JP2006264204A - Method for manufacturing rubber structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a rubber structure which can be formed easily and at a low cost. <P>SOLUTION: In a forming stage of the rubber structure, rubber and cords are laminated on the outside of a cylindrical airbag to form a cylindrical unvulcanized formed body. In a vulcanization stage of the formed body, the airbag is pressurized in a vulcanization mold to be inflated to expand diameter of the formed body outside thereof, and the formed body is vulcanized and formed while the airbag and the formed body are made shrunk. As a result, forming and vulcanizing of a rubber structure can be performed by using one airbag and the manufacturing process of the rubber structure can be simplified by virtue of unification of forming and vulcanizing. In other words, conventional disassembling labor of a divided core type drum is dispensable because the airbag is mounted on the formed body intact from the forming of the rubber structure through the vulcanization. Further, good quality rubber structure can be provided by preventing crimple on the product from occurring because the insertion of the airbag at the time of the vulcanization becomes unnecessary and shaping also becomes unnecessary. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a method of manufacturing a rubber structure such as a diaphragm used for an air spring.

    Patent Document 1 discloses a method of vulcanizing by putting an airbag inside when a corded cylindrical rubber structure is vulcanized. Patent Document 2 discloses a long air spring having a relatively long tube length L relative to a tube diameter D, that is, a large L / D.

  Conventionally, when manufacturing a rubber structure such as a diaphragm of an air spring or a tire, molding and vulcanization are performed separately. First, at the time of molding, an unvulcanized rubber molded body is formed by using a cylindrical drum and laminating inner rubber, two or four layers of reinforcing Suda Records, and a cover rubber sheet around the outer circumferential surface in a cylindrical shape. . Then, at both ends of the unvulcanized rubber molded body, the wound cord / rubber sheet is folded at the bead wire portion to complete the unvulcanized rubber molded body.

At this time, since both ends of the wound cylindrical molded body have a diameter smaller than that of the main body of the molded body, the cylindrical drum is disassembled after the molding is completed, and the molded body is taken out. Then, the unvulcanized rubber molded body taken out is inserted into a product mold, an air bag is inserted therein, high pressure air or the like is supplied to the air bag and pressurized from the inside to vulcanize. Yes.
Japanese Patent Publication No. 5-237848 Japanese Patent Laid-Open No. 2003-202045

However, the conventional method for producing a rubber structure has the following problems.
(1) Since the cylindrical molded body wound around the molding drum is smaller in diameter than the main body at both ends, a core drum is required to disassemble the cylindrical molding drum after the molding is completed and take out the molded body. It becomes. Therefore, there is a problem that it takes time to assemble and disassemble the drum.
(2) The airbag used at the time of vulcanization of the molded body is a dedicated airbag having a shape slightly smaller than the mold so that the rubber structure (product) is along the mold and a shape close to the product mold. Necessary. Therefore, it is necessary to prepare a mold suitable for a dedicated airbag, and there is a disadvantage that the cost of the bag mold increases.
(3) Since the airbag has an outer diameter larger than that of the molded body and has a shorter cylinder length than the molded body, it is necessary to shape a thin unvulcanized rubber molded body. Skilled skills and high-precision equipment are required.
(4) When the airbag is inserted into the unvulcanized molded body, rubbing occurs between the unvulcanized rubber molded body and the airbag, and there is a possibility that wrinkles and streaks enter the rubber structure (product).
(5) Since the airbag is a simple rubber, when the airbag is pressurized, it tends to be spherical from the center. For this reason, cord density changes and thickness fluctuations increase at the center, making it difficult to produce a rubber structure of good quality.

  In view of the above problems, an object of the present invention is to provide a method for producing a rubber structure that is easy to mold and can be produced at low cost.

  In order to achieve the above object, the present invention is a method for producing a cylindrical rubber structure, which is formed by laminating rubber and a cord on the outside of a cylindrical airbag. The molded body is inserted into a product mold while the molded body is held by the airbag, and the airbag is pressurized and inflated to expand the outer diameter of the molded body. The molded body is contracted and vulcanized.

  According to the above manufacturing method, the rubber structure can be molded and vulcanized using one airbag, and the manufacturing process of the rubber structure can be simplified by unifying the molding and vulcanization. . In other words, since the airbag is carried out while the rubber structure is molded to vulcanized, it is not necessary to disassemble the split-core drum as in the prior art, and there is no need to insert the bag during vulcanization. Furthermore, since shaping is not required, generation of product defects can be prevented and a high-quality rubber structure can be provided.

  In the rubber structure molding step, in addition to forming the outer shape of the airbag in accordance with the desired shape of the molded body, the cylindrical airbag can be inflated by pressurization to match the outer shape of the molded body. . Thereby, an airbag can be shape | molded by simple cylindrical shape, and a rubber structure can be manufactured with a very cheap airbag.

  In the manufacturing method as described above, in the vulcanization stage of the molded body, the airbag is further pressurized and inflated in the vulcanization mold while the unvulcanized molded body is held in the airbag. Thus, the outside of the molded body is expanded, and the airbag and the molded body are contracted to vulcanize the molded body.

  At this time, if an air bag molded with a simple rubber is used, the molded body tends to be spherical from the center without expanding into the desired cylindrical shape at the molding / vulcanization stage of the molded body. First, the central portion is enlarged, and there is a possibility that the code density, the cord angle, and the thickness of the molded body may be uneven.

  In order to solve this problem, it is preferable to use the one in which the cord is embedded and reinforced in the interior of the airbag, and to inflate it into a cylindrical shape in the molding / vulcanization stage of the molded body. The corded airbag can also apply a high internal pressure during vulcanization of the rubber structure, and a rubber structure having a desired shape can be manufactured by bringing the airbag into close contact with the rubber structure.

  As such a cord embedding structure, a cord similar to a molded body is arranged in a bias in an airbag, and the cord of the airbag is preliminarily set so that the cord angle of the airbag is close to 55 degrees when the molded body is vulcanized. Set the corner.

  When the airbag as described above is used, in the molding step of the rubber structure, the airbag is inflated in a cylindrical shape with both ends of the airbag fixed, and rubber and a cord are laminated on the outside, and the molded body In this vulcanization stage, the airbag is moved inward in the axial direction (cylinder length direction) while the airbag is further inflated by further pressing the airbag in the free state.

  When the airbag is inflated with both ends of the airbag fixed, the cord angle of the cord in the airbag does not change, and the cylinder diameter of the airbag increases only by the cord being stretched by pressurization. On the other hand, if pressure is applied without fixing both ends, the diameter of the inner cord increases while the cord angle changes, and as a result, the cylinder length of the airbag is reduced. In this case, the extension of the inner cord itself is small, and the cord angle is changed to increase the diameter.

  In manufacturing the rubber structure as described above, a plurality of rubber structures can be molded at the same time. That is, after connecting a plurality of airbags in the axial direction and wrapping and laminating a cord and rubber on the outside of the plurality of airbags to form a rubber sheet body, The rubber sheet body is cut and separated, a bead is wound around the end portion of the separated rubber sheet body, and folded back from the bead as a starting point to form a cylindrical unvulcanized rubber molded body. According to the above manufacturing method, a plurality of molded bodies can be molded simultaneously, and the molding time is shortened.

  The rubber structure as described above can be applied to any cylindrical shape regardless of its length. However, the rubber structure has a large diameter and a large contraction during vulcanization and is difficult to be incorporated into a vulcanization mold. It is preferable to apply to a rubber structure of a scale. The long length in this case means that the ratio (L / D) of the cylinder length (L) to the cylinder diameter (D) of the rubber structure is 1.5 or more.

  The rubber structure can be applied to manufacture various cylindrical bodies such as a rubber tank and a bag, and in particular, can be applied to manufacture a long diaphragm used for an air spring.

  As described above, according to the method for manufacturing a rubber structure according to the present invention, the rubber structure can be molded and vulcanized by using one airbag, and the rubber structure is unified by molding and vulcanization. The manufacturing process can be simplified.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of an air spring equipped with a diaphragm manufactured by the manufacturing method of the present invention. As shown in FIG. 1, the air spring 1 is provided with a cylindrical diaphragm 4 folded between the upper surface plate 2 and the piston 3. The upper surface plate 2 and the piston 3 are input by vibration input. A relative displacement along the axial direction occurs between the two.

  FIG. 2 is a partially cutaway cross-sectional view of the diaphragm. In FIG. 2, the right half of the center line represents the side surface, and the left half of the center line represents the vertical section. As shown in FIG. 2, the diaphragm 4 is formed in a substantially cylindrical shape from a small-diameter cylindrical portion 4a at both ends and a central cylindrical portion 4b continuous therewith. The diaphragm 4 has a laminated structure of an inner rubber, a two-ply reinforcing cord, and a cover rubber. The diaphragm 4 is a long cylindrical body having a ratio (L / D) of the cylinder length L to the cylinder diameter D of 1.5 or more. In this embodiment, L / D = 3.0.

  The reinforcement cord is a nylon cord with rubber topping to a desired thickness. One ply of this reinforcement cord is attached to a bias whose cord direction is oblique to the axial direction, and the second ply reinforcement cord is attached. Paste to reverse bias. In this embodiment, it is pasted with a bias of 38.5 degrees. Reinforcing bead portions 6 formed by wrapping steel wire rods in a ring shape are embedded in both ends of the diaphragm 4.

  FIG. 3 is a schematic process diagram illustrating a manufacturing process of a diaphragm as a rubber structure according to the present invention. Among the process diagrams of (a) to (f) in this figure, the figures after (c) show a cross-sectional view of the upper half of the production drum that is symmetric with respect to the center line, and a cross-section of the lower half is omitted. ing.

  The diaphragm manufacturing process will be described with reference to FIG. 3. As shown in the process diagram (a), a shaft-equipped pipe 11 is prepared, and rubber and a cord are laminated on the outer peripheral surface of the pipe 11 in the process (b). The airbag 13 is molded and vulcanized. Next, in the step (c), the bag fastening metal parts 12 are arranged at both ends of the pipe.

  In the next step (d), the inside of the airbag 13 is pressurized to obtain a cylindrical body having an enlarged diameter. At the time of this pressurization, the fastening fittings 12 at both ends are fixed, and the airbag 13 is kept cylindrical. At this time, as shown in FIG. 3D, a plurality of pipes 11 can be connected in succession to form a plurality of rubber structures at a time.

  FIG. 4 is a cross-sectional view showing a main part when a plurality of pipes 11 are connected continuously, and shows an upper half of the center line. As shown in FIG. 4, the connecting cylinder 17 is fitted and fixed to the end of the pipe 11, and bolts are fastened to the connecting holes 18 formed on one end side of the connecting cylinder 17 and the pipe 11. Make it continuous.

  For forming the rubber structure, first, an inner rubber sheet is wound around the outer peripheral surface of the airbag 13, a two-ply Suda record is wound around the outer surface at a constant angle, and a cover rubber sheet is wound around the outer surface. A rubber sheet body 14 continuous in the direction is formed on a plurality of continuous molding drums. Next, the rubber sheet body 14 is cut at the drum connecting portion. In the step (e), the bead 6 is wound around the cut ends, and the rubber sheet body 14 is folded back from the bead 6 as a starting point. Is molded.

  Next, in the step (f), the product mold 16 is incorporated outside the molded unvulcanized molded body 15, and the molded body 15 is compressed in the axial direction (while the overall length is shortened), and the air pressure inside the airbag is increased. Or it pressurizes with water pressure etc., and presses to the metal mold | die 16, expanding the molded object 15 in diameter. At this time, the entire length of the airbag itself is also compressed.

  FIG. 5 is a cross-sectional view showing a specific example of the product mold, in which the upper side from the center line shows a state before reduction, and the lower side from the center line shows a state after reduction. The product mold 16 includes a central cylindrical mold 16a and an end mold 16b, and the end mold 16b is movable in the axial direction from both sides of the cylindrical mold 16a. The end mold 16 b is inserted and bolted by the fastening bolt 19.

  Then, by applying an internal pressure in the airbag 13 and gradually increasing the pressure, the airbag 13 is inflated and the entire length of the airbag 13 is reduced. Along with this, the molded body 15 also expands and contracts, but at the same time, the end mold 16b is fitted to the cylindrical mold 16a by the fastening bolts 19 on both sides. If it does so, the molded object 15 expanded and shortened will be obtained.

  Then, vulcanization is performed while maintaining the expanded / reduced state of the molded body 15. For vulcanization, a hot platen press may be used, or can vulcanization may be performed. An example of the vulcanization time is 160 degrees and 30 minutes (excluding preheating time). After vulcanization, if the internal pressure of the airbag is removed, the airbag 13 is reduced in diameter to a simple cylindrical body as shown in FIG. Therefore, the product (rubber structure) can be easily removed and taken out.

  Thus, in the case of a rubber structure in which the ratio of the cylinder length L to the cylinder diameter D (L / D) is large and the product outer diameter is larger than the outer diameter of the unvulcanized rubber molded body, Although it is necessary to compress the entire length and increase the cord angle with respect to the axis (in FIG. 5, θ represents the cord angle of the molded body, and θ1 represents the cord angle after diameter expansion), A cylindrical rubber structure having a large diameter can be manufactured by compressing the entire length and simultaneously giving the airbag 13 an approximately equal compression amount.

  Here, the airbag 13 is arranged by adding a cord similar to that of the molded body to the bias and setting the cord angle in advance so that the cord angle is around 55 degrees, which is the most stable cord angle at the time of vulcanization. When vulcanizing, it shrinks together with the compact. The predetermined code angle is designed by calculation based on the ratio of the cylinder length L to the cylinder diameter D (L / D), but is usually set to 35 degrees to 45 degrees.

  Further, since the molded body 15 is expanded and contracted together with the airbag 13 and it is not necessary to apply a contracting force to the molded body itself, it is possible to prevent the molded body 15 from wrinkling. Naturally, this action is not spheroidizing like a rubber simple bag but cylindrical, so it is not partially expanded or compressed, but the entire expansion and contraction are uniform, making it an ideal cylindrical diaphragm Can be manufactured.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that many modifications and changes can be made within the scope of the present invention.

The longitudinal cross-sectional view which shows embodiment of the air spring with which the diaphragm illustrated as a rubber structure which concerns on this invention was mounted | worn Partial cutaway view of diaphragm Schematic process drawing for explaining a method for producing a rubber structure according to the present invention Sectional drawing which shows the connection state of several airbags Cross-sectional view of a specific vulcanization mold

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air spring 2 Top plate 3 Piston 4 Diaphragm 4a Small diameter cylinder part 4b Central cylindrical part 6 Bead part 11 Pipe 12 Fastening metal fitting 13 Air bag 14 Rubber sheet body 15 Molding body 16 Product metal mold | die 17 Connection cylinder 18 Connection hole 19 Fastening bolt

Claims (8)

A method for producing a cylindrical rubber structure, in which a cylindrical unvulcanized rubber molded body is molded by laminating rubber and a cord on the outside of a cylindrical airbag, and the molded body is used as an airbag. The product is inserted into the product mold while being held in place, and the airbag is pressurized and inflated to expand the diameter of the outer molded body, and the airbag and the molded body are reduced in length. A method for producing a rubber structure, comprising vulcanization. A method for producing a cylindrical rubber structure, in which a cylindrical airbag is inflated and a rubber and a cord are laminated on the outside thereof to form a cylindrical unvulcanized rubber molded body. Is inserted into the product mold while being held in the airbag, and the airbag is further pressurized and inflated to expand the outside molded body, and the airbag and the molded body are contracted. A method for producing a rubber structure, comprising vulcanizing the molded body. The method for producing a rubber structure according to claim 1 or 2, wherein an airbag having a cord embedded therein is used and inflated into a cylindrical shape in a molding step and a vulcanization step. The rubber according to claim 3, wherein the cord is arranged in a bias, and the cord angle of the airbag is set in advance so that the cord angle of the airbag is close to 55 degrees when the molded body is vulcanized. Manufacturing method of structure. At the rubber structure molding stage, both ends of the airbag are fixed, and rubber and cord are laminated on the outside to form an unvulcanized rubber molded body. At the vulcanization stage, both ends of the airbag are in a free state. The method for manufacturing a rubber structure according to claim 3 or 4, wherein the airbag is moved inward in the axial direction while inflating the airbag. The plurality of airbags are connected in the axial direction, and a rubber sheet body is formed by wrapping and laminating a cord and rubber on the outside of the plurality of airbags, and then the rubber is formed at the connection portion of the airbag. The sheet body is cut and separated, a bead is wound around the end of the separated rubber sheet body, and the sheet is folded back from the bead to form a cylindrical unvulcanized rubber molded body. A method for producing a rubber structure according to claim 1. The rubber structure according to any one of claims 1 to 6, wherein the rubber structure has a ratio (L / D) of a cylinder length (L) to a cylinder diameter (D) of 1.5 or more. Production method. The method for producing a rubber structure according to any one of claims 1 to 7, wherein the rubber structure is a diaphragm used for an air spring.

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