TECHNICAL FIELD
The present invention generally relates to, but is not limited to, molding systems, and more specifically the present invention relates to, but is not limited to molding systems having a barrel assembly.
BACKGROUND
Examples of known molding systems are (amongst others): (i) the HyPET (trademark) Molding System, (ii) the Quadloc (Trademark) Molding System, (iii) the Hylectric (trademark) Molding System, and (iv) the HyMET (trademark) Molding System, all manufactured by Husky Injection Molding Systems (Location: Canada; www.husky.ca).
U.S. Pat. No. 6,494,703 (Inventor: Kestle et al; Published: Dec. 17, 2002) discloses a barrel assembly for an injection molding machine, which includes a barrel coupler that prevents transmittance of an axial force from a nozzle side barrel portion to a rear side barrel portion. More specifically, this patent appears to disclose a barrel assembly that preferably has a first barrel coupler and a second barrel coupler. The first barrel coupler secures the barrel to a carriage. The second barrel coupler retains an end of the barrel in the carriage preventing rotation of the barrel during operation. The barrel section between the first barrel coupler and an end of the barrel is isolated from axial carriage force in operation.
U.S Pat. No. 6,520,762 (Inventor: Kestle et al; Published: Feb. 18, 2003) discloses an injection unit for an injection molding machine that has a carriage coupler and a barrel coupler which couples a barrel assembly to a carriage which is mounted on an injection unit. More specifically, it appears that this patent discloses a barrel assembly and carriage assembly preferably having first complimentary couplers and second complimentary couplers. The first couplers interlock to secure the barrel assembly between the ends of the barrel assembly to a carriage assembly. The second couplers retain an end of the barrel assembly in the carriage assembly preventing rotation of the barrel assembly during operation.
United States Patent Application Number 2002/0119213 (Inventor: Kestle et al; Published: Aug. 29, 2002) discloses a barrel and carriage assembly for isolating a barrel from axial forces. In one aspect, the entire barrel is isolated from axial carriage force. In another aspect, a portion of the barrel is isolated from axial carriage force. In another aspect, a portion of the barrel is isolated from reactive injection force.
United States Patent Application Number 2002/0150646 (Inventor: Kestle et al; Publication: Oct. 17, 2002) discloses a carriage assembly having a first carriage coupler and a second carriage coupler. The first carriage coupler secures a barrel intermediate the ends of the barrel to the carriage. The second carriage coupler retains an end of the barrel in the carriage preventing rotation of the barrel during operation. A barrel alignment member in the carriage provides axial and vertical alignment of the barrel assembly in the carriage assembly during installation of the barrel in the carriage.
U.S. Pat. No. 6,276,916 (Inventor: Schad et al; Published: Aug. 21, 2001) discloses a failsafe device, or pressure relief mechanism, for a shooting pot actuator in an injection molding machine. The shooting pot actuator has a multiple pusher rods mounted on one, or more, plates. Moving the plate holding the pusher rods depresses the shooting pot injection pistons and injects molten material into a number of mold cavities. To avoid damage to the machine from the pusher rods if an injection piston seizes, a failsafe device is used to mount the pusher rods to the plates. A shearing member is interposed, or sandwiched, between first and second apertures. Typically, the shearing member is a plate that, in normal operating conditions, blocks rearward movement of the pusher rod. However, when a predetermined shear force is applied to the shear plate, the shearing member shears and the pusher rod retracts within the channel, thereby alleviating the pressure. The failsafe device can be paired with a seizure detection system, using a laser beam that detects piston and valve gate seizure, and provides appropriate notification or control signals.
United States Patent Application Number 2005/0255189 (Inventor: Manda et al; Published: Nov. 17, 2005) discloses a method and an apparatus for a molding melt conduit and/or a runner system that includes a coupling structure having a first surface configured to couple with a first melt conduit or manifold, and a second surface configured to couple with a second melt conduit or manifold. A cooling structure is configured to provide a coolant to the coupling structure. Preferably, the cooling structure cools the coupling structure to a temperature that causes any melt leaking from near the coupling structure to at least partially solidify thereby further sealing the connection(s).
United States Patent Application Number 2006/0286197A1 (Inventor: Manda et al; Published: Dec. 21, 2006) discloses an expansion bushing of a molding runner system that includes a body having a portion configured to cooperate with a melt conduit. The body seals against the melt conduit responsive to a thermal expansion of the body relative to the melt conduit. Preferably, an annular expansion bushing has a cylindrical outer surface configured to seal, upon application of heat to the bushing, with an inner cylindrical surface of the first melt conduit and an inner cylindrical surface of the second melt conduit. Also preferably, the annular expansion bushing has an inner cylindrical surface corresponding substantially to melt passageways of the first and second melt conduits.
U.S. Pat. No. 5,096,406 (Inventor: Brooks et al; Published: Mar. 17, 1992) discloses an extruder assembly for composite materials, the extruder assembly having a barrel with feed and compression sections, a rotatable screw adapted to convey a composite material through the barrel, at least one fiber alignment means, and a die. The screw diameter in the feed section is approximately twice the screw diameter in the compression section, and the flight spacing in the feed section is approximately twice the flight spacing in the compression section. Column 1, lines 42 to 47, indicates that the “extruder assembly includes a screw-type extruder having a feed section and a compression section. The diameter of the barrel bore in the feed section is approximately double the diameter of the barrel bore in the compression section.”
U.S. Pat. No. 3,826,477 (Inventor: Kunogi et al.; Published: Jul. 30, 1974) discloses an injection molding machine having a vent opening on the heating barrel is disclosed which eliminates the clogging of the vent opening by the melt. This is attached by a step or steps in the size of the outer diameter of the screw and also steps in the size of the inner diameter of the barrel. The larger diameter portion of the barrel is located forwardly of the smaller diameter portion. The same is true of the screw. The vent opening is located in the portion of the device with a large barrel diameter but a small screw diameter. Column 2 lines 11 to 17, indicate that “a heating cylinder or barrel in FIG. 1 has a step 1′ before which a bigger inner-diameter D1 is bored and after which a smaller diameter D2. A screw has also one-stepped dual outer-diameters; the bigger d1 is slidably and rotatably mounted in the barrel part of inner diameter D1 to fit snugly therewith and similarly the smaller d2 with D2. Column 3, lines 7 to 15, indicate that “the melt being transferred from the zone II to the zone IR undergoes considerable reduction of pressure due to increase of the sectional area of the screw by changing the root diameter from d′1 to d′12, and far more reduction of pressure by passing the step 1′ of the barrel 1 because of rapid increase of the sectional area of the screw channel due to the change of the inner diameter from D2 to D1.”
There appears to be 18 years that separate U.S. Pat. No. 3,826,477 from U.S. Pat. No. 5,096,406.
SUMMARY
The inventor believes that persons of skill in the art do not understand the nature of the problem that is mitigated, at least in part, by the aspects of the present invention. The inventor notes that typical barrel assemblies associated with molding systems include a high-pressure section and a low-pressure section, which are bolted or connected together in an end to end fashion. In the low-pressure section, the molding material enters the barrel assembly and is made, while in the high-pressure section, the molding material is accumulated in an accumulation zone and is then injected, under a high pressure, into a mold.
The inventor notes that barrel assemblies of molding systems are costly to make, and it appears to the inventor that there are no publicly acknowledged approaches to mitigate the problem(s). The inventor notes that a user of molding systems may have to purchase several molding systems in order mold a wide range of moldable parts, and this arrangement may increase the cost per part molded. One molding system may have an 80 millimeter (mm) diameter barrel, while another molding system may have a 50 mm diameter barrel. The inventor notes that costs associated with manufacturing the 80 mm diameter barrel is much more than the 50 mm diameter barrel. The 80 mm diameter barrel has a larger capacity to deliver more molding material, especially when the molding material has to be injected quickly into a mold cavity (or cavities) so as to substantially avoid inadvertently freezing the molding material before the mold cavity is properly filled and packed out. Molded parts made with an 80 mm diameter barrel may be larger than molded parts made with a 50 mm diameter barrel. Also, a lower cost molding system would be advantageous for reducing cost per part molded. The inventor believes that he has identified the above-mentioned problem, and the inventor believes that the aspects of the present invention mitigate (at least in part) the above-mentioned problem.
According to a first aspect of the present invention, there is provided a molding system, having a barrel assembly, including: a low-pressure section configured to be operatively couplable with a high-pressure section, the high-pressure section being selected from a set of high-pressure sections.
According to a second aspect of the present invention, there is provided a molding system, having a barrel assembly, including: a high-pressure section configured to be operatively couplable with a low-pressure section, the high-pressure section being selected from a set of high-pressure sections.
According to a third aspect of the present invention, there is provided a molding-system method, including operatively coupling a low-pressure section with a high-pressure section, the low-pressure section and the high-pressure section being associated with a barrel assembly, the high-pressure section being selected from a set of high-pressure sections.
The technical effect, of amongst others, associated with the foregoing aspects of the present invention is cost reduction in the cost of molding systems, and therefore cost reduction in molded part. The low-pressure section does not change, but the high-pressure sections may be swapped out for other high-pressure sections. In this fashion, the user of the molding system may reduce the cost of acquiring or purchasing a molding system that may have a larger range of types or sizes of parts that may be molded, without having to own may molding systems to handle such a wide range of parts to be molded.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the non-limiting embodiments of the present invention (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the non-limiting embodiments of the present invention along with the following drawings, in which:
FIG. 1 depicts a schematic representation of a molding system 10 according to the first non-limiting embodiment, the second non-limiting embodiment, the third non-limiting embodiment, and the fourth non-limiting embodiment;
FIG. 2 depicts a perspective view of the molding system 10 of FIG. 1 according to the fifth non-limiting embodiment and the sixth non-limiting embodiment;
FIG. 3 depicts a cross-sectional view of the molding system 10 of FIG. 1 according to the seventh non-limiting embodiment;
FIG. 4 depicts an exploded perspective view of the molding system 10 of FIG. 1 according to an eighth non-limiting embodiment;
FIG. 5 depicts a cross-sectional view of the molding system 10 of FIG. 1 according to the eighth non-limiting embodiment;
FIG. 6 depicts a schematic representation of the molding system 10 according to the seventh non-limiting embodiment (which is the preferred embodiment or best mode);
FIG. 7 depicts a cross-sectional view of the molding system 10 of FIG. 1 according to the eighth non-limiting embodiment;
FIG. 8 depicts a cross-sectional view of the molding system 10 of FIG. 1 according to the eighth non-limiting embodiment;
FIGS. 9A, 9B, 9C depict schematic representations of the molding system 10 of FIG. 1 according to the ninth non-limiting embodiment;
FIG. 10 depicts a schematic representation of the molding system 10 of FIG. 1 according to the tenth non-limiting embodiment;
FIG. 11 depicts a schematic representation of: (i) a metal injection molding system 10 according to an eleventh non-limiting embodiment, and (ii) a method 500 of the metal injection molding system 10 according to a twelfth non-limiting embodiment; and
FIGS. 12A and 12B depict cross-sectional views of the molding system 10 of FIG. 11 according to a thirteenth non-limiting embodiment.
The drawings are not necessarily to scale and are sometimes illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 depicts the schematic representation of a metal injection molding system 10 (hereafter referred to as the “system 10”) according to the first non-limiting embodiment, the second non-limiting embodiment, the third non-limiting embodiment, and the fourth non-limiting embodiment. The system 10 includes components that are known to persons skilled in the art and these known components will not be described here; these known components are described, at least in part, in the following text books (by way of example): (i) Injection Molding Handbook by Osswald/Turng/Gramann (ISBN: 3-446-21669-2; publisher: Hanser), and (ii) Injection Molding Handbook by Rosato and Rosato (ISBN: 0-412-99381-3; publisher: Chapman & Hill). The system 10 is, preferably, configured to process a metal molding material, such as an alloy of magnesium (preferably in a thixotropic state, otherwise known as a slurry state, or in a liquidus state), an alloy of aluminum, an alloy of zinc, etc. A molded article 999 is manufactured by usage of the system 10.
According to the first non-limiting embodiment, the system 10 includes: an extruder 12, a clamp assembly 25, and a conduit connection 100 (of which an example is depicted in FIG. 2). The extruder 12 may be (by way of example): (i) a reciprocating-screw (RS) extruder, or (ii) a two-stage extruder that has a shooting pot configuration. The extruder 12 has: (i) a hopper 14, (ii) a feed throat 16, (iii) a conduit assembly 218, (iv) a screw 18, (v) a screw actuator 20, and (vi) a machine nozzle 22. The hopper 14 is configured to receive a flowable molding material. The feed throat 16 is coupled to the hopper 14. The feed throat 16 receives, in use, the flowable molding material from the hopper 14. The conduit assembly 218 includes: (a) a first conduit 106, and (b) a second conduit 116. The first conduit 106 interacts with the feed throat 16, and receives, in use, the flowable molding material from the feed throat 16. The second conduit 116 is coupled to the first conduit 106. The screw 18 is received in the first conduit 106. The screw actuator 20 is coupled to the screw 18, and the screw actuator 20, in use when so made to cooperate with the screw 18, performs the following functions: (i) convert the flowable molding material received in the first conduit 106 into an injectable molding material, and (ii) push the injectable molding material from the first conduit 106 to the second conduit 116. The machine nozzle 22 is coupled to the second conduit 116. The clamp assembly 25 includes: (i) a stationary platen 26, (ii) a movable platen 28, (iii) a mold stroke actuator 30, (iv) tie bars 32, (iv) a lock 34, and (iv) a clamp actuator 36. The stationary platen 26 is configured to support a stationary mold portion 29 of a mold assembly 24. The stationary mold portion 29 is configured to receive the injectable molding material from a hot runner 38. The hot runner 38 is configured to be coupled to the machine nozzle 22 and is also configured to receive the injectable molding material from the machine nozzle 22. The movable platen 28 is configured to: (a) support a movable mold portion 21 of the mold assembly 24, and (b) move relative to the stationary platen 26 so as to close the movable mold portion 21 against the stationary mold portion 29. The movable mold portion 21 is movable relative to the stationary mold portion 29. The stationary mold portion 29 and the movable mold portion 21 define, in combination, a mold cavity 27 once the movable mold portion 21 abuts against the stationary mold portion 29. The mold cavity 27 is fillable with the injectable molding material to be received from the machine nozzle 22 (via the hot runner 38), under pressure from the second conduit 116, once the screw 18 has been actuated to inject the injectable molding material. The mold stroke actuator 30 is coupled to the movable platen 28, and is configured to stroke the movable platen 28. The tie bars 32 are attached to respective corners of the stationary platen 26. The tie bars 32 are interactable with respective corners of the movable platen 28. The lock 34 is configured to lockably engage the movable platen 28 with the tie bars 32. The clamp actuator 36 is configured to impart a clamping force, in effect, to the stationary platen 26 and the movable platen 28 once: (i) the movable mold portion 21 is closed against the stationary mold portion 29, and (ii) the movable platen 28 is locked to the tie bars 32.
With reference to FIG. 2, the conduit connection 100 includes: (i) a first flange 102, and (ii) a second flange 112. The first flange 102 is coupled to a first port 104 (such as an exit port) of the first conduit 106 of a conduit assembly 218. The second flange 112 is coupled to a second port 114 (such as an input port) of the second conduit 116 of the conduit assembly 218. The second flange 112 is sealably engaged with the first flange 102. The second port 114 is aligned with the port 104 so that the injectable molding material may flow from the first conduit 106 to the second conduit 116. It will be appreciated that the mold assembly 24 and the hot runner 38 are typically sold separately from the extruder 12 and the clamp assembly 25. The mold assembly 24 wears over time and as such it is replaced as may be required. The hot runner 38 is usually matched to meet the requirements of the mold assembly 24, and as such is typically not usable with another mold assembly (not depicted) having a different configuration. According to a preferred implementation, the first conduit 106 includes a low-pressure section 222 of a barrel assembly 220, the second conduit 116 includes a high-pressure section 224 of the barrel assembly 220, and the conduit assembly 218 includes the barrel assembly 220. The low-pressure section 222 is the part of the barrel assembly 220 in which pellets of molding material (received from the hopper 14) are processed into the injectable moldable molding material, and the high-pressure section 224 is the part of the barrel assembly 220 in which the injectable molding material is accumulated and then injected or pushed, under pressure, to the mold cavity 27 (or cavities) of the mold assembly 24 via the machine nozzle 22 and hot runner 38.
According to the second non-limiting embodiment (not depicted), the mold assembly 24 includes a single mold cavity (not depicted); in this case, the system 10 does not use (or include) the hot runner 38, and the system 10 is arranged so that: (i) the machine nozzle 22 is coupled to the second conduit 116, (ii) the stationary mold portion 29 is coupled to the machine nozzle 22, and receives, in use, the injectable molding material from the machine nozzle 22, (iii) the mold cavity 27 is fillable with the injectable molding material to be received from the machine nozzle 22, under pressure from the second conduit 116, once the screw 18 has been actuated to inject (or push) the injectable molding material.
According to the third non-limiting embodiment, the system 10 includes only the extruder 12, and does not include the clamp assembly 25.
According to the fourth non-limiting embodiment, the system 10 includes the hot runner 38, and does not include the extruder 12 and the clamp assembly 25. The hot runner 38 includes: (i) the conduit assembly 218, and the conduit connection 100. The conduit assembly 218 includes: (i) a first conduit 106, and (ii) a second conduit 116. The first conduit 106 is configured to: (a) be interactable with a machine nozzle 22, and (b) receive, in use, an injectable molding material from the machine nozzle 22. The second conduit 116 is configured to: (a) be coupled to the first conduit 106, (b) be coupled to a stationary mold portion 29 of a mold assembly 24, (c) convey, in use, the injectable molding material from the first conduit 106 to a mold cavity 27 defined by a mold assembly 24. The conduit connection 100 includes: (i) a first flange 102, and (ii) a second flange 112. The first flange 102 is coupled to the port 104 of the first conduit 106 of the conduit assembly 218. The second flange 112 is coupled to the second port 114 of the second conduit 116 of the conduit assembly 218. The second flange 112 is sealably engaged with the first flange 102. The second port 114 is aligned with the port 104 so that an injectable molding material may flow from the first conduit 106 to the second conduit 116.
FIG. 2 depicts the perspective view of the system 10 of FIG. 1 according to the fifth non-limiting embodiment and the sixth non-limiting embodiment. According to the fifth non-limiting embodiment, the system 10 includes the conduit assembly 218, but does not include the extruder 12, the clamp assembly 25 and the hot runner 38 (that is, the conduit assembly 218 is sold separately).
The conduit assembly 218, preferably, includes the barrel assembly 220; specifically, the conduit assembly 218 includes: (i) the first conduit 106, (ii) the second conduit 116, and (iii) the conduit connection 100. Preferably, the first conduit 106 includes the low-pressure section 222 of the barrel assembly 220 of the extruder 12. The low-pressure section 222 is coupled to the feed throat 16 of the extruder 12. The low-pressure section 222 is configured to receive, in use, a flowable molding material from the feed throat 16. The second conduit 116 includes a high-pressure section 224 of the barrel assembly 220. The high-pressure section 224 is coupled to the low-pressure section 222. Alternatively, the conduit assembly 218 is used in the hot runner 38.
According to the sixth non-limiting embodiment, the system 10 includes the conduit connection 100 but does not include the conduit assembly 218, the extruder 12, the hot runner 38, and the clamp assembly 25 (that is, the conduit connection 100 is sold separately). Optionally, the first flange 102 is coupled to the second flange 112 via the bolts 221. The first conduit 106 is configured to be a low-pressure section 222, and the second conduit 116 is configured to be a high-pressure section 224, the high-pressure section 224 defines a heater groove 223 (hereafter referred to as the “groove 223”) that receives a heater wire (not depicted in FIG. 2). An alignment dowel 119 (hereafter referred to as the “dowel 119”) is used to align the first flange 102 with the second flange 112. Preferably, two dowels 119 are used on opposite sides of the flanges 102, 112 (a single dowel 119 is depicted in FIG. 2).
FIG. 3 depicts the cross-sectional view of the system 10 of FIG. 1 according to the seventh non-limiting embodiment. The cross-sectional view is taken along a section line A-A that is shown in FIG. 2; the section line A-A: (i) extends along a longitudinal axis 219 of the barrel assembly 220, and (ii) passes through the dowels 119. The first flange 102 defines passageways that are sized to receive respective dowels 119 on opposite sides of the first flange 102. The high-pressure section 224 includes a second shell 270 that defines channels that are located on opposite sides of the second shell 270, and these channels are sized to receive respective dowels 119. The dowels 119 extend into the second shell 270 and extend into the first flange 102 so that the first flange 102 cannot be rotated relative to the high-pressure section 224. The second flange 112 defines a centrally-aligned passageway (that extends through the second flange 112) that is sized smaller than a centrally-aligned passageway defined by the first flange 102. The first flange 102 threadably engages, via threads 252, the first conduit 106. The second flange 112 threadably engages, via threads 250, the second conduit 116. The screw 18 is depicted positioned in an end of an injection cycle of the system 10 in which a shot was injected into the mold cavity 27 of the mold assembly 24. The screw 18 includes a screw flight 19 that extends from the outer periphery of the screw 18 toward the inner diameter of the low-pressure section 222. The high-pressure section 224 and the low-pressure section 222 are aligned along the longitudinal axis 219. The high-pressure section 224 defines: (i) an accumulation zone 217, and (ii) an exit port 215 that leads from the accumulation zone 217 to the machine nozzle 22. The high-pressure section 224 is configured to securely receive a support cap 213. The support cap 213 is threadably secured to the high-pressure section 224. The machine nozzle 22 (not depicted in FIG. 3) is to be mounted to the support cap 213.
At a distal end of the high-pressure section 224, a shoulder 233 extends from the outer diameter of the high-pressure section 224 so that the second flange 112 may abut against the shoulder 233. At a distal end of the low-pressure section 222, the low-pressure section 222 defines a spigot 227 that extends from the distal end of the low-pressure section 222. The first flange 102 defines a passageway that extends through the first flange 102, and the passageway has an inner diameter that is sized to receive the passageway of the low-pressure section 222. At room temperature, the first flange 102 and the second flange 112 define a gap 211 therebetween, once the flanges 102, 112 are made to abuttably contact each other at least in part. More specifically, the flanges 102, 112 contact each other at peripheral edges of the flanges 102, 112 at room temperature. If the flanges 102, 112 are bolted together, they are bolted at 50% of rated torque of the bolts 221 so that the flanges 102, 112 may substantially touch each other at an operational temperature of the barrel assembly 220, which is approximately 620 degrees Centigrade if the system 10 is being used to mold a magnesium alloy. The gap 211 is, preferably, 1 millimeter (hereafter referred to as “mm”) at room temperature, but the gap 211 becomes substantially zero mm at the operating temperature of the barrel assembly 220 so that flanges 102, 112 substantially touch each other (thereby substantially eliminating the gap 211). At room temp, the bolts 221 help to keep the flanges 102, 112 together; at operating temperature (such as, at approximately 620 degrees Centigrade), thermal loading keeps the flanges 102, 112 together. The thermal loading arrangement is depicted and described in detail in association with FIG. 6. A valve 201 (which is also known as a check valve) is connected to the distal end of the screw 18. The function and the structure of the valve 201 are well known, and as such the valve 201 will not be described here in detail. A function of the valve 201 is to prevent leaking of the injectable molding material back over the screw flight 19 of the screw 18 during injection of a shot of the injectable molding material into the mold cavity 27. The valve 201 may be a cylindrical plate or a spherical member or a conical member. The valve 201 is disclosed, for example, in United States Patent Number 2,885,734 (Inventor: Wucher; Published: 12 May 1959).
Preferably, the low-pressure section 222 includes: (i) a first shell 260, and (ii) a first liner 262 that is received in the first shell 260. If the system 10 is used to mold a metallic alloy of magnesium, the first shell 260 is made substantially of Inconel alloy 718 (Supplier: Special Metals Corporation, Huntington, W.Va., USA; http://www.specialmetals.com), and the first liner 262 is made substantially of Stellite (trademark), and the first liner 262 is shrink fitted with the first shell 260. The low-pressure section 222 includes: (i) an outer surface that defines a heater groove 264, (ii) a heater wire 266 that is received in the heater groove 264, and (iii) a heater band 268 that that surrounds the heater wire 266. The heater band 268 is configured to maintain the heater wire 266 in substantial contact with the heater groove 264.
The high-pressure section 224 includes: (i) the second shell 270, and (ii) a second liner 272 that is received in the second shell 270. If the system 10 is used to mold a metallic alloy of magnesium, the second shell 270 is made substantially of Inconel alloy 718, and the second liner 272 is made substantially of Stellite (trademark) (Vendor: Stellite Coatings, 1201 Eisenhower Drive N., Goshen, Ind. 46526 USA; www.stellite.com) that is received in the second shell 270, and the second liner 272 is shrink fitted to the second shell 270. The high-pressure section 224 includes: (i) an outer surface defining a heater groove 274, (ii) a heater wire 276 that is received in the heater groove 274, and (iii) a heater band 278 that surrounds the heater wire 276. The heater band 278 is configured to maintain the heater wire 276 in substantial contact with the heater groove 274.
FIG. 4 depicts the exploded perspective view of the system 10 of FIG. 1 according to the eighth non-limiting embodiment. Specifically, FIG. 4 depicts additional details associated with the conduit assembly 218 and the barrel assembly 220. Preferably, the barrel assembly 220 includes: (i) a load ring 280, (ii) an injection housing 282, (iii) a yoke 284, (iv) a yoke locating pin 288, and (v) a mechanical fuse assembly 290. The load ring 280 abuts the second flange 112 of the high-pressure section 224. The injection housing 282 supports, at least in part, the low-pressure section 222. The yoke 284 supports, at least in part, the high-pressure section 224, The yoke 284 is attached to the injection housing 282 via bolts 286. The yoke locating pin 288 interacts with the yoke 284 and the injection housing 282 so as to align the yoke 284 with the injection housing 282. The mechanical fuse assembly 290 is coupled to the injection housing 282. The mechanical fuse assembly 290 is also coupled to the first flange 102 of the low-pressure section 222. The mechanical fuse assembly 290 includes: (i) a base unit 292, and a fuse element 296. The base unit 292 is coupled to the injection housing 282 via bolts 294. The fuse element 296 is interactable with the base unit 292. According to variants, the following may be considered for other embodiments (which are not depicted): (i) the mechanical fuse assembly 290 is coupled to the first flange 102, and/or (ii) the mechanical fuse assembly 290 is coupled to the second flange 112. The mechanical fuse assembly 290 includes: (i) a base unit 292, and (ii) a fuse element 296 that is interactable with the base unit 292.
FIG. 5 depicts the cross-sectional view of the system 10 of FIG. 1 according to the eighth non-limiting embodiment. Specifically, FIG. 5 depicts the conduit assembly 218 and the barrel assembly 220. No loading forces are made to interact with the parts of the barrel assembly 220. An injection path 23 is the path that the injectable molding material will travel along. The mechanical fuse assembly 290 is aligned parallel to and offset from the longitudinal axis 219 of the low-pressure section 222. The injection housing 282 defines cooling circuits 291, and the yoke 284 defines cooling circuits 291. The purpose of the cooling circuits 291 will be explained in the description associated with FIG. 6. The cooling circuits 291 are positioned proximate to the load ring 280 and proximate to the injection housing 282 (next to the mechanical fuse assembly 290).
FIG. 6 depicts the schematic representation of the system 10 according to the seventh non-limiting embodiment. According the seventh non-limiting embodiment, the system 10 includes: (i) a conduit clamp 400, and (ii) the conduit connection 100. According to a variant, the conduit clamp 400 and the conduit connection 100 are sold separately. Preferably, the conduit clamp 400 includes the combination of: (i) the cooling circuits 291, (ii) the load ring 280, (iii) the yoke 284, (iv) the injection housing 282, (v) the mechanical fuse assembly 290, and (iv) the dowel 119. The yoke 284 is made of stainless steel. The injection housing 282 is made of cast iron. The first flange 102, the second flange 112, the dowel 119, and the mechanical fuse assembly 290 (components thereof) are made of Inconel alloy 718 because these components are located proximate to the barrel assembly 220. The cooling circuits 291 are used for thermal management of the injection housing 282, the yokes 284 and the load ring 280. The conduit clamp 400 includes, preferably, the cooling circuits 291 that are configured to maintain the conduit clamp 400 at the relatively low temperature. The cooling circuits 291 carries a coolant (such as water) that is used to keep the conduit clamp 400 cooled and therefore in a rigid state. The conduit connection 100 is operated at an operating temperature that is relatively higher than that of the conduit clamp 400. The conduit connection 100 is retained in the conduit clamp 400. The conduit connection 100 includes: (i) the first flange 102 and (ii) the second flange 112. The conduit clamp 400 is configured to maintain the first flange 102 and the second flange 112 substantially sealed against each other so that the injectable molding material may flow from the first conduit 106 to the second conduit 116 without substantially leaking from the conduit connection 100. FIG. 6 depicts the first conduit 106 embodied as the high-pressure section 224, and depicts the second conduit 116 embodied as the low-pressure section 222. The conduit connection 100 becomes heated as a result of heat contained in the injectable molding material that is contained in the conduit assembly 218. Responsive to the conduit connection 100 being heated to operating temperature, the conduit connection 100 expands and imposes a thermal expansion force 300 to the conduit clamp 400. The conduit clamp 400 responds by acting to constrain thermal expansion of the conduit connection 100 because the conduit clamp 400 is maintained at a relatively lower temperature and an in this manner, the conduit clamp 400 imposes a clamping force 302 that counteracts the thermal expansion force 300. A sealing force 308 is imposed at the inner peripheral edge of the first conduit 106 and the second conduit 116. The sealing force 308 is merely the effect created as a result of thermal expansion of the conduit connection 100.
The first flange 102 is, preferably, coupled to the second flange 112 via thermal loading. According to the embodiment depicted in FIG. 2, the flanges 102, 112 are bolted together at 50% of rated torque of the bolts 221 so that the gap 211 (depicted in FIG. 3), which exists at room temperature, disappears (preferably) and this manner the first flange 102 and the second flange 112 touch each other at the operating temperature of the barrel assembly 220. It is preferred to use the combination of: (i) the bolts 221, and (ii) the thermal load (that is, the effect achieved by the conduit clamp 400) to maintain the flanges 102, 112 sealed against each other. However, according to a variant, (i) the flanges 102, 112 are assembled without using the bolts 221, and (ii) the flanges 102, 112 thermally expand against the conduit clamp 400 as the conduit clamp 400 is kept at a relatively lower temperature (so that the conduit clamp 400 may constrain the flanges 102, 112 against each other) in response to the barrel assembly 220 becoming heated to the operating temperature of the barrel assembly 220. The barrel assembly 220, when used in a metal injection molding system (such as for injecting a molten alloy of magnesium), will reach temperatures of over 600 degrees Centigrade. In this arrangement, thermal loading maintains the flanges 102, 112 in a sealing arrangement relative to each other. The thermal expansion force 300 is associated with the flanges 102, 112. The thermal expansion force 300 is equal to an opposite in direction to the clamping force 302 so that in this manner, the flanges 102, 112 remain static so as to maintain the seal between the flanges 102, 112.
FIG. 7 depicts the cross-sectional view of the system 10 of FIG. 1 according to the eighth non-limiting embodiment. Specifically depicted is a cross-sectional view of the barrel assembly 220. The position of the screw 18 is in a beginning of an injection cycle of the system 10 before a shot is injected from the accumulation zone 217 into the mold cavity 27 of the mold assembly 24. The screw actuator 20 is actuated so as to drive the screw 18 forward toward the machine nozzle 22, toward the clamp assembly 25 (located on the left side of FIG. 7) along a load path of an injection force 304 that begins at the screw actuator 20 (located on the right side of FIG. 7). The injection force 304 is transmitted from the screw actuator 20 to the screw 18. In response to receiving the injection force 304, the screw 18 is driven toward the machine nozzle 22. In doing so, the screw 18 pushes against and moves the injectable molding material that is contained in the accumulation zone 217 into the machine nozzle 22 and into the mold cavity 27 of the mold assembly 24. However, part of the injectable molding material located in the accumulation zone 217 becomes pushed against the high-pressure section 224 so as to urge the high-pressure section 224, the second flange 112, the load ring 280 and the yoke 284 toward the clamp assembly 25. However, the high-pressure section 224 is maintained in a static condition because the bolts 286 react by generating a reaction force 287 that is opposite but equal in magnitude to the force acting on the high-pressure section 224.
FIG. 8 depicts the cross-sectional view of the system 10 of FIG. 1 according to the eighth non-limiting embodiment. Specifically, the screw 18 is depicted in a pull back cycle (sometimes referred to as “suck back”) of the system 10, in which the screw 18 is retracted or pulled back along a direction that extends away from the machine nozzle 22. The screw actuator 20 imposes or imparts a pull back force 306 to the screw 18. Since the valve 201 is attached to the distal end of the screw 18, the valve 201 is also pulled backward so that the valve 201 is made to drag along the inner diameter of the high-pressure section 224; the pull back force 306 is imparted (transmittable) to the high-pressure section 224, which is then transferred to the second flange 112, then to the first flange 102, then to the mechanical fuse assembly 290, and then to the injection housing 282. Since the injection housing 282 is attached to a stationary frame, the injection housing 282 will generate a reaction force 289 that is equal in magnitude to the pull back force 306 but acts in the opposite direction of the pull back force 306, so that in effect, the injection housing 282 remains stationary once the pull back force 306 is imposed to the screw 18. Under the presence of the pull back force 306, the mechanical fuse assembly 290 does not blow (that is, the mechanical fuse assembly 290 maintains its integrity and does not disintegrate). The mechanical fuse assembly 290 withstands the pull back force 306 as the screw 18 is driven backward under application of the pull back force 306.
FIGS. 9A, 9B, 9C depict the schematic representations of the system 10 of FIG. 1 according to the ninth non-limiting embodiment. FIGS. 9A and 9B depict the mechanical fuse assembly 290. The base unit 292 defines a channel 316 that extends from a front side to a back side of the base unit 292. The fuse element 296 includes: (i) a core body 310 that is sized to be slidably received, at least in part, in the channel 316, and (ii) a frangible part 312 that extends radially from a periphery of the core body 310. If the system 10 is used to mold a metallic molding material, the fuse element 296 is made of Stellite. The frangible part 312 is sized to be larger than the channel 316. In the presence of an applied force 318 that is applied to the core body 310, the frangible part 312 is designed to break away from (that is, shear from) the core body 310 along a break line 314 (the break line 314 defines the outer diameter of the core body 310 that is less than the diameter of the channel 316. As depicted in FIG. 9B, once the frangible part 312 is broken away from the core body 310, the core body 310 may slide along the channel 316 (under the influence of the applied force 318), and the frangible part 312 falls away from the core body 310. The core body 310 does not break from the frangible part 312 when the core body 310 (that is, the mechanical fuse assembly 290) receives the pull back force 306. The mechanical fuse assembly 290 may also be referred to as a shear pin. FIG. 9C depicts the screw actuator 20. The screw actuator 20 includes: (i) a cylinder 320 that has a bore side 324 and also has a rod side 322, (ii) a piston 326 that is slidable within the cylinder 320 between the bore side 324 and the rod side 322, and (iii) a rod 328 that is attached to the piston 326 and extends through the rod side 322 so as to connect to the screw 18.
FIG. 10 depicts the schematic representation of the system 10 of FIG. 1 according to the tenth non-limiting embodiment. A fuse overload condition occurs when the force applied to the frangible part 312 becomes large enough to cause the frangible part 312 to shear from (detach from) the core body 310. The fuse overload condition exists when two events occur at same time: (i) the piston 326 has bottomed out against a bottom 325 of the rod side 322 (thus collapsing the rod side 322), and (ii) the screw 18 and the low-pressure section 222 cool off enough so that the region that is located between the screw 18 and the low-pressure section 222 becomes cooled off so that the injectable molding material that is located between the screw 18 and the low-pressure section 222 becomes solidified into a solidified molding material 327 (in effect, the screw 18 becomes welded to the low-pressure section 222); in turn, the screw 18 continues to cool off and shrink. Opposite ends of the screw 18 become pulled toward the solidified molding material 327. As a result, a screw connection 330 (that connects the screw 18 to the rod 328) experiences stresses that may inadvertently damage the screw connection 330 (that is damage between: (i) the rod 328 and the screw connection 330, and/or (ii) the screw connection 330 and the screw 18). The screw 18 contracts and thus imparts a contraction force 329 to the low-pressure section 222, which is then transferred to the first flange 102 and then to the core body 310. Once the screw 18 shrinks beyond a predetermined amount, the contraction force 329 becomes large enough to cause the frangible part 312 to break away from the core body 310, and the contraction force 329 causes the core body 310 to travel into the channel 316 along a path 331. Once the core body 310 travels along the path 331, the screw 18 may continue shrinking and thus pull the low-pressure section 222 toward the screw connection 330 without fear of causing inadvertent damage to the screw connection 330. The mechanical fuse assembly 290 provides thermal protection to the screw connection 330 when (i) the screw 18 becomes welded to the low-pressure section 222 (as a result of cooling off), and (ii) the piston 326 becomes bottomed. The condition where the mechanical fuse assemblies 290 are expected to “blow” or yield (that is, become broken along the break line 314) is when the system 10 experiences an inadvertent shutdown condition, in which electrical power is shut off. In this case, the electrical heaters that are coupled to the barrel assembly 220 will no longer provide heat to the injectable molding material located in the low-pressure section 222 and the high pressure section 224; and the injectable molding material will cool off so as to weld the screw 18 to the low-pressure section 222 and the high pressure section 224. Power to the screw actuator 20 is shut down and the screw actuator 20 is bottomed out. As the screw 18 continues to cool off, the screw 18 will shrink. The mechanical fuse assembly 290 will permit the low-pressure section 222 and the high pressure section 224 to move along with the screw 18 as the screw 18 continues to shrink due to loss of power to the heaters. In this manner, the screw connection 330 is saved from being damaged as a result of shrinkage of the screw 18 provided that the mechanical fuse assemblies 290 operate. Without the mechanical fuse assemblies 290, the screw connection 330 may suffer inadvertent damage as a result of the heaters of the low-pressure section 222 and the high pressure section 224 loosing electrical power.
FIG. 11 depicts the schematic representation of: (i) the metal injection molding system 10 (hereafter referred to as the “system 10”) according to the eleventh non-limiting embodiment, and (ii) the method 500 according to the twelfth non-limiting embodiment. According to the eleventh non-limiting embodiment, the system 10 has the barrel assembly 220. The barrel assembly 220 includes: (i) a low-pressure section 222, and (ii) a set 230 of high-pressure sections 224, 226, 228, 229. Each high-pressure section 224, 226, 228, 229 that is selectable from the set 230 is configured to be operatively couplable with the low-pressure section 222. According to the eleventh non-limiting embodiment, the operator of the system 10 purchases the barrel assembly 220 that has the low-pressure section 222 and the set 230, and then the operator selects a desired one of the high-pressure sections from the set 230, depending on the criteria associated with the part to be molded. The high-pressure section 224 has a smaller outer diameter (OD) and a smaller inner diameter (ID) in comparison with the OD and the ID associated with the high-pressure section 226. For example, if the part to be metallic molded is a dimensionally small part (such as a cell-phone housing, etc), perhaps using the high-pressure section 224 may be suitable for use with the low-pressure section 222 because the high-pressure section 224 can better address the processing requirements associated with molding a smaller moldable part. Alternatively, if the part to be molded is a dimensionally large part (such as an automotive component or a housing for an electric motor, etc), perhaps using the high-pressure section 226 may be suitable or appropriate because the high-pressure section 226 may better address the needs associated with processing and molding dimensionally larger molded parts. This arrangement permits greater flexibility for the operator of the system 10 to make a wider range of molded parts, without having to resort to purchasing and using differently sized molding systems to manufacture the wider range of molded parts.
According to a first variant of the eleventh non-limiting embodiment, the low-pressure section 222 is configured to be operatively couplable with a selected high-pressure sections 224, 226, 228, 229 (selected from the set 230). Any one of the high-pressure sections 224, 226, 228, 229 is selected from the set 230 of high-pressure sections 224, 226, 228, 229. The set 230 may have two or more high-pressure sections that are selectable to coupling with the low pressure section 222. The non-limiting embodiment depicted in FIG. 11 shows four high-pressure sections that are members of the set 230. According to the first variant of the eleventh non-limiting embodiment, the operator of the system 10 purchases the barrel assembly 220 that has one low-pressure section, and then in the future, the operator may purchase one or more high-pressure sections as may be required. In this case, the operator may purchase the system 10 in advance without having to commit to purchasing the high-pressure sections along with the system 10.
According to a second variant of the eleventh non-limiting embodiment, the barrel assembly 220 includes a selected high-pressure section that is configured to be operatively couplable with the low-pressure section 222. The selected high-pressure section is selected from the set 230 of high-pressure sections (any one of the high-pressure sections 224, 226, 228 and/or 229). In this case, the operator of the system 10 may purchase one high-pressure section today, and then purchase another high-pressure section selected from the set 230 in the future when so required.
According to a third variant of the eleventh non-limiting embodiment, the barrel assembly 220, including: (i) a low-pressure section 222 and (ii) a selected high-pressure section 224, 226, 228, 229. In this case, the operator of the system 10 may purchase one high-pressure section and one low-pressure section at the time of purchasing the system 10, and some time in the future, the operator may purchase additional high-pressure sections as may be required.
The method 500 includes operatively coupling the low-pressure section 222 with a selected high-pressure section (either high-pressure section 224, 226, 228 and/or 229) that is selected from the set 230. The molded article 999 is manufactured by usage of: (i) the system 10, or (ii) the method 500.
According to the following non-limiting variants: (i) the low-pressure section 222 is configured to be operatively couplable with each high-pressure section 224, 226, 228, 229 associated with the set 230 of high-pressure sections, (ii) the low-pressure section 222 has: (a) an outer diameter that is the same as the outer diameter of a selected high-pressure section 224, and (b) an inner diameter that is the same as the inner diameter of the selected high-pressure section 224, (iii) the low-pressure section 222 has: (a) an outer diameter that is smaller than the outer diameter of a selected high-pressure section 226, and (b) an inner diameter that is smaller than the inner diameter of the selected high-pressure section 226, (iv) the low-pressure section 222 has: (a) an inner diameter that is smaller than the inner diameter of a selected high-pressure section 228, and (b) an outer diameter that is the same as the outer diameter of the selected high-pressure section 228, (v) the low-pressure section 222 has: (a) an inner diameter that is larger than the inner diameter of a selected high-pressure section 229, and (b) an outer diameter that is the same as the outer diameter of the selected high-pressure section 229, and/or (vi) the low-pressure section 222 has a radial characteristic that is different from the radial characteristic associated with a selected high-pressure section (any one of the high-pressure sections 226, 228, 229): for example, the outer diameter of low-pressure section 222 may be 50 millimeters (mm) and the outer diameter of high-pressure section 226 may be 100 mm, and this configuration results in a difference of 50 mm between the diameters of the low-pressure section 222 and the high-pressure section 226.
FIGS. 12A and 12B depict the cross-sectional views of the system 10 of FIG. 11 according to the thirteenth non-limiting embodiment. FIG. 11 depicts the low-pressure section 222 and the high-pressure section 228. The low-pressure section 222 has: (a) an inner diameter that is smaller than the inner diameter of the high-pressure section 228, and (b) an outer diameter that is the same as the outer diameter of the high-pressure section 228. The first flange 102 is associated with the low-pressure section 222. The second flange 112 is associated with a selected one of the selected high-pressure sections 224, 226, 228 and/or 229 (depicted in FIG. 11). The second flange 112 is sealably engagable with the first flange 102. FIG. 12A depicts the valve 201 and the screw 18 in a retracted position 401. FIG. 12B depicts the valve 201 and the screw 18 in an extended position 402. A gap 410 is present between the screw 18 and the second liner 272 of the high-pressure section 228. According to a variant a band heater 422 is configured to be operatively engagable with the first flange 102 and the second flange 112. A locking pin 420 is used to lockably engage the flanges 102 and 112 together.
The description of the non-limiting embodiments provides examples of the present invention, and these examples do not limit the scope of the present invention. It is understood that the scope of the present invention is limited by the claims. The non-limiting embodiments described above may be adapted for specific conditions and/or functions, and may be further extended to a variety of other applications that are within the scope of the present invention. Having thus described the non-limiting embodiments, it will be apparent that modifications and enhancements are possible without departing from the concepts as described. It is to be understood that the non-limiting embodiments illustrate the aspects of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims. The claims themselves recite those features regarded as essential to the present invention. Preferable embodiments of the present invention are subject of the dependent claims. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims:
Patent Application
20090025901
