CA2185034A1 - Molding material under the application of shear, compressive and/or tensile loads - Google Patents
Molding material under the application of shear, compressive and/or tensile loadsInfo
- Publication number
- CA2185034A1 CA2185034A1 CA002185034A CA2185034A CA2185034A1 CA 2185034 A1 CA2185034 A1 CA 2185034A1 CA 002185034 A CA002185034 A CA 002185034A CA 2185034 A CA2185034 A CA 2185034A CA 2185034 A1 CA2185034 A1 CA 2185034A1
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- Canada
- Prior art keywords
- moldable material
- flow
- mandrel
- mold
- molding apparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
An apparatus and system for molding a flow of moldable material under the application of shear, compressive and/or tensile loads. The apparatus includes a mold housing that has a flow of moldable material supplied to it.
First and second boundary elements, located within the mold housing, define the first and second side of the flow of moldable material. A driver in contact withthe first boundary element deflects the first boundary element in a direction substantially perpendicular to the flow of the moldable material. The deflectionof the first boundary element imposes shear, compressive and tensile loads on the flow. The applied shear, compressive and tensile loads produce mixing of the moldable flow of material and can also be controlled to effect the rheological properties of the moldable material. A flexible joint is incorporated into the apparatus to allow the first boundary element to deflect. A system is also disclosed which includes the steps of mixing a first material component anda second material component so as to produce a mixture. The mixture is melted to form a moldable material. The moldable material is conveyed between first and second boundary elements of the molding apparatus. A portion of the first boundary element is deflected in a direction substantially perpendicular to the flow of moldable material. The deflection of the first boundary element imposes shear, compressive and tensile loads on the flow of moldable material.
The moldable material is then cured into a final product.
First and second boundary elements, located within the mold housing, define the first and second side of the flow of moldable material. A driver in contact withthe first boundary element deflects the first boundary element in a direction substantially perpendicular to the flow of the moldable material. The deflectionof the first boundary element imposes shear, compressive and tensile loads on the flow. The applied shear, compressive and tensile loads produce mixing of the moldable flow of material and can also be controlled to effect the rheological properties of the moldable material. A flexible joint is incorporated into the apparatus to allow the first boundary element to deflect. A system is also disclosed which includes the steps of mixing a first material component anda second material component so as to produce a mixture. The mixture is melted to form a moldable material. The moldable material is conveyed between first and second boundary elements of the molding apparatus. A portion of the first boundary element is deflected in a direction substantially perpendicular to the flow of moldable material. The deflection of the first boundary element imposes shear, compressive and tensile loads on the flow of moldable material.
The moldable material is then cured into a final product.
Description
\57596
2!18~o3 MOLDING MATERIAL UNDER THE APPLICATION OF SHEAR, COMPRESSIVE AND/OR TENSILE LOADS
Field of the Invention The present invention relates to apparatus for molding moldable material while applying compressive and shear loads to a flow of the material 15 for transforming the material. More particularly, the apparatus and system use an eccentric drive for creating and applying the compressive and shear loads.
Background of the Invention The processing of deformable materials generally involves the 20 transformation of a starting material (i.e., in a solid state or a liquid state), which is in a fungible form (e.g., powder, beads, granules, pellets, etc.), intoa final or intermediate product having a specific shape, dimensions and properties. Processes useful in the transformation of moldable materials from their initial fungible form to the form of the final or intermediate product are25 well known to those skilled in the materials processing industry. For instance, if the moldable material is a plastic, examples of plastic transformation processes include extrusion, transfer molding, calendaring, l~min~ting, thermoforming, injection molding, compression molding, blow molding, and the like. As used herein, such transformation processes and/or operations are 30 collectively referred to as "molding" processes. Similarly, the resulting final . \17596 2 18~3q or intermediate product is referred to as "molded," regardless of the specific transformation process employed in its m:~nl-f~cture.
In order to produce molded products having a specific geometric configuration, it is generally necessary to employ a mold or die. The primary 5 objective of a mold or die is to shape moldable material introduced therein byconfining the material to a preselected shape and rel~ining the material in thatconfined state until it cures.
The physical properties of a molded product depend, in part, upon the specific molding process conditions and steps employed. It has been 10 observed that dirr~le~lL molding processes will often result in the final or intermediate products having different physical properties. For example, the amount of shear stress applied to the material during molding determines, in part, the degree of molecular orientation and crystallization (in crystallizablematerials) within the molded product. This, in turn, has an effect on the 15 molded product's physical properties, such as yield strength.
One method of controlling the amount of shear stress applied during molding of a molded product (and thereby controlling some of the product's physical properties), is commonly referred to as "flow technology. "
The concept of "flow technology, " as it relates to plastic molding processes, is 20 concerned with the behavior of a moldable plastic material before, while, andafter it is introduced into a mold and/or being passed through a die. It has been discovered that the properties of a final or intermediate molded product depend largely upon how the moldable material flows prior to, and/or while, being subjected to a molding process. For example, two products having identical 25 dimensions and made from the same basic starting material, but which are molded under different conditions (e.g., different hydrostatic pressures and/or shear stresses) and subjected to different flow patterns, will have different physical properties.
This phenomenon is due, in part, to the fact that, as a moldable 30 material flows prior to, or while, entering a mold or passing through a die, it \57596
Field of the Invention The present invention relates to apparatus for molding moldable material while applying compressive and shear loads to a flow of the material 15 for transforming the material. More particularly, the apparatus and system use an eccentric drive for creating and applying the compressive and shear loads.
Background of the Invention The processing of deformable materials generally involves the 20 transformation of a starting material (i.e., in a solid state or a liquid state), which is in a fungible form (e.g., powder, beads, granules, pellets, etc.), intoa final or intermediate product having a specific shape, dimensions and properties. Processes useful in the transformation of moldable materials from their initial fungible form to the form of the final or intermediate product are25 well known to those skilled in the materials processing industry. For instance, if the moldable material is a plastic, examples of plastic transformation processes include extrusion, transfer molding, calendaring, l~min~ting, thermoforming, injection molding, compression molding, blow molding, and the like. As used herein, such transformation processes and/or operations are 30 collectively referred to as "molding" processes. Similarly, the resulting final . \17596 2 18~3q or intermediate product is referred to as "molded," regardless of the specific transformation process employed in its m:~nl-f~cture.
In order to produce molded products having a specific geometric configuration, it is generally necessary to employ a mold or die. The primary 5 objective of a mold or die is to shape moldable material introduced therein byconfining the material to a preselected shape and rel~ining the material in thatconfined state until it cures.
The physical properties of a molded product depend, in part, upon the specific molding process conditions and steps employed. It has been 10 observed that dirr~le~lL molding processes will often result in the final or intermediate products having different physical properties. For example, the amount of shear stress applied to the material during molding determines, in part, the degree of molecular orientation and crystallization (in crystallizablematerials) within the molded product. This, in turn, has an effect on the 15 molded product's physical properties, such as yield strength.
One method of controlling the amount of shear stress applied during molding of a molded product (and thereby controlling some of the product's physical properties), is commonly referred to as "flow technology. "
The concept of "flow technology, " as it relates to plastic molding processes, is 20 concerned with the behavior of a moldable plastic material before, while, andafter it is introduced into a mold and/or being passed through a die. It has been discovered that the properties of a final or intermediate molded product depend largely upon how the moldable material flows prior to, and/or while, being subjected to a molding process. For example, two products having identical 25 dimensions and made from the same basic starting material, but which are molded under different conditions (e.g., different hydrostatic pressures and/or shear stresses) and subjected to different flow patterns, will have different physical properties.
This phenomenon is due, in part, to the fact that, as a moldable 30 material flows prior to, or while, entering a mold or passing through a die, it \57596
- 3 -is subjected to a shear stress, which is commonly referred to as "flow shear stress." Flow shear stress induces molecular orientation in the plastic material(i.e., it results in the macromolecules in the material ~ligning themselves in the direction of flow). The flow shear stress varies from a maximum level at the outside surface of the flowing moldable material to a minimum level at the center, where the material is slowest to cure.
A problem with existing molding processes is the inability to simply and inexpensively provide thorough mixing of two constituent parts of a moldable material. For example, the moldable material may consist of a base polystyrene component material and a coloring agent. Alternately, the constituent components could be a base resin or matrix material and an additive or curing agent which, when mixed, form a moldable material as in a thermoset material. A variety of other examples of moldable materials exist which consist of two or more combined components and which must be mixed to form the final product. In the prior art processes, mixing of the two components was typically achieved either in a hopper or while conveyed by designated processing machinery. In either case, it is important that the mixing be thorough in order to achieve a structurally or cosmetically acceptable final product. The uniformity in color of a final molded product is extremely important in today's commercial marketplace. Since many products are ultimately selected by a consumer based on their appearance, m:~mlf~cturers strive to distinguish their products through specific coloring. The inefficient manufacturing processes discussed above are perceived as drawbacks by these manufacturers for generating the desired coloring.
Another problem with the prior art processes occurs when only a small amount of one constituent is to be mixed with a large amount of a second constituent. In this situation, the utilization of only the hopper to mixthe two constituents may not result in a homogeneous mixture. For example, only one or two color pellets are typically needed to sufficiently color one pound of uncolored polystyrene pellets. However, simply mixing one or two \57596 2 ~ 8SQ~9 unmelted colored pellets into thousands of unmelted uncolored polystyrene pellets and then melting the mixture will not provide an even color distributionin the final product.
The prior art processes are also inefficient when it is desirable to combine dissimilar components which do not readily and easily mix with one another. In order to produce the desired mixing, the prior art processes mix thematerials for an extended period of time or subject the materials to additional m~mlf~cturing steps.
The screw in an extruder is generally used to provide additional mixing of the constituent parts. The flights on the screw, acting in conjunctionwith walls of the extruder barrel, produce a rolling or kn~a(ling of the moldable material as it is melted, compressed and driven toward the exit of the extruder.If a single screw does not provide sufficient mixing, multiple intermeshing screws are utilized. The intermeshing of the screw flights more thoroughly kneads the constituent parts of the material into a single homogeneous mixture.
A drawback to the use of multiple screws is the need for a complicated drive mechanism for rotating the multiple screws. Furthermore, the multiple screws produce excessive heat and compression of the moldable material, resulting in degradation of the material.
In order to compensate for the inefficient mixing that occurs with the prior art processes, excessive amounts of one or more component part of the moldable material are sometimes added. For example, as discussed above, one or two coloring agent pellets would, under proper mixing conditions, be sufficient to color a pound of uncolored polystyrene pellets. However, since most mixing systems do not adequately mix the component materials, it is typically required that more coloring pellets be used per pound of uncolored polystyrene. This increases the cost of manufacturing the final colored product.Another problem in the prior art relates to mixing of recyclable materials. There is a trend to increase the amount of recyclable material 30 incorporated into a final molded part. In many instances, the recyclable \57596 ~8s~3q material must be combined with virgin material prior to solidification. If the recycled material is not adequately mixed with the virgin material, flaws or we~kn~sses can develop in the final product.
The prior art devices are also deficient when it is desired to mix 5 multicomponent systems with more than one polymer component (e.g., rubber or plastic) and/or more than one additive. For example, prior art devices do notefficiently mix filler material, such as reinforcing materials or plasticizers, which are used to improve one or more of the properties of the final product.
Prior art devices incorporate dry reiforcing fibers into the material either in the 10 hopper or while in the extruder barrel. Neither method provides an effective method for reiforcing the material. On the contrary, mixing the fibers with the molten material prior to or during conveyance in the extruder causes fiber breakage and excessive extruder wear. To minimi7e the damage to the extruder, prior art devices incorporate the fibers near the end of the screw.
15 However, this results in poor mixing of the plies into the melt and still results in wear of the last few flights of the extruder screw.
A need therefore exists for an appa~ s and system which facilitates the mixing and transformation of a moldable material prior to and/orduring solidification. Furthermore, a need exists for a system for reinforcing 20 a moldable material flow without causing excessive wear of the extruder screw.
Sumrnary of the Invention The present invention relates to an al~par~lus and a system for subjecting a flow of moldable material to shear, compressive 25 and/or tensile loads.
In another aspect the present invention provides an app~lus and system for thoroughly mixing a flow of moldable material.
- In yet another aspect the present invention provides an apparatus and system for displacing a flow of moldable material so as to 30 produce mixing of the material.
~- \S7596 ~1 ~5~34 These and other aspects and advantages of the present invention are achieved by the novel apparatus and system for molding a flow of moldable material under the application of shear, compressive and/or tensile loads. The apparatus comprises a mold housing that has a flow of moldable material S supplied to it. A first boundary element is located within the mold housing and defines a first side of the flow of moldable material. A second boundary element also positioned within the mold housing defines a second side of the flow of moldable material. A driver in driving contact with the first boundary element is adapted to produce a deflection of the first boundary element in a 10 direction subst~nti~lly perpendicular to the flow of the moldable material. The deflection of the first boundary element imposes shear, compressive and tensile loads on the flow which function to transform the moldable material. In one embodiment of the invention, the applied shear, compressive and tensile loads produce mixing of the moldable flow of material. In another embodiment of the 15 invention, the shear, compressive and tensile loads are controlled for effecting the rheological properties of the moldable material prior to and during curing.
The imposed forces also function to increase the mixing of the moldable flow without the need for further mixing devices.
A flexible joint is incorporated into the apparatus to allow the 20 first boundary element to deflect. In one embodiment of the invention, the flexible joint is configured as a cylindrical wave or bellows. This cylindrical wave attaches to the first boundary element or mandrel which may also be cylindrical in shape.
In one configuration, the driver comprises an eccentric portion 25 of a drive shaft. The rotation of the drive shaft causes the eccentric portion to rotate eccentric to the shaft's axis of rotation. This eccentric rotation causes the deflection of the first boundary element. The amount of deflection may be varied as desired by means of a bearing assembly which includes a rotatable eccentric bearing journal.
85l75965 2 ~ ~03~
A system for transforming a flow of moldable material is also disclosed. The system includes the steps of mixing a first material component and a second material component so as to produce a mixture. The mixture is then melted to form a moldable material. The moldable material is conveyed 5 between a first and second boundary element of a molding apparatus. A portion of the first boundary element is deflected in a direction substantially perpendicular to the flow of moldable material. The deflection of the first boundary element imposes shear, compressive and tensile loads on the flow of moldable material which produce further mixing of the moldable material. The 10 moldable material is then cured into a final product.
The novel apparatus and system result in moldable material which is more thoroughly and efflciently mixed than has heretofore been possible by prior art processes. The novel apparatus and system also controls the rheological properties of the moldable material for reducing the residual stress15 and/or elimin~ting the melt fracture in the final product.
The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof, as illustrated in the accompanying figures.
Brief Description of the Dldwi~
For the purpose of illustrating the invention, the drawings show a form of the invention which is presently preferred. However, it should be understood that this invention is not limited to the precise arrangements and 25 instrumentalities shown in the drawings.
Figure 1 illustrates the present invention as it is utilized in a die molding system.
Figure 2 is a section view of an extruder used to feed a moldable material into a die housing.
\57596 2 1 ~5~34 Figure 3 is a schematic representation of a prior art molding apparatus.
Figures 4A-4D are schematic representations of a molding apparatus made according to the present invention for use in applying shear and 5 colllplessive loads to a flow of moldable material.
Figure 5 is a detail view of one arrangement of the driver for use in deflecting or eccentrically offsetting a mold surface.
Figure 6 is a section view of the molding apparatus taken along lines 6-6 in Figure S.
Figure 7 is a side view of the molding apparatus taken along lines 7-7 in Figure 5.
Figure 8 is a detail view of one arrangement of the flexible joint for accommodating the deflection of the mandrel.
Figure 9 is a illustration of a test sample produced according to a prior art method.
Figures lOA and lOB illustrate two test samples produced according to one embodiment of the present invention.
Figure 11 illustrates an embodiment of the present invention as it is utilized in a blow molding system.
Figure 12 illustrates an embodiment of the present invention wherein the extruder and the drive shaft are formed as an integral unit.
Figure 13 illustrates an embodiment of the present invention as it is utilized in fabricating flat die molded sheets of material.
Figure 14 illustrates a section view of the flat die molded sheet embodiment of the present invention.
Figures l5A and l5B illustrate two eccentric positions of the driver for use in deflecting or eccentrically offsetting a mold surface.
Figure 16 illustrates an embodiment of the present invention for use in m~mlf~cturing a molded product made with fiber reinforced molded material.
` \57596 ~ g3 Figure 17 illustrates another embodiment of the present invention for use in m~nllfacturing a molded product made with fiber reinforced molded material.
Figure 18 illustrates an embodiment of the present invention S wherein the mandrel is eccentric with respect to the die mold.
Detailed Des~ Jtion of the Preferred Embodillle--ls Referring now to the drawings, wherein like reference numerals illustrate corresponding or similar elements throughout the several views, Figure 10 1 illustrates one embodiment of the present invention as it is incorporated in a die molding assembly 10. The die molding assembly 10 includes an extruder 12, a mold housing 14, and one or more mold dies 16. A power unit 18 is used to rotate an internally mounted drive shaft 20 which will be discussed in more detail below.
The extruder 12 is illustrated in more detail in Figure 2. The extruder 12 generally includes a hopper 22 for supplying a preferably unmelted, fungible moldable material into a extruder housing or barrel 24. A screw 26 is located within the extruder barrel 24 and is rotated by a motor drive 27. Thescrew 26 contains one or more flights 26' which, when the screw is rotated, 20 drive or feed the moldable material from the hopper 22 to an extruder port 28in the extruder barrel 24. The screw 26 also functions to melt, compress and homogenize the moldable material during translation from the hopper 22 to the port 28. At least one heater 30 is located on or adjacent to the extruder barrel24. The heater 30 transmits heat to the moldable material causing it to melt as 25 it is translated by the screw 26 to the port 28.
In one plerelled embodiment, the extruder port 28 directs the flow of moldable material from the extruder 12 into the mold housing 14. A
flow divider (not shown) channels the incoming flow of moldable material into the mold dies 16 which define the external shape or boundary of the final 30 product. In the embodiment illustrated, the mold dies 16 define the external \57596 ~ 1 85~3~
surface of a cylindrical tube. A mandrel 32 is located within the die molds 16 and forms an internal mold boundary along which the moldable material flows.
Hence, in this embodiment, the moldable material flows or is channeled between the inner surface of the outer mold dies 16 and the outer surface of theS inner mandrel 32 which define the final product shape. In the illustrated embodiment, the final product shape is a tube or cylinder such as a pipe.
Alternate shapes may also be practiced within the scope of the invention.
As discussed above, the screw 26 compresses and conveys the moldable material while in the extruder 12. The moldable material is fed into the mold housing and is forced to flow between the mold dies 16 and the mandrel 32 by pressure from the continuous rotation of the screw 26. Hence, the speed of the screw 26 determines the speed that the final product is output from the die molding assembly 10.
A series of temperature control units (not shown) may be positioned on or adjacent to the outer surface of the die molds 16. Both coolingand heating of the moldable material can be applied through the temperature control units. Those skilled in the art would readily be able to determine whether to cool or heat the material depending on the specific material being processed and/or the objectives sought. For example, cooling can be applied to shorten the solidification or curing time of the moldable material. Although the mold dies 16 are depicted as being relatively long in length, it should be appreciated that the desired length will depend at least on the amount of cooling required to solidify or cure the final molded product, and on the final product shape.
In order to more thoroughly mix the component parts of the moldable material, the present invention subjects the flow of moldable material to a load or deflection which is substantially perpendicular to the direction ofmaterial flow so as to impose compressive and shear loads on the flow.
Referring to Figure 1, in one embodiment of the invention, the material flowing between the mandrel 32 and the mold die 16is subjected to force caused by the \57596 as~34 eccentric rotation of a portion of the internal drive shaft 20. That is, a portion of the internal drive shaft 20 is eccentric to and in driving contact with the mandrel 32 so as to function as an eccentric driver. The eccentric driver produces an eccentric motion or deflection of the mandrel 32 with respect to thelongitudinal axis of rotation of the shaft so as to result in relative motion between the mandrel 32 and the die mold 16. This motion or deflection of the mandrel 32 is substantially perpendicular to the axial direction of the flow of moldable material between the mandrel 32 and the mold die 16. The deflection of the mandrel 32, in turn, subjects the flow of moldable material to shear, compressive, and tensile forces which result in further mixing of the moldable material just prior to and during solidification.
A better underst~n(ling of this eccentric motion can be had by reference to Figures 3 and 4A-4D. Figure 3 illustrates a section view of a priorart die mold system during operation. The mandrel 32 is concentric with the mold die 16. There is no internally mounted drive shaft since the prior art die molding assemblies typically do not apply rotational motion to the mandrel or the mold dies. As a consequence, there are no forces applied to the flow of moldable material (designated by numeral 34) by eccentric rotation of a drive shaft.
Referring to Figures 4A-4D, one embodiment of the present invention is shown wherein the drive shaft exerts an eccentric motion on the mandrel 32. Figures 4A-4D show the rotation of the drive shaft in 90 degree increments. In the embodiment illustrated, a portion 20' of the internal drive shaft 20 rotates eccentric to the shaft's longitudinal axis of rotation (designated by numeral 36 and shown in Figure 1). The eccentricity, 'e', is shown in Figure 1. As the eccentric portion 20' rotates, it deflects the mandrel 32 causing the mandrel 32 to move toward and away from the die mold 16. This motion produces compression, tension and shear forces in at least a portion of the moldable material flow 34. These applied compression, tension and shear \57596 ~18~
forces produce, as one consequence, an omni-directional mixing of the moldable material.
The applied compression, tension and shear forces also produce changes in the rheological properties of the molten material. That is, the S eccentricity of the drive shaft 20 with respect to the mandrel 32 can be tailored to produce compression and shear forces in the moldable material which, for example, alter the orientation and/or the flexural and tensile strength of the material. Transforming the physical characteristics of a moldable material is well known and is described in detail in U.S. Pat. Nos. 4,469,649 and 5,306,129 which are both incorporated herein by reference. The disclosed embodiments provide a novel means for achieving the change in the rheological properties of the material. It is contemplated that a controller may be utilizedto control the eccentric driving to produce the desired rheological properties.
Those skilled in the art would readily be capable of l]tili7ing the teaching of the 15 present invention for altering the rheological properties of the moldable material and, therefore, no further discussion is needed.
It is also well known that, during the flow process, molten polymers store a significant amount of elastic energy when subjected to pressure, such as from the screw of an extruder. This stored elastic energy in 20 the polymer melt could cause a high level of residual stress, die swell and/or melt fracture in the final molded article. The application of the compressive, tensile and shear loads on the molten polymer prior to and/or during solidification or curing can be used to control the level of elastic "memory" byinducing relaxation of the polymer molecules. This would result in the control 25 of the residual stress and/or elimin~tion of the melt fracture in the final molded part. Prior art methods of reducing the residual stress or melt fracture stress included reducing the applied pressure, increasing molding cycle time, ~nn~ling the molded article after it is already molded, etc. The present invention elimin~tes or reduces the need for such expensive and time-consuming 30 m~m-f~blring solutions.
\57596 ~ 1 35~3q As stated above, in one embodiment of the invention, a portion of the drive shaft 20 is formed eccentric to the longitll~lin~l axis of rotation 36 of the shaft. This embodiment is shown in Figures 1 and 5. As illustrated in Figure 5 and discussed above, the eccentric portion 20' of the drive shaft has a centerline 38 that is eccentric to the axis of rotation 36 of the shaft 20.
The eccentric portion 20' of the shaft is engaged with the mandrel 32 by means of a bearing assembly 40. The bearing assembly 40 includes a bearing journal 42 which has an inner surface 44 disposed around an outer surface 46 of the eccentric portion 20'. The bearing journal 42 also has an outer surface 48 which is in contact with an inner race 50 of a bearing 52.
Generally a tight fit is desired between the bearing journal 42 and the inner race 50 of the bearing 52 such that rotation of the bearing journal 42 produces rotation of the inner race 50. The bearing 52 also has an outer race 54 which is located between the inner race 50 and an inner wall or surface 56 of the mandrel 32. Preferably the outer race 54 is fit snug against the inner wall 56 of the mandrel 32 so as to prohibit or minimi7e motion therebetween.
Alternately, a second bearing journal (not shown) could be located between the outer race 54 and the mandrel 32 to minimi7e the size of the bearing needed.
The bearing assembly 40 permits the drive shaft 20 and eccentric portion 20' to rotate with respect to the mandrel 32 while m~int~ining engagement between the eccentric portion 20' and the mandrel 32.
In the illustrated embodiment, it is desirable that the bearing journal 42 rotate with the drive shaft 20. To achieve this, the bearing journal 42 may be directly locked into engagement with the drive shaft 20 and/or the eccentric portion 20' by means of a screw or pin 58 (shown in Figure 6).
Alternately and more preferably, a locking mechanism 60 may be utilized to attach the bearing journal 42 to the eccentric portion 20'. Referring to Figures5 and 7, the locking mechanism 60 is positioned adjacent to the bearing journal 42 and is disposed around the eccentric portion 20' of the shaft. The locking mechanism 60 is attached to the bearing journal 42 by means of the pin 58.
\SîS96 2 1 ~34 The locking mechanism 60 furthermore has a slot 62 formed therein, the width of which can be adjusted by a locking screw 64. Tightening of the locking screw 64 causes the width of the slot 62 to decrease. This, in turn, causes the locking mechanism to tighten around the eccentric portion 20 ' of the drive shaft.
5 As a result, rotation of the drive shaft 20 produces corresponding rotation of the bearing journal 42 and the inner race 50 of the bearing.
Alternate methods for eng~ging the eccentric portion 20' with the mandrel 32 are also within the purview of this invention. For example, the inner race 50 of the bearing 52 could be disposed directly on the outer surface 46 of the eccentric portion 20' elimin~ting the need for a bearing journal 42.
Furthermore, in an alternate arrangement, the locking mechanism 60 may be formed integral with the bearing journal 42 or, instead, the bearing journal could be attached to the eccentric portion 20' through a splined, keyed or similar type arrangement. In still yet another embodiment, a cam arrangement 15 similar to the one shown in Figures 4A-4D may be incorporated into the invention for functioning as the eccentric driver to produce the offset of the mandrel 32. It is also contemplated that the drive shaft can be formed without an eccentric portion 20'. Instead, the eccentric driver for producing the offsetof the mandrel is attached directly to the mandrel 32 itself. For example, the 20 bearing 52 can be mounted to the mandrel 32 in a non-concentric manner.
Normal rotation of the drive shaft 20 would result in the eccentric motion of the mandrel 32.
In one embodiment of the die molding assembly, the eccentricity e of the shaft 20 is preset and non-adjustable. In this embodiment, the bearing 25 journal 42 is shaped such that its outer surface 48 is concentric with the outer surface 46 of the eccentric portion 20'. As a result, the mandrel 32 will alwaysbe eccentrically driven by the drive shaft 20.
In a second, and more preferable, embodiment the amount of eccentricity e produced by the driver is adjustable depending on the amount and 30 type of loading desired on the moldable material. For example, in one \57596 ~ 1Q34j configuration, the eccentricity is adjustable from about zero inches to more than 0.125 inches. The amount of adjustability will, of course, differ depending on the configuration of the molding process and the shape of the resulting product.In order to achieve this variability in eccentricity, the outer surface 48 of the 5 bearing journal 42 has a shape which is not concentric with the outer surface 46 of the eccentric portion 20'. This bearing journal configuration is illustrated in Figures 5 and 6. It should be apparent that rotation of the bearing journal 42 with respect to the eccentric portion 20' will alter the amount that the mandrelis displaced or eccentrically offset. The combination of the bearing journal 42 and the eccentric portion 20' define a driver centerline 300. The amount of deflection of the mandrel 32 is a function of the distance between the driver centerline 300 and the longitudinal axis of rotation 36 of the shaft 20. Figure 15A illustrates one position of the bearing journal 42 and eccentric portion 20'combination. In this position, the driver centerline 300 lies substantially in line 15 with the longitlldin~l axis of rotation 36 of the shaft 20. Accordingly, there is substantially no eccentric offset of the mandrel 32 by the eccentric driver.
Figure 15B illustrates the bearing journal rotated into a second position. In this position, the driver centerline 300 is spaced apart from the longitudinal axis of rotation 36 of the shaft 20 by an eccentric distance e. Accordingly, the 20 eccentric offset of the mandrel 32 will be a function of this eccentricity e.Varying the eccentricity e, produces varying compression, tension and shear loads on the flow of moldable material.
In order to rotate the bearing journal 42 with respect to the eccentric portion 20', the locking mechanism 60 has flat surfaces 66 formed on 25 it to permit grasping of the locking mechanism 60 by a wrench or similar typeimplement. The drive shaft 20 is held in place while the locking mechanism 60 and the bearing journal 42 are rotated to produce the desired eccentricity e.
In the alternate splined or keyed arrangement discussed above, the bearing journal 42 is engaged with the proper splines or keys on the 30 eccentric portion 20' so as to provide the desired eccentricity e. In the alternate \57596 ~ I ~S~ ~4-embodiment discussed above where the bearing journal 42 is pinned directly into the drive shaft 20, multiple pin holes could be formed in the drive shaft in a circumferential pattern, each hole representing a different eccentric position.
Accordingly, the bearing journal would be pinned into the appropriate hole to 5 provide the desired eccentricity. It is also contemplated that the eccentric portion 20' of the shaft be removable such that portions with different eccentricities may be substituted as needed. Alternately, a portion of the mandrel 32 itself could be formed non-concentric with the die mold 16. Motion of the mold (e.g., rotational or lateral) would result in compression and shear 10 loads being applied to the moldable material flow. Those skilled in the art would readily appreciate the various alternate methods of adjusting the eccentricity that can be practiced within the scope of this invention. For example, a motor drive (not shown) could be mounted within the mandrel 32 for permitting automated adjustment of the eccentricity e.
As discussed above, rotation of the drive shaft 20 causes the eccentric portion 20' to produce a deflection or eccentric offset of the mandrel32. In the embodiment illustrated in Figure 1, the eccentric offset of the mandrel 32 occurs at a location apart from the point where the mandrel 32 attaches to the mold housing 14 and where the extruder 12 feeds the moldable 20 material into the mold housing 14. In order to permit the mandrel 32 to be displaced, the end of the mandrel 32 closest to the point where the moldable material enters the mold housing 14 is attached to the mold housing 14 through a flexible joint 68. The flexible joint 68 permits the mandrel 32 to remain relatively straight. Tn~te~(l, the offset or displacement of the mandrel 32 is 25 accommodated by angular flexure of the flexible joint 68. The flexible joint 68 preferably also biases the mandrel back to its undeflected position.
The incorporation of the flexible joint 68 reduces or elimin~tes the stresses which would otherwise develop in the mandrel 32 from the eccentric offset or deflection. Additionally, the angular flexure of the flexible joint and 30 resulting angular orientation of the mandrel 32 subject the flow of moldable \57596 ~ 1 85b34 material to an additional axial shear force which acts along substantially the entire longitl-~lin~l length of the mandrel 32. This added shear force helps to mix the moldable material and reduce the slip-stick behavior of the flow.
In one preferred embodiment, the flexible joint 68 comprises an internal wave 70 similar to a bellows. This type of configuration permits the internal wave 70 to flex radially in all directions. The bellows shape also allows the moldable material to flow relatively unobstructed through the mold housing 14 and onto the mandrel 32. During a standard molding process, pressures of up to 10,000 psi can be generated as the extruder 12 forces the moldable material into the mold housing 14. Accordingly, the internal wave 70 must be designed to with~t~nfl this applied pressure while also permitting the required angular flexure produced by the displacement of the mandrel 32. In the preferred embodiment, the internal wave 70 is made from 17-4PH stainless steel with a thickness of about 0.125 inches. A variety of other configurations and materials may be substituted for the preferred embodiment. For example, the wave could instead be constructed from fiber reinforced composite matrix material.
Referring to Figures 1 and 8, the internal wave 70 is attached to the mandrel 32 preferably through a threaded arrangement designated by the numeral 72. Alternate methods for attaching the mandrel 32 to the internal wave 70 can be utilized in the present invention. However, the selected method of attaching the mandrel 32 to the internal wave 70 should be designed to prevent or minimi7~ leakage of the moldable material into the interior of the mandrel 32 and onto the drive shaft 20 and its associated bearings.
The internal wave 70 is preferably attached to the mold housing 14 by means of a spindle 74. The spindle 74 is positioned within the flow divider (not shown) and can be threadingly engaged with the internal wave 70 or, as shown in the figure, can attach the internal wave 70 to the mold housing through a thrust type arrangement. Axial adjustment of the spindle 74 pulls the internal wave 70 toward the mold housing 14. Bearings 76 are located between \57596 - ~ ~ 35~34 the spindle 74 and the drive shaft 20 so as to permit the shaft 20 to rotate within the spindle 74.
Alternately, the flexible joint 68 may comprise a universal joint arrangement (not shown). The universal joi~t accommodates the angular 5 deflection of the mandrel 32. In this embodiment of the invention, the flow ofmaterial is fed into the mold housing 14 downstream of the universal joint so as to prevent the moldable material from interfering with the operation of the joint. In another embodiment of the invention, the flexible joint is simply a less rigid portion of the mandrel 32. That is, the mandrel is attached directly to the 10 mold housing 14 and has a portion which has a reduced flexural stiffness. As a consequence, the applied eccentric offset will result in the bending or flexing of the portion of the mandrel 32 with the reduced stiffness. Those skilled in the art can readily appreciate the variety of modifications to the exemplary embodiments that are possible within the scope of the present invention.
It is also contemplated that the mandrel 32 can be rotated instead of, or in addition to, the rotation of the shaft 20. For example, the drive shaft 20 may be fixedly mounted to the mold housing 14. The flexible joint 68 and the mandrel 32 are then rotated with respect to the drive shaft 20. An eccentricdrive, such as an eccentric portion 20' of the shaft, would be positioned within20 the interior of the mandrel 32 in contact with the inner surface of the mandrel 32. As the mandrel 32 rotates, the eccentric drive displaces the mandrel 32.
The rotation of the mandrel 32 also produces a natural conveyance of the moldable material between the mandrel 32 and the mold die 16. Thus, less pressure from the extruder 12 would be needed to drive the moldable material 25 through the mold die 16. Rotation of the mandrel also results in omni-directional stresses being generated in the material. That is, the displacement of the mandrel 32, in combination with the mandrels rotary motion, impose shear, compressive and tensile loads in various directions. These stresses assist in thoroughly mixing the melt and/or properly controlling the rheological 30 changes and stick-slip behavior of the moldable material. In another 8sl7s96 ~ ~ 85~3~1 embodiment of the invention, the mandrel is non-concentric with the die molds.
Accordingly, rotation of the mandrel results in relative movement between the mandrel and the mold die so as to induce compressive, tensile and shear loads on the moldable material.
In yet another embodiment, the mandrel has two distinct portions which are rotatable with respect to one another. During the molding process, one mandrel portion is rotated in a clockwise direction while the other mandrel portion is rotated in a counter-clockwise direction. As the moldable material flows from one mandrel portion to the other, the counter-rotation of the mandrels causes the material to further mix. In order to prevent the mandrels from separating, a hydraulic cylinder is incorporated to provide a counterforce.It is also possible to rotate both the mandrel 32 and the drive shaft 20 at the same time. In this embodiment, the mandrel 32 can be rotated in the same direction as the drive shaft 20 or in the opposite direction depending on the shear loading that is desired. The mandrel 32 can also be rotated at the same or a different speed than the shaft 20. For example, it may be desirable to step the mandrel 32 around while the drive shaft 20 is continuously rotating.This can be accomplished by lltili7.ing a stepper motor or similar type of driving unit. Alternately, the mandrel 32 and/or drive shaft 20 may be oscillated back and forth instead of completely rotating in one direction. Each of these embodiments produces distinct shear and compressive loads on the moldable material prior to and/or during solidification.
If the mandrel 32 is rotated alone or in conjunction with the drive shaft 20, then it may be desirable to form one or more conveyor flights 150 on the mandrel 32. The conveyor flights 150 would operate similar to the flights 26' on the screw 26. That is, the flights 150 would convey the moldable material between the mandrel 32 and the mold die 16. The incorporation of flights 150 onto the mandrel would reduce the amount of conveying pressure needed by the extruder screw 26. It is also possible to completely elimin~te theextruder and, instead, melt, compress, convey and mix the moldable material \57596 ~85~34 with only the mandrel 32. Alternately, the conveyor flights may be formed on the internal surface of the mold dies 16 to provide the desired flow mixing.
Referring to Figure 18, an alternate embodiment for rotating the mandrel is shown. In this embodiment, the power unit 18 does not drive an 5 internal shaft. Instead, the power unit 18 directly drives the mandrel 32. Therelative displacement between the boundary layers of the material is provided by an eccentric portion of the mandrel 32'. That is, a portion of the mandrel 32' is formed eccentric to the mold housing 14 and/or the mold die 16.
Accordingly, rotation of the mandrel 32 causes the eccentric portion of the 10 mandrel 32' to subject the moldable material flow to compressive, shear and/or tensile loads for mixing the material. Preferably, the eccentric portion of the mandrel 32' is located at a position spaced from the end of the mold die 16.
This permits the post-mixed material to conform to the shape of the mold die 16 while solidifying. Positioning the eccentric portion of the mandrel 32' too 15 close to the end of the mold die 16 could produce inconsistencies in the surface finish. For example, in the illustrated embodiment the eccentric portion of the mandrel 32' is located within a first section of the mold die 16. This is where the compressive, shear and/or tensile loads are applied to the material. The portion of the mandrel located within the downstream portion of the mold die 20 (identified as 16') is concentric with the mold die. This portion of the die mold/mandrel forms the moldable material into its final shape. By incorporating an eccentric portion onto the mandrel 32, it is possible to provide a significant degree of displacement between the mandrel 32 and the mold die 16. Also, more than one eccentric portion can be formed on the mandrel if 25 desired.
Vanes or flow separators (not shown) may be mounted on the mandrel and/or the mold die to add instability to the flow. The instability produces further kn~ ing and mixing of the moldable material flow.
Test samples were prepared using one embodiment of the present 30 invention and compared with a sample made with a standard die molding/mixing \s7596 ~ 1 8S~3~
process. Referring to Figure 9, a sample of colored polystyrene is depicted which was produced using a prior art method. One colored pellet was added to a pound of uncolored polystyrene pellets in a hopper. The components were melted and mixed in a standard extruder and forced though a mold die. The 5 resulting sample had large pockets of uncolored polystyrene (lln~h~ded portion).
Figures 10A and 10B depict two test samples made according to one embodiment of the present invention. In both samples, one colored pellet was placed in the hopper with a pound of uncolored polystyrene. The combination was then melted in the extruder 12 and fed through the mold die 16. An 10 eccentric loading from the drive shaft 20 was imposed on the mandrel 32 so asto generate compressive, tensile and shear loads on the flow of moldable material prior to solidification. As can readily be seen, the samples produced according to the present invention are more thoroughly mixed (less ~ln~h~ded area) than the prior art sample. The differences in mixing between the sample 15 in Figure 10A and the sample in Figure 10B is due to variations in frequency.The sample illustrated in Figure 10A was for a drive shaft running at a low rotational speed and, therefore, low frequency of eccentric loading. While the sample illustrated in Figure 10B was the result of a drive shaft running at highrotational speed and, thus high frequency of eccentric loading. The properties 20 that are desired in the end product will govern the frequency/speed of rotation chosen.
As stated above, the present invention may be utilized to change the rheological properties of the moldable material. By tailoring the amplitude and frequency of the eccentric load, it is possible to modify the physicochemical 25 properties of the moldable material. For example, by properly tailoring the eccentric offset and the speed of the rotation (i.e., frequency) a vibratory load can be imposed on the moldable material so as to increase the resulting flexuraland tensile strength. In the illustrated embodiment, the amount of displacement of the mandrel produced by the combination of the eccentric portion 20' and \57596 2 11 8~Q3~
bearing journal 42 determines the amplitude of the vibratory load and the speed of rotation of the shaft 20 determines the frequency of vibration.
The above embodiments relate to the use of the present invention in a die molding assembly. The present invention, however, can be utilized in various other molding processes, such as blow molding. For example, Figure 11 illustrates the present invention as it is utilized in conjunction with a blow molding assembly 100. The construction and operation of the assembly is generally the same as in the die molding embodiment. However, a conduit 110 is preferably formed through the center of the drive shaft 20. The conduit 110 is attached to and in fluidic communication with a source 112 of a pressurized medium, such as air. A blow mold 114 is positioned at a location downstream from where the moldable material is subjected to the displacement or offset.
During operation, the moldable material is melted and conveyed through the extruder 12 and into the mold housing 14 as discussed above. The lS moldable material is then subjected to a displacement or offset so as to apply compressive, shear and/or tensile loads on the moldable material. After being subjected to the offset, the moldable material is fed into the blow mold 114.
A means for closing off the end of the moldable material so as to form a parison is not shown but may be incorporated into the system and is conventional in the art. When a sufficient quantity of the moldable material is within the blow mold 114, the pressurized media is channeled from the pressure source 112 through the conduit 110 and into the blow mold 114. As a consequence, the moldable material or parison expands onto the surface of the mold.
In each of the above embodiments the extruder 12 has been illustrated as being adjacent to the side of the mold housing 14 and powered by a separate power unit. However, it is also within the purview of the present invention that the screw 26 of the extruder 12 and the drive shaft 20 are drivenby the same power unit. This configuration is illustrated in Figure 12. The flow is first conveyed, compressed and melted along the screw portion 26" of 8110-55 2185~3~1-the shaft. The flow is then directed between the mandrel 32 and the mold die 16. An eccentric portion 20' is formed on the shaft at a downstream location.
Alternately, the screw 26 may have an eccentric portion formed at its downstream end. The eccentric portion would serve to further mix the flow of moldable material. In this alternate embodiment, a drive shaft with an eccentricportion would not be required for mixing the flow since the mixing would occur while the moldable material is being conveyed by the screw.
As stated above, the present invention is not limited to forming circular shaped structures. For example, Figures 13 and 14 illustrate the utilization of the present invention in an assembly 200 for manufacturing flat sheets of material. Figure 13 is an isometric illustration of two parallel flat sheet mold dies 210. A controller 212 provides signals along lines 214 to a driver 216, such as a linear actuator. The driver or linear actuator is in driving contact with one surface of each of the mold dies 210. Actuation of the driver causes deflection of the surfaces in a direction perpendicular to the direction of flow of the moldable material. Figure 14 is a sectional view showing one surface of each of the mold dies 210 conn~ctecl to the linear actuator 216.
These surfaces also attach to a flexible joint 218 which permits the surfaces tobe angularly deflected.
It should be readily apparent that the amount of deflection of the mandrel or inner surface determines the amplitude of the applied vibratory load.Similarly, the frequency of the vibration is determined by the speed of rotationof the drive shaft. By controlling the frequency and amplitude of the applied vibratory load, it is possible to control the rheological properties of the moldable material.
Referring now to Figure 16, an embodiment of the present invention is illustrated wherein reinforcing fibers are fed into the moldable material prior to mixing. As discussed above, the prior art devices add reinforcing fibers either when the material is in the hopper or while the material is conveying through the extruder. In Figure 16, a fiber feeding assembly 400 8110-55 2 1 ~S~3~
\57596 is shown which feeds reinforcing fibers directly into the melt prior to mixing and after conveyance by the extruder. The fiber feeding assembly 400 includes a conveyor 402 mounted between the extruder port 28 and the mold housing 14.
The conveyor 402 translates in a direction (as shown by the arrow) which is at S an angle to the material flow so as to locate at least a portion of the conveyor 402 within the material flow. Preferably the direction of travel of the conveyor402 is about 90 to the direction of flow. The conveyor 402 can be translated in a reciprocating manner or, alternately, may be a unidirectional feed. In the latter case, the conveyor 402 may be supplied in the form of a large spool or, 10 more preferably, may be a continuous belt. A power source (not shown) may be used to control the travel of the conveyor 402. The speed of the conveyor 402 may be controlled so as to be proportional to the extruder motor and/or anticipated speed of the material flow.
As shown in the figure, the conveyor 402 has a plurality of open cells 404 formed through it. The open cells 404 are oriented so as to permit themolten material to flow therethrough when the conveyor 402 is placed within the flow. Short or chopped fibers 406 are deposited within the open cells 404.
A vacuum source 407 is preferably utilized to draw the chopped fibers into the open cells. Once the cells 404 are filled with the fibers 406, the conveyor 402 is translated so as to placed the filled cells 404 within the material flow.
Accordingly, as the molten material passes through the open cells 404 it picks up the loose fibers 406. The combination of the molten material and the fibers then enters into the mold housing 14 wherein the fibers are thoroughly mixed with the molten material.
In one preferred embodiment, the conveyor 402 is a continuous screen changer. Continuous screen changers are used in molding devices to filter out cont~min~nt~ from the molten material as it flows through the screen.One suitable type of continuous screen changer is produced by High Technology Corp., Hackensack, New Jersey. The present invention uses the continuous \57596 ~ 5~34 screen changer to incorporate the reinforcing fibers 406 into the melt while at the same time removing any cont~min~nt~ in the flow.
In an alternate configuration shown in Figure 17, the fiber feeding assembly is designed to incorporate long reinforcing fibers into the S material flow. A conveyor 410 is again mounted between the extruder port 28 and the mold housing 14. The conveyor 410 travels in a direction, as shown by the arrow, which is preferably at an angle to the material flow. As with the configuration discussed above, the conveyor 410 is preferably a continuous screen changer for filtering cont~min~tçs out of the material flow. Long reinforcing fibers 412 are positioned on the downstream side of the conveyor 410 prior to placement within the material flow. Accordingly, when the conveyor 402 is translated through the material flow, the reinforcing fibers 412are picked off the conveyor 410 by the flow of material and carried along into the mold housing for further mixing. One method for attaching the fibers 412 to the conveyor 410 is through the use of a vacuum source 414. The vacuum source 414 draws the fibers 412 against the downstream surface of the conveyor 410. Alternate methods for feeding the reinforcing fibers into the material flowmay be substituted for the disclosed embodiments and are well within the purview of the claims.
Although the invention has been described and illustrated with respect to the exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.
A problem with existing molding processes is the inability to simply and inexpensively provide thorough mixing of two constituent parts of a moldable material. For example, the moldable material may consist of a base polystyrene component material and a coloring agent. Alternately, the constituent components could be a base resin or matrix material and an additive or curing agent which, when mixed, form a moldable material as in a thermoset material. A variety of other examples of moldable materials exist which consist of two or more combined components and which must be mixed to form the final product. In the prior art processes, mixing of the two components was typically achieved either in a hopper or while conveyed by designated processing machinery. In either case, it is important that the mixing be thorough in order to achieve a structurally or cosmetically acceptable final product. The uniformity in color of a final molded product is extremely important in today's commercial marketplace. Since many products are ultimately selected by a consumer based on their appearance, m:~mlf~cturers strive to distinguish their products through specific coloring. The inefficient manufacturing processes discussed above are perceived as drawbacks by these manufacturers for generating the desired coloring.
Another problem with the prior art processes occurs when only a small amount of one constituent is to be mixed with a large amount of a second constituent. In this situation, the utilization of only the hopper to mixthe two constituents may not result in a homogeneous mixture. For example, only one or two color pellets are typically needed to sufficiently color one pound of uncolored polystyrene pellets. However, simply mixing one or two \57596 2 ~ 8SQ~9 unmelted colored pellets into thousands of unmelted uncolored polystyrene pellets and then melting the mixture will not provide an even color distributionin the final product.
The prior art processes are also inefficient when it is desirable to combine dissimilar components which do not readily and easily mix with one another. In order to produce the desired mixing, the prior art processes mix thematerials for an extended period of time or subject the materials to additional m~mlf~cturing steps.
The screw in an extruder is generally used to provide additional mixing of the constituent parts. The flights on the screw, acting in conjunctionwith walls of the extruder barrel, produce a rolling or kn~a(ling of the moldable material as it is melted, compressed and driven toward the exit of the extruder.If a single screw does not provide sufficient mixing, multiple intermeshing screws are utilized. The intermeshing of the screw flights more thoroughly kneads the constituent parts of the material into a single homogeneous mixture.
A drawback to the use of multiple screws is the need for a complicated drive mechanism for rotating the multiple screws. Furthermore, the multiple screws produce excessive heat and compression of the moldable material, resulting in degradation of the material.
In order to compensate for the inefficient mixing that occurs with the prior art processes, excessive amounts of one or more component part of the moldable material are sometimes added. For example, as discussed above, one or two coloring agent pellets would, under proper mixing conditions, be sufficient to color a pound of uncolored polystyrene pellets. However, since most mixing systems do not adequately mix the component materials, it is typically required that more coloring pellets be used per pound of uncolored polystyrene. This increases the cost of manufacturing the final colored product.Another problem in the prior art relates to mixing of recyclable materials. There is a trend to increase the amount of recyclable material 30 incorporated into a final molded part. In many instances, the recyclable \57596 ~8s~3q material must be combined with virgin material prior to solidification. If the recycled material is not adequately mixed with the virgin material, flaws or we~kn~sses can develop in the final product.
The prior art devices are also deficient when it is desired to mix 5 multicomponent systems with more than one polymer component (e.g., rubber or plastic) and/or more than one additive. For example, prior art devices do notefficiently mix filler material, such as reinforcing materials or plasticizers, which are used to improve one or more of the properties of the final product.
Prior art devices incorporate dry reiforcing fibers into the material either in the 10 hopper or while in the extruder barrel. Neither method provides an effective method for reiforcing the material. On the contrary, mixing the fibers with the molten material prior to or during conveyance in the extruder causes fiber breakage and excessive extruder wear. To minimi7e the damage to the extruder, prior art devices incorporate the fibers near the end of the screw.
15 However, this results in poor mixing of the plies into the melt and still results in wear of the last few flights of the extruder screw.
A need therefore exists for an appa~ s and system which facilitates the mixing and transformation of a moldable material prior to and/orduring solidification. Furthermore, a need exists for a system for reinforcing 20 a moldable material flow without causing excessive wear of the extruder screw.
Sumrnary of the Invention The present invention relates to an al~par~lus and a system for subjecting a flow of moldable material to shear, compressive 25 and/or tensile loads.
In another aspect the present invention provides an app~lus and system for thoroughly mixing a flow of moldable material.
- In yet another aspect the present invention provides an apparatus and system for displacing a flow of moldable material so as to 30 produce mixing of the material.
~- \S7596 ~1 ~5~34 These and other aspects and advantages of the present invention are achieved by the novel apparatus and system for molding a flow of moldable material under the application of shear, compressive and/or tensile loads. The apparatus comprises a mold housing that has a flow of moldable material S supplied to it. A first boundary element is located within the mold housing and defines a first side of the flow of moldable material. A second boundary element also positioned within the mold housing defines a second side of the flow of moldable material. A driver in driving contact with the first boundary element is adapted to produce a deflection of the first boundary element in a 10 direction subst~nti~lly perpendicular to the flow of the moldable material. The deflection of the first boundary element imposes shear, compressive and tensile loads on the flow which function to transform the moldable material. In one embodiment of the invention, the applied shear, compressive and tensile loads produce mixing of the moldable flow of material. In another embodiment of the 15 invention, the shear, compressive and tensile loads are controlled for effecting the rheological properties of the moldable material prior to and during curing.
The imposed forces also function to increase the mixing of the moldable flow without the need for further mixing devices.
A flexible joint is incorporated into the apparatus to allow the 20 first boundary element to deflect. In one embodiment of the invention, the flexible joint is configured as a cylindrical wave or bellows. This cylindrical wave attaches to the first boundary element or mandrel which may also be cylindrical in shape.
In one configuration, the driver comprises an eccentric portion 25 of a drive shaft. The rotation of the drive shaft causes the eccentric portion to rotate eccentric to the shaft's axis of rotation. This eccentric rotation causes the deflection of the first boundary element. The amount of deflection may be varied as desired by means of a bearing assembly which includes a rotatable eccentric bearing journal.
85l75965 2 ~ ~03~
A system for transforming a flow of moldable material is also disclosed. The system includes the steps of mixing a first material component and a second material component so as to produce a mixture. The mixture is then melted to form a moldable material. The moldable material is conveyed 5 between a first and second boundary element of a molding apparatus. A portion of the first boundary element is deflected in a direction substantially perpendicular to the flow of moldable material. The deflection of the first boundary element imposes shear, compressive and tensile loads on the flow of moldable material which produce further mixing of the moldable material. The 10 moldable material is then cured into a final product.
The novel apparatus and system result in moldable material which is more thoroughly and efflciently mixed than has heretofore been possible by prior art processes. The novel apparatus and system also controls the rheological properties of the moldable material for reducing the residual stress15 and/or elimin~ting the melt fracture in the final product.
The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof, as illustrated in the accompanying figures.
Brief Description of the Dldwi~
For the purpose of illustrating the invention, the drawings show a form of the invention which is presently preferred. However, it should be understood that this invention is not limited to the precise arrangements and 25 instrumentalities shown in the drawings.
Figure 1 illustrates the present invention as it is utilized in a die molding system.
Figure 2 is a section view of an extruder used to feed a moldable material into a die housing.
\57596 2 1 ~5~34 Figure 3 is a schematic representation of a prior art molding apparatus.
Figures 4A-4D are schematic representations of a molding apparatus made according to the present invention for use in applying shear and 5 colllplessive loads to a flow of moldable material.
Figure 5 is a detail view of one arrangement of the driver for use in deflecting or eccentrically offsetting a mold surface.
Figure 6 is a section view of the molding apparatus taken along lines 6-6 in Figure S.
Figure 7 is a side view of the molding apparatus taken along lines 7-7 in Figure 5.
Figure 8 is a detail view of one arrangement of the flexible joint for accommodating the deflection of the mandrel.
Figure 9 is a illustration of a test sample produced according to a prior art method.
Figures lOA and lOB illustrate two test samples produced according to one embodiment of the present invention.
Figure 11 illustrates an embodiment of the present invention as it is utilized in a blow molding system.
Figure 12 illustrates an embodiment of the present invention wherein the extruder and the drive shaft are formed as an integral unit.
Figure 13 illustrates an embodiment of the present invention as it is utilized in fabricating flat die molded sheets of material.
Figure 14 illustrates a section view of the flat die molded sheet embodiment of the present invention.
Figures l5A and l5B illustrate two eccentric positions of the driver for use in deflecting or eccentrically offsetting a mold surface.
Figure 16 illustrates an embodiment of the present invention for use in m~mlf~cturing a molded product made with fiber reinforced molded material.
` \57596 ~ g3 Figure 17 illustrates another embodiment of the present invention for use in m~nllfacturing a molded product made with fiber reinforced molded material.
Figure 18 illustrates an embodiment of the present invention S wherein the mandrel is eccentric with respect to the die mold.
Detailed Des~ Jtion of the Preferred Embodillle--ls Referring now to the drawings, wherein like reference numerals illustrate corresponding or similar elements throughout the several views, Figure 10 1 illustrates one embodiment of the present invention as it is incorporated in a die molding assembly 10. The die molding assembly 10 includes an extruder 12, a mold housing 14, and one or more mold dies 16. A power unit 18 is used to rotate an internally mounted drive shaft 20 which will be discussed in more detail below.
The extruder 12 is illustrated in more detail in Figure 2. The extruder 12 generally includes a hopper 22 for supplying a preferably unmelted, fungible moldable material into a extruder housing or barrel 24. A screw 26 is located within the extruder barrel 24 and is rotated by a motor drive 27. Thescrew 26 contains one or more flights 26' which, when the screw is rotated, 20 drive or feed the moldable material from the hopper 22 to an extruder port 28in the extruder barrel 24. The screw 26 also functions to melt, compress and homogenize the moldable material during translation from the hopper 22 to the port 28. At least one heater 30 is located on or adjacent to the extruder barrel24. The heater 30 transmits heat to the moldable material causing it to melt as 25 it is translated by the screw 26 to the port 28.
In one plerelled embodiment, the extruder port 28 directs the flow of moldable material from the extruder 12 into the mold housing 14. A
flow divider (not shown) channels the incoming flow of moldable material into the mold dies 16 which define the external shape or boundary of the final 30 product. In the embodiment illustrated, the mold dies 16 define the external \57596 ~ 1 85~3~
surface of a cylindrical tube. A mandrel 32 is located within the die molds 16 and forms an internal mold boundary along which the moldable material flows.
Hence, in this embodiment, the moldable material flows or is channeled between the inner surface of the outer mold dies 16 and the outer surface of theS inner mandrel 32 which define the final product shape. In the illustrated embodiment, the final product shape is a tube or cylinder such as a pipe.
Alternate shapes may also be practiced within the scope of the invention.
As discussed above, the screw 26 compresses and conveys the moldable material while in the extruder 12. The moldable material is fed into the mold housing and is forced to flow between the mold dies 16 and the mandrel 32 by pressure from the continuous rotation of the screw 26. Hence, the speed of the screw 26 determines the speed that the final product is output from the die molding assembly 10.
A series of temperature control units (not shown) may be positioned on or adjacent to the outer surface of the die molds 16. Both coolingand heating of the moldable material can be applied through the temperature control units. Those skilled in the art would readily be able to determine whether to cool or heat the material depending on the specific material being processed and/or the objectives sought. For example, cooling can be applied to shorten the solidification or curing time of the moldable material. Although the mold dies 16 are depicted as being relatively long in length, it should be appreciated that the desired length will depend at least on the amount of cooling required to solidify or cure the final molded product, and on the final product shape.
In order to more thoroughly mix the component parts of the moldable material, the present invention subjects the flow of moldable material to a load or deflection which is substantially perpendicular to the direction ofmaterial flow so as to impose compressive and shear loads on the flow.
Referring to Figure 1, in one embodiment of the invention, the material flowing between the mandrel 32 and the mold die 16is subjected to force caused by the \57596 as~34 eccentric rotation of a portion of the internal drive shaft 20. That is, a portion of the internal drive shaft 20 is eccentric to and in driving contact with the mandrel 32 so as to function as an eccentric driver. The eccentric driver produces an eccentric motion or deflection of the mandrel 32 with respect to thelongitudinal axis of rotation of the shaft so as to result in relative motion between the mandrel 32 and the die mold 16. This motion or deflection of the mandrel 32 is substantially perpendicular to the axial direction of the flow of moldable material between the mandrel 32 and the mold die 16. The deflection of the mandrel 32, in turn, subjects the flow of moldable material to shear, compressive, and tensile forces which result in further mixing of the moldable material just prior to and during solidification.
A better underst~n(ling of this eccentric motion can be had by reference to Figures 3 and 4A-4D. Figure 3 illustrates a section view of a priorart die mold system during operation. The mandrel 32 is concentric with the mold die 16. There is no internally mounted drive shaft since the prior art die molding assemblies typically do not apply rotational motion to the mandrel or the mold dies. As a consequence, there are no forces applied to the flow of moldable material (designated by numeral 34) by eccentric rotation of a drive shaft.
Referring to Figures 4A-4D, one embodiment of the present invention is shown wherein the drive shaft exerts an eccentric motion on the mandrel 32. Figures 4A-4D show the rotation of the drive shaft in 90 degree increments. In the embodiment illustrated, a portion 20' of the internal drive shaft 20 rotates eccentric to the shaft's longitudinal axis of rotation (designated by numeral 36 and shown in Figure 1). The eccentricity, 'e', is shown in Figure 1. As the eccentric portion 20' rotates, it deflects the mandrel 32 causing the mandrel 32 to move toward and away from the die mold 16. This motion produces compression, tension and shear forces in at least a portion of the moldable material flow 34. These applied compression, tension and shear \57596 ~18~
forces produce, as one consequence, an omni-directional mixing of the moldable material.
The applied compression, tension and shear forces also produce changes in the rheological properties of the molten material. That is, the S eccentricity of the drive shaft 20 with respect to the mandrel 32 can be tailored to produce compression and shear forces in the moldable material which, for example, alter the orientation and/or the flexural and tensile strength of the material. Transforming the physical characteristics of a moldable material is well known and is described in detail in U.S. Pat. Nos. 4,469,649 and 5,306,129 which are both incorporated herein by reference. The disclosed embodiments provide a novel means for achieving the change in the rheological properties of the material. It is contemplated that a controller may be utilizedto control the eccentric driving to produce the desired rheological properties.
Those skilled in the art would readily be capable of l]tili7ing the teaching of the 15 present invention for altering the rheological properties of the moldable material and, therefore, no further discussion is needed.
It is also well known that, during the flow process, molten polymers store a significant amount of elastic energy when subjected to pressure, such as from the screw of an extruder. This stored elastic energy in 20 the polymer melt could cause a high level of residual stress, die swell and/or melt fracture in the final molded article. The application of the compressive, tensile and shear loads on the molten polymer prior to and/or during solidification or curing can be used to control the level of elastic "memory" byinducing relaxation of the polymer molecules. This would result in the control 25 of the residual stress and/or elimin~tion of the melt fracture in the final molded part. Prior art methods of reducing the residual stress or melt fracture stress included reducing the applied pressure, increasing molding cycle time, ~nn~ling the molded article after it is already molded, etc. The present invention elimin~tes or reduces the need for such expensive and time-consuming 30 m~m-f~blring solutions.
\57596 ~ 1 35~3q As stated above, in one embodiment of the invention, a portion of the drive shaft 20 is formed eccentric to the longitll~lin~l axis of rotation 36 of the shaft. This embodiment is shown in Figures 1 and 5. As illustrated in Figure 5 and discussed above, the eccentric portion 20' of the drive shaft has a centerline 38 that is eccentric to the axis of rotation 36 of the shaft 20.
The eccentric portion 20' of the shaft is engaged with the mandrel 32 by means of a bearing assembly 40. The bearing assembly 40 includes a bearing journal 42 which has an inner surface 44 disposed around an outer surface 46 of the eccentric portion 20'. The bearing journal 42 also has an outer surface 48 which is in contact with an inner race 50 of a bearing 52.
Generally a tight fit is desired between the bearing journal 42 and the inner race 50 of the bearing 52 such that rotation of the bearing journal 42 produces rotation of the inner race 50. The bearing 52 also has an outer race 54 which is located between the inner race 50 and an inner wall or surface 56 of the mandrel 32. Preferably the outer race 54 is fit snug against the inner wall 56 of the mandrel 32 so as to prohibit or minimi7e motion therebetween.
Alternately, a second bearing journal (not shown) could be located between the outer race 54 and the mandrel 32 to minimi7e the size of the bearing needed.
The bearing assembly 40 permits the drive shaft 20 and eccentric portion 20' to rotate with respect to the mandrel 32 while m~int~ining engagement between the eccentric portion 20' and the mandrel 32.
In the illustrated embodiment, it is desirable that the bearing journal 42 rotate with the drive shaft 20. To achieve this, the bearing journal 42 may be directly locked into engagement with the drive shaft 20 and/or the eccentric portion 20' by means of a screw or pin 58 (shown in Figure 6).
Alternately and more preferably, a locking mechanism 60 may be utilized to attach the bearing journal 42 to the eccentric portion 20'. Referring to Figures5 and 7, the locking mechanism 60 is positioned adjacent to the bearing journal 42 and is disposed around the eccentric portion 20' of the shaft. The locking mechanism 60 is attached to the bearing journal 42 by means of the pin 58.
\SîS96 2 1 ~34 The locking mechanism 60 furthermore has a slot 62 formed therein, the width of which can be adjusted by a locking screw 64. Tightening of the locking screw 64 causes the width of the slot 62 to decrease. This, in turn, causes the locking mechanism to tighten around the eccentric portion 20 ' of the drive shaft.
5 As a result, rotation of the drive shaft 20 produces corresponding rotation of the bearing journal 42 and the inner race 50 of the bearing.
Alternate methods for eng~ging the eccentric portion 20' with the mandrel 32 are also within the purview of this invention. For example, the inner race 50 of the bearing 52 could be disposed directly on the outer surface 46 of the eccentric portion 20' elimin~ting the need for a bearing journal 42.
Furthermore, in an alternate arrangement, the locking mechanism 60 may be formed integral with the bearing journal 42 or, instead, the bearing journal could be attached to the eccentric portion 20' through a splined, keyed or similar type arrangement. In still yet another embodiment, a cam arrangement 15 similar to the one shown in Figures 4A-4D may be incorporated into the invention for functioning as the eccentric driver to produce the offset of the mandrel 32. It is also contemplated that the drive shaft can be formed without an eccentric portion 20'. Instead, the eccentric driver for producing the offsetof the mandrel is attached directly to the mandrel 32 itself. For example, the 20 bearing 52 can be mounted to the mandrel 32 in a non-concentric manner.
Normal rotation of the drive shaft 20 would result in the eccentric motion of the mandrel 32.
In one embodiment of the die molding assembly, the eccentricity e of the shaft 20 is preset and non-adjustable. In this embodiment, the bearing 25 journal 42 is shaped such that its outer surface 48 is concentric with the outer surface 46 of the eccentric portion 20'. As a result, the mandrel 32 will alwaysbe eccentrically driven by the drive shaft 20.
In a second, and more preferable, embodiment the amount of eccentricity e produced by the driver is adjustable depending on the amount and 30 type of loading desired on the moldable material. For example, in one \57596 ~ 1Q34j configuration, the eccentricity is adjustable from about zero inches to more than 0.125 inches. The amount of adjustability will, of course, differ depending on the configuration of the molding process and the shape of the resulting product.In order to achieve this variability in eccentricity, the outer surface 48 of the 5 bearing journal 42 has a shape which is not concentric with the outer surface 46 of the eccentric portion 20'. This bearing journal configuration is illustrated in Figures 5 and 6. It should be apparent that rotation of the bearing journal 42 with respect to the eccentric portion 20' will alter the amount that the mandrelis displaced or eccentrically offset. The combination of the bearing journal 42 and the eccentric portion 20' define a driver centerline 300. The amount of deflection of the mandrel 32 is a function of the distance between the driver centerline 300 and the longitudinal axis of rotation 36 of the shaft 20. Figure 15A illustrates one position of the bearing journal 42 and eccentric portion 20'combination. In this position, the driver centerline 300 lies substantially in line 15 with the longitlldin~l axis of rotation 36 of the shaft 20. Accordingly, there is substantially no eccentric offset of the mandrel 32 by the eccentric driver.
Figure 15B illustrates the bearing journal rotated into a second position. In this position, the driver centerline 300 is spaced apart from the longitudinal axis of rotation 36 of the shaft 20 by an eccentric distance e. Accordingly, the 20 eccentric offset of the mandrel 32 will be a function of this eccentricity e.Varying the eccentricity e, produces varying compression, tension and shear loads on the flow of moldable material.
In order to rotate the bearing journal 42 with respect to the eccentric portion 20', the locking mechanism 60 has flat surfaces 66 formed on 25 it to permit grasping of the locking mechanism 60 by a wrench or similar typeimplement. The drive shaft 20 is held in place while the locking mechanism 60 and the bearing journal 42 are rotated to produce the desired eccentricity e.
In the alternate splined or keyed arrangement discussed above, the bearing journal 42 is engaged with the proper splines or keys on the 30 eccentric portion 20' so as to provide the desired eccentricity e. In the alternate \57596 ~ I ~S~ ~4-embodiment discussed above where the bearing journal 42 is pinned directly into the drive shaft 20, multiple pin holes could be formed in the drive shaft in a circumferential pattern, each hole representing a different eccentric position.
Accordingly, the bearing journal would be pinned into the appropriate hole to 5 provide the desired eccentricity. It is also contemplated that the eccentric portion 20' of the shaft be removable such that portions with different eccentricities may be substituted as needed. Alternately, a portion of the mandrel 32 itself could be formed non-concentric with the die mold 16. Motion of the mold (e.g., rotational or lateral) would result in compression and shear 10 loads being applied to the moldable material flow. Those skilled in the art would readily appreciate the various alternate methods of adjusting the eccentricity that can be practiced within the scope of this invention. For example, a motor drive (not shown) could be mounted within the mandrel 32 for permitting automated adjustment of the eccentricity e.
As discussed above, rotation of the drive shaft 20 causes the eccentric portion 20' to produce a deflection or eccentric offset of the mandrel32. In the embodiment illustrated in Figure 1, the eccentric offset of the mandrel 32 occurs at a location apart from the point where the mandrel 32 attaches to the mold housing 14 and where the extruder 12 feeds the moldable 20 material into the mold housing 14. In order to permit the mandrel 32 to be displaced, the end of the mandrel 32 closest to the point where the moldable material enters the mold housing 14 is attached to the mold housing 14 through a flexible joint 68. The flexible joint 68 permits the mandrel 32 to remain relatively straight. Tn~te~(l, the offset or displacement of the mandrel 32 is 25 accommodated by angular flexure of the flexible joint 68. The flexible joint 68 preferably also biases the mandrel back to its undeflected position.
The incorporation of the flexible joint 68 reduces or elimin~tes the stresses which would otherwise develop in the mandrel 32 from the eccentric offset or deflection. Additionally, the angular flexure of the flexible joint and 30 resulting angular orientation of the mandrel 32 subject the flow of moldable \57596 ~ 1 85b34 material to an additional axial shear force which acts along substantially the entire longitl-~lin~l length of the mandrel 32. This added shear force helps to mix the moldable material and reduce the slip-stick behavior of the flow.
In one preferred embodiment, the flexible joint 68 comprises an internal wave 70 similar to a bellows. This type of configuration permits the internal wave 70 to flex radially in all directions. The bellows shape also allows the moldable material to flow relatively unobstructed through the mold housing 14 and onto the mandrel 32. During a standard molding process, pressures of up to 10,000 psi can be generated as the extruder 12 forces the moldable material into the mold housing 14. Accordingly, the internal wave 70 must be designed to with~t~nfl this applied pressure while also permitting the required angular flexure produced by the displacement of the mandrel 32. In the preferred embodiment, the internal wave 70 is made from 17-4PH stainless steel with a thickness of about 0.125 inches. A variety of other configurations and materials may be substituted for the preferred embodiment. For example, the wave could instead be constructed from fiber reinforced composite matrix material.
Referring to Figures 1 and 8, the internal wave 70 is attached to the mandrel 32 preferably through a threaded arrangement designated by the numeral 72. Alternate methods for attaching the mandrel 32 to the internal wave 70 can be utilized in the present invention. However, the selected method of attaching the mandrel 32 to the internal wave 70 should be designed to prevent or minimi7~ leakage of the moldable material into the interior of the mandrel 32 and onto the drive shaft 20 and its associated bearings.
The internal wave 70 is preferably attached to the mold housing 14 by means of a spindle 74. The spindle 74 is positioned within the flow divider (not shown) and can be threadingly engaged with the internal wave 70 or, as shown in the figure, can attach the internal wave 70 to the mold housing through a thrust type arrangement. Axial adjustment of the spindle 74 pulls the internal wave 70 toward the mold housing 14. Bearings 76 are located between \57596 - ~ ~ 35~34 the spindle 74 and the drive shaft 20 so as to permit the shaft 20 to rotate within the spindle 74.
Alternately, the flexible joint 68 may comprise a universal joint arrangement (not shown). The universal joi~t accommodates the angular 5 deflection of the mandrel 32. In this embodiment of the invention, the flow ofmaterial is fed into the mold housing 14 downstream of the universal joint so as to prevent the moldable material from interfering with the operation of the joint. In another embodiment of the invention, the flexible joint is simply a less rigid portion of the mandrel 32. That is, the mandrel is attached directly to the 10 mold housing 14 and has a portion which has a reduced flexural stiffness. As a consequence, the applied eccentric offset will result in the bending or flexing of the portion of the mandrel 32 with the reduced stiffness. Those skilled in the art can readily appreciate the variety of modifications to the exemplary embodiments that are possible within the scope of the present invention.
It is also contemplated that the mandrel 32 can be rotated instead of, or in addition to, the rotation of the shaft 20. For example, the drive shaft 20 may be fixedly mounted to the mold housing 14. The flexible joint 68 and the mandrel 32 are then rotated with respect to the drive shaft 20. An eccentricdrive, such as an eccentric portion 20' of the shaft, would be positioned within20 the interior of the mandrel 32 in contact with the inner surface of the mandrel 32. As the mandrel 32 rotates, the eccentric drive displaces the mandrel 32.
The rotation of the mandrel 32 also produces a natural conveyance of the moldable material between the mandrel 32 and the mold die 16. Thus, less pressure from the extruder 12 would be needed to drive the moldable material 25 through the mold die 16. Rotation of the mandrel also results in omni-directional stresses being generated in the material. That is, the displacement of the mandrel 32, in combination with the mandrels rotary motion, impose shear, compressive and tensile loads in various directions. These stresses assist in thoroughly mixing the melt and/or properly controlling the rheological 30 changes and stick-slip behavior of the moldable material. In another 8sl7s96 ~ ~ 85~3~1 embodiment of the invention, the mandrel is non-concentric with the die molds.
Accordingly, rotation of the mandrel results in relative movement between the mandrel and the mold die so as to induce compressive, tensile and shear loads on the moldable material.
In yet another embodiment, the mandrel has two distinct portions which are rotatable with respect to one another. During the molding process, one mandrel portion is rotated in a clockwise direction while the other mandrel portion is rotated in a counter-clockwise direction. As the moldable material flows from one mandrel portion to the other, the counter-rotation of the mandrels causes the material to further mix. In order to prevent the mandrels from separating, a hydraulic cylinder is incorporated to provide a counterforce.It is also possible to rotate both the mandrel 32 and the drive shaft 20 at the same time. In this embodiment, the mandrel 32 can be rotated in the same direction as the drive shaft 20 or in the opposite direction depending on the shear loading that is desired. The mandrel 32 can also be rotated at the same or a different speed than the shaft 20. For example, it may be desirable to step the mandrel 32 around while the drive shaft 20 is continuously rotating.This can be accomplished by lltili7.ing a stepper motor or similar type of driving unit. Alternately, the mandrel 32 and/or drive shaft 20 may be oscillated back and forth instead of completely rotating in one direction. Each of these embodiments produces distinct shear and compressive loads on the moldable material prior to and/or during solidification.
If the mandrel 32 is rotated alone or in conjunction with the drive shaft 20, then it may be desirable to form one or more conveyor flights 150 on the mandrel 32. The conveyor flights 150 would operate similar to the flights 26' on the screw 26. That is, the flights 150 would convey the moldable material between the mandrel 32 and the mold die 16. The incorporation of flights 150 onto the mandrel would reduce the amount of conveying pressure needed by the extruder screw 26. It is also possible to completely elimin~te theextruder and, instead, melt, compress, convey and mix the moldable material \57596 ~85~34 with only the mandrel 32. Alternately, the conveyor flights may be formed on the internal surface of the mold dies 16 to provide the desired flow mixing.
Referring to Figure 18, an alternate embodiment for rotating the mandrel is shown. In this embodiment, the power unit 18 does not drive an 5 internal shaft. Instead, the power unit 18 directly drives the mandrel 32. Therelative displacement between the boundary layers of the material is provided by an eccentric portion of the mandrel 32'. That is, a portion of the mandrel 32' is formed eccentric to the mold housing 14 and/or the mold die 16.
Accordingly, rotation of the mandrel 32 causes the eccentric portion of the 10 mandrel 32' to subject the moldable material flow to compressive, shear and/or tensile loads for mixing the material. Preferably, the eccentric portion of the mandrel 32' is located at a position spaced from the end of the mold die 16.
This permits the post-mixed material to conform to the shape of the mold die 16 while solidifying. Positioning the eccentric portion of the mandrel 32' too 15 close to the end of the mold die 16 could produce inconsistencies in the surface finish. For example, in the illustrated embodiment the eccentric portion of the mandrel 32' is located within a first section of the mold die 16. This is where the compressive, shear and/or tensile loads are applied to the material. The portion of the mandrel located within the downstream portion of the mold die 20 (identified as 16') is concentric with the mold die. This portion of the die mold/mandrel forms the moldable material into its final shape. By incorporating an eccentric portion onto the mandrel 32, it is possible to provide a significant degree of displacement between the mandrel 32 and the mold die 16. Also, more than one eccentric portion can be formed on the mandrel if 25 desired.
Vanes or flow separators (not shown) may be mounted on the mandrel and/or the mold die to add instability to the flow. The instability produces further kn~ ing and mixing of the moldable material flow.
Test samples were prepared using one embodiment of the present 30 invention and compared with a sample made with a standard die molding/mixing \s7596 ~ 1 8S~3~
process. Referring to Figure 9, a sample of colored polystyrene is depicted which was produced using a prior art method. One colored pellet was added to a pound of uncolored polystyrene pellets in a hopper. The components were melted and mixed in a standard extruder and forced though a mold die. The 5 resulting sample had large pockets of uncolored polystyrene (lln~h~ded portion).
Figures 10A and 10B depict two test samples made according to one embodiment of the present invention. In both samples, one colored pellet was placed in the hopper with a pound of uncolored polystyrene. The combination was then melted in the extruder 12 and fed through the mold die 16. An 10 eccentric loading from the drive shaft 20 was imposed on the mandrel 32 so asto generate compressive, tensile and shear loads on the flow of moldable material prior to solidification. As can readily be seen, the samples produced according to the present invention are more thoroughly mixed (less ~ln~h~ded area) than the prior art sample. The differences in mixing between the sample 15 in Figure 10A and the sample in Figure 10B is due to variations in frequency.The sample illustrated in Figure 10A was for a drive shaft running at a low rotational speed and, therefore, low frequency of eccentric loading. While the sample illustrated in Figure 10B was the result of a drive shaft running at highrotational speed and, thus high frequency of eccentric loading. The properties 20 that are desired in the end product will govern the frequency/speed of rotation chosen.
As stated above, the present invention may be utilized to change the rheological properties of the moldable material. By tailoring the amplitude and frequency of the eccentric load, it is possible to modify the physicochemical 25 properties of the moldable material. For example, by properly tailoring the eccentric offset and the speed of the rotation (i.e., frequency) a vibratory load can be imposed on the moldable material so as to increase the resulting flexuraland tensile strength. In the illustrated embodiment, the amount of displacement of the mandrel produced by the combination of the eccentric portion 20' and \57596 2 11 8~Q3~
bearing journal 42 determines the amplitude of the vibratory load and the speed of rotation of the shaft 20 determines the frequency of vibration.
The above embodiments relate to the use of the present invention in a die molding assembly. The present invention, however, can be utilized in various other molding processes, such as blow molding. For example, Figure 11 illustrates the present invention as it is utilized in conjunction with a blow molding assembly 100. The construction and operation of the assembly is generally the same as in the die molding embodiment. However, a conduit 110 is preferably formed through the center of the drive shaft 20. The conduit 110 is attached to and in fluidic communication with a source 112 of a pressurized medium, such as air. A blow mold 114 is positioned at a location downstream from where the moldable material is subjected to the displacement or offset.
During operation, the moldable material is melted and conveyed through the extruder 12 and into the mold housing 14 as discussed above. The lS moldable material is then subjected to a displacement or offset so as to apply compressive, shear and/or tensile loads on the moldable material. After being subjected to the offset, the moldable material is fed into the blow mold 114.
A means for closing off the end of the moldable material so as to form a parison is not shown but may be incorporated into the system and is conventional in the art. When a sufficient quantity of the moldable material is within the blow mold 114, the pressurized media is channeled from the pressure source 112 through the conduit 110 and into the blow mold 114. As a consequence, the moldable material or parison expands onto the surface of the mold.
In each of the above embodiments the extruder 12 has been illustrated as being adjacent to the side of the mold housing 14 and powered by a separate power unit. However, it is also within the purview of the present invention that the screw 26 of the extruder 12 and the drive shaft 20 are drivenby the same power unit. This configuration is illustrated in Figure 12. The flow is first conveyed, compressed and melted along the screw portion 26" of 8110-55 2185~3~1-the shaft. The flow is then directed between the mandrel 32 and the mold die 16. An eccentric portion 20' is formed on the shaft at a downstream location.
Alternately, the screw 26 may have an eccentric portion formed at its downstream end. The eccentric portion would serve to further mix the flow of moldable material. In this alternate embodiment, a drive shaft with an eccentricportion would not be required for mixing the flow since the mixing would occur while the moldable material is being conveyed by the screw.
As stated above, the present invention is not limited to forming circular shaped structures. For example, Figures 13 and 14 illustrate the utilization of the present invention in an assembly 200 for manufacturing flat sheets of material. Figure 13 is an isometric illustration of two parallel flat sheet mold dies 210. A controller 212 provides signals along lines 214 to a driver 216, such as a linear actuator. The driver or linear actuator is in driving contact with one surface of each of the mold dies 210. Actuation of the driver causes deflection of the surfaces in a direction perpendicular to the direction of flow of the moldable material. Figure 14 is a sectional view showing one surface of each of the mold dies 210 conn~ctecl to the linear actuator 216.
These surfaces also attach to a flexible joint 218 which permits the surfaces tobe angularly deflected.
It should be readily apparent that the amount of deflection of the mandrel or inner surface determines the amplitude of the applied vibratory load.Similarly, the frequency of the vibration is determined by the speed of rotationof the drive shaft. By controlling the frequency and amplitude of the applied vibratory load, it is possible to control the rheological properties of the moldable material.
Referring now to Figure 16, an embodiment of the present invention is illustrated wherein reinforcing fibers are fed into the moldable material prior to mixing. As discussed above, the prior art devices add reinforcing fibers either when the material is in the hopper or while the material is conveying through the extruder. In Figure 16, a fiber feeding assembly 400 8110-55 2 1 ~S~3~
\57596 is shown which feeds reinforcing fibers directly into the melt prior to mixing and after conveyance by the extruder. The fiber feeding assembly 400 includes a conveyor 402 mounted between the extruder port 28 and the mold housing 14.
The conveyor 402 translates in a direction (as shown by the arrow) which is at S an angle to the material flow so as to locate at least a portion of the conveyor 402 within the material flow. Preferably the direction of travel of the conveyor402 is about 90 to the direction of flow. The conveyor 402 can be translated in a reciprocating manner or, alternately, may be a unidirectional feed. In the latter case, the conveyor 402 may be supplied in the form of a large spool or, 10 more preferably, may be a continuous belt. A power source (not shown) may be used to control the travel of the conveyor 402. The speed of the conveyor 402 may be controlled so as to be proportional to the extruder motor and/or anticipated speed of the material flow.
As shown in the figure, the conveyor 402 has a plurality of open cells 404 formed through it. The open cells 404 are oriented so as to permit themolten material to flow therethrough when the conveyor 402 is placed within the flow. Short or chopped fibers 406 are deposited within the open cells 404.
A vacuum source 407 is preferably utilized to draw the chopped fibers into the open cells. Once the cells 404 are filled with the fibers 406, the conveyor 402 is translated so as to placed the filled cells 404 within the material flow.
Accordingly, as the molten material passes through the open cells 404 it picks up the loose fibers 406. The combination of the molten material and the fibers then enters into the mold housing 14 wherein the fibers are thoroughly mixed with the molten material.
In one preferred embodiment, the conveyor 402 is a continuous screen changer. Continuous screen changers are used in molding devices to filter out cont~min~nt~ from the molten material as it flows through the screen.One suitable type of continuous screen changer is produced by High Technology Corp., Hackensack, New Jersey. The present invention uses the continuous \57596 ~ 5~34 screen changer to incorporate the reinforcing fibers 406 into the melt while at the same time removing any cont~min~nt~ in the flow.
In an alternate configuration shown in Figure 17, the fiber feeding assembly is designed to incorporate long reinforcing fibers into the S material flow. A conveyor 410 is again mounted between the extruder port 28 and the mold housing 14. The conveyor 410 travels in a direction, as shown by the arrow, which is preferably at an angle to the material flow. As with the configuration discussed above, the conveyor 410 is preferably a continuous screen changer for filtering cont~min~tçs out of the material flow. Long reinforcing fibers 412 are positioned on the downstream side of the conveyor 410 prior to placement within the material flow. Accordingly, when the conveyor 402 is translated through the material flow, the reinforcing fibers 412are picked off the conveyor 410 by the flow of material and carried along into the mold housing for further mixing. One method for attaching the fibers 412 to the conveyor 410 is through the use of a vacuum source 414. The vacuum source 414 draws the fibers 412 against the downstream surface of the conveyor 410. Alternate methods for feeding the reinforcing fibers into the material flowmay be substituted for the disclosed embodiments and are well within the purview of the claims.
Although the invention has been described and illustrated with respect to the exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.
Claims (48)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A molding apparatus for applying shear and compressive loads to a flow of moldable material, the apparatus comprising:
a mold housing;
a feeder for supplying a flow of moldable material into the mold housing;
a first boundary element attached to the mold housing and having a first surface which defines a first side of the flow of moldable material;
a second boundary element attached to the mold housing and having a first surface which defines a second side of the flow of moldable material;
a driver in driving contact with a second surface of the first boundary element for deflecting the first boundary element in a direction substantially perpendicular to the flow of moldable material so as to produce relative movement between the first and second boundary elements, the relative movement between the first and second boundary elements subjecting the material therebetween to at least one of a compression force and a shear force;
and a flexible joint within the mold housing and attached to at least the first boundary element to permit the deflection of the first boundary element.
a mold housing;
a feeder for supplying a flow of moldable material into the mold housing;
a first boundary element attached to the mold housing and having a first surface which defines a first side of the flow of moldable material;
a second boundary element attached to the mold housing and having a first surface which defines a second side of the flow of moldable material;
a driver in driving contact with a second surface of the first boundary element for deflecting the first boundary element in a direction substantially perpendicular to the flow of moldable material so as to produce relative movement between the first and second boundary elements, the relative movement between the first and second boundary elements subjecting the material therebetween to at least one of a compression force and a shear force;
and a flexible joint within the mold housing and attached to at least the first boundary element to permit the deflection of the first boundary element.
2. A molding apparatus according to claim 1 further comprising a drive shaft having a longitudinal axis of rotation, the drive shaft being located within the mold housing adjacent to the second surface of the first boundary element and connected to the driver, a power unit for rotating the drive shaft about its longitudinal axis of rotation, and wherein the rotation of the drive shaft deflects the first boundary element so as to produce the relative movement between the first and second boundary elements.
3. A molding apparatus according to claim 2 wherein the driver comprises:
an eccentric portion on the drive shaft having a centerline which is eccentric to the longitudinal axis of rotation of the drive shaft, and a bearing having an inner race and an outer race, the inner race of the bearing journal being located about the eccentric portion, the outer raceof the bearing journal being located adjacent to the second surface of the firstboundary element, the bearing permitting the eccentric portion to rotate with respect to the first boundary element.
an eccentric portion on the drive shaft having a centerline which is eccentric to the longitudinal axis of rotation of the drive shaft, and a bearing having an inner race and an outer race, the inner race of the bearing journal being located about the eccentric portion, the outer raceof the bearing journal being located adjacent to the second surface of the firstboundary element, the bearing permitting the eccentric portion to rotate with respect to the first boundary element.
4. A molding apparatus according to claim 3 wherein the driver further comprises a bearing journal located between the inner race of the bearing and the eccentric portion, the combination of the bearing journal and the eccentric portion defining a driver centerline, the amount of deflection of the first boundary element being a function of the distance between the driver centerline and the longitudinal axis of rotation of the shaft.
5. A molding apparatus according to claim 4 wherein the bearing journal has an eccentric shape and is rotatable about the eccentric portion so as to vary the distance between the driver centerline and the longitudinal axis of rotation of the shaft.
6. A molding apparatus according to claim 5 wherein the distance between the driver centerline and the longitudinal axis varies between about zero inches and about 0.125 inches.
7. A molding apparatus according to claim 5 further including a locking mechanism for locking the bearing journal to the eccentric portion.
8. A molding apparatus according to claim 3 wherein the eccentric portion is formed integral with the drive shaft.
9. A molding apparatus according to claim 1 wherein the first boundary element is a cylindrical mandrel and wherein the second mold surface is a cylindrical die mold.
10. A molding apparatus according to claim 9 wherein the cylindrical mandrel is rotated with respect to the die mold.
11. A molding apparatus according to claim 10 wherein the cylindrical mandrel is rotated in an opposite direction than the direction of rotation of the drive shaft.
12. A molding apparatus according to claim 9 wherein the flexible joint comprises a cylindrical bellows which permits the cylindrical mandrel to be deflected in a direction perpendicular to the flow of moldable material, and wherein the cylindrical bellows is threadingly attached to the mandrel.
13. A molding apparatus according to claim 12 further including a spindle for attaching the flexible joint to the mold housing.
14. A molding apparatus according to claim 1 wherein the flexible joint comprises a bellows which permits the first mold surface to be deflected in a direction perpendicular to the flow of moldable material.
15. A molding apparatus according to claim 1 further including at least one conveyor flight located between the first and second boundary elements, the conveyor flight conveying the moldable material between the first and second boundary elements.
16. A molding apparatus according to claim 15 wherein the conveyor flight is attached to the first boundary element.
17. A molding apparatus according to claim 15 wherein the conveyor flight is attached to the second boundary element.
18. A molding apparatus according to claim 1 further including at least one flow separator located between the first and second boundary elements, the flow separator assisting in the mixing of the moldable material.
19. A molding apparatus according to claim 18 wherein the flow separator is attached to the first side of the first boundary element.
20. A molding apparatus according to claim 18 wherein the flow separator is attached to the first side of the second boundary element.
21. A molding apparatus according to claim 1 further comprising a blow mold located downstream from the drive, the blow mold receiving the flow of moldable material and having a mold surface defining the shape of the final product, and a pressure source in fluidic communication with the blow mold for supplying a pressurized medium into the blow mold to expand the moldable material onto the mold surface.
22. A molding apparatus according to claim 2 wherein the drive shaft extends through the feeder and has at least one flight of conveyors formedon it for compressing and conveying the moldable material from a hopper to the first and second boundary elements.
23. A molding apparatus according to claim 1 wherein the first and second boundary elements are substantially parallel to one another and define the lower and upper surfaces of a die mold for flat sheet material.
24. A molding apparatus according to claim 23 wherein the driver includes a linear actuator for driving the first boundary element perpendicular to the flow of moldable material.
25. A molding apparatus according to claim 1 further including a controller for controlling the frequency of deflection of the first boundary element by the driver.
26. A molding apparatus for applying shear and compressive loads to a flow of moldable during the formation of a tube in a die molding process, the apparatus comprising:
a mold housing;
a mandrel attached to the mold housing and having an outer wall which defines an inner surface of a tube, the mandrel also having an inner wall which defines an interior cavity;
a mold die attached to the mold housing and having an inner wall which defines an outer surface of the tube;
a feeder for supplying a flow of moldable material into the mold housing and between the mandrel and the mold die, the feeder including a hopper for providing a moldable material, a heater for melting the moldable material and an extruder screw for compressing and conveying the melted moldable material;
a drive shaft positioned within the interior cavity of the mandrel and having an axis of rotation, the drive shaft including an eccentric portion;
a bearing positioned between the eccentric portion and the inner wall of the mandrel, the bearing permitting rotation of the eccentric portion with respect to the mandrel;
a power unit for rotating the drive shaft about its axis of rotation;
wherein the eccentric portion of the drive shaft deflects the mandrel in a direction perpendicular to the flow of moldable material when the drive shaft is rotated; and a flexible joint attached to the mold housing and to the mandrel so as to permit the deflection of the mandrel.
a mold housing;
a mandrel attached to the mold housing and having an outer wall which defines an inner surface of a tube, the mandrel also having an inner wall which defines an interior cavity;
a mold die attached to the mold housing and having an inner wall which defines an outer surface of the tube;
a feeder for supplying a flow of moldable material into the mold housing and between the mandrel and the mold die, the feeder including a hopper for providing a moldable material, a heater for melting the moldable material and an extruder screw for compressing and conveying the melted moldable material;
a drive shaft positioned within the interior cavity of the mandrel and having an axis of rotation, the drive shaft including an eccentric portion;
a bearing positioned between the eccentric portion and the inner wall of the mandrel, the bearing permitting rotation of the eccentric portion with respect to the mandrel;
a power unit for rotating the drive shaft about its axis of rotation;
wherein the eccentric portion of the drive shaft deflects the mandrel in a direction perpendicular to the flow of moldable material when the drive shaft is rotated; and a flexible joint attached to the mold housing and to the mandrel so as to permit the deflection of the mandrel.
27. A molding apparatus according to claim 26 further comprising a bearing journal located between the eccentric portion and the bearing, the bearing journal having an inner side and an outer side, the inner side of the bearing journal being disposed about and in contact with the eccentric portion, the outer side of the bearing journal being attached to an inner race of the bearing, the outer side of the bearing journal defining a shape which is non-concentric with the inner side of the bearing journal, and wherein the combination of the bearing journal and the eccentric portion define a driver centerline, rotation of the bearing journal varying the distance between the driver centerline and the longitudinal axis of rotation of the shaft, the amountof deflection of the mandrel being a function of the distance between the drivercenterline and the longitudinal axis of rotation of the shaft.
28. A molding apparatus according to claim 27 further comprising a locking mechanism for locking the bearing journal to the eccentric portion.
29. A molding apparatus according to claim 27 wherein rotation of the bearing journal varies the distance between the driver centerline and thelongitudinal axis from between about zero inches and about 0.125 inches.
30. A molding apparatus for applying shear and compressive loads to a flow of moldable material, the apparatus comprising:
a mold housing;
a feeder for supplying a flow of moldable material into the mold housing;
a first boundary element attached to the mold housing and having a first surface which defines a first side of the flow of moldable material;
a second boundary element attached to the mold housing and having a first surface which defines a second side of the flow of moldable material; and a motor for displacing the a portion of the first boundary element in a direction substantially perpendicular to the flow of moldable material so as to produce relative movement between the first and second boundary elements, the relative movement between the first and second boundary elements subjecting the material therebetween to at least one of a compression force and a shear force.
a mold housing;
a feeder for supplying a flow of moldable material into the mold housing;
a first boundary element attached to the mold housing and having a first surface which defines a first side of the flow of moldable material;
a second boundary element attached to the mold housing and having a first surface which defines a second side of the flow of moldable material; and a motor for displacing the a portion of the first boundary element in a direction substantially perpendicular to the flow of moldable material so as to produce relative movement between the first and second boundary elements, the relative movement between the first and second boundary elements subjecting the material therebetween to at least one of a compression force and a shear force.
31. A molding apparatus according to claim 30 wherein the first boundary element is a mandrel and wherein the second boundary element is a circular die mold, wherein the mandrel is non-concentric with the die mold and where the motor rotates the mandrel with respect to the die mold to produce the displacement of the mandrel perpendicular to the flow of moldable material.
32. A molding apparatus according to claim 30 wherein the first and second boundary elements are substantially flat and parallel to one another.
33. A molding system for applying compressive and shear loads to a flow of moldable material comprising the steps of:
combining a first material component and a second material component so as to produce a mixture;
melting the mixture of first and second material components so as to form a flow of moldable material;
conveying the flow of moldable material between first and second boundary elements of a molding apparatus;
deflecting a portion of the first boundary element in a direction substantially perpendicular to the flow of moldable material, the deflection of the first boundary element imposing at least one of a shear load and a compressive load on the flow of moldable material which produce further mixing of the moldable material; and curing the flow of moldable material into a final product.
combining a first material component and a second material component so as to produce a mixture;
melting the mixture of first and second material components so as to form a flow of moldable material;
conveying the flow of moldable material between first and second boundary elements of a molding apparatus;
deflecting a portion of the first boundary element in a direction substantially perpendicular to the flow of moldable material, the deflection of the first boundary element imposing at least one of a shear load and a compressive load on the flow of moldable material which produce further mixing of the moldable material; and curing the flow of moldable material into a final product.
34. A molding system according to claim 33 further comprising the steps of:
delivering the flow of moldable material to a blow mold after deflecting of the first boundary element, the blow mold having a mold contour which defines the shape of the final product; and blowing the moldable material onto the mold contour.
delivering the flow of moldable material to a blow mold after deflecting of the first boundary element, the blow mold having a mold contour which defines the shape of the final product; and blowing the moldable material onto the mold contour.
35. A molding system according to claim 33 further comprising the step of biasing a portion of the first boundary element during deflection ofthe first boundary element.
36. A molding system for applying compressive and shear loads to a flow of moldable material comprising the steps of:
combining a first material component and a second material component so as to produce a mixture;
melting the mixture of first and second material components so as to form a flow of moldable material;
conveying the flow of moldable material between an outer mold die and an inner mandrel;
rotating a drive shaft located within the inner mandrel, the drive shaft having an eccentric portion which is engaged with the inner mandrel;
deflecting a portion of the inner mandrel by the rotation of the eccentric portion, the deflection being in a direction substantially perpendicular to the flow of moldable material, the deflection imposing at least one of a shear load and a compressive load onto the flow of moldable material so as to further mix the moldable material;
flexing a portion of the inner mandrel when the inner mandrel is deflected by the eccentric portion; and curing the flow of the moldable material into a final product after deflection of the mandrel.
combining a first material component and a second material component so as to produce a mixture;
melting the mixture of first and second material components so as to form a flow of moldable material;
conveying the flow of moldable material between an outer mold die and an inner mandrel;
rotating a drive shaft located within the inner mandrel, the drive shaft having an eccentric portion which is engaged with the inner mandrel;
deflecting a portion of the inner mandrel by the rotation of the eccentric portion, the deflection being in a direction substantially perpendicular to the flow of moldable material, the deflection imposing at least one of a shear load and a compressive load onto the flow of moldable material so as to further mix the moldable material;
flexing a portion of the inner mandrel when the inner mandrel is deflected by the eccentric portion; and curing the flow of the moldable material into a final product after deflection of the mandrel.
37. A molding system according to claim 36 further comprising the steps of:
adjusting the deflection of the inner mandrel by rotating a bearing journal with respect to a bearing; and locking the bearing journal into engagement with the eccentric portion so as to maintain the adjusted deflection.
adjusting the deflection of the inner mandrel by rotating a bearing journal with respect to a bearing; and locking the bearing journal into engagement with the eccentric portion so as to maintain the adjusted deflection.
38. A molding system according to claim 36 further comprising the step of rotating at least a portion of the mandrel.
39. A molding system according to claim 38 wherein the mandrel is rotated in an oscillatory manner.
40. A molding system according to claim 38 wherein the mandrel is rotated in a direction opposite to the direction of rotation of the drive shaft.
41. A molding system according to claim 38 wherein the mandrel has two portions which are rotated in opposite directions with respect to one another.
42. A molding system according to claim 33 further comprising the step of supplying at least one reinforcing fiber into the flow of moldable material prior to conveyance between the first and second boundary elements.
43. A molding system according to claim 42 wherein the step of supplying the reinforcing fiber includes placing the reinforcing fiber in contact with a conveyor and translating the conveyor and reinforcing fiber into the flowof moldable material.
44. A molding system according to claim 36 further comprising the step of supplying at least one reinforcing fiber into the flow of moldable material prior to conveyance between the outer mold die and the inner mandrel.
45. A molding system according to claim 44 wherein the step of supplying the reinforcing fiber includes placing the reinforcing fiber in contact with a conveyor and translating the conveyor and reinforcing fiber into the flowof moldable material.
46. A molding apparatus according to claim 1 wherein the feeder includes an extruder screw for conveying the flow of moldable material, the apparatus further comprising:
a conveyor located between the extruder screw and the mold housing, the conveyor being translatable in a direction at an angle to the direction of the material flow and having a plurality of open cells formed on it, the open cells configured to permit the passage of the moldable material when the conveyor is translated into the flow of moldable material; and means for depositing at least one reinforcing fiber in contact with the conveyor, the reinforcing fiber intermixing with the flow of moldable material when the conveyor is translated into the flow of moldable material.
a conveyor located between the extruder screw and the mold housing, the conveyor being translatable in a direction at an angle to the direction of the material flow and having a plurality of open cells formed on it, the open cells configured to permit the passage of the moldable material when the conveyor is translated into the flow of moldable material; and means for depositing at least one reinforcing fiber in contact with the conveyor, the reinforcing fiber intermixing with the flow of moldable material when the conveyor is translated into the flow of moldable material.
47. A molding apparatus according to claim 26 the apparatus further comprising:
a conveyor located between the extruder screw and the mold housing, the conveyor being translatable in a direction at an angle to the direction of the material flow and having a plurality of open cells formed on it, the open cells configured to permit the passage of the moldable material when the conveyor is translated into the flow of moldable material; and a vacuum for drawing at least one reinforcing fiber into contact with the conveyor, the reinforcing fiber intermixing with the flow of moldable material when the conveyor is translated into the flow of moldable material.
a conveyor located between the extruder screw and the mold housing, the conveyor being translatable in a direction at an angle to the direction of the material flow and having a plurality of open cells formed on it, the open cells configured to permit the passage of the moldable material when the conveyor is translated into the flow of moldable material; and a vacuum for drawing at least one reinforcing fiber into contact with the conveyor, the reinforcing fiber intermixing with the flow of moldable material when the conveyor is translated into the flow of moldable material.
48. A molding apparatus according to claim 30 wherein the feeder includes an extruder screw for conveying the flow of moldable material, the apparatus further comprising:
a conveyor located between the extruder screw and the mold housing, the conveyor being translatable in a direction at an angle to the direction of the material flow and having a plurality of open cells formed on it, the open cells configured to permit the passage of the moldable material when the conveyor is translated into the flow of moldable material; and means for depositing at least one reinforcing fiber in contact with the conveyor, the reinforcing fiber intermixing with the flow of moldable material when the conveyor is translated into the flow of moldable material.
a conveyor located between the extruder screw and the mold housing, the conveyor being translatable in a direction at an angle to the direction of the material flow and having a plurality of open cells formed on it, the open cells configured to permit the passage of the moldable material when the conveyor is translated into the flow of moldable material; and means for depositing at least one reinforcing fiber in contact with the conveyor, the reinforcing fiber intermixing with the flow of moldable material when the conveyor is translated into the flow of moldable material.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52647595A | 1995-09-08 | 1995-09-08 | |
| US08/526,475 | 1995-09-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2185034A1 true CA2185034A1 (en) | 1997-03-09 |
Family
ID=24097510
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002185034A Abandoned CA2185034A1 (en) | 1995-09-08 | 1996-09-06 | Molding material under the application of shear, compressive and/or tensile loads |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2185034A1 (en) |
-
1996
- 1996-09-06 CA CA002185034A patent/CA2185034A1/en not_active Abandoned
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| FZDE | Dead |
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