Patent Publication Number: US-2021178659-A1

Title: Grooved die for manufacturing unidirectional tape

Description:
FIELD OF THE DISCLOSURE 
     This disclosure relates to manufacturing plastics, in particular, to methods and equipment for manufacturing thermoplastics. 
     BACKGROUND OF THE DISCLOSURE 
     Thermoplastic components can be made with continuous reinforced fibers, such as carbon fiber, glass fiber, or aramid fiber. Thermoplastic components exhibit high stiffness-to-weight ratios and other mechanical properties that make them desirable in multiple applications. Manufacturing thermoplastic components can be costly and time-consuming. Methods and systems for manufacturing thermoplastic components are sought. 
     SUMMARY 
     Implementations of the present disclosure include a method of manufacturing thermoplastic components. The method includes receiving, by a movable die with an internal grooved surface that has a plurality of longitudinal grooves, spread dry fiber tows. The method also includes receiving, by the movable die and from a polymer extruder fluidically coupled to the movable die, molten polymer. The method also includes wetting, by the movable die, the spread fiber tows with the molten polymer. The method also includes moving, by the movable die, the wet fiber tows along the plurality of longitudinal grooves in a direction parallel to a length of the longitudinal grooves. The longitudinal grooves help prevent the wet fiber tows from mingling as the wet fiber tows move along the longitudinal grooves to exit the movable die. The method also includes depositing, by the movable die, a layer of the wet fiber tows on a printing surface. The movable die moves along the printing surface to form a thermoplastic component of one or more layers of fiber tows on the printing surface. 
     In some implementations, the movable die has an internal channel fluidically coupled to the polymer extruder. The internal channel flows the molten polymer from the polymer extruder to the internal grooved surface of the movable die. Wetting the spread fiber tows includes wetting the spread fiber tows at the internal grooved surface as the wet fiber tows move along the internal grooved surface. In some implementations, the internal channel is disposed upstream of the internal grooved surface and extends parallel to a length of the longitudinal grooves. In such implementations, wetting the spread fiber tows includes flowing the molten polymer into the internal grooved surface to flow along the longitudinal grooves. In some implementations, the internal channel extends from a fluid inlet of the movable die to the internal grooved surface, with the movable die having a fiber inlet disposed downstream of the fluid inlet. In such implementations, receiving the spread dry fiber tows includes receiving the spread dry fiber tows at such fiber inlet of the movable die. In such implementations, the internal channel is disposed at the internal grooved surface and extends laterally across the internal grooved surface, and wetting the spread fiber tows includes flowing the molten polymer across the longitudinal grooves. In such implementations, the internal channel extends from a fluid inlet disposed at a first elevation with respect to the printing surface and the movable die includes a fiber inlet disposed at a second elevation with respect to the printing surface. The second elevation is larger than the first elevation, and receiving the spread dry fiber tows includes receiving the spread dry fiber tows at the fiber inlet of the movable die with the dry fiber tows extending generally parallel with respect to the longitudinal grooves. 
     In some implementations, wetting the spread fiber tows includes generally uniformly contacting the fiber tows with the molten polymer. 
     In some implementations, the movable die is coupled to an additive manufacturing actuator system configured to move the movable die along the printing surface. Depositing the layer of the wet fiber tows includes depositing layers of the wet fiber tows on the printing surface to form a preform object in a semi-consolidated state. 
     Implementations of the present disclosure include an apparatus for manufacturing thermoplastic components. The apparatus includes a fiber spreader configured to spread dry fiber tows, a polymer extruder, and a movable die fluidically coupled to the polymer extruder to receive molten polymer from the polymer extruder. The movable die receives the spread dry fiber tows from the fiber spreader. The movable die includes an internal grooved surface defining longitudinal grooves extending between an inlet of the movable die and an outlet of the movable die through which the fiber tows exit the movable die. The inlet receives the spread dry fiber tows from the fiber spreader. The movable die also includes an internal channel configured to flow the molten polymer from a fluid inlet of the internal channel to the dry fiber tows to wet the dry fiber tows. The longitudinal grooves help prevent the wet fiber tows from mingling as the wet fiber tows move along the longitudinal grooves to exit the movable die. The die deposits a layer of the wet fiber tows on a printing surface to form a thermoplastic component of one or more layers of fiber tows on the printing surface. 
     In some implementations, the grooves extend in a direction parallel to a moving direction of the spread dry fiber tows. The grooves extend from the inlet of the movable die to the outlet of the movable die. 
     In some implementations, the outlet includes a flat lip configured to level the surface of the layer of the wet fiber tows to deposit a layer of generally uniform thickness. 
     In some implementations, each longitudinal groove includes a width of about 500 to 1000 micrometers. 
     In some implementations, the movable die further includes a cover plate disposed on top of the grooved surface. The movable die maintains the spread fiber tows in the longitudinal grooves. In some implementations, the outlet of the movable die is defined between a first flat lip adjacent the grooved surface and a second flat lip opposing the first flat lip. The second flat lip extends from the cover plate. The second flat lip levels, with the first flat lip, the surface of the layer of the wet fiber tows to deposit a layer of generally uniform thickness. 
     In some implementations, the internal channel is disposed upstream of the internal grooved surface and extends parallel to the length of the longitudinal grooves. The internal channel flows the molten polymer into the internal grooved surface to flow along the longitudinal grooves to wet the dry fiber tows. 
     In some implementations, the internal channel extends from the fluid inlet of the movable die to the internal grooved surface. The inlet of the movable die is disposed downstream of the fluid inlet adjacent a first end of the internal grooved surface to direct the spread fiber tows toward the internal grooved surface. 
     In some implementations, the longitudinal grooves of the internal grooved surface extend from the inlet of the movable die to the outlet of the movable die. The internal channel is disposed at the internal grooved surface and extends laterally across the internal grooved surface. The internal channel flows the molten polymer across the longitudinal grooves to wet the dry fiber tows. In some implementations, the fluid inlet is disposed at a first elevation with respect to the printing surface and the inlet of the movable die is disposed at a second elevation with respect to the printing surface. The second elevation is larger than the first elevation, and the movable die is configured to receive the dry fiber tows extending generally parallel with respect to the longitudinal grooves. 
     In some implementations, the apparatus also includes an additive manufacturing actuator system coupled to the movable die. The additive manufacturing actuator system moves the movable die along the printing surface to lay layers of the wet fiber tows on the printing surface to form a preform object in a semi-consolidated state. 
     Implementations of the present disclosure also include a movable die that includes a grooved surface that defines longitudinal grooves extending between an inlet and an outlet of the movable die. The inlet receives spread dry fiber tows. The movable die also includes a fluid channel fluidically coupled to a fluid source configured to flow fluid into the fluid channel. The fluid channel flows the fluid to the dry fiber tows to contact the dry fiber tows with the fluid. The longitudinal grooves are configured to help maintain the spread fiber tows spread as the fiber tows move along the longitudinal grooves to exit the movable die. The movable die deposits a layer of the fiber tows on a surface to form a component of one or more layers of fiber tows on the surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side schematic view of a printing system according to a first implementation of the present disclosure. 
         FIG. 2  is a front schematic view of the printing system of  FIG. 1 . 
         FIG. 3  is a perspective exploded view of a grooved die of the printing system of  FIG. 1 . 
         FIG. 4A  is a top view of a first portion of the grooved die of  FIG. 3 . 
         FIG. 4B  is a top view of a second portion of the grooved die of  FIG. 3 . 
         FIG. 5  is a front schematic view of a printing system according to a second implementation of the present disclosure. 
         FIG. 6  is a perspective exploded view of a grooved die of the printing system of  FIG. 5 . 
         FIG. 7A  is a top view of a first portion of the grooved die of  FIG. 6 . 
         FIG. 7B  is a top view of a second portion of the grooved die of  FIG. 6 . 
         FIG. 8  is a flow chart of an example method of manufacturing thermoplastic components. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The present disclosure describes a grooved die for a printing apparatus used to manufacture thermoplastic components. The grooved die receives spread fiber tows and wets the fiber tows with molten polymer before depositing layers of the wet fiber tows on a printing surface. The grooved die is connected to an additive manufacturing actuator system that moves the grooved die to deposit layers of the wet fiber tows on the printing surface to form two-dimensional thermoplastic components. The grooved die defines longitudinal grooves that help maintain the fiber tows spread as the fiber tows move along the die. 
     Particular implementations of the subject matter described in this specification can be implemented so as to realize one or more of the following advantages. For example, using a grooved die in a printing apparatus allows thermoplastic layers to be deposited with the fibers separated, ensuring fibers wettability, fibers uniformity, and increasing the quality of the final product. 
       FIGS. 1 and 2  show a printing apparatus or system  100  for manufacturing thermoplastic components  130 . The thermoplastic components  130  can be, for example, thermoplastic preforms in a semi-consolidated state. The printing apparatus  100  includes a grooved die  102  (for example, a movable die), a polymer extruder  104  fluidically coupled to the grooved die  102 , one or more fiber spreaders  106  that spread dry fiber tows  108 , a printing surface  114  (for example, a printing bed), and an additive manufacturing actuator system  120  (for example, a gantry or a multi-axis robotic system) coupled to the die  102 . As shown in  FIG. 1 , the additive manufacturing actuator system  120  includes one or more actuators  118  (for example, linear actuators) and a processing device  128  (for example, a computer) communicatively coupled to the actuators  118 . The processing device  118  has additive manufacturing software to control the actuators  118  to move the grooved die  102  along the printing surface  114  to deposit layers  131  of wet fiber tows  108  on the printing surface  114 . The grooved die  102  can deposit layers  131  to form two-dimensional or three-dimensional thermoplastic components  130 . For example, the grooved die  102  can print or form preform objects in a semi-consolidated state. 
     Referring to  FIG. 2 , the fiber spreader  106  spreads the fiber tows  108  from bundled fiber tows  108   a  to a continuous warp of spread fiber tows  108   b . The fiber tows  108  can be made, for example, of carbon fiber. As shown in  FIG. 1 , the spread fiber tows  108   b  enter the die  102  through a side opening or inlet  162  to be wetted with a melted polymer  110  (for example, a matrix material such as an epoxy resin) inside the grooved die  102 . The wet fiber tows  10  are deposited on the printing surface  114  by the die  114  to form layers of unidirectional tape (UD tape). 
     Referring to  FIG. 1 , the grooved die  102  has an interior channel  112  fluidically coupled to the polymer extruder  104  to receive the molten polymer  110  from the polymer extruder  104 . The fiber tows  108  enter the interior channel  112  to be wetted with the polymer  110  and then exit the die  102  through an exit or outlet  124  of the grooved die  102 . The molten polymer  110  flows along the channel toward the spread fiber tows  108  to wet or impregnate the fiber tows  108  at the interior channel  112 . The wet fiber tows  108  form a layer  131  of continuous UD tape that the die  102  lays or deposits on the printing surface  114 . The grooved die  102  forms thermoplastic components  130  with multiple layers  131  of continuous UD tape. For example, the grooved die  102  deposits the first layer and then waits for the layer to dry and stick to the printing surface  114 . The dry layer acts as an anchor to pull the subsequent fiber layers during the tape laying process. The grooved die  102  moves along the printing surface  114  to form thermoplastic components  130  of one or more layers  131  of wet fiber tows on the printing surface  114 . 
       FIG. 3  shows an exploded view of the grooved die  102 . The grooved die  102  has a first plate  152  attached to a cover plate  150  disposed on top of (or adjacent to) the first plate  152 . The first plate  152  has an internal grooved surface  170  that defines longitudinal grooves  171  extending between an inlet  162  of the grooved die and the outlet  124  of the grooved die through which the fiber tows exit the grooved die  102 . The inlet  162  receives the spread dry fiber tows from the fiber spreader. The spread fiber tows  108  are directed by the inlet  162  to the grooved surface  170  to move the spread fiber tows along the grooved surface  170  in a direction parallel to a length of the longitudinal grooves  171 . Specifically, the longitudinal grooves  171  extend in a direction parallel to a moving direction of the spread dry fiber tows  108   b  (see  FIG. 1 ). The grooved die  102  also includes an internal fluid channel  112  that flows the molten polymer from a fluid inlet  190  of the internal channel  112  to the internal grooved surface  170  to wet the dry fiber tows. The longitudinal grooves  171  help prevent the wet fiber tows  108  from mingling as the wet fiber tows move along the longitudinal grooves  171  to exit the grooved die  102 . In some implementations, the grooved surface  170  can extend beyond the inlet  162  into the grooved die  102 . 
     The outlet  124  of the grooved die  102  has at least one flat lip  182  that levels the surface of the layer  131  of the wet fiber tows to deposit the layer  131  having a generally uniform thickness. The first flat lip  182  has a flat surface  181  downstream of the grooved surface  170  to flatten the layer  131  of wet fiber tows as the layer exits the grooved die  102 . The cover plate  150  can have a second flat lip  180  opposed to the first flat lip  182 . The second flat lip  180  defines, together with the first flat lip  181  of the first plate  152 , the outlet  124  (for example, a longitudinal gap) of the grooved die  102 . The second flat lip  180  extends from the cover plate  150  and levels, with the first flat lip  181 , the surface of the layer  131  of the wet fiber tows to deposit a layer of generally uniform thickness. 
     The cover plate  150  is disposed on top of the grooved surface  170  to maintain the spread fiber tows  108   b  in the longitudinal grooves  171  to move along and within the longitudinal grooves  171 . Each longitudinal groove  171  has a width of about 500 to 1000 micrometers to receive one or multiple fibers. 
     As shown in  FIG. 4A , the internal fluid channel  112  is disposed upstream of the internal grooved surface  170  and extends in a direction parallel to the length of the longitudinal grooves  171  to flow the molten polymer generally along the direction of the longitudinal grooves  171 . By upstream, it is meant that the fluid channel  112  is disposed in an opposite direction or location, with respect to the outlet  124 , from the direction in which the molten polymer  110  flows. The internal channel  112  flows the molten polymer to the internal grooved surface  170  to flow along the longitudinal grooves  171  to wet the dry fiber tows  108 . The fluid inlet  190  of the channel  112  has a width smaller than a width of the grooved surface  170 . Thus, the channel increases in width toward the grooved surface  170  to spread or distribute the molten polymer. In some implementations, the channel  112  can include a distribution manifold (not shown) to evenly distribute the molten polymer to evenly wet the spread fiber tows  108 . As shown in  FIGS. 4A and 4B , the inlet  162  of the grooved die  102  is disposed downstream of the fluid inlet  190 . The inlet  162  is adjacent a first end  173  of the internal grooved surface  170  to direct the spread fiber tows, starting from the first end  173 , toward the internal grooved surface  170 . 
       FIG. 5  shows a printing apparatus  200  according to a second implementation of the present disclosure. The printing apparatus  200  includes a grooved die, a polymer extruder  204  fluidically coupled to the grooved die  202 , and one or more fiber spreaders  206  that spread dry fiber tows  208   a  to a continuous warp of spread fiber tows  208   b . Similar to the printing apparatus of  FIG. 1 , the printing apparatus  200  also includes a printing surface and an additive manufacturing actuator system coupled to the die  202 . The printing apparatus  200  has a grooved die  202  with a grooved surface  270  that spans a length of the grooved die  202 . The printing apparatus  200  is similar to the printing apparatus of  FIG. 1 , with the main exception that the grooved die  202  receives the spread dry fiber tows  208  from a top inlet  262  rather than a side inlet. 
     Referring to  FIG. 6 , the grooved die  202  has a grooved surface  270  that defines longitudinal grooves  271  that extend from the inlet  262  of the grooved die  202  to the outlet  224  of the grooved die  202 . As shown in  FIG. 7A , the internal fluid channel  210  of the grooved die  202  is disposed at the internal grooved surface  270  and extends generally laterally across the internal grooved surface  270 . The internal fluid channel  210  flows the molten polymer across the longitudinal grooves  271  to wet the dry fiber tows  208  as the fiber tows move along the longitudinal grooves  271 . The fluid channel has a fluid inlet  290  that is disposed at a first elevation with respect to the printing surface (or with respect to the outlet  224  of the grooved die  202 ). The inlet  262  of the grooved die  202  is disposed at a second elevation with respect to the printing surface. The second elevation is larger or higher than the first elevation. The grooved die  202  receives the dry fiber tows extending generally parallel with respect to the longitudinal grooves  270 . 
     The present disclosure includes a method  800  of manufacturing thermoplastic components. The method includes receiving, by a movable die including an internal grooved surface including a plurality of longitudinal grooves, spread dry fiber tows ( 805 ). The method also includes receiving, by the movable die and from a polymer extruder fluidically coupled to the movable die, molten polymer ( 810 ). The method also includes wetting, by the movable die, the spread fiber tows with the molten polymer ( 815 ). The method also includes moving, by the movable die, the wet fiber tows along the plurality of longitudinal grooves in a direction parallel to a length of the longitudinal grooves, the longitudinal grooves configured to help prevent the wet fiber tows from mingling as the wet fiber tows move along the longitudinal grooves to exit the movable die ( 820 ). The method also includes depositing, by the movable die, a layer of the wet fiber tows on a printing surface, the movable die configured to move along the printing surface to form a thermoplastic component of one or more layers of fiber tows on the printing surface ( 825 ). 
     Although the following detailed description contains many specific details for purposes of illustration, it is understood that one of ordinary skill in the art will appreciate that many examples, variations and alterations to the following details are within the scope and spirit of the disclosure. Accordingly, the exemplary implementations described in the present disclosure and provided in the appended figures are set forth without any loss of generality, and without imposing limitations on the claimed implementations. 
     Although the present implementations have been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the disclosure. Accordingly, the scope of the present disclosure should be determined by the following claims and their appropriate legal equivalents. 
     The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise. 
     As used in the present disclosure and in the appended claims, the words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. 
     As used in the present disclosure, terms such as “first” and “second” are arbitrarily assigned and are merely intended to differentiate between two or more components of an apparatus. It is to be understood that the words “first” and “second” serve no other purpose and are not part of the name or description of the component, nor do they necessarily define a relative location or position of the component. Furthermore, it is to be understood that that the mere use of the term “first” and “second” does not require that there be any “third” component, although that possibility is contemplated under the scope of the present disclosure.