GB2622096A - A mould cavity with a flow distribution network - Google Patents

A mould cavity with a flow distribution network Download PDF

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Publication number
GB2622096A
GB2622096A GB2212837.5A GB202212837A GB2622096A GB 2622096 A GB2622096 A GB 2622096A GB 202212837 A GB202212837 A GB 202212837A GB 2622096 A GB2622096 A GB 2622096A
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GB
United Kingdom
Prior art keywords
mould
distribution network
mould cavity
flow distribution
flow
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
GB2212837.5A
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GB202212837D0 (en
Inventor
Mark Wright Jonathan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Enable Mfg Ltd
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Enable Mfg Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Enable Mfg Ltd filed Critical Enable Mfg Ltd
Priority to GB2212837.5A priority Critical patent/GB2622096A/en
Publication of GB202212837D0 publication Critical patent/GB202212837D0/en
Publication of GB2622096A publication Critical patent/GB2622096A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C39/026—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles characterised by the shape of the surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/22—Moulds for peculiarly-shaped castings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
    • B22D15/02—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor of cylinders, pistons, bearing shells or like thin-walled objects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/22—Component parts, details or accessories; Auxiliary operations
    • B29C39/26—Moulds or cores
    • B29C39/265—Moulds or cores comprising two large plates positioned at a small distance from each other, e.g. for making panels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/42—Moulds or cores; Details thereof or accessories therefor characterised by the shape of the moulding surface, e.g. ribs or grooves
    • B29C2033/422—Moulding surfaces provided with a shape to promote flow of material in the mould cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/22—Component parts, details or accessories; Auxiliary operations
    • B29C39/24—Feeding the material into the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/22—Component parts, details or accessories; Auxiliary operations
    • B29C39/26—Moulds or cores

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

A mould 1 defines a mould cavity 3 and a first flow distribution network 15; a cast article void 11 defined at least in part by a mould cavity wall surface and the first flow distribution network 15 are fluidly connected to each other. The first flow distribution network 15 comprises at least one first channel 17 that extends across at least a part of the mould cavity 3 that defines at least in part the cast article void 11. The at least one first channel may comprise an inlet artery which branches into two or more ducts. The mould is particularly for casting thin wall plates wherein the surface of the plate is provided with protrusions in the shape of the flow distribution network; the protrusions may increase structural stiffness, or may be removed after moulding by milling. A cast or moulded article 5, 201, 301 produced using the mould is also provided.

Description

A MOULD CAVITY WITH A FLOW DISTRIBUTION NETWORK
The present invention relates to a casting or moulding process that facilitates the production of thin-walled cast articles, for example from materials such as aluminium alloys and polymers.
The ability to cast or mould thin-walled sections of parts, i.e. sections in which the surface area of the section is substantially larger than the cross-sectional area of the section (for example a thin plate section) is limited because it is difficult to completely fill the mould with the casting or moulding material. Furthermore, it is difficult to ensure that as the casting or moulding material cools it solidifies without creating any defects in the cast or moulded article, such as voids or cold shuts. Whilst casting processes such as high pressure die casting and vacuum casting can be used to produce cast articles with thin-walled sections, these processes still impose limitations on the design of cast articles and they significantly increase the manufacturing costs of those cast articles. Consequently, there is scope for utilising new moulds and casting and moulding techniques for improving high pressure casting processes, so that, for example, they can create parts with sections having even thinner walls. Other casting processes such as investment casting and sand casting require sections to have substantially thicker walls. For example, a wall thickness below 4mm in a cast article made from an aluminium alloy in a sand casting process would be consider difficult to achieve.
There are two dominant factors that limit the ability to cast or mould thin-walled sections of cast or moulded articles. The first factor is that the flow resistance of a mould cavity is increased if it has a high surface area relative to its cross-sectional flow area, i.e. its cross-sectional area transverse to the direction in which the casting or moulding material flows through the mould cavity. This scenario is present in thin-walled sections. If the flow resistance is too high, then the mould cavity will not be completely filled with the casting or moulding material. This is commonly called a misrun. The second factor results from the cooling of the casting or moulding material within the mould. As the casting or moulding material cools, and starts to transition from a liquid state to a solid state, it contracts in size. This contraction is counteracted by 'feeding' the mould cavity with more casting or moulding material supplied from feeders that are fluidly connected to the mould cavity. However, in a scenario in which the mould cavity has a high surface area and a low cross-sectional flow area, i.e. it is a mould cavity to produce a thin-walled section in a cast or moulded article, the rate of cooling of the casting or moulding material is high and the flow resistance experienced by the casting or moulding material is high. Consequently, it is not possible to feed enough new casting or moulding material into the mould cavity from the feeders. This will result in a number of types of casting defects, such as porosity and tears. These two factors are dominant in sand and investment casting and are also present in all casting processes for all materials.
Consequently, there is a need for a new casting or moulding process that can produce thin-walled sections in cast or moulded articles at relatively low cost and without having to make compromises to the design features of the cast or moulded articles.
Accordingly, the present invention provides in a first aspect a mould defining a mould cavity, wherein a cast article void is provided within the mould cavity and the mould further comprises a first flow distribution network, wherein the cast article void and the first flow distribution network are fluidly connected to each other, wherein a surface of the wall of the mould cavity defines at least in part the cast article void and wherein the first flow distribution network comprises at least one first channel that extends across at least a part of the mould cavity that defines at least in part the cast article void.
The present invention provides a solution to enable the production of cast or moulded articles, in any casting or moulding process, that have thinner wall sections than can be achieved by the use of prior art processes. The present invention provides a surface topology to a mould cavity of a mould, and consequently to a cast or moulded article produced using that mould, that reduces the resistance to the flow of moulding or casting materials in sections of mould cavities that have high surface areas and low cross-sectional flow areas, for example sections of mould cavities that are for producing thin-walled sections of cast or moulded parts. The reduced resistance to the flow of casting or moulding material through the mould cavity facilitates the production of cast or moulded articles with nominally thinner walls that has previously been possible using prior art methods. The surface topology also presents a lower resistance to the flow of feed metal into the mould cavity from a feeder which encourages the flow of casting or moulding material from the feeder into the mould cavity, thereby helping to prevent the formation of casting or moulding defects. Furthermore, the surface topology provides a better thermal pathway through the mould than has been provided by prior art moulds and processes. The improved thermal pathway provides a flow of additional heat into the thin-walled sections, which results in a reduction in the rate at which the casting or moulding material cools within the mould, thus reducing the presence of casting defects associated with sub-optimal cooling rates. In addition, the surface topology can be designed to increase the structural stiffness and strength of a cast or moulded article in the regions local to the features of the surface topology.
Preferably, the at least one first channel of the first flow distribution network comprises an inlet artery which branches into two or more primary intermediate ducts.
In one alternative, the inlet artery has the same cross-sectional flow area as the combined cross-sectional flow area of the two or more primary intermediate ducts.
In another alternative, the inlet artery has a greater cross-sectional flow area than the combined cross-sectional flow area of the two or more primary intermediate ducts.
In one alternative, each of the two or more primary intermediate ducts branches into two or more secondary intermediate ducts and each primary intermediate duct has the same or greater cross-sectional flow area than the combined cross-sectional flow area of the two or more secondary intermediate ducts into which it has branched.
In another alternative, each of the two or more primary intermediate ducts branches into two or more secondary intermediate ducts and each primary intermediate duct has the same cross-sectional flow as the combined cross-sectional flow area of the two or more secondary intermediate ducts into which it has branched.
Preferably, the cast article void and the first flow distribution network are provided within the mould cavity.
Preferably, the at least one first channel extends across at least a part of a surface of the wall of the mould cavity that defines at least in part the cast article void.
Preferably, at least a part of the first flow distribution network is recessed into the surface of the wall of the mould cavity.
Preferably, at least a part of the surface of the first flow distribution network is provided with grooves which run outwardly in a direction away from the centre of the at least one first channel.
Preferably, at least a part of the surface of the at least one first channel is provided with grooves which run outwardly in a direction away from the centre of the at least one first 35 channel.
Preferably, the at least one first channel is provided with a surface that is not smooth and which is provided with a plurality of surface irregularities.
Preferably, the at least one first channel is provided on a first wall of the mould cavity, wherein at least one second channel is provided on a second wall of the mould cavity and extends across at least a part of a surface of that second wall, and wherein the first wall and the second wall define at least in part the cast article void.
The present invention provides in a second aspect a cast or moulded article produced using a mould according to the present invention.
The present invention will be described here with reference to the following figures: Figure 1 is a perspective view of a partial mould for producing a cast article according is to a first embodiment of the invention; Figure 2 is a perspective view of the partial mould of Figure 1; Figure 3 is a plan view of the partial mould of Figure 1; Figure 4 is a perspective view of a cast article produced using the partial mould of Figure 1; Figure 5 is a cross-sectional view of a flow distribution network of the partial mould of Figure 1; Figure 6 is a perspective view of a cast article according to a second embodiment of the present invention; Figure 7 is a perspective view of the lower part of a mould used to cast the cast article of Figure 6; and Figure 8 is a perspective view of a cast article according to a third embodiment of the present invention.
A mould 1 according to a first embodiment of the present invention is shown in Figure 1. The mould 1 shown in Figure 1 is a partial mould that is part of a larger mould structure (not shown) that has other features such as a pouring basin, down sprue, filter, runners, risers and feeders. The mould 1 has an upper mould part 2 and a lower mould part 4 which together form a mould cavity 3 with a shape that is complementary to the shape of a cast article 5 to be cast from the mould 1. The cast article 5 is shown in Figure 4. The mould cavity 3 has an inlet side 7 and an outlet side 9. The mould cavity 3 comprises a cast article void 11 with an inlet opening 12 on the inlet side 7 of the mould 1 and an outlet opening 14 on the outlet side 9 of the mould 1, a left-hand flow distribution channel network 13 and a right-hand flow distribution network 15. The left-hand and right-hand flow distribution networks are provided between the inlet side 7 and the outlet side 9 of the mould cavity 3. The left-hand and right-hand flow distribution channel networks 13,15 have the same features as each other and consequently the following description of the right-hand flow distribution channel network 15 applies equally to the left-hand flow distribution channel network 13.
The right-hand distribution channel network 15 comprises an upper channel region 17 that extends outwardly from an upper surface 19 of the cast article void 11 and a lower channel region 21 that extends outwardly from a lower surface 23 of the cast article void 11. The upper and lower channel regions 17,21 have the same features as each other. Consequently, the following description of the lower channel region 21 applies equally to the upper channel region 17.
The lower channel region 21 is illustrated in perspective in view Figure 2 and in plan view in Figure 3. It comprises an inlet artery 25 that branches into two primary intermediate ducts 27. The primary intermediate ducts 27 each branch into two secondary intermediate ducts 29, the secondary intermediate ducts 29 each branch into two tertiary intermediate ducts 31, the tertiary intermediate ducts 31 each branch into two quaternary intermediate ducts 33 and the quaternary intermediate ducts 33 each branch into two outlet capillaries 35. Therefore, the right hand flow distribution channel network 15 branches out from one inlet artery to thirty-two outlet capillaries 35.
The inlet artery 25 has the largest cross-sectional flow area and each outlet capillary 35 has the smallest cross-sectional flow area. The cross-sectional flow areas of the intermediate ducts step down in size between the primary intermediate duct 27, the secondary intermediate duct 29, the tertiary intermediate duct 31 and the quaternary intermediate duct 33. There is also a narrowing in the cross-sectional flow areas within each of the primary, secondary, tertiary and quaternary ducts 27,29,31,33 and the outlet capillaries 35 along their lengths, between their inlets and their outlets. The combined cross-sectional flow area of the two primary intermediate ducts 27 is less than the cross-sectional flow area of the inlet artery 25, The combined cross-sectional flow area of the two secondary intermediate ducts 29 is less than the combined cross-sectional flow area of the two primary intermediate ducts 27. The combined cross-sectional flow area of the two tertiary intermediate ducts 31 is less than the combined cross-sectional flow area of the two secondary intermediate ducts 29. The combined cross-sectional flow area of the two quaternary intermediate ducts 33 is less than the combined cross-sectional flow area of the two tertiary intermediate ducts 31 and the combined cross-sectional flow area of the two outlet capillaries 35 is less than the combined cross-sectional flow area of the two quaternary intermediate ducts 33.
The upper channel region 17 and the lower channel region 21 of the right-hand flow distribution network are vertically spaced from each other because they are located above and below the cast article void 11 which is sandwiched between them. The lines at which the upper and lower channel regions 17,21 interface with the cast article void 11 define, along with the inlet side 7 and outlet side 9 of the mould 1, lateral flow slots 36. The lateral flow slots 36 run along each side of the primary artery 25, the intermediate ducts 27,29,31,33 and the outlet capillaries 35.
Figure 4 is a perspective view of the cast article 5 that is produced from the mould 1. The principal form of the cast article 5 is that of a thin rectangular plate 37 that has a constant thickness t1. The upper surface 39 of the plate 37 is provided with a protrusion 41 in the shape of the left-hand flow distribution network 13 of the mould 1 and a protrusion 43 in the shape of the right-hand flow distribution network 15 of the mould 1. The lower surface 45 is provided with similar protrusions (not shown). The protrusions 41,43 form part of the cast article 5 and the protrusions 41,43 be retained as part of that cast article 5, or they can be removed, partially or wholly, in a subsequent operation, for example in a milling machine.
To cast a cast article 5 according to the first embodiment of the present invention the casting material, for example a molten aluminium alloy, is introduced into the mould 1 through an in-gate (not shown) and flows across the mould in one direction, as indicated by the flow direction arrow in Figure 1. The casting material flows initially into the mould cavity 3 through its inlet side 7, across the entire width of the inlet opening 12 of the cast article void 11, and through the inlet artery 25 of each of the left-hand flow distribution network 13 and the right-hand flow distribution network 15. The inlet artery 25 has a relatively large cross-sectional flow area compared to the surface area of its internal wall. Consequently, the inlet artery 25 has a lower resistance to the flow of the casting material than the resistance to flow of the casting material produced by the inlet opening 12, which, having the form of a narrow rectangular slot, has a relatively small cross-sectional flow area compared to the surface area of its internal wall.The relatively low resistance to flow of the inlet artery 25 causes the flow rate of casting material within the inlet artery 25 to be higher than the flow rate of casting material through the inlet opening 12 of the cast article void 11. As a result, more casting material is able to flow into the mould cavity 3 through the inlet arteries 25, than through the inlet opening 12. Therefore, the inlet arteries 25 are able to channel the casting material into the mould cavity 3 more quickly, which is advantageous because it reduces the time over which the casting material is able to cool and thereby increases the time for which the casting material remains in its liquid form.
A leading edge is provided at the front of the casting material that flows into the mould cavity 3. There is surface friction, or flow resistance, between that leading edge and the walls of the tip mould cavity 3 and that surface friction is lower within each primary artery 25 than it is in the cast article void 11, because the leading edge is in contact with a smaller surface in the primary artery 25 than it is in the cast article void 11. The lower surface friction within the primary artery 25 is another factor that contributes to the relatively high flow rate of the casting material within the primary artery 25.
As the casting material flows along the inlet artery 25 it also flows into the cast article void 11 through the portion of the lateral flow slots 36 that run along each side of the primary artery 25. The flow of casting material that flows through the lateral flow slots 36 joins up with the casting material that has entered the mould cavity 3 through the inlet opening 12.
The casting material flows along each inlet artery 25 until it reaches an interface where the inlet artery 25 branches into the two primary intermediate ducts 27. The combined cross-sectional flow area of the two primary intermediate ducts 27 is lower than the cross-sectional flow area of the inlet artery 25 and this creates back pressure within the inlet artery 25. This back pressure is utilised to increase the rate of flow of the casting material out of the lateral flow slots 36 on either side of the inlet artery 25.
As the casting material flows through each primary intermediate duct 27 it flows out into the cast article void 11 through the lateral flow slots 36, in the same manner as described above in relation to the primary inlet 25. The branching of each primary intermediate duct 27 into two secondary intermediate ducts 29, which have a lower combined cross-sectional flow area than the primary intermediate duct 27, creates a back pressure in each of primary intermediate duct 27, which has the effect of forcing the casting material through the lateral flow slots 36 into the cast article void 11, as previously described.
This effect takes place in each tertiary intermediate duct 31, each quaternary intermediate duct 33 and in each outlet capillary 35.
The pressure of the casting material reduces between the inlet side 7 and the outlet side 9 of the mould cavity 3. Consequently, the force driving the casting material out from each of the left-hand flow distribution network 13 and the right-hand flow distribution network 15 into the cast article void 11 reduces as they move away from the inlet side 7. This drop in pressure is compensated for by the branching of each of the primary inlets 25, the intermediate ducts 27,29,31,33 and the outlet capillaries 35 which, in steps, creates a greater distance of lateral flow slots 36 with increasing distance from the inlet side 7 of the mould cavity 3.
io Figures 1 to 5 illustrate a first embodiment of the present invention with a mould 1 with a mould cavity 3 for producing a cast arficle 5 that is a thin sheet with a constant thickness t1. Figure 6 illustrates a cast article 201 produced using a second embodiment of the process of the present invention that is a tapered plate 203 has a thickness that reduces from a thickness t2 at its left-hand end to a thickness of t3 at its right-hand end. The tapered plate 203 has an inlet side 202 and an outlet side 204. Five protrusions 205,207,209,211,213 are provided on the upper surface 215 of the tapered plate 203 and five protrusions 217,219,221,223,225 are provided on the lower surface 227 of the tapering plate 203. The protrusions 205,207, 209, 211, 213, 217, 219, 221, 223, 225 are produced by a flow distribution network 226 in the mould (not shown) for the cast article 201. The protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225 run across the tapered plate 203 in a direction perpendicular to the direction in which it tapers and are spaced from each other in the direction in which the tapered plate 203 tapers. The flow direction of the casting material through the mould when the cast article 201 was cast is shown by an arrow in Figure 6.
The protrusions 205,207, 209, 211, 213 on the upper surface 215 of the tapered plate 203 and the protrusions 217, 219, 221, 223, 225 on the lower surface 217 of the tapered plate 203 are vertically spaced from each other because they are located above and below the tapered plate 203 which is sandwiched between them.
The form of the protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225 can be adjusted at a macro level, a medial level and/or at a micro level, dependent upon the flow distribution that is required to form the cast article 201.
At a macro level, the height H, the width W, and therefore the internal volume of each of the protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225 can be adjusted. For example, the protrusions 205, 217 that are located towards the thick end of the tapered plate 203 have a width W1 and a height H1. The protrusions 213,225 that are located towards the thin end of the tapered plate 203 have a width W5 and a height H5. The other protrusions 207, 209, 211, 219, 221, 223 have varying widths and heights. The protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225 are generally triangular or semi-circular in cross-section, with the width W defining the width of the base of the triangular form and the height H defining the height of the apex of the triangular form, relative to the upper or lower surface 215,227 of the tapered plate 203.
At a medial level, ridges 229 are provided that run along the surface of the protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225. In some instances, the ridges 229 can also io extend from the protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223,225 across the upper and lower surfaces 215,227 of the tapered plate 203.
At a micro level, surface irregularities 231 are provided on the surfaces of the ridges 229 and on the surfaces of the protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223,.
The protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225 are shown in Figure 5 as having a generally linear, non-branching form. However, the protrusions 205, 207, 209, 211, 213, 217, 219, 221, 223, 225 of the second embodiment of the invention can have a branching form as described in relation to the first embodiment. Also, the first embodiment of the present invention can be provided with macro, medial and micro features as described in relation to the second embodiment.
Figure 7 shows a lower mould part 251 forming part of a mould cavity 252 used to cast the cast article 201. The mould part 251 comprises a flow distribution network 253 comprising lower channel regions 255, 257, 259, 261, 263, corresponding to protrusions 217, 219, 221, 223 and 225 of the cast article 201 respectively. An upper surface 265 of the lower mould part 251 forms a lower boundary of a cast article void 267 that corresponds to the tapered plate 203. The upper boundary of the cast article void 267 is formed by the lower surface of an upper mould part (not shown). The cast article void 267 has an inlet opening 269 and an outlet opening 271. The lines at which the lower channel regions 255, 257, 259, 261, 263 interface with the cast article void 267 define, along with an inlet side 202 and an outlet side 204 of the mould, lateral flow slots 273, which run along each side of the lower channel regions 255, 257, 259, 261, 263. Each lower channel region 255, 257, 259, 261, 263 is provided on its outer surface with grooves 275, which produce the ridges 229 of the cast article 201. The grooves 275 and the lower channel regions 255, 257, 259, 261, 263 are also provided with surface irregularities 277.
To cast a cast article 201 according to the second embodiment of the present invention the casting material, for example a molten aluminium alloy, is introduced into the mould cavity 252 of through an in-gate (not shown) and flows across the mould cavity 252 in one direction, from the inlet side 202 to the outlet side 204, as indicated by the flow direction arrow in Figure 7.
The casting material flows into the mould cavity 252 through the inlet opening 269 and through the lower channel regions 255, 257, 259, 261 and 263 of the flow distribution network 253.
The lower channel regions 255, 257, 259, 261 and 263 each have a relatively large cross-sectional flow area compared to the surface area of their internal wall. Consequently, casting material flowing within the lower channel regions 255, 257, 259, 261 and 263 is subjected to a lower resistance to the flow of the casting material than the resistance to flow of the casting material produced by the inlet opening 269, which, having the form of a narrow tapering slot, has a relatively small cross-sectional flow area compared to the surface area of its internal wall. The relatively low resistance to flow of the lower channel regions 255, 257, 259, 261 and 263 causes the flow rate of casting material within the lower channel regions 255, 257, 259, 261 and 263 to be higher than the flow rate of casting material through the inlet opening 269. As a result, more casting material is able to flow into the mould cavity 252 through the lower channel regions 255, 257, 259, 261 and 263 than through the inlet opening 269. Therefore, the lower channel regions 255, 257, 259, 261 and 263 are able to channel the casting material into the mould cavity 252 more quickly, which is advantageous because it reduces the time over which the casting material is able to cool and thereby increases the time for which the casting material remains in its liquid form.
A leading edge is provided at the front of the casting material that flows into the mould cavity 252. There is surface friction, or flow resistance, between that leading edge and the walls of the mould cavity 252 and that surface friction is lower within each lower channel region 255, 257, 259, 261 and 263 than it is in the cast article void 267, because the leading edge is in contact with a smaller surface in each of the lower channel regions 255, 257, 259, 261 and 263 than it is in the cast article void 267. The lower surface friction within each of the lower channel regions 255, 257, 259, 261 and 263 is another factor that contributes to the relatively high flow rate of the casting material within each of the lower channel regions 255, 257, 259, 261 and 263.
As the casting material flows along each of the lower channel regions 255, 257, 259, 261 and 263 it also flows into the cast article void 267 through the portion of the lateral flow slots 273 that run along each side of the lower channel regions 255, 257, 259, 261. The flow of casting material that flows through the lateral flow slots 273 joins up with the casting material that has entered the mould cavity 252 through the inlet opening 269.
The casting material flows out of the lower channel regions 255, 257, 259, 261 into the cast article void 267 and also flows into the cast article void 267 via the ridges 229. The surface irregularities 277 help to break the surface tension of the casting material, thereby reducing the resistance to flow within the flow distribution network 253. The surface irregularities 277 are provided in large numbers across the surface of the grooves 275 and the lower channel regions 255, 257, 259, 261, 263. Each of the surface irregularities creates a point at which the io surface tension in the casting material can be broken. Due to the large numbers of surface irregularities the surface tension of the casting material is continually broken as it flows along the grooves 275 and the lower channel regions 255, 257, 259, 261, 263. This assists with creating a flow of the casting material that is more uniform, for example because the continual breaking of the surface tension helps to avoid fluctuations in the speed of the flow.
Figure 8 illustrates a cast article 301 that is a thin-walled cube and is produced using a third embodiment of the process of the present invention. A protrusion network 303 comprising a plurality of protrusions (formed by a flow distribution network in an associated mould -not shown) flows over the surface of each of the six external faces of the cast article 301. The protrusions 303 flow across the top face 305 and down the four side faces. Two side faces 307, 309 are shown in Figure 8 and some of the protrusions that flow across them are described below.
A first protrusion 311 runs across the top face 305, over the top edge 313 of side face 307, then downwards across side face 307 at an angle such that it reaches the right hand side edge 315 of side face 307 and then across side face 309 until it joins up with the side of a second protrusion 317 on the side face 309. The second protrusion 317 continues along side face 309 until and then comes to an end 319 at a point near to the bottom edge 321 of the side face 309 by tapering down until it merges into the surface 323 of side face 309.
A third protrusion 325 also runs across the top face 305, over the top edge 313 of side face 307, then downwards across side face 307 at an angle such that it reaches the right hand side edge 315 of side face 307 and then across side face 309. At about half way down the side face 307 the third protrusion branches out into a left-hand protrusion branch 327 and a right-hand protrusion branch 329. The left-hand and right-hand protrusion branches 327,329 each have a cross-sectional area that is less than the cross-sectional area of the third protrusion 325. The left-hand and right-hand protrusion branches 327,329 continue running down the side face 307 until they end at the bottom edge 331 of the side face 309.
The form of protrusions such as the first, second and third protrusions 311, 317, 325 and the form of the protrusion branches such as the left-hand and right-hand protrusion branches 327, 329 can be adjusted at a macro level, a medial level and/or at a micro level, dependent upon the flow distribution that is required to form the cast article 301.
At a macro level, the height H, the width W, and therefore the internal volume of each of the to protrusions 311, 317, 325 and the protrusion branches 327, 329 can be adjusted.
At a medial level, ridges 333 are provided that run along the surface of the protrusions 311, 317, 325 and the protrusion branches 327, 329. In some instances, the ridges 333 can also extend from protrusions 311, 317, 325 and the protrusion branches 327, 329 across the surfaces of the faces 305, 307, 309 of the cast article 301.
At a micro level, surface irregularities 335 are provided on the surfaces of the ridges 333 and protrusions 311, 317, 325 and the protrusion branches 327, 329.
To cast a cast article 301 according to the third embodiment of the present invention the casting material, for example a molten aluminium alloy, is introduced into a mould cavity of a mould through an in-gate (not shown). The flow is generally downwards from an inlet side to an outlet side, as shown in Figure 8, but also flows laterally, for example across the top face 305. The casting material flows into the mould cavity through one or more inlet openings and through a flow distribution network that creates the protrusion network 303.
The casting process for the third embodiment works in a similar way to that of the first and second embodiments. The channels of the flow distribution network have a relatively large cross-sectional flow area compared to the surface area of their internal wall. Consequently, casting material flowing within the flow distribution network is subjected to a lower resistance to the flow of the casting material than the resistance to flow of the casting material produced by the inlet openings of the thin-walled sides of the cube (in the areas not covered by the flow distribution network), which, having the form of a narrow slots have a relatively small cross-sectional flow area compared to the surface area of their internal walls. The relatively low resistance to flow of the flow distribution network causes the flow rate of casting material within the flow distribution network to be higher than the flow rate of casting material through the inlet openings. As a result, more casting material is able to flow into the mould cavity through the flow distribution networks than through the inlet openings. Therefore, the flow distribution network is able to channel the casting material into the mould cavity more quickly, which is advantageous because it reduces the time over which the casting material is able to cool and thereby increases the time for which the casting material remains in its liquid form.
A leading edge is provided at the front of the casting material that flows into the mould cavity. There is surface friction between that casting material and the walls of the mould cavity and that surface friction is relatively lower within the flow distribution network, because relatively less mould material is in contact with a smaller surface. The lower surface friction within the to flow distribution network is another factor that contributes to the relatively high flow rate of the casting material within the flow distribution network.
The surface irregularities 335 help to break the surface tension of the casting material, thereby reducing the resistance to flow within the flow distribution network.
The surface topology of the present invention is designed so that its form provides optimised flow paths along which the casting or moulding material flows through the mould. The mould cavity can then be filled with the casting or moulding material in a way that creates both a defect free cast or moulded article and in a way that enables the amount of the casting or moulding material that needs to be supplied to the mould to be reduced to a minimum amount.
Consequently, the geometry of the cast or moulded article is the factor which has the largest influence on the design of the surface topology. Importantly, the present invention also allows for other factors to be taken into account when designing the surface topology. Those other factors include the material characteristics of the casting or moulding material, the material characteristics of the material from which the mould is made and any other process parameters of the casting or moulding process as a whole. Figures 1 to 4 illustrate a surface topology provided with ducts which branch out into smaller ducts with smaller cross-sectional flow areas. Figures 6 and 7 illustrate a surface topology with generally parallel ducts of different cross-sectional flow areas that are also provided with ridges and surface irregularities.
Figure 8 illustrates a surface topology which has branching ducts and parallel ducts. Many other surface topologies are envisaged because they will be needed to provide optimised flow paths for all of the many different types of cast or moulded articles that can be produced by the process of the present invention.

Claims (14)

  1. CLAIMSA mould (1) defining a mould cavity (3), wherein a cast article void (11) is provided within the mould cavity (3) and the mould (1) further comprises a first flow distribution network (15), wherein the cast article void (11) and the first flow distribution network (15) are fluidly connected to each other, wherein a surface of the wall of the mould cavity (3) defines at least in part the cast article void (11) and wherein the first flow distribution network (15) comprises at least one first channel (17) that extends across at least a part of the mould cavity (3) that defines at least in part the cast article void (11).
  2. A mould (1) as claimed in claim 1, wherein the at least one first channel of the first flow distribution network comprises an inlet artery (25) which branches into two or more primary intermediate ducts (27).
  3. 3. A mould (1) as claimed in claim 2, wherein the inlet artery (25) has the same cross-sectional flow area as the combined cross-sectional flow area of the two or more primary intermediate ducts (27).
  4. 4. A mould (1) as claimed in claim 2, wherein the inlet artery (25) has a greater cross-sectional flow area than the combined cross-sectional flow area of the two or more primary intermediate ducts (27).
  5. 5. A mould (1) as claimed in any one of claims 2, 3 or 4, wherein each of the two or more primary intermediate ducts (27) branches into two or more secondary intermediate ducts (29) and each primary intermediate duct (27) has a greater cross-sectional flow area than the combined cross-sectional flow area of the two or more secondary intermediate ducts (29) into which it has branched.
  6. 6. A mould (1) as claimed in any one of claims 2, 3 or 4, wherein each of the two or more primary intermediate ducts (27) branches into two or more secondary intermediate ducts (29) and each primary intermediate duct (27) has the same cross-sectional flow as the combined cross-sectional flow area of the two or more secondary intermediate ducts (29) into which it has branched.
  7. 7. A mould (1) as claimed in any one of the preceding claims, wherein the cast article void (11) and the first flow distribution network (15) are provided within the mould cavity (3). 8. 9. to 13
  8. A mould (1) as claimed in claim 5, wherein the at least one first channel (17) extends across at least a part of a surface of the wall of the mould cavity (3) that defines at least in part the cast article void (11).
  9. A mould (1) as claimed in claim 6, wherein at least a part of the first flow distribution network (15) is recessed into the surface of the wall of the mould cavity (3).
  10. A mould (1) as claimed in any one of the preceding claims, wherein at least a part of the surface of the first flow distribution network (15) is provided with grooves which run outwardly in a direction away from the centre of the at least one first channel (17).
  11. A mould (1) as claimed in claim 10, wherein at least a part of the surface of the at least one first channel (17) is provided with grooves which run outwardly in a direction away from the centre of the at least one first channel (17).
  12. A mould (1) as claimed in any one of the preceding claims wherein the at least one first channel (17) is provided with a surface that is not smooth and which is provided with a plurality of surface irregularities.
  13. A mould (1) as claimed in any one of the preceding claims, wherein the at least one first channel (17) is provided on a first wall of the mould cavity (3), wherein at least one second channel (21) is provided on a second wall of the mould cavity (3) and extends across at least a part of a surface of that second wall, and wherein the first wall and the second wall define at least in part the cast article void (11).
  14. 14. A cast or moulded article (5, 201, 301) produced using a mould as claimed in any one of claims 1 to 13.
GB2212837.5A 2022-09-02 2022-09-02 A mould cavity with a flow distribution network Pending GB2622096A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2212837.5A GB2622096A (en) 2022-09-02 2022-09-02 A mould cavity with a flow distribution network

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Application Number Priority Date Filing Date Title
GB2212837.5A GB2622096A (en) 2022-09-02 2022-09-02 A mould cavity with a flow distribution network

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GB202212837D0 GB202212837D0 (en) 2022-10-19
GB2622096A true GB2622096A (en) 2024-03-06

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0106203A1 (en) * 1982-09-21 1984-04-25 Georg Fischer Aktiengesellschaft Cast thin-walled body
JPS6179637A (en) * 1984-09-28 1986-04-23 Seikosha Co Ltd Manufacture of pointer
JPH03128164A (en) * 1989-10-11 1991-05-31 Mitsui Eng & Shipbuild Co Ltd Production of ti or ti alloy casting
US5529645A (en) * 1994-05-17 1996-06-25 Northrop Grumman Corporation Thin wall casting and process
JP2004058099A (en) * 2002-07-29 2004-02-26 Asahi Tec Corp Metallic mold for casting
WO2016146293A1 (en) * 2015-03-18 2016-09-22 Bayerische Motoren Werke Aktiengesellschaft Automotive body
DE102016103029A1 (en) * 2016-02-22 2017-08-24 Getrag Getriebe- Und Zahnradfabrik Hermann Hagenmeyer Gmbh & Cie Kg Housing for a vehicle powertrain and method of making the same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0106203A1 (en) * 1982-09-21 1984-04-25 Georg Fischer Aktiengesellschaft Cast thin-walled body
JPS6179637A (en) * 1984-09-28 1986-04-23 Seikosha Co Ltd Manufacture of pointer
JPH03128164A (en) * 1989-10-11 1991-05-31 Mitsui Eng & Shipbuild Co Ltd Production of ti or ti alloy casting
US5529645A (en) * 1994-05-17 1996-06-25 Northrop Grumman Corporation Thin wall casting and process
JP2004058099A (en) * 2002-07-29 2004-02-26 Asahi Tec Corp Metallic mold for casting
WO2016146293A1 (en) * 2015-03-18 2016-09-22 Bayerische Motoren Werke Aktiengesellschaft Automotive body
DE102016103029A1 (en) * 2016-02-22 2017-08-24 Getrag Getriebe- Und Zahnradfabrik Hermann Hagenmeyer Gmbh & Cie Kg Housing for a vehicle powertrain and method of making the same

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