Method for producing gaskets

Abstract

The current invention relates to a method for producing gaskets comprising the steps of: providing an elastomer-bonded fiber sheet on a roller; slitting the elastomer-bonded fiber sheet into a continuous strip by pressing a blade against the roller, shaping the continuous strip into a spiral with a predetermined inner diameter, cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a gasket.

Description

[0001] METHOD FOR PRODUCING GASKETS

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method for producing gaskets.

[0004] BACKGROUND

[0005] In the manufacturing of gaskets, particularly those made from elastomer-bonded fiberboard materials, significant material waste and inefficiencies are prevalent. Traditional stamp-cutting methods, especially when producing large-diameter rings, result in considerable "stamp-cutting loss", which is the material wasted during the cutting process. This waste not only increases production costs but also has a negative environmental impact.

[0006] Additionally, conventional methods often involve multiple seams in the final gasket product, which can compromise the integrity and performance of the gasket. The challenge lies in developing a method that minimizes material waste, enhances production efficiency, and produces gaskets with minimal seams, thereby improving the overall quality and durability of the gaskets.

[0007] EP1800029 discloses a low stress to seal, unitary gasket tape that for use in form- in-place gaskets.

[0008] The aim of the invention is to provide a method which eliminates those disadvantages.

[0009] SUMMARY OF THE INVENTION

[0010] The invention addresses the problem of material waste, particularly in the stampcutting of large-diameter rings from fiberboard materials, by introducing a novel method for producing gaskets according to claim 1.

[0011] This method is designed to reduce waste and enhance efficiency. The process involves slitting a fiber sheet, preferably an elastomer-bonded fiber sheet, into a continuous strip and shaping it into a spiral with a predetermined inner diameter. The method is especially advantageous because it allows for the production of largesized round gaskets with only one seam, thereby significantly reducing material waste commonly known due to stamp-cutting loss. This method not only minimizes material waste but also enhances the structural integrity and reliability of the gasket by reducing potential failure points. The invention is particularly advantageous for producing large sizes of round gaskets with minimal waste, making it a highly efficient and reliable method for gasket production.

[0012] The efficiency of the method described in the invention is significantly enhanced by the streamlined process of forming gaskets. Instead of the conventional method of stamp-cutting, which can be labor-intensive and time-consuming, especially for large-diameter gaskets, this process utilizes a continuous strip formation technique. This approach drastically reduces the number of steps required to produce each gasket, as it eliminates the need for multiple cuts and adjustments that are typical in traditional methods.

[0013] In a preferred embodiment, the fiber sheet is provided by calendering which enhances the durability and reliability of the gasket product by maintaining material integrity and precision during the calendering and slitting processes. The use of specific temperature ranges, adjustable pitch, and constant pressure contributes to the overall efficiency and quality of the gasket production process.

[0014] DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention concerns a method for producing gaskets.

[0016] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0017] As used herein, the following terms have the following meanings:

[0018] The term "gasket" is synonym to "packing", and refers in the present invention to a mechanical seal that fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression.

[0019] The term "fiber sheet" as used herein refers to a flat, flexible material composed of interwoven or bonded fibers. The fibers may be natural, synthetic, or a composite of both, and the sheet can be formed through processes such as weaving, bonding using heat, pressure, or adhesives, and / or calendering. The fiber sheet can be a sheet consisting essentially of fibers or a sheet wherein the fibers are bonded by an elastomer binder, to obtain an elastomer-bonded fiber sheet.

[0020] The term "elastomer" is synonym to "rubber" and can refer to a partially or fully vulcanized polymer according to the terminology disclosed in ASTM D-1566.

[0021] The term "fiber mixture" refers in the present invention to a mixture that comprises fibers and optionally one or more other ingredients, such as a crude elastomer binder to obtain a fiber and elastomer mixture.

[0022] The term "crude elastomer", as used herein, refers to the raw, non-vulcanized or partially vulcanized polymer that can be present as binder in the fiber mixture before making an elastomer-bonded fiber sheet.

[0023] By the term "calendering" is meant in the present invention the process of pressing a fiber mixture between two or more calendering rollers to obtain a fiber sheet of desired thickness. The calendering rollers may each have a different calendering temperature. The term "calendering roller" in the present invention refers to a cylindrical tool. The roller can be heated or cooled to control the temperature during the calendering process.

[0024] The term "slitting" refers in the present invention to the process of cutting the fiber sheet into a continuous strip by pressing a blade against the roller while the roller is rotating. During slitting the blade moves parallel to the longitudinal axis of the roller, preferably with a predetermined pitch.

[0025] The term "continuous strip" is synonym to "gasket strip" is meant in the present invention a long, narrow piece of fiber sheet that has been slit from the original sheet.

[0026] The term "spiral with predetermined diameter" refers in the present invention to the process of forming the continuous strip into a spiral shape with a specific diameter, which is achieved by passing the strip through a set of rollers, preferably frustoconical rollers. By the term "ring-shaped strips" is meant in the present invention strips that have been cut from the spiraled continuous strip and have two ends that can be attached to form a gasket.

[0027] By the term "attaching" is meant in the present invention the process of joining the two ends of the ring-shaped strip to form a gasket. The attachment can be achieved by adhesive bonding or vulcanization welding.

[0028] The term "pitch" as used herein refers to the distance between successive cutting points or intervals at which the blade engages the fiber sheet, moving parallel to the axis of the roller. The "pitch" can be defined as the blade displacement per roller revolution.

[0029] "A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

[0030] "Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

[0031] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0032] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0033] The expression "% by weight", "weight percent", "%wt" or "wt%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation. Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members.

[0034] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, definitions for the terms used in the description are included to better appreciate the teaching of the present invention. The terms or definitions used herein are provided solely to aid in the understanding of the invention.

[0035] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0036] In a first aspect, the invention provides a method for producing gaskets, particularly the method is suitable for large-diameter gaskets. In an embodiment, the method is suitable for producing gaskets from fiber sheets, and comprises the steps of: providing a fiber sheet on a roller and slitting the fiber sheet into a continuous strip by pressing a blade against the roller.

[0037] One of the significant advantages of this method is the substantial reduction in material waste. Traditional stamp-cutting methods often result in considerable material loss, especially when stamping large-diameter rings. By contrast, the current process produces a long strip of material that can be shaped into large gaskets with minimal waste. This method results in gaskets having only one seam, further enhancing the integrity and performance of the final product. The efficiency of the method described in the invention is also significantly enhanced by the streamlined process of forming gaskets. Instead of the conventional method of stamp-cutting, which can be labor-intensive and time-consuming, especially for large-diameter gaskets, this process utilizes a continuous strip formation technique. This approach drastically reduces the number of steps required to produce each gasket, as it eliminates the need for multiple cuts and adjustments that are typical in traditional methods.

[0038] In a preferred embodiment, the fiber sheet is an elastomer-bonded fiber sheet. An elastomer-bonded fiber sheet is a composite material that combines fibrous elements with an elastomeric binder to create a flexible, durable sheet. The fibers are usually short, randomly oriented strands that can be made from various materials such as natural fibers, synthetic fibers, or mineral fibers. The choice of fiber depends on the required properties of the sheet, such as strength, flexibility, heat resistance, or chemical resistance.

[0039] In a preferred embodiment, the method for producing gaskets comprises the steps of: a. providing a fiber sheet, preferably an elastomer-bonded fiber sheet, on a roller; b. slitting the fiber sheet, preferably the elastomer-bonded fiber sheet, into a continuous strip by pressing a blade against the roller, c. shaping the continuous strip into a spiral with a predetermined inner diameter, d. cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a gasket.

[0040] The fiber sheet, preferably the elastomer-bonded fiber sheet, is present on a roller when it is slit into a continuous strip. In an embodiment the slitting is performed by a blade that moves parallel to the longitudinal axis of the roller with a predetermined pitch.

[0041] This parallel movement ensures that the cut is clean and precise and a continuous strip is obtained, reducing the likelihood of material wastage and enhancing the overall efficiency of the process. The parallel movement of the blade is preferably synchronized with the rotation of the roller to maintain a consistent pitch throughout the cutting process.

[0042] In an embodiment, steps (a) and (b) are performed at a different manufacturing site, and the product obtained therefrom is subsequently transported and supplied for use in step (c). Alternatively, the product resulting from steps (a) and (b) may be provided as a pre-manufactured continuous strip for use in step (c). Accordingly, steps (a) and (b) together can alternatively be defined as providing a continuous strip of a fiber sheet material, preferably an elastomer-bonded fiber sheet material, more preferably obtained by slitting a fiber sheet on a roller. In some embodiments, the continuous strip as referred to in step (b) may thus also be provided as a premanufactured product, for example obtained by purchasing or otherwise sourcing the continuous strip from an external manufacturer.

[0043] Preferably, the predetermined pitch is between 3 and 200 mm, more preferably 5 and 150 mm, even more preferably between 10 and 150 mm, even more preferably between 15 and 150 mm. The pitch will correspond with the width of the final gaskets, that is the difference between the outer diameter and the inner diameter of the final gaskets.

[0044] The predetermined pitch during the movement of the blade ensures that each gasket strip has the desired width. This configuration is designed to increase the consistency and efficiency of the production process. The pitch, which is defined as the blade displacement per roller revolution, is preferably set to achieve the precise width required for the gasket strips. This ensures that the gasket strips are uniform in width, which ensures the integrity and performance of the gaskets.

[0045] Preferably, the pitch can be adjusted within a specific range to accommodate different gasket widths. For instance, the pitch may be set between 1 mm and 150 mm. This allows for flexibility in the production process, enabling the manufacture of gasket strips of varying widths without compromising on quality.

[0046] In another embodiment, the pitch can be varied during slitting, to obtain more complex gaskets with varying width.

[0047] The blade can be made from steel, such as stainless steel or a similar material that is resistant to wear and corrosion. This ensures that the blade remains sharp and effective over extended periods of use, further enhancing the efficiency of the production process. The blade can also be made from other types of steel such as carbon steel, tool steel, high-speed steel, or other materials such as carbide, ceramics, etc.

[0048] The continuous strip produced by the slitting retains a degree of flexibility and deformability suitable for the subsequent shaping of the gasket strip into the desired inner diameter. The material properties of the continuous strip are preferably such that it can be easily manipulated to achieve the inner diameter required for the gasket. This ensures that the final gasket product is of high quality and meets the desired specifications.

[0049] Overall, the predetermined pitch and parallel movement of the blade, combined with the high-quality material of the blade and the flexibility of the gasket strip, contribute to a highly efficient and consistent production process. This results in gasket strips that are uniform in width, have minimal material wastage, and can be easily shaped into the desired inner diameter, thereby enhancing the overall performance and reliability of the gaskets.

[0050] In an embodiment, the fiber sheet has a thickness between 0.1 and 20 mm, preferably between 0.1 and 15 mm, more preferably between 0.1 and 5 mm, or even between 0.5 and 5 mm. The thickness of the fiber sheet will correspond with the thickness of the final gaskets.

[0051] The fiber sheet, preferably the elastomer-bonded fiber sheet, is present on a roller when it is slit into a continuous strip. In a preferred embodiment, the fiber sheet, preferably the elastomer-bonded fiber sheet, is provided by calendering a fiber mixture, preferably a fiber and elastomer mixture, between two or more calendering rollers. In this embodiment, the fiber sheet, preferably the elastomer-bonded fiber sheet, is made from a fiber mixture, preferably a fiber and elastomer mixture, by calendering, wherein the roller onto which the fiber sheet, preferably the elastomer- bonded fiber sheet, is slit, is the last calendering roll of the calendering process.

[0052] In this case a fiber mixture, preferably a fiber and elastomer mixture is fed to two or more calendering rollers to obtain an fiber sheet, preferably the elastomer- bonded fiber sheet, of a desired thickness. The calendering process begins with the preparation of a fiber mixture, preferably a fiber and elastomer mixture, which is brought to the desired thickness through a combination of turning and pressing on both hot and cold calendering rollers. In an embodiment, the desired thickness of fiber sheet is achieved through careful control of the roller settings. Once the proper thickness is attained, a blade is pressed against the roller and runs with a specific pitch parallel to the axis of the roller.

[0053] In an embodiment, the thickness of the fiber sheet can be adjusted within a specific range to accommodate different gasket thicknesses. For instance, the thickness may range from 0.5 mm to 20 mm, preferably between 1 mm and 5 mm, more preferably between 1 mm and 4 mm, most preferably between 1.5 mm and 3 mm.

[0054] The calendering process allows for precise control over the thickness of the fiber sheet, leading to consistent gasket quality. This process preferably involves the use of hot and cold rollers to turn and press the fiber / rubber compound mass to the desired thickness. In an embodiment, the calendering rollers each have a calendering temperature, and wherein at least one calendering roller has a lower calendering temperature.

[0055] In an embodiment, the temperature settings of the calendering rollers can be optimized to achieve the desired vulcanization state of the material. The temperature of the calendering rollers is preferably between 20°C to 200°C, preferably between 23°C and 180°C.

[0056] The temperature of the hottest calendering rollers is preferably between 100°C to 200°C, preferably between 120°C and 180°C, more preferably between 140°C and 180°C. The colder rollers preferably have a temperature between 10°C to 50°C, preferably between 15°C and 40°C, more preferably between 20°C and 30°C, most preferably around 25°C. The relatively low calendering temperatures ensures that the sheet and slit strip can still be shaped to a desired diameter.

[0057] The non or partially vulcanized fiber and elastomer mixture will attach itself to the hottest of the two rolls. When the proper thickness is reached on the last calendering rollers, a blade is preferably pressed against the hotter roll to slit the sheet. This method ensures that the material is cut precisely at the desired thickness, maintaining the consistency and quality of the gasket strip.

[0058] The elastomer-bonded fiber sheet can be vulcanized, partially vulcanized, or nonvulcanized prior to slitting. Preferably, the sheet is at least partially vulcanized prior to slitting to enhance its mechanical strength and durability, making it suitable for applications where robust performance is essential. More preferably, the sheet is partially vulcanized, which allows for further processing steps such as shaping and forming before final vulcanization. This intermediate state can provide a balance between strength and malleability, facilitating easier handling and manipulation during manufacturing.

[0059] After slitting in step b, the continuous strip has sufficient flexibility and deformability, allowing it to be shaped into a spiral with a predetermined inner diameter. In an embodiment, the shaping is performed by passing the continuous strip through a set of rollers, the set of rollers preferably being a pair of rollers.

[0060] The continuous strip is preferably shaped into a spiral with an inner diameter that almost matches the desired gasket diameter. More preferably, the strip can be rolled into an inner diameter that matches the desired gasket inner diameter exactly.

[0061] In a further embodiment, the set of rollers are frustoconical rollers. The use of frustoconical rollers ensures that the strip has the desired inner diameter for any required gasket diameter, thereby enhancing the precision and efficiency of the manufacturing process. Using frustoconically shaped rollers can help minimize effects related to uneven tension or distribution of forces in the material during the process, causing it to lose its flatness, by distributing the forces more evenly across the material, thus preventing unwanted deformation.

[0062] In an embodiment, the continuous strip is shaped into a spiral with a predetermined inner diameter of at least 3 mm, preferably at least 10 mm. The predetermined inner diameter is to be understood as the inner diameter of the spiral. The process is especially advantageous for large diameter gaskets, such as larger than 3 mm.

[0063] In another or further embodiment, the continuous strip is shaped into a spiral with a predetermined inner diameter between 3 and 3000 mm, preferably between 3 and 2500 mm, preferably between 3 and 2000 mm.

[0064] In another preferred embodiment, the inner diameter achieved by the frustoconical rollers can be varied within a range, allowing for the production of gaskets with different diameters. This ensures that the process can cater to a wide variety of gasket sizes, making it highly versatile. Additionally, the rollers may be heated to a specific temperature to facilitate the shaping process. The operating temperature of the rollers is preferably between 25°C and 200°C, more preferably between 25°C and 175°C, more preferably between 25°C and 150°C, more preferably between 25°C and 140°C. This temperature range ensures optimal shaping conditions without compromising the integrity of the elastomeric bonded fiberboard material.

[0065] In an embodiment, the process may optionally include a cooling phase after the shaping to stabilize the material. This cooling phase is preferably conducted at temperatures between 0°C and 50°C, more preferably between 10°C and 40°C, more preferably between 15°C and 35°C, more preferably between 20°C and 30°C, and most preferably around 25°C. The cooling phase helps in maintaining the desired shape and dimensions of the gasket, ensuring that it retains its form during subsequent handling and installation.

[0066] The spiraled strip can subsequently be cut, thereby obtaining ring-shaped strips with two ends. The two ends of the open ring-shaped strips can then be attached to form a gasket.

[0067] The spiraled strip is preferably cut into multiple ring-shaped strips with two open ends. In a preferred embodiment, the process involves sealing the ring-shaped strips to form gaskets by attaching said two ends. This sealing process preferably ensures that only one seam is present in the final gasket, which is highly advantageous for maintaining the structural integrity and performance of the gasket. More preferably, the seam is created through local vulcanization welding or gluing, which provides a strong and durable bond. This method is particularly beneficial as it minimizes the potential for leaks or weaknesses that could arise from multiple seams. The seal can also be created through all kinds of sealing processes, such as vulcanization, glue / adhesive bonding, thermal welding, ultrasonic welding friction welding, laser welding, mechanical fastening, clamping, riveting, bolting or screwing, pressure sealing, heat sealing, crimping, cold welding, compression fitting, solvent welding, induction sealing, and sintering.

[0068] In an embodiment, the fiber sheet, preferably the elastomer-bonded fiber sheet, comprises one or more fibers chosen from synthetic fibers, natural fibers or mineral fibers. In a further or another embodiment, the fiber sheet, preferably the elastomer- bonded fiber sheet, comprises one or more fibers chosen from aramid fiber, polyester fiber, polypropylene fiber, acrylic fiber, carbon fiber, cellulose, glass fiber, ceramic fiber, basalt fiber or mica fiber, preferably the elastomer-bonded fiber sheet comprises aramid fiber or carbon fiber.

[0069] In an embodiment, the elastomer-bonded fiber sheet comprises one or more elastomers chosen from : neoprene rubber, chlorosulfonated polyethylene rubber (CSM), chloroprene rubber (CR), ethylene propylene diene monomer rubber (EPDM), fluorinated rubber, such as FKM or FPM, silicone rubber, styrene butadiene rubber (SBR) or nitrile butadiene rubber (NBR), preferably the one or more elastomer, preferably one elastomer, is chosen from nitrile butadiene rubber (NBR) or ethylene propylene diene monomer rubber (EPDM).

[0070] In a specific embodiment, the elastomer-bonded fiber sheet comprises an elastomer chosen from NBR, EPDM, or a combination thereof, and one or more fibers chosen from aramid fiber, carbon fiber, or a combination thereof.

[0071] In a specific embodiment, the elastomer-bonded fiber sheet is an NBR-bonded or EPDM-bonded aramid or carbon fiber sheet.

[0072] It is to be understood that elastomer-bonded fiber sheets having a certain composition are made from fiber and elastomer mixtures having that same composition.

[0073] The fiber content in fiber sheet can range from 5 to 40% by weight, more preferably from 5 to 25% by weight, even more preferably from 5 to 20% by weight, even more preferably from 10 to 15% by weight.

[0074] In an embodiment, the method allows for the incorporation of additives into the elastomeric matrix to further customize the properties of the gasket. These additives may include fillers, plasticizers, or stabilizers, each serving to enhance specific aspects of the gasket's performance. For instance, fillers such as carbon black or silica can be added to improve the mechanical strength and wear resistance of the gasket.

[0075] In a specific embodiment, the method comprises the steps of: a. calendering a fiber and elastomer mixture, between two or more calendering rollers to obtain an elastomer-bonded fiber sheet, wherein the fiber and elastomer mixture comprises an elastomer binder and one or more fibers, b. slitting the elastomer-bonded fiber sheet into a continuous strip by pressing a blade against the last calendering roller, c. shaping the continuous strip into a spiral with a predetermined inner diameter, d. cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a elastomer-bonded fiber gasket.

[0076] In a further embodiment, the method preferably involves the use of rollers, preferably frustoconical rollers, to shape the elastomer-bonded fiber sheet into a desired inner diameter, which is particularly beneficial when producing large- diameter gaskets.

[0077] This method of producing gaskets is especially advantageous as it significantly reduces material waste, in the form of stamp-cutting loss. The method, which enhances the efficiency and cost-effectiveness of the production process, results in gaskets with only one seam. Additionally, the ability to adjust the pitch and the angle of the frustoconical rolls provides flexibility in producing gaskets of various sizes and dimensions, making the method highly adaptable to different requirements.

[0078] The single-seam design of the gasket is an advantageous feature that enhances the overall performance and reliability of the seal. Seals with fewer seams are generally stronger because seams are potential weak points where failures can occur due to differential stresses that accumulate at these junctions. By minimizing the number of seams, the structural integrity of the seal is improved, leading to better durability and a lower likelihood of failure under pressure or stress. This is particularly important in applications involving hazardous or volatile substances, where a leak could have serious safety implications. A single-seam design simplifies the pathway and reduces the chances of leakage, making the seal more reliable.

[0079] In an embodiment, the spiraled continuous strip can undergo a vulcanization before cutting the strip. In another embodiment, the cut ring-shaped strips can undergo a vulcanization before attaching the ends. In yet another embodiment, the gaskets can undergo a vulcanization after attaching the ends.

[0080] In a further preferred embodiment, the vulcanization process is conducted at temperatures ranging from 100°C to 500°C. More preferably, the temperature is between 150°C and 450°C, more preferably between 150°C and 400°C, more preferably between 150°C and 350°C, more preferably between 150°C and 300°C, and most preferably between 150°C and 250°C.

[0081] Additionally, in another preferred embodiment, the duration of the vulcanization process may vary depending on the specific requirements of the material and the application. Preferably, the vulcanization time ranges from 1 minutes to 60 minutes. More preferably, the time is between 5 minutes and 60 minutes, more preferably between 10 minutes and 50 minutes, more preferably between 15 minutes and 40 minutes, more preferably between 20 minutes and 30 minutes.

[0082] In a second aspect the invention relates to a gasket comprising an elastomer. The gasket is formed from a ring-shaped strip with two ends, wherein said two ends are attached to form a gasket comprising only one seam. The term "seam" as used herein refers to the joint or line where two ends of the ring-shaped strip are connected to form the gasket.

[0083] The gasket is preferably produced by a method as described above.

[0084] In a preferred embodiment, the gasket is an elastomer-bonded fiber gasket, preferably such as described above. In one embodiment the gasket is an NBR- bonded or EPDM-bonded aramid or carbon fiber gasket.

[0085] In an embodiment, the gasket has an inner diameter between 3 and 3000 mm, preferably between 10 and 3000 mm, more preferably between 10 and 2500 mm, or even between 10 and 2000 mm.

[0086] In another or further embodiment, the gasket has a thickness between 0.1 and 20 mm, preferably between 0.1 and 15 mm, more preferably between 0.1 and 5 mm, or even between 0.5 and 5 mm.

[0087] In another or further embodiment, the gasket has a width between 3 and 150 mm, more preferably 5 and 150 mm, even more preferably between 10 and 150 mm, even more preferably between 15 and 150 mm.

[0088] The invention is further described by the following non-limiting examples which further illustrate the invention, and are not intended to, nor should they be interpreted to, limit the scope of the invention. EXAMPLES AND DESCRIPTION OF FIGURES

[0089] Example 1

[0090] To better exemplify reference is made to figures 1 and 2. Figure 1 shows a production method for gaskets according to an embodiment of the current invention. Figure 2 shows a gasket according to an embodiment of the current invention.

[0091] Herein, an elastomer-bonded fiber sheet (1) is provided on a roller (2a) and subsequently slit with a blade (3) moving along the axis (12) of the roller (2a) with a predetermined pitch (6) to obtain a continuous elastomer strip (4). The direction of the blade (3) is indicated with an arrow. With "continuous strip" it is meant that one strip, without discontinuities, is produced from the elastomer-bonded fiber sheet (1).

[0092] The pitch (6), which determines the width (A) of the desired gasket (7), is preferably adjustable to accommodate various gasket dimensions. This slitting process allows for the continuous production of gasket with minimal waste.

[0093] The continuous strip (4) produced from the slitting process retains sufficient flexibility and deformability. This flexibility is advantageous as it enables the strip (4) to be pressed by frustoconical rollers (5), creating a spiraled strip (8). The strip (4) can be spiraled into a spiral with an inner diameter (9) that nearly matches the desired gasket diameter (B). The ability to roll the gasket strip into a near-final shape significantly reduces material waste and enhances production efficiency.

[0094] Additionally, the spiraled strip (8) is preferably cut to obtain ring-shaped strips with two open ends (not shown). The spiraled strip (8) can, for example, be cut at a cutting line (14), which is shown as a dotted line in figure 1. Afterwards the beginning of the spiral (15) can be attached to the resulting cut end at the dotted line to form a first gasket.

[0095] The ends of the strip are joined together by local vulcanization welding or gluing to form an endless gasket ring. The obtained gasket (7) can be characterized by a width (A), an inner diameter (B), and outer diameter (C) and a thickness (D). The gasket (7) has one seam (13), said seam being the joint where said two ends of the ringshaped strip are connected to form the gasket. The method may involve the use of different elastomeric materials, which can be selected based on the specific requirements of the gasket application, such as temperature resistance, chemical compatibility, and mechanical properties.

[0096] Example 2

[0097] To better exemplify reference is made to figures 1, 2 and 3. Figure 1 shows a production method for gaskets according to an embodiment of the current invention. Figure 2 shows a gasket according to an embodiment of the current invention. Figure 3 shows a calendering process according to an embodiment of the current invention.

[0098] Example 2 is the same as example 1, but the method involves the preparation of an elastomer-bonded fiber sheet (1) from a fiber and elastomer mixture (10) through calendering (11), wherein the elastomer-bonded fiber sheet (1) is brought to the desired thickness through a series of turning and pressing actions on hot and cold rollers (2a-2d). During calendering (11) the elastomer-bonded fiber sheet (1) is partially vulcanized material is processed until it reaches its final vulcanized state on a hot roller (2a).

[0099] Once the desired thickness is achieved, a blade (3) moving along the axis (12) of the roller (2) with a predetermined pitch (6) to obtain a continuous elastomer strip (4). The direction of the blade (3) is indicated with an arrow. With "continuous strip" it is meant that one strip, without discontinuities, is produced from the elastomer- bonded fiber sheet (1).

[0100] The pitch (6), which determines the width (A) of the desired gasket (7), is preferably adjustable to accommodate various gasket dimensions. This slitting process allows for the continuous production of gasket with minimal waste.

[0101] The continuous strip (4) produced from the slitting process retains sufficient flexibility and deformability. This flexibility is advantageous as it enables the strip (4) to be pressed by frustoconical rollers (5), creating a spiraled strip (8). The strip (4) can be spiraled into a spiral with an inner diameter (9) that nearly matches the desired gasket diameter (B). The ability to roll the gasket strip into a near-final shape significantly reduces material waste and enhances production efficiency.

[0102] Additionally, the spiraled strip (8) is preferably cut to obtain ring-shaped strips with two open ends (not shown). The spiraled strip (8) can, for example, be cut at a cutting line (14), which is shown as a dotted line in figure 1. Afterwards the beginning of the spiral (15) can be attached to the resulting cut end at the dotted line to form a first gasket.

[0103] The ends of the strip are joined together by local vulcanization welding or gluing to form an endless gasket ring. The obtained gasket (7) can be characterized by a width (A), an inner diameter (B), and outer diameter (C) and a thickness (D). The gasket (7) has one seam (13), said seam being the joint where said two ends of the ringshaped strip are connected to form the gasket.

[0104] The method may involve the use of different elastomeric materials, which can be selected based on the specific requirements of the gasket application, such as temperature resistance, chemical compatibility, and mechanical properties.

[0105] The present invention is in no way limited to the embodiments described in the examples and / or shown in the figures. On the contrary, methods according to the present invention may be realized in many different ways without departing from the scope of the invention.

[0106] The invention may thus be described according to the following embodiments:

[0107] 1. A method for producing gaskets comprising the steps of: a. providing an elastomer-bonded fiber sheet on a roller, b. slitting the elastomer-bonded fiber sheet into a continuous strip by pressing a blade against the roller, c. shaping the continuous strip into a spiral with a predetermined inner diameter, d. cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a gasket.

[0108] 2. Method according to embodiment 1, wherein, during slitting, the blade moves parallel to the longitudinal axis of the roller with a predetermined pitch.

[0109] 3. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet is partially or fully vulcanized.

[0110] 4. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet is provided by calendering a fiber and elastomer mixture between two or more calendering rollers.

[0111] 5. Method according to embodiment 4, wherein the calendering rollers have each have a calendering temperature, and wherein at least one calendering roller has a lower calendering temperature. 6. Method according to any of the previous embodiments, wherein the continuous strip is passed through a set of rollers during in step c.

[0112] 7. Method according to embodiment 6, wherein the set of rollers are frustoconical rollers.

[0113] 8. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises an elastomer chosen from : neoprene rubber, chlorosulfonated polyethylene rubber (CSM), chloroprene rubber (CR), ethylene propylene diene monomer rubber (EPDM), fluorinated rubber, such as FKM or FPM, silicone rubber, styrene butadiene rubber (SBR) or nitrile butadiene rubber (NBR).

[0114] 9. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises one or more fibers chosen from synthetic fibers, natural fibers or mineral fibers.

[0115] 10. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises one or more fibers chosen from aramid fiber, polyester fiber, polypropylene fiber, acrylic fiber, carbon fiber, cellulose, glass fiber, ceramic fiber, basalt fiber or mica fiber, preferably aramid fiber or carbon fiber.

[0116] 11. Method according to any of embodiments any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises an elastomer chosen from NBR, EPDM, or a combination thereof, and one or more fibers chosen from aramid fiber, carbon fiber, or a combination thereof.

[0117] 12. Method according to any of the previous embodiments, wherein the two ends of the strip are attached by adhesive or vulcanization.

[0118] 13. Method according to any of the previous embodiments, comprising the steps of: a. calendering a fiber and elastomer mixture between two or more calendering rollers to obtain an elastomer-bonded fiber sheet, wherein the fiber and elastomer mixture comprises an elastomer binder and one or more fibers, b. slitting the elastomer-bonded fiber sheet, into a continuous strip by pressing a blade against the last calendering roller, c. shaping the continuous strip into a spiral with a predetermined inner diameter, d. cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a elastomer-bonded fiber gasket. A gasket comprising an elastomer, wherein the gasket is formed from a ringshaped strip with two ends, wherein the two ends are joined to form a single seam at their connection. Gasket according to embodiment 14, the gasket being an elastomer-bonded fiber gasket, preferably an NBR-bonded or EPDM-bonded aramid or carbon fiber gasket. Gasket according to embodiment 14 or 15, the gasket being produced by a method according to any of embodiments 1-13.

Claims

CLAIMS1. A method for producing gaskets comprising the steps of: a. providing an elastomer-bonded fiber sheet on a roller, b. slitting the elastomer-bonded fiber sheet into a continuous strip by pressing a blade against the roller, c. shaping the continuous strip into a spiral with a predetermined inner diameter, d. cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a gasket.

2. Method according to embodiment 1, wherein, during slitting, the blade moves parallel to the longitudinal axis of the roller with a predetermined pitch.

3. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet is partially or fully vulcanized.

4. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet is provided by calendering a fiber and elastomer mixture between two or more calendering rollers.

5. Method according to embodiment 4, wherein the calendering rollers have each have a calendering temperature, and wherein at least one calendering roller has a lower calendering temperature.

6. Method according to any of the previous embodiments, wherein the continuous strip is passed through a set of rollers during in step c.

7. Method according to embodiment 6, wherein the set of rollers are frustoconical rollers.

8. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises an elastomer chosen from : neoprene rubber, chlorosulfonated polyethylene rubber (CSM), chloroprene rubber (CR), ethylene propylene diene monomer rubber (EPDM), fluorinated rubber, such as FKM or FPM, silicone rubber, styrene butadiene rubber (SBR) or nitrile butadiene rubber (NBR).

9. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises one or more fibers chosen from synthetic fibers, natural fibers or mineral fibers.

10. Method according to any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises one or more fibers chosen from aramid fiber, polyester fiber, polypropylene fiber, acrylic fiber, carbon fiber, cellulose, glass fiber, ceramic fiber, basalt fiber or mica fiber, preferably aramid fiber or carbon fiber.

11. Method according to any of embodiments any of the previous embodiments, wherein the elastomer-bonded fiber sheet comprises an elastomer chosen from NBR, EPDM, or a combination thereof, and one or more fibers chosen from aramid fiber, carbon fiber, or a combination thereof.

12. Method according to any of the previous embodiments, wherein the two ends of the strip are attached by adhesive or vulcanization.

13. Method according to any of the previous embodiments, comprising the steps of: a. calendering a fiber and elastomer mixture between two or more calendering rollers to obtain an elastomer-bonded fiber sheet, wherein the fiber and elastomer mixture comprises an elastomer binder and one or more fibers, b. slitting the elastomer-bonded fiber sheet, into a continuous strip by pressing a blade against the last calendering roller, c. shaping the continuous strip into a spiral with a predetermined inner diameter, d. cutting the spiraled strip thereby obtaining ring-shaped strips with two ends, and attaching said two ends to form a elastomer-bonded fiber gasket.

14. A gasket comprising an elastomer, wherein the gasket is formed from a ringshaped strip with two ends, wherein the two ends are joined to form a single seam at their connection.

15. Gasket according to embodiment 14, the gasket being an elastomer-bonded fiber gasket, preferably an NBR-bonded or EPDM-bonded aramid or carbon fiber gasket.

16. Gasket according to embodiment 14 or 15, the gasket being produced by a method according to any of embodiments 1-13.

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