Core, production method, valve body and device for producing valve body

Abstract

The invention relates to a lost mold core (100) for producing a valve body (200) for a process valve, said core comprising: at least one main part (102) comprising an inner sealing female part (104) providing a female profile for an inner sealing part (204) of the valve body (200) to be produced; and at least two channel female portions (110, 120) projecting from the main portion (102) on both sides of the inner sealing female portion (104) and each providing a female profile for an assigned channel portion (210, 220) of the valve body (200) to be produced.

Description

[0001] The invention relates to an improvement of production process valves.

[0002] Various methods are known for producing process valves, such as metal casting and injection molding with core pulling of plastics.

[0003] The problem of the prior art is solved by the core according to claim 1, by the production method according to an independent claim, by the valve body according to another claim and by the device for producing a valve body according to another claim. Advantageous refinements can be found in the dependent claims, the following description and the drawings.

[0004] A first aspect of the present description relates to the following subject matter: A core for producing a valve body for a process valve, the core comprising at least one main portion, the at least one main portion comprising an inner sealing female portion providing a female contour for an inner sealing portion of the valve body to be produced, and at least two channel female portions, the at least two channel female portions protruding from the main portion on both sides of the inner sealing female portion and each providing a female contour for a distributed channel portion of the valve body to be produced.

[0005] The method transforms an inner contour into an outer contour for producing a core. Advantageously, the core allows the production of a valve body with a separate, residue-free and flow-optimized inner surface.

[0006] One advantageous example is characterized in that the main portion comprises a circumferential outer sealing female portion providing a female contour for an outer sealing portion of the valve body to be produced.

[0007] The combination, in particular the integration, of the outer sealing female portion and the inner sealing female portion in the core achieves an ensured reduction of manufacturing tolerances with regard to the position of the inner sealing portion and the outer sealing portion of the process valve during the production process.

[0008] One advantageous example is characterized in that the inner sealing female portion and the outer sealing female portion are oriented in opposite directions.

[0009] Advantageously, this allows the production of a valve body similar to a valve body for a diaphragm valve.

[0010] Of course, other valve bodies can also be produced by means of the proposed method.

[0011] One advantageous example is characterized in that at least one of the channel female portions tapers at least partially in cross section, starting from the main portion, in the direction of a circular cross section of the distributed channel female portion, the cross section being in particular perpendicular to the course of the inner sealing female portion.

[0012] This allows to achieve a fluidically advantageous solution in the connection between the mesh seat portion and the tube portion having a circular cross section. In particular, this allows an elliptical or differently shaped cross section in the inflow and outflow areas of the seat, which reduces the flow resistance and pressure loss.

[0013] One advantageous example is characterized in that at least one of the channel profile recesses at least partially has a surface recess structure having alternating protrusions and recesses, wherein the protrusions and recesses provide a recess profile for the internal flow structure of the assigned channel portion of the valve body to be produced.

[0014] Advantageously, this allows to easily introduce a flow structure into the interior of the valve body.

[0015] One advantageous example is characterized in that the main portion comprises a reference portion opposite the inner sealing recess portion for contacting an ejection side of a mold.

[0016] The reference portion can advantageously reduce manufacturing tolerances and deviations.

[0017] One advantageous example is characterized in that the core comprises a shell delimiting an interior space.

[0018] Advantageously, the shell ensures the required dimensional stability during the transfer injection molding of the valve body while saving the amount of material used for the core.

[0019] Another advantage is a faster release of the material, since less material needs to be removed from the molded body. Secondly, a solvent or washing liquid can be introduced through an opening to the interior space of the core to wash the core.

[0020] One advantageous example is characterized in that the interior space is filled with another filling material different from the first material of the core.

[0021] Advantageously, the additional material, such as sand or other suitable material, can be reused in the production process, which improves the environmental compatibility of the method.

[0022] One advantageous example is characterized in that the interior space is not filled.

[0023] This can advantageously speed up the washing or dissolving of the core - provided the shell is dimensionally stable. Reduces cycle times.

[0024] A second aspect of the present description relates to the following subject matter: A method for producing a valve body for a process valve, the method comprising the following steps: producing at least one core from at least one first material, in particular a core according to the first aspect; fixing the produced at least one core in a mold, wherein a cavity is delimited by the at least one core and an inner contour of the mold; introducing a molten plastic of at least one second material into the cavity for producing the valve body from the at least one second material; removing the core from the produced valve body.

[0025] The production of plastic valve bodies is advantageously improved by the removable plastic core. For example, the dependency of the internal geometry of the valve body on the demolding of the valve body is reduced, for example eliminating the need for complex core pulling.

[0026] The reduced dependency on demolding allows for novel internal contours and thus for the possibility of improving the flow efficiency of process fluids within the valve body, in particular the flow coefficient or K v value.

[0027] One advantageous example is characterized in that the core or a part of the core is produced by means of plastic injection molding.

[0028] Advantageously, a plurality of cores can be produced quickly and cost-effectively in this way.

[0029] One 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).

[0030] Advantageously, ABS is thermally stable. Surfaces can be machined, for example milled. It can be used as a bar stock. ABS moldings can be easily removed from the valve body using acetone.

[0031] PVA can be easily removed from the valve body using water.

[0032] PVB can be easily removed from the valve body using ethanol.

[0033] One advantageous example is characterized in that the fixing of the produced at least one core comprises the insertion of at least one retainer into the core, wherein the at least one retainer presses the reference portion onto the knockout side portion of the mold.

[0034] This type of fixing advantageously improves the production process reliability of the contours of the inner sealing portion and the outer sealing portion for the valve.

[0035] One advantageous example features that at least one feed channel for introducing the molten plastic and arranged in a nozzle side portion of the mold opens into the cavity in a region of the cavity facing the inner sealing portion of the valve body.

[0036] Advantageously, the molten plastic is guided into the cavity in the region, which later will form, provide or support the inner sealing portion or valve seat of the valve body.

[0037] Another advantageous example features that the first material has a melting point below the melting point of the second material.

[0038] Advantageously, the core can be liquefied or at least deformed by adding thermal energy. This allows the valve body to be easily detached from the core.

[0039] For example, Babbitt metal is suitable for this purpose, as it has a melting point below the melting point of many thermoplastic plastics.

[0040] The thermal removal of the core allows the core material to be reused to produce new cores.

[0041] One advantageous example features that a washing liquid is introduced into an inner region of the valve body to wash the core.

[0042] Advantageously, the valve body with the core can be placed in a bath containing the washing liquid.

[0043] Alternatively or additionally, the washing liquid can be introduced into the inner region of the valve body under pressure.

[0044] One advantageous example features that the second material comprises a plastic material, in particular a thermoplastic, such as polyvinylidene fluoride (PVDF) or polypropylene (PP).

[0045] The use of plastic is particularly advantageous for high-purity process media that must be protected from harmful contamination, such as the intrusion of metal ions.

[0046] One advantageous example comprises machining the outer sealing portion of the valve body produced.

[0047] Machining, in particular turning, the outer sealing portion advantageously improves its surface quality and reduces surface roughness. Accordingly, the surface that the sealing body, for example the diaphragm in the outer sealing portion, contacts ensures a clear and firm sealing of the process valve from the outside.

[0048] A third aspect of the present description relates to the subject matter of a valve body produced by the method according to the second aspect.

[0049] A fourth aspect of the present description relates to the following subject matter: An apparatus for producing a valve body for a process valve, the apparatus comprising: a first machine for producing at least one core from at least one first material, in particular a core according to the first aspect; a mold for fixing the produced at least one core therein, wherein a cavity is delimited by the at least one core and an inner contour of the mold; the mold for introducing a molten plastic of at least one second material into the cavity for producing the valve body from the at least one second material; and a second machine for removing the core from the produced valve body.

[0050] In the drawings: Figure 1 A cross section of a core is shown; Figure 2 A valve body produced using the core is shown; Figure 3 is a schematic cross-sectional view of a mold in which a core for producing the valve body is fixed; and Figure 4 A schematic sequence diagram is shown.

[0051] Figure 1 A core 100 for producing a valve body 200 is shown, which valve body is shown in Figure 2 . Reference is made below to Figure 1 and Figure 2 .

[0052] The core 100 for producing a valve body 200 for a process valve comprises at least one main portion 102, which main portion comprises an inner sealing female portion 104, which provides a female contour for an inner sealing portion 204 of the valve body 200 to be produced. The core 100 comprises at least two channel female portions 110, 120, which project from the main portion 102 on both sides of the inner sealing female portion 104 and each provide a female contour for a distribution channel portion 210, 220 of the valve body 200 to be produced.

[0053] The inner sealing female portion 104 can also be referred to as a seat female portion or a valve seat female portion. Correspondingly, the inner sealing portion 204 of the valve body 200 can also be referred to as a seat portion or a valve seat portion.

[0054] In this description, the portions of the core 100 referred to as “female portions” form contours that are surrounded by molten plastic in a subsequent injection molding process. This means that the respective female portion can also be designated as a core portion - for example, a sealing core portion.

[0055] The core 100 is called "lost" because it is removed from the valve body 200 after injection molding or injection compression molding. This can be achieved by dissolving the core using a liquid that dissolves the core material, i.e. by washing the core 100, or by mechanically treating the core 100, for example, by sandblasting or pulling out an elastic core.

[0056] At least one of the channel female parts 110, 120 has a curved portion along its course, which is directed away from the main portion 102 and which then transitions into a tube portion, which has a circular cross section and extends along an imaginary central longitudinal axis.

[0057] The main portion 102 comprises a circumferential outer sealing female part 106, which provides a female contour for an outer sealing portion 206 of the valve body 200 to be produced.

[0058] In this example, the outer sealing portion 206 of the valve body 200 comprises a raised portion opposite the surface surrounding the sealing portion 206. In the present case, the raised portion of the outer sealing portion 206 is annular.

[0059] The inner sealing female part 104 and the outer sealing female part 106 are oriented in opposite directions. Thus, a first normal vector of the inner sealing female part 104 is directed in a direction opposite a second normal vector of the outer sealing female part 106.

[0060] A valve diaphragm (not shown in Figure 2 exposes the inner sealing portion 204 or seat. The diaphragm valve is opened or closed by moving the diaphragm along the actuation axis S by means of a drive.

[0061] At least one of the channel female parts 110, 120 tapers at least partially in cross section along its course, starting from the main portion 102, in the direction of the circular cross section of the assigned channel female part 112, 122, in particular the cross section A-A perpendicular to the course of the inner sealing female part 104 and extending through the imaginary actuation axis S of the process valve. The tapering in the illustrated cross section A-A is schematically indicated according to the lines 111, 121.

[0062] At least one of the channel contour female parts 110 has at least partially a surface female structure 114 having protrusions and recesses, wherein the protrusions and recesses provide a female contour for an inner flow structure 214 of the assigned channel portion 210. In this example, the surface female structure 114 extends circumferentially, thus following the inner surface of the cylindrical sleeve. Alternatively, the surface female structure 114 or the inner flow structure 214 can also be provided only in a closed, non-circumferential region of the inner wall.

[0063] The exemplarily drop-shaped profile of the core 100 can be formed convex or concave to be realized as a drop-shaped concave or convex on the inner wall of the channel portion 210. The preferred flow direction V is determined by the direction of the tapering of the drop shape. The drop shape in the channel portion 210 enhances the cleanability of the inner geometry in the area of the raised channel portion 220.

[0064] The introduction of the surface structure can also increase the convective heat transfer between the valve body and the process medium. This provides an advantage when using a fluid for heating or cooling.

[0065] Of course, flow structures 214 of different profiles can also be realized by corresponding profiled surface counter structures 114. For example, concave pits or indentations can be formed in the flow structures 214 to specifically influence the flow of the process fluid within the produced valve body 200.

[0066] The main portion 102 comprises a reference portion 108 opposite the inner sealing counter portion 104 for contacting the ejection side of the mold. The reference portion 108 is profiled and comprises one or more grooves in which a corresponding profile of the mold engages.

[0067] In comparison to the prior art, the core 100 allows for example the production of valve bodies 200 with inner free spaces 216, 226, which cannot be easily produced using simple sliders in injection molding or require complex core pulling.

[0068] The shown example relates to the production of a valve body for a diaphragm process valve. Of course, the described method can also be applied to more complex valve blocks with several differently designed valve portions and other process valves, such as butterfly valves or seat valves.

[0069] A dissolvable core or a removable core provides the advantage that it does not have to be demolded but is dissolved in the solidified plastic injection molded portion. For example, PVA is a water-soluble plastic that can be used for the core. For example, the core can also be produced from a material such as a Wood's metal, such as a bismuth alloy. In this case, the melting temperature is below 100°C and the core is released from the plastic injection molded portion by a phase change (bismuth alloy).

[0070] Figure 3 A schematic cross section of a mold 300 for injection molding or injection compression molding of a valve body 200 from Figure 2 is shown. The core 100 is fixed in the mold 300.

[0071] The fixing of the produced at least one core 100 comprises an insertion of at least one holder 320, 322 into the core 100, wherein the at least one holder 320, 322 presses the reference portion 108 onto an ejection side portion 330 of the mold 300.

[0072] The cavity 310 is delimited by the outer contour of the at least one core 100 and the inner contour of the mold 300, in particular by the ejector side portion 330 and the nozzle side portion 340 of the mold 300.

[0073] The at least one feed channel 342 arranged in the nozzle side portion 340 of the mold 300 for introducing 406 the molten plastic opens into the cavity 310 in the area of the inner sealing recess 104 of the core 100 facing the cavity 310.

[0074] After the molten plastic within the cavity 310 has solidified, the produced valve body with the core 100 arranged therein is ejected from the mold 300.

[0075] The shown core 100 comprises a shell 160 delimiting an inner space 150. In the shown example, the inner space 150 is used to insert a slider or holder 320 and a holder 322 during injection molding of the valve body. The inner space 150 is accessible via two openings, allowing a washing liquid to be passed through the core 100 under pressure. In the shown example, the inner space 150 is not filled.

[0076] In one example not shown, the inner space 150 is filled with another filling material different from the first material of the core 100.

[0077] In one example, the shell 160 is aerated in an aerating step and then filled with the filling material. This reduces the cycle time and allows recycling of the filling material.

[0078] Figure 4 A schematic sequence diagram for producing a valve body is shown. Also shown is a device 400 for producing a valve body.

[0079] The device 400 comprises a first machine 420 for producing 402 at least one core from at least one first material.

[0080] The production 402 of the core or of a part of the core is carried out by means of plastic injection molding or plastic injection compression molding.

[0081] In another example, an additive manufacturing process is used to produce the core or a part of the core. This is particularly advantageous for building a prototype of the valve body.

[0082] The first material for the core comprises at least one of the following materials, for example: acrylonitrile butadiene styrene (ABS), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0083] The first material has a melting point below the melting point of the second material for the valve body.

[0084] After the core has been produced 402, the mold 300 is controlled or designed to fix 404 the produced at least one core therein.

[0085] By means of the mold 300, a molten plastic of at least one second material made of particles is introduced 406 into the cavity to produce a valve body from said at least one second material. The insertion 406 takes place after the fixing 404.

[0086] The second material comprises a plastic material, in particular a thermoplastic, such as polyvinylidene fluoride (PVDF) or polypropylene (PP).

[0087] A second machine 480 is designed to remove 408 the core from the produced valve body. The removal 408 takes place after the insertion 406.

[0088] To remove 408 the core, a washing liquid is introduced into the inner region of the valve body to wash the core.

[0089] Alternatively or additionally, the particles blown onto the core can ablate the core.

[0090] A further machine 490 is designed to machine 410 the outer sealing portion of the produced valve body. This step is optional and can also be omitted depending on the design of the previous steps.

Claims

1. A lost core (100) for producing a valve body (200) for a process valve, the core comprising: at least one main portion (102), the at least one main portion (102) comprising an inner sealing female portion (104) providing a female contour for an inner sealing portion (204) of the valve body (200) to be produced; and at least two channel female portions (110, 120) protruding from the main portion (102) on both sides of the inner sealing female portion (104) and each providing a female contour for a distributed channel portion (210, 220) of the valve body (200) to be produced.

2. The core (100) according to claim 1, wherein the main portion (102) comprises a circumferential outer sealing female portion (106) providing a female contour for an outer sealing portion (206) of the valve body (200) to be produced.

3. The core (100) according to the preceding claim, wherein the inner sealing female portion (104) and the outer sealing female portion (106) are oriented in opposite directions.

4. The core (100) according to any one of the preceding claims, wherein at least one of the channel female portions (110, 120) tapers at least partially in cross section along its course, starting from the main portion (102), in the direction of the circular cross section of the distributed channel female portion (112, 122), the cross section being in particular a cross section (A-A) perpendicular to the course of the inner sealing female portion (104).

5. The core (100) according to any one of the preceding claims, wherein at least one of the channel contour female portions (110) has at least partially a surface female structure (114) having protrusions and recesses, wherein the protrusions and recesses provide a female contour for an inner flow structure (214) of the distributed channel portion (210).

6. The core (100) according to any one of the preceding claims, wherein the main portion (102) comprises a reference portion (108) opposite the inner sealing female portion (104) for contacting a knockout side of a mold.

7. The core (100) according to any one of the preceding claims, wherein the core (100) comprises a housing (160) delimiting an inner space (150).

8. Core (100) according to the preceding claim, wherein the inner space (150) is filled with another filling material different from the first material of the core (100).

9. The core (100) according to any one of claims 1 to 7, wherein the inner space (150) is not filled.

10. A method for producing a valve body (200) for a process valve, the method comprising the following steps: producing (402) at least one core (100), in particular the core (100) according to any one of the preceding claims, from at least one first material; fixing (404) the produced at least one core (100) in a mold (300), wherein a cavity (310) is delimited by the at least one core (100) and an inner contour of the mold (300); introducing (406) a molten plastic of at least one second material into the cavity (310) to produce the valve body (200) from the at least one second material; removing (408) the core (100) from the produced valve body (200).

11. The method of claim 10, wherein, The core (100) or a part of the core (100) is produced by means of plastic injection molding.

12. The method of any one of claims 10-11, 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 of any one of claims 10-12, wherein, The fixing (404) of the at least one core (100) produced comprises the insertion of at least one holder (320, 322) into the core (100), and wherein the at least one holder (320, 322) presses the reference portion (108) onto an ejection side portion (330) of the mold (300).

14. The method of any one of claims 10 to 13, wherein, At least one feed channel (342) for introducing (406) the molten plastic and arranged in a nozzle side portion (340) of the mold (300) opens into the cavity (310) in a region of the cavity (310) facing the inner sealing female portion (104).

15. The method of any one of claims 10 to 14, wherein, The first material has a melting point below the melting point of the second material.

16. The method of any one of claims 10 to 15, wherein, For removing (408) the core (100), a washing liquid is introduced into an inner region of the valve body (200) to wash the core (100).

17. The method of 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 the steps of: machining (410) an outer sealing portion (206) of the valve body (200) produced.

19. A valve body (200) produced by the method according to any one of claims 10 to 18.

20. An apparatus for producing a valve body (200) for a process valve, the apparatus comprising: a first machine (420) for producing (402) at least one core (100) from at least one first material, in particular a core (100) according to any one of claims 1 to 9; a mold (300) for fixing (404) the at least one core (100) produced in wherein, wherein a cavity (310) is delimited by the inner contour of the at least one core (100) and the mold (300); the mold (300) is for introducing (406) molten plastic of at least one second material into the cavity (310) to produce the valve body (200) from the at least one second material; a second machine (480) for removing (408) the core (100) from the valve body (200) produced.

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