Patent Description:
<CIT> discloses a tire building machine having a tire building drum, in particular a crown drum for single stage tire building, comprising two drum halves. Each drum half comprises a crown-up section, a turn-up section and a bead-lock section that is located in the axial direction between the crown-up section and the turn-up section. The bead-lock section comprises a plurality of bead-lock members distributed circumferentially about a central axis and movable in the radial direction between a release position and a bead-lock position.

Further tire building machines comprising a tire building drum and a stitcher for stitching a tire component are disclosed in documents <CIT>, <CIT> and <CIT>.

A disadvantage of the known tire building according to <CIT> is that in some cases a side wall needs to be applied by folding said side wall around the radially inner side of the bead, in particular between the bead and the drum. The folding of the sidewall around the radial inner side of the bead is particularly difficult because the sidewall forms a skirt along the bead that is hard to fold consistently around the radial inner side of the bead. This cannot be done manually. However, the available space between the bead and the bead-lock members in the release position is only a few millimeters and insufficient to accommodate a conventional stitching roller. Hence, the drum halves need to be at least partially moved away in the axial direction to allow folding of a side wall around the bead. Alternatively, the side wall has to be folded around the bead on a first drum with a smaller diameter, after which the tire components have to be transferred to a shaping drum, as is the case in conventional two stage tire building.

It is an object of the present invention to provide a stitcher, a tire building machine comprising said stitcher and a method for stitching a tire component, with an improved approach to applying the side wall.

According to a first aspect, the invention provides a tire building machine comprising a tire building drum and a stitcher for stitching a tire component, wherein the tire building drum comprises bead-lock segments which are retractable into a recessed position relative to the rest of the tire building drum, wherein the stitcher comprises a disc-shaped stitching body having a first side for pressing on the tire component during stitching and a second side opposite to the first side, wherein the second side is concave, wherein the stitcher is positionable relative to the tire building drum such that the concave second side fits at least partially over a transition between the bead-lock segments in the recessed position and the rest of the tire building drum.

Because of the concave second side, the stitcher according to the first aspect of the invention can be moved closer to the circumference of the tire building drum without colliding, in particular at said transition or transition edge, so that the stitcher can reach into the relatively small space between the retracted bead-lock segments and the radially inner side of the bead.

Preferably, the disc-shaped stitching body is concentric about a stitching axis, wherein the first side defines a pressing surface that is arranged at a slope that is inclined away from the second side at a clearance angle in a radial direction away from the stitching axis. More preferably, the clearance angle is in a range of zero to fifteen degrees, and most preferably in a range of two to ten degrees. Because of the clearance angle, the stitcher can be scooped underneath the radially inner side of the bead with the stitching axis at an oblique angle to a vertical plane, thereby tilting at least a part of the pressing surface towards or into a horizontal plane. The pressing surface can thus effectively fold and press the tip of the tire component around the radially inner side of the bead while the stitcher is arranged at an oblique angle to the tire building drum.

According to a second aspect, the invention provides a method for stitching a tire component with the use of a tire building machine according to the first aspect of the invention, wherein the method comprises the step of:.

The method relates to the practical implementation of the aforementioned tire building machine and thus has the same technical advantages, which will not be repeated hereafter.

Preferably, the disc-shaped stitching body is concentric about a stitching axis, wherein the first side defines a pressing surface that is arranged at a slope that is inclined away from the second side at a clearance angle in a radial direction away from the stitching axis, wherein the method comprises the step of:.

In said horizontal or substantially horizontal orientation, the pressing surface can effective fold and press onto the tip of the tire component from within the bead.

According to a third aspect, the present disclosure provides a stitcher for stitching a tire component, wherein the stitcher defines a primary stitching axis and comprises a primary stitching member concentric to and rotatable about said primary stitching axis for stitching the tire component along a first part of a stitching path, wherein the stitcher further comprises a secondary operational member and a positioning member for moving the secondary operational member relative to the primary stitching axis into an active position in which the secondary operational member partially projects beyond the primary stitching member in a radial direction perpendicular to the primary stitching axis, wherein the positioning member is rotatable about the primary stitching axis, wherein the rotation of the positioning member is arranged to be driven by Eddy current generated between said positioning member and the primary stitching member.

The secondary operational member can be dimensioned or optimized to fit into a space into which the primary stitching member can not fit. More in particular, the secondary operational member can fit in the relatively small space between the bead-lock members and the radial inner side of the bead. The forces generated by Eddy current can be used to pull along the positioning member as the primary stitching member rotates. Therefore, no separate drive means is necessary to drive the positioning member.

In one embodiment the secondary operational member is a secondary stitching member for stitching the tire component along a second part of the stitching path. The secondary stitching member can fit in the relatively small space between the bead-lock members and the radial inner side of the bead to stitch and/or fold the sidewall along the radial inner side of the bead.

Preferably, the stitcher defines a secondary stitching axis, wherein the secondary stitching member is concentric to and rotatable about said secondary stitching axis. The secondary stitching member can thus stitch and/or fold the sidewall while the drum with the sidewall and bead supported thereon are being rotated, with a minimal amount of friction.

In a further embodiment the rotation of the positioning member about the primary stitching axis is arranged to be driven by the rotation of the primary stitching member. Therefore, no separate drive means is necessary to drive the positioning member.

In a further embodiment the positioning member is rotatable between a standby position in which the secondary operational member is spaced apart from the tire component during stitching and the stitching position. Hence, the secondary operational member can be switched, moved and/or rotated between said positions depending on the stitching operation that is being performed.

In a further embodiment the stitcher comprises a first limiter and a second limiter for limiting the rotation of the positioning member between the standby position and the active position. Consequently, the secondary operational member can be moved between said two positions. In particular, it can be prevented that the positioning member is moved beyond said two positions where the secondary operational member can potentially interfere with the operation of the primary stitching member.

In a further embodiment comprises the first limiter and the second limiter limit the rotation of the positioning member to a range of less than one-hundred-and-eighty degrees. Consequently, the positioning member can be moved between two positions that are spaced apart over one-hundred-and-eighty degrees or less.

In a further embodiment the positioning member is configured for rotating in the same direction about the primary stitching axis as the primary stitching member. Hence, the direction of rotation of the primary stitching member can be used to control the direction of rotation of the positioning member.

In another embodiment, the positioning member is provided with a plurality of magnets. The rotation of the primary stitching member through the magnetic fields generated by the plurality of magnets on the positioning member can cause the aforementioned Eddy current.

More preferably, the positioning member comprises a disc-shaped body concentric to the primary stitching axis, wherein the plurality of magnets are distributed circumferentially over the disc-shaped body about said primary stitching axis. The Eddy current can thus be equally generated across the entire disc-shaped body.

In a further embodiment the plurality of magnets have alternating polarities. The alternating polarities increase the Eddy current that can be generated.

In a further embodiment the primary stitching member comprises ferromagnetic or paramagnetic material. The magnetic interaction between the magnets and the ferromagnetic material can generate sufficient Eddy current to pull along the positioning member.

In a further embodiment the primary stitching member comprises aluminum. Aluminum in itself is not a very strong magnetic material. However, when moved through the magnetic fields of the plurality of magnets, it can act as a paramagnetic material that can generate sufficient Eddy current to pull along the positioning member.

In a further embodiment the primary stitching member has a first side for mounting the stitcher to a robotic manipulator, wherein the secondary operational member is located at a second side of primary stitching member facing away from the first side. The secondary operational member can thus be located at a side of the primary stitching member that is otherwise free of components, such that it can be moved as close as possible to the circumference of the tire building drum without colliding with said tire building drum.

In a further embodiment the primary stitching member defines a cavity, wherein the positioning member is at least partially accommodated within said cavity. Hence, the positioning member does not add to the thickness or overall size of the stitcher. Consequently, the stitcher can be moved closer to the circumference of the tire building drum without colliding.

In a further embodiment the primary stitching axis and the secondary stitching axis are parallel or substantially parallel to each other. The stitching members can thus be rotated about parallel stitching axis, operating in the same or substantially the same orientation.

According to a fourth aspect, the present disclosure provides a tire building machine comprising the stitcher according to any one of the embodiments of the third aspect of the invention and a tire building drum.

The tire building machine includes the aforementioned stitcher and thus has the same technical advantages, which will not be repeated hereafter.

Preferably, the tire building drum is rotatable about a drum axis in a first rotation direction and a second rotation direction, opposite to the first rotation direction, wherein the rotation of the primary stitching member about the primary stitching axis is arranged to be driven by the rotation of the tire building drum, wherein the positioning member is rotatable about the primary stitching axis in a third rotation direction and a fourth rotation direction opposite to the third rotation direction, wherein the rotation of the positioning member about the primary stitching axis is arranged to be driven by the rotation of the primary stitching member and wherein a change in rotation of the tire building drum from the first rotation direction to the second rotation direction controls the rotation direction in which the positioning member is rotated. Hence, the rotation direction of the tire building drum can indirectly control the rotation of the positioning member, and thus the position of the secondary operational member. In particular, the rotation of the tire building drum can be reversed to move the secondary operational member into an operative stitching position. Conveniently, no dedicated control or drive means are required at the stitcher to move the secondary operational member.

According to a fifth aspect, the present disclosure provides a method for stitching a tire component with the use of a stitcher according to any one of the embodiments of the third aspect of the invention, wherein the method comprises the steps of:.

The method relates to the practical implementation of the aforementioned stitcher and thus has the same technical advantages, which will not be repeated hereafter.

In one embodiment the secondary operational member is a secondary stitching member, wherein the method further comprises the step of:.

In a further embodiment of the method the rotation of the positioning member about the primary stitching axis is driven by the rotation of the primary stitching member.

In a further embodiment the rotation of the positioning member is limited between a standby position and the active position.

In a further embodiment the rotation of the positioning member is limited between the standby position and the active position to a range of less than one-hundred-and-eighty degrees.

In a further embodiment the positioning member is rotated in the same direction about the primary stitching axis as the primary stitching member.

In a further embodiment the rotation of the positioning member is driven by Eddy current generated between said positioning member and the primary stitching member.

According to a sixth aspect, the present disclosure provides stitcher for stitching a tire component, wherein the stitcher comprises a hub that is rotatable about a stitcher axis and a plurality of stitching segments connected to, distributed around and extending radially away from the hub, wherein the stitching segments are resiliently flexible with respect to said hub.

The stitching segments can provide a segmented circumference which can effectively adapt to the shape of the tire component to be stitched.

Preferably, at least two directly adjacent stitching segments of the plurality of stitching segments are mutually coupled in a circumferential direction about the stitcher axis. By having the stitching segments influence each other's flexing to some extent, the shape of the stitcher is deformed more gradually, i.e. without abrupt steps between the stitching segments.

The various aspects and features described and shown in the specification can be applied within the scope of claims.

<FIG> show a tire building machine <NUM> for building a green or unvulcanized tire <NUM> according to an first exemplary embodiment of the invention.

The tire building machine <NUM> comprises a tire building drum <NUM> for forming the green tire <NUM>. The green tire <NUM> is formed by shaping one or more plies <NUM>, in particular body plies or breaker plies, around a bead <NUM> into a tire carcass. The bead <NUM> is an annular or substantially annular element that has a radially inner side <NUM> that defines an inner bead radius B. The green tire <NUM> is further provided with a side wall <NUM> that, in this example, is applied to the carcass by folding it, at least partially, around the radially inner side <NUM> of the bead <NUM>. In particular, the inner edge or inner tip <NUM> of the side wall <NUM> is folded around the radially inner side <NUM> of the bead <NUM>.

The tire building drum <NUM> is rotatable about a drum axis D extending in an axial direction A. The tire building drum <NUM> comprises a first drum half <NUM>, a second drum half <NUM> and a center section <NUM> in the axial direction A between said drum halves <NUM>, <NUM>.

Each drum half <NUM>, <NUM> comprises a bead-lock section <NUM>, <NUM> for retaining the bead <NUM>. The bead-lock section <NUM>, <NUM> is provided with a plurality of bead-lock segments <NUM>, <NUM> which are expandable in a radial direction R perpendicular to the drum axis D to engage and retain the bead <NUM> at the inner bead radius B. The plurality of bead-lock segments <NUM> are retractable or contractable in to a flush or recessed position relative to the rest of the tire building drum <NUM> to allow fitting of the one or more plies <NUM> and the beads <NUM> onto the tire building drum <NUM> and to provide sufficient space for folding of the side wall <NUM> around the radially inner side <NUM> of said beads <NUM>.

Each drum half <NUM>, <NUM> further comprises a turn-up section <NUM>, <NUM> for folding up the parts of the one or more plies <NUM> located outside of the center section <NUM> around the bead <NUM> onto the parts of the one or more plies <NUM> at said center section <NUM>. In particular, the turn-up sections <NUM>, <NUM> are provided with turn-up arms (not shown).

The center section <NUM> comprises a plurality of crown segments <NUM> which are expandable in the radial direction to crown-up the parts of the one or more plies <NUM> at the center section <NUM> into a toroidal or substantially toroidal shape.

As shown in <FIG>, the tire building machine <NUM> further comprises a stitcher <NUM> and a further stitcher <NUM>' at a first side and a second side, respectively, of the center section <NUM>, for stitching the side walls <NUM> to the crowned-up parts of the one or more plies <NUM> at the center section <NUM>. Each stitcher <NUM>, <NUM>' is mounted on a robotic manipulator <NUM> that controls the orientation of the respective stitcher <NUM>, <NUM>' as a whole relative to the tire building drum <NUM>. The tire building drum <NUM> is rotated about the drum axis D to cause a relative movement between the one or more plies <NUM> and the side walls <NUM> supported thereon and the stitchers <NUM>, <NUM>'. The stitchers <NUM>, <NUM>' are identical or of similar structure, except for that they are mirrored about the center section <NUM> and/or operate mirror symmetrically. The stitchers <NUM>, <NUM>' are moved on opposite sides of the center section <NUM> along respective stitcher paths P. In particular, the stitchers <NUM>, <NUM>' are moved along a first part P1 of the stitcher path P, as shown in <FIG> and <FIG>, and a second part P2 of the stitcher path P, as shown in <FIG>. Hereafter, only the stitcher <NUM> shown at the side of the second drum half <NUM> will be described in more detail. The description however applies, mutatis mutandis, to the further stitcher <NUM>'.

As best seen in <FIG> the stitcher <NUM> comprises a primary stitching shaft <NUM> that defines a primary stitching axis S1. The stitcher <NUM> comprises a primary stitching member <NUM> that is concentrically mounted to said primary stitching shaft <NUM>. In other words, the primary stitching member <NUM> is concentric to the primary stitching axis S1. The primary stitching member <NUM> is rotatable about the primary stitching shaft <NUM> and/or the primary stitching axis S1 for stitching the side wall <NUM>. Bearings <NUM> are provided to facilitate rotation of the primary stitching member <NUM> about said primary stitching shaft <NUM>. Alternatively, the primary stitching shaft <NUM> may be fixed to the primary stitching member <NUM>, provided that the primary stitching shaft <NUM> can rotate relative to the manipulator <NUM>.

The primary stitching member <NUM> comprises a stitching body that has a first side M that defines a stitching surface <NUM> for pressing against the side wall <NUM>. The stitching body is preferably disc-shaped, wheel-shaped or roller-shaped. The stitching surface <NUM> is rounded or convex near the circumferential edge or contour of the primary stitching member <NUM> for pressing both in a radial direction R perpendicular to the primary stitching axis S1 and a direction oblique to said radial direction R. The stitching body further has a mounting head <NUM> at the first side M for mounting the primary stitching member <NUM> onto the primary stitching shaft <NUM>.

The stitching body of the primary stitching member <NUM> may comprise ferromagnetic or paramagnetic material, such as aluminum.

The primary stitching member <NUM> further has a second side N facing away from the first side M. At the second side N, the primary stitching member <NUM> is provided with a cavity <NUM>. The primary stitching shaft <NUM> extends through the primary stitching member <NUM> into the cavity <NUM>.

The stitcher <NUM> is provided with a secondary operational member <NUM>. In this example, the secondary operational member <NUM> is a secondary stitching member <NUM> that is concentrically mounted to a secondary stitching axis <NUM> defined by the stitcher <NUM>. In other words, the secondary stitching member <NUM> is concentric to the secondary stitching axis S2. The secondary stitching member <NUM>, like the primary stitching member <NUM>, also comprises a disc-shaped, wheel-shaped or roller-shaped stitching body. However, the stitching body of the secondary stitching member <NUM> is a lot smaller than the stitching body of the primary stitching member <NUM>, preferably at least a factor two or three smaller. The secondary stitching member <NUM> is rotatable about the secondary stitching shaft <NUM> and/or the secondary stitching axis S2 for stitching side wall <NUM> along the radially inner side <NUM> of the bead <NUM>. The secondary stitching member <NUM> is located at the second side N of primary stitching member <NUM>.

Alternatively, the secondary operational member <NUM> may have a function different from stitching, for example cutting, brushing, pulling, tagging or detecting. The secondary operational member <NUM> may for example be a brush or a sensor.

The description hereafter is directed to the secondary stitching member <NUM>, but the same features can be applied mutatis mutandis to the alternative secondary operational members described above.

The stitcher <NUM> further comprises a positioning member <NUM> for moving the secondary stitching axis S2 relative to the primary stitching axis S2 into a stitch position or an active position, as shown in <FIG>, in which the secondary stitching member <NUM> partially projects beyond the primary stitching member <NUM> in the radial direction R. In particular, the secondary stitching member <NUM> projects beyond the circumferential edge and/or contour of the primary stitching member <NUM> in said stitching position. As such, the secondary stitching member <NUM> can reach into the relatively small gap between the radially inner side <NUM> of the bead <NUM> and the bead-lock segments <NUM>, <NUM> of the tire building drum <NUM>.

As best seen in <FIG>, the secondary stitching member <NUM>, in the stitch position, is located slightly off center with respect to the drum axis D. In particular, the secondary stitching member <NUM> is offset with respect to the drum axis D such that the secondary stitching axis S2 does not intersect with said drum axis D. This ensures that only the part of the circumference of the secondary stitching member <NUM> that rotates towards and/or into the small gap between the radially inner side <NUM> of the bead <NUM> and the bead-lock segments <NUM>, <NUM> of the tire building drum <NUM> contacts the bead <NUM>, whereas the part of the circumference of the secondary stitching member <NUM> that is rotating away from and/or out of said small gap remains free from and/or does not come into contact with said bead <NUM>. This avoids forces between the bead <NUM> and the secondary stitching member <NUM> that could potentially counteract each other.

The positioning member <NUM> is rotatable about the primary stitching shaft <NUM> and/or the primary stitching axis S1. The positioning member <NUM> may be mounted directly onto the primary stitching shaft <NUM>, for example with bearings <NUM> as shown in <FIG>, or it may alternatively be carried by suitably shaped edges or guides provided in the cavity <NUM> of the primary stitching member <NUM> so as to be rotatable about the primary stitching axis S1.

In another embodiment (not shown), an alternative positioning member may be provided which displaces the secondary stitching member <NUM> linearly, for example in the radial direction R to move said secondary stitching member <NUM> between a standby position fully inside the circumference of the primary stitching member <NUM> and a stitching position at least partially projecting beyond the circumference of said primary stitching member <NUM>.

The secondary stitching shaft <NUM> is coupled to, connected to or carried by the positioning member <NUM> in a position spaced apart from the primary stitching shaft <NUM>. In other words, the primary stitching axis S1 and the secondary stitching axis S2 are spaced apart from each other. In said spaced apart position, the secondary stitching member <NUM>, which is a lot smaller than the primary stitching member <NUM>, can be considered as a planetary satellite member to the primary stitching member <NUM>, almost as if it is travelling along an orbit defined by the edge of the primary stitching member <NUM>. The positioning member <NUM> is configured for holding the secondary stitching shaft <NUM> in an orientation parallel or substantially parallel to the primary stitching shaft <NUM>. In other words, the primary stitching axis S1 and the secondary stitching axis S2 are parallel or substantially parallel to each other.

As best seen in <FIG>, the positioning member <NUM> is disc-shaped or has a disc-shaped body <NUM>. In particular, the positioning member <NUM> is provided with a plurality of magnets <NUM> distributed evenly and/or circumferentially over the disc-shaped body <NUM> about said primary stitching axis S1. In this example, the plurality of magnets <NUM> have alternating polarities.

The positioning member <NUM> is further provided with a first limiter <NUM> and/or a second limiter <NUM> for limiting the rotation of the positioning member <NUM> about the primary stitching shaft <NUM> and/or the primary stitching axis S1 to a range of less than one-hundred-and-eighty degrees, preferably less than one-hundred degrees. In this exemplary embodiment, the first limiter <NUM> and the second limiter <NUM> are defined or formed by the terminal ends of an angular slot that interacts with a pin of the primary stitching member <NUM>. Alternatively, the limiters <NUM>, <NUM> may be formed by any suitably placed obstacle provided on one of the primary stitching member <NUM>, the primary stitching shaft <NUM>, the positioning member <NUM> and/or the secondary stitching member <NUM> and interacting with another one of the primary stitching member <NUM>, the primary stitching shaft <NUM>, the positioning member <NUM> and the secondary stitching member <NUM>.

A method for stitching the side wall <NUM> with the use of the aforementioned stitcher <NUM> will now be briefly elucidated with reference to <FIG>.

<FIG> and <FIG> show the situation at the start of a primary stitching operation, with the secondary stitching member <NUM> in a standby position in which the secondary stitching member <NUM> is spaced apart from and does not interact with and/or press onto the side wall <NUM>. The manipulator <NUM> has positioned the primary stitching member <NUM> at the start of the first part P1 of the stitching path P, in an orientation relative to the side wall <NUM> such that the radially outer parts of said side wall <NUM> can be pressed and/or stitched onto the one or more plies <NUM> underneath. <FIG> shows the situation after the manipulator <NUM> has moved the primary stitching member <NUM> further along and towards the end of the first part P1 of the stitching path P. The secondary stitching member <NUM> is still held in the standby position. <FIG> and <FIG> show the situation at the start of a secondary stitching operation, when the secondary stitching member <NUM> is moved relative to the primary stitching shaft <NUM> and/or the primary stitching axis S1 from the standby position into the stitching position. As best seen in <FIG>, the stitcher <NUM> can now be moved by the manipulator <NUM> such that the secondary stitching member <NUM> follows, presses and folds the side wall <NUM> around the radially inner side <NUM> of the bead <NUM>, without colliding with the bead-lock segments <NUM>, <NUM> underneath.

In this exemplary embodiment, the positioning member <NUM> is not directly driven or controlled by any dedicated drive means. Instead, the rotation of the primary stitching member <NUM> is transferred onto the positioning member <NUM>. In particular, the positioning member <NUM> is configured for rotating in the same direction about the primary stitching axis S1 as the primary stitching member <NUM>. In other words, the positioning member <NUM> is configured to passively follow the rotation of the primary stitching member <NUM>. In this example, the transfer of rotation is achieved by generating Eddy current as the primary stitching member <NUM> is rotated relative to the plurality of magnets <NUM> of the positioning member <NUM>. The positioning member <NUM> is freely rotatable. Hence, it will tend to be pulled along by the primary stitching member <NUM>. As such, the positioning member <NUM> can be driven by the rotation of the primary stitching member <NUM>, within the range defined by the limiters <NUM>, <NUM>, to move the secondary stitching member <NUM> from the standby position, as shown in <FIG>, to the stitching position, as shown in <FIG>.

Alternatively, the rotation of the primary stitching member <NUM> can be transferred onto the positioning member <NUM> via other transmission means, in particular a mechanical transmission. For example, a mechanical friction may be provided between the primary stitching shaft <NUM> and the positioning member <NUM>. In another example, the centrifugal forces generated by the rotation of the primary stitching member <NUM> can be used to activate a centrifugal clutch or coupling.

Similarly, the primary stitching member <NUM> is not directly driven or controlled by any dedicated drive means. Instead, the rotation of the tire building drum <NUM> is transferred onto the primary stitching member <NUM> when the primary stitching member <NUM> is brought into contact with the tire building drum <NUM> or the one or more plies <NUM> and/or the side wall <NUM> supported on said tire building drum <NUM>. In other words, the primary stitching member <NUM> is configured to be passively driven by the tire building drum <NUM>. In particular, the direction of rotation of the tire building drum <NUM> determines the direction of rotation of the primary stitching member <NUM>. And because the positioning member <NUM> passively follows the rotation of the primary stitching member <NUM>, it can be said that the tire building drum <NUM> indirectly drives and/or controls the rotation of the positioning member <NUM> about the primary stitching shaft <NUM> and/or the primary stitching axis S1.

This principle can be used to move the positioning member <NUM> between the standby position of <FIG> and the stitching position of <FIG>. In particular, when the tire building drum <NUM> is rotated in a first rotation direction R1 about the drum axis D, as shown in <FIG>, the primary stitching member <NUM> of the stitcher <NUM> rotates in a third rotation direction R3 which causes the positioning member <NUM> to rotate in the same third rotation direction R3, moving the secondary stitching member <NUM> away from the stitching position and into the standby position. When the secondary stitching member <NUM> is to be moved into the stitching position, the rotation direction of the tire building drum <NUM> is reversed, as shown in <FIG>, to a second rotation direction R2 opposite to the first rotation direction R1, thereby causing the primary stitching member <NUM> to reverse its rotation direction to a fourth rotation direction R4 opposite to the third rotation direction R3. This causes the positioning member <NUM> to move in the same fourth rotation direction R4, moving the secondary stitching member <NUM> to the stitching position.

The brief moment of stopping and reversing the rotation direction of the tire building drum <NUM> can conveniently be used to terminate the primary stitching operation of the primary stitching member <NUM> along the first part P1 of the stitching path P and reposition the stitcher <NUM>, if necessary, to be optimally positioned for the secondary stitching operation which involves folding the side wall <NUM> around the radially inner side <NUM> of the bead <NUM>.

It will be apparent to one skilled in the art that the primary stitching member <NUM> and/or the secondary stitching member <NUM> can be driven directly and/or individually by a suitable drive means, such as a servo motor. Additionally or alternatively, other means of transferring rotation between the primary stitching member <NUM> and the positioning member <NUM> may be provided, for example mechanical transfer means such as gears or the like.

<FIG> shows an alternative tire building machine <NUM> that differs from the aforementioned tire building machine <NUM> in that its stitcher <NUM> comprises a disc-shaped stitching body <NUM> having a first side <NUM> and a second side <NUM> opposite to the first side <NUM>. The second side <NUM> is concave. Because of the concave side, the stitcher <NUM> can be moved closer to the circumference of the tire building drum <NUM> without colliding.

The disc-shaped stitching body <NUM> is concentric about a stitching axis S. The first side <NUM> defines a pressing surface <NUM> that is arranged at a slope or an inclination that is inclined away from the second side <NUM> at a clearance angle H in a radial direction R away from the stitching axis S. The clearance angle H is in a range of zero to fifteen degrees, preferably in a range of one to fifteen degrees, more preferably in a range of two to ten degrees, more preferably in a range of four to six degrees and most preferably approximately five degrees.

As shown in <FIG>, the bead-lock segments <NUM> which are retracted into the recessed position relative to the rest of the tire building drum <NUM>. The recess at the bead-lock segments <NUM> defines a transition T or transition edge between the retracted bead-lock segments <NUM> and the rest of the tire building drum <NUM>. The stitcher <NUM> is positionable relative to the tire building drum <NUM>, for example with the use of the manipulator <NUM> shown in <FIG>, such that the concave second side <NUM> fits at least partially over said transition T. In other words, the transition T is at least partially received in the cavity defined by the second side <NUM>. More in particular, the stitcher <NUM> is positioned relative to the tire building drum <NUM> such that the stitching axis S is at an oblique angle to a vertical plane. In this orientation, the stitcher <NUM> can be dipped or scooped underneath the radially inner side <NUM> of the bead <NUM> to reach into the limited space between said radially inner side <NUM> and the recessed bead-lock segments <NUM>. The oblique orientation of the stitcher <NUM> also tilts at least a part of the pressing surface <NUM> towards or into a horizontal plane for securely pressing against the inner tip <NUM> of the side wall <NUM>.

The stitcher <NUM> of the alternative tire building machine <NUM>, in its stitch position, may be located or offset slightly off center with respect to the drum axis D, in a similar way to the secondary stitching member <NUM> in <FIG>, such that its stitching axis S does not intersect with said drum axis D. In this way, one part of its circumference is kept in contact with the bead <NUM>, whereas the other part remains free from and/or does not come into contact with said bead <NUM>.

<FIG> show a further alternative tire building machine <NUM> according to a third embodiment of the present invention. The alternative tire building machine <NUM> differs from the previously discussed tire building machines <NUM>, <NUM> in that the further alternative tire building machine <NUM> comprises an alternative stitcher <NUM> having an alternative stitching body <NUM>. The alternative stitching body <NUM> is rotatable about the stitcher axis S. As can best be seen in <FIG>, the alternative stitching body <NUM> comprises a hub <NUM> and a plurality of stitching segments <NUM> circumferentially distributed about the stitcher axis S. The stitching segments are connected to and extending from the hub <NUM> in the radial stitcher direction P2. The stitching segments <NUM> are resilient with respect to the hub <NUM> in the axial stitcher direction A2. In other words, a terminal end of each stitching segment <NUM> is resiliently movable back and forth in the axial stitcher direction A2. The alternative stitching body <NUM> is flat or substantially flat and/or shaped like a disk. The hub <NUM> has a relatively low height in the axial stitcher direction A2 compared to the previously discussed stitching body <NUM>. Hence, the alternative stitching body <NUM> can be more easily interposed between the bead <NUM> and the bead-lock segments <NUM>, <NUM>. In this exemplary embodiment, the stitching segments <NUM> each comprise at their respective terminal end a pressing portion <NUM> for pressing the side wall <NUM> against the radial inner side <NUM> of the bead <NUM>. The pressing portion <NUM> bulges from the stitching segments <NUM> in the axial stitcher direction A2.

Optionally, as is best shown in <FIG>, the stitching segments <NUM> are mutually coupled in a circumferential stitcher direction about the stitcher axis S. Due to the mutual coupling, a displacement in the axial stitcher direction A2 of the terminal end of one of the stitching segments affects the displacement of adjacent and/or proximate stitching segments <NUM>. In other words, when one of the stitching segments <NUM> is displaced in the axial stitcher direction A2, the adjacent and/or proximate stitching segments are displaced as well. Each stitching segment <NUM> comprises a first profile section <NUM> and a second profile section <NUM> which is complementary to the first profile section <NUM>. Preferably, the alternative stitching body <NUM> is manufactured by 3D-printing.

Claim 1:
Tire building machine comprising a tire building drum and a stitcher (<NUM>) for stitching a tire component, wherein the tire building drum (<NUM>) comprises bead-lock segments (<NUM>) which are retractable into a recessed position relative to the rest of the tire building drum, wherein the stitcher comprises a disc-shaped stitching body (<NUM>) having a first side (<NUM>) for pressing on the tire component during stitching and a second side (<NUM>) opposite to the first side,
characterized in that
the second side is concave, wherein the stitcher is positionable relative to the tire building drum (<NUM>) such that the concave second side (<NUM>) fits at least partially over a transition between the bead-lock segments (<NUM>) in the recessed position and the rest of the tire building drum.