GB2358368A - Manufacture of manifold modules or the like - Google Patents

Abstract

A method of manufacturing a component such as a pneumatic manifold module 58, incorporating integral passageways or chambers, comprises forming, for example by a rapid prototyping technique, a structure 50, in a first solid material, which has at least a portion which corresponds in configuration with the desired configuration of passages or chambers in the component, supporting the structure 50 in a mould 52, then filling the mould 52, in a vacuum chamber, with a curable liquid synthetic resin to encompass structure 50. The resin is caused or allowed to set and thereafter the resulting combination is washed in a solvent in which the first material is soluble but to which the cured resin is impervious, to remove the first material, leaving the desired passageways and/or chambers in the cured resin component.

Description

2358368 PATENTS ACT 1977 Agents' Reference: P13745GB-HWC/ac

DESCRIPTION OF INVENTION

Title: "Manufacture of manifold modules or the like" This invention relates to the manufacture of components incorporating internal passageways for fluids, e.g. for liquids or gases in hydraulic or pneumatic systems, for example. However, the method of the invention is also applicable to other applications in which it is necessary to form internal passages or chambers in certain structures.

In the manufacture of pneumatic and hydraulic systems, it is often convenient to connect valves, actuators, fluid motors etc. by way of solid blocks or manifolds, rather than by individual pipes connecting such components. Such a manifold typically provides a plurality of ports, with associated mountings, for connection with the valves, conduits, etc., the manifold having internal passageways connecting such ports. In some cases, a single manifold may incorporate a relatively complex network of such internal passageways, so that the block or manifold becomes analogous to a printed circuit board in electronics manufacture, with the various hydraulic or pneumatic components connected to such manifolds being analogous to the electronic components which might be mounted on such a printed circuit board. The solid block or manifold may itself incorporate other components, apart from simple fluid connections, of the hydraulic or pneumatic system of which it is to form part. For example, the block or manifold may incorporate flow restrictors or may incorporate chambers of larger volume than the passages which merely serve as connections between components, and which chambers act as delay elements in 2 pneumatic systems (e.g. in a manner analogous to capacitors in eleqdon c circuits as it takes time to raise and lower the gas pressure in a chamber).

It is frequently convenient to provide parts of pneumatic or hydraulic sql qm or in some cases to provide such systems in modular form, with such a nc du e comprising a manifold block together with the pneumatic or hy4r, iul. c components mounted thereon, such a module being thus analogous to a te d circuit board carrying various electronic components, in eleclrfoids manufacture.

In the past such a manifold has typically been produced by providing a ta 1, 1, eg. aluminium, or plastics, e.g. Perspex, block with a flat face and ma0h] 111 grooves or channels across the flat face in the configuration coffespon4it 1; to the desired configuration of internal passages or chambers in the ma#,M)ld. Where ports for connection of external piping or components are to be prON id in the block, these may be formed at the same time. Nowadays, machii#r 1; ( f such blocks is generally carried out by CNC (computer numerically cont: o I le automatic machines. After the block has been machined, a flat cover 011a e secured to the block over the channelled flat surface with the interpositi of a sealing gasket between the block and the cover plate, the cover plateJAe-ing secured to the metal block by bolts or screws engaging in screw-threadedl t ores also machined in the block. Ports for connecting the internal passages to ves and the like or to conduits or other devices may also be formed throuOl. tf, e cover plate, such ports having appropriate mounting means, such as $devthreaded connectors, etc., whereby such external conduits or devices r0a t e secured to the manifold. However it is normally preferable to confino uc h ports and mountings to the block itself 3 Another technique conventionally employed, particularly to form more complex, or "3 -dimensionaP arrangements of interconnecting chambers and passsageways, involves drilling variously oriented and variously intersecting bores of various diameters in a solid block, portions of bore which are not required for fluid communication in the finished product being plugged. One feature of this cross-drilling technique is that junctions between passages or sections of passages which intersect are necessarily effected at more or less abrupt angles or corners, whereas considerations of fluid flow would ideally dictate gradual curves or bends in many cases.

Such traditional manufacturing methods are fairly labour intensive and involve many machining steps and are thus expensive. The use of metal, such as aluminium, also adds to costs in the traditional manufacturing methods.

A variant of the traditional manufacturing process described above dispenses with the need for bolts or screws to secure the cover plate to the metal block and dispenses also with the need for a gasket. In this variant, the cover plate is bonded to the block by an appropriate adhesive or bonding agent which also serves to effect a seal between the cover plate and the block, or the cover plate is solvent bonded to the block. This technique has the advantage that the cover plate and the block require no machining to provide plain and threaded bores to receive screws or bolts, but machining steps are still required to form the channels or grooves m the block. Furthermore, the parts must be cleaned thoroughly before the bonding process and the faces to be glued together must be appropriately prepared. Additionally, there is a risk that bonding agent expressed from between the cover plate and the block when the two components are brought together will partially or completely block some of the channels defined between the cover plate and the block. The assembly process can also be rather messy. Furthermore, the integrity of the adhesive bond 4 between the cover plate and the block is difficult to assess, and the metc less reliable, than securing the cover plate by conventional bolts or s0dws. Furthermore, the bonding agent may take quite a significant time, e.g. 24 tc 4rs, to cure fully, and apart from the manufacturing delay involved, this maes it difficult to monitor usefully the success rate for securing the cover plat by this means. In a practical manufacturing scenario it will be logical to coijy ete other manufacturing steps during this curing time period, such as mountiol, the block the various pneumatic or hydraulic components required to cot'! let,the respective module. Unfortunately, if it proves that the cover plate hgo 01, after all, adhered properly to the block, these additional steps mean that t4o mst of the resulting scrap unit is increased and thereby overall manufacturin sti are increased. In addition, particularly where the cover plate is box Oed adhesively to the block, the fact that the product comprises two se,, rat. components means that large temperature changes can cause uneven ro,, liv movement between the block and cover plate, which can lead to failure',61'th seal between the block and cover plate in practice.

In addition, the conventional techniques described above are expensivf' an slow when used to produce a prototype, or other product in which onl iY One item, or a very few items, to a particular design is required.

It is an object of the invention to provide a method of manufacturing a rn,,O 61 I for a hydraulic or pneumatic system, which overcomes the aboveIn'tel disadvantages of the known techniques.

According to the invention there is provided a method of manufac Ig a manifold or fluid connection block comprising forming a structure, inl I in t solid material which corresponds in configuration to the desired config, qio a of passages and/or chambers in the manifold, supporting said structure d n a mould, then filling the mould with a second material in liquid or flowable condition, to encompass at least a desired portion of said structure, causing or allowing said second material to solidify to form the manifold block, and subsequently removing said first material to leave the desired passageways and/or chambers in the block.

The manufacture of a manifold in accordance with the invention is described below, by way of example, with reference to the accompanying drawings, in which:

Figure I is a schematic, "phantom" perspective view showing schematically a conventional manifold block or module block, which may be formed by crossdrilling as described above, Figure 2 is a schematic plan view, illustrating a temporary structure, defining the form of passages and/or chambers desired in a module or manifold block to be formed, located in a casting frame or open topped box, prior to the pouring of liquid resin to form such manifold block about the temporary structure, Figure 3 is a schematic view partly in vertical section, of the assembly illustrated in Figure 1, and Figures 4, 5 and 6 are schematic views, in vertical section, illustrating successive further stages in the manufacture of a manifold or fluid connection module block in accordance with the invention.

The preferred method embodying the invention is described in more detail below with reference to the drawing.

6 The design of a module block in accordance with the invention may be 01 out in conventional manner. When the design stage has been compI lt a temporary structure, in a soluble or otherwise readily removable mat 1 is produced in any convenient way. Thus, using contemporary stereolith+ ipt y orm. and configuration of the pcls#g(s or rapid prototyping" techniques, the f and chambers in the module block may be designed, in manner known Pe se, using CAD (computer aided design). The design procedure may invo,Y( tb e creation of a stereolithography file embodying a 3D image of the tenT(Iary structure and the use of a 31) printer and stereolithography to proditi,c tfle temporary structure in a solid material readily soluble in a convenient so 1, 'n (or a material otherwise readily ablated, for example by heat) and hic 1 temporary structure has the size, shape and configuration of the spacs and passages desired in the module block. This temporary structure m be regarded as a "negative" of the module block, in the sense that whee the temporary structure has substance, the module block will have space, aro vice versa. In the preferred technique in accordance with the inventio, the temporary structure, produced by the stereolithography technique refelX, t) includes not only a first part, indicated at 50, which defines the iltalmal passages in the finished casting, but also an open-topped box or extemalo,:,uld ! 1 52, integral with the part 50, and containing the part 50, the box 52 deOi iing, for example, a rectangular mould cavity encompassing the part 50, as sho, Im in. Figures 2 and 3. The integral mould box 52 thus supports and locates thiel pait 50 with respect to the mould.

It will be understood that the invention does not require the il( j stereolithography or even computer-aided design for the production of the temporary structure. Thus, the temporary structure could be produc( by machining a block of readily soluble or ablatable material, for example',, 7 computer control, or even by carving such a block manually, or by any other convenient method.

It will be understood that in Figures 2 and 3, the total temporary structure 50, 52 is illustrated in only a very simple form. In practical arrangements, a more complex network of passages and chambers may be present for example a network such as that illustrated in Figure 1. The reference 54, in Figures 2 and 3 represents a chamber, whilst references 56 indicate connecting passages, or rather reference 54 indicates a block of the selected readily soluble (or otherwise readily ablatable) material which will define a chamber in the finished manifold block whilst references 56 indicate rods or stalks of the selected readily soluble or ablatable material which will define corresponding passageways in the firtished manifold block. The parts 54 and 56 are, of course, respective portions of the part 50. The chambers represented in "negative" form by solid features in the temporary structure 50 may be adapted to define, in the flnished module block, housings or cavities of appropriate shape for such components as valves, pressure regulators, or the like, so that such components can be wholly or partially incorporated in the finished module block, instead of being mounted on an outer surface of the block as is conventional. Thus, for example, the inside form of the body of a pressure regulator may be reproduced completely in the cast block, so that it is only necessary to add the internal components and a cover.

Reverting to the stage illustrated in Figures 2 and 3, the temporary solid structure 50, 52, is next placed in a vacuum chamber and a liquid synthetic resin material is poured, under vacuum, into the mould cavity to fill the same (see Figure 4). The resin is then allowed to cure and/or harden (see Figure 5) after which the whole item, including the mould box 52 and the moulded synthetic resin block, is washed in the appropriate solvent to dissolve away the 8 mould 52 and the inclusions 50 within the moulded block, washing the so] 4bl material out through the internal passages. (It will be understood, of wi Tse, that the solvent selected must be one which will not dissolve, at least -to any significant extent, the synthetic resin of the block). (Where the temperar( structure is intended to be ablated by some method other than dissolutioO: 1hat other method is, of course, used in place of the above dissolving step)','t, 111. resultant plastics manifold block is illustrated in Figure 6. The plastics1b ocl C can now be finished as required prior to mounting the various components and connectors, etc. thereon.

It will be appreciated that the technique described can be applied usir! appropriate mouldable material for the block and any appropriate sl ible material or otherwise readily ablatable material for the temporary structu,,Ie, thc primary requirement being that the temporary structure should be cap I of maintaining its integrity during moulding of the mouldable material and ',v i il s t the latter sets or hardens and should be capable of being removed fro' th resulting product in an easy and straightforward way without darnagi! i g lth,moulding product. It will be understood that the technique used, e.$. it solvent used, where -the temporary structure is to be dissolved, will 40 en't upon the material used for the temporary structure.

The liquid synthetic resin material poured into the mould to form the bloc] 513 may be, for example, a plastics casting compound such as polyureth#! tw epoxy resin, the liquid casting resin being formed by mixing 1) components of a two-component, plastics resin/hardener system, the resj and hardener being mixed, immediately before casting, in the appropriate ralfo an at the recommended temperature, preferably in a vacuum environment.

9 Manifold blocks manufactured in accordance with the invention, being unitary components, are stronger than conventional mulfi-part manifold blocks, since there are no joints to be made and no glue or connectors required to hold discrete parts together. Such manifold blocks are furthermore better able to withstand thermal stresses, since there is no joint to fail. The higher strength of the product makes it possible to make such manifold blocks of smaller and lighter construction for comparable applications since the unitary modules have a higher strength than modules of conventional construction and thus require lesser wall thicknesses etc. The technique proposed is simple and involves reduced cost and time for manufacture. In particular, the minimum time required from design to production can be reduced and prototypes, or small batches or "one-off' modules can be produced without difficulty. The method can be carried out without dedicated tooling, allowing changes in design to be made rapidly and inexpensively. Conversely, of course, where large production runs are envisaged, it may be economically attractive to produce, for example, re-usable moulds for the temporary structure, so that it is not necessary to form each temporary structure by stereolithography.

As an additional advantage, as compared with the conventional crossdrilling technique referred to above, the method of the invention is not limited to the production of arrangements in which bores or passages in the manifold or block produced meet at abrupt angles or comers, but can be used to produce passages having gradual bends and smooth junctions to optimise the fluid flow paths through the manifold block and hence reduce unwanted pressure drops within the module. Another advantage is that the process eliminates the risk of burrs associated with the conventional cross-drilling technique.

In the present specification "comprise" means "includes or consists of' and "comprising" means "including or consisting of'.

The features disclosed in the foregoing description, or the following clain'. or the accompanying drawings, expressed in their specific forms or in term's of a

P means for performing the disclosed function, or a method or procos., fo r attaining the disclosed result, as appropriate, may, separately, or ainy combination of such features, be utilised for realising the invention in i,,ere forms thereof.

Claims (9)

1. A method of manufacturing a manifold or fluid connection block comprising forming a structure, in a first solid material, which corresponds in configuration to the desired configuration of passages and/or chambers in the manifold, supporting said structure within a mould, then filling the mould with a second material in liquid or flowable condition, to encompass at least a desired portion of said structure, causing or allowing said second material to solidify to form the manifold block, and subsequently removing said first material to leave the desired passageways and/or chambers in the block.

2. A method according to claim 1, wherein said second material is a curable synthetic resin or other castable material.

3. A method according to claim I or claim 2 wherein first solid material forming said structure is a soluble or ablatable material which is removed, after solidification of said second material, by dissolving in a solvent for said first solid material, or by otherwise ablating the first material, for example by heating.

4. A method according to any preceding claim, wherein said structure of said first material is formed directly from a 3-D computer model.

5. A method according to any preceding claim wherein said structure of said first material is fonned by a stereolithographic technique.

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6. A method according to any preceding claim wherein said st", #ure includes elements adapted to define, in the cast manifold block, a hou$, Ii)r other component or components of a device, such as a valve or pf..,. e;$U.e regulator, to be incorporated wholly or partly in the block.

7. A method of manufacturing a component incorporating i#t.-grd passageways or chambers comprising forming a structure, in a firsfi, I'd o material, which has at least a portion which corresponds in configuratiop 14 the desired configuration of passages or chambers in the component, sup c rtir g said portion in a mould, then filling the mould with a second maten#1 in a liquid or flowable condition to encompass said portion, causing or alj Alirg said second material to solidify to form the desired componen and subsequently removing said first material to leave the desired passag'PI a3 s and/or chambers in the component.

8. A method according to any preceding claim wherein the mould io i self formed of said first material and is integral with the structure, in saAO first material, defining the desired configuration of passages or chambers.

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9. A method substantially as hereinbefore described with reference;t( accompanying drawings.