JP2009274392A - Molding drum of tire member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding drum of a tire member which can keep circularity even when expanding/contracting the diameter of segments. <P>SOLUTION: This molding drum 1 of a tire member is for molding a ring-shaped tire member by winding a tire material around the outer peripheral surface O of a nearly cylindrical drum, and comprises a rotatably supported center shaft, a plurality of segments 7 arranged around the center shaft and constituting the outer peripheral surface of the drum and a segment moving means for expansively/contractively moving the segments 7 in the radial direction of the drum. Each segment 7 comprises a main segment piece 8 moving in the radial direction of the drum by the segment moving means, and inflective segment pieces 9 pivoted like a cantilever at one side edge 8a in the circumferential direction of the main segment piece 8 and inflectively around the axial line along the drum shaft direction. The end part of free end 9f side of each inflective segment piece 9 is loaded on the outer surface of the main segment piece 8 of another segment adjacent at the free end side, and an energizing means 10 for energizing the inflective segment piece 9 to the radially inner direction of the drum is provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a molding drum useful for accurately molding a ring-shaped tire member such as a tread rubber, an inner liner and / or a sidewall rubber.

  For example, as shown in FIG. 6, a substantially cylindrical drum outer peripheral surface O is provided, and a belt-shaped tire material such as a belt ply or a band ply of a pneumatic tire is wound around the drum-shaped tread reinforcing layer B. A molding drum a1 for molding (tire member) is known (see, for example, Patent Document 1).

  In recent years, a tread rubber, an inner liner, a sidewall rubber, and further a chafer rubber are formed by winding an unvulcanized ribbon-like rubber strip s on the forming drum a1 in a spiral manner in the circumferential direction. (Hereinafter, such a process may be referred to as a “strip wind process”). In this strip winding process, one end of the rubber strip s is fixed on the molding drum a1 (or on the tread reinforcing layer B), and then the molding drum a1 is rotated and a predetermined position is changed while changing the axial position of the rubber strip s. A tire member (rubber member) having a cross-sectional shape is formed. The rubber strip s is pressed by a roller r that is lightly biased toward the molding drum a1.

  As a general forming drum structure, for example, as shown in FIG. 7, a plurality of arms b extending radially from the central axis f of the forming drum a1 in the drum radial direction, and fixed to the arms b. In addition, a plurality of equally-divided arcuate segments c forming a substantially cylindrical drum outer peripheral surface O are provided by being arranged in the circumferential direction. In such a forming drum a1, in the state of the outer diameter d1, the segment c is continuous without a gap in the circumferential direction, so that a tire member having a high roundness can be accurately formed.

  However, when the arm b is extended to have an outer diameter d2 or d3 larger than the outer diameter d1, a gap g is generated between the adjacent segments c and c, and sufficient roundness cannot be ensured. For this reason, in such a forming drum a1, there exists a problem that the tire member which has several internal diameter cannot be shape | molded accurately. In particular, when the rubber strip is wound directly on the molding drum, the above-described problem becomes remarkable, for example, when the roundness of the molding drum is low, the sticking position is easily shifted.

  In order to solve the above problem, for example, a forming drum a2 as shown in FIG. 8 has been proposed. The forming drum a2 includes, as the segment c, a first segment c1 having a large circumferential length and a second segment c2 having a small circumferential length, and these are alternately provided in the circumferential direction. In such a forming drum a2, as shown on the lower side in FIG. 8, only the first segment c1 is connected in the circumferential direction to obtain a small diameter state of the outer diameter d1, whereas on the upper side in FIG. In addition, the first and second segments c1 and c2 can be alternately connected to obtain an expanded state of the outer diameter d2. In any state, the gap between the segments can be made relatively small. Therefore, with this molding drum a2, two types of tire members having different inner diameters can be molded.

JP-A-6-344465

  However, the molding drum a2 also has room for improvement because it is small but has a gap between the segments.

  Further, when the small diameter state of the outer diameter d1 is obtained by using only the first segment c1, the number of divisions of the drum outer peripheral surface O is reduced to half that in the expanded diameter state, and the roundness is decreased and tread reinforcement is performed. There is a possibility that the forming accuracy of the layer B may be deteriorated. In particular, in such a small diameter state with a low roundness, the rubber member in which the roller r that presses the rubber strip s frequently jumps up and down due to the unevenness of the molding drum in the strip winding process, and the rubber strip cannot be pressed sufficiently. There was also a possibility of deteriorating the molding accuracy.

  The present invention has been devised in view of the actual situation as described above, and each segment is divided into a main segment piece that is expanded and contracted by the segment moving means, and one side edge of the main segment piece in the drum circumferential direction. And a bent segment piece pivotally attached to bendable about an axis along the drum axis direction, and an end portion of each bent segment piece on the outer surface of the adjacent main segment piece. In addition to placing the bent segment piece on the inside of the drum in the radial direction of the drum, it prevents the gap between segments from occurring even if the diameter is different, and maintains high roundness. A molding drum useful for accurately molding tire members such as tread reinforcement layers, sidewall rubber, inner liner rubber or chafer rubber having multiple types of diameters It has been the main purpose of providing.

  The invention according to claim 1 of the present invention is a tire drum for forming a ring-shaped tire member by winding a tire material around a substantially cylindrical drum outer peripheral surface, and is rotatably supported. A central axis, a plurality of segments arranged around the central axis and constituting the outer peripheral surface of the drum, and segment moving means for expanding and contracting the segments in the radial direction of the drum with respect to the central axis, The segment is bendable around a main segment piece that moves in the drum radial direction by the segment moving means, and an axial line that extends along the drum axis in a cantilevered side edge of the main segment piece in the drum circumferential direction. End portions on the free end side of each of the bent segment pieces are overlapped on the outer surface of the adjacent main segment piece on the free end side. Together is placed, characterized in that a biasing means for biasing the bend segment piece to the drum radially inward.

  According to a second aspect of the present invention, the outer surface of the main segment piece includes a reference surface forming a part of the outer peripheral surface of the drum around which a tire member is wound, and a bent segment piece having an outer diameter smaller than the reference surface. It is a forming drum of the tire member according to claim 1 including a mounting surface for support.

  According to a third aspect of the present invention, each segment has a substantial outer surface of the main segment piece and an outer surface of the bent segment piece while maintaining the overlap of the main segment piece and the bent segment piece. The molding of a tire member according to claim 1 or 2, wherein the tire member is at least expanded / contracted between a reference outer diameter state continuous at the same outer diameter and a 2-inch expanded state whose outer diameter is 2 inches larger than the reference outer diameter state. It is a drum.

According to a fourth aspect of the present invention, in the tire member forming drum according to the first or second aspect, the segments are arranged uniformly in the tire circumferential direction and satisfy the following expression (1).
Ls> 50.8π / n (1)
Where π is the circumference ratio, n is the total number of segments per drum, and Ls is a reference outer diameter in which the outer surface of the main segment piece and the outer surface of the bent segment piece are substantially the same outer diameter. The circumferential overlap length (mm) in the state.

  According to the first aspect of the present invention, each segment has a main segment piece that moves in the drum radial direction by the segment moving means, and a cantilevered side edge in the drum circumferential direction of the main segment piece in the drum axial direction. A bent segment piece pivotally attached to be bent about an axis along the axis, and an end portion on the free end side of each bent segment piece is on an outer surface of a main segment piece of another segment adjacent to the free end side Placed with overlap. Moreover, the bent segment piece is urged inward in the drum radial direction by the urging means. In such a forming drum, even when the diameter of the main segment piece is increased, it is possible to prevent a gap from being generated between the segments due to the overlapping of the bent segment piece and the main segment piece. In particular, since the bent segment piece is urged inward in the drum radial direction by the urging means, the bent segment piece comes into contact with the adjacent main segment piece on the free end side of the bent segment piece and follows the change in its diameter. To do. For this reason, the fall of the roundness of the drum outer peripheral surface of a segment can be prevented. In the molding drum according to the first aspect, the number of divisions on the outer peripheral surface of the drum is not substantially changed between the diameter expansion and the diameter reduction. Therefore, it is possible to improve the roundness of the molding drum in both the state of diameter expansion and the state of diameter reduction. Therefore, for example, a strip wind method can be performed with high accuracy.

  According to a second aspect of the present invention, the outer surface of the main segment piece is a reference surface that forms part of the outer peripheral surface of the drum, and the mounting surface for supporting the bent segment piece that has an outer diameter smaller than the reference surface. Can be prevented, the bent segment piece placed on the main segment piece can be prevented from being lifted. This is useful for smoothly and continuously improving the roundness of the drum outer peripheral surface.

  In order to form a plurality of types of tires having different inch numbers, it is necessary to form tire members having at least an inner diameter of about 2 inches. Therefore, as in the invention according to claim 3 or 4, each segment substantially maintains the outer surface of the main segment piece and the outer surface of the bent segment piece while maintaining the overlap of the main segment piece and the bent segment piece. The tire member having a different tire size can be moved at least between a reference outer diameter state continuous at the same radius and a 2-inch expanded state whose outer diameter is 2 inches larger than the reference outer diameter state. It can be molded with good accuracy while maintaining roundness.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional view of a forming drum 1 of the present embodiment, FIG. 2 is an enlarged view of a main part thereof, and FIG. 3 is an AA partial enlarged end view of FIG. In the figure, a forming drum 1 is supported by a main body frame 2, a horizontal central shaft 3 which is rotatably supported by bearings B 1 and B 2 provided on the main body frame 2 and cantilevered, and the central shaft 3. And a drum main body 4 having a substantially cylindrical drum outer peripheral surface O. In the present specification, the drum body 4 side (right side) in FIG. 1 is described as one end side S1, and the opposite side is described as the other end side S2.

  The main body frame 2 includes a first side wall 2A disposed on one end side S1 and having a bearing B1, and a bearing B2 disposed on the other end side S2 at a distance and provided coaxially with the bearing B1. It includes a second side wall portion 2B and an upper plate portion 2C disposed between the upper ends of the first and second side wall portions 2A, 2B. The main body frame 2 can support the weight of the drum main body 4 by being fixed to a floor surface (not shown), for example.

  In the present embodiment, the central shaft 3 has a cylindrical shape with a void therein, and an air pipe 5 through which high-pressure air to be supplied to the drum body 4 flows is inserted into the void. High pressure air is supplied to the end 5a of the other end S2 of the air pipe 5 from, for example, a compressor. A branch port 5b having one or more connection ports is provided at the end of one end S1 of the air pipe 5, and high-pressure air is supplied to necessary portions via a hose (not shown). For example, the high-pressure air is used as drive energy for driving various components and mechanisms, and is supplied between the drum outer peripheral surface O and a tire member molded thereon, and the tire member is supplied from the drum outer peripheral surface. Used when peeling.

  Further, the central shaft 3 protrudes from the bearing B2 to the other end S2, and a pulley 11 is fixed thereto. Further, the torque of the first electric motor (not shown) is transmitted to the pulley 11 via the belt 6. Therefore, the central shaft 3 can be rotated around the horizontal axis by driving the first electric motor.

  The drum body 4 is arranged in the drum circumferential direction around the central axis 3 to form a plurality of segments 7 constituting a substantially cylindrical drum outer peripheral surface O, and the segments 7 are drums with respect to the central axis 3. Segment moving means for expanding and contracting in the radial direction.

  The segment moving means includes an elongated guide groove 12 provided in the central shaft 3 extending in the axial direction, a slide cylinder 13 capable of sliding in the axial direction inside the central shaft 3, and fixed to the slide cylinder 13. The projecting piece 14 projecting outward from the guide groove 12, the link portion 26 connected to the projecting piece 14 via a slide ring 27 (shown in FIG. 2), and the slide cylinder 13 in the axial direction. And a drive unit 23 to be slid.

  In the present embodiment, the guide groove 12 is provided in a portion extending inward of the segment 7 of the central shaft 3, and is formed in the first guide groove 12A formed on one end side S1 and the other end side S2. It consists of a pair with the second guide groove 12B. Each guide groove 12A, 12B penetrates the central axis 3 respectively. The guide grooves 12 </ b> A and 12 </ b> B are formed with a slightly larger groove width than the projecting piece 14 to allow the projecting piece 14 to slide.

  In the present embodiment, the slide cylinder 13 has a cylindrical shape, and is slidable in the axial direction between the inner peripheral surface of the central shaft 3 and the outer peripheral surface of the air pipe 5.

  The projecting piece 14 includes a first projecting piece 14A projecting from the first guide groove 12A and a second projecting piece 14B projecting from the second guide groove 12B. A slide ring 27 is fixedly attached to each of the projecting pieces 14A and 14B. The slide ring 27 is fitted on the outer peripheral surface of the central shaft 3 and can slide in the axial direction. Accordingly, each of the projecting pieces 14 </ b> A and 14 </ b> B and the slide ring 27 can move in the axial direction integrally with the slide cylinder 13. Further, a ring-shaped flange piece F surrounding the outer peripheral surface of the central shaft 3 is fixed to the other end side S2 of the second projecting piece 14B. The inner diameter of the flange piece F is formed larger than the outer diameter of the central shaft 3. Therefore, this flange piece F can also move integrally with the slide cylinder 13 without interfering with the central shaft 3. In addition, since the torque is transmitted to the projecting piece 14 by the groove wall surface of the guide groove 12 by the rotation of the central shaft 3, the projecting piece 14, the slide cylinder 13, and the flange piece F can rotate together with the central shaft 3.

  The link portion 26 includes a first link portion 26A and a second link portion 26B that are connected to the first protrusion 14A and the second protrusion 14B, respectively. Each of the link portions 26A and 26B includes a long main link 28a and an auxiliary link 28b shorter than the main link 28a.

  One end of the main link 28a on the inner side in the drum radial direction is pivotally attached to the slide ring 27 and the other end on the outer side in the drum radial direction is pivotally attached to the base portion 25 on the inner peripheral surface side of the segment 7 by a pin 29. Is done. The auxiliary link 28b has an effective link length that is ½ that of the main link 28a. The auxiliary link 28b has an end on the inner side in the drum radial direction fixed to the fixed protrusion 30 fixed to the central shaft 3, and the other on the outer side in the drum radial direction. The ends are pivotally attached to intermediate positions of the effective link length of the main link 28a.

  In the present embodiment, each main link 28a is provided to be inclined from the other end side S2 to the one end side S1 toward the outer side in the drum radial direction, while the auxiliary link 28b is provided with an inclination opposite to the main link 28a. It is done. Such a link portion 26 is tilted in the direction in which the main link 28a is raised, thereby pushing the segment 7 outward in the radial direction of the drum and expanding the outer peripheral surface O of the drum while tilting in the direction in which the main link 28a is laid down. Thus, the segment 7 is drawn inward in the drum radial direction, and the outer peripheral surface O of the drum can be reduced in diameter.

  The drive unit 23 includes a motion conversion unit 15 that converts a rotational motion obtained from a second electric motor (not shown) into a horizontal linear motion, a rod member 16 connected to the motion conversion unit 15, and the rod member 16. And a connecting portion 17 that connects the flange piece F.

  The motion converting means 15 includes a horizontal screw shaft 18 extending from the second side wall portion 2B to one end S1 and having a screw groove 18A, a ball nut portion 19 screwed into the screw shaft 18, and the ball The movable frame 20 is configured to be fixed to the nut portion 19 and has a through hole 20A through which the central shaft 3 passes.

  The other end side S2 of the screw shaft 18 is rotatably supported by a bearing B3 provided on the second side wall portion 2B. Further, the torque of a second electric motor (not shown) is transmitted to the screw shaft 18 via the sprocket 22 and the chain 21.

  The moving frame 20 extends, for example, toward the upper plate 2C side, and a through hole 20A through which the central shaft 3 passes is provided at a substantially central portion thereof.

  The rod member 16 has an end portion 16a on the other end side S2 fixed to the moving frame 20, and an end portion 16b on one end side S1 has a horizontal axis by a linear motion bearing 24 provided on the second side wall portion 2A. It is slidably supported only in the direction and extends to the drum body 4 side.

  The connecting portion 17 includes a disc-shaped side plate 17a having a through hole 17H through which the central shaft 3 passes, a cylindrical outer cylinder portion 17b fixed to the side plate 17a, and a bearing 17c on the outer cylinder portion 17b. The inner cylinder part 17d that can be rotated independently of the outer cylinder part 17b by being inserted, and the joint cylinder 17e that connects the inner cylinder part 17d and the flange piece F are configured. The The end 16b of the rod member 16 is fixed to the side plate 17a.

The operation of the drive unit 23 as described above will be described.
By driving a second electric motor (not shown), the torque is transmitted to the chain 21, the sprocket 22, and the screw shaft 18 to rotate them. The ball nut portion 19 whose rotation is restricted by the moving frame 20 moves in the axial direction by the rotation of the screw shaft 18, and the projecting piece 14 and the slide cylinder 13 are pivoted through the moving frame 20, the rod member 16 and the connecting portion 17. Can be moved in the direction. Then, for example, by moving the slide cylinder 13 to the one end side S1, the main link 28a can be tilted in the direction in which the main link 28a is raised, and the segment 7 can be expanded in diameter. On the contrary, by moving the slide cylinder 13 to the other end S2, the segment 7 can be reduced in diameter by tilting the main link 28a in the direction to lay down. The direction of movement of the slide cylinder 13 is performed by controlling the rotation direction of the second electric motor. Further, when the first electric motor is driven to rotate the central shaft 3, the drum body 4 can be rotated together with the central shaft 3 via the projecting piece 14 and the link portion 26. At this time, the side plate 17a and the rod member 16 are not rotated by the bearing 17c.

  As shown in FIGS. 3 and 4, the substantially cylindrical drum outer peripheral surface O is formed by arranging a plurality of segments 7 around the central axis 3. In the present embodiment, twelve segments 7 are arranged evenly in the circumferential direction (in other words, each segment 7 has the same shape).

  Each segment 7 has a main segment piece 8 moved in the drum radial direction by the segment moving means, and a side edge 8a on one side of the drum circumferential direction of the main segment piece 8 around the axis line along the drum axis direction. And a bent segment piece 9 pivotably mounted in a cantilever manner. In other words, the drum outer peripheral surface O of the present embodiment is configured by alternately arranging 12 main segment pieces 8 and 12 bent segment pieces 9.

  The main segment piece 8 is made of an arc-shaped metal material having a predetermined axial length and curved around an axis along the central axis 3. In the present embodiment, the base portion 25 including the substrate 25 a and the link attachment portion 25 b is fixed to the inner side surface 8 i of the main segment piece 8 with, for example, bolts 35. Further, as described above, the main link 28a of the segment moving means is pivotally attached to the base portion 25. Therefore, the main segment piece 8 is directly moved in the drum radial direction by tilting (segment moving means) of the main link 28a.

  The bent segment piece 9 has an axial length substantially equal to that of the main segment piece 8 and is made of an arc-shaped metal material that is curved around the axis along the central axis 3. In addition, the bent segment piece 9 is connected to one side edge 8a of the main segment piece 8 via a hinge 31 that can be opened and closed around an axis along the drum axis direction in this embodiment. The hinge 31 is fixed across the inner side surfaces 8 i and 9 i of the main segment piece 8 and the bent segment piece 9. Accordingly, the bent segment piece 9 is connected to the main segment piece 8 and is pulled by the main segment piece 8 and can move in the radial direction.

  Further, as shown in FIG. 3, the end portion 9f on the free end side of each bent segment piece 9 overlaps the outer surface of the main segment piece 8 of another adjacent segment 7 (overlap length in the circumferential direction). And an urging means 10 for urging the bent segment piece 9 inward in the drum radial direction.

  In the present embodiment, the outer surface 8o of the main segment piece 8 includes a reference surface 8o1 made of an arc surface that forms a part of the drum outer peripheral surface O, and a bent segment piece made of an arc surface having an outer diameter smaller than the reference surface 8o1. And a mounting surface 8o2 for support. As a result, as shown in FIG. 3, the bent segment piece 9 placed on the main segment piece 8 is prevented from being lifted excessively from the main segment piece 8, and the drum outer periphery can be smoothly smoothed with higher roundness. The plane O can be made continuous. This is useful for accurately molding the tire member.

  In this embodiment, the difference (R1a−R1b) between the radius R1a of the reference surface 8o1 and the radius R1b of the placement surface 8o2 is substantially equal to the thickness t of the bent segment piece 9 placed on the placement surface 8o2. Is set equal to. The radius (curvature radius) R2 of the outer surface 9o of the bent segment piece 9 is set equal to the radius R1a of the reference surface 8o1 (R1a = R2). Further, as shown in FIG. 3, when the main segment piece 8 and the end portion 9f on the free end side of the bent segment piece 9 are overlapped with each other, the mounting surface is arranged such that their outer peripheral surfaces are continuous without gaps. The shape of 8o2 and the cross-sectional shape of the end portion 9f on the free end side can be determined. In other words, the outline of the mounting surface 8o2 can be determined by cutting out the cross section of the end portion on the free end side of the bent segment piece 9 from the reference surface 8o1 of the main segment piece 8. By these, the roundness of the drum outer peripheral surface O can be further improved.

  In FIG. 3, the reference outer diameter state in which the radius Ds of the drum outer peripheral surface O forms the curvature radius R1a of the reference surface 8o1 of the main segment piece 8 (that is, the curvature radius R2 of the outer surface 9o of the bent segment piece 9). It is shown.

  The biasing means 10 of the present embodiment includes a protruding shaft 10A that protrudes inward in the drum radial direction from the inner side surface 8i of the main segment piece 8, and a protrusion that protrudes inward in the drum radial direction from the inner side surface 9i of the bent segment piece 9. And a coil spring 10C that spans between the projecting shafts 10A and 10B and urges the shafts toward each other.

  In the forming drum 1 configured as described above, as shown in FIG. 5, each main segment piece 8 is moved in the drum radial direction by the segment moving means, and the drum outer peripheral surface O is in the reference outer diameter state ST1 having the radius Ds. Even when expanded to a diameter-enlarged state with a radius Dm, the overlap between the main segment piece 8 and the bent segment piece 9 is maintained and a gap is prevented from being generated between the segments 7. This can prevent deterioration of the roundness of the drum outer peripheral surface O. In the molding drum 1 of the present embodiment, the overlapping length L between the bent segment piece 9 and the main segment piece 8 decreases as the diameter of the drum outer peripheral surface O increases, and a depression E is formed on the surface of the drum outer peripheral surface O. Arise. However, since this depression E has a bottomed shape due to the mounting surface 8o2 of the main segment piece 8, it is preferable in that the tire member wound around the depression E can be prevented from being deformed excessively inward in the radial direction.

  In the expanded diameter state ST2, the radius Dm of the drum outer peripheral surface O is larger than the curvature radii R1a and R2 of the outer surfaces of the segment pieces 8 and 9, so that it does not become a perfect circle. However, the bent segment piece 9 can be bent with respect to the main segment piece 8 and is urged inward in the drum radial direction by the urging means 10, so that the diameter of the adjacent main segment piece 8 on the free end side can be changed. Following the bending deformation, the drum outer peripheral surface O is reduced as much as possible from being uneven. Thereby, the fall of the roundness of the drum outer peripheral surface O can be prevented more reliably. Furthermore, in the forming drum 1 of the present embodiment, the number of divisions of the drum outer peripheral surface O does not substantially change even when the outer diameter of the drum outer peripheral surface O is changed. Accordingly, it is possible to improve the roundness of the outer peripheral surface O of the drum in both the states of diameter expansion and contraction. For example, the tread reinforcement layer wound around the drum outer peripheral surface O increases the overlap length of the main segment piece 8 and the bent segment piece 9 to the extent that the link portions 28 do not interfere with each other, and can be easily set as the minimum diameter state ST0. Can be removed.

  Further, in order to form a plurality of types of tires having different numbers of inches, it is necessary to form tire members having at least an inner diameter of about 2 inches. Therefore, in order to form such a tire member with one molding drum 1, the reference outer diameter state ST1 and the reference outer diameter state are maintained while maintaining the overlap of the main segment piece 8 and the bent segment piece 9. It is preferable to move at least the expansion and contraction between the diameter expansion state of 2 inches larger than ST1 by 2 inches. Thereby, tread reinforcement layers of different tire sizes can be molded with high accuracy while maintaining high roundness.

Specifically, as the diameter of the cylinder increases by 2 inches, its circumferential length increases by 2π inches, or 50.8π (mm). On the other hand, if the total number of segments per drum is n and the overlapping length of the main segment piece 8 and the bent segment piece 9 in the reference outer diameter state is Ls (mm), the total sum of the overlapping lengths is Ls · n ( mm). Therefore, in order to at least expand and contract between the reference outer diameter state ST1 and the 2 inch diameter expanded state while maintaining the overlap between the main segment piece 8 and the bent segment piece 9, the following equation should be satisfied. .
Ls> 50.8π / n (1)

  As mentioned above, although the especially preferable form of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect. For example, the biasing means 10 of the present embodiment is configured by bridging the coil spring 10C around the projecting shafts 10A and 10B, but instead of such a mode, for example, the main segment piece 8 using a leaf spring is used. And the bent segment piece 9 may be connected to each other, or a spring hinge incorporating a spring into the hinge 31 may be used.

It is a fragmentary sectional view of the forming drum of the tire member of this embodiment. It is an expanded sectional view of the drum. It is an AA partial expanded end view of FIG. It is a principal part perspective view of a segment. It is a fragmentary sectional view showing each diameter reduction state of a segment. It is a fragmentary sectional view which shows the expansion / contraction state of a drum outer peripheral surface. It is a fragmentary sectional view showing the conventional forming drum. It is a fragmentary sectional view showing the conventional forming drum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Forming drum 3 Center axis | shaft 4 Drum main body 7 Segment 8 Main segment piece 8a Side edge 9 of main segment piece Bending segment piece 9f End part 10b of free end side of bending segment piece Energizing means O Drum outer peripheral surface

Claims (4)

A tire member forming drum for forming a ring-shaped tire member by winding a tire material around a substantially cylindrical drum outer peripheral surface,
A central axis rotatably supported;
A plurality of segments arranged around the central axis and constituting the outer peripheral surface of the drum;
Segment moving means for expanding and contracting the segment in the radial direction of the drum with respect to the central axis,
Each segment is bent around an axis along the drum axis direction in a cantilevered manner at a side edge on one side in the drum circumferential direction of the main segment piece by the segment moving means in the drum radial direction. The bent segment pieces pivotably attached to each other, and the end portions of the respective bent segment pieces on the free end side are placed on the outer surface of the adjacent main segment pieces with an overlap. With
A tire member forming drum, comprising a biasing means for biasing the bent segment piece inward in the drum radial direction.   The outer surface of the main segment piece includes a reference surface that forms a part of the outer peripheral surface of the drum around which a tire member is wound, and a mounting surface for supporting a bent segment piece having an outer diameter smaller than the reference surface. The molding drum of the tire member according to claim 1.   Each segment is out of the reference where the outer surface of the main segment piece and the outer surface of the bent segment piece are continuous with substantially the same outer diameter while maintaining the overlap between the main segment piece and the bent segment piece. 3. The tire member forming drum according to claim 1, wherein the tire member is at least expanded and contracted between a diameter state and a 2 inch expanded state having an outer diameter that is 2 inches larger than the reference outer diameter state. The molding drum for a tire member according to claim 1 or 2, wherein the segments are equally distributed in a tire circumferential direction and satisfy the following formula (1).
Ls> 50.8π / n (1)
(Where π is the circularity ratio, n is the total number of segments per drum, Ls is the non-reference length where the outer surface of the main segment piece and the outer surface of the bent segment piece are substantially the same outer diameter) (Overlapping length in the circumferential direction (mm) in the radial state.)

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