Patent Application
20080023862
A better understanding of the exemplary embodiments of the present invention (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the exemplary embodiments along with the following drawings, in which:
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.
Preferably, the passageway 130 is defined in a hot-runner manifold 190 (which is an example of a component of the system 100). According to a variant (not depicted), the passageway 130 is defined in: (a) a hot sprue (not depicted) and/or (b) a machine nozzle (not depicted) which are examples of components of the system 100. The molding material 120 is made to: (i) flow along the melt pathway 130 (in the manner known to those skilled in the art) and then (ii) strike and flow past the sensor 110. The flowing molding material 120 drags along a surface or a portion of the sensor 110 and imparts a drag force to the sensor 110. Responsive to the sensor 110 sensing the drag force imparted by the molding material 120 flowing along the melt pathway 130, the sensor 110, at least in part, adjusts flow of the molding material 120. The sensor 110 is movable responsive to the sensor 110 sensing drag from the molding material 120. As the sensor 110 moves relative to the melt pathway 130, movement of the sensor 110 causes flow of the molding material 120 to vary in the following manner: (i) if the molding material 120 has a low viscosity, the sensor 110 reacts to reduce the rate of flow of the molding material 120, and/or (ii) if the molding material 120 has a high viscosity, the sensor 110 reacts to increase the rate of flow of the molding material 120.
Preferably, the sensor 110 is placed in a drop of a multi-drop hot runner (the molding system 100 is the multi-drop hot runner), and the sensor 110 is used to control flow of the molding material made to flow through a drop of the multi-drop hot runner. The sensors 110 are placed in each drop and once the molding material flows, the hot runner becomes substantially balanced (as a result of using the sensors 110). A balanced hot runner has substantially equal pressure distribution in each drop (which ensures balanced part filling and reduces risk of material damage, and improves part-to-part consistency of a molded article). The hot-runner manifold 190 is hereafter referred to as the “manifold 190”. The multi-drop hot runner includes the manifold 190 that leads to multiple drops 192, 194 that in turn lead into a mold cavity defined by a mold (not depicted) that is operatively coupled to the manifold 190. In each selected drop of the manifold 190, a respective viscous-drag sensor is installed so that flow of the molding material 120 into the mold may become balanced by usage of the sensor 110.
Preferably, the sensor 110 includes a pathway blockage 150, a hollow tube 170 and an actuator 140, such as a spring 160 for example. The actuator 140 couples the pathway blockage 150 to the manifold 190. The spring 160 biases the pathway blockage 150 to constrict the melt pathway 130. The molding material 120 drags along and moves the pathway blockage 150 in a direction to either: (i) further open the melt pathway 130 if the viscosity of the molding material 120 is high or (ii) further close the melt pathway 130 if the viscosity of the molding material 120 is low. The amount of drag sensed by the sensor 110 is a function of: the viscosity of the molding material 120, the type of material that the sensor 110 is made from and/or the type of surface finish of the sensor 110 that comes into contact with the molding material 120. The pathway blockage 150 includes a hollow tube that is receivable in the melt pathway 130 (preferably the blockage 150 is receivable in the drop 192). The pathway blockage 150 also defines a portal 182. The hollow tube 170 receives the pathway blockage 150. The hollow tube 170 defines a portal 180 that is closable and openable by the pathway blockage 150. The degree to which the portal 180 and the portal 182 become aligned or misaligned permits reduced flow or increased flow of the molding material 120. Responsive to the sensor 110 sensing viscous-drag force, the actuator 140 actuatably moves the sensor 110 to adjust or amend blockage of the pathway 130 so that flow of the molding material 120 through the melt pathway 130 varies.
The system 200 is depicted as a hot-runner system (sometimes also referred to as a runner or a runner assembly or a runner sub-system) for use with an injection molding system or for use with any type of molding system. A molding material 220 is made to travel along a melt pathway 230, which is defined by the system 200 (specifically, the pathway 230 is defined by the manifold 290), over to a bore 232 of a nozzle 218 (the nozzle 218 is positioned in a drop 222). The molding material 220 travels along the bore 232 of the nozzle 218 and into a gate 221 and then into a mold cavity 224. The mold cavity 224 is defined by mold portions 226, 228. The manifold 290 distributes the molding material 220 to a plurality of drops, but only the drop 222 is depicted to ease description of the second exemplary embodiment. Although a hot runner system is depicted in which plastic-based melt is injected into the mold cavity 224, other types of injection systems may also use the second exemplary embodiment in which it is useful to balance the rate of flow of molding material (metal-based, plastic-based, fiber composite, etc) through multiple drops. A single gate, single cavity system is depicted. However, according to a variant, a multi-cavity system is used.
A valve pin 212 is used to control (start and stop) flow of the molding material 220 into the gate 221. A viscous-drag sensor 210 (hereafter referred to as the “sensor” 210) is used to balance flow between multiple drops (not depicted). The sensor 210 includes a body 214 and a pathway blockage 250. The body 214 and the pathway blockage 250 are integrally formed (alternatively, the pathway blockage 250 attaches to the body 214). The pathway blockage 250 is configured to be wider than the body 214 in order to restrict flow of molding material 220 in the bore 232. The body 214 and pathway blockage 250 are both of hollow construction so that the body 214 and the pathway blockage 250 receive the valve pin 212, and in this manner the valve pin 214 operates independently of the sensor 210. The sensor 210 may assume intermediate positions between a fully-open position and a fully-closed position in order to increase or decrease the rate of flow of the molding material 220 (while the valve pin 214 displaced away from the gate 221). The pathway blockage 250 includes a tapered portion 238 that forms a gap 280 with a surface 244 of the bore 232 of the nozzle 218. The size of the gap 280 increases or decreases as the viscous drag-sensor 210 becomes displaced due to the sensor 210 responding to drag from the molding material 220, so that flow of molding material 220 to the gate 221 increases or decreases. Displacement of the sensor 210 is achieved when the molding material 220 flows over the body 214 and the pathway blockage 250; the molding material 220 imparts a viscous drag force to the body 214 and the pathway blockage 250. If the molding material 220 has a high-viscosity, a greater drag force is imparted to the sensor 210 and in turn, a greater displacement of the sensor 210 is achieved and gap 280 is widened. Once the gap 280 is widened, the flow rate of the molding material 220 increases through the bore 232 allowing additional molding material 220 to reach the gate 221. If the molding material 220 has a low-viscosity or is relatively thin, a smaller drag force is imparted to the sensor 210 and in turn, a smaller displacement of the sensor 210 is achieved and the gap 280 is decreased in size. Once the gap 280 is decreased in size, the flow rate of the molding material 220 decreases through the melt pathway 230 allowing less molding material 220 to reach the gate 221.
Preferably, both the valve pin 212 and the sensor 210 are displaceable independent of each other. The valve pin 212 controls when flow of molding material 220 occurs while the viscous drag sensor controls the rate of flow of the molding material 220 into the cavity 224. Both the valve pin 212 and the sensor 210 are controllable by independent actuation mechanisms that are placed in a single, simple location to save space and cost for fabrication. The valve pin actuator 242 is preferably mounted in a plate 246. The valve pin actuator 242 is a pneumatic actuator; however, hydraulic or electronic actuators may be used. The actuator 242 includes a pneumatic circuit that has a movable piston 248 in which the valve pin 212 is threadably mounted at a mounting position 252. According to a variant, the pneumatic circuit may be located below the piston 248 asopposed to above as depicted in
A molding material 320 is made to travel along a melt pathway 330 that is defined by the system 300. Preferably, the pathway 330 is defined by a manifold 390. A viscous-drag sensor 310 (hereafter referred to as the “sensor 310”) is positionable in the melt pathway 330. The sensor 310 includes a pathway blockage 350 and an actuator 340 that is attached to a back side of the pathway blockage 350 (hereafter referred to as the “blockage” 350). The back side of the blockage 350 is abutable against and is slidable along an inner wall of the melt pathway 330. A front side of the blockage 350 faces the molding material 320. The actuator 340 is preferably a leaf spring 360. The leaf spring 360 is received into a recess or a hole defined in the manifold 390 and the recess extends from the inner wall of the melt pathway 330 into the interior of the manifold 390. The pathway blockage 350 includes a tapered portion 338 (which may also be called a wedge). A gap 380 if formed between the tapered portion 338 and a surface 344 of the pathway 330 (the surface 344 is located opposite of the tapered portion 338). The surface 344 forms a corner section of the pathway 330. The size of the gap 380 increases or decreases as the sensor 310 is displaced (that is, slides along the pathway 330) due to the sensor 310 responding to drag from the molding material 320. Displacement (or movement) of the sensor 310 is achieved when the molding material 320 flows over the tapered portion 338 and then drags the sensor 310 along. In this manner, the molding material 320 imparts a viscous drag force to the tapered portion 338. If the molding material 320 has a high-viscosity, a greater drag force is imparted on the tapered portion 338 and in turn, a greater displacement of the sensor 310 is achieved and as a result, the gap 380 is widened. Once the gap 380 is widened, the flow rate of the molding material 320 increases through the melt pathway 330. If the molding material 320 has a low-viscosity or is relatively thin, a smaller drag force is imparted to the sensor 310 and in turn, a smaller displacement of the sensor 310 is achieved and the gap 380 is decreased in size. Once the gap 380 is decreased in size, the flow rate of the molding material 320 decreases through the melt pathway.
The actuator 340 is configured to operate in positions between a first manifold wall 356 and a second manifold wall 358 (the walls 356, 358 define the recess in which the leaf spring 360 resides); the two manifold walls 356, 358 preferably define an acute angle between themselves. The leaf spring 360 is attached to the location where the two walls 356, 358 meet. The leaf spring 360 biases the pathway blockage 350 to move toward wall 356 and away from wall 358. The molding material 320 moves and drags along the pathway blockage 350 in a direction to either: (i) further open (or widen) the gap 380 if the viscosity of the molding material 320 is high or (ii) further close (or narrow) the gap 380 if the viscosity of the molding material 320 is low. Responsive to the sensor 310 sensing viscous-drag force, the leaf spring 360 actuatably moves the sensor 310 to amend the gap 380 so that flow of the molding material 320 through the mold pathway 330 may vary.
According to a variant, the sensor 310 also includes a flow-check arm 355 pivotably attached to the pathway blockage 350. The flow check arm 355 is configured to continuously abut a pathway wall 359 in order to prevent molding material 320 flowing over the tapered surface 338 (and to the rearward portion of the pathway blockage 350) from seeping behind the pathway blockage 350 and collecting in a crevice 357.
A viscous-drag sensor 410 (hereafter referred to as the “sensor 410”) is interactable with a molding material 420 that is flowable along a melt pathway 430 of the system 400, past a gate 492 that leads into a mold cavity of a mold (not depicted). The sensor 410 includes a body 411 and an arm 413 that is rotatably spring biased relative to the body 411 at a biasing point 415. The biasing point 415 is located on an end of the body 411. The sensor 410 is positioned along a wall 417 of the melt pathway 430. The arm 413 is used to control (adjust) flow of the molding material 420. The body 411 is flat, is abutable against the wall 417 and is slidably retained along the wall 417 so that the body 411 may reciprocate. A groove 419 is defined in the wall 417 and the groove 419 is used to limit sliding of the body 411 between a high-flow position and a low-flow position, and to retain the body 411 adjacent to the wall 417 at all times of operation. The arm 413 extends from the coupling point 415 and into the pathway 430 so as to facilitate flow control of the molding material 420. A gap 480 is defined between an end of the arm 413 (that is, the end opposite from the point 415) and a surface 444 of a manifold 490 of the system 400. The size of the gap 480 increases or decreases as the arm 413 is made to rotate as a result of the sensor 410 responding to drag from the molding material 420. Flow control of the molding material 420 is achieved as follows: (i) if the molding material 420 has a high viscosity (and is made to flow over the body 411), the molding material 420 imparts a viscous drag force to the body 411 and in turn the body 411 is made to translate sufficiently enough so as to rotate the arm 413 (and store energy in a spring-biasing mechanism 440). The method of rotation of the arm 413 is described below. Once the arm 413 rotates, the gap 480 is widened. Once the gap 480 is widened, the flow rate of the molding material 420 increases, and (ii) if the molding material 420 has a low viscosity or is relatively thin, a smaller drag force is imparted to the body 411 and in turn the spring-biasing mechanism 440 (that couples the arm 413 to the body 411) urges the body 411 to slide away from the arm 413 and the gap 480 is decreased in size. Once the gap 480 is decreased in size, the flow rate of the molding material 420 decreases through the melt pathway 430.
The spring-biasing mechanism 440 (hereafter referred to as the “actuator” 440). The actuator 440 couples (spring biases) the body 411 to the arm 413 at the coupling point 415. The actuator 440 is configured to operate in relation to the body 411 sliding due to the viscous drag force imparted by the molding material 420. The actuator 440 is preferably a torsional spring 460. Responsive to the body 411 sliding, the torsional spring 460 receives an input torque. The input torque exerted on the torsional spring 460 is achieved via a linkage 421 that links the body 411 to the torsional spring 460. One side of the linkage 421 is attached to the body 411 while the other side is attached to the torsional spring 460. As the body 411 slides due to the viscous drag force imparted to the body 411 by the molding material 420, the linkage 421 slides along with the body 411. The sliding of linkage 421 is opposed by the torsional spring 460 which is rigidly connected to the point 415 and not allowed to rotate freely (the point 415 is located at an end of the arm 413). The opposition of sliding in turn produces a torque on the torsional spring 460. The only torque exerted on the torsional spring 460 prior to the linkage 421 exerting the input torque is the molding-material-flow torque 457 caused by the molding material 420 flowing past the arm 413 (which is reigidly attached to the spring 460 at the coupling point) and inducing a force on the arm 413 and in turn inducing a torque on the torsional spring 460. Since: (i) a greater net torque is placed on the torsional spring 460 due to both the linkage 421 and (ii) the molding material 420 and the torsional spring 460 is not able to withstand a greater net torque without rotating, a rotation of the torsional spring 460 and the arm 413 will result. The rotation of arm 413 increases the size of gap 480, allowing more molding material 420 to travel to the drop 492. If the molding material 420 has a low viscosity, then the viscous drag force would not be as great on the body 411. The lack of force (that is force imparted to the body 411) due to a lower viscosity of the molding material 120 will result in the body 411 sliding back to its starting, or low-flow position due to the torsional spring exerting a stored torque to the linkage 421 and in turn causing the linkage 421 and body 411 to slide back. The lack of viscous-drag force would cause the net torque to decrease and in turn cause the arm 413 to rotate to constrict the gap 480 and allow less molding material 420 to flow through the melt pathway 430 to the drop 492. The torsional spring 460 spring biases the arm 413 to constrict the gap 480. The molding material 420 drags along and moves the body 411 in a direction to either: (i) further open the gap 480 if the viscosity of the molding material 420 is high or (ii) further close the gap 480 if the viscosity of the molding material 420 is low. Responsive to the sensor 410 sensing viscous-drag force, the torsional spring 460 actuatably rotates the arm 413 to amend (that is, widen or narrow) the gap 480 so that flow of the molding material 420 through the mold pathway 430 varies.
As molding material 520 is made to flow along the melt pathway 530 toward the gate 592, the molding material 520 encounters the screw 511 and flows along the screw flights 515 in order to travel past the screw 511 and then enter the gate 592. In doing so, the molding material 520 exerts a viscous-drag force to the flights 515. The viscous drag force imparted to the screw 511 causes the screw 511 to rotate (counter clockwise, for example).
The sensor 510 senses the drag force and counters the drag force by adjusting the relative rate of rotation of the sensor 510 with the manifold 590. The screw 511 and the shaft 513 rotate at a constant torque in an opposing direction of the flow rotation of the molding material 520. The actuator 540 creates: (i) a faster counter rotation to flow direction once a low-viscosity molding material 520 passes over the sensor 510, and (ii) a slower counter rotation to flow direction once a high-viscosity molding material 520 passes over the sensor 510.
The actuator 540 is mounted in the manifold 590. The actuator 540 is preferably a constant torque electric motor 594 (hereafter referred to as the “motor 594”); according to a variant, the motor 594 includes a hydraulic or a pneumatic motor. The motor 594 is used to rotate the shaft 513 and rotation of the shaft 513 causes further rotation of the screw 511 (which is rigidly attached or coupled to the shaft 513). The motor 594 rotation direction is in the opposite direction of the rotation induced on the screw 511 by the viscous drag force. As the molding material 520 flows past flights 515, the molding material 520 imparts a viscous drag force to the screw 511 creating a rotation in the flow direction of the molding material. Responsive to the screw 511 rotating due to the viscous drag force imparted to the screw 511 by the molding material 520, the motor 594 creates an opposite direction of rotation in order to counter the flow of the molding material 520. The motor 594 creates rotation at a constant torque so as to vary speed of rotation with different drag conditions. If a high viscosity molding material 520 flows past the screw 511, (i) a high viscous drag force will be imparted on the screw 511 and (ii) the motor 594 will rotate at a constant torque but slower speed due to the high viscous drag force resulting in a higher flow rate of molding material 520 past the screw 511. If a low viscosity molding material 520 flows past the screw 511, (i) a low viscous drag force will be imparted on the screw 511 and (ii) the motor 594 will rotate at a constant torque but higher speed due to the low viscous drag force resulting in a lower flow rate of molding material 520 past the screw 511. Responsive to the sensor 510 sensing viscous-drag force, the motor 594 actuatably rotates the screw 511 to amend (that is, increase or decrease) the molding material 520 flow rate so that flow of the molding material 520 through the mold pathway 530 varies. The sensor 500 creates a self-priming system, causing heterogeneous (at least in part) molding material (in terms of viscosity) to flow at similar rates from each drop of the molding system and this provides and improved balancing of the molding system.
Preferably, the sensor 610 includes a screw 611 and a shaft 613 that is connected or coupled to the screw 611. The shaft 613 and the screw 611 are axially aligned with each other once they are connected together. The screw 611 is cylindrical and has a set of helical flights 615 winding along a longitudinal axis extending through the screw 611. Preferably, the screw 611 has a constant pitch and a constant diameter. According to a variant, the screw 611 has a non-constant pitch; according to another variant, the screw 611 has a variable pitch and a variable diameter. The flight diameter of the helical flights 615 is preferably smaller than the diameter of the melt pathway 630 (but reaching close to the side walls of the pathway 630). In this manner, the molding material 620 is made to flow and interact with the sensor 610 and does not (preferably) substantially bypass the sensor 610. The last flight of screw 611 (located closest to the gate 692) is configured to define an exit 616 for permitting the molding material 620 to travel therethrough. Adjacent to the exit 616 of the screw 611 (located on a manifold wall 617) is a blocking member 650. The blocking member 650 is rigidly attached to (and extending from) the manifold wall 617. The member 650 is offset from the screw 611 and is positioned so as to be in-line with the exit 616 (once the screw 615 is rotated just so). A gap 680 is defined between the blocking member 650 and the exit 616. The gap 680 is configured to provide a path for molding material 620 to pass therethrough on the way to the gate 692. The size of the gap 680 increases or decreases as the sensor 610 becomes rotated due to the sensor 610 responding to drag imparted to the sensor 610 from the molding material 620 so that flow of molding material 620 to the gate 692 may increase or decrease. Rotational displacement of the sensor 610 is achieved when the molding material 620 flows over the flights 615 and then imparts a viscous drag force to flights 615 of the screw 611. If the molding material 620 has a high-viscosity, a greater drag force is imparted to the sensor 610 and in turn a greater radial displacement of the sensor 610 is achieved so that the gap 680 is widened due to misalignment of the blocking member 650 elative to the exit 616. Once the gap 680 is widened, the flow rate of the molding material 620 increases through the screw 611 allowing additional (or more) molding material 620 to reach the gate 692. If the molding material 620 has a low-viscosity or is relatively thin, a smaller drag force is imparted to the sensor 610 and in turn a smaller displacement of the sensor 610 is achieved so that the gap 680 is decreased in size due to close alignment of the blocking member 650 with the exit 616 (so as to increase blocking of the exit 616). Once the gap 680 is decreased in size, the flow rate of the molding material 620 decreases through the melt pathway 630 allowing less molding material 620 to reach the gate 621.
An actuator 640 is coupled to the shaft 613. The actuator 640 is used to bias rotation (clockwise, for example) of the shaft 613 and the screw 611 in order to control alignment of the pathway blockage 650 relative to the exit 616 (the size of the gap 680). The actuator 640 is mounted to a side wall of the pathway 630 of the manifold 690. The actuator 640 is preferably a torsional spring 660 (hereafter referred to as the “spring 660”). The spring 660 is used to bias rotational movement of the shaft 613 and of the screw 611. The spring 660 biases the exit 616 of the screw 611 to align with the pathway blockage 650. The spring 660 biasing direction is in the opposite direction of rotational displacement induced on the screw 611 by the viscous drag force. As the molding material 620 flows past flights 615, the molding material 620 imparts a viscous drag force to the screw 611 thus creating misalignment of the pathway blockage 650 with the exit 616 and thus creating a larger gap 680. Responsive to the screw 611 rotating due to the viscous drag force imparted to the screw 611 by the molding material 620, the spring 660 stores potential energy and creates a biasing force in the opposite direction of rotation in order to reduce the rotational displacement (misalignment) created by the viscous drag force and to control the size of gap 680. The spring 660 creates different rotational forces so as to vary the size of the gap 680 with different drag conditions. If a high-viscosity molding material 620 flows past the screw 611, (i) a high viscous drag force will be imparted to the screw 611 and (ii) the spring 660 will store more potential energy, and the spring 660 biases the rotational displacement (misalignment) of the screw 611 by a smaller amount which results in a larger gap 680 and a higher flow rate of molding material 620 past the screw 611. If a low-viscosity molding material 620 flows past the screw 611, (i) a low viscous drag force will be imparted on the screw 611 and (ii) the spring 660 will store less potential energy, and the spring 660 biases the rotational displacement (misalignment) of the screw 611 by a larger amount which results in a smaller gap 680 and a lower flow rate of molding material 620 past the screw 611. Responsive to the sensor 610 sensing viscous-drag force, the spring 660 actuatably rotates the screw 611 to amend (that is, increase or decrease) the size of the gap 680 so that flow of the molding material 620 through the mold pathway 630 varies.
Preferably, the sensor 710 includes a body 711, a pathway blockage 750 separate from the body 711, and a fluid channel 727 configured to receive the body 711 and to receive the pathway blockage 750. The body 711 is configured to be flat and to be abutable against a bottom-manifold wall 717 of the melt pathway 730. The body 711 is slidably retained along the bottom-manifold wall 717 so that the body 711 may reciprocate within the fluid channel 727. A groove (or recess) 719 is defined in the bottom-manifold wall 717. The groove 719 is used to limit sliding of the body 711 between a high-flow position and a low-flow position. The fluid channel 727 has: (i) a first-channel end 729 from which the body 711 enters (beginning in the melt pathway 730 at a first location adjacent to the bottom manifold wall 717), and (ii) a second-channel end 731 ending in the melt pathway 730 at a second location offset from the first location. The second location is downstream and closer to the gate 792 than the first location. Defined between the two channel ends 729, 731 is a fluid channel 727 extending through the manifold 790 (preferably extending adjacent to the melt pathway 730). A portion of the body 711 is configured to retainably slide inside the first channel end 729 of the fluid channel 727. The portion of the body 711 that is not inside the first channel end 729 protrudes out of the fluid channel 727 and extends into the melt pathway 730 where it is interactable with the molding material 720 passing through the pathway 730.
The pathway blockage 750 is configured to have a first side 733 and a second side 735 that is offset from the first side. The blockage 730 defines a passage 737 between the sides 733, 735. The molding material 720 travels through the passage 737. The pathway blockage 750 is slidably positionable inside the second channel end 731 of the fluid channel 727. The first side 733 of the pathway blockage 750 is slidably retained (at least in part) within the second channel end 731. The pathway blockage 750 is preferably perpendicular in orientation relative to the flow of the melt pathway 730. The second channel end 731 ends at a first manifold wall 753 and the first manifold wall 753 defines a portion of the melt pathway 730. On the opposite side of the first manifold wall 753 is a second manifold wall 755 defining another portion of the melt channel 730. The second manifold wall 755 contains a bore 757 configured to be: (i) preferably extending perpendicularly relative to the melt pathway 730 and into the manifold 790 and (ii) in alignment with the second channel end 731. The bore 757 houses: (i) an actuator 740 and (ii) the second side 735 of the pathway blockage 750. The actuator 740 is configured to act on the second side 735 in the bore 757 (at a location inside the manifold 790), whereas the second side 735 of the pathway blockage 750 is: (i) slidably retained within the bore 757 (at least in part), and (iii) configured to extend into the melt pathway 730. The pathway blockage 750 is slidably retained between walls of the melt pathway by having: (i) the first side 733 retained by the second channel end 731 located on the first manifold wall 753 and (ii) the second side 735 retained by the bore 757 located on the second manifold wall 755. The passage 737 is configured to be substantially parallel with the melt pathway 730 in which the passage 737 provides a path for the molding material 720 to pass therethrough on the way to the gate 792. Since the two sides 733, 735 of the pathway blockage 750 are slidably retained by channels in the manifold 790, the passage 737 is allowed to align or misalign with the melt pathway 730 depending on the position of the pathway blockage 750. The outline of the passage 737 is preferably rectangular, the size of the rectangle is preferably equal to that of the melt pathway 730 in order to allow melt flow therethrough upon perfect alignment with the melt pathway 730. According to a variant, the passage 737 is square shaped; according to another variant the passage 737 is circular shaped.
The fluid channel 727 preferably contains an incompressible fluid 767 (hereafter referred to as the “fluid 767”) such as a hydraulic fluid for example. The incompressible fluid 767 is used to establish fluid communication between the body 711 and the first side 733 of the pathway blockage 750. According to a variant, the fluid 767 is a compressible fluid. The fluid 767 allows for a force to be transmitted between the body 711 and the pathway blockage 750. The size of the passage 737 increases or decreases as the sensor 710 becomes translated due to the body 711 responding to drag imparted to the body 711 from the molding material 720 so that flow of molding material 720 to the gate 792 may be controlled (increased, decreased, etc). Translational displacement of the sensor 710 is achieved when the molding material 720 flows over the body 711 and then imparts a viscous drag force to the body 711. The viscous drag force is transmitted from the body 711, through the incompressible fluid 767 and to the pathway blockage 750, creating translational motion of the sensor 710. If the molding material 720 has a high viscosity, a greater drag force is imparted to the sensor 710 and in turn a greater translational displacement of the sensor 710 is achieved so that the passage 737 is widened due to close alignment of the pathway blockage 750 relative to the melt pathway 730. Once the passage 737 is widened, the flow rate of the molding material 720 increases through the pathway blockage 750 allowing additional molding material 720 to reach the gate 792. If the molding material 720 has a low viscosity or is relatively thin, a smaller drag force is imparted to the sensor 710 and in turn a smaller displacement of the sensor 710 is achieved so that the passage 737 is decreased in size due to misalignment of the pathway blockage 750 with the melt pathway 730 (so as to increase blocking of the passage 737). Once the passage 737 is decreased in size, the flow rate of the molding material 720 decreases through the melt pathway 730 allowing less molding material 720 to reach the gate 792.
The actuator 740 is coupled to (or acts on) the second side 735 of pathway blockage 750. The actuator 740 is used to bias translational motion (toward the left side of
Preferably, the sensor 810 includes: (i) a hollow housing 888 (preferably, tubular in shape) that is received into the melt pathway 830 (and is secured to the pathway 830), (ii) a body 811 that is slidable in a fluid channel 827 that is defined by the hollow housing 888, and (iii) a pathway blockage 850. The hollow housing 888 (hereafter referred to as the “housing 888”) has a cross-sectional shape that is substantially similar to the cross-sectional shape of the melt pathway 830 in order to be sealably received in the melt pathway 830 at a location upstream of the gate 892. The housing 888 has an entrance 889 that allows the molding material 820 to enter and to travel through the housing 888. The housing 888 also has an exit 895 that allows the molding material 820 to exit back into the melt pathway 830 downstream of the entrance 889 on its way to the gate 892. Preferably, a set of threads 852 is located on the outside of the housing 888 in order to threadably tighten the housing 888 to the melt pathway 830. According to a variant, the housing 888 is press fit into the melt pathway 830; according to another variant, the housing 888 is attached to the melt pathway 830. The housing 888 is configured to: (i) allow the molding material 820 to pass therethrough from the entrance 889 to the exit 895 by forming a continuation of the melt pathway 830 and (ii) contain the body 811, the fluid channel 827 and the pathway blockage 850 between the entrance 889 and the exit 895.
The body 811 is configured to be flat and abutable against an inner housing wall 817 of the housing 888. The body 888 is slidably retained along the inner housing wall 817 so that the body 811 may reciprocate along the direction of travel of the molding material 820. A groove 819 is defined in the inner housing wall 817. The groove 819 is used to (i) slidably retain the body 811 and (ii) limit sliding of the body 811 between a high-flow position and a low-flow position. The fluid channel 827 has: (i) a first channel end 829 beginning in the housing 888 at a first location adjacent to the inner housing wall 817 and (ii) a second channel end 831 ending in the housing 888 at a second location. The first location is positioned closer to the entrance 889, while the second location is positioned closer to the exit 895. The two channel ends 829, 831 define the fluid channel 827 therebetween aligned adjacent to the mold pathway 830 inside the housing 888. A portion of the body 811 is configured to retainably slide inside the first channel end 829. The portion of the body 811 not inside the first channel end 829 protrudes out of the fluid channel 827 and extends into the inside of the housing 888, towards the entrance 889, where the body 811 interacts with the molding material 820 entering the entrance 889 and passing therethrough.
The pathway blockage 850 is configured to have a first side 833 and a second side 835. A space between the two sides 833, 835 defines a passage 837 for molding material 820 to travel therethrough. The pathway blockage 850 is positionable inside the housing 888 adjacent to the second channel end 831 of the fluid channel 827. The first side 833 of the pathway blockage 850 is slidably retained by the second channel end 831. The pathway blockage 850 is preferably perpendicular in orientation relative to the housing 888. The second channel end 831 ends at a first housing inner surface, the first inner surface defines a portion of the melt pathway 830 traveling through the housing 888. On the opposite side of the first housing inner surface is a second inner surface defining another portion of the melt channel 830 traveling through the housing 888. The second surface contains a bore 857 configured to be: (i) preferably extending perpendicularly to the melt pathway 830 (the bore 857 extending into the housing 888) and (ii) in the same vertical position in the melt pathway 830 as the second channel end 831. The bore 857 houses an actuator 840 and the second side 835 of the pathway blockage 850. The actuator 840 is configured to be behind the second side 835 in the bore 857 at a location further inside the housing 888 whereas the second side 835 of the pathway blockage 850 is slidably retained by the bore 857 and is configured to extend into the melt pathway 830. The pathway blockage 850 is slidably retained between walls of the melt pathway by having (i) the first side 833 retained by the second channel end 831 located on the inner surface and (ii) the second side 835 retained by the bore 857 located on the second inner surface. The passage 837 is configured to be substantially parallel with the melt pathway 830; the passage 837 provides a path for molding material 820 to pass therethrough on its way from the entrance 889 of the housing 888 to the exit 895. Since the two sides 833, 835 of the pathway blockage 850 are slidably retained by channels in the housing, the passage 837 is allowed to align or misalign with the melt pathway 830 depending on the position the pathway blockage 850. The passage 837 outline is preferably rectangular shaped and the size of the rectangle is preferably equal to that of the melt pathway 830 in order to allow melt flow therethrough upon perfect alignment with the melt pathway 830. According to a variant, the passage 837 is square shaped; according to another variant the passage 837 is circular shaped.
The fluid channel 827 preferably contains an incompressible fluid 867 (hereafter referred to as the “fluid 867”) in order to establish fluid communication between the body 811 and the first side 833 of the pathway blockage 850. According to a variant, the fluid 867 is a compressible fluid. The fluid 867 allows for a force to be transmitted between the body 811 and the pathway blockage 850. The size of the passage 837 increases or decreases as the sensor 810 becomes translated due to the body 811 responding to drag imparted to the body 811 from the molding material 820 so that flow of molding material 820 to the gate 892 may increase or decrease. Translational displacement of the sensor 810 is achieved when the molding material 820 flows over the body 811 and then imparts a viscous drag force to the body 811. The viscous drag force is transmitted from the body, through the incompressible fluid and to the pathway blockage 850, creating translational motion at a distance from the viscous drag sensing point. If the molding material 820 has a high viscosity, a greater drag force is imparted to the sensor 810 and in turn a greater translational displacement of the sensor 810 is achieved so that the passage 837 is widened due to close alignment of the pathway blockage 850 relative to the melt pathway 830. Once the passage 837 is widened, the flow rate of the molding material 820 increases through the pathway blockage 850 allowing additional molding material 820 to reach the gate 892. If the molding material 820 has a low viscosity or is relatively thin, a smaller drag force is imparted to the sensor 810 and in turn a smaller displacement of the sensor 810 is achieved so that the passage 837 is decreased in size due to misalignment of the pathway blockage 850 with the melt pathway 830 (so as to increase blocking of the passage 837). Once the passage 837 is decreased in size, the flow rate of the molding material 820 decreases through the melt pathway 830 allowing less molding material 820 to reach the gate 892.
The actuator 840 is coupled to the second side 835 of pathway blockage 850. The actuator 840 is used to bias translational motion (toward the left side of
A viscous-drag sensor 910 (hereafter referred to as the “sensor 910”) is interactable with a molding material 920 that is flowable along a melt pathway 930 of the system 900. The sensor 910 is positioned in the melt pathway 930. The melt pathway 930 extends through a manifold 990 and ends at a gate 992 that leads into a mold cavity defined by a mold (not depicted). The location of the sensor 910 in the melt pathway 930 is such that flow characteristics (of the molding material 920) are adjustable or controllable prior to the molding material 920 reaching the gate 992.
Preferably, the sensor 910 includes a magnetic body 911 (hereafter referred to as the “body 911”). The body 911 is configured to be flat and abutable against a first manifold wall 917 in the melt pathway 930. The body 911 is slidably retained along the first manifold wall 917 so that the body 911 may reciprocate. A groove 919 is defined in the first manifold wall 917 and the groove 919 is used to limit sliding of the body 911 between a high-flow position and a low-flow position. The body 911 is preferably made of a magnetic material having two magnetic poles (a body first pole 901 and a body second pole 902). The body first pole 901 and second pole 902 are: (i) opposite polarities such as north and south and (ii) spaced apart and located on opposite ends of the body 911. According to a variant, the body 911 is an electromagnet having two electrically-induced magnetic poles. The body first pole 901 is located downstream of the body second pole 902. A bore 957, located on a second manifold wall 919, is configured to slidably retain a pathway blockage 950 as well as an actuator 940. The bore 957 is preferably perpendicular in orientation relative to the melt pathway 930. The second manifold wall 919 is located opposite of the first manifold wall 917 and forms the second side of a melt pathway 930. Together, the first and second manifold walls 917, 919 form a portion of the melt pathway 930 for the molding material 920 to travel through on its way to the gate 992. The bore 957 is located on a level identical to that of the body 911. The longitudinal axis of the body 911 is aligned with the longitudinal axis of the bore 957. The actuator 940 is located behind the pathway blockage 950 inside the bore 957 at a location further inside the manifold 990. The pathway blockage 950 is slidably retained by the bore 957 and is configured to partially extend into the melt pathway 930.
The pathway blockage 950 is a magnet having a block first pole 903 and a block second pole 904. The block first pole 903 extends into the melt pathway 930 in order to provide a restriction for flowing molding material 920; the size of the restriction depends on the viscosity of the molding material 920. The block second pole 904 is on the pathway blockage side located inside the bore 957 while the block second pole 904 is configured to magnetically interact with the actuator 940. Because the body 911 and the pathway blockage 950 are both magnets, they magnetically interact with each other. Movement of the body 911 due to the viscous drag force imparted on it causes flow of the molding material 920 to vary in the following manner: (i) if the molding material 920 has a low viscosity, the sensor 910 reacts to reduce the rate of flow of the molding material 920, and/or (ii) if the molding material 920 has a high viscosity, the sensor 910 reacts to increase the rate of flow of the molding material 920. In this manner, the molding material 920 is made to flow and interact with the sensor 910 and does not (preferably) substantially bypass the sensor 910. A gap 980 is defined between the body 911 and the pathway blockage 950. The gap 980 is configured to provide a path for molding material 920 to pass therethrough on the way to the gate 992. The size of the gap 980 increases or decreases as the sensor 910 becomes translated due to the body 911 responding to drag imparted to the body 911 from the molding material 920 so that flow of molding material 920 to the gate 992 may increase or decrease. Translational displacement of the sensor 910 is achieved when the molding material 920 flows over the body 911 and then imparts a viscous drag force to the body 911. If the molding material 920 has a high viscosity, a greater drag force is imparted to the body 911 and in turn a greater translational displacement of the body 911 is achieved. This greater translational displacement causes the body 911 to get closer to the pathway blockage 950. Since both the pathway blockage 950 and body 911 are magnets having opposite polarities facing each other, then the gap 980 is widened due to the force induced on the pathway blockage, causing it to slide into the bore 957 and decrease the restriction of molding material flow. Once the gap 980 is widened, the flow rate of the molding material 920 increases through the melt pathway 980 allowing additional molding material 920 to reach the gate 992. If the molding material 920 has a low viscosity or is relatively thin, a smaller drag force is imparted to the sensor 910 and in turn a smaller displacement of the sensor 910 is achieved. This smaller translational displacement induces a smaller force on the pathway blockage 950, failing to move it any further into the bore 957. The pathway blockage 950 remains protruding from the bore 957 creating (i) restriction of molding material 920 flow and (ii) a reduction in gap 980 size. Once the gap 980 is decreased in size, the flow rate of the molding material 920 decreases through the melt pathway 930 allowing less molding material 920 to reach the gate 921.
The actuator 940 is placed adjacent to the block second pole 904. The actuator 940 is used to bias translational motion (toward the left side of
Preferably, the sensor 1010 includes: (i) a hollow housing 1088 (preferably, tubular in shape) that is received into the melt pathway 1030 (and is secured to the pathway 1030), (ii) a body 1011 that is slidable in a channel 1027 that is defined by the hollow housing 1088, and (iii) a pathway blockage 1050 that is slidably mounted to the hollow housing 1088. The hollow housing 1088 (hereafter referred to as the “housing 1088”) has a cross-sectional shape that is substantially similar to the cross-sectional shape of the melt pathway 1030 in order to be sealably received in the melt pathway 1030 at a location upstream of the gate 1092. The housing 1088 has an entrance 1089 that allows the molding material 1020 to enter and to travel through the housing 1088. The housing 1088 also has an exit 1095 that allows the molding material 1020 to exit back into the melt pathway 1030 downstream of the entrance 1089 on its way to the gate 1092. A set of threads 1052 is located on the outside of the housing 1088 in order to threadably tighten or engage the housing 1088 to the melt pathway 1030. According to a variant, the housing 1088 is press fit into the melt pathway 1030; according to another variant, the housing 1088 is securely or fixedly attached to the melt pathway 1030. The housing 1088 is configured to: (i) allow the molding material 1020 to pass therethrough from the entrance 1089 to the exit 1095 by forming a continuation of the melt pathway 1030 and (ii) structurally position the body 1011, the fluid channel 1027 and the pathway blockage 1050 between the entrance 1089 and the exit 1095.
The body 1011 is configured to be flat and abutable against an inner housing wall 1017 of the housing 1088. The body 1088 is slidably retained along the inner housing wall 1017 so that the body 1011 may reciprocate along the direction of travel of the molding material 1020. A groove 1019 is defined in the inner housing wall 1017. The groove 1019 is used to (i) slidably retain the body 1011 and (ii) limit sliding of the body 1011 between a high-flow position and a low-flow position. The body 1011 is preferably made of a magnetic material having two magnetic poles (a body first pole 1001 and a body second pole 1002). The body first pole 1001 and second pole 1002 are: (i) opposite polarities such as north and south and (ii) spaced apart and located on opposite ends of the body 1011. According to a variant, the body 1011 is an electromagnet having two electrically-induced magnetic poles. The body first pole 1001 is located downstream of the body second pole 1002. The channel 1027 has: (i) a first channel end 1029 beginning in the housing 1088 at a first location adjacent to the inner housing wall 1017 and (ii) a second channel end 1031 ending in the housing 1088 at a second location. The first location is positioned closer to the entrance 1089, while the second location is positioned closer to the exit 1095. The two channel ends 1029, 1031 define the channel 1027 therebetween aligned adjacent to the mold pathway 1030 inside the housing 1088. A portion of the body 1011 is configured to retainably slide inside the first channel end 1029. The portion of the body 1011 not inside the first channel end 1029 protrudes out of the fluid channel 1027 and extends into the inside of the housing 1088, towards the entrance 1089, where the body 1011 interacts with the molding material 1020 entering the entrance 1089 and passing therethrough.
Preferably, the pathway blockage 1050 includes a magnet (or magnetic material), the pathway blockage 1050 having a first block pole 1033 and a second block pole 1035. A space between the two poles 1033, 1035 define a passage 1037 for molding material 1020 to travel therethrough. The pathway blockage 1050 is positioned inside the housing 1088 adjacent to the second channel end 1031 of the channel 1027. The first block pole 1033 of the pathway blockage 1050 is slidably retained in the second channel end 1031. The pathway blockage 1050 is preferably perpendicular in orientation relative to the housing 1088. The second channel end 1031 ends at a first housing inner surface, the first inner surface defines a portion of the melt pathway 1030 traveling through the housing 1088. On the opposite side of the first housing inner surface is a second inner surface defining another portion of the melt channel 1030 traveling through the housing 1088. The second surface contains a bore 1057 that preferably extends (i) perpendicularly to the melt pathway 1030 (the bore 1057 extending into the housing 1088) and (ii) in the same vertical position in the melt pathway 1030 as the second channel end 1031. The bore 1057 houses an actuator 1040 and the second block pole 1035 of the pathway blockage 1050. The actuator 1040 is positioned behind the second block pole 1035 in the bore 1057 at a location further inside the housing 1088, whereas the second block pole 1035 of the pathway blockage 1050 is (i) slidably retained by the bore 1057 and (i) extends into the melt pathway 1030. The pathway blockage 1050 is slidably retained between walls of the melt pathway by having (i) the first block pole 1033 retained by the second channel end 1031 located on the inner surface and (ii) the second block pole 1035 retained by the bore 1057 located on the second inner surface. The passage 1037 is substantially parallel with the melt pathway 1030; the passage 1037 provides a path for molding material 1020 to pass therethrough on its way from the entrance 1089 of the housing 1088 to the exit 1095. Since the two block poles 1033, 1035 of the pathway blockage 1050 are slidably retained by channels in the housing, the passage 1037 is allowed to align or misalign with the melt pathway 1030 depending on the position the pathway blockage 1050. The passage 1037 outline is preferably rectangular shaped and the size of the rectangle is preferably equal to that of the melt pathway 1030 in order to allow melt flow therethrough upon perfect alignment with the melt pathway 1030. According to a variant, the passage 1037 is square shaped; according to another variant the passage 1037 is circular shaped.
The channel 1027 preferably contains an empty space (or channel) 1067 (hereafter referred to as the “space 1067”) that is defined by a tube. The tube and the space 1067 allow the body 1011 to be retainably, slidably movable along the wall 1017 so that the poles 1001, 1033 may be brought movably interactable relative to each other. The size of the passage 1037 increases or decreases as the body 1011 of the sensor 1010 becomes translated due to the body 1011 receiving (responding to) drag imparted by the molding material 1020, so that flow of molding material 1020 to the gate 1092 may be increased or decreased. Translational displacement of the sensor 1010 is achieved when the molding material 1020 flows over the body 1011 and then imparts a viscous drag force to the body 1011 causing the body 1011 to slide upwardly into the first channel end 1029 and closer to the second channel end 1031 (which contains the blockage 1050). Because the body 1011 and the pathway blockage 1050 include magnets, they are magnetically interactable with each other. Since the body first pole 1001 and the first block pole 1033 are preferably similar (that is, they have the same magnetic polarity), then movement of the body 1011 towards the pathway blockage 1050 will create a magnetic repulsion force that travels through the space 1067. Once the body 1011 is translated further into channel 1027 due to the viscous drag force imparted to the body 1011 by the molding material 1020, the pathway blockage 1050: (i) feels or senses a magnetic force on the first block pole and (ii) adjusts its position by translating in the housing 1088 and creating alignment or misalignment of the passage 1037 with the melt channel 1030. Movement of the body 1011 due to the viscous drag force imparted on it causes flow of the molding material 1020 to vary in the following manner: (i) if the molding material 1020 has a low viscosity, the sensor 1010 reacts to reduce the rate of flow of the molding material 1020, and/or (ii) if the molding material 1020 has a high viscosity, the sensor 1010 reacts to increase the rate of flow of the molding material 1020. In this manner, the molding material 1020 is made to flow and interact with the sensor 1010 and does not (preferably) substantially bypass the sensor 1010. If the molding material 1020 has a high viscosity, a greater drag force is imparted to the sensor 1010 and in turn a greater translational displacement of the sensor 1010 is achieved so that the passage 1037 is widened due to close alignment of the pathway blockage 1050 relative to the melt pathway 1030. Once the passage 1037 is widened, the flow rate of the molding material 1020 increases through the pathway blockage 1050 allowing more molding material 1020 to reach the gate 1092. If the molding material 1020 has a low viscosity or is relatively thin, a smaller drag force is imparted to the sensor 1010 and in turn a smaller displacement of the sensor 1010 is achieved so that the passage 1037 is decreased in size due to misalignment of the pathway blockage 1050 with the melt pathway 1030 (so as to increase blocking of the passage 1037). Once the passage 1037 is decreased in size, the flow rate of the molding material 1020 decreases through the melt pathway 1030 allowing less molding material 1020 to reach the gate 1092.
The actuator 1040 is coupled to the second side 1035 of pathway blockage 1050. The actuator 1040 is used to bias translational motion (toward the right side of
The description of the exemplary 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 concepts 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 exemplary embodiments, it will be apparent that modifications and enhancements are possible without departing from the concepts as described. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims:
