MULTI-INPUT, MULTI-OUTPUT MANIFOLD FOR THERMOCONTROLLED SURFACES
20230182361 · 2023-06-15
Assignee
Inventors
Cpc classification
B29C2045/7343
PERFORMING OPERATIONS; TRANSPORTING
B29C45/7312
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A forming tool with forced thermal fluid-based spatio-temporal temperature control of a surface of the tool has a subsurface manifold underlying at least a part of a forming surface of the tool and a number P of at least 6 ports, each port fluid coupled respectively to the manifold via respective channels, where the ports exit the tool at disparate points, with each pair of ports in fluid communication via the manifold. This structure allows manifold path diversity for varying thermal fluid supply and drainage. The manifold may be reinforced.
Claims
1. A forming tool with thermal fluid-based spatio-temporal temperature control, the tool comprising: a subsurface manifold underlying at least a part of a thermocontrolled surface of the tool, the manifold bounded between a face-adjacent wall and a back-adjacent wall of the tool, and at least substantially surrounded by a peripheral wall; and a number P of at least 6 ports, each port fluid coupled respectively to the manifold via respective channels, the ports at disparate points, with each pair of ports in fluid communication via the manifold.
2. The forming tool according to claim 1 wherein ports occupy at most 70% of the back-adjacent wall.
3. The forming tool according to claim 1 wherein each of one or more channels extend through: the peripheral wall; or the back-adjacent wall.
4. The forming tool according to claim 1 wherein there are at least 8, 9, 10, 12, 15, 20, or 50 ports.
5. The forming tool according to claim 1 wherein the ports are regularly arrayed with uniform spacing on the back-adjacent wall.
6. The forming tool according to claim 1 wherein the manifold is reinforced with an open supporting structure that permits fluid circulation.
7. The forming tool according to claim 6 wherein the open supporting structure comprises a number of members arrayed across the manifold, the members configured as pillars, I-beams, spacers, or Kagome-shaped structures.
8. The forming tool according to claim 7 wherein each of the members are: joined to a common sheet, or to one or more strips; or adhered to the face- or back-adjacent wall by welding, adhesive, mechanical fastener, or by additive manufacturing.
9. The forming tool according to claim 1 wherein the tool comprises a mold of one of the following types: injection mold, powder injection mold, metal injection mold, casting mold, or a stamping die.
10. The forming tool according to claim 1 further comprising: at least one thermal fluid supply; a drain; and a respective flow control element mounted to each one of the P ports, to couple the respective port to at least one conduit, be it one of the at least one thermal fluid supply, or the drain, with: at least a minimum number M of the ports coupled via respective control elements to the drain, and at least M of the ports coupled via respective control elements to the first supply, where M=2+floor (15(P−6)/4P); where each flow control element is adapted to switch between at least two of the following states for a first of the at least one conduit to which it is coupled: a closed state where flow through the port is closed; a first open state where flow between the port and the first conduit has a first hydrodynamic resistance; and a second open state where flow between the port and first conduit has a second hydrodynamic resistance different by at least 10% than the first hydrodynamic resistance.
11. The forming tool according to claim 10 wherein: a set of the ports that selectively couple the manifold to the drain in dependence on a state of the flow control element defines a drain set, just as a set of ports selectively coupling to a first of the at least one thermal fluid supply defines a first supply set; both the drain set and the first supply set are substantially dispersed in that for each port in the first supply set: at least 2 of the 5 nearest ports are in the drain set; a mean distance to the 3 nearest ports of the first supply set is 15% greater than a mean distance to the 3 nearest ports of the drain set; or among the 5 nearest ports, a mean distance to the ports of the drain set is 15% less than the mean separation to the ports of the first supply set; and the drain set and first supply set: are disjoint subsets of the set of all ports; partition the set of all ports; have a non-trivial set intersection; or are mutually inclusive.
12. The forming tool according to claim 10 wherein at least one of the flow control elements couple the port to both the drain and the first thermal fluid supply, and is adapted to switch between open states of exclusively one of the drain and first thermal fluid supply.
13. The forming tool according to claim 10 wherein each flow control element is adapted to switch to the closed state.
14. The forming tool according to claim 1 further comprising: at least one thermal fluid supply; a drain; and a respective flow control element mounted at at least two of the ports, adapted to switch between these three states: a first state that couples a first thermal fluid supply to the manifold; a second state that couples the manifold to a drain: and a third state wherein the port is closed.
15. The forming tool according to claim 10 wherein at least two of the flow control elements further selectively couples a second thermal fluid supply to the manifold alternatively to coupling to the first thermal fluid supply, and to coupling to the drain.
16. The forming tool according to claim 10 wherein at least one of the flow control elements has a number of states for opening to drain or supply, each state corresponding to a respective opening hydrodynamic diameter.
17. The forming tool according to claim 10 wherein each flow control element is a mechanical valve or switch electronically controlled by a common processor.
18. The forming tool according to claim 10 further comprising: a thermal treatment centre adapted to receive fluid from the drain, change a temperature thereof, and pump the product to the first thermal fluid supply; or a common processor for controlling each of the flow control elements.
19. The forming tool according to claim 14 wherein the manifold is: closed, constraining the fluid to exit only via one of the ports; or is coupled by one or more channels to one or more other manifolds, and the manifold, channels and one or more other manifolds are collectively closed.
20. A kit for transforming a forming apparatus with thermal control channels into a multi-input, multi-output temperature controlled forming surface, the kit comprising at least 6 electromechanical flow controllers each flow controller adapted to couple the manifold to at least one of a first thermal fluid supply and a drain, for switching between at least two of the following states: a closed state where flow through the port is obstructed; a first open to source state where a first supplied thermal fluid may enter through the port at a first rate from the first thermal fluid supply; a second open to source state where a first supplied thermal fluid may enter through the port from the first thermal fluid supply at a second rate other than the first rate; a first open to drain state where thermal fluid may exit the manifold through the port at a third rate through the drain; and a second open to drain state where thermal fluid may exit the manifold through the port at a fourth rate other than the third rate.
21. The kit according to claim 20 further comprising a micromachining device adapted to be used alone or with other bits or materials, for at least partial insertion into a thermal control channel of the forming apparatus to join two or more separated thermal control channels to form a single manifold interconnecting at least 6 ports, the insertion provided by entry via existing ports of the separated channels of the forming apparatus, or by boring one or more new ports.
22. A method for controlling a spatio-temporal thermal distribution on a mold face of a forming apparatus, the method comprising: providing a forming tool according to claim 10 with respective flow control elements coupled to respective conduits; and applying a signal to control each of the flow control elements while thermal fluid supplies and drain are operating, to control a temperature at the mold face.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] In order that the invention may be more clearly understood, embodiments thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which:
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DESCRIPTION OF PREFERRED EMBODIMENTS
[0050] Herein a forming tool, and kit for transforming a forming tool with thermal control channels into a forming tool with a multi-input, multi-output temperature controlled forming surface is described, as well as a method for controlling a thermal distribution of a forming tool or apparatus, such as a mold.
[0051]
[0052] The specific shape shown is not designed to resemble any known part, and any similarity is unintentional, however the mold half can have substantial depth and variability in depth and can have abrupt edges and easier and more difficult regions for demolding. As shown, the mold face has a flat-bottomed cup area 12a joined by neck 12b to a base 12c having intrusions 13 that (as seen in
[0053] Surrounding the mold face, shown in ghost line, is a thermally controlled area 15 of the mold half 10. While the thermally controlled area encompasses the whole mold face in this embodiment, it need not cover the whole mold face as some parts of a mold face may be in greater need of enhanced temperature control, and not others. Furthermore, as shown, it is usual for thermal control to extend beyond the limits of the mold feature areas.
[0054] As seen in
[0055] As is well known in the art of conformal thermal control of molds, there is a trade-off between the closest approach between the channels and floor of mold (the nominal minimal thickness of the mold face above the manifold), as too thin a separation results in inferior strength of the mold, and too thick a separation reduces efficiency of the cooling. This trade-off is exacerbated by the enlargement and increased interconnection of channels to form the single connected manifold 20, and peaks with the unstructured, whole of area open plenum shown. Furthermore, the tradeoff becomes acute as the closer the thermal fluid gets to the formed material, the more effective the thermal control becomes. However, the fluid-based thermal control is of no use if the mold fails prematurely or the mold face deforms under thermal or mechanical loading during forming processes. As will be appreciated by those of skill in the art, mold halves are typically composed of particular materials chosen for longevity of the mold, costs, and stiffness used for forming molds for different processes and materials, and while the inclusion of a manifold may provide an impetus to use higher stiffness materials, to increase a plenum volume, it is expected to more often be cost efficient to reinforce the manifold with a scaffold, bridging structure, packing of high stiffness balls or cylinders, strip of joined supports or Kagome structures, space frame truss, or any sufficiently open (low hydrodynamic resistance) support structure.
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[0058] Each flow control element 30 may be a simple open/close valve, or may have a plurality of degrees of open states, each state corresponding with a respective pressure loss in flow across the valve (for example by varying hydrodynamic resistance), and further some of the flow control elements 30 may be of either kind. Once the hydrodynamic resistance is less than that of the fluid through the conduits 26/28, the flow control element is fully open (no further opening has any effect on flow rate). A small number, less than 20, more preferably less than 10, and most preferably 3-8 states of respective hydrodynamic resistance may be identified with distinct, open states of these flow control elements. The number of states of each valve greatly affects a number of thermal distributions applicable to the thermal control region by the system as a whole, at the expense of slightly more cumbersome control and costs of the system.
[0059] Each flow control element 30 shown couples two tube sections of the conduit to which it couples: i.e. either the supply 26 or the drain 28. This allows for a single serial conduit to sequentially feed each port 25, in dependence upon state of the flow control element. As such, each flow control element 30 illustrated has two tube coupling ends in communication with a first internal channel of the flow control element 30, a second internal channel coupled to the channel 22, and a sealed mechanical device for selectively interconnecting the two internal channels. Some flow control elements known in the art have only one opening to each internal channel, and it is trivial to provide T-couplers in the conduit 26,28 for each flow control element to provide an equivalent network.
[0060] The supply 26, as shown (just like the drain 28), happens to have 2 ends. Both ends of the supply 26 will come from a pump section of thermally treated fluid. While most often these fluids are high thermal transfer rate liquids, that are inert and have stable reliable rheology across the temperature range, they can also be gasses. Preferably the thermal fluid and manifold (with any reinforcement) and pump rates are selected to ensure that a flow regime through the manifold has a Reynolds number 1 to 1000 to avoid full turbulence. The two ends are not necessary as the second end can alternatively be a termination: the fluid can be fed from only one end. The first internal channels of all of the connected flow control elements 30 of the same conduit are in open fluid communication, regardless of the states of the other connected flow control elements. Thus the sealed mechanical devices are in parallel with the conduit 26,28. Likewise there could be any number of ends desired. In general, the more ends, the shorter the path between the supply/drain and the open flow control elements 30, which is advantageous for reducing thermal loss (particularly important for the supply 26), and fastest response time. The use of two ends is convenient as every flow control element 30 has a same number of couplers, and there is one redundant path to every port 25: if one tube section were to be blocked or constricted between two ports 25, the flow to no ports would be appreciably impaired, and there is very little penalty in tubing connections or complexity introduced by this redundancy. This is because flow through conduit 26,28 is not inherently directed flow (it can flow in either direction). Once one or several of the ports are open, unless there is some constriction, flow is balanced between both ends to meet the flow requirements.
[0061] As shown, the ports selectively coupled to drain (herein “drain-coupled”) and those coupled to supply (“supply-coupled”) partition the set of ports, and are equi-numerous. The drain-coupled set is reasonably uniformly distributed amongst the supply-coupled set and vice versa. In the illustrated embodiment, the nearest neighboring port of each port happens to not be a member of the same partition, although this is a stronger requirement than necessary. It would be expected that for each port: at most 3 of the 5 nearest ports are members of the same partition; a mean separation between the 5 nearest ports of the same partition is 15% greater than a mean separation between the 5 nearest ports of the opposite partition; or among the 5 nearest ports, a mean separation to the ports of the opposite partition is 15% less than the mean separation to the ports of the same partition. Such a distribution is preferred to facilitate a broadest range of thermal fluid distribution patterns, as will allow the system to apply varied response. However, it will be appreciated that a forming tool may have a larger number of ports than are usable, and an engineered solution to address a particular problem may be called for that does not require uniform distributions of drain- and supply-coupled sets. If a reconnection of ports to source and drain conduits is required, the system is as reconfigurable as the availability of ports.
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[0065] Finally,
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[0067] That said, direct thermal contact between the supply tubing 26 and drain 28 is a short-circuit thermal bridge that extends over a large surface area with this embodiment. Thus while the network connections of the 2-way valve system shown in
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[0070] In
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[0072] Applicant further notes that an embodiment intermediate those of
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[0075] The flow control circuit, or bus 32 is preferably coupled to a sensor 47, which is shown extending toward the manifold 20. The sensor 47 may be a flow rate sensor, such as a mass, velocity, or volume flow sensor, and/or a thermocouple or a resistance-based thermometer (for fast temperature change detection). Direct thermal measurement can be particularly advantageous if read by the flow control circuit, as this allows the local control over locally sensed parameters, as well as those of some neighbouring flow control circuits, can provide a robust processing architecture that can handle multiple faults and exceptions, although any variety of processing architectures are equally practicable. For example, if sampling of the sensors and instructions to respective flow control circuits can be time divided via the bus, all the thermal control can be provided by a single processor, conveniently located at the thermal processing system, which can also control pump rates and communicate with, comprise, or be comprised by, a process controller.
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[0078] The 4-way 4 position switches 30 are shown only with switching capability, but a variable flow resistance is coupled to the switch 30 at each port P, to further allow the controller 55 to throttle the flow through each port independently.
[0079] Control exerted by the controller may be assisted by the usual PID control algorithms, or by artificial intelligence driven by inputs and output response, where the inputs are control states of the flow control elements, temperature and pump rates of the thermal treatment system, and state of process in a process model, and the outputs may be quality of parts, demolding issues, or particular flaws.
EXAMPLES
[0080] To demonstrate the present invention, simulation results were produced with a multi-physics finite element simulator that modelled transient thermodynamics and fluid dynamics of a simple 25 port thermal control manifold having a regular array of ports to a square manifold. The dimensions were 250×250 mm, virtually filled with a fluid with physical properties (density, viscosity, specific heat and conductivity) of water. The boundary conditions set for the manifold were isothermal. In the examples the manifold was initially set at a maximum and uniform temperature, and the image shows flow rates after 6 s. The thermal fluid supplied was a low temperature fluid source. The simulated switch operation was Boolean, each port fully opened or closed states were predefined. Injected fluid effectively cooled down specific region according to the selected configuration.
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[0084] The described invention has been shown with the forming tool bearing a manifold with multiple input ports and multiple output ports. It will be appreciated by those of skill in the art that a wide variety of molds and other forming apparata can benefit from the present invention: including extremely high temperature, high pressure molds, such as those used in powder metallurgy; high temperature low pressure molds such as semisolid injection molding; to moderately high temperature low or higher pressure plastic injection molding apparata. Forming processes with a cycle time of seconds to hours or longer can all benefit, but particularly forming processes with cycle times on the order of one minute are particularly advantageous for temporal response of feedback that allows for a change in the thermal fluid distribution within a single cycle.
[0085] Other advantages that are inherent to the structure are obvious to one skilled in the art. The embodiments are described herein illustratively and are not meant to limit the scope of the invention as claimed. Variations of the foregoing embodiments will be evident to a person of ordinary skill and are intended by the inventor to be encompassed by the following claims.