Curing mold and method for curing green tires

Abstract

The present invention relates to a curing mold (10) for a tire, comprising: an upper shell (16a) for molding the sidewall of the tire; a lower shell (16b) for molding the sidewall of the tire; and a crown ring (20) consisting of circumferential segments for molding the tread of the tire, each segment comprising an upper segment part (20a) that can be axially separated from a lower segment part (20b). The curing mold (10) is capable of interacting with means for simultaneously moving all segment parts radially. Each lower segment part (20b) is provided with a holding device (100) for holding the lower segment part (20b) in a radial position between the closed and open positions of the mold, and the elements of the holding device (100) belong to the lower segment part and the lower shell (16b).

Description

Technical Field

[0001] The present invention relates to the manufacture of tires, and more particularly to molds and methods for curing or vulcanizing green tires. More particularly, it relates to the manufacture of tires having a tread pattern extending on the sidewall, such as those used on all-terrain (or off-road) vehicles.

Background Art

[0002] The manufacture of tires includes a curing step of vulcanizing and molding a green tire blank to obtain a tire having desired mechanical properties, geometry, and appearance. Curing is performed in a tire curing mold having upper and lower molding assemblies that are axially movable relative to each other. The molding assemblies include molding elements that together define an internal tire molding surface. The mold mainly includes two shells for molding the sidewalls of the tire and two rings for molding the beads of the tire, located on both axial sides of a crown ring having a plurality of circumferential segments for molding the tread of the tire. Such a curing mold is disposed in a curing press machine having a mechanism that enables, in particular, opening and closing of the curing mold on the green tire and releasing the curing mold to remove the vulcanized tire and insert a new green tire.

[0003] International Publication No. WO 2014 / 044713 of the present applicant describes a curing mold for such a tire mainly comprising an upper shell for molding a sidewall of a tire, which is movable together with an upper plate of a press, and a lower shell for molding a sidewall of a tire, which is fixed and held by a lower plate of the press. Further, the mold comprises a crown ring composed of circumferential segments for molding a tread of the tire, and the crown ring is movable radially between an open position and a closed position of the mold. Each segment is connected to the upper plate of the press, and the upper shell is fixed to the upper plate, and the upper shell is axially movable together with the upper plate and is also radially movable with respect to the upper plate. Accordingly, each segment is slidable radially with respect to the upper shell and is slidable axially and radially with respect to the lower shell. Although this mold functions well, it has been observed that it is not suitable for molding a tire in which a tread pattern of the tread extends onto the sidewall because the radial retraction of such mold segments is not sufficient to remove the vulcanized tire.

[0004] Furthermore, Korean Patent Application Publication No. 20140018710(A) discloses a curing mold in which the mechanism is similar to the mechanism described in the above-mentioned document, but in order to facilitate the insertion of the green tire before curing and the removal of the cured tire, a crown ring composed of circumferential segments is divided into two parts, an upper part and a lower part, by a horizontal plane passing through the meridian of the tire. The segments of the two crown rings are such that when the actuator translates the upper shell axially, they retract radially, but only the upper crown ring is lifted together with the upper shell, and the segments of the lower crown ring remain in contact with the lower shell. Guide fingers protruding from the radial interface surface of each upper segment at the open position of the mold interact with holes in the opposing lower segments when the mold is closed. The guide fingers push in spring-mounted rods located within the opposing lower segments, and these rods are provided to guide the radial translation of the lower segments. This enables a greater radial retraction than the segments of the above-mentioned document, but it is necessary to modify the curing press, more specifically its lower plate, or the tool for operating the mold so that they can accept the mold according to the above-mentioned document. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] There remains a need to be able to use the same curing press and the same tool for operating the mold without modification for different types of tires with different tread patterns, and thus to be able to accept different curing molds. MEANS FOR SOLVING THE PROBLEMS

[0006] One object of the present invention is to overcome the drawbacks of the above-mentioned document and thus facilitate the molding and demolding of a tire in which the tread pattern of the tread extends onto the sidewall. Another object of the present invention is to improve the appearance of the molded tire.

[0007] This object is achieved by the present invention, which proposes a curing mold for a tire as follows: - an upper shell for molding the sidewall of the tire, - a lower shell for molding the sidewall of the tire, - a crown ring consisting of circumferential segments for molding the tread of the tire, each segment comprising an upper segment part suitable for being axially separated from a lower segment part, a curing mold for a tire, comprising - suitable for interacting with means for simultaneously moving all segment parts radially and moving the upper part of each segment axially relative to the lower part of the same segment during the opening and closing operations of the mold, each lower segment part is provided with a device for holding the lower segment part in a radial position between the closed and open positions of the mold, and the elements of the holding device are characterized by belonging to the lower segment part and the lower shell.

[0008] The curing mold of the present invention comprises a crown ring consisting of circumferential segments that form a closing ring in the closed position of the mold. The crown ring consisting of circumferential segments is cut along a radial horizontal plane so that the upper and lower parts of the segments of the crown ring can be axially and circumferentially separated from each other during the opening of the mold. As a result, the opening of the molding cavity can now be enlarged, facilitating the removal of a tire in which the tread pattern of the tread extends onto the sidewall.

[0009] The present invention proposes a device created to be able to hold the lower part of each segment in a predetermined radial position in order to suppress the risk related to the relative movement between the upper and lower parts of the segment during the movement for opening and closing the mold. Additionally, a device for holding such a lower segment part prevents accidental displacements (for example, falling objects, actions by operators inside the press) that can occur when the mold is open. Thus, the lower segment part is held in a predetermined position in the radial direction and can interact correctly with the upper segment part during the movement for opening and closing the mold. Holding the lower segment part in a predetermined position means that the lower segment part is held in the stable position it maintains unless a predetermined force is applied to make the lower segment part move away from this holding position.

[0010] Also, according to the present invention, since all the elements of the holding device belong to the lower segment part and the lower shell, the mold of the present invention can also be incorporated into any suitable press without making any changes to its elements, for example, its plates.

[0011] Furthermore, since the holding device is connected to each lower segment part, this solution can be applied to any type of mold regardless of the number of segments of the mold or their positioning.

[0012] The holding device can be manufactured so as to be able to hold the lower segment part in a predetermined axial position. Thereby, for example, when the mold is opened to remove the cured tire and the tire has a tendency to stick to the wall of the cured mold, in order to ensure the good operation of the mold without damaging the tire, it is possible to hold the lower segment part in a stable axial position as well as in a stable radial position.

[0013] This holding device can comprise a radially extending slider which interacts with a pusher manufactured to exert a radial force on the slider while the lower segment part moves radially between the open and closed positions of the die. Thus, according to the invention, further, the pusher which exerts an axial force in the direction of the slider can also hold the lower segment part in a stable axial position at two end positions, namely a first radially inner position when the die is closed and a second radially outer position when the die is open.

[0014] In a first embodiment of the invention, the slider can be movable together with the lower segment part and the pusher can be fixed on the lower shell by a bottom plate.

[0015] The slider can comprise rollers which can interact with two notches arranged on both sides of the pusher within the bottom plate during the radial movement of the lower segment part.

[0016] In a second embodiment of the invention, the slider can be fixed on the lower shell and the pusher can be movable together with the lower segment part.

[0017] The slider can comprise two notches which can interact with the balls of the pusher during the radial movement of the lower segment part.

[0018] The pusher can comprise a return spring.

[0019] The return spring can be calibrated to hold the lower segment part in a predetermined position when the force applied to the pusher is smaller than the force received when the die is closed.

[0020] The slider can have a double-tail cross-section. This double-tail shape can guide the radial translation of the lower segment part well and hold it in a predetermined axial position, especially in the case of an adhesive composition or a tire with a complex tread pattern that tends to adhere to the inner wall of the mold's molded parts.

[0021] Furthermore, the present invention relates to - an upper shell for molding the sidewall of a tire, - a lower shell for molding the sidewall of a tire, - a crown ring composed of circumferential segments for molding the tread of a tire, each segment comprising an upper segment part suitable for being axially separated from the lower segment part, and relates to a method for molding a tire using a mold comprising This mold is - suitable for interacting with means for simultaneously moving all the segment parts radially during the opening and closing operations of the mold and moving the upper part of each segment axially relative to the lower part of the same segment, The method comprises simultaneously moving all the segments radially outward and moving the upper part of each segment axially upward, in the case where the lower part of the segment is switched from a first radially inner holding position to a second radially outer holding position, and including the step of removing the tire at the end of curing.

[0022] The molding method of the present invention can include the step of closing an empty mold and subsequently opening the mold without retracting the segments radially to insert a new green tire into the mold.

[0023] The molding method of the present invention can include the step of closing the mold only axially on the green tire inserted into the mold.

[0024] The present invention can be better understood from the remaining part of this specification based on the following figures.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0026] In various figures, the same or similar elements are given the same reference numerals. Therefore, their descriptions will not be repeated in order.

[0027] FIG. 1 shows a mold 10 for curing a green tire according to a first embodiment of the present invention. This curing mold 10 is intended to be inserted between the upper plate 2 and the lower plate 4 of the curing press 1. The curing press is provided with a frame forming the base of the mold and is assumed to be stationary and fixed to the ground. The press is also provided with means (e.g., a hydraulic cylinder) for guiding and operating the mechanism for opening and closing the mold, and equipment enabling the application of the curing conditions (pressure and temperature of the heat transfer fluid) necessary for vulcanizing the tire to the mold.

[0028] The mold 10 for curing a green tire includes an upper mold assembly and a lower mold assembly. Each mold assembly includes an upper shell 16a and a lower shell 16b for forming the sidewall of the tire, an upper ring 18a and a lower ring 18b for forming the bead of the tire, and a crown ring 20 composed of circumferential segments for forming the tread of the tire. In the illustrated example, the mold is of the "container" type. In this case, the upper shell 16a slides axially together with the upper plate 2 of the press, the lower shell 16b is firmly fastened to the lower plate 4 of the press, and the circumferential segments move radially when the mold is opened and closed.

[0029] The curing mold 10 exhibits rotational symmetry substantially with respect to the central axis X-X'. The central axis extends in the vertical direction. In the remainder of this specification, "axial" or "axially" refers to a direction or movement parallel to the central axis, and "radial" or "radially" refers to a direction or movement perpendicular to the central axis X-X'. The circumferential direction is the direction in contact with the radial direction and corresponds to the circumferential direction of the tire.

[0030] The circumferential segments of the crown ring 20 are arranged side by side circumferentially, and each segment of the crown ring is preferably divided into two upper and lower parts by a radial plane which is the median plane M in the illustrated example, i.e., a plane passing equidistant from the bead of the tire and thus equidistant from the forming rings 18a, 18b. More specifically, as will be described below, each segment comprises an upper segment part 20a and a lower segment part 20b, and the upper 20a and lower 20b parts are located on both sides of the plane M, contact each other when the mold is closed, and are spaced apart from each other when the mold is opened. Each segment part comprises a lining for forming the tread pattern of the tire held by the segment support. Thus, the upper segment part 20a comprises a lining 19a extending from the interface with the lower part 20b to the interface with the upper shell 16a. Similarly, the lower segment part 20b comprises a lining 19b extending from the interface with the upper part 20a to the interface with the lower shell 16b. As can be seen from FIG. 1, the linings 19a, 19b extend beyond the tread and are intended to form a tire in which the tread pattern of the tread extends onto the sidewall.

[0031] The radially outer surfaces 21a, 21b of the lining supports of the upper segment part 20a and the lower segment part 20b are conical and have the same inclination extending downwardly and radially outwardly.

[0032] The press further comprises a conical ring 14, the inner radial surface 14a of which is inclined downward in the radial direction and has the same inclination as the outer radial surfaces 21a and 21b. The conical ring is connected to an actuator of the curing press, such as a hydraulic cylinder, and can thus move axially upward and downward. During the closing of the mold, the conical ring 14 moves downward and is positioned on the crown ring 20 of the segment, moving the segment radially inward of the mold and applying a force to the segment to keep the assembly in a closed state when the temperature in the molding cavity rises during curing. The conical ring 14 comprises a plurality of sliders 12, each firmly fastened to the conical ring, and each slider is intended to slide within the rails of the corresponding segment of the crown ring 20. A stop located between one end of the slider 12 and the notch in the outer surface 21a of each segment makes it possible to limit the radial retraction stroke of the segment while the conical ring moves upward to open the mold. In this embodiment, the conical ring 14, the sliders 12, and the elements for connecting them to the segments of the mold and to the upper plate of the press are as described in International Publication No. 2014 / 044713.

[0033] The upper plate 2 of the press is connected to another actuator, such as a hydraulic cylinder, which allows axial movement upward and downward during the operation of opening and closing the mold, as will be described below.

[0034] In the open position of the mold, the conical ring 14 and the upper molding parts firmly connected to the upper plate 2 of the press, namely the upper segment part 20a, the upper shell 16a, and the upper molding ring 18a, move axially upward to empty the molding cavity and allow the removal of the cured tire and the insertion of a new green tire. During the closing of the mold, the upper plate moves downward, the upper segment part 20a retracts radially outward, and the conical ring 14 moves downward to close the curing cavity and thus the mold for curing. The heat transfer fluid reaches the mold cavity from a device 25 located in the central part of the curing cavity, which comprises, for example, a curing bladder that presses the green tire against the inner parts of the mold during curing.

[0035] According to the present invention, each lower segment part 20b is provided with a device 100 for holding the lower segment part 20b at a radial position between the closed position and the open position of the mold.

[0036] In a first embodiment, most clearly seen in FIGS. 1, 2a and 2b, the elements of the holding device 100 belong to the lower segment part 20b and the lower shell 16b. More specifically, the holding device 100 comprises a slider 101 having an elongated shape extending in the radial direction and adapted to move within a cavity 102 made in the base of the lower segment part 20b, which slider interacts with a pusher 108 arranged within the bottom plate 110 of the lower shell 16b. The slider 101 is rigid and has the shape of an elongated beam extending between the lower shell 16b and the lower segment part 20b and has, for example, a double-tail cross-section. In another embodiment (not shown), the cross-section of the slider is T-shaped or has some suitable shape, and at the same time, the slider guides the radial translation of the lower segment part and can prevent its axial movement when subjected to a force having an axial component. The bottom plate 110 is firmly fastened to the lower shell 16b, for example, using fastening screws. More specifically, the bottom plate 110 comprises a hole 107 in which the pusher 108 and a return spring 109 that axially outwardly pushes the pusher are arranged, and the substantially rounded axial lower end 108' of the pusher 108 projects with respect to the end of the bottom plate 110. The axial lower surface 110' of the bottom plate 110 comprises two cavities 112 and 114 located on both sides of the pusher 108. The slider 101 comprises a roller 105 mounted so as to be freely rotatable about its central axis, which roller is located at the axial outer end of the slider and interacts with the notches 112 and 114 during the radial movement of the lower segment part 20b. The bottom plate 110 further comprises a stopper 115 for stably positioning the roller in the notch 114. The slider 101 is firmly connected to the lower segment part 20b and is fastened thereto by a pin 116 inserted into a hole 117 having an axis transverse to the longitudinal direction of the slider 101 and the lower segment part 20b and a fastening screw (not shown) transverse to the axis of the hole 117.

[0037] During operation, the roller 105 of the slider 101 is positioned within the notch 112 when the mold is in the closed position. When the mold is opened, the lower segment part 20b moves radially outward, and the roller 105 of the slider 110 follows the movement of the segment, actuating the pusher 108 against the return spring 109. At the end of the radially rearward movement of the lower segment part 20b, the roller 105 reaches the second notch 114, where it is held by the protrusion 108' of the pusher 108. The pusher returns to its original position under the action of the spring 109 and is held by the stopper 115.

[0038] The slider 110 takes two stable positions when moving: the first position corresponding to the closed position of the mold when the roller 105 is positioned in the notch 112, and the second position corresponding to the open position of the mold when the roller 105 is received in the notch 114 of the bottom plate 110 under the latching effect of the pusher 108. This can hold the lower segment part 20b in a predetermined axial and radial position and prevent it from moving in the open position of the mold.

[0039] Here, the operation of the mold according to the first embodiment will be described with reference to FIGS. 3a - 3i. FIG. 3a shows the curing mold 10 in the closed or curing position for obtaining the tire P, and the roller 105 is located in the notch 112 of the bottom plate 110. FIG. 3b shows the step at which the opening of the mold begins when an axial force is applied that causes simultaneous radial rearward movement of the upper and lower segment parts with respect to the conical ring 14. For example, a device (not shown), such as a finger protruding on the upper segment part 20a and interacting with the hole of the lower segment part 20b and the interface surface of both parts, can synchronize the upper part 20a and the lower part 20b of each segment. The roller 105 is away from the notch 112. When the radial rearward movement of the segment is performed, the upper segment part 20a is separated from the lower segment part 20b along the radial plane M.

[0040] Figure 3c shows the fully open position of the mold, at which position, since the upper molding part moves axially, the cured tire can be taken out. At this position, the roller 105 interacts with the notch 114 of the bottom plate 110 to hold the lower segment part 20b in a predetermined position.

[0041] Figures 3d and 3e show the steps of closing the empty mold. The mold is closed by lowering the upper plate 2 and the conical ring 14 axially.

[0042] Figure 3f shows the step of opening the mold, which is to open only axially (or vertically) without retracting the segments, particularly the upper segment part 20a and the lower segment part 20b, radially. The lower segment part 20b is held against the lower shell 16b by the force of the spring 109 of the pusher 108 that applies a force to the roller 105 of the slider 101. The actuator for moving the upper segment part 20a holds the upper segment part 20a against the upper shell 16a. As shown in Figure 3g, a new green tire E can be inserted into the mold cavity. Next, as shown in Figure 3h, the mold is closed only axially (or vertically), and as shown in Figure 3i, curing can be performed when the mold is fully closed.

[0043] Only by this additional step of closing the empty mold before opening axially (or vertically) can the upper segment part and the lower segment part be returned to their original radial positions before inserting the new green tire, and as a result, rubber entrapment at the interface between each of the radially outer ends of the upper part 20a and the lower part 20b and the upper shell 16a and the lower shell 16b can be prevented. Therefore, the appearance of the cured tire is improved.

[0044] In a second embodiment, most clearly seen in FIGS. 4, 5a and 5b, all elements of the holding device 100 belong to the lower segment part 20b and the lower shell 16b. More specifically, the holding device 100 comprises a slider 121 including two notches 124 and 126 that interact with a pusher 103 belonging to the lower segment part 20b. The slider 121 is firmly fastened to the lower shell 16b at its radially outer end 121' by some suitable means such as screwing (not shown), and the other end of the slider is free. The slider 121 is rigid and is in the shape of an elongated beam extending between the lower shell 16b and the lower segment part 20b, and has, for example, a double-tail cross-section. The lower segment part 20b comprises, at its base, an elongated hole 122 having a shape complementary to the shape of the slider 121; more specifically, the hole 122 has the same shape as the slider, a double-tail cross-section in the example shown, but has larger dimensions to allow the lower segment part 20b to slide radially with respect to the slider 121. The lower segment part 20b comprises a pusher 103 of the type including a ball 118 that is pushed down by a return spring 119.

[0045] During operation, the ball 118 of the pusher 103 is positioned within the notch 124 when the mold is in the closed position. When the mold is opened, the lower segment part 20b moves radially outwards, and the ball 118 of the pusher 103 follows the movement of the segment while rolling on the slider while compressing the return spring 109. At the end of the radially rearward movement of the lower segment part 20b, the ball 118 of the pusher 103 reaches the second notch 126, where it is held by the action of the extending return spring 119. A stopper 128 prevents the lower segment part 20b from moving radially beyond this position.

[0046] The lower segment part 20b takes two stable positions when moving: a first position corresponding to the closed position of the mold when the pusher 103 is positioned in the notch 124, and a second position corresponding to the open position of the mold when the pusher 103 is received in the notch 126 of the slider 120 due to the latching effect. Thereby, the lower segment part 20b can be held in a predetermined position in the axial and radial directions, preventing it from moving in the open position of the mold.

[0047] Here, the operation of the mold according to the second embodiment will be described with reference to FIGS. 7a to 7i. FIG. 7a shows the curing mold 10 in the closed position or the curing position for obtaining the tire P, and the ball 118 of the pusher 103 is located in the notch 124 of the slider 121. FIG. 7b shows the step at which the opening of the mold starts when an axial force is applied that causes the simultaneous radial retreat of the upper and lower segment parts with respect to the conical ring 14. For example, a device (not shown), such as a finger that protrudes on the upper segment part 20a and interacts at the boundary between the hole of the lower segment part 20b and the two parts, can synchronize the upper part 20a and the lower part 20b of each segment. The ball 118 of the pusher 103 is away from the notch 124. When the radial retreat of the segment is performed, the upper segment part 20a is separated from the lower segment part 20b along the radial plane M.

[0048] FIG. 7c shows the fully open position of the mold. At this position, since the upper molding part moves axially, the cured tire can be taken out. At this position, the ball 118 of the pusher 103 interacts with the notch 126 of the slider 121, holding the lower segment part 20b in a predetermined position.

[0049] FIGS. 7d and 7e show the step of closing the empty mold. The mold is closed by lowering the upper plate 2 and the conical ring 14 axially.

[0050] Figure 7f shows the step of opening the mold, where the mold is opened only in the axial direction (or vertical direction) without retracting the segments, particularly the upper segment part 20a and the lower segment part 20b, in the radial direction. The lower segment part 20b is held against the lower shell 16b by the force of the spring 119 of the pressing tool 103 that presses a ball into the notch of the slider 121. The actuator for moving the upper segment part 20a holds the upper segment part 20a against the upper shell 16a. As shown in Figure 7g, a new green tire E can be inserted into the mold cavity. Next, as shown in Figure 7h, the mold is closed only in the axial direction (or vertical direction), and curing can be performed when the mold is completely closed as shown in Figure 7i.

[0051] As described above, only by this additional step of closing the empty mold before opening it in the axial direction (or vertical direction), the upper segment part and the lower segment part can be returned to their original radial positions before inserting the new green tire. As a result, it is possible to prevent the rubber from being pinched at the interface between each of the outer radial ends of the upper part 20a and the lower part 20b and each of the upper shell 16a and the lower shell 16b. Therefore, the appearance of burrs on the cured tire can be avoided.

[0052] Other variations and embodiments of the present invention can be envisioned within the scope of the present invention as described in the claims. Therefore, the upper segment part and the lower segment part can be axially separated along a radial plane other than the median plane or along a plane that is not radial.

Explanation of Reference Numerals

[0053] 1 Curing press 2 Upper plate 4 Lower plate 10 Curing mold 12 Slider 14 Conical ring 16a Upper shell 16b Lower shell 18a Upper ring 18b Lower ring 19a Upper lining 19b Lower lining 20 Crown ring 20a Upper segment component 20b Lower segment component 21a Radial outer surface of the upper lining support part 21b Radial outer surface of the lower lining support part 25 Device for supplying heat transfer fluid into the mold cavity 100 Device for holding the lower segment component 101 Slider 103 Pusher 116 Pin M Median plane

Claims

1. A mold (10) for hardening a tire, An upper shell (16a) for forming the tire sidewall, A lower shell (16b) for shaping the tire sidewall, A crown ring (20) comprising circumferential segments for forming the tread of a tire, wherein each segment comprises an upper segment component (20a) suitable for axial separation from a lower segment component (20b), Equipped with, The aforementioned mold is During the opening and closing operation of the mold, the means for simultaneously moving all of the segment components radially and for moving the upper segment component (20a) of each segment axially relative to the lower segment component (20b) of the same segment is suitable for interaction with such means. A mold characterized in that each lower segment component (20b) is provided with a retaining device (100) for holding the lower segment component (20b) at a radial position between the closed position and the open position of the mold, and the elements of the retaining device (100) belong to the lower segment component and the lower shell (16b).

2. The mold according to claim 1, wherein the holding device is manufactured to hold the lower segment component (20b) in a predetermined axial position.

3. The mold according to claim 1 or 2, wherein the retaining device (100) comprises radially extending sliders (101, 121), the sliders interacting with presses (103, 108) manufactured to exert axial force on the sliders during radial movement of the lower segment component (20b).

4. The mold according to claim 3, wherein the slider (101) is movable together with the lower segment component (20b), and the pusher (108) is fixed on the lower shell (16b) by the bottom plate (110).

5. The mold according to claim 4, wherein the slider (101) comprises a roller (105) that interacts with two notches (112, 114) located on both sides of the pusher (108) within the bottom plate (110) during the radial movement of the lower segment component (20b).

6. The mold according to claim 3, wherein the slider (121) is fixed on the lower shell (16b) and the pusher (103) is movable together with the lower segment component (20b).

7. The mold according to claim 6, wherein the slider (121) comprises two notches (124, 126) that interact with the ball (118) of the pusher (103) during the radial movement of the lower segment component (20b).

8. The mold according to claim 3, wherein the pressing tool (103, 108) is equipped with return springs (109, 119).

9. The mold according to claim 8, wherein the return spring is calibrated so as to hold the lower segment component (20b) in a predetermined position when the force applied to the pusher (103, 108) is less than the force received when the mold is closed.

10. The mold according to claim 3, wherein the sliders (101, 121) have a dovetail-shaped cross-section.

11. An upper shell (16a) for forming the tire sidewall, A lower shell (16b) for shaping the tire sidewall, A crown ring (20) comprising circumferential segments for forming the tread of a tire, wherein each segment comprises an upper segment component (20a) suitable for axial separation from a lower segment component (20b), A molding method for molding a green tire using a hardening mold equipped with, The hardening mold is During the opening and closing operation of the hardening mold, the means for simultaneously moving all of the segment components radially and for moving the upper segment component (20a) of each segment axially relative to the lower segment component (20b) of the same segment is suitable for interaction with the means. The aforementioned method, A molding method comprising the step of removing the tire when curing is complete, in which case all of the segments are simultaneously moved radially outward, and the upper segment component (20a) of each segment is moved axially upward, so that the lower segment component (20b) of the segment is switched from a first radially inward holding position to a second radially outward holding position.

12. The molding method according to claim 11, comprising the steps of closing an empty curing mold, and subsequently opening the curing mold without radially retracting the segment to insert a new green tire into the curing mold.

13. The molding method according to claim 12, wherein the hardening mold is closed only in the axial direction on the green tire inserted into the hardening mold.

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