JP2018199302A - Molding drum - Google Patents

Abstract

To provide a molding drum capable of filling a gap between segments with a small power.SOLUTION: The invention relates to a molding drum around which an unvulcanized rubber sheet is wound to form a cylindrical rubber member. The drum includes a central shaft 2, and a drum main body 3 having a cylindrical outer peripheral surface. The drum main body 3 includes a plurality of segments 5 arranged in the circumferential direction of the drum, driving means 6 for moving each segment 5 outward in the radial direction of the drum to substantially enlarge the outer circumferential surface, and a sheet-shaped member 10 that connects the segments 6 adjacent to each other in the circumferential direction of the drum. The sheet-shaped member 10 expands in the circumferential direction of the drum as the diameter of the segment 5 increases, and fills at least a part of the gap between the segments 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a forming drum for forming a cylindrical rubber member by winding an unvulcanized rubber sheet.

  For example, Patent Document 1 below proposes a molding drum for forming a cylindrical rubber member by winding an unvulcanized rubber sheet. The molding drum includes a drum body having an outer peripheral surface around which the rubber sheet is wound. The drum body includes a plurality of segments arranged in the circumferential direction of the drum and driving means for moving these segments outward in the drum radial direction. In the molding drum, the cylindrical outer peripheral surface of the drum main body can be substantially expanded in diameter while forming a gap between the segments as each segment moves outward in the drum radial direction.

  In the molding drum, a cylindrical rubber band is disposed on the outer peripheral surface of the drum body in order to prevent a rubber member from entering a gap between segments. However, since such a rubber band tightens the entire circumference of the drum body, it tends to hinder movement of each segment outward in the drum radial direction. For this reason, every time the diameter of the drum body is increased, a large power is required.

JP-A-9-99496

  The present invention has been devised in view of the above circumstances, and has as its main object to provide a molding drum that can fill the gaps between segments with a small amount of power.

  The present invention is a molding drum for forming a cylindrical rubber member by wrapping an unvulcanized rubber sheet, and is arranged on the outer side in the drum radial direction of the central axis and the central axis, and A drum body having a cylindrical outer circumferential surface for winding the rubber sheet, the drum body moving the plurality of segments arranged in the drum circumferential direction, and moving the segments outward in the drum radial direction. Drive means that substantially expands the outer peripheral surface, and a sheet-like member that connects the segments adjacent in the drum circumferential direction, the sheet-like member in the drum circumferential direction as the diameter of the segment increases At least part of the gap between the segments.

  In the molding drum of the present invention, it is preferable that the sheet-like member is an elastic body.

  In the molding drum of the present invention, it is desirable that the sheet-like member is arranged so that tension along the circumferential direction of the drum acts in a state where each segment is expanded in diameter.

  In the molding drum of the present invention, it is preferable that the sheet-like member is arranged so as to have an outer diameter substantially the same as an outer diameter of the segment in a state where the diameter of each segment is expanded.

  In the molding drum of the present invention, each of the segments includes a segment main body curved in an arc shape, and a holding portion that is formed on the inner peripheral surface side of the segment main body in the drum radial direction and holds the end of the sheet-like member It is desirable to include.

  In the molding drum of the present invention, it is desirable that the end portion of the segment body in the drum circumferential direction is tapered in a cross section orthogonal to the drum axis direction.

  In the molding drum of the present invention, it is preferable that the end of the segment body in the drum circumferential direction is rounded in an arc shape in a cross section orthogonal to the drum axis direction.

  In the molding drum of the present invention, it is preferable that the sheet-like member is disposed so as to be accommodated inside the segments in the drum radial direction before each segment is expanded.

  The molding drum of the present invention includes a sheet-like member that connects adjacent segments in the drum circumferential direction. The sheet-like member expands in the drum circumferential direction along with the diameter expansion of the segment, and can fill at least a part of the gap between the segments. Therefore, the present invention can expand the diameter of the drum body with small power.

It is a top view of the drum for molding of one embodiment of the present invention. (A) is a cross-sectional view of the forming drum when the diameter of the drum main body is the smallest, and (b) is a cross-sectional view of the forming drum when the diameter of the drum main body is the largest. (A) is an expanded sectional view of the sheet-like member of FIG. 2, (b) is an enlarged sectional view of the sheet-like member of FIG. It is an expanded sectional view of a segment. It is an expanded sectional view of the segment of other embodiments of the present invention. (A) And (b) is an expanded sectional view of a part of drum body of other embodiments of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a plan view of the molding drum 1 of the present embodiment. As shown in FIG. 1, the molding drum 1 is used for winding a non-vulcanized rubber sheet to mold a cylindrical rubber member. The molding drum 1 of the present embodiment is used, for example, to mold a cylindrical tire member, and more specifically, to mold a cylindrical raw tire base. The raw tire base is shaped in a later step to become a toroidal raw tire. A pneumatic tire can be manufactured by vulcanization-molding this raw tire. However, the present invention is not limited to such an embodiment.

  The molding drum 1 of the present embodiment includes a central shaft 2 and a drum body 3.

  For example, the central shaft 2 is rotatably supported. A known device is used as the device for supporting the central shaft 2 and is omitted in FIG. For example, the central shaft 2 of the present embodiment is supported in a cantilevered manner on one side in the drum axial direction.

  The drum body 3 is disposed radially outward of the central shaft 2 and has a cylindrical outer peripheral surface for winding a rubber sheet. The drum body 3 may be in any shape as long as a desired substantially cylindrical rubber member can be obtained by winding a rubber sheet, and is not limited to a perfect circular cross section.

  2A and 2B are cross-sectional views orthogonal to the central axis 2 of the molding drum 1. As shown in FIGS. 2A and 2B, the drum main body 3 includes a plurality of segments 5, a driving unit 6, and a sheet-like member 10.

  The segments 5 are arranged in the drum circumferential direction and constitute a cylindrical outer peripheral surface 3 s of the drum body 3. For this reason, each segment 5 has an arcuate outer surface in the cross section. The number of segments 5 is desirably 8 to 16, for example, and is 12 in this embodiment.

  The driving means 6 is provided, for example, inside each segment 5 in the drum radial direction. The driving means 6 is connected to each segment 5 and can move each segment 5 outward or inward in the drum radial direction. For example, an air cylinder or an actuator is used as the driving unit 6. By the driving means 6, the outer peripheral surface 3s of the drum body 3 can be substantially enlarged or reduced in diameter. FIG. 2A shows a state where the drum body 3 is most contracted, and FIG. 2B shows a state where the drum body 3 is expanded most.

  The sheet-like member 10 connects adjacent segments 5 in the drum circumferential direction. The sheet-like member 10 of this embodiment is connected to the inner surface side of the segment 5 in the drum radial direction, for example. Moreover, the sheet-like member 10 is connected to the edge part of the drum circumferential direction of the segment 5, for example.

  FIG. 3A shows an enlarged cross-sectional view of the sheet-like member 10 of FIG. FIG. 3B shows an enlarged cross-sectional view of the sheet-like member 10 of FIG. As shown in FIG. 3A, the sheet-like member 10 is disposed so as to be housed inside the segments 5 in the drum radial direction before each segment 5 is expanded.

  As shown in FIG. 3B, the sheet-like member 10 expands in the drum circumferential direction as the diameter of the segment 5 increases, and can fill at least part of the gap between the segments 5. Therefore, according to the present invention, the diameter of the drum body 3 can be increased with a small power. Thereby, for example, the power consumption when moving the drum body 3 can be reduced. Further, since the sheet-like member 10 fills the gap, for example, the rubber member is supported almost continuously from the inside, and the roundness thereof can be increased.

  The sheet-like member 10 has at least flexibility that can be deformed as described above in accordance with the operation of the segment 5. The sheet-like member 10 is preferably an elastic body, and more preferably, for example, a rubber member. The sheet-like member 10 of the present embodiment is constituted by, for example, a rubber member containing butyl rubber that is resistant to expansion and contraction. However, the sheet-like member 10 is not limited to such an aspect.

  The sheet-like member 10 is desirably arranged so that tension along the circumferential direction of the drum acts in a state where each segment 5 is expanded in diameter. As a result, the rubber member to be molded can be reliably prevented from entering the gap between the segments 5, and as a result, the roundness of the cross-sectional shape of the rubber member is increased.

  The sheet-like member 10 is desirably arranged so as to have an outer diameter substantially the same as the outer diameter of the segment 5 in a state where the diameter of each segment 5 is expanded. The above aspect includes an aspect in which the outer surface of the sheet-like member 10 is an ideal arc surface obtained by virtually extending the outer surface of the segment 5 in the drum circumferential direction. In addition, the aspect in which the outer surface of the sheet-like member 10 is arranged closer to the ideal arc surface than the virtual straight line connecting the end 5e of the one segment 5 and the end 5e of the other segment 5 is also possible. Shall be included. Thereby, the roundness of the cross-sectional shape of the rubber member is further increased. Therefore, the molding drum 1 of the present embodiment is useful for manufacturing a pneumatic tire excellent in uniformity.

  The sheet-like member 10 desirably has a length in the drum axial direction that is larger than that of the rubber member to be molded, for example. In a more desirable mode, the sheet-like member 10 has a length in the drum axial direction substantially equal to the segment 5. Thereby, it can suppress that a rubber member enters into the clearance gap between segments over the whole drum axial direction of a rubber member.

  The sheet-like member 10 includes, for example, a pair of first portions 11 that are respectively held by the segments 5 on both sides in the drum circumferential direction, and a second portion 12 disposed therebetween.

  For example, the first portion 11 has a thickness that does not cut even when the sheet-like member 10 is pulled by the segment 5. The thickness of the first portion 11 is preferably, for example, 1.0 to 5.0 mm.

  The second portion 12 can fill a gap between the segments 5 when the diameter of the segments 5 is increased. The second portion 12 includes, for example, a contact portion 13 that contacts the segment 5 when the diameter of the segment 5 increases, and an outer peripheral portion 14 that constitutes a part of the outer peripheral surface of the drum body 3 when the diameter of the segment 5 increases. Including.

  For example, it is desirable that the thickness of the contact portion 13 gradually increase toward the outer peripheral portion 14 side. For example, the outer peripheral portion 14 preferably has a constant thickness larger than that of the first portion 11 and the contact portion 13. With the above-described configuration, the second portion 12 of the present embodiment is a pneumatic tire that has an outer diameter of the outer peripheral portion 14 that is substantially the same as the outer diameter of the segment 5 when the segment 5 is expanded. Can be molded.

  FIG. 4 shows an enlarged sectional view of the segment 5. As shown in FIG. 4, each segment 5 includes a segment body 16 and a holding portion 17.

  The segment body 16 can be curved in an arc shape and constitute the outer peripheral surface of the drum body 3. The holding portion 17 is formed on the inner peripheral surface side of the segment main body 16 in the drum radial direction, for example. Further, for example, one holding portion 17 is provided on each side of the segment body 16 in the drum circumferential direction. The holding portion 17 can hold the end portion of the sheet-like member 10.

  For example, the holding unit 17 holds the sheet-like member 10 by sandwiching at least a part of the first portion 11 of the sheet-like member 10 between the segment body 16. In a desirable mode, the holding part 17 includes, for example, a first holding part 18 and a second holding part 19. The first clamping unit 18 has, for example, a substantially U-shaped cross section and sandwiches the end of the first portion 11. The 2nd clamping part 19 has pinched | interposed parts other than the edge part of the 1st part 11, for example. For example, the second sandwiching portion 19 of the present embodiment sandwiches the sheet-like member 10 between a part of the first sandwiching portion 18 and the segment body 16. Such a holding | maintenance part 17 can prevent effectively that the sheet-like member 10 remove | deviates.

  The end of the segment body 16 in the circumferential direction of the drum is preferably tapered with a thickness that gradually decreases toward the outer end. Thereby, the level | step difference of the outer surface of the segment 5 and the outer surface of the sheet-like member 10 becomes small.

  FIG. 5 is an enlarged cross-sectional view of the segment 5 according to another embodiment of the present invention. As shown in FIG. 5, the end 16e of the segment body 16 of this embodiment is rounded into an arc shape. Such a segment main body 16 can prevent the sheet-like member 10 from being damaged by the end portion, and as a result, the durability of the sheet-like member 10 is enhanced.

  6A and 6B are enlarged cross-sectional views of a part of a drum body 3 according to another embodiment of the present invention. As shown in FIGS. 6A and 6B, in this embodiment, a sheet support portion 20 for supporting the sheet-like member 10 is provided inside the drum body 3.

  As illustrated in FIG. 6A, the sheet support portion 20 is disposed, for example, on the inner side in the drum radial direction of the sheet-like member 10. The sheet support portion 20 includes a tip portion 21 and an actuator 22. The tip portion 21 has, for example, a flat outer surface that comes into contact with the sheet-like member 10. The actuator 22 can move the tip 21 in the drum radial direction. When each segment 5 has a reduced diameter, the actuator 22 does not contact the sheet-like member 10 with the tip 21 but is positioned on the inner side in the drum radial direction than this.

  As shown in FIG. 6B, when each segment 5 expands in diameter, the actuator 22 moves the distal end portion 21 outward in the drum radial direction. The outer surface of the distal end portion 21 can contact and support the sheet-like member 10. The sheet support portion 20 can suppress the rubber member from bending inward in the drum radial direction in the gap between the segments 5, and can further increase the roundness of the cross-sectional shape of the rubber member.

  As mentioned above, although the molding drum of one embodiment of the present invention was explained in detail, the present invention is not limited to the above-mentioned specific embodiment, and can be carried out by being changed to various aspects.

As an example, a molding drum having the above-described configuration was prototyped. As Comparative Example 1, a molding drum in which a sheet-like member that fills the gaps between the segments was not provided was manufactured. As Comparative Example 2, a molding drum in which the sheet-like member was not disposed and a rubber band was wound around the entire circumference of the drum body was manufactured as a prototype. Using each drum, 50 235 / 45R18 pneumatic tires were produced. For each drum, the power consumption when expanding the diameter of the drum body and the uniformity of the pneumatic tire were measured. The common specifications and measurement methods for each drum are as follows.
Number of drum segments: 12
Drum circumference: 1700mm

<Power consumption when expanding the drum body>
For each drum, the average power consumption when expanding the drum body was measured. A result is an index | exponent which sets the comparative example 1 to 100, and shows that the said power consumption is so small that a numerical value is small.

<Uniformity>
For the pneumatic tire, low-speed RFV (radial force variation) and high-speed RFV, which are fluctuation components of force in the tire radial direction during rotation, were measured under the following conditions. The low-speed RFV and the high-speed RFV were measured in accordance with JASO C607: 2000 “Automotive tire uniformity test method” using a tire uniformity tester. The low speed RFV is an RFV when traveling at 60 km / h. The high-speed RFV is an RFV when traveling at 120 km / h. Moreover, the average value of each RFV of each manufactured tire was calculated for each drum. A result is an index | exponent which sets the average value of the comparative example 1 to 100, and shows that the uniformity of the manufactured tire is so favorable that a numerical value is small.
Wearing rim: 18 × 8J
Tire internal pressure: 200kPa
Longitudinal load: 5000N
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the molding drum of the example could expand the diameter of the drum body with a small power. Moreover, it has confirmed that the molding drum of an Example is useful for manufacturing the pneumatic tire excellent in uniformity.

2 Central axis 3 Drum body 5 Segment 6 Driving means 10 Sheet-like member

Claims (8)

A molding drum for forming a cylindrical rubber member by winding an unvulcanized rubber sheet,
A central axis, and a drum body that is disposed outward of the central axis in the drum radial direction and has a cylindrical outer peripheral surface for winding the rubber sheet;
The drum body is adjacent to the plurality of segments arranged in the drum circumferential direction, and driving means for moving the segments outward in the drum radial direction to substantially expand the outer peripheral surface in the drum circumferential direction. Including a sheet-like member connecting the segments,
The sheet-like member expands in the drum circumferential direction along with the diameter expansion of the segment, and fills at least a part of the gap between the segments.
Drum for molding.   The forming drum according to claim 1, wherein the sheet-like member is an elastic body.   The molding drum according to claim 2, wherein the sheet-like member is arranged so that a tension along a circumferential direction of the drum acts in a state where the diameter of each segment is expanded.   The forming drum according to any one of claims 1 to 3, wherein the sheet-like member is arranged to have an outer diameter substantially the same as an outer diameter of the segment in a state where the diameter of each segment is expanded. .   Each of the segments includes a segment body that is curved in an arc shape, and a holding portion that is formed on an inner peripheral surface side of the segment body in the drum radial direction and holds an end portion of the sheet-like member. The molding drum according to any one of the above.   6. The forming drum according to claim 5, wherein an end portion of the segment body in the drum circumferential direction is tapered in a cross section orthogonal to the drum axis direction.   6. The forming drum according to claim 5, wherein an end of the segment body in the drum circumferential direction is rounded in an arc shape in a cross section orthogonal to the drum axis direction.   The molding drum according to any one of claims 1 to 7, wherein the sheet-like member is disposed so as to be accommodated inside the drum in the drum radial direction before each segment is expanded in diameter. .

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