Method for forming small size thin wall pleated filter for hydraulic systems

Abstract

The application discloses a forming method of a small-size thin-wall pleated filter screen for a hydraulic system, and comprises the following steps: a micro-hole surface structure with a large depth-diameter ratio is processed on an original plate through an electron beam cutting method to form a micro-hole surface plate; the size of each part of the unfolded surface of the pleated filter screen model is fitted by unfolding the surface of the pleated filter screen model, then the micro-hole surface plate is punched / spun and shaped by a punching / spinning machine tool to process a curved screen, and the end of the curved screen is cut at the same time; the curved screen is punched / rolled and shaped by a punching / rolling machine tool to process a pleated curved screen, and the end of the pleated curved screen is cut at the same time. The forming method is efficient and convenient, has high machining precision, can be combined with multiple forming methods, and the micro-hole of the pleated filter screen processed by the method does not have a crack defect, and the forming method is especially suitable for machining of small-size and high-complexity parts.

Description

Technical Field

[0001] This invention belongs to the technical field of hydraulic system component processing methods, specifically relating to a forming method for small-sized thin-walled pleated filter screens for hydraulic systems. Background Technology

[0002] In a machine's hydraulic system, components such as orifices, safety valves, and other sensitive parts are resistant to small particulate contaminants. However, large particulate contaminants can cause these components to fail, leading to catastrophic consequences. During operation, filters maintain the cleanliness of the main channels in a machine's hydraulic system. Large particulate contaminants introduced after a period of operation require protection from pleated filters. These pleated filters are typically located upstream of or integrated with critical components such as check valves, throttle valves, and safety valves. If these filters malfunction, it can quickly lead to failure and potentially even more serious risks.

[0003] The machine's hydraulic system is extremely complex, involving many different types of components. Because the shapes of the components using pleated filters vary, the required pleated filters for each component must be adjusted according to the component's shape. While some components have relatively regular structures, a large number still require pleated filters with complex curved surfaces. Furthermore, due to the small size of these components, many on the millimeter scale and with an overall structure less than one centimeter, molding these tiny components with microchannels and complex curved surfaces is extremely difficult. For example, for curved pleated filters only a few millimeters long, the short length and complex shape of the pleated surfaces make molding difficult. Forming micropores on the pleated surfaces also presents challenges, especially maintaining the shape of regular circular through-holes at the root of the pleats. Based on this, Chinese Patent No. CN113843586B, published on December 28, 2021, discloses a combined processing method for complex curved surface wrinkled filter screens for aircraft hydraulic systems. This method is particularly suitable for processing small-sized, highly complex parts. However, this processing method is too simple and does not take into account the problem of tearing defects that easily occur when the perforated mesh plate is drawn into spherical parts.

[0004] Electron beam cutting technology uses the energy of an electron beam to melt the material being cut, forming a cut through evaporation or gravity flow of the melt. This technology can typically achieve the machining of micro-holes with large aspect ratios. Its advantages include high power density, minimal workpiece deformation, high precision, and virtually no material selectivity. Currently, electron beam cutting technology is mainly used in semiconductor manufacturing, micro-motor systems, nano-motor systems, and microscopy, but its application in the machining of complex curved surface micro-components has not yet been reported. Summary of the Invention

[0005] The purpose of this invention is to provide a method for forming small-sized thin-walled pleated filters for hydraulic systems, wherein the micropores of the pleated filter processed by this method will not exhibit tearing defects.

[0006] The technical solution adopted in this invention is a method for forming small-sized thin-walled pleated filter screens for hydraulic systems, specifically implemented according to the following steps:

[0007] S1. Using electron beam cutting, a surface structure with a large aspect ratio of micro-perforated holes is processed on the original plate to form a surface micro-perforated plate.

[0008] S2. By unfolding the pleated surface of the pleated filter model, the dimensions of each part of the unfolded curved surface are fitted. Then, the micro-perforated plate obtained in step S1 is stamped / spun into a curved screen by a stamping / spinning machine, and the ends of the curved screen are cut at the same time.

[0009] S3. The curved screen obtained in step S2 is stamped / rolled and shaped using a stamping / rolling machine to produce a pleated curved screen, and the ends of the pleated curved screen are cut at the same time.

[0010] The invention is further characterized by:

[0011] Step S1 is as follows:

[0012] S11. Fix the original sheet material onto the electron beam processing platform;

[0013] S12. Import the micro-hole pattern to be processed into the equipment and set the electron beam processing parameters;

[0014] S13. Start the electron beam processing platform and process the surface structure of the large depth-to-diameter ratio micro-hole according to the set processing trajectory to form a surface micro-hole plate.

[0015] S14. Processing completed. Remove the surface micro-perforated plate.

[0016] Step S2 is as follows:

[0017] S21. Determine the dimensions of each part of the curved surface after the pleated filter model is unfolded, and make the deep drawing deformation die LS01 for stamping / spinning according to the dimensions;

[0018] S22. Cutting and blanking: Place the micro-perforated flat plate obtained in step S1 into the processing position of the stamping / spinning machine. According to the dimensions obtained in step S21, use the cutting die to cut and blank the material to obtain a circular flat plate blank.

[0019] S23. One-time deformation: Keep the processing position of the circular flat blank unchanged, set the stamping / spinning process parameters, and use the deep drawing deformation die LS01 to stamp / spin deform the circular flat blank. The stamping / spinning depth is greater than the total height of the pleated filter screen after unfolding. After stamping / spinning, a curved screen is obtained.

[0020] Step S21 is as follows:

[0021] Unfold the pleated surface of the pleated filter model, and set the center of the circle on the opening side of the filter model as the zero point. This zero point is H mm away from the center point of the head. Then, starting from the zero point plane, measure the unfolded length of the corresponding filter pleat every h mm. This length is the circumference of the plane circle corresponding to the curved screen to be processed in step S2. From this, the radius of the plane circle corresponding to the curved screen can be obtained. The radius data is fitted with the corresponding distance from the top of the sphere to obtain a quadratic curve. Rotating this curve along the y-axis yields a simplified diagram of the curved screen. Based on this curve and the simplified diagram, the deep drawing deformation die LS01 is fabricated.

[0022] Step S3 is as follows:

[0023] S31. Secondary Deformation: Place the curved screen obtained in step S2 into the processing position of the stamping / rolling machine tool, set the stamping / rolling process parameters, use the deep drawing deformation die LS02 to stamp / roll the curved screen, control the wrinkle formation in the middle and bottom areas of the screen, and obtain the secondary deformed part after stamping / rolling.

[0024] S32. Initial Correction: Keeping the processing position of the secondary deformed part unchanged, the overall shape of the curved surface of the secondary deformed part is corrected by using a folding correction mold, including the initial folding correction, to obtain a quasi-finished part with folds.

[0025] S33. Secondary Shaping and Blanking: Keeping the processing position of the pre-finished part unchanged, a pleat-shaping-cutting composite mold is used to perform secondary shaping on the curved surface and pleats of the finished part, while cutting the bottom of the finished part to form a round flat end shell to obtain the finished part.

[0026] S34. Sample inspection: Inspect the shape and size of curved surfaces, wrinkled surfaces, and micropores on curved surfaces of finished parts.

[0027] During the deformation process in step S23 or step S31, surface appearance deformation occurs, but structural deformation does not occur.

[0028] The beneficial effects of this invention are:

[0029] This invention combines electron beam cutting technology with stamping / spinning / rolling processes. First, electron beam cutting technology is used to process a micro-hole array with a large aspect ratio on a sheet metal. Then, the pleated filter screen is processed in two stages: First, a stamping / spinning machine is used to process only the curved screen structure in the filter screen, without processing the pleats. Then, a stamping / rolling machine is used to process the pleats. During the two forming processes, only the curved surface deformation occurs, without structural deformation, so that the shape of the circular holes does not deform. This processing method can avoid tearing defects at the micro-holes of the filter screen, further ensuring the quality of the processed filter screen.

[0030] The forming method of this invention is efficient, convenient, and has high processing accuracy. It also offers a variety of forming methods that can be combined, making it particularly suitable for processing small-sized, highly complex parts. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the pleated filter screen processed according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the micropore array in the pleated filter screen processed according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram showing the unfolded pleated filter screen in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the deep drawing die LS01 used in Embodiment 1 of the present invention;

[0035] Figure 5 This is a schematic diagram of the deep drawing die LS02 used in Embodiment 1 of the present invention;

[0036] Figure 6 This is a schematic diagram of the spinning deformation die used in Embodiment 2 of the present invention;

[0037] Figure 7 This is a schematic diagram of the forming deformation mold used in Embodiment 2 of the present invention.

[0038] Among them, 1. screen body, 2. pleats, 3. micropores. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0040] This invention discloses a method for forming small-sized thin-walled pleated filter screens for hydraulic systems. First, an array of micro-holes is fabricated on a raw sheet material using electron beam cutting technology. Then, the sheet material with the micro-hole array is stamped / spun using a stamping / spinning machine to form a curved screen structure. Next, the ends of the curved screen are stamped / rolled using a stamping / rolling machine to form pleats. Finally, the ends of the curved screen are cut to form the pleated filter screen. This method is specifically implemented according to the following steps:

[0041] S1: Taking stainless steel plate as an example, the original plate is processed with electron beam cutting to create micro-holes with a large aspect ratio, thereby obtaining a micro-hole array on the surface of the stainless steel plate. Specifically:

[0042] S11: Fix the stainless steel plate onto the electron beam processing platform;

[0043] S12: Import the micro-hole pattern to be processed into the equipment and set the electron beam processing parameters;

[0044] S13: Start the electron beam processing platform and process the surface structure of the large aspect ratio micro-hole according to the set processing trajectory to form a surface micro-hole plate.

[0045] S14: Processing complete, remove the surface micro-perforated plate.

[0046] S2: By fitting the unfolded pleated surface, the dimensions of each part of the curved surface of the unfolded pleated filter screen are obtained. Then, the micro-perforated flat plate obtained in step S1 is stamped / spun into a curved screen using a stamping / spinning machine, i.e., a one-time deformation part. At the same time, the ends of the screen are cut. Specifically:

[0047] S21: Determine the unfolded dimensions of the pleated filter screen and fabricate the deep drawing die for stamping / spinning. LS01:

[0048] Unfold the pleated surface of the pleated filter model, and set the center of the circle on the opening side of the filter model as the zero point. This zero point is H mm away from the center point of the head. Then, starting from the zero point plane, measure the unfolded length of the corresponding filter pleat every h mm. This length is the circumference of the plane circle corresponding to the primary deformed part to be processed in step S2. From this, the radius of the plane circle corresponding to the primary deformed part can be obtained. The radius data is fitted with the corresponding distance from the dome to obtain a quadratic curve. Rotating this curve along the y-axis will yield a simplified diagram of the first-order deformed part. Based on this curve and the simplified diagram, the deep drawing deformation die LS01 is made.

[0049] S22: Cutting and blanking: Place the micro-perforated flat plate obtained in step S1 into the processing position of the stamping / spinning machine, and cut and blank the material using a cutting die according to the dimensions obtained in step S21 to obtain a circular flat plate blank.

[0050] S23: Primary Deformation: After cutting and blanking, keep the processing position of the circular flat blank unchanged, set the stamping / spinning process parameters, and use the deep drawing deformation die LS01 to stamp / spin deform the circular flat blank. The stamping / spinning depth is greater than Hmm to ensure that the subsequent forming is complete. During the screen forming process, the curved appearance deformation is generated, but the structural deformation is not generated. After the stamping / spinning is completed, a primary deformed part is obtained, namely the curved screen.

[0051] S3: The curved screen obtained in step S2 is micro-stamped / rolled using a stamping / rolling machine to create a pleated curved screen. Simultaneously, the ends of the screen are cut. Specifically:

[0052] S31: Secondary Deformation: Place the curved screen obtained in step S2 into the processing position of the stamping / rolling machine, set the stamping / rolling process parameters, and use the deep drawing deformation die LS02 to stamp / roll the curved screen. Control the wrinkling formation in the middle and bottom areas of the screen. During the wrinkling formation in the middle and bottom areas of the screen, the curved appearance deformation is generated, but the structural deformation is not generated. After the stamping / rolling is completed, a secondary deformed part is obtained.

[0053] S32: Initial Shaping: After two stages of deformation, the processing position of the secondary deformed part remains unchanged. The secondary deformed part is shaped using a folding shaping mold to correct the overall shape of the screen surface, including the initial folding shaping, to obtain a quasi-finished part with folds.

[0054] S33: Secondary Shaping and Blanking: After the initial shaping, keep the processing position of the pre-finished part fixed, use the pleated shaping-cutting composite mold to align the finished part for secondary shaping, perform final shaping of the screen surface and pleats, and cut the bottom of the finished part at the same time to form a round flat end shell to obtain the finished part.

[0055] S34: Sample inspection: Inspect the shape and size of the curved surface, wrinkled surface, and micropores on the curved surface of the finished part to see if they meet the size and accuracy requirements of the screen mesh for the curved surface with wrinkles.

[0056] Example 1:

[0057] The planar material used in this embodiment underwent the following treatment before being installed on the electron beam processing platform:

[0058] 1) Place the board in an ultrasonic cleaner and clean for 1-3 minutes;

[0059] 2) Remove the board, wipe off the surface moisture, and place it in a dryer. Dry it at 150-250℃ for 2-4 minutes.

[0060] 3) Once drying is complete, remove the boards and apply a protective film to the surface using a laminating machine. This lamination is to prevent scratches on the board surface; the protective film should be removed before use.

[0061] Figure 1 and Figure 2 This is a schematic diagram of the structure of the pleated filter screen processed in this embodiment. The screen body 1 with a circular curved surface has a ring of pleats 2 and micropores 3 are opened on the screen body 1, including the pleats 2.

[0062] The specific processing and forming steps of the filter screen in this embodiment are as follows:

[0063] S1: Micro-holes with large aspect ratios are fabricated on a processed planar plate using electron beam cutting, thereby creating a micro-hole array on the plate surface. Specifically:

[0064] S11: Clamp and fix the flat plate onto the electron beam processing platform;

[0065] S12: Import the micro-hole pattern to be processed into the equipment and set the electron beam processing parameters;

[0066] S13: Start the electron beam processing platform and process the surface structure of the large aspect ratio micro-hole according to the set processing trajectory to form a surface micro-hole plate.

[0067] S14: Processing complete, remove the surface micro-perforated plate.

[0068] S2: By fitting the unfolded pleated surface, the dimensions of each part of the curved surface of the unfolded pleated filter screen are obtained. Then, the micro-perforated flat plate obtained in step S1 is stamped and shaped using a stamping machine to form a curved screen, i.e., a one-time stamping deformation part. At the same time, the ends of the screen are cut. Specifically:

[0069] S21: Determine the unfolded dimensions of the pleated filter screen and fabricate the deep drawing die for stamping. LS01:

[0070] like Figure 3 As shown, unfold the pleated surface of the pleated filter model, and set the center of the circle on the opening side of the filter model as the zero point. This zero point is H mm away from the center point of the head. Then, starting from the zero point plane, measure the unfolded length of the corresponding filter pleat every h mm. This length is the circumference of the plane circle corresponding to the stamped part to be processed in step S2. From this, the radius of the plane circle corresponding to the stamped part can be obtained. The radius data is fitted with the corresponding distance from the dome to obtain a quadratic curve. Rotating this curve along the y-axis will yield a simplified diagram of the stamping deformation part. Based on this curve and the simplified diagram, the deep drawing deformation die LS01 is made.

[0071] S22: Cutting and blanking: Place the sheet material obtained in step S1 into the processing position of the stamping machine, and cut and blank it according to the dimensions obtained in step S21 using a cutting die to obtain a round flat blank.

[0072] S23: Single-stage stamping deformation: After cutting and blanking, keeping the processing position of the circular flat blank unchanged, the circular flat blank is subjected to single-stage stamping deformation using a deep drawing die LS01. The stamping depth is greater than Hmm to ensure complete subsequent forming. The screen forming process is controlled, resulting in curved surface deformation without structural deformation, thus obtaining a single-stage stamped part, i.e., a curved screen. For example... Figure 4 The image shows the structure of the deep drawing die LS01 used in this step;

[0073] S3: The curved screen obtained in step S2 is subjected to secondary micro-stamping and shaping using a stamping machine to produce a pleated curved screen. Simultaneously, the ends of the screen are cut. Specifically:

[0074] S31: Secondary Stamping Deformation: The curved screen obtained in step S2 is placed in the processing position of a stamping machine. A deep drawing die LS02 is used to perform secondary stamping deformation on the curved screen. The wrinkling formation in the middle and bottom areas of the screen is controlled. During the wrinkling formation process in the middle and bottom areas of the screen, a curved surface deformation occurs, but no structural deformation occurs, resulting in a secondary stamped deformed part. For example... Figure 5 The image shows the structure of the deep drawing die LS02 used in this step;

[0075] S32: Initial shaping: After two stages of stamping deformation, the processing position of the secondary stamping deformation part remains unchanged. A folding shaping die is used to shape the secondary stamping deformation part and correct the overall shape of the screen surface, including the initial folding shaping, to obtain a quasi-finished stamping part with folds.

[0076] S33: Secondary shaping and blanking: After the initial shaping, keep the processing position of the semi-finished stamping part fixed, use the pleated shaping-cutting composite mold to perform secondary shaping on the finished stamping part, perform final shaping on the screen surface and pleats, and cut the bottom of the finished stamping part to form a round flat end shell to obtain the finished stamping part.

[0077] S34: Stamping Sample Inspection: Inspect the shape and size of the curved surface, wrinkled surface, and micro-holes on the curved surface of the finished stamping parts to see if they meet the size and accuracy requirements of the screen mesh for the wrinkled surface.

[0078] Example 2:

[0079] This embodiment is basically the same as Embodiment 1, except that in step S2, a spinning method is used to form the curved screen, and in step S3, a rolling method is used to form the pleated curved screen. In actual manufacturing, different forming methods can be selected and combined according to existing conditions or requirements. Steps S23 and S31 of this embodiment are specifically as follows:

[0080] S23: Spinning Deformation: After cutting and blanking, keeping the processing position of the circular flat blank unchanged, the circular flat blank is spun and deformed using a spinning deformation die. The spinning depth is greater than Hmm to ensure complete subsequent forming. During spinning, the die is fed up and down as a whole, and the spinning balls connected to springs on both sides of the die are fed along the generatrix direction. Iron rods are connected to the inner sides of the springs to ensure that the springs do not bend or deform during the feeding process. The screen forming is controlled; during the screen forming process, a curved surface deformation occurs without structural deformation, resulting in a spun deformed part, i.e., a curved screen. Figure 6 The diagram shows the structure of the spinning die used in this step.

[0081] S31: Roll forming deformation: Place the spun part obtained in step S2 into the processing position of the roll forming machine, change the roll forming die, and use a forming deformation die to roll form the spun part. During roll forming, the curved screen is rolled and shaped by the roller dies on both sides of the curved screen and the forming die on the inner side. The angle of the rollers on both sides of the curved screen can be changed over time to improve forming efficiency. Control the wrinkling formation in the middle and bottom areas of the screen. During the wrinkling formation process in the middle and bottom areas of the screen, curved surface deformation occurs without structural deformation, resulting in a roll-formed part. Figure 7 The diagram shows the structure of the forming deformation mold used in this step.

[0082] The remaining steps are the same as in Example 1.

[0083] Example 3:

[0084] The method for forming small-sized, thin-walled, pleated filter screens for hydraulic systems is implemented according to the following steps:

[0085] S1. Using electron beam cutting, a surface structure with a large aspect ratio of micro-perforated holes is processed on the original plate to form a surface micro-perforated plate.

[0086] S2. By unfolding the pleated surface of the pleated filter model, the dimensions of each part of the unfolded curved surface are fitted. Then, the micro-perforated plate obtained in step S1 is stamped / spun into a curved screen by a stamping / spinning machine, and the ends of the curved screen are cut at the same time.

[0087] S3. The curved screen obtained in step S2 is stamped / rolled and shaped using a stamping / rolling machine to produce a pleated curved screen, and the ends of the pleated curved screen are cut at the same time.

Claims

1. A method for forming small-sized thin-walled pleated filter screens for hydraulic systems, characterized in that, The specific steps are as follows: S1. Using electron beam cutting, a surface structure with a large aspect ratio of micro-perforated holes is processed on the original plate to form a surface micro-perforated plate. S2. By unfolding the pleated surface of the pleated filter model, the dimensions of each part of the unfolded curved surface are fitted. Then, the micro-perforated plate obtained in step S1 is stamped / spun into a curved screen by a stamping / spinning machine, and the ends of the curved screen are cut at the same time. S3. The curved screen obtained in step S2 is rolled and shaped using a rolling mill to produce a pleated curved screen, and the ends of the pleated curved screen are cut at the same time. Step S2 is as follows: S21. Determine the dimensions of each part of the curved surface after the pleated filter model is unfolded, and make the deep drawing deformation die LS01 for stamping / spinning according to the dimensions; S22. Cutting and blanking: Place the micro-perforated flat plate obtained in step S1 into the processing position of the stamping / spinning machine. According to the dimensions obtained in step S21, use the cutting die to cut and blank the material to obtain a circular flat plate blank. S23, One-time deformation: Keep the processing position of the circular flat blank unchanged, set the stamping / spinning process parameters, and use the deep drawing deformation die LS01 to stamp / spin deform the circular flat blank. The stamping / spinning depth is greater than the total height of the pleated filter screen after unfolding. After stamping / spinning, a curved screen is obtained. Step S21 is as follows: Unfold the pleated surface of the pleated filter model, and set the center of the circle on the open side of the filter model as the zero point. This zero point is H mm away from the center point of the head. Then, starting from the zero point plane, measure the unfolded length of the corresponding filter pleat every h mm. This length is the circumference of the plane circle corresponding to the curved screen to be processed in step S2. From this, the radius of the plane circle corresponding to the curved screen can be obtained. The radius data is fitted with the corresponding distance from the top of the sphere to obtain a quadratic curve. Rotating this curve along the y-axis will yield a simplified diagram of the curved screen. Based on this curve and the simplified diagram, the deep drawing deformation mold LS01 is made. Step S3 is as follows: S31. Secondary Deformation: Place the curved screen obtained in step S2 into the processing position of the rolling machine, set the rolling process parameters, use the deep drawing deformation die LS02 to roll and deform the curved screen, control the wrinkle formation in the middle and bottom areas of the screen, and obtain the secondary deformed part after rolling is completed. S32. Initial Correction: Keeping the processing position of the secondary deformed part unchanged, the overall shape of the curved surface of the secondary deformed part is corrected by using a folding correction mold, including the initial folding correction, to obtain a quasi-finished part with folds. S33. Secondary Shaping and Blanking: Keeping the processing position of the pre-finished part unchanged, a pleat-shaping-cutting composite mold is used to perform secondary shaping on the curved surface and pleats of the finished part, while cutting the bottom of the finished part to form a round flat end shell to obtain the finished part. S34. Sample inspection: Inspect the shape and size of curved surfaces, wrinkled surfaces, and micropores on curved surfaces of finished parts.

2. The method for forming a small-sized thin-walled pleated filter screen for a hydraulic system according to claim 1, characterized in that, Step S1 is as follows: S11. Fix the original sheet material onto the electron beam processing platform; S12. Import the micro-hole pattern to be processed into the equipment and set the electron beam processing parameters; S13. Start the electron beam processing platform and process the surface structure of the large depth-to-diameter ratio micro-hole according to the set processing trajectory to form a surface micro-hole plate. S14. Processing completed. Remove the surface micro-perforated plate.

3. The method for forming a small-sized thin-walled pleated filter screen for a hydraulic system according to claim 1, characterized in that, During the deformation process in step S23 or step S31, surface appearance deformation occurs, but structural deformation does not occur.

Images