Pressing method and turning method of cushion block for sintering A-95 porcelain

Abstract

The pressing method comprises the following steps: preparing a flat plate gasket with a hole in the middle and the thickness of 10-15mm by adopting dry pressing molding, and controlling the pressing density of the flat plate gasket; then the gasket is positioned to a turning system through a robot, after secondary centering is conducted through an inner diameter pneumatic three-jaw and pneumatic pressing is conducted through a nylon block, synchronous rotation is conducted, and an outer diameter and 45-degree step structure is turned in sequence; after machining, dust is automatically blown and removed, excess materials are recycled, the step diameter and the step height size are detected through laser according to the set frequency, and alarming and shutdown are conducted when the difference is out of tolerance. The technical problems that the turning efficiency is low, the raw material utilization rate is low and the machining quality is unstable due to the fact that the outer diameter of a traditional isostatic pressing forming blank is irregular are solved.

Description

Technical Field

[0001] This application relates to the field of white porcelain processing technology for metallized ceramic shells of vacuum interrupters, specifically to a pressing method and machining method for a pad block used in A-95 porcelain sintering. Background Technology

[0002] Vacuum interrupters are core components of medium- and high-voltage power switches, widely used in high-voltage power transmission and distribution systems, as well as in metallurgy, mining, petroleum, chemical, railway, broadcasting, communications, and industrial high-frequency heating systems. The metallized ceramic shell, a key component, requires its white ceramic blank to be densified through high-temperature sintering. During the A-95 ceramic sintering process, to control the shrinkage and deformation of the cylindrical ceramic shell blank, conventional processes involve placing a pad of the same material at each end of the shell. The pads shrink and constrain the product's shrinkage. In existing technologies, the pad blanks are generally formed using isostatic pressing, resulting in a single cylindrical structure with an irregular outer diameter. Subsequently, it needs to be clamped on a conventional lathe for sequential outer diameter turning, step turning, and slicing separation—a cumbersome process reliant on manual operation.

[0003] The existing method of isostatic pressing + single-machine turning results in a raw material utilization rate of only about 50% for the pad blanks. The turning cycle is long, the repeatability is low, and the dimensional consistency is poor, making it difficult to meet the requirements of automated mass production with high efficiency, high stability, and high material utilization. Summary of the Invention

[0004] The purpose of this invention is to provide a pressing and machining method for a pad block used in A-95 ceramic sintering, which can solve the technical problems of low machining efficiency, low raw material utilization, and unstable processing quality caused by the irregular outer diameter of the blank formed by traditional isostatic pressing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of the present invention provides a method for pressing a spacer block for A-95 ceramic sintering, comprising the following steps: S1. Determine the structural parameters of the flat plate gasket. The flat plate gasket is a flat plate structure with a hole in the middle, and the thickness of the flat plate gasket is set to 10-15mm. S2, A-95 ceramic raw material is pressed using a dry pressing method to obtain a flat gasket that meets the structural parameters of S1; S3, control the density of the flat gasket during the pressing process to obtain the pressed flat gasket.

[0006] In one alternative embodiment, the outer diameter of the flat gasket is uniformly determined based on the outer diameter dimensions of products with similar specifications.

[0007] In one alternative embodiment, the diameter of the central hole in the flat pad is 30 mm.

[0008] A second aspect of the present invention provides a method for machining a spacer block for A-95 ceramic sintering, for machining a flat spacer block obtained by the aforementioned method, comprising the following steps: M1. Transfer and position the flat pad onto the worktable of the machining system; M2. Pneumatically press the positioned flat pad and rotate it together with the worktable; M3. The cutting tool is controlled by the program to turn the rotating flat plate. First, its outer diameter is turned, and then the step structure on it is turned by the forming tool. The step structure is used to match the inner diameter of the ceramic blank to be sintered to limit shrinkage.

[0009] In one optional embodiment, during the M1 process, a robot picks up and places a flat plate pad. The center of the worktable is equipped with an inner diameter pneumatic three-jaw chuck. By driving the inner diameter pneumatic three-jaw chuck to open the middle hole of the flat plate pad, the flat plate pad is repositioned.

[0010] In one alternative embodiment, during the M2 process, a clamping cylinder located directly above the center of the worktable drives a nylon block to press down, thereby fixing the flat plate pad after secondary positioning.

[0011] In an optional embodiment, an M4 is also included, which, after machining, uses a high-pressure air pipe to blow away the surface dust of the pad and uses a dust collection pipe to collect the dust.

[0012] In an alternative embodiment, an M5 is also included, wherein scrap generated during the turning process is collected by a recycling system located at the bottom of the lathe.

[0013] In one optional embodiment, an automatic size detection step is also included: after the set quantity is machined, a laser measuring instrument is used to automatically detect the step diameter and platform height of the machined pads.

[0014] In one optional embodiment, during the automatic size detection step, when the detected size exceeds a preset size deviation area, the equipment alarms and suspends processing.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a pressing method for a spacer block for sintering A-95 ceramics. By designing the spacer block as a flat plate structure with a hole in the middle and a thickness of 10-15mm, and using dry pressing to replace isostatic pressing, the blank shape is regular and the size is consistent. Combined with pressing density control, the sintering compatibility is ensured. This supports high-precision positioning, stable clamping and efficient turning in subsequent automated turning.

[0016] This invention discloses a method for machining a pad for A-95 ceramic sintering. The flat plate structure facilitates robot gripping and pneumatic three-jaw secondary centering, avoiding the eccentricity problem of traditional irregular blank clamping. Due to the small outer diameter tolerance of the dry-pressed blank, the machining allowance is significantly reduced, and the raw material utilization rate is increased from about 50% to over 85%. Because the entire process of automatic feeding, machining, dust blowing, inspection, and palletizing is a closed-loop operation, the single-piece processing cycle is shortened by more than 60%, effectively solving the technical problems of low efficiency, poor consistency, and serious raw material waste in traditional processes. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a pressing method for a pad block used in the sintering of A-95 ceramic according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram illustrating a method for machining a pad for sintering A-95 ceramic according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the pad block used for sintering A-95 ceramic in an embodiment of the present invention.

[0020] In the diagram, 1 represents the pad block. Detailed Implementation

[0021] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0026] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] See Figure 1 and Figure 3 This invention provides a method for pressing a spacer block for A-95 ceramic sintering, comprising the following steps: S1. Determine the structural parameters of the flat plate gasket. The flat plate gasket is a flat plate structure with a hole in the middle. The thickness of the flat plate gasket is set to 10–15 mm. S2, A-95 ceramic raw material is pressed using a dry pressing method to obtain a flat gasket that meets the structural parameters of S1; S3, control the density of the flat gasket during the pressing process to obtain the pressed flat gasket.

[0031] The S1 flat plate gasket is a flat plate structure with a hole in the middle. Specifically, the flat plate gasket is a circular thin plate with a through hole in the center that runs through the thickness direction. This through hole is used for mechanical positioning (such as pneumatic three-jaw clamping), visual recognition reference and airflow channel in subsequent automated transmission. The through hole is circular in shape and has a diameter of 30 mm. The outer diameter of the flat plate gasket is uniformly set to 100 mm. This value is determined based on the statistical distribution of the outer diameter of similar A-95 ceramic shells, taking into account both universality and mold standardization requirements. The dry pressing process in S2 specifically refers to: A-95 ceramic powder, which has been spray-granulated and has a moisture content controlled at 0.3–0.6 wt%, is loaded into a steel female mold cavity with the aforementioned structural parameters. Densification is achieved through unidirectional pressure applied by a male mold. The pressing pressure is 120–180 MPa, the holding time is 8–15 s, and the density range of the A-95 ceramic powder is 2.35–2.45 g / cm³. The inner wall of the female mold is mirror-polished and coated with zinc stearate release agent to reduce the frictional resistance between the powder and the mold wall, ensuring demolding integrity and surface roughness ≤ Ra 3.2 μm. The core difference between this dry pressing process and isostatic pressing lies in: directly imparting a precise geometric contour to the blank through rigid mold limiting, avoiding dimensional drift caused by the elastic deformation of the rubber sleeve in isostatic pressing, so that the outer diameter tolerance can be stably controlled within ±0.15 mm, and the thickness consistency reaches ±0.2 mm, providing a highly repeatable positioning reference for the subsequent fully automated machining system.

[0032] In S3, controlling the density of the flat plate gasket during the pressing process specifically refers to adjusting the pressing parameters through closed-loop feedback to achieve target green compact density control.

[0033] In this embodiment, by using dry pressing instead of isostatic pressing, the problem of excessive machining allowance caused by the irregular outer diameter of the traditional blank is solved; by limiting the thickness range and coordinating density control, the problems of dimensional deviations and roundness degradation caused by the sintering shrinkage mismatch between the pad 1 and the ceramic shell are solved; by setting a central through hole and clarifying its functional orientation, the problem of the blank being unable to achieve precise positioning and continuous flow in automated production lines is solved. This invention achieves a unified high geometric accuracy, high density consistency, and high process reproducibility for the A-95 ceramic pad blank.

[0034] See Figure 2 The present invention also provides a method for machining a spacer block for A-95 ceramic sintering, for machining a flat spacer block obtained by the method, comprising the following steps: M1. Transfer and position the flat pad onto the worktable of the machining system; M2. Pneumatically press the positioned flat pad and rotate it together with the worktable; M3. The cutting tool is controlled by the program to turn the rotating flat plate. First, its outer diameter is turned, and then the step structure on it is turned by the forming tool. The step structure is used to match the inner diameter of the ceramic blank to be sintered to limit shrinkage.

[0035] In a more specific embodiment of the present invention, the positioning in M1 includes two stages: primary positioning and secondary fine positioning. The primary positioning is achieved by a V-groove, ensuring that the central axis of the flat pad is perpendicular to the conveying direction, the bottom surface is in contact with the conveyor belt, and the outer edge is roughly centered. The secondary positioning is completed in the subsequent M1 motion extension stage, where a six-axis industrial robot equipped with a vacuum suction cup picks up the flat pad, transfers it horizontally, and places it in the center area of ​​the turning system's worktable. At this point, the central hole of the flat pad is basically coaxial with the central through hole of the worktable. This positioning process does not rely on manual intervention, and the cycle time is ≤6 s / piece.

[0036] The turning system in M1 uses a rotary precision fixture platform with a 25 mm diameter through hole at the center of the table. The hole wall is hard anodized and is used to accommodate the inner diameter pneumatic three-jaw actuator, providing the structural basis for secondary positioning in M2. The table drive spindle is driven by a servo motor with a rated speed adjustable from 0 to 1200 rpm to meet the cutting speed requirements of different turning stages.

[0037] In a more specific embodiment of the invention, the pneumatic clamping finger in M2 applies a vertically downward clamping force through a single-acting double-guided cylinder positioned directly above the worktable, with a circular nylon clamping block fixedly connected to the piston rod end; the plate pad, rotating together with the worktable, rotates synchronously with the worktable, and the two are dynamically concentric through a floating connection structure, eliminating eccentric vibrations caused by accumulated assembly errors. This clamping method differs from traditional three-jaw external clamping or vacuum adsorption: the nylon clamping block is made of moderately soft and hard material, avoiding crushing of the plate pad surface caused by hard metal clamping heads; the double-guided cylinder ensures that the straightness of the clamping block's movement is better than 0.02 mm, suppressing the tilting of the plate pad induced by lateral forces; the synchronous rotation design eliminates relative sliding friction heat, preventing local temperature rise from causing changes in the microstructure of the A-95 ceramic.

[0038] In this embodiment, the robot provides a wide-range, high-speed flexible feeding capability, creating a prerequisite for subsequent precise positioning; the central through hole of the worktable and the inner diameter pneumatic three-jaw jack constitute a spatial constraint reference, ensuring the reliability and repeatability of mechanical cooperation; the elastic coating layer of the inner diameter pneumatic three-jaw jack forms a non-rigid contact with the hole wall of the flat plate gasket, which not only avoids the generation of micro-cracks in the brittle ceramic blank during clamping, but also compensates for the machining error of the hole wall through local plastic deformation; and the structural design of the inner diameter pneumatic three-jaw jack being higher than the worktable surface ensures that the tensioning force is entirely applied to the flat plate gasket and is not offset by the reaction force of the table surface.

[0039] In another embodiment of the present invention, M4 is also included. After machining, the surface dust on the pad block 1 is blown off using a high-pressure air pipe, and the dust is collected using a dust extraction pipe. The high-pressure air pipe is a stainless steel adjustable air circuit branch pipe, the end of which is connected to a flat fan-shaped nozzle and installed on a fixed bracket on the side rear of the lathe spindle box. After machining, the system judgment point is when the forming tool completes the stepped turning and retracts to a safe position in step M3, the piston of the clamping cylinder retracts to the initial position, the table speed drops to 0 rpm, and the positioning sensor confirms the stationary state.

[0040] The dust collection process using the suction pipe involves two stages of physical capture: the first stage is a cyclone separator that centrifuges and settles coarse particles with a diameter >10 μm into a removable dust collection bin at the bottom; the second stage is a HEPA filter unit that intercepts submicron-sized ceramic powder (0.3–10 μm in diameter) suspended in the airflow. The filter replacement cycle is set to trigger an alarm when the system operates continuously for 200 hours or when the pressure difference reaches 1.2 kPa. This two-stage structure balances the recovery rate of large particles with clean air emission requirements, and meets the requirement of a local ventilation dust removal system capture efficiency of ≥95% in GB / T 16758—2008 "Classification and Technical Conditions of Exhaust Hoods".

[0041] The directional blowing of high-pressure air provides initial kinetic energy and the driving force for dust to escape; the diagonal negative pressure field of the dust collection duct creates a spatially constrained airflow boundary, forcibly guiding the escaping dust to the collection area; the timing interlock between CNC and PLC ensures a closed-loop action logic, avoiding conflicts between dust blowing and compaction / rotation actions; the cyclone + HEPA dual-stage filtration structure is adapted to the wide particle size distribution characteristics of A-95 ceramic powder (D 10 ≈1.8 μm, D 90 (≈8.5 μm), ensuring that particles of different sizes are effectively captured.

[0042] This invention achieves controllable removal and closed-loop collection of residual dust on the surface of the vehicle rear pad block 1: because the high-pressure airflow is precisely applied to areas prone to dust accumulation, such as the step surface and the outer edge junction, it solves the problems of low efficiency, unstable cleanliness, and occupational health risks of personnel exposure to dust caused by manual wiping in the prior art.

[0043] In another embodiment of the present invention, M5 is also included, and the waste material generated during the turning process is collected by a recycling system located at the bottom of the lathe.

[0044] The recycling system includes an inclined guide plate made of stainless steel (SUS304) installed below the connection area between the lathe spindle box and the bed; a buffer collection bin located directly below the end of the guide plate, which is a rectangular sealed cavity with an open top; and a sealed transfer interface: the bottom of the collection bin is equipped with a DN80 standard flange interface for docking with an external vacuum conveying pipeline or a manual transfer trolley; the interface is equipped with a pneumatic butterfly valve and a silicone sealing ring to ensure that no dust escapes during the transfer process.

[0045] In another embodiment of the present invention, an automatic size detection step is also included: after the set quantity is machined, a laser measuring instrument is used to automatically detect the step diameter and platform height of the machined pad 1.

[0046] The machined pad 1 refers to the workpiece to be inspected that has completed all turning processes from M1 to M3, undergone dust removal by M4, and has not yet been removed from the worktable. Before inspection, the worktable stops rotating, the clamping cylinder remains in a downward pressure state, and the pneumatic three-jaw chuck maintains the clamping force to ensure that the pad 1 has no displacement or vibration during the inspection process. The surface of the pad 1 is dry and clean, with no residual coolant or metal debris interfering with laser reflection.

[0047] The step diameter refers to the outer diameter of the annular step on the pad 1 that is used to fit the inner diameter of the ceramic shell, that is, the diameter of the maximum projected circle of the step structure. This dimension is obtained by scanning at least three cross-sectional profiles along the radial direction of the pad 1 with a laser measuring instrument, and the average value is taken as the final measurement value. Its design tolerance zone is ±0.05 mm.

[0048] The platform height refers to the vertical height of the upper surface of the step relative to the main reference surface of the pad 1, that is, the axial distance from the lower end face of the pad 1 (the contact surface with the workbench) to the top surface of the step. During measurement, the laser probe first collects the height of the main area of ​​the pad 1 as the reference zero point, and then collects the height of the top surface of the step. The difference between the two is the platform height. This dimension also adopts the multi-point sampling mean method, with no less than 5 sampling points, evenly distributed around the circumference of the step. Its design tolerance zone is ±0.03 mm.

[0049] This invention enables process-oriented, automated, and non-contact sampling monitoring of the key geometric dimensions of the A-95 ceramic pad. Because the set quantity triggering mechanism is combined with the high precision and fast response characteristics of the laser measuring instrument, it solves the problem of gradual dimensional changes caused by tool wear, spindle thermal drift, or fixture loosening during long-term continuous turning.

[0050] In the automatic size detection step, when the detected size exceeds the preset size deviation area, the equipment alarms and suspends processing. Through the above steps, this invention achieves dynamic monitoring and real-time intervention of the stability of key dimensions during the machining of A-95 ceramic pads.

[0051] The measured dimensions refer to the actual values ​​of the step diameter and platform height output by the laser measuring instrument, both of which are acquired through non-contact two-dimensional / three-dimensional laser displacement sensors. The preset dimensional deviation areas are two independently defined tolerance zones: the step diameter tolerance zone is D... t ± 0.05 mm (e.g., if the target value is 32.6 mm, the allowable range is 32.55~32.65 mm), and the platform height tolerance zone is H. t ± 0.03 mm (for example, if the target value is 1.75 mm, the allowable range is 1.72 to 1.78 mm). This invention enables dynamic monitoring and real-time intervention of the critical dimensional stability during the machining process of the A-95 ceramic pad.

[0052] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for pressing a spacer block for sintering A-95 ceramic, characterized in that, Includes the following steps: S1, Determine the structural parameters of the flat plate gasket, wherein the flat plate gasket is a flat plate structure with a hole in the middle, and the thickness of the flat plate gasket is set to 10-15mm; S2, A-95 ceramic raw material is pressed using a dry pressing method to obtain a flat gasket that meets the structural parameters of S1; S3, control the density of the flat gasket during the pressing process to obtain the pressed flat gasket.

2. The pressing method for a spacer block for A-95 ceramic sintering according to claim 1, characterized in that, The outer diameter of the flat gasket is uniformly determined based on the outer diameter dimensions of products with similar specifications.

3. A pressing method for a spacer block for A-95 ceramic sintering according to claim 1, characterized in that, The diameter of the central hole in the flat gasket is 30mm.

4. A method for machining a spacer block for A-95 ceramic sintering, characterized in that, The method for machining a flat gasket produced by any one of claims 1-3 includes the following steps: M1. Transfer and position the flat pad onto the worktable of the machining system; M2. Pneumatically press the positioned flat pad and rotate it together with the worktable; M3. The rotating flat plate washer is machined by a cutting tool controlled by the program. First, its outer diameter is machined, and then a step structure is machined on it using a forming tool. The step structure is used to match the inner diameter of the ceramic blank to be sintered in order to limit shrinkage.

5. A method for manufacturing a spacer block for A-95 ceramic sintering according to claim 4, characterized in that, During the M1 process, a robot picks up and places a flat plate pad. The center of the workbench is equipped with an inner diameter pneumatic three-jaw chuck. By driving the inner diameter pneumatic three-jaw chuck to open the middle hole of the flat plate pad, the flat plate pad is repositioned.

6. A method for manufacturing a spacer block for A-95 ceramic sintering according to claim 5, characterized in that, During the M2 process, a clamping cylinder located directly above the center of the workbench drives a nylon block to press down, thereby fixing the flat plate pad after secondary positioning.

7. A method for manufacturing a spacer block for A-95 ceramic sintering according to claim 4, characterized in that, It also includes M4. After the machine is completed, high-pressure air pipes are used to blow away the floating dust on the surface of the pad, and dust is collected using a dust suction pipe.

8. A method for manufacturing a spacer block for A-95 ceramic sintering according to claim 7, characterized in that, It also includes the M5, where scrap material generated during the turning process is collected through a recycling system located at the bottom of the lathe.

9. A method for manufacturing a spacer block for A-95 ceramic sintering according to claim 4, characterized in that, It also includes an automatic size detection step: after the set quantity is machined, a laser measuring instrument is used to automatically detect the step diameter and platform height of the machined pads.

10. A method for machining a spacer block for A-95 ceramic sintering according to claim 9, characterized in that, In the automatic size detection step, when the detected size exceeds the preset size deviation area, the equipment alarms and suspends processing.

Images