Mould core, production method, fitting body and device for producing the fitting body
Patent Information
- Application Number
- EP2024703945
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-29
- Filing Date
- 2024-02-05
- Publication Date
- 2026-02-11
AI Technical Summary
Existing manufacturing processes for process fittings, such as metal casting and plastic injection molding, face challenges in producing fittings with precise internal and external sealing sections and fluid flow optimization, often resulting in high manufacturing tolerances and material inefficiencies.
A lost mold core with integrated inner and outer sealing negative sections, channel sections, and a reference section is used to produce fittings with optimized internal surfaces and fluid flow, allowing for reduced tolerances and improved flow efficiency, and can be made from thermally deformable materials like ABS or Wood's metals for easy removal and reuse.
The solution enables the production of fittings with reduced manufacturing tolerances, improved fluid flow efficiency, and enhanced environmental compatibility by using a mold core that can be quickly and cost-effectively produced and reused, while minimizing material waste and ensuring precise sealing sections.
Smart Images
Figure EP2024052745_03102024_PF_FP_ABST
Abstract
Description
[0001] Title : Mould core , manufacturing process , valve body and
[0002] Device for producing the valve body
[0003] Description
[0004] The invention concerns advances in the field of process valve manufacturing.
[0005] Various processes are known for the production of process valves, such as metal casting and plastic injection molding with drop cores.
[0006] The problems of the prior art are solved by a mold core according to claim 1, by a manufacturing method according to a subordinate claim, by a
[0007] This object is achieved by a valve body according to a further claim and by a device for producing the valve body according to another claim. Advantageous further developments can be found in the subclaims, the following description, and the drawing.
[0008] A first aspect of the description relates to the following subject matter: A lost mold core for producing a valve body for a process valve comprising at least one main section comprising an inner sealing negative section which provides a negative contour for an inner sealing section of the valve body to be produced; and at least two channel negative sections protruding from the main section on both sides of the inner sealing negative section, which channel negative sections each provide a negative contour for an associated channel section of the valve body to be produced.
[0009] This process transforms an inner contour into the outer contour for the production of the mold core. This advantageously allows the production of separation residue-free and aerodynamically optimized inner surfaces of the valve body using the lost mold core.
[0010] An advantageous example is characterized in that the main section comprises a circumferential outer sealing negative section, which provides a negative contour for an outer sealing section of the fitting body to be produced.
[0011] The joint, particularly one-piece realization of the outer and inner negative sealing sections in the mold core ensures that the manufacturing tolerances with regard to the positions of the inner and outer sealing sections of the process valve are reduced during the manufacturing process.
[0012] An advantageous example is characterized in that the inner sealing negative section and the outer sealing negative section are aligned in opposite directions.
[0013] This makes it possible to advantageously produce a valve body in the sense of the fitting body for a diaphragm valve.
[0014] Of course, other valve bodies can also be manufactured using the proposed methods.
[0015] An advantageous example is characterized in that at least one of the channel negative sections tapers in its course, starting from the main section, in the direction of a round cross section of the associated channel negative section in a section, in particular in a section perpendicular to the course of the inner sealing section, at least in sections.
[0016] This allows for aerodynamically advantageous solutions in the connection between the web-shaped seat section and the pipe section with a round cross-section. In particular, this allows for oval or other shaped cross-sections in the inlet and outlet areas of the seat, which reduce flow resistance and pressure loss.
[0017] An advantageous example is characterized in that at least one of the channel contour negative sections has, at least in sections, a surface negative structure with alternating projections and recesses, wherein the projections and recesses provide negative contours for an internal flow structure of the associated channel section of the fitting body to be produced.
[0018] Advantageously, flow structures can be introduced into the interior of the valve body in a simple manner.
[0019] An advantageous example is characterized in that the main section comprises a reference section opposite the inner sealing negative section for bearing against an ejection side of a molding tool.
[0020] The reference section can advantageously be used to reduce manufacturing tolerances and deviations.
[0021] An advantageous example is characterized in that the mold core comprises an outer shell delimiting an interior space.
[0022] The outer shell advantageously ensures the dimensional stability required during transfer injection molding of the fitting body, whereby material quantities for the mold core can be saved.
[0023] A further advantage is the faster dissolution of the material, since, on the one hand, less material from the molded body needs to be removed. On the other hand, dissolving or washout liquid can be introduced through openings leading into the interior of the mold core to wash out the mold core.
[0024] An advantageous example is characterized in that the interior is filled with a further filling material which is different from the first material of the mold core.
[0025] Advantageously, the additional material, for example sand or other suitable materials, can be reused in the manufacturing process, which improves the environmental compatibility of the process.
[0026] An advantageous example is characterized by the fact that the interior is not filled.
[0027] This advantageously allows for faster washing out or dissolution of the mold core—assuming the outer shell remains dimensional stable. Cycle time is reduced.
[0028] A second aspect of the description relates to the following subject matter: A method for producing a valve body for a process valve, comprising producing at least one mold core, in particular according to the first aspect, from at least one first material; fixing the at least one produced mold core in a mold, wherein a cavity is delimited by the at least one mold core and an inner contour of the mold; introducing a plastic melt of at least one second material into the cavity to produce the valve body from the at least one second material; removing the mold core from the produced valve body.
[0029] The removable plastic mold core advantageously improves the manufacturing of the plastic valve body. The dependence of the valve body's internal geometry on its demoldability is reduced, thus eliminating the need for complex drop cores, for example.
[0030] The reduced dependence on the deformability enables new internal contours and thus the possibility of improving the flow efficiency of the process fluid within the valve body , in particular the flow coefficient or K v -value to improve.
[0031] An advantageous example is characterized by the fact that the mold core or a part of the mold core is manufactured using a plastic injection molding process. Advantageously, this method allows a large number of disposable mold cores to be produced quickly and cost-effectively.
[0032] An advantageous example is characterized in that the first material comprises at least one of the following materials: acrylonitrile butadiene styrene, ABS, polyvinyl alcohol, PVA, and polyvinyl butyral, PVB.
[0033] ABS is advantageously thermally stable. The surfaces can be machined, for example, by milling. It is available as a bar stock. The ABS molded body can be easily removed from the fitting body using acetone.
[0034] PVA can be easily released from the fitting body using water.
[0035] PVB can be easily removed from the fitting body using alcohol.
[0036] An advantageous example is characterized in that the fixing of the at least one produced mold core comprises the insertion of at least one holder into the mold core, wherein the at least one holder presses the reference section onto an ejection-sealable section of the molding tool. This type of fixing advantageously improves the manufacturing process reliability of the contours for the inner and outer sealing sections of the fitting.
[0037] An advantageous example is characterized in that at least one feed channel arranged in a nozzle-side section of the mold for introducing the plastic melt opens into the cavity in a region of the cavity facing the inner negative sealing section.
[0038] Advantageously, the plastic melt is guided into the cavity in the area which forms, provides or supports the later inner sealing section or valve seat of the valve body.
[0039] A further advantageous example is characterized in that the first material has a melting point below a melting point of the second material.
[0040] Advantageously, the mold core can be liquefied or at least deformed by applying thermal energy. This allows the valve body to be easily removed from the mold core.
[0041] Wood's metals, for example, are suitable for this purpose, as they have a melting point lower than that of many thermoplastics. Thermal removal of the mold core allows the material from the mold core to be reused for the production of a new one.
[0042] An advantageous example is characterized in that in order to remove the mold core, a washout liquid is introduced into an interior region of the valve body in order to wash out the mold core.
[0043] Advantageously, the valve body with the mold core can be placed in a bath containing the washout liquid.
[0044] Alternatively or additionally, the washout liquid can be introduced under pressure into the interior of the valve body.
[0045] An advantageous example is characterized in that the second material comprises a plastic material, in particular a thermoplastic such as polyvinylidene fluoride, PVDF or polypropylene, PP.
[0046] The use of plastic is particularly advantageous for high-purity process media that must be protected from unwanted contamination such as metal ions.
[0047] An advantageous example includes machining of the outer
[0048] Sealing section of the manufactured valve body. Machining, in particular turning, the outer sealing section advantageously improves its surface quality and reduces surface roughness. Accordingly, the sealing body, for example a membrane in the outer sealing section, meets a surface that ensures a defined and secure seal of the process valve to the outside.
[0049] A third aspect of the description relates to the following subject matter: a fitting body which is manufactured by means of the method according to the second aspect.
[0050] A fourth aspect of the description relates to the following subject matter: A device for producing a fitting body for a process fitting, comprising a first machine for producing at least one mold core, in particular according to the first aspect, from at least one first material; a molding tool for fixing the at least one produced mold core therein, wherein a cavity is delimited by the at least one mold core and an inner contour of the molding tool; the molding tool for introducing a plastic melt of at least one second material into the cavity for producing the fitting body from the at least one second material; and a second machine for removing the mold core from the produced fitting body.
[0051] The drawing shows:
[0052] Figure 1 shows a mold core in a section; Figure 2 shows a fitting body produced using the mold core;
[0053] Figure 3 shows a molding tool shown in a schematic section with a mold core fixed therein for producing the valve body; and
[0054] Figure 4 is a schematic flow diagram.
[0055] Figure 1 shows a mold core 100 for producing a fitting body 200, which is shown in Figure 2. Reference is made below to Figures 1 and 2.
[0056] The lost mold core 100 for producing the valve body 200 for a process valve comprises at least one main section 102 comprising an inner sealing negative section 104, which provides a negative contour for an inner sealing section 204 of the valve body 200 to be produced. The mold core 100 comprises at least two channel negative sections 110, 120 protruding from the main section 102 on both sides of the inner sealing negative section 104, each of which provides a negative contour for an associated channel section 210, 220 of the valve body 200 to be produced.
[0057] The inner sealing negative section 104 can also be referred to as a seat negative section or valve seat negative section. Accordingly, the inner sealing section 204 of the valve body 200 can also be referred to as a seat section or valve seat section.
[0058] The sections referred to in this description as 'negative sections' of the mold core 100 form a contour that is enclosed by the plastic melt in the subsequent injection molding process. Thus, the respective negative section can also be referred to as a mold core section, for example, a sealing mold core section.
[0059] The mold core 100 is referred to as 'lost' because it is removed from the fitting body 200 after injection molding or injection-compression molding. This can be done by dissolving it using a liquid that dissolves the material of the mold core, i.e., by washing out the mold core 100, or by mechanically machining the mold core 100, for example, blasting or pulling out an elastic core.
[0060] At least one of the channel negative sections 110, 120 has a curved section pointing away from the main section 102 in its course and then merges into a pipe section which is round in cross section and runs along an imaginary central longitudinal axis.
[0061] The main section 102 comprises a circumferential outer sealing negative section 106, which provides a negative contour for an outer sealing section 206 of the valve body 200 to be produced. In the example, the outer sealing section 206 of the valve body 200 comprises a raised section relative to the surface surrounding the sealing section 206. In the present case, the raised section of the outer sealing section 206 is annular.
[0062] The inner seal negative section 104 and the outer seal negative section 106 are oriented in opposite directions. A first normal vector of the inner seal negative section 104 thus points in a direction opposite to a second normal vector of the outer seal negative section 106.
[0063] A valve membrane of a diaphragm valve (not shown in Figure 2) closes with its lateral region an opening 230 exposing the inner sealing section 204 or seat. By moving the membrane by means of a drive along the actuating axis S, the diaphragm valve is opened or closed.
[0064] At least one of the channel negative sections 110, 120 tapers at least in sections in its course starting from the main section 102 in the direction of a round cross-section of the associated channel negative section 112, 122 in a section, in particular in a section AA perpendicular to the course of the inner sealing negative section 104, which runs through an imaginary adjusting axis S of the process valve. A taper in the shown section AA is shown schematically according to the lines 111, 121. At least one of the channel contour negative sections 110 has, at least in sections, a surface negative structure 114 with projections and recesses, wherein the projections and recesses provide negative contours for an internal flow structure 214 of the associated channel section 210. In the example, the surface negative structure 114 runs circumferentially, thus following the inner surface of a cylinder jacket.Alternatively, the negative surface structure 114 or the inner flow structure 214 can also be provided only in a closed, non-circumferential area of the inner wall.
[0065] The illustrated drop-shaped contours of the mold core 100 can be designed as projections or recesses in order to be realized as drop-shaped recesses or projections on the inner wall of the channel section 210. A preferred flow direction V is predetermined by the tapering direction of the drop shape. The drop shape in the channel section 210 improves the cleanability of the internal geometry in the region of the channel section 220.
[0066] By incorporating a surface structure, the convective heat transfer between the valve body and the process medium can also be increased. This offers advantages when heating or cooling using fluids.
[0067] Of course, differently contoured
[0068] Flow structures 214 can be realized by means of the correspondingly contoured negative surface structure 114. For example, recessed dimples or dents can be formed in the flow structure 214 in order to specifically influence the flow of the process fluid within the manufactured valve body 200.
[0069] The main section 102 comprises a reference section 108 opposite the inner sealing negative section 104 for abutting against an ejection side of a molding tool. The reference section 108 is contoured and comprises one or more slots into which a counter contour of the molding tool engages.
[0070] In comparison to the prior art, the mold core 100 enables, for example, the manufacture of the fitting body 200 with an internal free space 216, 226, which cannot be easily manufactured by means of simple slides in injection molding or requires complexly constructed drop cores.
[0071] The examples shown refer to the production of a valve body for a diaphragm process valve. Of course, the described processes can also be applied to more complex valve blocks with several differently designed valve sections and to other process valves such as butterfly valves or seat valves.
[0072] The soluble or removable mold core offers the advantage that it does not have to be demolded, but is dissolved in the solidified plastic injection molded part. For example, PVA is a water-soluble plastic that can be used for the mold core. Furthermore, there is the possibility of producing the core from a material such as Wood's metal, for example a bismuth alloy. Here the melting temperature is below 100 ° C and the core is removed from the mold by changing the aggregate state.
[0073] Plastic injection molded part released (bismuth alloy).
[0074] Figure 3 shows a schematic section of the mold 300 for injection molding or injection-compression molding of the fitting body 200 from Figure 2. The mold core 100 is fixed in the mold 300.
[0075] The fixing of the at least one manufactured mold core 100 comprises the insertion of at least one holder 320, 322 into the mold core 100, wherein the at least one holder 320, 322 presses the reference section 108 onto an ejection section 330 of the molding tool 300.
[0076] A cavity 310 is delimited by the outer contour of the at least one mold core 100 and an inner contour of the molding tool 300, in particular by the ejection-side section 330 and the nozzle-side section 340 of the molding tool 300.
[0077] At least one in the nozzle-side section 340 of the
[0078] Feed channel 342 arranged in the molding tool 300 for the
[0079] Introduction 406 of the plastic melt flows into the cavity 310 in a region of the cavity 310 facing the inner sealing negative section 104 of the mold core 100.
[0080] After the plastic melt has solidified in the cavity 310, the manufactured fitting body with the mold core 100 arranged therein is ejected from the mold 300.
[0081] The mold core 100 shown comprises an outer shell 160 defining an interior space 150. In the example shown, the interior space 150 is used during injection molding of the valve body to insert the slides or holders 320 and 322. The interior space 150 is accessible via two openings, allowing washout fluid to be passed under pressure through the mold core 100. In the example shown, the interior space 150 is not filled.
[0082] In an example not shown, the interior space 150 is filled with a further filling material different from the first material of the mold core 100.
[0083] In one example, the outer shell 160 is inflated in one inflation step and then filled with the filling material. This reduces cycle time and enables recycling of the filling material.
[0084] Figure 4 shows a schematic flow diagram of the manufacture of the valve body. A device 400 for manufacturing the valve body is also shown schematically. The device 400 comprises a first machine 420 for
[0085] Producing 402 the at least one mold core from at least one first material.
[0086] The manufacture 402 of the mold core or a part of the mold core is carried out by a plastic injection molding process or a plastic injection compression molding process.
[0087] In another example, the mold core or a portion of the mold core is manufactured using an additive manufacturing process. This is particularly advantageous for constructing prototypes of the valve body.
[0088] The first material for the mold core comprises, for example, at least one of the following materials: acrylonitrile butadiene styrene, ABS, polyvinyl alcohol, PVA, and polyvinyl butyral, PVB.
[0089] The first material has a melting point below a melting point of the second material for the valve body.
[0090] After the mold core has been produced 402, the mold tool 300 is controlled or configured in such a way as to fix the at least one produced mold core therein 404.
[0091] The plastic melt made from granules and made of at least one second material is introduced 406 into the cavity by means of the molding tool 300 in order to produce the fitting body from the at least one second material. The introduction 406 takes place after the fixing 404.
[0092] The second material comprises a plastic material, in particular a thermoplastic such as polyvinylidene fluoride, PVDF, or polypropylene, PP.
[0093] A second machine 480 is configured to remove 408 the mold core from the manufactured valve body. Removal 408 takes place after insertion 406.
[0094] To remove 408 the mold core, a washout liquid is introduced into an interior area of the valve body in order to wash out the mold core.
[0095] Alternatively or additionally, particles blown onto the mold core can remove the mold core.
[0096] Another machine 490 is configured for machining 410 the outer sealing section of the manufactured valve body. This step is optional and can be omitted depending on the design of the previous steps.
Claims
Patent claims 1. A lost mold core (100) for producing a valve body (200) for a process valve, comprising: at least one main section (102) comprising an inner sealing negative section (104) which provides a negative contour for an inner sealing section (204) of the valve body (200) to be produced; and at least two channel negative sections (110, 120) projecting from the main section (102) on both sides of the inner sealing negative section (104), each of which has a negative contour to an associated channel section (210, 220) of the valve body (200) to be manufactured.
2. The mold core (100) according to claim 1, wherein the main portion (102) comprises a circumferential outer sealing negative portion (106) which provides a negative contour for an outer sealing portion (206) of the fitting body (200) to be produced.
3. The mold core (100) according to the preceding claim, wherein the inner sealing negative section (104) and the outer sealing negative section (106) are oriented in opposite directions.
4. The mold core (100) according to one of the preceding claims, wherein at least one of the channel negative sections (110, 120) extends in its course starting from the main section (102) in the direction of a round cross section of the associated channel negative section (112, 122) in a section, in particular in a Course of the inner sealing section (104) vertical section (AA), tapered at least in sections.
5. The mold core (100) according to one of the preceding claims, wherein at least one of the channel contour negative sections (110) has, at least in sections, a surface negative structure (114) with projections and recesses, wherein the projections and recesses provide negative contours for an internal flow structure (214) of the associated channel section (210).
6. The mold core (100) according to any one of the preceding claims, wherein the main portion (102) comprises a reference portion (108) opposite the inner sealing negative portion (104) for abutting against an ejection side of a molding tool.
7. The mold core (100) according to one of the preceding claims, wherein the mold core (100) comprises an outer shell (160) delimiting an interior space (150).
8. The mold core (100) according to the preceding claim, wherein the interior space (150) is connected to a further space from the first Material of the mold core (100) is filled with different filling material.
9. The mold core (100) according to one of claims 1 to 7, wherein the interior space (150) is not filled.
10. A method for manufacturing a valve body (200) for a process valve comprising: Producing (402) at least one mold core (100), in particular according to one of the preceding claims, from at least one first material; Fixing (404) the at least one manufactured mold core (100) in a mold (300), wherein a cavity (310) is delimited by the at least one mold core (100) and an inner contour of the mold (300); Introducing (406) a plastic melt of at least one second material into the cavity (310) to produce the fitting body (200) from the at least one second material; Removing (408) the mold core (100) from the manufactured fitting body (200).
11. The method according to claim 10, wherein the manufacture of the mold core (100) or a part of the mold core (100) is carried out by a plastic injection molding process.
12. The method according to any one of claims 10 to 11, wherein the first material comprises at least one of the following materials: acrylonitrile butadiene styrene, ABS, polyvinyl alcohol, PVA, and polyvinyl butyral, PVB.
13. The method according to one of claims 10 to 12, wherein the fixing (404) of the at least one manufactured mold core (100) comprises inserting at least one holder (320, 322) into the mold core (100), and wherein the at least one holder (320, 322) presses the reference section (108) onto an ejection section (330) of the molding tool (300).
14. The method according to one of claims 10 to 13, wherein at least one feed channel (342) arranged in a nozzle-side section (340) of the mold (300) for introducing (406) the plastic melt opens into the cavity (310) in a region of the cavity (310) facing the inner negative sealing section (104).
15. The method according to any one of claims 10 to 14, wherein the first material has a melting point below a melting point of the second material.
16. The method according to one of claims 10 to 15, wherein for removing (408) the mold core (100) a washout liquid is introduced into an interior region of the fitting body (200) in order to wash out the mold core (100).
17. The method according to any one of claims 10 to 16, wherein the second material comprises a plastic material, in particular a thermoplastic such as polyvinylidene fluoride, PVDF or polypropylene, PP.
18. The method according to any one of claims 10 to 17 comprising: Machining (410) the outer sealing section (206) of the manufactured valve body (200).
19. A fitting body (200) manufactured by the method according to one of claims 10 to 18.
20. A device for producing a valve body (200) for a process valve, comprising: a first machine (420) for producing (402) at least one mold core (100), in particular according to one of claims 1 to 9, from at least one first material; a molding tool (300) for fixing (404) the at least one produced mold core (100) therein, wherein a cavity (310) is delimited by the at least one mold core (100) and an inner contour of the molding tool (300); the molding tool (300) for introducing (406) a plastic melt of at least one second material into the cavity (310) to produce the fitting body (200) from the at least one second material; a second machine (480) for removing (408) the mold core (100) from the produced fitting body (200).