Patent Application
20180319046
The present disclosure relates in general to wind turbines, and more particularly to systems and methods for manufacturing wind turbine rotor blade components using dynamic mold heating for curing the composite material thereof.
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from the wind using known airfoil principles. The rotor blades transform the kinetic energy into a form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Conventional wind turbine rotor blades include a body shell with various structural components configured therein to provide the desired stiffness and/or strength for supporting the loads imposed on the rotor blade during operation. For example, the structural components often include opposing spar caps configured on inner surfaces of the upper and lower shell members and a shear web mounted between the opposing spar caps.
To increase the structural strength of the rotor blade components, the body shell is typically formed in halves or other portions that extend along the entire length of the finished blade. Specialized molding and curing equipment is typically used to accommodate such blade components, which continue to increase in length as more power is desired from larger wind turbines. More specifically, large composite rotor blade components are generally manufactured using layup techniques that include arranging one or more layers of plies of reinforcing fiber material in large molds either by hand or by automated equipment. Once the plies have been arranged in the mold, resin is supplied to the mold using a technique such as resin transfer molding (RTM), vacuum-assisted resin transfer molding (VARTM), or any other suitable infusion method. Alternatively, the plies may be pre-impregnated with a resin material, i.e. pre-preg.
In addition, the plies are generally subjected to a vacuum-assisted and temperature-controlled consolidation and curing process. For example, after the vacuum infusion of the resin is complete, the set point temperature for the mold is raised to a cure temperature. After the resin has finished an exothermic reaction, the set point temperature may be adjusted to a new final cure temperature, after which the component is left to set for a predetermined time period in order for component to completely cure.
Some current wind blade manufacturing techniques use molds that have a plurality of heating zones embedded with heating coils, the number of which varies depending on the type of mold. A mold heat control system is used to set the mold heating profile and adjust energy supplied to the heating zones based on the temperature measured at each heating zone. Each of the heating zones, however, is set to follow the same temperature profile part after part regardless of the local difference in the laminate schedules between zones, the variations in cure profile characteristics within each heating zone, and/or the impact of environmental conditions. Because of the large variation in laminate structure in large wind turbine composite parts, the rate of cure will vary greatly between zones. As such, conventional manufacturing methods for certain parameters result in some regions of the component obtaining a sufficient degree of cure (DOC) for demolding, while other regions are under cured. Therefore, a safety margin is built into the temperature profiles to ensure that the entire component is cured, which not only induces high processing cost and longer cycles, but also regional over cure.
Thus, there is a need for a system and method for manufacturing wind turbine blade components that addresses the aforementioned issues. More specifically, there is a need for a system and method for manufacturing wind turbine rotor blade components that uses dynamic mold heating control for curing the components that takes into account the variations in the cure rate between the different zones of the mold.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one aspect, the present disclosure is directed to a method for manufacturing a rotor blade component of a wind turbine. The method includes providing a mold body that is divided into a plurality of mold zones. Each of the mold zones has at least one sensor associated therewith for sensing a temperature or degree-of-cure thereof. The method also includes providing a composite material schedule for each of the mold zones. Further, the method includes placing composite material onto the mold body according to the composite material schedule. Moreover, the method includes supplying a resin material to each mold zone of the mold body. In addition, the method includes implementing a cure cycle for the rotor blade component. More specifically, the cure cycle includes supplying heat to each of the mold zones, continuously receiving, via a controller, signals from the sensors from one or more of the mold zones, and dynamically controlling the supplied heat to each mold zone based on the received signals and the composite material schedule of each mold zone until the cure cycle is complete.
In one embodiment, the step of dynamically controlling the supplied heat to each mold zone based on the received signals and the composite material schedule of each mold zone until the cure cycle is complete may include generating a unique temperature profile for each of the mold zones based on the composite material schedule and controlling the supplied heat to each mold zone based on the unique temperature profile provided thereto until the cure cycle is complete.
In another embodiment, the method may further include continuously optimizing the cure cycle during implementation via machine learning. In such embodiments, the step of continuously optimizing the cure cycle during implementation via machine learning may include determining initial operating parameters for each of the mold zones, optimizing the initial operating parameters via computer simulation, and sending the optimized initial operating parameters to the controller to utilize in the cure cycle. More specifically, in certain embodiments, the initial operating parameters may include an initial set point, a ramp rate, a cure temperature, a final cure time, or another other parameter relating to the curing process.
In further embodiments, the method may include comparing the cure cycle against the computer simulation and optimizing the cure cycle based on differences between the cure cycle and the computer simulation. For example, in one embodiment, the method may include adjusting an initial set point, an initial ramp rate, an initial cure temperature, and/or a final cure time for each of the mold zones.
In another embodiment, the method may include optimizing the cure cycle based on one or more historical cure cycles. In additional embodiments, the method may include generating operating data during the cure cycle, storing the operating data, and utilizing the stored operating data to optimize subsequent cure cycles.
In several embodiments, the step of continuously receiving, via the controller, signals from the sensors may include receiving at least one of temperature signals or degree-of-cure signals from one or more of the mold zones or a group of the mold zones.
In particular embodiments, the step of dynamically controlling the supplied heat to each mold zone based on the received signals and the composite material schedule of each mold zone until the cure cycle is complete may include maintaining a uniform temperature profile along a length of the mold body.
In another aspect, the present disclosure is directed to a method for curing a rotor blade component of a wind turbine formed using a mold body that is divided into a plurality of mold zones. In addition, a composite material schedule is provided for each of the mold zones. Further, each of the mold zones has at least one sensor associated therewith for sensing a temperature or degree-of-cure thereof. Thus, the method includes supplying heat to each of the mold zones containing a composite material placed according to the composite material schedule. Moreover, the method includes continuously receiving, via a controller, signals from the sensors from each mold zone. Thus, the method includes dynamically controlling the supplied heat to each mold zone based on the received signals and the composite material schedule of each mold zone until the cure cycle is complete. It should be understood that the method may further include any of the additional steps, features, and/or embodiments as described herein.
In yet another aspect, the present disclosure is directed to a mold assembly for manufacturing a rotor blade component of a wind turbine. The mold assembly includes a mold body defining a surface configured to receive composite material for forming the rotor blade component according to a composite material schedule. The mold body is divided into a plurality of mold zones, each of which includes at least one heating/cooling element configured to heat or cool the rotor blade component at that mold zone. The mold assembly also includes a plurality of sensors configured with the mold body, with at least one of the plurality of sensors configured with each of the mold zones. In addition, the mold assembly includes a controller operatively coupled to the plurality of sensors. As such, the controller is configured to perform one or more operations, including but not limited to, receiving a temperature and/or degree-of-cure signal from each of the plurality of sensors from each mold zone, and dynamically controlling the heating/cooling elements of each mold zone based on the received signals and the composite material schedule of each mold zone until the cure cycle is complete. It should be understood that the method may further include any of the additional steps, features, and/or embodiments as described herein.
In one embodiment, the mold zones may be thermally isolated from one another. In another embodiment, the heating/cooling elements may include coils embedded in each mold zone, heated fluids, cooling fluids, or a temperature-controlled blanket. It should be understood that the mold assembly may further include any of the additional features and/or embodiments as described herein.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Generally, the present disclosure is directed to a method and mold assembly for manufacturing a rotor blade component of a wind turbine that eliminates issues associated with all mold zones of the mold being heated according to a fixed temperature profile. Rather, the method and mold assembly of the present disclosure involves constantly optimizing the temperature profiles of each mold zone via machine learning. For example, to establish optimal initial operating parameters for each mold zone, the cure cycle is first optimized for each mold zone using computer simulation based on the laminate schedule, e.g. composite molding simulation software such as the PAM/RTM software. More specifically, the method may include developing one or more algorithms that run the computer simulation repetitively and adjusting the temperatures profile for each mold zones (i.e. within limits) to achieve the shortest overall cure cycle. For example, the method may include adjusting the initial set point, ramp rate, initial cure temperature, final cure, etc. for each mold zone.
After the initial operating parameters are determined, such parameters, along with the expected degree-of-cure (DOC) and the temperature profiles are provided to the mold curing controller. The controller then runs the cure cycle, but rather than running the cycle against a fixed temperature profile, the controller monitors the temperature of each mold zone (or a group of mold zones) and the performance of the cure against the simulation results. For example, in one embodiment, the rate of cure during the initial ramp up (where the laminate may be thick enough to produce a exothermic reaction which causes the temperature to run above the programmed temperature profile or thin enough (or insulated by core or prefabricated parts) where the controller cannot deliver enough energy to achieve the temperature profile) may be monitored. Though the initial computer simulation is configured to predict such variations, the controller is configured to determine any deviations between the simulation and actual operating parameters and attempt, through controlling each zone, to correct or improve the performance relative to the simulation. Such corrections may be achieved via the sensors associated with each mold zone as well as additional side thermocouples, imbedded thermocouples, and/or dielectric devices which can directly measure the DOC and/or the temperature of the mold.
The method may also include zone-by-zone optimization of subsequent cure cycles by collecting performance data and results of multiple cures to further optimize and improve the system performance. For example, additional variables may be considered and optimized such as ambient temperature, humidity, resin bulk storage temperatures, the time under vacuum, the vacuum level, resin batch variations, resin manufacturer variations, and/or any other operation variables. Thus, the controller of the present disclosure is configured to learn the impact of all of the possible variables, and take action to optimize the individual cure cycles.
Referring now to the drawings,
Referring now to
In several embodiments, the body shell 21 may be formed from a plurality of rotor blade segments 38. For example, as shown in
Additionally, the rotor blade segments 38 may generally be formed from any suitable material. For instance, in one embodiment, the body shell 21 may be formed entirely from a laminate composite material, such as a carbon fiber reinforced laminate composite or a glass fiber reinforced laminate composite. Alternatively, one or more portions of the body shell 21 may be configured as a layered construction and may include a core material, formed from a lightweight material such as wood (e.g., balsa), foam (e.g., extruded polystyrene foam) or a combination of such materials, disposed between layers of laminate composite material. In additional embodiments, the body shell 21 may be formed of any suitable composite material, including thermoplastic and/or thermoset materials.
Referring particularly to
The spar caps 20, 22 and the one or more shear webs 24 may be formed from any suitable material, including but not limited to laminate composite materials; such as a carbon fiber reinforced laminate composite or a glass fiber reinforced laminate composite. In addition, the spar caps 20, 22 may be formed via one or more pultrusions or pultruded members. As used herein, the terms “pultrusions,” “pultruded members” or similar generally encompass reinforced materials (e.g. fibers or woven or braided strands) that are impregnated with a resin and pulled through a heated stationary die such that the resin cures or undergoes polymerization. As such, the process of manufacturing pultruded composites is typically characterized by a continuous process of composite materials that produces composite parts having a constant cross-section.
Referring now to
Thus, as shown at 104, the method 100 also includes providing a composite material schedule 46 for each of the mold zones 42. As described herein, a composite material schedule generally refers to an amount of composite material that is required in each zone 42. For example, as shown in the illustrated embodiment of
Thus, as shown at 106, the method 100 includes placing composite material onto the mold body 41 according to the composite material schedule 50. For example, as shown in
Referring back to
Referring still to
As used herein, the term “processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits. The processor(s) 46 is also configured to compute advanced control algorithms and communicate to a variety of Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Additionally, the memory device(s) 47 may generally comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) 47 may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s) 46, configure the controller 45 to perform the various functions as described herein.
Referring back to
Referring still to
In another embodiment, the method 100 may further include continuously optimizing the cure cycle during implementation thereof, e.g. via machine learning. In such embodiments, the controller 45 is configured to determine initial operating parameters for each of the mold zones 42. To establish the initial operating parameters for each zone 42, the cure cycle may be optimized for each zone 42 using computer simulation software. Optimization in this step includes developing algorithms which run the simulation repetitively and adjusts the cure profile for each mold zone 42 (within limits) to achieve the shortest overall cure cycle. In certain embodiments, the initial operating parameters may include an initial set point, a ramp rate, a cure temperature, a final cure time, or another other parameter relating to the curing process.
Thus, once the initial operating parameters are determined, the controller 45 is configured to utilize parameters in the cure cycle. After a cure cycle is implemented, in certain embodiments, the method 100 may also include comparing the actual cure cycle against the computer simulation of the cure cycle and optimizing the actual cure cycle based on differences between the two. For example, in one embodiment, the method 100 may include adjusting various set points, ramp rates, cure temperatures, and/or the final cure time for each of the mold zones 42. In another embodiment, the controller 45 may be programmed to perform a simulation of the balance of the cure cycle, while the cure cycle is underway to predict and guide the remainder of cycle. As such, the controller 45 can use the results for further optimization. In another embodiment, the method 100 may include optimizing the cure cycle based on one or more historical cure cycles. In particular embodiments, the method 100 may include generating operating data during the cure cycle, storing the operating data, e.g. in the memory device(s) 47, and utilizing the stored operating data to optimize subsequent cure cycles.
Referring now to
Thus, the methods of the present disclosure utilize machine learning algorithms in conjunctions with cure kinetic simulation and sensor feedback to enable each mold zone 42 to have an individual temperature or heating profile that can be optimized either before starting a cure cycle, concurrently while a cure cycle is being implemented, or via multiple cure history. In other words, as mentioned, optimization can be done initially by running simulation of the cure cycle for each zone 42 (e.g. via PAM/RTM software offered by ESI Group) with allowable mold and exothermic temperatures. As such, the derived DOC and temperature profiles can be used to gage actual cure performance during a cure cycle and concurrently adjust the mold parameters. Further, information gained during each cure cycle can be used better understand and further optimize the cure cycles.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
