A uniform abrasive flow finishing method for a large aspect ratio rectangular cross-section channel

Abstract

The application discloses a large-length-width-ratio rectangular equal-section channel uniformity abrasive flow finishing method, which comprises the following steps: step 1, before abrasive flow finishing, according to the material removal rate distribution law of the large-length-width-ratio rectangular equal-section channel in abrasive flow finishing, the channel is divided into left, middle and right three rectangular to-be-processed areas along the long side of the cross section; step 2, a profiling solid core is designed and manufactured for the middle to-be-processed area of the channel; step 3, the whole channel is processed by using abrasive flow finishing until the surface roughness of the blade meets the design requirement; and step 4, the profiling solid core is assembled with the middle to-be-processed area of the channel, then the left and right two rectangular to-be-processed areas are processed by using abrasive flow finishing until the surface roughness of the left and right two to-be-processed areas meets the design requirement. The machining uniformity of the whole channel is reliably ensured.

Description

Technical Field

[0001] This invention belongs to the field of abrasive finishing technology, specifically relating to a method for abrasive finishing of a rectangular equal-section channel with a large aspect ratio. Background Technology

[0002] Abrasive flow finishing is a special machining technique that improves the surface quality of a workpiece by honing it using extruded viscoelastic fluid abrasives. Although abrasive flow finishing offers good accessibility and high surface quality, it suffers from uneven processing when used for machining rectangular channels with large aspect ratios. Specifically, the finishing efficiency of the short side of the channel cross-section is much lower than that of the long side, which limits the application of this technique in rectangular channels with large aspect ratios.

[0003] To improve the uniformity of abrasive flow finishing in variable cross-section channels, existing technologies involve adding a contoured mold core within the channel. A uniform gap flow channel is constructed between the mold core's outer surface and the channel, allowing the abrasive fluid to flow at similar velocities, thus improving the overall processing uniformity. However, this method is not suitable for rectangular channels with large aspect ratios and uniform cross-sections. This is because if the mold core is too thin, its rigidity may not meet requirements; conversely, increasing the core thickness reduces the channel gap, resulting in excessive abrasive flow resistance and consequently, low or no processing efficiency in abrasive flow finishing. Therefore, achieving uniformity in abrasive flow finishing for rectangular channels with large aspect ratios is a critical technical challenge that urgently needs to be overcome. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a method for uniform abrasive flow finishing of rectangular channels with large aspect ratios. Before abrasive flow finishing, the channel is divided into three rectangular processing areas (left, middle, and right) along the long side of the cross-section according to the material removal rate distribution law in abrasive flow finishing. Then, a solid mold core is designed and manufactured for the middle processing area of ​​the channel. The entire channel is then processed using abrasive flow finishing until the surface roughness of the blades meets the design requirements. Finally, the mold core is assembled with the middle processing area of ​​the channel, and the left and right rectangular processing areas are then processed using abrasive flow finishing until the surface roughness of the left and right processing areas meets the design requirements. At this point, the surface roughness of the entire channel meets the design requirements and has high uniformity.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for machining uniform abrasive flow channels with a large aspect ratio and rectangular equal cross-section includes:

[0007] Step 1: Before abrasive finishing, based on the material removal rate distribution law of the large aspect ratio rectangular equal cross-section channel in abrasive finishing, divide the channel into three rectangular processing areas along the long side of the cross-section: left, middle, and right.

[0008] Step 2: Design and manufacture a contour-following solid mold core for the area to be processed in the middle of the channel;

[0009] Step 3: Use abrasive flow finishing to process the entire channel until the surface roughness of the blade meets the design requirements;

[0010] Step 4: Assemble the solid mold core with the area to be processed in the middle of the channel, and then use abrasive flow finishing to process the two rectangular areas to be processed on the left and right until the surface roughness of the two areas to be processed meets the design requirements.

[0011] To optimize the above technical solution, the specific measures also include:

[0012] The aforementioned rectangular equal-section channels with large aspect ratios are manufactured using electrical discharge machining, wire electrical discharge machining, additive manufacturing, or casting, and their aspect ratio is at least greater than 5.

[0013] In step 1 above, before abrasive finishing, the material removal rate distribution in abrasive finishing is obtained through theoretical analysis or pre-test of abrasive finishing.

[0014] The division of the processing area in step 1 above follows the following principles:

[0015] The long side of the rectangular cross-section of the left and right processing areas coincides with the short side of the rectangular cross-section of the channel. The short side of the rectangular cross-section of the left and right processing areas is collinear with the long side of the rectangular cross-section of the channel. The aspect ratio of the rectangular cross-section of the left and right processing areas is not less than 2.

[0016] In step 2 above, the distance between the upper edge of the rectangular cross-section of the solid mold core and the upper edge of the rectangular cross-section of the channel is not less than 5 times the maximum diameter of the hard abrasive grains in the fluid abrasive used for abrasive finishing, and is not greater than the width of the rectangular cross-section of the left and right processing areas.

[0017] The mold core materials mentioned above are hardened steel and nylon, and the surface roughness Ra of the mold core is <1.6μm.

[0018] The abrasive finishing process described in step 3 above can be performed using unidirectional or bidirectional abrasive finishing.

[0019] The fluid abrasive used is a viscoelastic solid-liquid two-phase fluid abrasive;

[0020] When using unidirectional abrasive finishing, the mold core is designed with a cone angle of 1 to 5° in the length direction, and in the assembled state, the vector direction of the mold core from the center of the small end face to the center of the large end face is the same as the flow direction of the fluid abrasive.

[0021] In step 3 above, the abrasive flow finishing process involves adding a flow-guiding fixture with the same cross-sectional shape as the channel outside the channel inlet and outlet to control the rounding of the channel inlet and outlet edges during the abrasive flow finishing process.

[0022] In step 4 above, the assembled mold core is equidistant from the upper and lower surfaces of the channel, and the assembled mold core is equidistant from the left and right surfaces of the channel.

[0023] The present invention has the following beneficial effects:

[0024] Before abrasive finishing, the method of this invention divides the channel into three processing areas (left, middle, and right) along the cross-sectional direction according to the material removal rate distribution law in abrasive finishing. A contoured solid mold core is designed for the middle processing area of ​​the channel. The entire processing process is divided into two stages. The first stage is to assemble the mold core with the middle processing area of ​​the channel, and then use abrasive finishing to process the left and right processing areas until the surface roughness of the left and right processing areas meets the processing requirements. The second stage is to disassemble the mold core and then use abrasive finishing to process the entire channel until the surface roughness of the blades meets the processing requirements, thereby achieving high uniformity abrasive finishing of the entire channel.

[0025] The method of this invention is particularly suitable for rectangular cross-section channels with large aspect ratios. The greater the aspect ratio of the channel or the narrower the channel width, the more prominent the advantages of this method become. Therefore, it can solve the problem of abrasive finishing that cannot be solved by existing technical solutions.

[0026] The method of this invention does not require the use of flow field simulation or other methods to design the shape and size of the mold core. The processing sequence of processing the middle area to be processed first, followed by the left and right areas to be processed, can achieve interference-free localized processing of the three areas to be processed, reliably ensuring the processing uniformity of the entire channel. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a rectangular equal-section channel structure with a large aspect ratio in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the processing area division of a rectangular equal-section channel with a large aspect ratio in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the mold core structure in an embodiment of the present invention;

[0030] Figure 4This is a schematic diagram of the assembly of the mold core and the area to be processed in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the non-mold core abrasive finishing process in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the finishing process of adding mold core abrasive particles in an embodiment of the present invention;

[0033] The markings in the diagram are: 1-workpiece, 2-rectangular equal-section channel with large aspect ratio, 3-left area to be processed, 4-middle area to be processed, 5-right area to be processed, 6-fluid abrasive, 7-flow guide fixture for smooth finishing without mold core, 8-flow guide fixture for smooth finishing with mold core. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] Although the steps in this invention are arranged by reference numerals, this is not intended to limit the order of the steps. Unless the order of the steps is explicitly stated or the execution of a step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" as used herein refers to and covers any and all possible combinations of one or more of the associated listed items.

[0036] A method for machining uniform abrasive flow channels with a large aspect ratio and rectangular equal cross-section includes:

[0037] Step 1: Before abrasive finishing, based on the material removal rate distribution law of the large aspect ratio rectangular equal cross-section channel in abrasive finishing, divide the channel into three rectangular processing areas along the long side of the cross-section: left, middle, and right.

[0038] Step 2: Design and manufacture a contour-following solid mold core for the area to be processed in the middle of the channel;

[0039] Step 3: Use abrasive flow finishing to process the entire channel until the surface roughness of the blade meets the design requirements;

[0040] Step 4: Assemble the solid mold core with the area to be processed in the middle of the channel, and then use abrasive flow finishing to process the two rectangular areas to be processed on the left and right until the surface roughness of the two areas to be processed meets the design requirements.

[0041] In the embodiments, the rectangular equal-section channel with a large aspect ratio is manufactured by electrical discharge machining, wire electrical discharge machining, additive manufacturing, or casting, and its aspect ratio is at least greater than 5.

[0042] In step 1, before abrasive finishing, the material removal rate distribution of the variable cross-section deep and narrow inner cavity in abrasive finishing is obtained through theoretical analysis or abrasive finishing pre-test.

[0043] The division of the processing area in step 1 follows these principles:

[0044] The long side of the rectangular cross-section of the left and right processing areas coincides with the short side of the rectangular cross-section of the channel. The short side of the rectangular cross-section of the left and right processing areas is collinear with the long side of the rectangular cross-section of the channel. The aspect ratio of the rectangular cross-section of the left and right processing areas is not less than 2.

[0045] In step 2, the distance between the upper edge of the rectangular cross-section of the solid mold core and the upper edge of the rectangular cross-section of the channel is not less than 5 times the maximum diameter of the hard abrasive grains in the fluid abrasive used for abrasive finishing, and is not greater than the width of the rectangular cross-section of the left and right processing areas.

[0046] The mold core material is made of hardened steel and nylon, and the surface roughness R of the mold core is... a <1.6μm.

[0047] The abrasive finishing process described in step 3 can be performed using unidirectional or bidirectional abrasive finishing.

[0048] The fluid abrasive used is a viscoelastic solid-liquid two-phase fluid abrasive;

[0049] When using unidirectional abrasive finishing, the mold core is designed with a cone angle of 1 to 5° in the length direction, and in the assembled state, the vector direction of the mold core from the center of the small end face to the center of the large end face is the same as the flow direction of the fluid abrasive.

[0050] In step 3, the abrasive finishing process involves adding flow-guiding fixtures with the same cross-sectional shape as the channel outside the channel inlet and outlet to control the rounding of the channel inlet and outlet edges during the abrasive finishing process.

[0051] The assembly described in step 4 requires ensuring that the distance between the assembled mold core and the upper and lower surfaces of the channel is equal, and that the distance between the assembled mold core and the left and right surfaces of the channel is equal.

[0052] Example 1

[0053] like Figure 1As shown, a workpiece 1 is a 304 stainless steel cylinder with a rectangular equal-section channel 2 with a large aspect ratio. The dimensions of the rectangular equal-section channel 2 are (length × width × depth) 60mm × 10mm × 150mm. After the rectangular equal-section channel 2 is machined by wire electrical discharge machining, the surface roughness R is... a 2.0μm, design requirement is R a For surfaces smaller than 0.6 μm, abrasive finishing is required to reduce surface roughness. The abrasive finishing efficiency for the short side of the cross-section of such channels is much lower than that for the long side, resulting in poorer processing uniformity.

[0054] To improve the uniformity of abrasive finishing of the rectangular equal-section channel 2 with a large aspect ratio, the following technical solution is adopted according to the method of the present invention:

[0055] First, the rectangular channel 2 with a large aspect ratio and uniform cross-section is divided into three rectangular areas to be processed along the long side of the cross-section: left, middle, and right. Figure 2 As shown in the figure. The cross-sectional length and width of the left processing area 3 and the right processing area 5 are 10mm and 5mm respectively, and the cross-sectional length and width of the middle processing area 4 are 50mm and 10mm respectively.

[0056] Secondly, the design is as follows Figure 3 The solid mold core shown is made of hardened steel and measures 50mm × 9.8mm × 150mm. Its height is slightly less than the width of the channel cross-section. The positional relationship between the mold core and the area to be processed after assembly is as follows: Figure 4 As shown.

[0057] Then, the stainless steel coreless abrasive finishing fixture 7 is assembled with the workpiece, with an assembly gap of 2mm, and the entire channel is finished using bidirectional abrasive finishing. Figure 5 As shown, until the surface roughness of the intermediate area to be processed is lower than R. a 0.6μm. During this processing, the fluid abrasive 6 enters through the entire channel, using the entire channel as the processing surface. The finishing efficiency is highest in the middle area to be processed, and the finishing efficiency decreases as you get closer to the left and right sides of the area to be processed.

[0058] Then, the fluid abrasive in the channel is cleaned, and the coreless abrasive finishing guide jig 7 is replaced with a stainless steel cored abrasive finishing guide jig 8. The core is then assembled with the area to be processed in the middle of the channel, and the two rectangular areas to be processed on the left and right are then finished using bidirectional abrasive finishing. Figure 6 As shown. During this processing, the fluid abrasive 6 can only flow through the left and right processing areas, thus the left and right processing areas are the processing areas, while no material removal occurs in the middle processing area. As the surface roughness of the left and right processing areas decreases, the surface roughness value of the entire channel tends to be consistent, eventually meeting the design requirements.

[0059] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0060] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for machining uniform abrasive flow lines through rectangular channels with large aspect ratio and uniform cross-section, characterized in that, include: Step 1: Before abrasive finishing, based on the material removal rate distribution law of the large aspect ratio rectangular cross-section channel in abrasive finishing, the channel is divided into three rectangular processing areas along the long side of the cross-section: left, middle, and right. The division of the processing areas follows the following principles: the long side of the rectangular cross-section of the left and right processing areas coincides with the short side of the rectangular cross-section of the channel; the short side of the rectangular cross-section of the left and right processing areas is collinear with the long side of the rectangular cross-section of the channel; and the aspect ratio of the rectangular cross-section of the left and right processing areas is not less than 2. Step 2: Design and manufacture a contour solid mold core for the area to be processed in the middle of the channel; wherein the distance between the upper edge of the rectangular cross-section of the contour solid mold core and the upper edge of the rectangular cross-section of the channel is not less than 5 times the maximum diameter of the hard abrasive grains in the fluid abrasive used for abrasive finishing, and not greater than the width of the rectangular cross-section of the left and right areas to be processed. Step 3: Use abrasive flow finishing to process the entire channel until the surface roughness of the blade meets the design requirements; Step 4: Assemble the solid mold core with the area to be processed in the middle of the channel, and then use abrasive flow finishing to process the two rectangular areas to be processed on the left and right until the surface roughness of the two areas to be processed meets the design requirements.

2. The method for uniform abrasive finishing of a rectangular channel with a large aspect ratio and uniform cross-section according to claim 1, characterized in that, The rectangular equal-section channel with a large aspect ratio is manufactured by electrical discharge machining, wire electrical discharge machining, additive manufacturing, or casting, and its aspect ratio is at least greater than 5.

3. The method for uniform abrasive finishing of a rectangular channel with a large aspect ratio and uniform cross-section according to claim 1, characterized in that, In step 1, before abrasive finishing, the material removal rate distribution in abrasive finishing is obtained through theoretical analysis or pre-tests of abrasive finishing.

4. The method for uniform abrasive finishing of a rectangular channel with large aspect ratio and uniform cross-section according to claim 1, characterized in that, The mold core material is made of quenched steel and nylon, and the surface roughness Ra of the mold core is less than 1.6 μm.

5. The method for uniform abrasive finishing of a rectangular channel with a large aspect ratio and uniform cross-section according to claim 1, characterized in that, The abrasive finishing process described in step 3 can be performed using unidirectional or bidirectional abrasive finishing. The fluid abrasive used is a viscoelastic solid-liquid two-phase fluid abrasive; When using unidirectional abrasive finishing, the mold core is designed with a cone angle of 1~5° in the length direction, and in the assembled state, the vector direction of the mold core from the center of the small end face to the center of the large end face is the same as the flow direction of the fluid abrasive.

6. The method for uniform abrasive finishing of a rectangular channel with large aspect ratio and uniform cross-section according to claim 1, characterized in that, In step 3, the abrasive finishing process involves adding flow-guiding fixtures with the same cross-sectional shape as the channel outside the channel inlet and outlet to control the rounding of the channel inlet and outlet edges during the abrasive finishing process.

7. The method for uniform abrasive finishing of a rectangular channel with large aspect ratio and uniform cross-section according to claim 1, characterized in that, In step 4, the assembled mold core is equidistant from the upper and lower surfaces of the channel, and the assembled mold core is equidistant from the left and right surfaces of the channel.

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