each arm is provided with a roller at the distal end, the roller is rotatable with respect to the arm about a roller axis, wherein the roller is arranged to roll on the ramp in the turning-up direction during a first phase of the turning-up and to roll on the tire component in the turning-up direction during a second phase of the turning-up, wherein each arm further comprises a cover element arranged to be in a cover position between the roller and the tire component at least during an initial part of the first phase of the turning-up, wherein the cover element in the cover position is arranged to protrude towards the ramp beyond the roller axis in the arm direction, wherein the cover element forms a cover surface for contacting the tire component during the initial part of the first phase of the turning-up.

The covering element may effectively shield and/or separate the tire component from the roller during said initial part of the first stage of the turn-up such that gathering of the tire component between the nip of the roller and the bead is reduced or does not occur. This is particularly effective for tire components having reinforcing cords extending in radial planes, the friction between the cover element and the tire component tending to pull the reinforced (and thus less stretchable) tire component tightly around the bead, thereby preventing wrinkles and/or air pockets. When the roller finally contacts the tyre component, the arm is already in a more advantageous orientation for turning up, in which orientation the roller is less likely to return the tyre component into the nip between the roller and the bead. Thus, the formation of creases, wrinkles, and/or air pockets between the tire component and the bead during turn-up may be reduced or not occur.

In a preferred embodiment, the roller has a circumference for contacting the chamfer and the tire component, wherein the cover element in the cover position is arranged to protrude beyond the circumference of the roller in the arm direction towards the chamfer. Thus, the covering element according to this embodiment may shield a substantial part of the circumference of the roller with respect to the tire component during the initial part of the first stage of the turn-up. In particular, the covering element may keep the tyre component separated from the roller at least up to a point on the circumference of the roller facing in the arm direction.

In another embodiment, the tire building drum comprises bead locking members forming bead support surfaces for supporting beads at a radial distance from the drum axis, wherein each cover element in the covering position protrudes in the arm direction towards the ramp surface beyond the roller axis by a first protrusion distance, wherein the first protrusion distance is selected such that the cover element in the covering position protrudes in the axial direction towards the ramp surface beyond the circumference of the roller at least until the roller axis is at the same radial distance from the drum axis as the bead support surfaces with respect to the drum axis. Above said radial distance, the roller has almost reached the end of the ramp or has left the ramp and is ready to turn up the tyre component around the bead. Thus, the rollers are less likely to return tire components into the nip between the rollers and the beads.

In one embodiment thereof, the first protrusion distance is selected such that the cover element protrudes in the arm direction towards the ramp over a second protrusion distance of the circumference of the roller, the second protrusion distance being in the range of zero to ten millimeters. The more the covering element protrudes, the more effective it is in terms of a shading roller. However, if the selected second protrusion distance is too large, the cover element may bite into the tire component.

In another preferred embodiment, the arm direction of each arm extends at an increasing turn-up angle relative to the drum axis during turn-up, wherein the cover element is arranged in the cover position until the turn-up angle is at least five degrees. Thus, for at least the first five degrees of rollover, the cover element is arranged to shield the roller from the tire component.

In another embodiment, the cover element is fixed in the cover position relative to the respective arm of the cover element. Thus, the cover element may remain in the covering position during the entire rollover. No actuators or control of the position of the covering elements are required, which may simplify the tyre building drum. The contact moment between the roller and the tyre component is passively defined by the shape and/or size of the covering element (e.g. the first or second protrusion distance with respect to the turn-up angle).

In another embodiment, the cover element comprises a cover body and a front end portion protruding from the cover body in the arm direction towards the ramp surface beyond the roller axis, wherein the front end portion is deflected from the arm direction towards the roller axis. The deflected front end portion may reduce the tendency of the front end portion to bite into the tire component. Furthermore, the deflected front end portion may follow the circumference of the roller more closely, thereby more effectively shielding the circumference from the tire component.

In an alternative embodiment, the cover element comprises a rear end opposite the front end, wherein the rear end is deflected from the arm direction towards the roller axis. Preferably, the cover body, the front end portion and the rear end portion extend along a curvature concentric or substantially concentric with the roller axis. Thus, the deflected front end portion and the deflected rear end portion may form a covering element similar to a wheel cover. In particular, the covering element can follow the circumference of the roller more closely on both sides of the roller axis in the arm direction.

In another embodiment, the cover surface is arcuate and extends concentrically or substantially concentrically with the drum axis. Because the cover surface extends concentrically or substantially concentrically with the drum axis, the cover surface can more closely follow the circumference of the tire building drum. In particular, the transition from one mantle surface to an adjacent mantle surface in the circumferential direction may be made less abrupt. This may minimize marking on the relatively soft material of the tire component.

According to a second aspect, the present invention relates to a tire building drum for turning up tire components, characterized in that the tire building drum comprises a drum axis defining an axial direction of the tire building drum, a plurality of arms distributed circumferentially around the drum axis, and an arm support arranged for supporting the plurality of arms with respect to the drum axis, wherein each arm has a proximal end hingeably coupled to the arm support such that the arm is rotatable with respect to the arm support in a turning up direction in a turning up plane extending in a radial direction with respect to the drum axis, wherein the tire building drum comprises a ramp, wherein each arm has a distal end opposite the proximal end and an arm body extending in an arm direction between the proximal end and the distal end, wherein each arm is provided with a roller at the distal end, the roller being rotatable with respect to the arm about a roller axis, wherein the roller is arranged to roll on the ramp in the turning-up direction during a first phase of the turning-up and to roll on the tire component in the turning-up direction during a second phase of the turning-up, wherein each arm further comprises a cover element arranged to be in a cover position between the roller and the tire component at least during an initial part of the first phase of the turning-up, wherein the cover element in the cover position is arranged to protrude towards the ramp in the arm direction beyond the roller axis, wherein the cover element forms a cover surface for contacting the tire component during the initial part of the first phase of the turning-up, wherein the cover element is retractable from the cover position to a retracted position in the arm direction, in the retracted position, the covering element is located on the opposite side of the roller axis with respect to the covering position, wherein the tyre building drum further comprises an actuator for positioning the covering element in the covering position at least during an initial part of the first phase of the turn-up and for retracting the covering element to the retracted position after the initial part of the first phase of the turn-up has been completed. In this actively controlled embodiment, an actuator may be used to initially position the cover element in the covering position and retract the cover element once the arm has turned up sufficiently to cause the roller to begin turning the tire component. Due to the active retraction, the shape and/or size of the covering element does not necessarily need to closely follow the roller. Instead, the covering element may simply be retracted after completion of the initial part of the first stage of the rolling-up.

In one embodiment thereof, the tire building drum comprises bead locking members forming bead support surfaces for supporting beads at a radial distance from the drum axis, wherein the actuator is arranged for retracting the covering element to the retracted position when or after the roller axis is at the same radial distance from the drum axis as the bead support surfaces. Above said radial distance, the roller has almost reached the end of the ramp or has left the ramp and is ready to turn up the tyre component around the bead. Thus, the rollers are less likely to return tire components into the nip between the rollers and the beads.

In a further embodiment thereof, the actuator is arranged to retract the cover element during an initial part of the first stage of the turning-up to an intermediate position between the cover position and the retracted position, wherein the cover element in the intermediate position is arranged to protrude beyond the roller axis in the arm direction towards the ramp. By retracting the cover element slightly, but not completely, towards the retracted position, the amount of protrusion of the cover element beyond the roller axis may be reduced. Thus, during said initial part of the first stage of the turning up, the tendency of the covering element to bite into the tyre component may be reduced.

The various aspects and features described and illustrated in the specification may be applied separately wherever possible.

Drawings

The invention will be elucidated on the basis of exemplary embodiments shown in the appended schematic drawings, in which:

figure 1 shows a side view of a tyre building drum for turning up tyre components according to the prior art;

figure 2 shows a side view of a tyre building drum for turning up tyre components according to a first embodiment of the present invention;

3A, 3B, 3C show side views of the tyre building drum according to FIG. 2 during different steps of turning up the tyre components;

4A, 4B, 4C show side views of an alternative tyre building drum according to a second embodiment of the present invention during different steps of the turning up of the tyre components;

5A, 5B, 5C show side views of a further alternative tyre building drum according to a third embodiment of the present invention during different steps of the turning up of the tyre components; and

fig. 6 shows a front view of a further alternative tyre component according to a fourth embodiment of the present invention.

Detailed Description

Fig. 2 and fig. 3A, 3B and 3C show a tire building drum 1 for turning up a tire component 9 according to a first exemplary embodiment of the present invention. The tire component 9 may be a single tire layer or a package of multiple tire layers. Preferably, the tyre components 9 comprise cord reinforced plies, such as carcass plies for green tyres.

As shown in fig. 2, the tire building drum 1 comprises a drum axis S defining an axial direction a of the tire building drum 1. The tire building drum 1 has a drum shaft 10 extending along the drum axis S. The drum shaft 10 is arranged to carry two drum halves on opposite sides of the centre M of the tyre building drum 1. In fig. 2, only one drum half 11 is shown. The drum shaft 10 is supported in a housing (not shown) which further houses a rotary drive for rotating the tire building drum 1 about its drum axis S, and one or more drive members operatively connected to various portions of the tire building drum 1 to control the operation of the tire building drum during turn-up. The drum half 11 comprises a bead locking member 2 having a bead support surface 20 for supporting the bead 8 at a radial distance D from the drum axis S. Preferably, the bead locking members 2 are movable and/or expandable in the radial direction R with respect to the drum axis S to grip the beads 8 from the inside. The bead 8 is arranged on the tyre component 9, wherein a first portion 91 of the tyre component 9 extends on one side of the bead lock member 2 for shaping and a second portion 92 of the tyre component 9 extends on the other side of the bead lock member 2 for turning.

The drum half 11 comprises a plurality of arms 3 which are distributed circumferentially about the drum axis S in a manner known to the person skilled in the art. The arm 3 is located at the opposite side of the bead lock member 2 from the center M of the tire building drum 1. The second portion 92 of the tyre component 9 extends towards said arm 3 and at least partly over said arm 3 and is ready to be turned around the bead 8 and towards and/or onto the first portion 91 of the tyre component 9. The drum half 11 is provided with an arm support 4 for supporting the plurality of arms 3 with respect to the drum axis S. Although fig. 2 shows only a single arm 3, it will be clear to the skilled person that said arm 3 and its operation represent all arms 3 circumferentially distributed around the drum axis S of the tyre building drum 1. In this exemplary embodiment, the arm support 4 is arranged around the drum shaft 10 and is movable on the drum shaft 10 in the axial direction a. Each arm 3 has a proximal end 31 hingeably coupled to an arm support 4 such that the respective arm 3 is rotatable relative to said arm support 4. In particular, each arm 3 is rotatable with respect to the arm support 4 in a respective overturning direction T in a respective overturning plane P extending in the radial direction R with respect to the drum axis S. The arm 3 is rotatable between an underarm position, from which it is shown in fig. 3A, in the turning-up direction T towards an upper-arm position (not shown), in which the arm 3 has completed the turning-up of the second portion 92 of the tyre component 9 around the bead 8 and/or against or onto the shaped first portion 91 of the tyre component 9.

As shown in fig. 2, drum half 11 also includes ramp 5 for arm 3 to rise and ride over. Specifically, when the arm support 4 moves in the axial direction a toward the ramp 5, the axial movement forces the arm 3 up and over the ramp 5. It should be noted that the shape of the bevel 5 in fig. 2 is one of many possible shapes. The shape of the ramp 5 may be adapted to the desired path followed by the arm 3 during the rollover. In fig. 2, the scrolling direction T has been simplified to an arc-shaped arrow. However, it will be apparent to those skilled in the art that the path followed by the arm 3 may be more complex and may include variable vector components in the axial direction a and the radial direction R.

As best shown in fig. 2, each arm 3 has a distal end 32 opposite the proximal end 31 and an arm body 30 extending in an arm direction L between the proximal end 31 and the distal end 32. Each arm 3 is provided at a distal end 32 with a roller 33 which is rotatable with respect to said arm 3 about a roller axis X. The roller 33 has a circumference 34 which, as shown in fig. 3A and 3B, is arranged for contacting the ramp 5 and/or rolling over the ramp 5 in the turning-up direction T during a first phase of the turning-up, and which, as shown in fig. 3C, is arranged for contacting the second portion 92 of the tyre component 9 and/or rolling over the second portion 92 of the tyre component 9 in the turning-up direction T during a second phase of the turning-up. The roller 33 is preferably freely rotatable.

As best shown in fig. 3A, 3B and 3C, each arm 3 further comprises a covering element 6 arranged to extend in a covering position between the roller 33 and the tyre component 9. The cover element 6 comprises a cover body 60, a front end 61 facing the ramp 5 and a rear end 62 coupled to the arm body 30. The cover body 60 extends from the arm body 30 towards the roller 33 and at least partially over the roller 33 at a side of said roller 33 facing the second portion 92 of the tyre component 9. The cover body 60 is non-rotatable and/or rotationally fixed with respect to the arm 3. In this exemplary embodiment, the cover body 60 is rigidly and/or fixedly mounted to the arm 3 so as to be fixed relative to the arm 3 in said covering position.

The front end 61 is deflected from the arm direction L towards the roller axis X to prevent said front end 61 from biting into and/or damaging the tyre component 9 during the turning up. In particular, said front end 61 extends along a curvature concentric or substantially concentric to the roller axis X. The cover body 60 and the rear end portion 62 extend from the roller 33 toward the arm body 30 in parallel or substantially parallel to the arm direction L. Specifically, the rear end 62 spans the gap between the roller 33 and the arm body 30 to provide a more uniform surface for the second portion 92 of the tire component 9.

As shown in fig. 3A, the covering element 6 in the covering position is arranged to project or protrude beyond the roller axis X in the arm direction L towards the ramp 5. More specifically, the covering element 6 in the covering position is arranged to protrude beyond the circumference 34 of the roller 33 in the arm direction L. Thus, in said covering position, at least during the initial part of the first phase of the turning-up, the covering element 6 can effectively shield and/or separate the roller 33 from the tyre component 9, as shown in fig. 3A and 3B. More specifically, the covering element 6 is preferably arranged to shield and/or separate the roller 33 from the tyre component 9 at least until the roller axis X is at the same radial distance D from the bead support surface 20 with respect to the drum axis S. At this radial distance D, the roller 33 has reached the end of the bevel 5 and/or is at the same height as the bead 8. Thus, the roller 33 may now start to contact and roll on the second portion of the tyre component 9.

It has been found that it is preferable to have each covering element 6 project in the arm direction L towards the ramp 5 beyond the roller axis X by a first projection distance E1 chosen such that the covering element 6 still projects in the axial direction a towards the ramp 5 beyond the circumference 34 of the roller 33, at least until the roller axis X is at the same radial distance D with respect to the drum axis S as the bead support surface 20. More preferably, the first projecting distance E1 is chosen such that the covering element 6 projects in the arm direction L towards the ramp 5 beyond the circumference 34 of the roller 33 by a second projecting distance E2, which is in the range of zero to ten millimetres.

In the exemplary embodiment shown in the figures, the covering element 6 is fixed and therefore remains in the covering position throughout the first and second phases of the rolling. Only the shape and/or dimensions, e.g. the projection distances E1, E2, are carefully selected to ensure that the roller 33 contacts the tyre component 9 only at the moment when the arm 3 is at the appropriate turning angle H with respect to the drum axis S. Preferably, the covering element 6 is designed such that the arm 3 is at a turn-up angle H of at least five degrees when the roller 33 first contacts the tyre component 9. It should be noted that the arm 3 may be in a slightly offset underarm position, i.e. an axial direction a that is not completely horizontal and/or parallel to the drum axis S. Therefore, the difference between the roll-up angle H of the arm 3 in the underarm position and the roll-up angle H of at least five degrees specified above may be less than five degrees. Preferably, the specified turn-up angle H is selected such that the arm 3 is offset by at least five degrees relative to the orientation of the arm 3 in the underarm position when the roller 33 first contacts the tire component 9.

As further shown in fig. 2, each arm 3 is provided with a deck (deck)7 extending in circumferential direction of the tyre building drum 1 towards the deck 7 of the adjacent arm 3. The deck 7 serves to reduce the gap between the arms 3. Preferably, the deck 7 is adapted to form a substantially closed and/or seamless circumferential surface when the arm 3 is in the underarm position as shown in fig. 3A. In the exemplary embodiment, each deck 7 is fixed to its respective arm 3 or relative to its respective arm 3 in the arm direction L. Thus, the deck 7 is stationary relative to the arms 3.

Fig. 4A, 4B and 4C show an alternative tyre building drum 101 according to a second embodiment of the present invention. The alternative tyre building drum 101 differs from the previously discussed tyre building drum 1 in that its arm 3 is provided with an alternative covering element 106 which is movable in the arm direction L from a covering position as shown in fig. 4A and/or retractable to a retracted position as shown in fig. 4C. In the covering position, in the same way as the covering element 6 according to the first embodiment of the invention, the alternative covering element 106 protrudes in the arm direction L a first protruding distance E1 beyond the roller axis X and a second protruding distance E2 beyond the circumference 34 of the roller 33. However, in the retracted position, the alternative cover elements 106 are retracted to and/or located on opposite sides of the roller axis X relative to the covered position. With the alternative covering element 106 in the retracted position, the roller 33 is at least partially exposed to the tyre component 9. Thus, the optional covering element 106 no longer shields and/or separates the roller 33 from the tire component 9.

As shown in fig. 4A, 4B and 4C, the alternative tire building drum 101 comprises an actuator 111, such as a piston or a drive nut, for actively positioning the alternative covering element 106 in a covering position at least during an initial portion of the first stage of the turn-up. The actuator 111 may be connected to the rear end 162 of the optional cover element 106. The actuator 111 is arranged to retract the alternative covering element 106 to the retracted position after completion of an initial part of the first stage of the rollover.

Because the alternative cover element 106 is actively retracted, its shape and/or size does not necessarily have to be selected to passively expose the roller 33. Instead, the shape or size of the alternative covering element 106 may be optimized for providing a uniform support surface for the tire component 9 in the underarm position, as shown in fig. 4A, and the alternative covering element 106 may be actively retracted upon completion of the initial portion of the first stage of the turn-up. Thus, the cover body 160 and the front end 161 of the alternative cover element 106 may protrude or protrude further than the previously discussed cover element 6 beyond the roller axis X. The front end 161 may even extend to the bevel 5 or close to the bevel 5 to close the gap between the roller 33 and said bevel 5.

As shown in fig. 4C, the actuator 111 is arranged to retract the alternative covering element 106 to the retracted position when or after the roller axis X is at the same radial distance D relative to the drum axis S as the bead support surface 20. In order to prevent the leading end 161 of the alternative covering element 106 from biting into the tire component 9 during the first stage of the turning up, the actuator 111 may optionally be arranged for retracting the alternative covering element 106 to an intermediate position between the covering position and the retracted position, as shown in fig. 4B. In the intermediate position, the alternative covering element 106 is arranged to still protrude beyond the roller axis X in the arm direction L towards the ramp 5. However, the first protrusion distance E1 is reduced or shorter than the first protrusion distance E1 in the covering position of fig. 4A. The movement from the covering position to the intermediate position and from the intermediate position to the retracted position may be a stepwise movement or a gradual movement.

Fig. 5A, 5B and 5C show a further alternative tyre building drum 201 according to a third embodiment of the present invention. Said further alternative tyre building drum 201 differs from the tyre building drums 1, 101 previously discussed in that its arm 3 is provided with a further alternative covering element 206, which fits over the roller 33 like a wheel house. In particular, the further alternative covering element 206 comprises a front end 261 and a rear end 262, which are offset from the arm direction L towards the roller axis X on opposite sides of the covering body 260. More specifically, the cover body 260, the front end 261 and the rear end 262 all extend along a curvature that is concentric or substantially concentric with the roller axis X. Thus, the further alternative cover elements 206 may be positioned next to the roller 33 at a pitch of, for example, less than two millimeters.

Again, the front end 261 projects or protrudes beyond the roller axis X, in particular beyond the circumference 34 of the roller 33, in the arm direction L, in order to effectively shield and/or separate said roller 33 from the tire component 9. In this exemplary embodiment, the further alternative cover element 206 extends along at least a quarter of the circumference 34 of the roller 33 and preferably along at least half of the circumference 34 of the roller 33. In an alternative embodiment (not shown), the further alternative covering element 206 may cover more than half, for example three quarters, of the circumference 34 of the roller 33 and expose only that part of the roller 33 which is arranged to be in contact with the tyre component 9 during the second stage of turning.

Similar to the covering element 6 of the first embodiment, a further alternative covering element 206 according to a third embodiment of the invention is fixed in a covering position with respect to the arm 3.

The further alternative tyre building drum 201 may optionally be provided with a plurality of alternative decks 207 extending between the plurality of arms 3 in the underarm position to reduce the gap between the plurality of arms 3. Unlike deck 7 previously discussed, the alternative deck 207 is not mounted or provided on the arm 3. Instead, the alternative deck 207 extends between the arms 3 only when the arms 3 are in the underarm position, as shown in fig. 5A, and is supported on or relative to the drum shaft 10. Thus, when the arm 3 is rotated from the underarm position towards the on-arm position, the alternative deck 207 does not roll over with the arm 3, but remains stationary in the radial direction R.

The alternative deck 207 is movable in the axial direction a between a closed position as shown in fig. 5A and an open position as shown in fig. 5B and 5C. In the closed position, each alternative deck 207 extends at least partially over or alongside a respective one of the further alternative cover elements 206 to reduce or close the gap between the arms 3 and further to reduce or close the gap between the roller 33 and the ramp 5 or the gap between the roller 33 and the arms 3. In the closed position, the alternative deck 207 obstructs the arm 3, the roller 33 and/or the further alternative covering element 206. Thus, for the first stage of the turn-up, in order to release the arms 3, the rollers 33 and/or the further alternative covering elements 206, the alternative decks 207 can be moved into an open position in which the plurality of decks 207 no longer obstruct the arms 3, the rollers 33 and/or the further alternative covering elements 206, but release them for movement in the turn-up direction T. The alternative deck 207 thus covers the roller 33 only in the underarm position and moves to the open position shown in fig. 5B before the first stage of the roll-up, in particular when the arm 3 is still in the underarm position shown in fig. 5A.

Fig. 6 shows a further alternative tyre building drum 301 according to a fourth embodiment of the present invention. The further alternative tyre building drum 201 differs from the previously discussed further alternative tyre building drum 201 according to the third embodiment of the present invention in that it is provided with a further alternative covering element 306 forming a covering surface 363 for contacting the tyre component 9 during an initial part of the first stage of the turning up, wherein said covering surface 363 is arc-shaped around the drum axis S. Preferably, said covering surface 363 extends concentrically or substantially concentrically with the drum axis S, in particular when the arm 3 is in the underarm position. Thus, the cover surface 363 may closely follow or be concentric with the circumferential direction C of the alternative tire building drum 301. Thus, the transition from one mantle surface 363 to another mantle surface in the circumferential direction C may be made less abrupt and/or smoother. Preferably, the edges of the further alternative cover element 306 in the circumferential direction C are provided with a slight chamfer or fillet to prevent damage to the tyre component 9 supported on the curved cover surface 363.

As further shown in fig. 6, each arm 3 may optionally be provided with a first roller 333 and a second roller 334 rotatably mounted to said arm 3 about a first roller axis X1 and a second roller axis X2, respectively. The roller axes X1, X2 are preferably arranged at an angle such that the circumferences of the two rollers 333, 334 tangentially adjoin the circumferential direction C of the further alternative tyre building drum 301. This may distribute the pressure exerted by the rollers 333, 334 more evenly over the tyre component 9.

In a further embodiment thereof, one or more drives are arranged for positioning and holding the arm support 4 in position such that each roll-up arm 3 is turned up and temporarily held in an intermediate position between the underarm position and the on-arm position, as shown in fig. 3C, 4C and 5C. In said intermediate position, the turning arm 3 may support one or more layers of the green tyre during the application or stitching of said layers on the circumferential surface of the tyre building drum 1.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.

List of reference numerals

1 tyre building drum

10 drum shaft

11 drum half

2 bead Lock Member

20 bead support surface

3 arm

30 arm body

31 proximal end

32 distal end portion

33 roller

34 circumference of circle

35 arm support surface

4 arm support

5 inclined plane

6 covering element

60 cover body

61 front end part

62 rear end part

7 Deck

8 tyre bead

9 tire component

91 first part

92 second part

101 optional tyre building drum

106 optional cover element

160 cover body

161 front end part

162 rear end portion

111 actuator

201 additional alternative tyre building drum

206 additional alternative cover elements

207 optional deck

260 cover body

261 front end portion

262 rear end portion

301 alternative tyre building drum

333 first roller

334 second roller

306 additional alternative cover element

360 cover the body

363 arc-shaped cover surface

Axial direction A

C circumferential direction

D radial distance

E1 first projection distance

E2 second projection distance

H roll angle

Direction of L arm

M center

P rolling plane

R radial direction

S drum axis

T direction of rolling

Axis of X roller

X1 first roll axis

X2 second roll axis

Claims (10)

1. Tyre building drum for turning up tyre components, characterized in that the tyre building drum comprises a drum axis defining an axial direction of the tyre building drum, a plurality of arms distributed circumferentially around the drum axis and an arm support arranged for supporting the plurality of arms with respect to the drum axis, wherein each arm has a proximal end hingeably coupled to the arm support such that the arm is rotatable with respect to the arm support in a turning-up direction in a turning-up plane extending in a radial direction with respect to the drum axis, wherein the tyre building drum comprises a ramp, wherein each arm has a distal end opposite to the proximal end and an arm body extending in an arm direction between the proximal end and the distal end, wherein each arm is provided with a roller at the distal end, the roller is rotatable with respect to the arm about a roller axis, wherein the roller is arranged to roll on the ramp in the turning-up direction during a first phase of the turning-up and to roll on the tire component in the turning-up direction during a second phase of the turning-up, wherein each arm further comprises a cover element arranged to be in a cover position between the roller and the tire component at least during an initial part of the first phase of the turning-up, wherein the cover element in the cover position is arranged to protrude towards the ramp beyond the roller axis in the arm direction, wherein the cover element forms a cover surface for contacting the tire component during the initial part of the first phase of the turning-up.

2. Tyre building drum according to claim 1, wherein the roller has a circumference for contacting the ramp and the tyre component, wherein the cover element in the cover position is arranged to protrude beyond the roller circumference in the arm direction towards the ramp.

3. Tyre building drum according to claim 1, characterized in that the tyre building drum comprises bead locking members forming bead support surfaces for supporting beads at a radial distance from the drum axis, wherein each cover element in the covering position protrudes in the arm direction towards the ramp over the roller axis by a first protrusion distance, wherein the first protrusion distance is selected such that the cover element in the covering position protrudes in the axial direction towards the ramp over the circumference of the roller at least until the roller axis is at the same radial distance from the bead support surface with respect to the drum axis.

4. Tyre building drum according to claim 3, wherein the first projection distance is selected such that the covering element projects in the arm direction towards the ramp over a second projection distance of the circumference of the roller, the second projection distance being in the range of zero to ten millimetres.

5. Tyre building drum according to claim 1, wherein the arm direction of each arm extends at an increasing turn-up angle relative to the drum axis during turn-up, wherein the covering element is arranged in the covering position until the turn-up angle is at least five degrees.

6. Tyre building drum according to claim 1, wherein the covering element is fixed in the covering position with respect to the respective arm of the covering element.

7. Tyre building drum according to claim 1, wherein the cover element comprises a cover body and a front end portion, which front end portion protrudes from the cover body in the arm direction towards the ramp surface beyond the roller axis, wherein the front end portion is deflected from the arm direction towards the roller axis.

8. Tyre building drum according to claim 7, wherein the cover element comprises a rear end opposite the front end, wherein the rear end is deflected from the arm direction towards the roller axis.

9. Tyre building drum according to claim 8, wherein the cover body, the front end and the rear end extend along a curvature concentric with the roller axis.

10. Tyre building drum according to claim 1, characterized in that the cover surface is arc-shaped and extends concentrically or substantially concentrically to the drum axis.

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