Method for producing a drive belt with a fabric composite material cover

Abstract

Method for producing a drive belt, preferably a toothed belt, with a layer of fabric composite material on its back and / or its drive side, wherein the fabric composite material has a fabric layer embedded in a matrix of elastomeric material, characterized in that the fabric layer and the elastomeric material are introduced into a gap between a belt and a cylindrical forming wheel and are formed between the belt and the forming wheel at a temperature below the vulcanization temperature to form a composite material, wherein the belt wraps around the forming wheel over a wrap angle under pressure, wherein the temperature during the forming process between the belt and the forming wheel does not exceed 150°C.

Description

[0001] The invention relates to a method for producing a drive belt, preferably a toothed belt, with a layer of fabric composite material on its back side and / or its drive side, wherein the fabric composite material has a fabric layer embedded in a matrix of elastomeric material.

[0002] The matrix typically refers to the material in composite materials into which other components are embedded. In this field, "rubberizing" typically refers to the incorporation of textiles into rubber mixtures or polymer preparations. The term "coating" here refers to the application of a fabric composite material to the surface of an object, such as a drive belt, and the appropriate bonding of the fabric composite material to the object's surface. The term "mixture" is used here to refer to any mixtures of or with rubber and / or other polymers.

[0003] Drive belts, such as V-belts, multi-V-belts, or timing belts, are often equipped with fabric layers on their outer surfaces, which significantly improve the friction and wear conditions between the drive belt and drive pulleys during operation. Such fabrics are typically treated with various rubber or other polymer preparations to improve adhesion, wear protection, and oil resistance.

[0004] A variety of processes are used to produce these fabrics. One manufacturing option is to immerse the fabric in a rubber solution / rubber compound solution or adhesive solution. However, this requires a relatively complex process of first preparing the corresponding solution, and subsequent, considerable energy is required to dry the fabric. Furthermore, the processing volume is limited by the amount of solution.

[0005] A relatively complex exhaust gas purification process is also required because the solutions contain a solvent. Furthermore, the evaporation of the solvents leaves pores in the textile composite or composite material, posing a risk that the fabric will not be completely filled. It is also not always guaranteed that all solvents will evaporate from the matrix-forming material and not remain in the matrix.

[0006] Due to the process, textiles with high longitudinal extensibility cannot be used. This refers to textiles that exhibit more than 50% elongation at a tension of 100 N, measured using a 5 cm wide textile strip. Textiles with high longitudinal extensibility, also known as longitudinal stretch textiles, are produced, for example, by texturing the warp threads, for example, using the false-twist process, or by using elastic threads.

[0007] Furthermore, in the processes listed above, only one material per operation is available as a matrix former for the fabric / composite material.

[0008] Similar disadvantages arise both with spreading, which usually involves spreading a polymer or rubber paste or a paste based on polymer or rubber mixtures, and with calendering. Calendering is a process in which a mixture plate or mixture mat is pressed into another fabric or bonded to the latter with the help of a roller. In the present case of the production of fabric composite materials, this would be a mixture plate that is worked into the fabric layer with a roller. A disadvantage of calendering can be that the surface contact of the mixture plate does not fill the textile or fabric layer well enough, or that the penetration depth of the mixture into the fabric layer is too low, depending of course on the viscosity of the mixture.

[0009] Another possible method is "friction molding," in which a rubber or polymer mixture is heated by mechanical rolling, then kneaded while hot, and then driven into the textile using a roller. The disadvantage of this method is that the application quantity is limited, and only one material can be applied per step. Here, too, it is possible that the matrix material is only driven into the topmost textile layer, resulting in filling defects. Furthermore, the textile or fabric layer is naturally subjected to significant tensile stress, so textiles with high longitudinal extensibility are rarely used here.

[0010] The object of the invention was therefore to provide a method for producing a drive belt with a layer of fabric composite material on its back and / or its drive side, which does not have the disadvantages mentioned, ensures a pore-free and solvent-free matrix for the composite material, which allows several materials to be introduced in one operation, reduces solvents and which simplifies the manufacturing process in terms of machine and personnel expenditure.

[0011] This problem is solved by the features of the main claim. Further advantageous embodiments are disclosed in the subclaims.

[0012] In the method according to the invention, the textile or fabric layer and the elastomeric material are introduced into a gap between a belt and a cylindrical forming wheel and formed into a composite material between the belt and forming wheel at a temperature below the vulcanization temperature, wherein the belt wraps around the forming wheel at a wrap angle under such a pressure that the elastomeric material penetrates the textile or fabric layer so that complete penetration occurs and the yarns of the textile or fabric layer are completely integrated into the elastomeric material. The temperature during the forming process between the belt and forming wheel does not exceed 150°C. By keeping the temperature between the belt and forming wheel below the stated limits during the production of the composite material, it is possible to reliably prevent noticeable vulcanization effects from occurring during the production of the composite materials.

[0013] Surprisingly, the inventive process even bonds textiles with high longitudinal elongation (longitudinal stretch textiles) to, for example, a rubber or polymer matrix in such a way that the ability to stretch longitudinally is essentially retained in the composite material, with the textile completely embedded in the matrix, i.e., filled with the matrix material. The wrap angle around the forming wheel is adjustable depending on the process and is typically more than 180°.

[0014] The advantage of a flat fabric composite material manufactured in this way, e.g., a rubberized fabric layer, is that all yarns and tensile strands are protected by surrounding elastomeric material and integrated into the matrix. Drive belts equipped with such a fabric layer also exhibit particularly high adhesion between this fabric layer and the remaining material. For example, in timing belts that run in warm oil, the inventive manufacturing process protects the textile or fabric layer so well that the running time and service life in such aggressive environments are significantly increased.

[0015] According to a further aspect, the advantageous pressure here is in a range of 2 to 6 bar. The penetration of the elastomeric material into the yarns of the textile or fabric layer is particularly effective here.

[0016] According to a further advantageous embodiment, the temperature between the belt and the forming wheel during the forming process does not exceed 100°C, which is particularly important for heat-sensitive components in the matrix. Components that already exhibit more than 10% crosslinking conversion at a process temperature of 100°C are referred to as "heat-sensitive." By keeping the temperature between the belt and the forming wheel below these limits during the production of the composite material, noticeable vulcanization effects can be reliably prevented from occurring during the production of the composite materials.

[0017] The process according to the invention can be implemented particularly easily by using existing, already known production equipment, which can be adapted to the claimed process by simply modifying its production process. Advantageously, the textile or fabric layer and the elastomer material can be placed between a belt and a cylindrical forming wheel of a rotary vulcanization device (AUMA®) and formed there into a composite material. The temperature control and contact pressure of the belt must then be adjusted so that vulcanization does not occur, but complete penetration of the fabric is nevertheless achieved.

[0018] Such rotational vulcanization devices are disclosed, for example, in DE 19 31 972 A, DE 26 55 025 C2 and DE 10 2013 102 148 A1, although these describe a rotational vulcanization process which uses extruded base material. To produce an elastic traction device / drive belt blank, tension members run into the extruded, still warm and relatively viscous material in an outlet nozzle during extrusion. The resulting still viscous material, including the tension members, is formed into the finished traction device between a belt and a cylindrical forming wheel, with heat being removed, and vulcanized, with the belt wrapping around the forming wheel under pressure over a wrap angle. As already stated above, when using such a system for the process according to the invention, the temperature control and the supply of elastomer matrix material must be designed such that the composite material does not vulcanize.However, the belt running under pressure on a forming wheel is important here and can be used to ensure a secure bond between fabric or textile and elastomeric material.

[0019] DE 32 35 740 A1 discloses the production of endless idler belts intended to hold or support drive belts, conveyor belts, or other elongated tension elements provided with reinforcing elements during production and vulcanization. The resulting idler belts are intended as part of a vulcanization device, in particular a device for continuous vulcanization.

[0020] US Pat. No. 3,247,038 A discloses a process for manufacturing traction devices. These can be drive belts, straps, or conveyor belts. Vulcanization of the traction devices takes place in a stretched state. This occurs either in spaced clamps that hold the traction device under tension, or by vulcanizing the traction device using a heated vulcanization drum and a forming belt, which is held under tension by rollers.

[0021] An advantageous development is that the elastomeric material is a polymer mixture, in particular a rubber mixture, preferably a solvent-free polymer mixture or rubber preparation / rubber mixture. This allows the use of easily manufactured mixtures that contain no solvents. Solvents, which are actually only required for the bonding process—i.e., only to reduce the viscosity for introducing the elastomeric material into and between the yarns of the fabric layer—can then be dispensed with. This not only increases occupational safety but is also extremely desirable for environmental protection reasons.

[0022] A further advantageous design involves the elastomeric material being inserted as a sheet between the belt and the cylindrical forming wheel, with the sheet being inserted on one or both sides of the textile or fabric layer. Such sheets can be manufactured in any way as precursor material and are very easily integrated into the manufacturing process.

[0023] Another advantageous design involves inserting multiple layers of elastomeric material or textile or fabric between the belt and the cylindrical forming wheel. This allows the composition and thickness of the composite material to be easily adapted to the further requirements of production and / or subsequent operation.

[0024] A textile or fabric layer with a textile that stretches more than 50% at a tension of 100 N in the longitudinal direction of the covering, measured on a textile strip with a width of 5 cm, is particularly suitable for covering drive belts. Even with more complex shapes, such as those found in timing belts or V-ribbed belts, such a drive belt can be easily manufactured or covered with a layer of a matrix-bonded longitudinal stretch textile and thus a stretchable composite material.

Claims

[1] Method for producing a drive belt, preferably a toothed belt, with a layer of fabric composite material on its back and / or its drive side, wherein the fabric composite material has a fabric layer embedded in a matrix of elastomeric material, characterized by that the fabric layer and the elastomeric material are introduced into a gap between a belt and a cylindrical forming wheel and formed between the belt and the forming wheel at a temperature below the vulcanization temperature to form a composite material, wherein the belt wraps around the forming wheel over a wrap angle under pressure, wherein the temperature during the forming process between the belt and the forming wheel does not exceed 150°C. [2] Method according to claim 1, characterized by that the belt wraps around the forming wheel under a pressure of 2 to 6 bar. [3] Method according to claim 1 or 2, characterized bythat the temperature between the strip and the forming wheel does not exceed 100 °C during the forming process. [4] Method according to one of claims 1 to 3, wherein the elastomeric material is a polymer mixture, in particular a rubber mixture, preferably a solvent-free rubber preparation / rubber mixture. [5] Method according to one of claims 1 to 4, in which the elastomeric material is introduced as a plate between the belt and the cylindrical forming wheel, the plate being introduced on one side or on both sides of the fabric layer. [6] Method according to one of claims 1 to 5, in which several layers of elastomeric material or fabric are introduced between the belt and the cylindrical forming wheel. [7] A method according to any one of claims 1 to 6, wherein the fabric layer and the elastomeric material are introduced between a belt and a cylindrical forming wheel of a rotary vulcanization device and formed there into a composite material. [8] A method for producing a drive belt according to claim 7, wherein the fabric layer in the fabric composite material comprises a textile with more than 50% elongation at a tension of 100 N in the longitudinal direction of the covering, measured on a textile strip with a width of 5 cm.