Volute machining process

Abstract

The invention relates to a volute machining process which comprises the following steps: step 1, mold removal and parting: in model software, firstly, a pipe orifice of a volute model is detached to form an independent pipe orifice model, then, a runner surface of a runner of the remaining volute model is extracted, a center line of an inverted buckle of the runner surface is found, and the center line of the inverted buckle of the runner surface is extracted; and the remaining volute model is split into two halves with the plane where the center line is located as a dividing plane, and therefore a first shell model and a second shell model are formed. 2, a first shell is machined according to the first shell model, and a second shell is machined according to the second shell model; 3, a pipe opening is machined according to the pipe opening model; and step 4, processing the assembly. According to the volute machining process, the volute is divided into the three sub-parts to be machined respectively, so that the flow channel can be exposed, the machining precision of the roughness and the profile tolerance of the flow channel can be guaranteed, the machining precision requirement of the volute flow channel is met, meanwhile, the machining efficiency of the volute is improved, and the machining difficulty and cost are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of volute flow channel processing, in particular to a volute processing technology. Background Art

[0002] Because the expansion volute flow channel of the centrifugal compressor is curved and has an undercut structure, in the related technology, even with a high-precision large-scale five-axis machine tool, it is impossible to process the flow channel in one go, and the roughness of the inner flow channel and the envelope surface accuracy of the expansion flow channel formed in one go are also poor, which cannot meet the use requirements. Conventional forms are mostly formed in the form of steel mold casting or 3D printing sand mold, but this method is difficult to meet the requirements of the inner flow channel roughness and contour in one go. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, an embodiment of the present invention proposes a volute processing process, in which the volute is split into three sub-components, namely, a first shell, a second shell and a nozzle, and the three sub-components are processed separately, so that during the processing stage, the flow channel can be exposed, thereby ensuring the processing accuracy of the roughness and contour of the flow channel, meeting the processing accuracy requirements of the volute flow channel, and at the same time improving the processing efficiency of the volute, reducing the processing difficulty and cost.

[0004] A volute processing process according to an embodiment of the present invention comprises the following steps:

[0005] Step 1, demolding and parting: in the model software, firstly, the nozzle of the volute model is separated to form a separate nozzle model, then the flow channel surface of the flow channel of the remaining volute model is extracted, the center line of the undercut of the flow channel surface is found, and the remaining volute model is split into two halves with the plane where the center line is located as the dividing plane, thereby forming a first shell model and a second shell model;

[0006] Step 2, using the following steps to process the first shell according to the first shell model, and to process the second shell according to the second shell model:

[0007] Step 21: firstly process a single blank piece of the first shell body and / or a single blank piece of the second shell body;

[0008] Step 22: machining at least two positioning pin holes on the blank;

[0009] Step 23: Rough machining the blank to remove machining allowance, mill out right-angle edges, leave 1-3 mm, and then perform overall stress relief;

[0010] Step 24: Mill out the base surface, use the base surface for positioning, perform semi-finishing milling, and then perform finishing;

[0011] Step 3: Processing the nozzle according to the nozzle model, processing a stopper on the side of the nozzle connected to the flow channel, and processing a weld on the side of the nozzle away from the flow channel;

[0012] Step 4: Component Processing:

[0013] Step 41: Using the positioning pin hole as a positioning point, buckle the first shell and the second shell, and fix the first shell and the second shell with bolts;

[0014] Step 42: Fix the first shell and the second shell by spot welding, and then remove welding stress;

[0015] Step 43: Using the stopper as a positioning point, connect the pipe port and the welded first shell and second shell, and then weld the pipe port;

[0016] Step 5: Leak detection.

[0017] The volute processing technology of the embodiment of the present invention splits the volute into three sub-components, namely a first shell body, a second shell body and a pipe mouth, and processes them separately. Therefore, during the processing stage, the flow channel can be exposed, thereby ensuring the processing accuracy of the roughness and contour of the flow channel, meeting the processing accuracy requirements of the volute flow channel, and at the same time improving the processing efficiency of the volute and reducing the processing difficulty and cost.

[0018] In some embodiments, in step 1, in the model software, a shadow curve command is used to find the undercut center line of the flow path surface, the center line is optimized, the optimized center line is stretched into a sheet body using a stretch command, and the volute model is split into two halves using a split body select face command.

[0019] In some embodiments, in step 1, after the volute model is split into two halves, a reference plane is established for the two halves of the volute model for splitting, or a stretching command is used to form a sheet for splitting, and after splitting, the multiple split first shell parts are combined into a first shell model through a merge command, and the multiple split second shells are formed into a second shell model.

[0020] In some embodiments, in step 21, based on the dimensional data of the first shell model or the second shell model, the minimum range of the blank of the first shell or the second shell is calculated through theoretical modeling, and a processing allowance of 20-30 mm is added to process the blank single piece of the first shell or the second shell, and then the clamping position structure and process reinforcement ribs are processed on the blank single piece; in steps 22 and 23, the clamping position structure is cooperated with the processing machine tool to clamp the single piece; after step 24, the process reinforcement ribs on the blank single piece are cut off, thereby completing the processing of the first shell or the second shell.

[0021] In some embodiments, in step 22 and step 23, for the processing of the flow channel surface, the contour line of the flow channel on the corresponding first shell model or the second shell model is first extracted in the model software, points are generated on the contour line, and the interval between adjacent points is 0.04-0.06mm. The points are arranged into a processing program of a processing machine tool, and the flow channel surface is processed using the processing program.

[0022] In some embodiments, in step 23, during rough machining, the machining machine tool uses cycle instructions for machining; and / or, in step 24, the machining machine tool uses linear interpolation instructions for finishing and adds tool radius compensation.

[0023] In some embodiments, in step 23 and step 24, a large diameter tungsten steel tool is used for rough machining and semi-finishing milling; in step 24, when semi-finishing the flow path surface, a 0.15-0.25 mm allowance is left before finishing; and / or, in step 24, a diamond turning blade is used for finishing.

[0024] In some embodiments, in step 24, after finishing, a small ball cutter is used to clean the undercut surface and the volute tongue surface in the flow channel.

[0025] In some embodiments, in step 41, before the first shell and the second shell are fastened together, welding grooves are first processed on the first shell and the second shell respectively, and in step 43, when welding the pipe mouth, it is necessary to process welding grooves on the pipe mouth and the first shell and the second shell after fixation, the angle of the groove surface is 30°-60°, and the thickness of the groove edge is greater than or equal to 2mm; and / or, in steps 42 and 43, before welding, the parts are preheated, and the preheating temperature is less than or equal to 150°C.

[0026] In some embodiments, in step 41, the tightening force of the bolts fixing the first shell and the second shell is less than or equal to 6 Nm; and / or, in steps 42 and 43, tungsten inert gas shielded arc welding is used, and the welding stress caused by weld shrinkage is removed after welding is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the flow path surface extracted in step 1 of the volute processing process according to an embodiment of the present invention;

[0028] Figure 2 It is a schematic diagram of the first shell model, the second shell model and the nozzle model separated in step 1 of the volute processing process of the embodiment of the present invention;

[0029] Figure 3is a schematic diagram of a single blank after a right-angle edge is milled out in step 23 in the volute processing process according to an embodiment of the present invention;

[0030] Figure 4 It is a schematic diagram of a clamping structure produced on a blank by a volute processing process according to an embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of extracting the profile of the flow channel and the generated points in the volute processing technology according to an embodiment of the present invention;

[0032] Figure 6 It is a schematic diagram of the welding groove processed on the second casing by the volute processing technology of an embodiment of the present invention.

[0033] Reference numerals:

[0034] First shell model 1, second shell model 2, nozzle model 3, flow channel surface 4, center line 5, right-angle edge 6, process reinforcement rib 7, positioning pin hole 8, second shell 9, process clasp 10, clamping position structure 11, groove 12, second shell blank single piece 13, profile line 14, point 15. DETAILED DESCRIPTION

[0035] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0036] See the attached Figures 1 to 6 The volute processing technology according to the embodiment of the present invention is described in detail.

[0037] A volute processing process according to an embodiment of the present invention comprises the following steps:

[0038] Step 1, demoulding and parting: In the modeling software, first split the nozzle of the volute model to form a separate nozzle model, and then extract the flow channel surface of the remaining volute model, such as Figure 1 As shown, find the center line of the undercut of the flow channel surface, and split the remaining volute model into two halves using the plane where the center line is located as the dividing plane, thereby forming a first shell model and a second shell model, as shown in Figure 2 shown.

[0039] When the volute model is placed along the vertical direction with its axis extending, the first shell model is the upper shell model, and the second shell model is the lower shell model. Figure 2 shown.

[0040] Step 2: adopt the following steps, namely adopt steps 21 to 24, to process the first shell according to the first shell model, and to process the second shell according to the second shell model.

[0041] Step 21: Firstly, a blank single piece of the first shell and a blank single piece of the second shell are processed.

[0042] Step 22: Machine at least two locating pin holes on the blank. Figure 3 .

[0043] Step 23: Rough-process the blank to remove the machining allowance and mill out the right-angle edge, which will be used as the angular alignment reference in the subsequent process. After leaving 1-3mm, perform overall stress relief. Perform overall stress relief on the blank, that is, heat the blank at a temperature less than or equal to 150°C. Overall stress relief can avoid stress concentration on the blank after a large amount of machining allowance is removed during rough processing.

[0044] Step 24: Mill out the base surface, use the base surface for positioning, perform semi-finishing milling, and then perform finishing.

[0045] It should be noted that in step 2, the first shell and the second shell are processed separately. For example, the first shell is processed by steps 21 to 24 first, and then the second shell is processed by steps 21 to 24.

[0046] In this embodiment, in step 23, the right-angle edges are milled out, and after the flow rate reaches 2 mm, overall stress relief is performed.

[0047] Step 3: Process the nozzle according to the nozzle model, process the stopper on the side where the nozzle is connected to the flow channel, and process the weld on the side of the nozzle away from the flow channel;

[0048] Step 4: Component Processing:

[0049] Step 41: Using the positioning pin hole as a positioning point, snap the first shell and the second shell together, and fix the first shell and the second shell with bolts;

[0050] Step 42: Fix the first shell and the second shell by spot welding, and then remove welding stress;

[0051] Step 43: Using the stopper as a positioning point, connect the pipe port and the welded first shell and second shell, and then weld the pipe port;

[0052] Step 5: Leak detection.

[0053] The model software uses three-dimensional model software, such as UG / NX. In the model software, the volute model excluding the nozzle is divided into two halves according to the plane where the center line of the undercut of the flow channel surface is located, so that the flow channel is divided into two halves, and each half of the volute model corresponds to one half of the flow channel. It should be noted that the half of the flow channel here does not specifically refer to one half of the flow channel, the same below. The two halves of the volute model are buckled together to form a complete flow channel, so that for the first shell model and the second shell model after the separation, the half of the flow channel located thereon is visible, open, and not covered as a whole. In other words, the flow channel part on the first shell model and the second shell model is equivalent to a groove opened on the surface, thereby providing conditions for the tool of the processing machine tool to directly point to the flow channel, providing a larger space for the movement of the tool, so that the first shell model and the second shell model can use a processing machine tool, thereby facilitating the subsequent processing of the half flow channel on the first shell model and the second shell model, and providing favorable conditions for ensuring the processing accuracy of the flow channel.

[0054] In the related art, the volute needs to be connected to the pipeline when in use, so it is necessary to process a weld on the outside of the pipe mouth of the volute (that is, the side of the pipe mouth away from the upper flow channel) for welding with the pipeline. The volute processing technology of the embodiment of the present invention splits the pipe mouth model into separate sub-components in the model software, and processes them separately. This can avoid processing welds connected to the pipeline on the first shell and the second shell, and also avoid volute leakage caused by misalignment or deviation of the weld when the first shell and the second shell are buckled and fixed, thereby reducing the difficulty of processing the weld, thereby reducing the difficulty of processing the volute.

[0055] When processing the blank single piece of the first shell and the blank single piece of the second shell, positioning pin holes are processed on the single pieces, and the first shell and the second shell can be fastened with the positioning pin holes as positioning points, thereby ensuring the fastening accuracy of the two half-flow channels, avoiding misalignment of the inner wall of the flow channel, and ensuring the contour of the flow channel.

[0056] The right-angled edge processed in step 23 can provide a reference for angular alignment in subsequent processes to ensure the processing accuracy of the runner and the single piece. The base surface first processed in step 24 can be positioned for the semi-finishing milling process to ensure the processing accuracy of the runner and the single piece. The runner adopts a step-by-step processing method of rough machining, semi-finishing milling and finishing, which can ensure the roughness and contour accuracy of the runner machining, avoid rework, and have high processing efficiency.

[0057] Therefore, the volute processing technology of the embodiment of the present invention splits the volute model from the overall workpiece into three sub-parts, namely the nozzle model, the first shell model and the second shell model, so that the flow channel is exposed as a whole, and the sub-parts are processed separately, which not only reduces the processing difficulty of the flow channel, but also improves the processing accuracy of the flow channel, ensures the roughness and contour of the flow channel, improves the processing efficiency of the volute, and reduces the processing difficulty and cost of the volute.

[0058] In some embodiments, in step 1, in the model software, a shadow curve command is used to find the center line of the undercut of the flow channel surface, the center line is optimized, the optimized center line is stretched into a sheet body using a stretch command, and the volute model is split into two halves using a split body select face command.

[0059] In some embodiments, in step 1, after the volute model is split into two halves, the two halves of the volute model are split by establishing a reference plane, or the two halves of the volute model are split by forming a sheet body through a stretching command, and after the splitting, the multiple split first shells are merged into a first shell model through a merge command, and the multiple split second shells are formed into a second shell model. By splitting and optimizing the first shell model and the second shell model multiple times, the undercut part of the flow channel on the first shell model and the second shell model can be further reduced, which is more conducive to processing the flow channel.

[0060] In some embodiments, in step 21, according to the dimension data of the first shell model or the second shell model, the minimum range of the first shell blank or the second shell blank is calculated through theoretical modeling, and a processing allowance of 20-30 mm is added to process the first shell blank single piece or the second shell blank single piece, and then the clamping position structure and process reinforcement ribs are processed on the blank single piece, such as Figure 3 and Figure 4 In step 22 and step 23, the clamping structure is matched with the processing machine tool to clamp the single piece. After step 24, the process reinforcement ribs on the blank single piece are removed, thereby completing the processing of the first shell or the second shell.

[0061] The processing of the clamping structure can facilitate the installation of the blank single piece on the processing machine tool, and the processing of the process reinforcement ribs can provide a connection point between the processed first shell / second shell and the process clasp (the process clasp is the edge part of the blank single piece), thereby ensuring that during subsequent processing, the first shell / second shell is positioned and installed on the processing machine tool through the process clasp, thereby further facilitating the processing of the first shell and the second shell, which is conducive to further reducing the processing difficulty of the flow channel, further improving the roughness and contour accuracy of the flow channel, and further improving the processing efficiency of the volute.

[0062] Specifically, the additional machining allowance of the blank is 20mm, 25mm or 30mm, wherein the reference surface, the profile line and the clamping position structure all require additional machining allowance to facilitate subsequent processing. In the volute processing technology of the embodiment of the present invention, the additional machining allowance of the blank is 25mm.

[0063] Specifically, in the volute processing technology of the embodiment of the present invention, the number of positioning pin holes processed in step 22 is two.

[0064] In some embodiments, in step 22 and step 23, as Figure 5 As shown in the figure, for the processing of the flow channel surface, the flow channel profile is first extracted in the model software, and points are generated on the profile with a point spacing of 0.04-0.06mm. The points are sorted into a processing program of the processing machine tool, and the flow channel surface is processed using the processing program. In this way, the accuracy of the profile can be guaranteed, and then the accuracy of the flow channel surface can be guaranteed.

[0065] Specifically, the points on the profile of the embodiment of the present invention are spaced 0.05 mm apart.

[0066] In some embodiments, in step 23, during rough machining, the machining machine tool uses a cycle instruction to quickly remove the excess and achieve preliminary machining, thereby saving machining time and further improving the machining efficiency of the volute. In step 24, the machining machine tool uses a linear interpolation instruction for fine machining and adds tool radius compensation, which is conducive to ensuring the machining accuracy of the profile and then ensuring the accuracy of the flow path surface.

[0067] In some embodiments, in step 23 and step 24, during rough machining and semi-finishing milling, a large diameter tungsten steel tool is used, which can adapt to the volute made of aluminum alloy and ensure the roughness and contour of the flow channel during rough machining.

[0068] In step 24, when semi-finishing the flow channel surface, a reserve of 0.15-0.25 mm is left, and then fine machining is performed. In this embodiment, when semi-finishing the flow channel, a reserve of 0.2 mm is left.

[0069] In step 24, a diamond turning blade is used for finishing, so that the surface of the profile processed in this way is smooth and has good roughness, and then the roughness and contour of the flow channel surface are good.

[0070] In step 24, after fine machining, a small ball cutter is used to clean the undercut surface and the volute tongue surface in the flow channel, which can remove the undercut surface and the volute tongue surface left by the previous machining, thereby further improving the accuracy of the flow channel.

[0071] In some embodiments, in step 41, Figure 6 As shown, before the first shell and the second shell are fastened together, welding grooves are first processed on the first shell and the second shell respectively. In step 43, when welding the pipe mouth, it is necessary to process welding grooves on the pipe mouth and the fixed first shell and the second shell. The angle of the groove surface is 30°-60°, and the thickness of the groove edge is greater than or equal to 2mm. In this way, when welding the first shell and the second shell, it is avoided that welding penetration causes a weld nodule to be formed on the wall surface of the flow channel, thereby further ensuring the contour and accuracy of the flow channel.

[0072] In this embodiment, the angle of the groove surface of the welding groove is 45°, and the thickness of the groove edge is 2 mm.

[0073] In step 41 , the tightening force of the bolts fixing the first shell and the second shell is less than or equal to 6 Nm, so as to avoid welding collapse caused by a large tightening force.

[0074] In some embodiments, in step 42 and step 43, before welding, the parts are preheated to a temperature less than or equal to 150°C, and tungsten inert gas shielded arc welding is used. After welding is completed, welding stress caused by weld shrinkage is removed.

[0075] In step 5, the volute is sealed with an airtight tool. The airtight tool uses a cover plate and a sealing ring to perform an airtight test on the part. Gas is injected into the flow channel to form an internal pressure of 6 kPa. The leakage is determined by observing whether the pressure gauge data connected to the flow channel decreases. Then the sealed volute is placed in water to observe whether bubbles are generated.

[0076] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0077] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0078] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0079] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0080] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0081] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A volute processing technology, characterized in that: The following steps are involved: Step 1, demolding and parting: in the model software, firstly, the nozzle of the volute model is separated to form a separate nozzle model, then the flow channel surface of the flow channel of the remaining volute model is extracted, the center line of the undercut of the flow channel surface is found, and the remaining volute model is split into two halves with the plane where the center line is located as the dividing plane, thereby forming a first shell model and a second shell model; Step 2, using the following steps to process the first shell according to the first shell model, and to process the second shell according to the second shell model: Step 21: firstly process a single blank piece of the first shell body and / or a single blank piece of the second shell body; Step 22: machining at least two positioning pin holes on the blank; Step 23: Rough machining the blank to remove machining allowance, mill out right-angle edges, leave 1-3 mm, and then perform overall stress relief; Step 24: Mill out the base surface, use the base surface for positioning, perform semi-finishing milling, and then perform finishing; Step 3: Processing the nozzle according to the nozzle model, processing a stopper on the side of the nozzle connected to the flow channel, and processing a weld on the side of the nozzle away from the flow channel; Step 4: Component Processing: Step 41: Using the positioning pin hole as a positioning point, buckle the first shell and the second shell, and fix the first shell and the second shell with bolts; Step 42: Fix the first shell and the second shell by spot welding, and then remove welding stress; Step 43: Using the stopper as a positioning point, connect the pipe port and the welded first shell and second shell, and then weld the pipe port; Step 5: Leak detection.

2. The volute processing technology according to claim 1, characterized in that: In step 1, in the model software, the shadow curve command is used to find the undercut center line of the flow path surface, the center line is optimized, the optimized center line is stretched into a sheet body by the stretch command, and the volute model is split into two halves by the split body selection face command.

3. The volute processing technology according to claim 2, characterized in that: In step 1, after the volute model is split into two halves, the two halves of the volute model are split by establishing a reference plane, or the stretching command is used to form a sheet body for splitting. After the splitting, the multiple split first shell parts are combined into a first shell model through a merge command, and the multiple split second shells are formed into a second shell model.

4. The volute processing technology according to claim 1, characterized in that: In step 21, according to the dimension data of the first shell model or the second shell model, the minimum range of the blank of the first shell or the second shell is calculated through theoretical modeling, and a processing allowance of 20-30 mm is added to process the blank single piece of the first shell or the second shell, and then the clamping position structure and process reinforcement ribs are processed on the blank single piece; in steps 22 and 23, the clamping position structure is matched with the processing machine tool to clamp the single piece; after step 24, the process reinforcement ribs on the blank single piece are cut off, thereby completing the processing of the first shell or the second shell.

5. The volute processing technology according to claim 1, characterized in that: In step 22 and step 23, for the processing of the flow channel surface, the corresponding contour line of the flow channel on the first shell model or the second shell model is first extracted in the model software, points are generated on the contour line, and the interval between adjacent points is 0.04-0.06mm. The points are arranged into a processing program of a processing machine tool, and the flow channel surface is processed using the processing program.

6. The volute processing technology according to claim 1, characterized in that: In step 23, during rough machining, the machining machine tool uses cycle instructions for machining; and / or, in step 24, the machining machine tool uses linear interpolation instructions for finishing machining and adds tool radius compensation.

7. The volute processing technology according to claim 1, characterized in that: In step 23 and step 24, a large diameter tungsten steel tool is used for rough machining and semi-finishing milling; in step 24, when semi-finishing the flow channel surface, a 0.15-0.25 mm allowance is left before finishing; and / or, in step 24, a diamond turning insert is used for finishing.

8. The volute processing technology according to claim 1, characterized in that: In step 24, after finishing, a small ball cutter is used to clean the undercut surface and the volute tongue surface in the flow channel.

9. The volute processing technology according to claim 1, characterized in that: In step 41, before the first shell and the second shell are fastened together, welding grooves are first processed on the first shell and the second shell respectively. In step 43, when welding the pipe mouth, it is necessary to process welding grooves on the pipe mouth and the first shell and the second shell after fixation. The angle of the groove surface is 30°-60°, and the thickness of the groove edge is greater than or equal to 2mm; and / or, in steps 42 and 43, before welding, the parts are preheated, and the preheating temperature is less than or equal to 150°C.

10. The volute processing technology according to claim 1, characterized in that: In step 41, the tightening force of the bolts fixing the first shell and the second shell is less than or equal to 6Nm; and / or, in steps 42 and 43, tungsten inert gas shielded arc welding is adopted, and the welding stress caused by weld shrinkage is removed after welding is completed.

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