Tire building drum

Abstract

The application provides a tire forming drum, which comprises a main shaft, a middle ring and two half-drum devices symmetrically arranged relative to the middle ring. The half-drum device comprises an outer shaft sleeved on the main shaft, a limiting disc fixed to one end of the outer shaft close to the middle ring, a turn-up assembly, a turn-up driving assembly, a guide body matched with the turn-up assembly and a bead locking assembly located on the side of the limiting disc away from the middle ring. The tire forming drum further comprises a fixed ring body fixedly connected with the limiting disc and having a body part in the shape of a ring and an extension part extending axially from the body part towards the middle ring; and a movable ring body arranged between the extension part and the middle ring in the radial direction and axially movable, and the cooperation between the fixed ring body and the movable ring body forms an annular recess. Thus, the tire forming drum provided by the application not only can provide a flat circumferential surface extending axially, but also can form an annular recess for accommodating a rubber reinforcing member, so as to realize the forming of a tire body assembly in a run-flat tire blank in a one-step tire forming machine.

Description

Technical Field

[0001] The present invention relates to the technical field of tire building equipment, in particular to a tire building drum. Background Art

[0002] Existing single-stage tire building machines include a belt and tread drum and a tire building drum. The belt and tread drum is used to build the tread assembly. Specifically, tire components such as the belt, cap, and tread are sequentially bonded on the belt and tread drum to form the tread assembly. The tire building drum is used to build the carcass assembly. Specifically, the PA composite (composed of an inner liner and sidewall layers) and tire components such as the cord ply are sequentially bonded on the tire building drum. Two tire beads are symmetrically positioned radially outward of the cord ply on the tire building drum. The inflated turn-up props up the tire components located inside the beads and presses the tire components located outside the beads against the tire components located inside the beads. Furthermore, the tread assembly and carcass assembly are combined on the tire building drum to form a tire embryo.

[0003] To ensure continued driving after a tire blowout or deflation, run-flat tires have been gradually adopted by some vehicles. Run-flat tires increase the thickness and rigidity of the tire sidewalls by adding a layer of rubber reinforcement. Specifically, during the run-flat tire blank molding process, the rubber reinforcement is inserted between the inner liner and the carcass ply near the bead. After the tire blank is molded, the rubber reinforcement extends from the bead in the radial direction of the run-flat tire, positioned axially inward of the sidewall and carcass ply, and axially outward of the inner liner.

[0004] For single-stage tire building machines, the special structure of the aforementioned run-flat tires requires improvements to the structure of the tire building drum within the machine. On the one hand, the tire building drum needs to provide a flat circumferential surface to accommodate the inner liner. On the other hand, the drum also needs to be able to form a recess that matches the cross-sectional shape of the rubber reinforcement to accommodate the rubber reinforcement. This ensures that the radially outer surface of the rubber reinforcement on the drum is substantially flush with the outer surface of the inner liner outside the recess, facilitating wrapping of the carcass ply. This allows the carcass ply to be arranged in a substantially flat state, ensuring accurate splicing of the carcass ply. Furthermore, when forming the recess, the drum needs to minimize tensile deformation of the inner liner.

[0005] In view of this, it is necessary to provide an improved tire building drum for a one-step tire building machine to solve the above problems. Summary of the Invention

[0006] The present invention aims to provide a tire building drum for forming a tire body component of a run-flat tire blank in a one-step tire building machine.

[0007] To achieve the above-mentioned object, the present invention provides a tire building drum, comprising: a main shaft, a middle ring fixedly mounted on the outside of the main shaft through a middle ring support body, and two half-drum devices mounted on the main shaft and symmetrically arranged with respect to the middle ring; each half-drum device comprises:

[0008] An outer shaft, sleeved outside the main shaft;

[0009] A limiting plate is fixedly arranged on one end of the outer shaft close to the middle ring;

[0010] A turn-up assembly is disposed outside the outer shaft and is axially movable;

[0011] A turn-up drive assembly is disposed outside the outer shaft and is used to drive the turn-up assembly to move axially along the outer shaft;

[0012] a guide body, disposed outside the turn-up drive assembly, and configured to cooperate with the turn-up assembly to form a substantially continuous circumferential surface in the circumferential direction of the tire building drum, wherein the circumferential surface has a first diameter;

[0013] A bead locking assembly is provided outside the outer shaft and located on a side of the limiting plate away from the middle ring, and is used for radially supporting the bead;

[0014] a fixed ring body, fixedly connected to the limiting plate, comprising an annular main body portion and an extension portion axially extending from the main body portion toward the middle ring, wherein a radial outer surface of the extension portion has a second diameter, and the second diameter is smaller than the first diameter;

[0015] The movable ring body is arranged between the extension portion of the fixed ring body and the middle ring in the radial direction and can move axially. The cooperation between the fixed ring body and the movable ring body can form an annular recessed portion.

[0016] Furthermore, the main body of the fixed ring body is fixedly connected to the limit plate, the main body is provided with a first side edge, and the movable ring body is provided with a second side edge opposite to the first side edge. After the first side edge and the second side edge abut against each other, a basically continuous circumferential surface can be formed on the tire forming drum.

[0017] Furthermore, when the first side edge and the second side edge are not in contact, the annular recessed portion is formed by the cooperation of the first side edge, the second side edge and the extension portion, and the axial size of the annular recessed portion is adjustable.

[0018] Furthermore, the first side edge and the second side edge abut against each other in a mutually meshing manner.

[0019] Furthermore, one of the first side edge and the second side edge is provided with a convex portion, and the other of the first side edge and the second side edge is provided with a concave portion that is plugged into and fits with the convex portion, and the convex portion and the concave portion are spaced apart in the circumferential direction.

[0020] Furthermore, the half-drum device also includes: a support member, which is sleeved outside the main shaft and fixedly connected to the radial inner side of the movable ring body.

[0021] Furthermore, the extension portion includes a plurality of insert teeth arranged at intervals along the circumferential direction, and the support member is provided with through slots arranged at intervals along the circumferential direction, and the plurality of insert teeth can be inserted into the plurality of through slots.

[0022] Furthermore, the semi-drum device also includes: a third piston, which is sleeved on the outside of the main shaft and accommodated on the radial inner side of the outer shaft, one end of the third piston is fixedly connected to the support member, and the radial inner and outer sides of the third piston are respectively slidingly sealed with the main shaft and the outer shaft, and the axial movement of the third piston drives the support member and the movable ring body to move axially along the main shaft.

[0023] Furthermore, the semi-drum device also includes a guide plate, which is sleeved on the outside of the outer shaft and fixedly connected to the outer shaft, and the tire bead locking assembly is located between the guide plate and the limit plate; the turn-up assembly includes a support plate, and a plurality of turn-up rods evenly distributed along the circumference of the support plate, one end of the turn-up rod is pivotally connected to the support plate, and the other end of the turn-up rod is rotatably connected to a rolling element, and the rolling element can roll with the outer circumferential arc surface of the guide plate.

[0024] Furthermore, the turn-up drive assembly includes a cylinder and a first piston; the cylinder includes a first cylinder portion extending axially along the outer shaft, and one end of the first cylinder portion close to the middle ring is fixedly connected to the guide plate; the cylinder also includes a second cylinder portion fixedly disposed at the other end of the first cylinder portion, and the second cylinder portion extends radially inwardly along the radial direction of the outer shaft;

[0025] The first piston includes a first sliding portion, which is sleeved outside the outer shaft and extends axially along the outer shaft, and one end of the first sliding portion away from the middle ring is fixedly connected to the support plate; the first piston also includes a second sliding portion, which is fixedly disposed at the other end of the first sliding portion, and the second sliding portion extends radially outward along the radial direction of the outer shaft;

[0026] The radial inner surface of the second cylinder portion is in sliding sealing cooperation with the radial outer surface of the first sliding portion; the radial inner surface of the first cylinder portion is in sliding sealing cooperation with the radial outer surface of the second sliding portion; when the turn-up rod is in the initial position, the second sliding portion abuts against the second cylinder portion;

[0027] The guide body is in sliding sealing cooperation with the radial outer surface of the cylinder body.

[0028] Compared with the prior art, the tire building drum provided by the present invention can not only realize all the functions of the tire building drum in the existing one-step tire building machine, but also has at least the following beneficial technical effects:

[0029] (1) The tire forming drum provided by the present invention cooperates with the fixed ring body and the movable ring body, so that the tire forming drum can not only provide a continuous and flat circumferential surface to receive the inner liner, but also form an annular recess that matches the cross-sectional shape of the rubber reinforcement to accommodate the rubber reinforcement, ensuring that the radial outer surface of the rubber reinforcement on the tire forming drum is basically flush with the outer surface of the inner liner located outside the annular recess, so as to facilitate the subsequent wrapping of the carcass layer, so that the carcass layer can be arranged in a basically flat state, ensuring that the carcass layer is accurately spliced, thereby enabling the tire forming drum to be used in a one-step tire forming machine to form the carcass component in the run-flat tire embryo.

[0030] (2) In the tire forming drum provided by the present invention, since the movable ring body is accommodated on the radial inner side of the middle ring, when the movable ring body moves axially along the main shaft and away from the fixed ring body to cooperate with the formation of the annular recess for accommodating the rubber reinforcement, the movable ring body can avoid or reduce as much as possible the frictional contact with the inner liner, thereby effectively preventing the inner liner from generating tensile deformation.

[0031] (3) Since the axial movement distance of the movable ring body relative to the fixed ring body can be adjusted, the width of the annular recess can be adjusted, thereby being suitable for accommodating rubber reinforcements of different widths. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 A cross-sectional view of the tire building drum provided by the present invention in one state is shown, in which the fixed ring body and the movable ring body of the tire building drum are in contact with each other;

[0034] Figure 2 A cross-sectional view of the tire building drum provided by the present invention in another state is shown, in which an annular recessed portion is formed on the tire building drum;

[0035] Figure 3 for Figure 1 A cross-sectional view of the tire building drum half-drum device after being wrapped with an inner liner;

[0036] Figure 4 for Figure 2 A cross-sectional view of the half-drum assembly of the tire building drum after wrapping the inner liner and the rubber reinforcement, wherein the rubber reinforcement covers the radially outer side of the inner liner located outside the annular recess;

[0037] Figure 5 for Figure 2 A cross-sectional view of the tire building drum half after wrapping the inner liner and rubber reinforcement, wherein the rubber reinforcement has been pressed into the annular recess;

[0038] Figure 6 It is a schematic diagram showing that the movable ring body on the tire building drum is completely accommodated in the radial inner side of the middle ring after axial movement;

[0039] Figure 7 It is a schematic diagram showing that the movable ring body on the tire building drum is partially accommodated radially inwardly of the middle ring after axial movement;

[0040] Figure 8 This is a three-dimensional schematic diagram of a fixed ring body in a tire building drum provided by the present invention;

[0041] Figure 9 The present invention provides a three-dimensional schematic diagram of a movable ring body and its supporting member in a tire building drum.

[0042] In the picture:

[0043] 1-main shaft; 2-half drum device; 4-middle ring; 5-middle ring support;

[0044] 21-external axis;

[0045] 22-Anti-packaging component;

[0046] 221-turn-up rod; 222-support plate; 223-rolling element;

[0047] 23-turn-up drive assembly; 231-cylinder body; 232-first piston;

[0048] 24-guide plate;

[0049] 25-guide body;

[0050] 26-bead locking assembly; 261-support block; 262-seal; 263-second piston;

[0051] 27-limit plate;

[0052] 30-fixed ring body; 31-movable ring body; 32-support member; 33-third piston.

[0053] 301-main body; 302-extension portion; 3021-gear insert;

[0054] 321-through slot;

[0055] M-first side edge; N-second side edge;

[0056] A-annular concave portion; B-convex portion; C-concave portion;

[0057] 6-Inner lining; 7-Rubber reinforcement DETAILED DESCRIPTION

[0058] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0059] like Figures 1 to 9 As shown, the present invention provides a building drum, which is applied to a one-step tire building machine to form a carcass component constituting a run-flat tire blank. Specifically,

[0060] The forming drum comprises a main shaft 1 , a middle ring 4 fixedly sleeved on the main shaft 1 via a middle ring support 5 , and two half-drum devices 2 sleeved on the main shaft 1 and arranged symmetrically relative to the middle ring 4 .

[0061] Specifically, each half-drum device 2 comprises:

[0062] The outer shaft 21 is sleeved outside the main shaft 1;

[0063] A limiting plate 27 is fixedly disposed on one end of the outer shaft 21 close to the middle ring 4;

[0064] A guide plate 24 is sleeved outside the outer shaft 21 and fixedly connected to the outer shaft 21;

[0065] The bead locking assembly 26 is provided between the guide plate 24 and the limit plate 27 and is used to radially support the bead (not shown);

[0066] The turn-up assembly 22 is disposed on the outer periphery of the outer shaft 21 and is axially movable, and is used to press the tire components (not shown) located on the outside of the tire bead against the tire components on the inside of the tire bead;

[0067] The turn-up drive assembly 23 is used to drive the turn-up assembly 22 to move axially along the outer shaft 21;

[0068] The guide body 25 is sleeved on the outside of the turn-up drive assembly 23 and cooperates with the turn-up assembly 22 to form a substantially continuous circumferential surface in the circumferential direction of the forming drum, wherein the circumferential surface has a first diameter.

[0069] In order to enable the forming drum to not only provide a flat circumferential surface to receive the inner lining layer 6, but also to form an annular recess A that matches the cross-sectional shape of the rubber reinforcement 7 attached to the outside of the inner lining layer 6 to accommodate the rubber reinforcement 7, ensure that the radial outer surface of the rubber reinforcement 7 on the forming drum is basically flush with the outer surface of the inner lining layer 6 located outside the annular recess A, so as to facilitate the subsequent wrapping of the cord layer (not shown), so that the cord layer can be arranged in a basically flat state, ensuring that the cord layer is accurately spliced.

[0070] For this reason, Figure 1-4 As shown, the half drum device 2 also includes:

[0071] The fixed ring body 30 is fixedly connected to the limiting plate 27 and includes an annular main body 301 and an extension portion 302 extending axially from the main body 301 toward the middle ring 4. The radial outer surface of the extension portion 302 has a second diameter that is smaller than the first diameter.

[0072] The movable ring body 31 is radially disposed between the extension portion 302 of the fixed ring body 30 and the middle ring 4; the movable ring body 31 is axially movable relative to the extension portion 302 and the middle ring 4;

[0073] The cooperation between the fixed ring body 30 and the movable ring body 31 can form an annular recessed portion A.

[0074] Furthermore, the main body 301 of the fixed ring body 30 is fixedly connected to the limiting plate 27 ; the main body 301 is provided with a first side edge M, and the movable ring body 31 is provided with a second side edge N.

[0075] In this way, after the first side edge M and the second side edge N abut, a substantially continuous and flat circumferential surface extending in the axial direction can be formed on the tire building drum.

[0076] When the first side edge M and the second side edge N are not in contact with each other, the first side edge M, the second side edge N, and the extension portion 302 between the first side edge M and the second side edge N form the annular recess A.

[0077] In addition, since the movable ring body 31 is located radially inward of the middle ring 4, when the movable ring body 31 moves axially along the main shaft 1 and away from the fixed ring body 30 to cooperate in forming the annular recess A for accommodating the rubber reinforcement 7, the movable ring body 31 can avoid or minimize frictional contact with the inner lining layer 6, thereby effectively preventing the inner lining layer 6 from undergoing tensile deformation.

[0078] Preferably, the main body 301 and the limiting plate 27 are detachably fixedly connected, or the two are integrally formed.

[0079] Further, if Figure 6-7As shown, at least one of the first side edge M and the second side edge N is provided with a protrusion B facing the other side, and the other of the first side edge M and the second side edge N is provided with a recess C into which the protrusion B provided on the first side edge M is inserted. The radially outer surface of the protrusion B constitutes a portion of the side wall of the annular recess. As a result, the first side edge M and the second side edge N can abut each other in a mutually meshing manner.

[0080] Preferably, the convex portions B and concave portions C are alternately arranged on both the first side edge M and the second side edge N along the circumferential direction, that is, the convex portions B and the concave portions C are spaced apart in the circumferential direction.

[0081] Further, if Figure 8 As shown, the extension portion 302 includes a plurality of insert teeth 3021 spaced apart along the circumferential direction;

[0082] Further, if Figure 9 As shown, the half-drum device 2 further includes: a support member 32, which is sleeved outside the main shaft 1 and fixedly connected to the radial inner side of the movable ring body 31; the support member 32 is provided with through slots 321 arranged at intervals along the circumferential direction; the multiple insert teeth 3021 of the extension portion 302 can be inserted into the through slots 321;

[0083] Further, if Figure 1-5 As shown, the half-drum device 2 also includes: a third piston 33, which is sleeved on the outside of the main shaft 1 and accommodated on the radial inner side of the outer shaft 21. One end of the third piston 33 is fixedly connected to the support member 32. The third piston 33 is in sliding and sealing cooperation with the main shaft 1 and the outer shaft 21 to drive the support member 32 to move axially along the main shaft, thereby driving the ring 4 in the movable ring body 31 to slide and cooperate.

[0084] Next, combine Figure 1-5 Detailed description of the specific structure of other components in the building drum and their coordination relationship.

[0085] Furthermore, the turn-up assembly 22 includes a support plate 222 and a plurality of turn-up rods 221 evenly distributed along the circumference. One end of the turn-up rod 221 is pivotally connected to the support plate 222, and the other end of the turn-up rod 221 is rotatably connected to a rolling element 223. The rolling element 223 is capable of rolling engagement with the outer circumferential arcuate surface of the guide plate 24.

[0086] Furthermore, the turn-up drive assembly 23 includes a cylinder 231 and a first piston 232. The cylinder 231 includes a first cylinder portion extending axially along the outer shaft 21, and one end of the first cylinder portion adjacent to the middle ring 4 is fixedly connected to the guide plate 24. The cylinder 231 also includes a second cylinder portion fixedly disposed at the other end of the first cylinder portion, and the second cylinder portion extends radially inwardly along the radial direction of the outer shaft 21.

[0087] The first piston 232 includes a first sliding portion, which is sleeved outside the outer shaft 21 and extends axially along the outer shaft 21. The end of the first sliding portion away from the middle ring 4 is fixedly connected to the support plate 222. The first piston also includes a second sliding portion, which is fixedly disposed at the other end of the first sliding portion and extends radially outward along the radial direction of the outer shaft 21.

[0088] The radial inner surface of the second cylinder portion is slidably sealed with the radial outer surface of the first sliding portion; the radial inner surface of the first cylinder portion is slidably sealed with the radial outer surface of the second sliding portion; when the turn-up rod 221 is in the initial position, the second sliding portion abuts against the second cylinder portion.

[0089] Thus, a first chamber is formed between the cylinder body 231 and the first piston 232. When compressed gas fills this first chamber, the first piston 232 moves axially along the outer shaft 21, driving the support plate 222 to move axially along the outer shaft 21. Furthermore, the radially outer surface of the guide body 25 is provided with a plurality of axially extending guide grooves for accommodating the turn-up rod 221. The guide body 25 is also capable of sliding relative to the cylinder body 231 of the turn-up drive assembly 23 to selectively accommodate the rolling element 223 radially inwardly thereof. Thus, when the turn-up rod 221 is in the initial position, the guide body 25 cooperates with the turn-up assembly 22 to form a substantially flat circumferential surface. Furthermore, the guide body 25 and the radially outer surface of the cylinder body 231 are in sliding and sealing engagement.

[0090] Furthermore, the bead locking assembly 26 includes: a plurality of support blocks 261 arranged in a circumferential array, which are arranged between the guide plate 24 and the limit plate 27; a seal 262, which is arranged on the radial outside of the support block 261; and a second piston 263, the radial outside of the second piston 263 forms a conical surface fit with the support block 261.

[0091] Next, combine Figure 3-5 The invention also provides a molding process for a run-flat tire blank in a one-step tire molding machine, and describes in detail the working process of the molding drum of the invention.

[0092] In the first stage, the first tire layer material (the inner liner 6 or the PA composite formed by splicing the inner liner 6 and the sidewall layer (not shown)) needs to be laminated on the forming drum. Figure 3 In the figure, the turn-up assembly 22 is in its initial position, the turn-up rod 221 is accommodated in the guide groove of the guide body 25, the rolling element 223 is accommodated radially inwardly of the guide body 25, and the second side edge N of the movable ring body 31 abuts the first side edge M of the main body 301 of the fixed ring body 30. Thus, a substantially flat circumferential surface extending in the axial direction is formed on the building drum to receive the inner liner 6.

[0093] In the second stage, two rubber reinforcements 7 need to be attached to the outer side of the inner lining 6 at the annular recess on the forming drum. Figure 4-5 As shown, the movable ring body 31 moves axially along the main shaft 1, away from the fixed ring body 30, and further accommodated radially inwardly of the middle ring 4, thereby forming an annular recess A for accommodating the rubber reinforcement 7. The shape of the annular recess substantially matches the cross-sectional shape of the rubber reinforcement 7. The rubber reinforcement 7 is bonded to the radially outer side of the inner liner 6 at the annular recess A. During the bonding process, an external force is applied to the rubber reinforcement 7, causing the inner liner 6 and the rubber reinforcement 7 at the annular recess A to be contained within the annular recess A. This ensures that the radial outer surface of the rubber reinforcement 7 on the building drum is substantially flush with the outer surface of the inner liner 6 outside the annular recess A, facilitating subsequent wrapping of the carcass ply. This allows the carcass ply to be arranged in a substantially flat state, ensuring accurate carcass splicing. During the formation of the annular recess A, the movable ring body 31 avoids or minimizes frictional contact with the inner liner 6, effectively preventing tensile deformation of the inner liner 6.

[0094] Compared with the prior art, the tire building drum provided by the present invention can not only realize all the functions of the tire building drum in the existing one-step tire building machine, but also has at least the following beneficial technical effects:

[0095] (1) The tire forming drum provided by the present invention cooperates with the fixed ring body 30 and the movable ring body 31, so that the tire forming drum can not only provide a continuous and flat circumferential surface to receive the inner liner 6, but also form an annular recess A that matches the cross-sectional shape of the rubber reinforcement 7 to accommodate the rubber reinforcement 7, ensuring that the radial outer surface of the rubber reinforcement 7 on the tire forming drum is basically flush with the outer surface of the inner liner 6 located outside the annular recess A, so as to facilitate the subsequent wrapping of the carcass layer, so that the carcass layer can be arranged in a basically flat state, ensuring that the carcass layer is accurately spliced, thereby enabling the tire forming drum to be used in a one-step tire forming machine to form the carcass component in the run-flat tire embryo.

[0096] (2) In the tire forming drum provided by the present invention, since the movable ring body 31 is accommodated on the radial inner side of the middle ring 4, when the movable ring body 31 moves axially along the main shaft and away from the fixed ring body 30 to cooperate in forming the annular recess A for accommodating the rubber reinforcement 7, the movable ring body 31 can avoid or reduce as much as possible the frictional contact with the inner lining layer 6, thereby effectively preventing the inner lining layer 6 from generating tensile deformation.

[0097] (3) Since the axial movement distance of the movable ring body 31 relative to the fixed ring body 30 can be adjusted, the axial width of the annular recess A can be adjusted, thereby being suitable for accommodating rubber reinforcements of different widths.

[0098] The specific examples described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tire building drum comprising: A main shaft, a middle ring fixedly mounted on the outside of the main shaft through a middle ring support, and two half-drum devices mounted on the main shaft and symmetrically arranged with respect to the middle ring; each half-drum device comprises: An outer shaft, sleeved outside the main shaft; A limiting plate is fixedly arranged on one end of the outer shaft close to the middle ring; A turn-up assembly is disposed outside the outer shaft and is axially movable; A turn-up drive assembly is disposed outside the outer shaft and is used to drive the turn-up assembly to move axially along the outer shaft; a guide body, disposed outside the turn-up drive assembly, and configured to cooperate with the turn-up assembly to form a substantially continuous circumferential surface in the circumferential direction of the tire building drum, wherein the circumferential surface has a first diameter; A bead locking assembly is provided outside the outer shaft and located on a side of the limiting plate away from the middle ring, and is used for radially supporting the bead; a fixed ring body, fixedly connected to the limiting plate, comprising an annular main body portion and an extension portion axially extending from the main body portion toward the middle ring, wherein a radial outer surface of the extension portion has a second diameter, and the second diameter is smaller than the first diameter; a movable ring body, which is radially disposed between the extension portion of the fixed ring body and the middle ring and is axially movable, wherein the fixed ring body and the movable ring body cooperate to form an annular recess; The main body of the fixed ring body is fixedly connected to the limiting plate, the main body is provided with a first side edge, and the movable ring body is provided with a second side edge opposite to the first side edge, and when the first side edge and the second side edge abut against each other, a substantially continuous circumferential surface can be formed on the tire building drum; When the first side edge and the second side edge are not in contact, the annular recessed portion is formed by the cooperation of the first side edge, the second side edge and the extension portion, and the axial size of the annular recessed portion is adjustable.

2. A tire building drum according to claim 1, characterized in that: The first side edge and the second side edge abut against each other in a mutually engaged manner.

3. A tire building drum according to claim 2, characterized in that: One of the first side edge and the second side edge is provided with a convex portion, and the other of the first side edge and the second side edge is provided with a concave portion plug-fitted with the convex portion, and the convex portion and the concave portion are spaced apart in the circumferential direction.

4. A tire building drum according to claim 1, characterized in that: The half-drum device further comprises: a support member, which is sleeved outside the main shaft and fixedly connected to the radial inner side of the movable ring body.

5. A tire building drum according to claim 4, characterized in that: The extension portion includes a plurality of insert teeth arranged at intervals along the circumferential direction, and the support member is provided with through slots arranged at intervals along the circumferential direction, and the plurality of insert teeth can be inserted into the plurality of through slots.

6. A tire building drum according to claim 4 or 5, characterized in that: The half-drum device also includes: a third piston, which is sleeved on the outside of the main shaft and accommodated on the radial inner side of the outer shaft. One end of the third piston is fixedly connected to the support member. The radial inner and outer sides of the third piston are respectively slidingly sealed with the main shaft and the outer shaft. The axial movement of the third piston drives the support member and the movable ring body to move axially along the main shaft.

7. The tire building drum according to claim 1, characterized in that: The semi-drum device also includes a guide plate, which is sleeved on the outside of the outer shaft and fixedly connected to the outer shaft. The tire bead locking assembly is located between the guide plate and the limit plate; the turn-up assembly includes a support plate and a plurality of turn-up rods evenly distributed along the circumference of the support plate, one end of the turn-up rod is pivotally connected to the support plate, and the other end of the turn-up rod is rotatably connected to a rolling element, and the rolling element can roll with the outer circumferential arc surface of the guide plate.

8. The tire building drum according to claim 7, characterized in that: The turn-up drive assembly includes a cylinder and a first piston; the cylinder includes a first cylinder portion extending axially along the outer shaft, and one end of the first cylinder portion close to the middle ring is fixedly connected to the guide plate; the cylinder also includes a second cylinder portion fixedly disposed at the other end of the first cylinder portion, and the second cylinder portion extends radially inwardly along the radial direction of the outer shaft; The first piston includes a first sliding portion, which is sleeved outside the outer shaft and extends axially along the outer shaft, and one end of the first sliding portion away from the middle ring is fixedly connected to the support plate; the first piston also includes a second sliding portion, which is fixedly disposed at the other end of the first sliding portion, and the second sliding portion extends radially outward along the radial direction of the outer shaft; The radial inner surface of the second cylinder portion is in sliding sealing cooperation with the radial outer surface of the first sliding portion; the radial inner surface of the first cylinder portion is in sliding sealing cooperation with the radial outer surface of the second sliding portion; when the turn-up rod is in the initial position, the second sliding portion abuts against the second cylinder portion; The guide body is in sliding sealing cooperation with the radial outer surface of the cylinder body.

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