Manufacturing apparatus and method of forming a preform

The present invention provides for a manufacturing apparatus for forming a ceramic preform from an extrudate having a first end and a second end. A cutter forms the first and second ends of the extrudate complementary to each other such that the first and second ends of the extrudate align with each other in a spaced relationship to define a preform having a substantially uniform exterior surface and a substantially uniform thickness. The present invention provides for a method of forming the preform from the extrudate having the first and second ends utilizing a mandrel. The method includes the step of aligning the second end complementary to the first end of the first layer in a spaced relationship to define the preform having the substantially uniform exterior surface and the substantially uniform thickness.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a manufacturing apparatus and a method of forming a preform.

2. Description of the Related Art

Manufacturing preforms, such as ceramic preforms, are known in industry. However, current methods for manufacturing ceramic preforms are accomplished through a manual batch mixing process and then manual formation of the desired configuration. Traditionally, preforms shaped as a cylinder are hand formed from a composition. A metal wire is disposed about the preform for strengthening the preform. More specifically, the composition used to produce the preform does not meet the strength requirements for the final preform. As such, the metal wire is required to add strength to the final preform. Preforms having the metal wire as discussed above is disclosed in U.S. Pat. No. 6,530,458.

Therefore, there remains an opportunity to develop a manufacturing apparatus and a method of forming a preform.

SUMMARY OF THE INVENTION

The present invention provides for a manufacturing apparatus for forming a ceramic preform from an extrudate having a first end and a second end. The apparatus includes a multi-screw extruder including at least three intermeshing screws for forming the extrudate. The apparatus also includes a mandrel defining an outer diameter for wrapping the extrudate about the outer diameter to define a plurality of layers disposed on top of each other such that the extrudate defines an inner diameter complementary to the outer diameter of the mandrel. The apparatus further includes a pressure-applying device adjacent the mandrel for applying pressure to the layers of the extrudate. In addition, the apparatus includes a cutter for forming the first and second ends of the extrudate complementary to each other such that the first and second ends of the extrudate align with each other in a spaced relationship to define a preform having a substantially uniform exterior surface and a substantially uniform thickness.

The present invention also provides for a method of forming a preform from an extrudate having a first end and a second end utilizing a mandrel. The method includes the steps of forming the first end of the extrudate, wrapping the extrudate about the mandrel to form a first layer having the first end abutting the mandrel, and applying pressure to the first layer during wrapping of the extrudate about the mandrel. The method further includes the steps of forming the second end of the extrudate complementary in configuration to the first end, wrapping the extrudate about the mandrel to form a second layer on top of the first layer with the second end spaced from the mandrel, and applying pressure to the second layer during wrapping of the extrudate about the mandrel. The method also includes the step of aligning the second end complementary to the first end of the first layer in a spaced relationship to define the preform having a substantially uniform exterior surface and a substantially uniform thickness.

The present invention further provides a method of forming a ceramic preform comprising ceramic particles and ceramic fibers having an aspect ratio of greater than or equal to 10:1 and the ceramic fibers substantially randomly orientated in three dimensions utilizing a mandrel and an extruder. Said differently, greater than 90 out of 100 ceramic fibers are randomly oriented in three dimensions in said ceramic article. The method includes the step of extruding the ceramic particles and the ceramic fibers through the extruder to form an extrudate having a first end and a second end. The method also includes the steps of forming the first end of the extrudate, wrapping the extrudate about the mandrel to form a first layer having the first end abutting the mandrel, and applying pressure to the first layer during wrapping of the extrudate about the mandrel. The method further includes the steps of forming the second end of the extrudate complementary in configuration to the first end, wrapping the extrudate about the mandrel to form a second layer on top of the first layer with the second end spaced from the mandrel, and applying pressure to the second layer during wrapping of the extrudate about the mandrel. In addition, the method includes the step of aligning the second end complementary to the first end of the first layer in a spaced relationship to define the preform having a substantially uniform exterior surface and a substantially uniform thickness.

Therefore, the present invention provides for the manufacturing apparatus that allows for an automated production of the preforms thus providing a more efficient process. Wrapping the layers on top of each other provides for the preform to be easily formed of a desired thickness. Additionally, the layers are easily integrated or blended together when the layers are disposed on top of each other. Further, the second end provides one small seam to be integrated or blended into the respective layer. Also, the preform as described herein is easily removable from the mandrel without being damaged and is resistant to cracking.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a manufacturing apparatus20for forming a ceramic article or preform22from an extrudate24is generally shown inFIG. 1. More specifically, the manufacturing apparatus20is utilized for forming a ceramic preform22from the extrudate24.

The manufacturing apparatus20includes a multi-screw extruder26for processing a composition for forming the extrudate24. In other words, the composition is mixed in the multi-screw extruder26for forming the extrudate24. The composition generally comprises ceramic particles and ceramic fibers having an aspect ratio of greater than or equal to 10:1. The ceramic fibers are substantially randomly orientated in three dimensions. It is to be appreciated that the composition can be manufactured from materials other than ceramic particles and ceramic fibers. The composition will be discussed further below.

The multi-screw extruder26includes at least three intermeshing screws28for processing the composition to form the extrudate24. The at least three intermeshing screws28are formed in a ring configuration. More specifically, the at least three intermeshing screws28are generally arranged in a fixed ring configuration and geared to a common motor. In one embodiment, the at least three intermeshing screws28are further defined as twelve intermeshing screws28which are formed in the ring configuration. The screws28also rotate at a common speed as is known in the industry. The screws28can be co-rotating or counter-rotating. In addition, the screws28can be self-wiping. It is to be appreciated that the screws28can be any suitable configuration and can rotate as desired.

Processing the composition for forming or extruding the extrudate24can be further defined as rotating the at least three intermeshing screws28at about 20 to 1,200 rpm and more specifically about 100 to 400 rpm. As the intermeshing screws28rotate, the composition is conveyed, mixed, and advanced through the multi-screw extruder26until the composition exits the multi-screw extruder26.

The multi-screw extruder26has a modular design and comprises solid barrels and/or combination barrels. The combination barrels include ports for injecting materials and/or for venting volatile gases. It is to be appreciated that one skilled in the art can select a combination of solid barrels and combination barrels to provide desired mixing characteristics of the multi-screw extruder26and desired physical properties of the extrudate24.

The multi-screw extruder26can also include flow blocking flights for providing separate mixing processes in the multi-screw extruder26. The flow blocking flights can be flighted and can impede passing of the composition between sections of the multi-screw extruder26. It is to be appreciated that certain flow blocking flights can be removed for increasing the feeding capability of the multi-screw extruder26.

The multi-screw extruder26has 2 to 8 mixing zones, and in one embodiment has 4 to 6 mixing zones. It is to be appreciated that the multi-screw extruder26can have more or less mixing zones as desired. The multi-screw extruder26also has an L/D ratio of from about 18 to 56, and in one embodiment has an L/D ratio of from about 20 to 44. A suitable multi-screw extruder26is a 3+ RingExtruder commercially available from Century, Inc. of Traverse City, Mich.

The multi-screw extruder26generally elongates and shears the composition to provide distributive and dispersive mixing to both randomly orient the ceramic fibers in three dimensions and homogeneously distribute dispersed the ceramic fibers. Extruding the composition generally includes arranging adjacent the ceramic fibers in different dimensions so that adjacent ceramic fibers arranged in different dimensions are present in the extrudate24in an amount of greater than 85 parts by volume based on 100 parts by volume of the extrudate24. In one embodiment, greater than 85 parts by volume of the ceramic fibers are uniformly distributed on a scale of twice the diameter of the ceramic fibers. That is, the multi-screw extruder26provides excellent elongational and low-intensity shear mixing that results in adjacent ceramic fibers oriented in different dimensions in the extrudate24.

The multi-screw extruder26can also mix an organic binder into the composition. In one embodiment, the organic binder comprises cellulose ether. Cellulose ether generally exhibits reverse thermal gelation and provides lubricity during formation of the preform22. Without intending to be limited by theory, it is believed that the cellulose ether also provides surface activity, plasticity, uniform rheology, strength, and uniform distribution of air during formation of the preform22. Cellulose ether is generally selected from the group of methyl cellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose, and combinations thereof. One example of a suitable methyl cellulose is hydroxypropylmethylcellulose, commercially available under the trade name Methocel™ A4M from The Dow Chemical Company of Midland, Mich. It is to be appreciated that any suitable organic binder can be utilized.

The multi-screw extruder26can also mix a filler into the composition. It is to be appreciated that one skilled in the art can select the filler to control the density of the extrudate24. That is, the filler is included in the composition according to the weight percent of the ceramic particles and the ceramic fibers in the composition. The filler generally spaces out the ceramic particles and the ceramic fibers to provide the extrudate24and the preform22with the desired density and/or to allow effective metal infiltration during any secondary processing of the preform22, such as infiltrating the preform22with a metal. The filler is selected to burn off during heating of the extrudate24or preform22as discussed further below. The filler can be selected from walnut shell flour, cellulose fiber, air, and combinations thereof. One example of a suitable filler is walnut shell flour, commercially available under from Ecoshell of Corning, Calif. It is to be appreciated that any suitable filler can be utilized.

The multi-screw extruder26can also mix an inorganic binder into the composition. In one embodiment, the inorganic binder is silica. Without intending to be limited by theory, it is believed that the inorganic binder provides the preform22with strength. One example of a suitable inorganic binder is silica, commercially available under the trade name Bindzil 1440 Colloidal Silica from Wesbond Corporation of Wilmington, Del. It is to be appreciated that any suitable inorganic binder can be utilized.

The multi-screw extruder26includes an exiting end30having a die plate32coupled to the exiting end30of the multi-screw extruder26. The composition is defined as the extrudate24once the composition has been processed in and exits the multi-screw extruder26. As such, once the composition exits the exiting end30of the multi-screw extruder26, the composition will be referred to as the extrudate24. The die plate32shapes the extrudate24in a desired configuration as the composition exits the multi-screw extruder26. More specifically, the die plate32defines a bore34of the desired configuration for allowing the composition to pass through the die plate32to form the desired configuration of the extrudate24. As the composition exits the multi-screw extruder26, the composition is forced through the bore34of the die plate32. The extrudate24moves away from the multi-screw extruder26in a first direction as indicated inFIG. 1. The extrudate24defines a continuous piece of extrudate24as the extrudate24exits the exiting end30of the multi-screw extruder26. For example, the extrudate24can define a generally rectangular cross-section when exiting the die plate32. It is to be appreciated that the extrudate24can be any suitable configuration.

Generally, the extrudate24defines an initial temperature of from about 50 to 100 degrees Fahrenheit as the extrudate24exits the multi-screw extruder26. In other words, the composition or extrudate24exits the multi-screw extruder26at the initial temperature of from about 50 to 100 degrees Fahrenheit.

Referring toFIGS. 2-5, the extrudate24has a first end36defining a first configuration and a second end38defining a second configuration with the first and second ends36,38spaced from each other. In addition, the extrudate24includes a first side40and a second side42opposing the first side40. The extrudate24defines the continuous piece of extrudate24between the first and second ends36,38. The first configuration and the second configuration are each angled such that the first and second ends36,38complement each other. More specifically, as best shown inFIG. 5, the first end36of the extrudate24defines a first angle α relative to the first side40and the second end38of the extrudate24defines a second angle β relative to the second side42. The first and second ends36,38can be cut at any suitable angle, such as, for example, approximately 45 degrees or less. In one embodiment, the first and second angles α, β are each defined as of from about 30 to 45 degrees. In another embodiment, the first and second angles α, β are each defined as less than 45 degrees. The first and second ends36,38of the extrudate24complement each other such that the first and second ends36,38align with each other in a spaced relationship which is discussed further below. It is to be appreciated that the first and second angles α, β have been exaggerated for illustrative purposes only.

As best shown inFIGS. 2-4,6, and7, the manufacturing apparatus20also includes a mandrel44adjacent the multi-screw extruder26for wrapping the extrudate24about the mandrel44. More specifically, the mandrel44is rotatable about a longitudinal axis L transverse to the first direction. Also referring toFIG. 11, the mandrel44defines an outer diameter OD for wrapping the extrudate24about the outer diameter OD to define a plurality of layers46disposed on top of each other such that the extrudate24defines an inner diameter ID complementary to the outer diameter OD of the mandrel44.

A bracket48is disposed adjacent the multi-screw extruder26for rotatably supporting the mandrel44. The bracket48can be any suitable configuration for supporting the mandrel44. A pivot47is coupled to the bracket48and disposed along the longitudinal axis L with the mandrel44concurrently rotatable with the pivot47about the longitudinal axis L. It is to be appreciated that the mandrel44can rotate independently of the pivot47.

A clamp49selectively engages one end of the pivot47for securing the mandrel44to the pivot47. The pivot47and the clamp49cooperate for allowing the mandrel44to be easily removable from the pivot47and the bracket48, thus automating production of the preform22. In addition, a motor51is coupled to the pivot47for rotating the mandrel44about the longitudinal axis L. The motor51rotates the pivot47which causes the mandrel44to rotate about the longitudinal axis L. It is to be appreciated that the motor51can be any suitable horsepower and configuration for rotating the mandrel44.

The mandrel44includes an outer surface50spaced radially from the longitudinal axis L for wrapping the extrudate24about the outer surface50of the mandrel44. The extrudate24is wrapped about the mandrel44to form a first layer52. More specifically, as the mandrel44rotates about the longitudinal axis L, the first side40of the first layer52abuts the outer surface50of the mandrel44. The extrudate24can continue to be wrapped about the mandrel44to form a second layer54on top of the first layer52. As such, the first side40of the second layer54abuts the second side42of the first layer52as the mandrel44continues to rotate about the longitudinal axis L. Further, the extrudate24can continue to be wrapped about the mandrel44to form a third layer56on top of the second layer54. Therefore, the first side40of the third layer56abuts the second side42of the second layer54. Hence, the first52, second54, and third56layers overlap each other. As alluded to above, the layers46, and hence, the first52, second54, and third56layers, each include the first and second sides40,42. Simply stated, the layers46, such as the first52, second54, and third56layers, are wrapped on the outer surface50of the mandrel44as the mandrel44rotates about the longitudinal axis L. It is to be appreciated that one or more layers46can be wrapped about the mandrel44. It is to further be appreciated that any suitable number of layers46can be wrapped about the mandrel44.

With the first end36of the first layer52defining the first angle α, the second layer54ramps up over the first end36of the first layer52and overlaps the first layer52. Similarly, when utilizing the third layer56, the third layer56ramps up over the first end36in a spaced relationship and overlaps the second layer54. As such, the first and second ends36,38of the extrudate24complement each other such that the first and second ends36,38of the extrudate24align with each other in a spaced relationship. Generally, having the first and second ends36,38spaced from each other with at least one layer46disposed between the first and second ends36,38minimizes cracking of the preform22. Each of the layers46define approximately one revolution about the mandrel44. Therefore, for example, the extrudate24is wrapped about the mandrel44approximately three times to form the first52, second54, and third56layers.

In addition, the manufacturing apparatus20includes a cutter58for forming the first and second ends36,38of the extrudate24complementary to each other such that the first and second ends36,38of the extrudate24align with each other in a spaced relationship to define the preform22having a substantially uniform exterior surface60and a substantially uniform thickness T. The first and second ends36,38are cut to align with each other in a spaced relationship to define the preform22. The exterior surface60of the preform22is an exposed side of the last layer52,54,56. The substantially uniform thickness T is the total combined thickness T of the layers52,54,56as identified inFIGS. 6 and 7. Further, having the substantially uniform thickness T of the preform22also minimizes cracking of the preform22.

Turning toFIGS. 2-4, when the process of creating the extrudate24begins, the extrudate24exiting the die plate32must be cut to form the first end36defining the first angle α. For example, a portion of the first layer52is disposed on the outer surface50of the mandrel44and then the first layer52is cut to form the first end36defining the first angle α. It is to be appreciated that the first end36of the first layer52can be cut before being disposed on the outer surface50of the mandrel44. It is to be appreciated that the first and second ends36,38can be cut by any suitable machine, device, apparatus, by hand, etc. For example, the cutter58can be defined as a knife, etc. As such, in one embodiment, the extrudate24is cut by hand with the knife.

When the second end38is cut to define the second angle β, the preform22and the mandrel44are ready for the next step of the process, and therefore, are ready to be removed from the bracket48. Another mandrel can be rotatably coupled to the bracket48for forming another preform, and so on. In other words, once the extrudate24is wrapped about the mandrel44to the desired number of layers46and the second end38is cut, the mandrel44and the preform22can be removed from the bracket48and replaced by another mandrel for repeating the process of wrapping the extrudate24about the second mandrel to form a second preform, etc. Therefore, cutting the second end38of the previous preform22is also the first end36of the next preform. In other words, cutting the second end38to the second angle β for the previous preform22also creates the first angle α of the first end36of the next preform. It is to be appreciated that the first end36can be re-cut if desired when starting the next preform.

The second end38of the preform22defines a seam62on the exterior surface60of the preform22. As such, once the second end38is cut, the second end38or seam62is adhered and/or leveled into the second side42of the last layer52,54,56to further define the substantially uniform exterior surface60. Further, the second end38or seam62is blended or massaged into the second side42of the last layer52,54,56to integrate or combine the second end38into the last layer52,54,56. In other words, the ceramic particles and ceramic fibers, etc. of the second end38of one layer52,54,56is blended/integrated with the ceramic particles and ceramic fibers, etc. of another layer52,54,56.

The extrudate24defines the preform22when the desired number of layers46are wrapped about the mandrel44and the second end38is cut. For example, if two layers46are desired, the first and second layers52,54define the preform22once the second end38is cut with the second side42of the second layer54being the exposed side and thus defining the exterior surface60of the preform22. As another example, if three layers46are desired, the first52, second54, and third56layers define the preform22once the second end38is cut. Hence, if three layers46are desired to define the preform22, the first52, second54, and third56layers are wrapped on top of each other on the mandrel44with the second side42of the third layer56being the exposed side and thus defining the exterior surface60of the preform22. The second end38can be blended or massaged to smooth the last layer52,54,56and/or decrease the visibility of the second end38, etc. It is to be appreciated that the desired number of layers46wrapped about the mandrel44are one continuous piece of extrudate24.

A first substance can be applied to the first and second ends36,38for increasing adhesion of the extrudate24. The first substance is applied to the first end36prior to wrapping the extrudate24about the mandrel44. Likewise, the first substance is applied to the second end38after wrapping the extrudate24about the mandrel44. It is to be appreciated that the first substance can be applied to any of the layers46of the extrudate24. It is also to be appreciated that the first substance can be of any suitable composition, including water, to increase adhesion.

The mandrel44is cooled to a first temperature for adhering the extrudate24to the mandrel44. In other words, the mandrel44is cooled such that the extrudate24sticks to the mandrel44. More specifically, the mandrel44is cooled such that the first side40of the first layer52adheres to the outer surface50of the mandrel44. Having the extrudate24adhere or stick to the mandrel44allows the first layer52to remain attached to the outer surface50of the mandrel44as the mandrel44rotates about the longitudinal axis L. Generally, the first temperature of the mandrel44is below room temperature. In one embodiment, the first temperature of the mandrel44is above 40 and below 70 degrees Fahrenheit. In another embodiment, the first temperature of the mandrel44is of from about 40 to 60 degrees Fahrenheit. In yet another embodiment, the first temperature of the mandrel44is of from about 40 to 50 degrees Fahrenheit.

The mandrel44is formed of a metal material. In certain embodiments, the metal material of the mandrel44is an alloy. Suitable alloys include aluminum and/or iron alloys. It is to be appreciated that the mandrel44can be formed of other material(s).

The outer surface50of the mandrel44includes a first edge64and a second edge66spaced from each other with the outer diameter OD defined between the first and second edges64,66. The outer surface50of the mandrel44defines an angle γ relative to a plane P parallel to the longitudinal axis L. In one embodiment, the angle γ of the outer surface50is 0 degrees such that the outer surface50is substantially flat as shown inFIG. 6. Hence, the outer diameter OD of the mandrel44remains the same between the first and second edges64,66.

In another embodiment, the angle γ of the outer surface50is greater than 0 degrees and less than 3 degrees such that the outer surface50is substantially tapered as shown inFIGS. 7 and 8. Hence, the outer diameter OD of the mandrel44changes between the first and second edges64,66. In other words, the outer diameter OD of the mandrel44increases from one of the first and second edges64,66to the other one of the first and second edges64,66. As shown in the embodiment ofFIGS. 7 and 8, the outer diameter OD of the mandrel44adjacent the first edge64is less than the outer diameter OD of the mandrel44adjacent the second edge66with the outer diameter OD gradually increasing from the first edge64toward the second edge66. In certain embodiments, the angle γ of the outer surface50is further defined as of from about 0.5 to 2.0 degrees. In one embodiment, the angle γ of the outer surface50is defined as 0.75 degrees. It is to be appreciated that the angle γ of the outer surface50can be any suitable degree. In addition, it is to be appreciated that the angle γ of the outer surface50when tapered and thus the corresponding inner diameter ID of the preform22, as well as the exterior surface60of the preform22, have been exaggerated for illustrative purposes only.

Having the outer surface50of the mandrel44being tapered, aids in releasing or removing the preform22from the mandrel44. In other words, the changing outer diameter OD of the outer surface50improves the ability to release or remove the preform22from the mandrel44. Utilizing the mandrel44including the outer surface50having the taper reduces frictional engagement between the preform22and the mandrel44as the preform22is removed from the mandrel44. More specifically, sliding friction is progressively reduced as the preform22separates from the mandrel44when utilizing the mandrel44including the outer surface50having the taper. To remove the preform22from the mandrel44when the outer surface50is tapered, the preform22is removed over the first edge64until the preform22is completely removed from the mandrel44. In other words, the preform22is removed from the first edge64of the mandrel44defining the smaller outer diameter OD. As the preform22moves relative to the mandrel44, the inner diameter ID of the preform22becomes spaced from the outer diameter OD of the mandrel44due to the taper and thus frictional engagement between the preform22and the mandrel44is reduced. Generally, the preform22is removed from the mandrel44after the preform22has been dried as discussed further below.

As best shown inFIGS. 1,3,4, and9, the manufacturing apparatus20further includes a pressure-applying device68adjacent the mandrel44for applying pressure to the layers46of the extrudate24. More specifically, the pressure-applying device68applies pressure to the layers46as the mandrel44rotates about the longitudinal axis L. Hence, the pressure-applying device68engages the extrudate24for applying pressure to the extrudate24to adhere and/or level the layers46to further define the substantially uniform thickness T. For example, when utilizing three layers46, the pressure-applying device68applies pressure to the first52, second54, and third56layers as the mandrel44rotates about the longitudinal axis L, thus blending, integrating, or combining the second layer54to the first layer52and blending, integrating, or combining the third layer56to the second layer54. In other words, the ceramic particles and ceramic fibers, etc. of one layer52,54,56are blended/integrated with the ceramic particles and ceramic fibers, etc. of another layer52,54,56. Further, the pressure-applying device68levels each of the layers46and/or levels the exterior surface60of the preform22to further defining the substantially uniform exterior surface60. Generally, pressure is applied after the first end36of the first layer52is disposed on the mandrel44and/or after the first end36is cut to the first angle α. The application of pressure to level the extrudate24ensures a strong bond between the layers46that abut each other.

The pressure-applying device68can be disposed adjacent the mandrel44. Further, the pressure-applying device68can be attached to the bracket48or spaced from the bracket48as shown inFIGS. 1 and 9. A brace70is disposed adjacent the mandrel44for supporting the pressure-applying device68. The brace70can be coupled to the pivot47and/or attached to the bracket48. The pressure-applying device68is shown schematically and can be of any suitable configuration.FIGS. 1,3, and4illustrate one configuration of the pressure-applying device68andFIG. 9illustrates another configuration of the pressure-applying device68.

The pressure-applying device68includes a shaft72rotatable about a central axis C with at least one support76mounted to the shaft72. In certain embodiments, the support76is further defined as a plurality of supports76mounted to the shaft72and spaced from each other. As such, rotation of the support72about the central axis C also causes concurrent rotation of the support(s)76about the central axis C. It is to be appreciated that the pressure-applying device can include a sleeve (not shown) disposed about the shaft72and rotatable about the central axis C. The sleeve is attached to the shaft72such that the shaft72and the sleeve concurrently rotate about the central axis C and/or tilt as discussed below. As such, if utilizing the sleeve, the support(s)76are mounted to the sleeve. It is to be appreciated that the support(s)76can be mounted to the shaft72or the sleeve by any suitable method, such as for example, welding, press fit, adhesive, fasteners, etc.

In various embodiments, as shown inFIGS. 1,3,4, and9, the pressure-applying device68includes a roller78engaging the layers46with the roller78being rotatable. As shown inFIGS. 1,3, and4, the roller78is coupled to the support(s)76such that the roller78is rotatable relative to the support(s)76. Hence, the roller78is coupled to the shaft72through the support(s)76. The roller78rotates as the roller78engages the extrudate24or the layers46. In other words, the roller78rotates during engagement of the extrudate24or the layers46as the extrudate24is wrapped about the mandrel44. The roller78can also concurrently rotate with the support(s)76and the shaft72about the central axis C such that the roller78moves up and/or down relative to the extrudate24or the layers46to compensate for variances of the extrudate24or the layers46. As such, the roller78is allowed to float or adjust as the extrudate24is wrapped about the mandrel44.

Further, turning toFIG. 12, the roller78can rotate with the support(s)76and the shaft72about the central axis C for preventing the roller78from engaging the mandrel44when preparing to wrap the layers46. In addition, the roller78can rotate with the support(s)76and the shaft72about the central axis C for preventing the roller78from engaging the preform22when preparing to remove the mandrel44and the preform22from the pivot47or when preparing to couple the mandrel44to the pivot47. As such, the shaft72defines a slot80with a pin82disposed through the brace70and in the slot80for securing the roller78out of engagement from the mandrel44or the preform22. In other words, the pin82engages the slot80for maintain the roller78in an upward position for preventing the roller78from engaging the mandrel44or the preform22. It is to be appreciated that the roller78can be secured out of engagement from the mandrel44or the preform22by any suitable method.

In one embodiment, an amount of pressure being applied to the layers46can be adjusted by changing the weight of the roller78. In another embodiment, the amount of pressure being applied to the layers46can be adjusted by coupling a weight to the roller78. More specifically, at least one post84extends from one of the support(s)76for coupling one or more weights to the post84. The post84can be further defined as a plurality of posts84with one of the posts84extending from one of the supports76and another one of the posts84extending from another one of the supports76. It is to be appreciated that the posts84and the supports76supporting the posts84are spaced from the roller78for allowing the roller78to rotate without interference from the posts84or the supports76.

The pressure-applying device68is disposed complementary to the outer surface50of the mandrel44for engaging the layers46. More specifically, when utilizing the three layers46, the pressure-applying device68engages the first52, second54, and third56layers as the mandrel44rotates about the longitudinal axis L. Specifically, the roller78is disposed complementary to the outer surface50of the mandrel44for engaging the layers46or the extrudate24.

The pressure-applying device68includes an adjuster86for complementing the outer surface50of the mandrel44. As such, the adjuster86allows the pressure-applying device68to remain substantially parallel to the outer surface50of the mandrel44. In other words, the adjuster86allows the roller78to adjust in light of the configuration of the outer surface50of the mandrel44. Therefore, the adjuster86allows the pressure-applying device68, and more specifically, the roller78, to be substantial parallel to the outer surface50when flat or tapered while allowing the roller78to apply pressure to the layers46.

The adjuster86is coupled to the brace70and the shaft72. More specifically, the adjuster86is coupled to an end of the shaft72and disposed through the brace70. The adjuster86is threaded and includes a nut88cooperating with the threads of the adjuster86. As such, tightening or loosening the nut88causes the adjuster86to move the shaft72to a desired position which adjusts the roller78relative to the outer surface50of the mandrel44. In other words, threading the nut88on the adjuster86up or down causes the adjuster86to move the shaft72and correspondingly move the support(s)76. Movement of the shaft72and the support(s)76correspondingly moves the roller78relative to the outer surface50of the mandrel44. As such, the adjuster86allows the shaft72and thus the roller78to selectively tilt. In addition, the adjuster86allows the shaft72to rotate about the central axis C relative to the adjuster86. In other words, for example, when rotating the roller78to the upward position, the roller78, the support(s)76, and the shaft72rotate relative to the adjuster86. Hence, the adjuster86does not rotate about the central axis C. In one configuration, the adjuster86can be further defined as a tie rod rotatably attached to the shaft72. It is to be appreciated that bearings can be utilized for rotatably supporting the shaft72. It is to further be appreciated that the adjuster86can be any suitable configuration for adjusting the roller78complementary to the outer surface50of the mandrel44while also allowing the roller78to compensate for variances of the extrudate24. For example, as shown inFIG. 9, the adjuster86is shown schematically with the shaft72eliminated such that the support76is directly coupled to the roller78and the adjuster86.

As best shown inFIG. 12, the brace70defines an aperture90generally complementary to the adjuster86for removing the adjuster86from the brace70. Generally, the shaft72is removed from one side of the brace70and the adjuster86is removed from another side of the brace70. As such, the adjuster86is removed from the side of the brace90defining the aperture90. It is to be appreciated that in certain configurations, the adjuster86and the shaft72can both be removed from the brace70through the aperture90. It is to be appreciated that the adjuster86and the shaft72can be removed from the brace70by any suitable method.

A second substance can be applied to the extrudate24prior to or simultaneously with applying pressure to the extrudate24for assisting with the leveling of the extrudate24. It is to be appreciated that the second substance can also be of any suitable composition, including water, to increase adhesion. The second substance can be applied to the second side42of the layers46for assisting the pressure-applying device68to level the second side42of the layers46.

Referring back toFIG. 1, the manufacturing apparatus20can also include a plurality of second cutters92adjacent the mandrel44for trimming the extrudate24or the layers46as the extrudate24or the layers46are wrapped about the mandrel44. More specifically, the extrudate24includes a first outer edge94and a second outer edge96spaced from each other adjacent the first and second sides40,42with one of the second cutters92adjacent the first outer edge94and another one of the second cutters92adjacent the second outer edge96. One of the second cutters92trims or cuts the first outer edge94of the extrudate24and the other one of the second cutters92trims or cuts the second outer edge96of the extrudate24. The second cutters92can be rotated relative to the mandrel44for adjusting the position of the second cutters92. It is to be appreciated that the first and second outer edges94,96can be trimmed or cut by any suitable machine, device, apparatus, by hand, etc. For example, the second cutters92can be defined as a knife, etc. It is to be appreciated that the second cutters92as shown inFIG. 1are rotated out of engagement from the layers46for illustrative purposes only.

Turning toFIG. 10, the manufacturing apparatus20can also include a heating apparatus98, such as an oven or a kiln. The heating apparatus98is shown schematically and it is to be appreciated that the preform22can be heated by other methods, such as an open heat source. The heating apparatus98heats the preform22to a plurality of elevated temperatures. The preform22is placed in the heating apparatus98and heated to a second temperature. Generally, the preform22is disposed on the mandrel44during this heating to the second temperature. It is to be appreciated that the preform22can be heated to the second temperature by alternative methods. The second temperature is of from about 70 to 200 degrees Fahrenheit. Generally, heating is utilized for evaporating water, burning off any organic binder and filler from the preform22, and setting the inorganic binder to strengthen the preform22, which defines void space in the preform22. As shown, the mandrel44with the preform22, i.e., the mandrel44with the wrapped layers46of the extrudate24, is disposed in the oven as a single unit. It should be appreciated that heating the preform22can be accomplished through a variety of different methods.

Generally, the preform22is heated to the second temperature to dry the preform22. At this point, the preform22is known as an uncured ceramic article. The preform22is held at the second temperature until a gel point of the organic binder is reached which occurs after about 90 to 240 minutes. The preform22is then removed from the heating apparatus98and the mandrel44.

Once the preform22is removed from the mandrel44, the preform22is again placed into the heating apparatus98and again heated to the second temperature until the moisture content of the preform22is of from about 0 to 18 percent, and more specifically, of from about 5 to 10 percent.

The preform22is subsequently heated to a third temperature for about 30 to 90 minutes and more specifically for about 60 minutes for burning off the organic binders and the fillers within the composition. The third temperature is of from about 450 to 700 degrees Fahrenheit and more specifically of from about 475 to 525 degrees Fahrenheit.

The preform22is then heated to a fourth temperature for about 90 to 150 minutes and more specifically for about 105 to 135 minutes to set the inorganic binder and provide the preform22with excellent strength at high temperatures. The fourth temperature is of from about 1,600 to 2,000 degrees Fahrenheit and more specifically of from about 1,700 to 1,900 degrees Fahrenheit. After the step of heating the preform22to the fourth temperature, the preform22can be referred to as a cured or sintered ceramic article. After the preform22has been cured, the preform22can also be machined to a final configuration if desired.

FIG. 11illustrates the preform22removed from the mandrel44after being heated, etc. and the layers52,54,56secured to each other to further define the uniform thickness T. In other words, the dash-dot-dot-dash lines ofFIG. 11represent where the initially wrapped layers52,54,56were prior to curing the preform22. The configuration of the preform22, i.e., the wrapped layers46, allows the preform22to be removed from the mandrel44without being damaged. In other words, the preform22can be removed from the mandrel44without the layers46or the first and second ends36,38separating, and additional, can be removed from the mandrel44without cracking the preform22.

Referring toFIG. 12, the manufacturing apparatus20can be utilized to automate production of the preforms22. The mandrel44is further defined as a first mandrel44and the manufacturing apparatus20further includes a second mandrel100spaced from the first mandrel44. The second mandrel100includes the same components as described above for the first mandrel44, and therefore, the features of the second mandrel100will not be discussed further. As such, the outer surface50of the second mandrel100can be flat or tapered as discussed above.

The second mandrel100is supported by a second bracket102. A second pivot104is coupled to the second bracket102with a second motor106coupled to the second pivot104for rotating the second mandrel100. It is to be appreciated that the second mandrel100can be selectively secured to the second pivot104by another clamp49engaging one end of the second pivot104. The second pivot104and the clamp49cooperate for allowing the second mandrel100to be easily removable from the second pivot104and the second bracket102, thus automating production of the preforms22. The second motor106is coupled to the second pivot104for rotating the second mandrel100about the longitudinal axis L. The second motor106rotates the second pivot104which causes the second mandrel100to rotate about the longitudinal axis L. It is to be appreciated that the second motor106can be any suitable horsepower and configuration for rotating the second mandrel100.

A second pressure-applying device108is utilized with the second mandrel100. The second pressure-applying device108is a minor image of the pressure-applying device68discussed above, and therefore, the second pressure-applying device108includes the same components which will not be discussed further. As such, inFIG. 12, the pressure-applying device68for the first mandrel44is illustrated with the roller78engaging the outer surface50of the first mandrel44and the second pressure-applying device108for the second mandrel100is illustrated with the roller78in the upward position with the roller78prevented from engaging the preform22or the second mandrel100. It is to be appreciated that the second pressure-applying device108can be configured as illustrated in the embodiment ofFIG. 9.

The first and second mandrels44,100are spaced from each other such that the first mandrel44can be removed from the pivot47without interfering with the second mandrel100. Likewise, the second mandrel100can be removed from the second pivot104without interfering with the first mandrel44. As such, the first and second mandrels44,100are easily removable from the pivot47and the second pivot104respectively for automating production of the preforms22.

The manufacturing apparatus20further includes a platform110supporting the first and second mandrels44,100for automating production of the preforms22. Hence, the bracket48that supports the first mandrel44is attached to the platform110and the second bracket102that supports the second mandrel100is also attached to the platform110. Further, it is to be appreciated that the brace70that supports the pressure-applying device68can be attached to the platform110and another brace70that supports the second pressure-applying device108can be attached to the platform110.

The platform110is movable relative to the multi-screw extruder26such that the first and second mandrels44,100move relative to the multi-screw extruder26for wrapping the extrudate24about one of the first and second mandrels44,100while an other one of the first and second mandrels44,100is removable from the platform110. The platform110moves transverse to the first direction of the extrudate24. In other words, the platform110moves back and forth such that one of the first and second mandrels44,100align with the extrudate24exiting the die plate32of the multi-screw extruder26while the other one of the first and second mandrels44,100is offset from the extrudate24. For example, as shown inFIG. 12, the first mandrel44is aligned with the exiting end30of the multi-screw extruder26while the second mandrel100is offset from the exiting end30.

Once the preform22is wrapped about the first mandrel44and the second end38is cut, the preform22is ready for the next step in the process. Therefore, the platform110moves transverse to the first direction such that the second mandrel100aligns with the extrudate24to wrap the extrudate24about the second mandrel100to form another preform22. When the extrudate24is being wrapped about the second mandrel100, the preform22disposed on the first mandrel44can be removed and a third mandrel (not shown) can be coupled to the pivot47to form yet another preform22. Once the preform22is wrapped about the second mandrel100and the second end38is cut, this preform22is ready for the next step in the process. As such, the platform110again moves transverse to the first direction such that the third mandrel aligns with the extrudate24to wrap the extrudate24about the third mandrel to form yet another preform22. This process continues until the desired number of preforms22are formed. As such, the platform110automates production of the preforms22, thus more efficiently increasing output of the preforms22.

Turning toFIGS. 1-4, the present invention further provides a method of forming the preform22from the extrudate24having the first end36and the second end38utilizing the mandrel44. It is to be appreciated that the method as discussed herein can be accomplished by utilizing the manufacturing apparatus20as discussed above or by any other suitable apparatus. The composition is processed within the multi-screw extruder26with the composition extruded through the die plate32to form the extrudate24. Forming the extrudate24can be accomplished by utilizing the multi-screw extruder26and the die plate32as discussed above or any other suitable process.

The method includes the steps of forming the first end36of the extrudate24, wrapping the extrudate24about the mandrel44to form the first layer52having the first end36abutting the mandrel44, and applying pressure to the first layer52during wrapping of the extrudate24about the mandrel44. More specifically, the first end36of the extrudate24defines the first angle α relative to the first side40as discussed above and the step of forming the first end36is further defined as the step of cutting the first end36to the first angle α.

The method further includes the steps of forming the second end38of the extrudate24complementary in configuration to the first end36, wrapping the extrudate24about the mandrel44to form the second layer54on top of the first layer52with the second end38spaced from the mandrel44, and applying pressure to the second layer54during wrapping of the extrudate24about the mandrel44. More specifically, the second end38of the extrudate24defines the second angle β relative to the second side42as discussed above and the step of forming the second end38is further defined as the step of cutting the second end38to the second angle β.

Hence, the extrudate24is defined as the continuous piece of extrudate24between the first and second ends36,38as discussed above and the steps of wrapping the extrudate24about the mandrel44is further defined as the steps of wrapping the continuous piece of extrudate24about the mandrel44to form the first and second layers52,54.

The step of forming the first end36occurs before the step of forming the second end38and additionally, the step of forming the first end36occurs before the step of wrapping the extrudate24about the mandrel44to form the second layer54. Further, the step of forming the second end38occurs after the step of wrapping the extrudate24about the mandrel44to form the second layer54. In addition, the step of applying pressure to the first layer52occurs before the step of applying pressure to the second layer54.

The extrudate24includes the first side40and the second side42opposing the first side40such that the first and second layers52,54include the first and second sides40,42as discussed above. As such, the step of wrapping the extrudate24about the mandrel44to form the first layer52is further defined as abutting the first side40of the first layer52to the mandrel44. Further, the step of wrapping the extrudate24about the mandrel44to form the second layer54is further defined as abutting the first side40of the second layer54to the second side42of the first layer52.

In one embodiment, the method further includes the step of wrapping the extrudate24about the mandrel44to form the third layer56on top of the second layer54. As such, the extrudate24is defined as the continuous piece of extrudate24such that the steps of wrapping the extrudate24about the mandrel44is further defined as the steps of wrapping the continuous piece of extrudate24about the mandrel44to form the first52, second54, and third56layers. In this configuration, the step of forming the first end36occurs before the step of forming the second end38. In addition, the steps of applying pressure to the first and second layers52,54are further defined as the steps of applying pressure to the first52, second54, and third56layers during wrapping of the extrudate24about the mandrel44. Further, the step of applying pressure to the first layer52occurs before the steps of applying pressure to the second and third layers54,56. More specifically, the steps of applying pressure to the first and second layers52,54occur before the step of applying pressure to the third layer56.

The method also includes the step of aligning the second end38complementary to the first end36of the first layer52in the spaced relationship to define the preform22having the substantially uniform exterior surface60and the substantially uniform thickness T. In one embodiment, the second layer54has the second end38and the step of aligning the second end38complementary to the first end36of the first layer52in the spaced relationship is further defined as the step of aligning the second end38of the second layer54complementary to the first end36of the first layer52in the spaced relationship to define the preform22having the substantially uniform exterior surface60and the substantially uniform thickness T. In another embodiment, the third layer56has the second end38and the step of aligning the second end38complementary to the first end36of the first layer52in the spaced relationship is further defined as the step of aligning the second end38of the third layer56complementary to the first end36of the first layer52in the spaced relationship to define the preform22having the substantially uniform exterior surface60and the substantially uniform thickness T.

Further, the present invention also provides a method of forming the ceramic preform22comprising ceramic particles and ceramic fibers having an aspect ratio of greater than or equal to 10:1 and the ceramic fibers substantially randomly orientated in three dimensions utilizing the mandrel44and the extruder26as discussed above. This method is similar to the method discussed above and therefore can include the steps discussed above for the other method. Only a few of the steps for this other method are set forth below for illustrative purposes.

The method includes the step of extruding the ceramic particles and the ceramic fibers through the extruder26to form the extrudate24having the first end36and the second end38. The method further includes the steps of forming the first end36of the extrudate24, wrapping the extrudate24about the mandrel44to form the first layer52having the first end36abutting the mandrel44, and applying pressure to the first layer52during wrapping of the extrudate24about the mandrel44. In addition, the method includes the steps of forming the second end38of the extrudate24complementary in configuration to the first end36, wrapping the extrudate24about the mandrel44to form the second layer54on top of the first layer52with the second end38spaced from the mandrel44, and applying pressure to the second layer54during wrapping of the extrudate24about the mandrel44.

The method also includes the step of aligning the second end38complementary to the first end36of the first layer52in the spaced relationship to define the preform22having the substantially uniform exterior surface60and the substantially uniform thickness T. In one embodiment, the method further includes the step of wrapping the extrudate24about the mandrel44to form the third layer56on top of the second layer54. As such, the extrudate24is defined as the continuous piece of extrudate24between the first and second ends36,38such that the steps of wrapping the extrudate24about the mandrel44is further defined as the steps of wrapping the continuous piece of extrudate24about the mandrel44to form the first52, second54, and third56layers. Therefore, the third layer56has the second end38and the step of aligning the second end38complementary to the first end36of the first layer52in the spaced relationship is further defined as the step of aligning the second end38of the third layer56complementary to the first end36of the first layer52in the spaced relationship to define the preform22having the substantially uniform exterior surface60and the substantially uniform thickness T.

It is to be appreciated that the methods as discussed above can include various additional steps. For example, the methods can further include the steps of cooling the mandrel44and/or heating the preform22to one or more temperatures, as discussed above, etc.

VARIOUS ADDITIONAL EMBODIMENTS

It is contemplated that after the preform22is formed according to the instant invention, the preform22may be heated, fired, and/or sintered at any temperature as selected by one of skill in the art. After heating, the preform22may be described as the ceramic article. In one embodiment, the ceramic article includes the firing (or sintering) product of ceramic particles, ceramic fibers having an aspect ratio of greater than or equal to 10:1, an organic binder comprising a cellulose ether, an inorganic binder comprising silica; and water. It is contemplated that greater than 90 out of 100 ceramic fibers may be randomly oriented in three dimensions in the ceramic article. Additionally, greater than 85 parts by volume of the ceramic fibers may be uniformly distributed in the ceramic article on a scale of twice the diameter of the ceramic fibers. Further, the ceramic article may have a consistent density of from 0.9 to 1.1 g/cm3in x-, y-, and z-dimensions and/or have a uniform strength in three dimensions as measured in accordance with ASTM C1424. In another embodiment, the ceramic fibers are present in the ceramic article in an amount of from 3 to 15 parts by volume based on 100 parts by volume of the ceramic article. In still another embodiment, the ceramic fibers comprise an element from period 2, 3, 4, or 5 of the periodic table of the elements, such as aluminum, silicon, oxygen, zirconium, or carbon. It is also contemplated that the ceramic fibers may be selected from the group of alumina-silica fibers, alumina-silica-zirconia fibers, carbon-graphite fibers, and combinations thereof. In still another embodiment, the ceramic particles are present in the ceramic article in an amount of from 15 to 30 parts by volume based on 100 parts by volume of the ceramic article. Alternatively, the ceramic particles may include an element from period 2, 3, or 4 of the periodic table of the elements such as silicon, oxygen, carbon, aluminum, or boron. Alternatively, the ceramic particles may be selected from the group of silicon carbide, alumina, boron carbide, and combinations thereof. In one embodiment, the ceramic article is as described in U.S. patent application Ser. No. 12/174,982, which is expressly incorporated herein by reference.

Many modifications and variations of the present invention are possible in light of the above teachings. The foregoing invention has been described in accordance with the relevant legal standards; thus, the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment can become apparent to those skilled in the art and do come within the scope of the invention. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.