Multi-station valve element working blind groove machining device and machining method

Abstract

The invention discloses a multi-station valve element working blind groove machining device and method, and belongs to the technical field of aviation mechanical engineering. The device comprises a positioning and aligning assembly and a multi-station electrode, the valve element is provided with a lengthened section which is accurately matched with the positioning and aligning assembly, and the multi-station electrode comprises one rough machining position electrode and two finish machining position electrodes. According to the method, radial and axial positioning of the valve element is achieved through the positioning alignment assembly, rough machining and finish machining are completed through one-time tool setting of the multi-station electrode, and errors caused by multiple times of alignment are avoided. The problems that the coplanarity error of discontinuous working edges of the valve element is large, and the qualified rate of working sharp edges is low are solved, the machining period is shortened, and the machining efficiency and the product qualified rate are improved.

Description

Technical Field

[0001] This invention belongs to the field of aerospace mechanical engineering technology, and relates to a multi-position valve core working blind groove processing device and processing method. Background Technology

[0002] In a servo control system, the valve core and valve sleeve form a spool valve pair. The relative motion between the two controls the opening size of the load output window, thereby achieving the purpose of controlling the output flow or output pressure. In order to achieve precise control of flow and pressure, strict requirements are put forward on the dimensional and positional tolerances such as the sharpness and coplanarity of the working edge of the valve core that forms the load output window.

[0003] Common valve cores have a working edge that is the entire circumference. To further control small flow outputs without changing the valve core diameter, a valve core with a discontinuous working edge and multiple blind grooves is currently being developed. To ensure the circumferential coplanarity of the axial end faces of the multiple blind grooves evenly distributed on the outer surface of this valve core and to achieve micron-level precision in the sharp edges of the working edges, electrical discharge machining (EDM) is currently used. The valve core is positioned using its outer surface and oriented by internal pin holes. Because each side of the internal pin hole on the valve core has a discontinuous working edge (see...),... Figure 2 Therefore, when machining the working edges on both sides of the valve core, multiple blind grooves on one side of the working edge need to be machined first using electrodes. Each blind groove requires one roughing electrode discharge machining and one finishing electrode machining to be finally formed. Each time the electrode is changed, it needs to be repositioned and aligned, making it impossible to ensure that the electrode positioning is consistent in both machining operations. Therefore, it is difficult to guarantee the circumferential coplanarity of the axial end face of the blind groove on one side in a single machining operation, requiring continuous rework and correction. Similarly, the machining of the blind grooves on the other side of the working edge has the same problem. Moreover, since the blind grooves on both sides of the working edge are machined separately, the coplanarity error of the two working blind grooves on the same axis of the valve core is very large, requiring rework and correction. This results in a long valve core machining cycle and a low coplanarity pass rate for discontinuous working edges. Considering the wear of the machining electrodes during the discharge process, especially the fastest wear at the electrode tip, there is a problem of low pass rate for working sharp edges in a single finishing operation.

[0004] Therefore, it is essential to find a machining device and method for processing the working blind groove of a multi-position valve core. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a multi-station valve core working blind groove processing device and method to solve the problems of large coplanarity error of discontinuous working edges of the valve core and low pass rate of working sharp edges.

[0006] The present invention provides a multi-station valve core working blind groove machining device, including a positioning and alignment component and a multi-station electrode; one end of the multi-station valve core to be machined is provided with an extension section, and the positioning and alignment component cooperates with the extension section to clamp and fix the valve core to be machined; the multi-station electrode includes a clamping section and a machining section, the clamping section is used to fix it on an electrical discharge machine, and the machining section is used to machine the blind groove on the valve core.

[0007] Furthermore, the positioning and alignment component includes a positioning seat, a directional pin, and a tightening screw; the positioning seat is fixed to the magnetic chuck of the EDM equipment by a magnetic attraction device, and the positioning seat has a V-shaped groove at its center, with the extended section of the valve core placed in the V-shaped groove to achieve radial positioning; the side of the positioning seat has a directional pin hole, and the directional pin passes through the directional pin hole and the pin hole on the extended section of the valve core to fix the axial position of the valve core; the side of the positioning seat facing the V-shaped groove has a screw hole, and the tightening screw cooperates with the screw hole to fix the valve core.

[0008] Furthermore, the positioning seat is a cuboid with a parallelism of no more than 0.005 mm between its upper and lower surfaces, and a perpendicularity of no more than 0.005 mm between the V-shaped surface of the V-groove and the upper and lower surfaces; the axis of the directional pin hole is perpendicular to the machined surface with a perpendicularity error of no more than 0.01 mm, and the diameter of the directional pin hole is slightly larger than the diameter of the pin hole on the extended section of the valve core.

[0009] Furthermore, the directional pin is a cylinder with a straightness error of no more than 0.01 mm within its length range, and its diameter is a transition fit with the pin hole diameter of the extended section of the valve core.

[0010] Furthermore, the coaxiality between the outer circle of the extended section of the valve core and the outer circle of the working core is no greater than 0.001mm; the pin hole on the extended section and the pin hole inside the valve core are machined in one clamping operation, and the parallelism between their axes is no greater than 0.01mm.

[0011] Furthermore, the processing section of the multi-station electrode includes one roughing electrode and two finishing electrodes; the bottom of the roughing electrode is provided with a positioning boss, the perpendicularity error between the small end faces on both sides of the positioning boss and the bottom surface of the roughing electrode does not exceed 0.001mm, and the positioning boss protrudes 0.4mm from the bottom surface of the electrode.

[0012] Furthermore, the coplanarity error of the left and right end faces of the two finishing electrodes does not exceed 0.001mm, and the length of the two finishing electrodes is consistent with the distance between the working edges on both sides of the valve core; the length of the roughing electrode is 0.02mm shorter than the length of the finishing electrode.

[0013] This invention also proposes a machining method for realizing the working blind groove of the valve core based on the above-designed machining device, including the following steps: Step S1: Place the bottom surface of the positioning seat on the magnetic chuck of the EDM equipment, and use the end face with the threaded hole as the machining reference. Step S2: Place the extended section of the valve core into the V-groove of the positioning seat, pass the directional pin through the directional pin hole of the positioning seat and the pin hole of the extended section of the valve core, and fix the valve core with the tightening screw; Step S3: Locate the rough machining electrode. Rotate the positioning seat 45° clockwise relative to the machining datum as the starting point of the machining. Take the outer circle of the working edge of the valve core as the radial machining starting point. Use the side of the positioning boss of the rough machining electrode to find the starting end face of the blind groove to be machined in the valve core as the axial starting point. Step S4: Use the roughing electrode to discharge machine four working blind grooves evenly distributed on the outer circle of the valve core. Step S5: After rough machining is completed, control the multi-station electrode to move horizontally so that the middle finishing electrode is moved to the rough machining electrode position to machine two working blind slots. Step S6: Continue to horizontally move the multi-station electrode so that another finishing electrode is moved to the above-mentioned finishing position to process the remaining two working blind slots; Step S7: Remove the extended section of the valve core by wire cutting to complete the machining.

[0014] The beneficial effects of this invention are that it provides a method for machining the working blind groove of a valve core, including a positioning and alignment device and a multi-station electrode. Utilizing the self-centering principle of a V-shaped surface, an extended section is set up so that the outer circular surface of the valve core working edge and the outer circular surface of the extended section are collinear. Simultaneously, the conventional small electrode is improved into a multi-station long electrode, and all roughing and finishing processes are completed in one go through the positioning boss of the roughing electrode, avoiding installation errors introduced by multiple alignments, and greatly shortening the alignment time, thus improving machining efficiency. By setting two finishing electrodes, the defective working edge caused by electrode wear is reduced. The improved multi-station long electrode can simultaneously machine the blind groove of the working edge of the valve core's two protruding shoulders, reducing the machining time by half, thereby greatly improving machining efficiency. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Among them, 1. positioning seat; 2. directional pin; 3. tightening screw; 4. valve core; 5. multi-position electrode.

[0018] Figure 2This is a schematic diagram of the valve core structure.

[0019] Figure 3 This is a schematic diagram of the positioning seat structure.

[0020] Figure 4 This is a schematic diagram of a multi-station electrode structure. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0023] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0025] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0027] like Figures 1-4 As shown, the multi-station valve core working blind groove processing device designed in this invention includes a positioning and alignment component and a multi-station electrode; An extension section is reserved at one end of the multi-station valve core to be processed. The positioning and alignment component cooperates with the extension section to clamp and fix the valve core to be processed. The multi-station electrode includes a clamping section and a multi-station electrode; the clamping section is fixed on the EDM equipment, and the multi-station electrode is used to process blind grooves on multi-station valve cores.

[0028] The positioning and alignment device includes a positioning seat 1, a directional pin 2, a tightening screw 3, and a valve core 4. The positioning seat is fixed to the magnetic chuck of the EDM equipment by a magnetic attraction device, and a V-shaped groove is provided at the center position. The extended section of the valve core is placed in the V-shaped groove of the positioning seat for radial positioning of the valve core. A directional pin hole is provided on the side of the positioning seat, and the directional pin passes through the positioning pin hole and the pin hole on the extended section of the valve core to fix the axial position of the valve core. A screw hole is provided on the side of the positioning seat facing the V-shaped groove, which, together with the tightening screw, fixes the valve core.

[0029] The positioning seat is rectangular in shape, requiring the parallelism of its upper and lower surfaces to be no greater than 0.005 mm, and the perpendicularity of the internal V-shaped surface of the positioning seat to the upper and lower surfaces to be no greater than 0.005 mm. The directional pin hole passes through the V-shaped surface of the V-groove, and the axis of the directional pin hole is perpendicular to the machined surface, with a perpendicularity error of no greater than 0.01 mm. The diameter of the directional pin hole is slightly larger than the pin hole on the extended section of the valve core, thereby ensuring that the valve core is pressed tightly into the V-groove of the positioning seat under the action of the tightening screw.

[0030] The directional pin is cylindrical, with a straightness error of no more than 0.01 within its length range, and its diameter maintains a transition fit with the pin hole diameter of the extended section of the valve core.

[0031] The valve core has an extended end, and the coaxiality between the outer circle of the extended end and the outer circle of the working end is required to be no greater than 0.001. A directional pin hole is provided in the middle of the extended end, which is required to be clamped and machined with the internal pin hole of the valve core in one go to ensure that the parallelism of the two axes is no greater than 0.01mm.

[0032] The multi-station machining electrode is fixed to the EDM equipment via a clamping section. It has one roughing electrode and two finishing electrodes to achieve roughing and finishing of the working blind groove, respectively. The bottom of the roughing electrode is provided with a positioning boss for positioning when machining begins.

[0033] The coplanarity error of the left and right end faces of the two finishing electrodes in the multi-station machining electrode does not exceed 0.001mm, to ensure consistent axial positioning during the two finishing processes and that the discontinuous working edges after machining are coplanar. The length of the two finishing electrodes is consistent with the distance between the working edges on both sides of the valve core, to ensure that the blind grooves on both sides of the valve core are machined as a whole during electrode machining, and that the sides of the blind grooves on both sides of the valve core are coplanar along the same axis of the valve core. The length of the roughing electrode is slightly smaller than that of the finishing electrode by 0.02mm, and the bottom surface is provided with an integrated positioning boss. The perpendicularity error between the small end faces on both sides of the positioning boss and the bottom surface of the roughing electrode does not exceed 0.001mm, and the positioning boss protrudes 0.4mm from the bottom surface of the electrode to avoid interference of the positioning boss with the outer circular surface of the small shaft section in the middle of the valve core when the machining electrode moves into place.

[0034] In another aspect, the present invention also proposes a method for machining a working blind groove in a valve core, the method comprising the following steps: Step 1: Place the bottom of the positioning seat on the magnetic chuck of the EDM equipment, with the end face with the threaded hole facing forward and used as the machining reference; Step 2: Place the extended section of the valve core into the V-groove of the positioning seat; Step 3: Pass the directional pin through the locating pin hole on the locating seat and the pin hole on the extended section of the valve core at the same time, and fix the valve core by tightening the screw. Step 4: Alignment. Align the roughing electrode. Rotate the positioning seat 45° clockwise relative to the machining datum as the starting point of the machining. Use the outer circle of the working edge of the valve core as the starting point of the radial machining. Use the side of the positioning boss on the roughing electrode to find the starting end face of the blind groove to be machined in the valve core as the starting point of the axial machining. Step 5: Electrical discharge machining, rough machining of 4 working blind grooves evenly distributed on the outer circle of the valve core; Step 6: After rough machining is completed, control the equipment holding the multi-station electrode to move horizontally, so that the finishing electrode position in the middle of the multi-station electrode is moved to the rough machining electrode position, and use the finishing electrode to machine two working blind grooves. Step 7: Control the equipment holding the multi-station electrode to continue to move horizontally, so that another finishing electrode on the multi-station electrode moves to the position of the previous finishing electrode, and use another finishing electrode to process the other two working blind slots.

[0035] Step 8: Remove the extended section of the valve core by wire cutting to complete the valve core machining.

[0036] Example 1, see appendix Figure 2Taking the machining of the working blind groove of a certain type of valve core as an example, it includes two discontinuous working edges on two circumferential surfaces.

[0037] like Figure 1 As shown, a positioning and alignment device is characterized by comprising a positioning seat, a directional pin, a tightening screw, and a valve core.

[0038] like Figure 3 As shown, the positioning seat is precision machined. The outer shape of the positioning seat is machined by surface grinding to ensure that the parallelism of the upper and lower surfaces is no greater than 0.005mm. The internal V-shaped surface of the positioning seat is precision machined by slow wire EDM to ensure that the perpendicularity with the upper and lower surfaces is no greater than 0.005mm, thereby ensuring the centering requirement of the outer circle of the extended end of the valve core. The directional pin hole is first rough machined and then finished by slow wire EDM to ensure that the parallelism between the axis of the directional pin hole and the front and rear surfaces of the positioning seat is no greater than 0.01mm, thereby ensuring the accurate direction of the positioning pin after the positioning seat is aligned and reducing the alignment process.

[0039] like Figure 2 As shown, the extended end of the valve core is precision machined. The internal pin hole and the directional pin hole are machined in one clamping to ensure that the parallelism of their axes is no greater than 0.01mm. The outer circular surface of the working edge of the valve core and the outer circular surface of the extended end are ground in one clamping to ensure that their coaxiality is no greater than 0.0015mm. This ensures that the outer circular surface of the working edge of the valve core is perpendicular to the bottom surface of the positioning seat after the extended section of the valve core is clamped into the V-groove of the positioning seat.

[0040] like Figure 4 As shown, a multi-station electrode is precision machined. The machining of the three-station electrode along its length and the positioning boss is completed in one pass using a slow wire EDM process. This ensures that the coplanarity error of the left and right end faces of the three electrodes does not exceed 0.001 mm, and the center error of the length of the three electrodes does not exceed 0.002 mm. This achieves consistent positioning during roughing and finishing, and ensures that discontinuous working edges are coplanar after machining. By fine-tuning the length of the rough-machined electrode, the lengths at both ends of the rough-machined electrode are slightly smaller than the length of the finishing electrode by 0.02 mm to allow for finishing allowance. An integrated positioning boss is provided on the bottom surface of the rough-machined electrode. The small end faces of the positioning boss are machined on both sides using a slow wire EDM process, ensuring that the perpendicularity error between the small end faces of the positioning boss and the bottom surface of the rough-machined electrode does not exceed 0.001 mm, and the positioning boss protrudes no more than 0.4 mm from the bottom surface of the electrode to avoid interference with the outer circular surface of the valve core's middle small shaft section when the machined electrode reaches its position.

[0041] Before processing, place the positioning seat on the magnetic chuck of the EDM equipment, with the end face with the threaded hole facing forward; place the outer circle of the extended section of the valve core on the V-shaped surface of the positioning seat, rotate it so that the positioning pin passes through the directional pin hole of both the positioning seat and the valve core at the same time, and fix the valve core by tightening the screw. At this point, the valve core clamping is completed.

[0042] During machining, the multi-station electrode is clamped onto the machining equipment so that the electrode length direction is along the valve core axial direction, and the electrode is aligned. The machining reference surface of the positioning seat is rotated 45° as the starting machining direction. The working outer circle is used as the radial machining starting point. The end face of the blind groove shoulder to be machined on the valve core is used as the axial starting point. The roughing electrode is used to machine the four working blind grooves in the circumferential direction on both sides of the valve core shoulder. The finishing electrode is used to machine the two working blind grooves in the circumferential direction. The finishing electrode is used to machine the other two working blind grooves in the circumferential direction.

[0043] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A multi-station spool working blind groove machining device, characterized in that, The application relates to a positioning and aligning assembly and a multi-station electrode, one end of a multi-station valve core to be machined is provided with an extended section, the positioning and aligning assembly cooperates with the extended section to clamp and fix the valve core to be machined, the multi-station electrode comprises a clamping section and a machining part, the clamping section is used for being fixed on an electric spark device, and the machining part is used for machining blind grooves on the valve core.

2. The multi-station spool work blind groove machining device according to claim 1, characterized in that, The positioning and aligning assembly comprises a positioning seat, a directional pin and a tightening screw, the positioning seat is fixed on a magnetic chuck of the electric spark device through a magnetic attraction device, a V-shaped groove is arranged in the center of the positioning seat, the extended section of the valve core is arranged in the V-shaped groove to realize radial positioning, a directional pin hole is arranged on the side surface of the positioning seat, the directional pin passes through the directional pin hole and a pin hole on the extended section of the valve core to fix the axial position of the valve core, and a screw hole is arranged on the side surface of the positioning seat opposite to the V-shaped groove, the tightening screw cooperates with the screw hole to fix the valve core.

3. The multi-station spool work blind groove machining device according to claim 2, characterized in that, The positioning seat is a cuboid, the parallelism error of the upper and lower surfaces is not greater than 0.005 mm, the perpendicularity error of the V-shaped surface of the V-shaped groove and the upper and lower surfaces is not greater than 0.005 mm, the axis of the directional pin hole is perpendicular to the machining surface, the perpendicularity error is not greater than 0.01 mm, and the diameter of the directional pin hole is slightly greater than the diameter of the pin hole on the extended section of the valve core.

4. The multi-station spool work blind groove machining device according to claim 2, characterized in that, The directional pin is a cylinder, the straightness error of the directional pin in the length range is not greater than 0.01 mm, and the diameter of the directional pin is in transition fit with the diameter of the pin hole on the extended section of the valve core.

5. The multi-station spool work blind groove machining device of claim 1, wherein, The coaxiality error of the outer circle of the extended section of the valve core and the working outer circle is not greater than 0.001 mm, the pin hole on the extended section and the internal pin hole of the valve core are processed through one-time clamping, and the parallelism error of the axes of the two is not greater than 0.01 mm.

6. The multi-station spool work blind groove machining device of claim 1, wherein, The machining part of the multi-station electrode comprises one rough machining station electrode and two fine machining station electrodes, the bottom of the rough machining station electrode is provided with a positioning boss, the perpendicularity error of the small end surfaces on the two sides of the positioning boss and the bottom surface of the rough machining station electrode is not greater than 0.001 mm, and the positioning boss protrudes the bottom surface of the electrode by 0.4 mm.

7. The multi-station spool work blind groove machining device according to claim 6, characterized in that, The coplanarity error of the left and right end surfaces of the two fine machining station electrodes is not greater than 0.001 mm, the lengths of the two fine machining station electrodes are consistent with the distance between the two working edges of the valve core, and the length of the rough machining station electrode is smaller than the length of the fine machining station electrode by 0.02 mm.

8. A method for machining a blind groove of a spool working chamber realized by means of a machining device according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: Step S1, placing the bottom surface of the positioning seat on the magnetic chuck of the electric spark device, and taking the end surface with the threaded hole as a machining reference; Step S2, placing the extended section of the valve core in the V-shaped groove of the positioning seat, passing the directional pin through the directional pin hole of the positioning seat and the pin hole on the extended section of the valve core, and fixing the valve core through the tightening screw; Step S3, aligning the rough machining station electrode, rotating the positioning seat by 45 degrees clockwise relative to the machining reference as a machining starting direction, taking the outer circle of the working edge of the valve core as a radial machining starting point, and taking the side surface of the positioning boss of the rough machining station electrode as an axial starting point; Step S4, discharging and machining four uniformly distributed working blind grooves on the outer circle of the valve core through the rough machining station electrode; Step S5, after the rough machining is completed, controlling the horizontal translation of the multi-station electrode to move the middle fine machining station electrode to the position of the rough machining station electrode, and machining two working blind grooves; Step S6, continue to horizontally translate the multi-station electrode, so that another finishing station electrode moves to the above-mentioned finishing position, and the remaining 2 working blind grooves are processed; Step S7, the wire cutting removes the valve core lengthening section, and the processing is completed.

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