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WO1996019330A1 - Transformation des caracteristiques physiques d'un materiau moulable - Google Patents

Transformation des caracteristiques physiques d'un materiau moulable Download PDF

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Publication number
WO1996019330A1
WO1996019330A1 PCT/US1994/014605 US9414605W WO9619330A1 WO 1996019330 A1 WO1996019330 A1 WO 1996019330A1 US 9414605 W US9414605 W US 9414605W WO 9619330 A1 WO9619330 A1 WO 9619330A1
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WO
WIPO (PCT)
Prior art keywords
drivable
mold
moldable material
reciprocating
process according
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.)
Ceased
Application number
PCT/US1994/014605
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English (en)
Inventor
Jean-Pierre Ibar
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thermold Partners LP
Original Assignee
Thermold Partners LP
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Thermold Partners LP filed Critical Thermold Partners LP
Priority to AU15528/95A priority Critical patent/AU1552895A/en
Priority to PCT/US1994/014605 priority patent/WO1996019330A1/fr
Publication of WO1996019330A1 publication Critical patent/WO1996019330A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0082—Reciprocating the moulding material inside the mould cavity, e.g. push-pull injection moulding

Definitions

  • This invention relates to a means for transforming the physical characteristics of a moldable material during a molding process.
  • the present invention relates to molding processes wherein a stress tensor is exerted onto a moldable material prior to, and in the course of, it solidifying.
  • the invention therein relates, at least in part, to a process and apparatus which mod ⁇ ifies the morphological structure of a molded material by varying temperatures during- the molding process simultaneously with at least one other rheological parameter such as hydrostatic pressure, shear stress, mechanical vibration (frequency or amplitude), dielectric vibration (frequency or amplitude) for dielectric materials and electromagnetic properties for metallic materials.
  • at least one other rheological parameter such as hydrostatic pressure, shear stress, mechanical vibration (frequency or amplitude), dielectric vibration (frequency or amplitude) for dielectric materials and electromagnetic properties for metallic materials.
  • Patent 5,074,772 each of which relates to a process which modifies the morphological structure of a molded material by varying temperatures during the molding process simultaneously with shear stress.
  • U.S. Patent 4,469,649 and the other aforementioned patents is that the latter group of patents disclose specific methods in which to apply a shear stress.
  • the molding industry is constantly looking for different ways in which to control the morphological structure and/or physical properties of a moldable material prior to and/or during the molding process. This need has prompted the discovery of the molding processes disclosed herein.
  • One object of this invention is to provide a means for transforming the physical characteristics of a moldable material during a molding process.
  • Another object of this invention is to provide a molding processes wherein a stress tensor is exerted onto a moldable material prior to, and in the course of, it solidifying.
  • Yet another object of this invention is to provide a molding process which controls certain fabrication variables prior to and/or during the molding process in order to modify the end-use performance of the finished product.
  • a moldable material is supplied into a mold until said mold's cavity is filled. Then, at each of at least two spaced-apart regions of the moldable material, a reciprocating device is provided.
  • Each reciprocating device is in communication with the moldable material. Moreover, each reciprocating device includes a drivable member reciprocable within, and relative to, a chamber.
  • the reciprocating devices are designed to manipulate the moldable material by exerting a stress tensor thereon prior to, and in the course of, it solidifying within the mold's cavity.
  • This manipulation is created by recipro- eating the drivable member of each reciprocating device, with respect to another drivable member, in a manner selected from the group consisting of: (a) at the same frequency, at a different amplitude and out of phase, (b) at the same fre ⁇ quency, at a different amplitude and in phase, (c) at a different frequency and at the same amplitude, and (d) at a different frequency and at a different amplitude.
  • the frequency, amplitude and/or phase shift of the drivable members can be constant, variable and/or intermittent.
  • the temperature of the mold can be increased and/or decreased prior to, and in the course of, the material contained therein solidifying. This allows the monitoring of the cooling rate during the cooling of the moldable material to change. It also allows the internal temperature of the mold to be set at the time of feeding the moldable material therein.
  • the morphological structure of the resulting solid product e.g., percentage crystallinity, orientation, free volume content, texture, etc.
  • the physical properties depend e.g., tensile strength, tensile modulus, etc.
  • FIGURE 1 represents a schematic illustration of a conventional injection molding apparatus and mold.
  • FIGURES 2 to 4, inclusive, illustrate schematic illustrations of a manifold including one embodiment of a reciprocation means interposed between an injection molding apparatus and a mold in accordance with the present invention.
  • FIGURE 5 is a detailed illustration of the manifold illustrated in Figures 2 to 4, inclusive.
  • FIGURE 6 is a cross-sectional side elevation of the manifold illustrated in Figure 5 taken along line 6-6.
  • FIGURE 7 is a general schematic of one embodiment of the invention illustrating a system designed to control a reciprocation pattern in accordance with the present invention.
  • FIGURE 8 represents a schematic illustration of an injection molding apparatus which can be used when practicing the present invention.
  • FIGURE 9 represents a schematic illustration of a portion of a hot-runner molding system which can be used when practicing the present invention.
  • FIGURE 10 is a front view of the portion of the hot-runner molding system illustrated in Figure 9.
  • FIGURE 11 represents a schematic illustration of a portion of a cold-runner molding system which can be used when practicing the invention.
  • FIGURE 12 is a front view of the portion of the cold-runner molding system illustrated in Figure 11.
  • FIGURE 13 represents a schematic illustration of a portion of a cold-runner molding system which can be used when practicing the present invention, and which employs more than two reciprocating drivable members.
  • FIGURE 14 is a front view of the portion of the cold-runner molding system illustrated in Figure 13.
  • FIGURE 15 is a graph which illustrates the action of two drivable members acting at different frequencies and amplitudes on a melt.
  • frequency refers to the number of times a particular drivable member oscillates per second.
  • amplitude refers to the maximum longitudinal distance traveled by a drivable member during half of an oscillation cycle.
  • phase refers to the relative motion of one drivable member with respect to another which is oscillating at the same frequency.
  • stress tensor refers to a matrix which comprises two essential components — a compressive force and a shear stress.
  • the present invention relates to a process for molding a solid product from a moldable material.
  • a moldable material is supplied into a mold.
  • the mold is designed in such a manner that, at each of at least two spaced-apart regions of the moldable material, there is a reciprocating device.
  • Each reciprocating device includes a drivable member which is reciprocable within, and relative to, a chamber. These reciprocating devices are designed to manipulate the moldable material prior to, and in the course of, its solidifying within the mold's cavity by exerting a stress tensor on the moldable material.
  • This manipulation is created by reciprocating the drivable members of each reciprocating device, with respect to one another, in a specific manner.
  • the reciprocating devices of the present invention generally include a drivable member which is reciprocable within, and relative to, a chamber.
  • This chamber is designed to be in direct or indirect communication with the moldable material, when the material is confined within the mold's cavity.
  • the drivable members and their respective chambers can have any configuration which enables one to practice this invention.
  • suitable drivable members include, without limitation, oscillating pistons (see, e.g., Figure 2), oscillating injection screws (see, e.g., Figure 3) and the like, and/or any combination thereof.
  • oscillating pistons see, e.g., Figure 2
  • oscillating injection screws see, e.g., Figure 3
  • these reciprocating devices must be at spaced-apart regions of the mold's cavity.
  • the material can, optionally, be packed into the mold.
  • the reciprocating devices are employed to manipulate the moldable material in accordance with the present invention. This manipulation is per ⁇ formed prior to, and in the course of, the moldable material solidifying within the mold.
  • the moldable material is reciprocated in accordance with a specific pattern, it is within the purview of this invention to, optionally, exert a packing pressure thereon.
  • the manipulation of the moldable material is performed by reciprocating the drivable member of each reciprocating device, with respect to any other drivable member, in one of four different manners. These are as follows: (a) at the same frequency, at a differ- ent amplitude and out of phase, (b) at the same frequency, at a different amplitude and in phase, (c) at a different frequency and at the same amplitude, and (d) at a different frequency and at a different amplitude.
  • the frequency, amplitude and/or phase shift of the drivable members can remain constant, be variable and/or be intermittent throughout the molding process. If the mode of manipulating the moldable material varies, the drivable members must still operate in one of the aforementioned manners.
  • the various drivable members can be reciprocated at any suitable frequency.
  • the preferred frequency will depend, at least in part, upon the size of the drivable members, the number of recipro ⁇ cating means, the amplitude of the drivable members, the location of the drivable members, and the like, as well as the desired effects on the resulting product. Those skilled in the art, after reading this specification, will be able to determine the optimum frequency which best suits their specific needs.
  • the frequency ( ) at which the various drivable members are reciprocated typically ranges from between about 1 to about 120 Hz.
  • the drivable members are reciprocated at a frequency rang ⁇ ing from between about 1 to about 100 Hz, and more preferably, from between about 1 to about 80 Hz.
  • one drivable member is reciprocated at a frequency of (fi) and at least one other drivable member is reciprocated at a frequency of (f 2 ).
  • Frequencies (fj) and (f 2 ) each can range from about 1 to about 120 Hz.
  • frequencies (f ⁇ ) and (f 2 ) are the same, the drivable members must operate at a different amplitude.
  • frequencies (f ⁇ ) and (f 2 ) are different, the drivable members can operate at the same or at a different amplitude.
  • the various drivable members can be reciprocated at any suitable amplitude.
  • the preferred amplitude will depend, at least in part, upon the size of the drivable members, the number of recipro ⁇ cating means, the frequency of the drivable members, the location of the drivable members, and the like, as well as the desired effects on the resulting product. Those skilled in the art, after reading this specification, will be able to determine the optimum amplitude which best suits their specific needs.
  • the amplitude (a) at which the various drivable members are reciprocated is such that they generate a compressive force within the mold ranging from between about 100 to about 20,000 psi.
  • the drivable members are reciprocated at an amplitude such that they generate a compressive force within the mold ranging from between about 100 to about 15,000 psi, and more preferably, from between about 100 to about 10,000 psi.
  • one drivable member is reciprocated at an amplitude of (a,) and at least one other drivable member is reciprocated at an amplitude of (a 2 ).
  • Amplitudes (a t ) and (a 2 ) are such that they generate a compressive force within the mold ranging from between about 100 to about 10,000 psi.
  • amplitudes (a,) and (a 2 ) When amplitudes (a,) and (a 2 ) are the same, the drivable members must operate at a different frequency. On the other hand, when amplitudes (a,) and (a 2 ) are different, the drivable members can operate at the same or at a different frequency.
  • Patent 4,952,161 it has been discovered that the morphological structure of the resulting solid product (e.g., percentage crystallinity, orientation, free volume content, texture, etc.), from which the physical properties depend (e.g., tensile strength, tensile modulus, etc.), can be modified by reciprocating the drivable members in a manner which not only creates a shear stress, on the moldable material, but also simultaneously generates a compressive force thereon. As indicated above, manipulating a moldable material in such a manner is referred to herein as ex ⁇ erting a stress tensor thereon.
  • One of the objects of this invention is to exert a specific stress tensor by separately monitoring and controlling the stress tensor's individual components (i.e., shear stress and compressive force).
  • the shear stress compo ⁇ nent affects the orientation of the moldable material, where as the compressive force component affects the material's temperature.
  • drivable members when at least two drivable members are reciprocated at the same frequency, they can be recipro- cated either "in phase” or “out of phase” with each other.
  • the phase shift between two such drivable members can range from 0 to 6.28 radians.
  • the drivable members When the phase shift is at the values of 0 or 6.28 radians, the drivable members are oscillating in phase with each other. On the other hand, when the phase shift is at an amount ranging from between a value slightly greater than about 0 radians to a value slightly less than 6.28 radians, the drivable members are oscillating out of phase with each other.
  • the various drivable members which are reciprocated at the same frequency can be oscillated at any suitable phase shift, or at none at all (i.e., in phase).
  • the preferred phase shift will depend, at least in part, upon the size of the drivable members, the number of reciprocating means, the amplitude of the drivable members, the frequency of the drivable members, the location of the drivable members, and the like, as well as the desired effects on the resulting product.
  • Those skilled in the art after reading this specification, will be able to determine the optimum phase shift which best suits their specific needs.
  • the phase shift therebetween typically ranges from between about 0.79 to about 5.50 radians.
  • the drivable members are reciprocated at a phase shift ranging from between about 1.57 to about4.71 radians, and more preferably, from between about 2.36 to about 3.93.
  • the stress tensor is exerted on the moldable material by reciprocating the drivable members of each reciprocating device, with respect to another drivable member, in one of four different manners. While the stress tensor is being exerted in accordance with this invention, the frequency, amplitude and/or phase shift of the individual drivable members can be constant, varied and/or intermittent throughout the molding process.
  • a specific frequency, amplitude and phase shift that two or more drivable members will reciprocate with respect to one another is selected.
  • the selected parameters must fall within one of the aforementioned manners of exerting a stress tensor on a moldable material. These settings are referred to herein as a specific "reciprocation pattern".
  • a reciprocation pattern can be designed to remain constant throughout the molding process.
  • this reciprocation pattern it is also within the purview of this invention to have this reciprocation pattern vary and/or be intermittent throughout the molding process.
  • the reciprocation pattern varies during a molding process, the drivable members must always operate, with respect to one another, in one of the four aforementioned manners.
  • the frequency, amplitude and/or phase shift of at least one drivable member can vary, for example, from a low value to a high value, or vice versa. This variation can occur linearly, exponen ⁇ tially, randomly and/or intermittently.
  • the variance of one drivable member can be either the same or different from that of another drivable member.
  • a varying reciprocation pattern in accordance with the present invention can result from the parameters of only one drivable member varying while those of all other drivable members remain the same, the parameters of at least two drivable members varying in the same manner, and/or the parameters of at least two drivable members varying in different manners.
  • subsequent materials are prepared in accordance with the present invention wherein one of the stress exertion parameters (e.g., frequency, amplitude and/or phase shift) is changed.
  • one of the stress exertion parameters e.g., frequency, amplitude and/or phase shift
  • a skilled artisan can see how the variance of a specific stress exertion parameter affects the particular material ' s morphological structure . This information can then be used to determine how the stress exertion parameters must be modified in order to produce a product having the desired morphological structure and/or physical properties. Once the parameters have been established, the results can be easily reproduced by using the same reciprocation pattern under similar circumstances.
  • thermal analysis instruments such as a Differential Scanning Calorimeter (DSC) and/or a Thermal Stimulated Current/Relaxation Map Analysis (TSC/RMA) spectrometer
  • DSC Differential Scanning Calorimeter
  • TSC/RMA Thermal Stimulated Current/Relaxation Map Analysis
  • skilled artisans should note a significant difference in the specific heat traces during heating at rate of 10°C per minute which is characteristic of morphological changes occurring during the molding process.
  • skilled artisans should also note a significant difference in the relative positions of the melting temperature, glass transition temperature and secondary transitions, as shown in the TSC/RMA peaks.
  • each drivable member can be programmed in the following manner:
  • Bj Ao -I- A, sin (fit + b,)
  • B 2 A' 0 + A sin (f x x + b'j)
  • B is the phase of one drivable member and B 2 is the phase of another drivable member
  • a ⁇ t), A' 0 (t), A,(t), A',(t), /,(-), /,(t), b,(t) and b',(t) are functions of time.
  • the variables which can be inserted into these equations are selected such that the resulting reciprocation pattern will induce changes in the thermal history of the final product throughout the interaction between the propagation of the pressure/shear waves induced by the drivable member through the visco-elastic medium represented by the moldable material during the molding process.
  • the frequency of a particular drivable member is twice that of another drivable member. Moreover, the amplitude of the higher frequency drivable member is smaller but varies faster than that of the other drivable member.
  • the amplitude average may vary exponentially in a preferred embodiment with the inverse of absolute temperature in the following manner to account for viscosity changes in the plastic:
  • Any suitable means can be employed to reciprocate the drivable members.
  • suitable means include, without limitation, hydraulic devices, pneumatic devices, mechanical devices, electrical devices, electromag ⁇ netic devices and any combination thereof.
  • the preferred method of reciprocating the drivable members will depend, in part, upon the resources available to the person practicing this invention and the type of drivable member selected.
  • the stress tensor exerted upon the moldable material by the reciprocating means can occur for any suitable period of time.
  • the preferred period of time will depend, in part, upon the size of the drivable members, the number of reciprocating means, the amplitude of the drivable members, the frequency of the drivable members, the location of the drivable members, and the like, as well as the desired effects on the resulting product. Those skilled in the art, after reading this specification, will be able to determine the optimum time period over which to exert the stress tensor which suits their specific needs.
  • the manner in which the stress tensor is applied to the moldable material is established by a predetermined program.
  • a specific reciprocation pattern is determined prior to manipulating the moldable material in accordance with the present invention. This would include not only determining specific starting frequencies, amplitudes, phase shift parameters and time parameters, but also determining whether these initial settings will vary and be intermittent during the molding process, determining at what temperatures certain modifications occur when varying parameters such as Ao(t), A' 0 (t), A ⁇ t),
  • a suitable temperature sensing device e.g., an infrared temperature sensing device
  • the packing force exerting onto the moldable material after, and optionally prior to and/or during, the reciprocation pattern can be applied by any suitable means known to those skilled in the art.
  • the packing force can be applied by a packing device (e.g., an extrusion screw, a piston, etc.), by at least one of the reciprocating means, and/or by any combination thereof.
  • the product is solidified, it is extracted from the mold's cavi- ty.
  • the manner in which the solid product is extracted depends, in part, upon the specific type of mold, molding process and/or molding apparatus.
  • the morphological structure of the resulting solid product (e.g., percentage crystallinity, orientation, free volume content, texture, etc.), from which the physical properties depend (e.g., tensile strength, tensile modulus, etc.), is different from that of a product made from the identical process but which did not employ one of the manipulation techniques disclosed herein. Accordingly, by varying the parameters of the present invention, skilled artisans now have a greater degree of control over the resulting product's structure and/or properties.
  • sensors can be used to monitor certain physical characteristics of the moldable material during the molding process. These sensors can be designed to send information to a data processor. The data processor can be designed to monitor and control the reciprocation pattern during the molding process.
  • the molding process of this invention is suitable for application to a moldable material which comprises a polymer material (e.g., an organic polymer material). Moreover, the process may be applied to thermosettable polymer materials (e.g., those formed in situ by Reactive Injection Molding (RIM) processes).
  • a polymer material e.g., an organic polymer material
  • thermosettable polymer materials e.g., those formed in situ by Reactive Injection Molding (RIM) processes.
  • thermoplastic polymer materi ⁇ als examples include, but are not limited to those which are amorphous, certain polyesters, free radical-polymerized polystyrene, polymers of (meth)acrylate esters and poly(ether-sulphones), those which may be, or become during molding, semicrystalline polymer materials, as well as semi- crystalline polymer material which can be effectively oriented.
  • the molding process of this invention is also particularly suitable for application to polymer material which comprises a liquid crystalline, prefer ⁇ ably a thermotropic liquid crystalline, polymer (e.g., liquid crystalline polyester, preferably a liquid crystalline aromatic polyester).
  • a thermotropic liquid crystalline, polymer e.g., liquid crystalline polyester, preferably a liquid crystalline aromatic polyester.
  • Blends of one or more of thermoplastic polymers, including one or more liquid crystalline polymers, may be molded by the process of this inven ⁇ tion.
  • the moldable material used in the molding process of this invention may comprise a filler (e.g., a fibrous filler such as glass or carbon fiber).
  • Preferred filled molding compositions include glass fiber-filled polypropylene and poly(aryle ⁇ herketone) and, carbon fiber-filled poly(aryletherketone) and nylon.
  • the resulting molded articles can be subjected to controlled heat treatment to convert them into sintered ceramic or metal products.
  • a second, anisotropic, refractory filler e.g., a refractory fibrous filler
  • such products subjected to the process of the present invention will have oriented fibers.
  • the moldable material introduced into the mold should not be too fluid during the varying stress stage.
  • MFI melt flow index
  • the MFI melt flow index
  • the present invention can be used with any molding apparatus wherein a moldable material is introduced into a mold. It is most advantageous when the molding apparatus is an injection molding device or a transfer molding device.
  • FIG. 1 a conventional ("prior art") injection molding machine 10 is illustrated.
  • This machine includes a drivable injection screw 12 mounted for rotation about, and for oscillation along, its axis within a substantially coaxially extending elongate cavity 13 of a cylindrical, heatable barrel 14. Downstream from the screw, the elongate cavity communicates within a nozzle 15 and bushing 16. Upstream from the screw, the elongate cavity com ⁇ municates with a feed hopper 17 containing polymer feedstock 19.
  • Bushing 16 is designed to mate with mold 18. Mold 18 defines cavity 20 which communicates with screw cavity 13 via channel 22.
  • Figures 2-4 illustrate an embodiment of the present invention having two reciprocating devices. These devices are in the form of pistons reciprocable within cylinders.
  • bushing 16 mates with manifold 24 which houses the reciprocating devices.
  • Bushing 16 communicates with an axially-symmetric, bifurcated channel 26, each branch of which leads into cylinders 28 and 30.
  • Mounted in these cylinders are axially-slidable, drivable pistons 32 and 34, respectively.
  • Each of cylinders 28 and 30 communicate downstream with axially aligned twin nozzles 36 and 38, respectively.
  • Nozzles 36 and 38 mate with mold 35.
  • Mold 35 is designed to include a double sprued, double gated bar mold cavity 20.
  • Sprues 40 and 42 communicate with the bushings 46 and 48 of the twin nozzles, respectively.
  • the mold tooling is first assembled.
  • a suitable demolding agent is generally applied to the surfaces defining the mold cavity.
  • the mold is then closed and brought to temperature.
  • Granular polymer feedstock is fed from the feed hopper into the elongate cavity and heated by the cylindrical barrel heater.
  • the molten polymer feedstock is further heated, plasticized, and rendered substantially homogeneous by rotation of the injection screw.
  • the molten polymer feedstock When the molten polymer feedstock is determined to be of the desired viscosity, it is injected into manifold 24, by rotation and downstream translation of the injection screw.
  • the molten polymer feedstock enters manifold 24 via bifurcated channels 26.
  • pistons 32 and 34 When pistons 32 and 34 are positioned in the manner illustrated in Figure 2, the molten polymer feedstock passes, successively, through cylinder 30, nozzle 38, sprue 42, mold cavity 20, sprue 40, nozzle 36 and finally into cylinder 28. Further transport beyond cylinder 28 is prevented by piston 32 blocking channel 26.
  • the injection screw is stopped from rotating.
  • manifold 24 splits the single feed from nozzle 15 into the desired number of separate feeds.
  • the feed has been split into two identical channels.
  • pistons 32 and 34 are reciprocated in accordance with a reciprocation pattern encompassed by the present invention.
  • This specific recip ⁇ rocation pattern exerts a stress tensor on the molten polymer feedstock in the mold cavity, sprues and cylinders. If any shrinkage occurs during the mampulation and/or cooling process, it can be compensated for by further molten polymer feedstock being fed into the mold cavity from manifold 24 and injection screw 10. It should be noted that it is also within the preview of this inven ⁇ tion to pack the molten material into the mold prior to initiating the reciprocation pattern. If this preliminary packing is performed, it can be accomplished by the continual rotation of screw 12, the inward movement of piston 32 and/or 34, and/or any combination thereof.
  • pistons 32 and 34 are preferably reciprocated in phase with each other to provide a packing force auxiliary to that of injection screw 10. This packing force is maintained until the polymer feedstock in the gate has solidified (see, Figure 4).
  • FIG. 5 is a detailed illustration of manifold 24 without pistons
  • Figure 6 is a cross-sectional side elevation of Figure 5 taken along line 6-6.
  • Figure 7 illustrates one method of controlling the reciprocation pattern and monitoring its effect on the material contained within a mold cavity in accordance with the present invention.
  • pistons 50 and 52 are reciprocated by motors 54 and 56, respectively.
  • Motors 54 and 56 can regulate the piston's frequency, amplitude and phase orientation.
  • the apparatus illustrated in Figure 7 also includes a means for controlling the temperature within the mold, manifold and/or injection screw. This is represented by temperature adjuster 57.
  • Temperature adjuster 57 can be a single device which controls the temperature in the mold, manifold and/or injection screw collectively or a series of devices which make these temperature adjustments independently.
  • Figure 7 represents the temperature adjusting device as a single unit even though it is understood that the temperature within the mold, manifold and/or injection screw will generally be different.
  • Temperature adjuster 57 can be used to increase, decrease or maintain a constant temperature within the mold, manifold and/or injection screw. This temperature control can be accomplished by any suitable means known to those skilled in the art.
  • temperature adjuster 57 can employ the implementation of the following: (a) hot and cold oil circulated through passages in the mold, manifold and/or injection screw, (b) resistance cartridges positioned within the mold, manifold and/or injection screw, (c) hot pipes inserted into the mold, manifold and/or injection screw, and/or (d) fluid which is embedded in the mold, manifold and/or injection screw and whose temperature can be con ⁇ trolled by dielectric means.
  • Central processing unit (CPU) 58 is connected to frequency controller 60, amplitude controller 62, phase controller 64 and temperature adjuster 57. Controllers 60, 62 and 64 are connected to motors 54 and 56. It should be noted that controllers 60, 62 and 64 can be part of CPU 58 and/or part of motors 54 and 56.
  • CPU 58 has programmed therein various reciprocation patterns wherein each pattern results in the final product having a specific mor- phological structure and/or physical properties. These reciprocation patterns also take into consideration specific temperature patterns.
  • CPU 58 will send the appropriate signals to con ⁇ trollers 60, 62 and 64 which, in turn, cause pistons 50 and 52 to reciprocate in accordance with a specific reciprocation pattern.
  • CPU 58 will also send the ap ⁇ intestinalte signal to temperature adjuster 57 which maintains the proper temperature pattern 41 in the mold, manifold and/or injection screw during the selected reciprocation pattern.
  • sensors 66, 67 and 68 are positioned accordingly. These sensors are connected to CPU 58.
  • CPU 58 can be programmed to modify and/or regulate the reciprocation and temperature patterns based, in part, on the information received from sensors 66, 67 and 68.
  • Sensors 66, 67 and 68 can be designed to monitor any desirable processing parameter such as compressive force, temperature, viscosity, etc. Moreover, similar sensors can be placed anywhere along the polymer flow path and/or at specific locations within the mold.
  • Figure 8 represents a schematic illustration of an injection molding apparatus which can be used when practicing the present invention.
  • injection screws 70 and 72 are used as the reciprocating means.
  • injection screws 70 and 72 mate with mold 74.
  • Mold 74 defines cavity 76 which communicates with injection screws 70 and 72 via conduits 78 and 80, respectively.
  • granular feedstock is fed from the feed hopper into the elongate cavity of each injection screw. These screw cavities are heated to melt the feedstock into a molted polymer.
  • the molten polymer When the molten polymer is determined to be of the right viscosi ⁇ ty, it is injected into mold cavity 76, by rotation and downstream translation of either one, or both of the injection screws.
  • injection screws 70 and 72 are reciprocated in accordance with one of the reciprocation patterns encompassed by the present invention. This reciprocation creates a shear force on the molten material within cavity 76 while, simultaneously, exerting a compressive force thereon. Shrinkage of the polymer feedstock during cooling can be compensated for by further molten polymer feedstock being fed into cavity 76 from injection screw 70 and/or 72.
  • injec ⁇ tion screws 70 and/or 72 are reciprocated such as to provide a packing force on the molten material within cavity 76. This packing force is maintained until the polymer feedstock has solidified.
  • the molten polymer Once the molten polymer has sufficiently solidified, it is removed from the mold cavity.
  • the resulting plastic material has unique properties which were created due to the specific reciprocation pattern.
  • Figures 9 and 10 represent a schematic illustration of a portion of a hot-runner-molding system which can be used when practicing the present invention. Specifically, Figure 9 represents a cross-sectional view of the hot- runner molding system illustrated in Figure 10 taken along line 9-9.
  • the drivable members are pistons 82 and 84. These pistons are designed to reciprocate in cylinders 86 and 88, respectively.
  • pistons 82 and 84 are driven by hydraulic plungers 90 and 92, respectively. Pistons 82 and 84 can, however, be driven by any suitable means known to those skilled in the art. In operation, molten polymer feedstock is fed through feed channel
  • pistons 82 and 84 are recipro- cated in one of the reciprocation patterns encompassed by the present invention. The specific reciprocation pattern is continued for a predetermined period of time until the desired results are achieved. Thereafter, pistons 82 and 84 are recipro ⁇ cated in a manner to exert a packing force on the molten material within cavity 98. This packing force is maintained until the molten material in cavity 98 0 PCI7US94/14605
  • Figures 11 and 12 represent a schematic illustration of a portion of a cold-runner molding system which can be used when practicing the present invention. Specifically, Figure 11 represents a cross-sectional view of the cold- runner molding system illustrated in Figure 12 taken along line 11-11.
  • the drivable members are pistons 118 and 120. These pistons are designed to reciprocate in cylinders 110 and 112, respectively.
  • pistons 118 and 120 are driven by hydraulic plungers 122 and 124, respectively.
  • pistons 118 and 120 can be driven by any suitable means known to those skilled in the art.
  • molten polymer feedstock is fed through feed channel
  • pistons 118 and 120 are reciprocated in one of the reciprocation patterns encompassed by the present invention.
  • the specific reciprocation pattern is continued for a predetermined period of time until the desired results are achieved.
  • pistons 118 and 120 are reciprocated in such a manner to exert a packing force on the molten material within cavity 104. This packing force is maintained until the molten polymer solidifies . Then, after the material has sufficiently solidified , it is removed from the mold cavity.
  • Figures 13 and 14 represent a schematic illustration of a portion of a cold-runner molding system which can be used when practicing this inven ⁇ tion, and which employs more than two reciprocation devices.
  • Figure 13 is a cross-sectional view of the cold-runner molding system illustrated in Figure 14 taken along line 13-13.
  • the drivable members are pistons 156, 158, 160 and 162. These pistons are designed to reciprocate in cylinders 140, 142, 144 and 146, respectively.
  • pistons 156, 158, 160 and 162 are driven by hydraulic plungers.
  • Figure 13 shows hydraulic plungers 155 and 157 for pistons 156 and 160, respectively.
  • pistons 156, 158, 160 and 162 can be driven by any suitable means known to those skilled in the art.
  • molten polymer is fed through feed channel 130 into cold-runner channel 132. Thereafter, the molten polymer flows into mold cavity
  • FIG. 15 is a graph which illustrates the action of two drivable members acting at different frequencies and amplitudes on a melt. Specifically, in this graph, P d is the dynamic pressure (peak to peak) on a molten polymer at a given point of the mold as measured by a suitable pressure sensor. Each point along the graph represents the apparent mass of the system in vibration which should be compared with the mass of the piston vibrating.
  • the graph also shows that the apparent mass is frequency depen- dent. This implies that the transmitted energy into the plastic is a function of frequency in a non-Newtonian manner.
  • the amplitude of the signal is also a rheological parameter that may vary during cooling, it is more appropriate to have several pistons each of which is designed to work in a specific frequency range. Thereafter, the signals from this plurality of pistons from the melt are combined together.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

Procédé de moulage d'un produit solidifié à partir d'un matériau moulable. Deux dispositifs à mouvement alternatif au moins (50, 52) en contact avec le matériau de moulage et comportant chacun un élément actionnable dans une chambre exercent un tenseur de contrainte avant et pendant la solidification. Ledit tenseur résulte du mouvement alternatif d'un des éléments actionnables par rapport à l'autre, selon un programme préétabli (58) qui peut être: a) même fréquence, amplitude différente et déphasés, b) même fréquence, amplitude différente et en phase, c) fréquence différente et même amplitude, et d) fréquence différente et amplitude différente. Le matériau moulable refroidit pendant son tassement pour former un produit solidifié.
PCT/US1994/014605 1994-12-19 1994-12-19 Transformation des caracteristiques physiques d'un materiau moulable Ceased WO1996019330A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU15528/95A AU1552895A (en) 1994-12-19 1994-12-19 Transforming physical characteristics of a moldable material
PCT/US1994/014605 WO1996019330A1 (fr) 1994-12-19 1994-12-19 Transformation des caracteristiques physiques d'un materiau moulable

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1994/014605 WO1996019330A1 (fr) 1994-12-19 1994-12-19 Transformation des caracteristiques physiques d'un materiau moulable

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WO1996019330A1 true WO1996019330A1 (fr) 1996-06-27

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2299780B (en) * 1995-04-11 1998-11-18 Brunel University Of West Lond Moulding process

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3616495A (en) * 1958-05-09 1971-11-02 Jerome H Lemelson Molding apparatus
US4288398A (en) * 1973-06-22 1981-09-08 Lemelson Jerome H Apparatus and method for controlling the internal structure of matter
US4469649A (en) * 1979-03-14 1984-09-04 Ibar Jean Pierre Method and apparatus for transforming the physical characteristics of a material by controlling the influence of rheological parameters
US4994220A (en) * 1988-03-31 1991-02-19 Kloeckner Ferromatik Des Gmbh Process for injection molding of injection molded parts of plasticized liquid crystal polymer material
US5059368A (en) * 1984-12-21 1991-10-22 National Research Development Corporation Method for molding a material containing alignable constituents

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3616495A (en) * 1958-05-09 1971-11-02 Jerome H Lemelson Molding apparatus
US3616495B1 (en) * 1958-05-09 1994-11-22 Jerome H Lemelson Molding apparatus
US4288398A (en) * 1973-06-22 1981-09-08 Lemelson Jerome H Apparatus and method for controlling the internal structure of matter
US4469649A (en) * 1979-03-14 1984-09-04 Ibar Jean Pierre Method and apparatus for transforming the physical characteristics of a material by controlling the influence of rheological parameters
US5059368A (en) * 1984-12-21 1991-10-22 National Research Development Corporation Method for molding a material containing alignable constituents
US4994220A (en) * 1988-03-31 1991-02-19 Kloeckner Ferromatik Des Gmbh Process for injection molding of injection molded parts of plasticized liquid crystal polymer material

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
COMPOSITES MANUFACTURING, Volume 1, Number 2, issued June 1990, ALLAN et al., "Development and Application of Multiple Live-Feed Moulding for the Management of Fibres in Moulded Parts", pages 79-84. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2299780B (en) * 1995-04-11 1998-11-18 Brunel University Of West Lond Moulding process

Also Published As

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