A precision stamping method for the bent portion of a measuring switch front baffle

Abstract

This application relates to the field of switch component manufacturing technology, specifically to a precision stamping method for measuring the bending portion of a switch front baffle. This method offers advantages such as improving the dimensional accuracy of the bending portion of the front baffle, reducing the impact of springback, and ensuring consistent arc distance, thereby enhancing the long-term reliability and performance stability of the switch component. By precisely controlling the stamping speed, stamping pressure, holding time, die clearance, and springback compensation, this invention achieves bending angle tolerance control within the range of ±0.2° to ±0.3°, thus improving the dimensional accuracy of the bending portion of the front baffle, reducing the impact of springback, and ensuring consistent arc distance, thereby enhancing the long-term reliability and performance stability of the switch component.

Description

Technical Field

[0001] This application relates to the field of switch element manufacturing technology, and more specifically, to a precision stamping method for measuring the bending portion of a switch front baffle. Background Technology

[0002] In the structural design of measuring switches, the front baffle, as a core component, plays a crucial role in arc suppression and surge current attenuation through its curved section. In existing technologies, the front baffle is typically made of ordinary copper and formed into a curved structure using traditional bending processes. However, ordinary copper has significant drawbacks in terms of material properties: pure copper, despite its high conductivity, lacks sufficient mechanical strength and is prone to springback and permanent deformation after stamping and bending, resulting in poor dimensional stability. If high-strength brass is used, the conductivity decreases drastically, failing to meet the stringent conductivity requirements of switching components. Furthermore, ordinary copper has weak resistance to arc corrosion; under repeated short-circuit arc impacts, it easily develops oxide layers and ablation pits on its surface, causing a continuous increase in contact resistance. Its thermal stability is also unsatisfactory, with a low softening temperature range, making it prone to softening under the localized high temperatures caused by large short-circuit currents, further exacerbating the risk of dimensional changes.

[0003] At the forming process level, traditional bending technology is constrained by factors such as material batch fluctuations, uncontrollable springback, and mold wear. The bending angle tolerance is generally maintained within a wide range of ±0.5° to ±1°, while the bending radius tolerance reaches ±0.2mm to ±0.5mm. This dimensional deviation directly leads to poor consistency in the arc distance between the front and rear baffles, resulting in significant fluctuations in arc suppression effects within the same batch of products. Furthermore, the residual stress generated during bending is easily released under subsequent thermal cycling or vibration conditions, causing micro-deformation of the structure. Wrinkles and scratches often appear on the inner surface of the bend, affecting not only conductivity but also altering the surface state at the time of arc generation. These material and process problems are intertwined; insufficient conductivity causes abnormal heating in the bent section, which in turn accelerates material softening and dimensional drift, ultimately severely damaging the long-term reliability and performance stability of the switching element.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] (a) Technical problems to be solved The purpose of this application is to provide a precision stamping forming method for measuring the bending portion of a switch front baffle, which has the advantages of improving the dimensional accuracy of the bending portion of the front baffle, reducing the impact of springback, and ensuring the consistency of the arc distance, thereby improving the long-term reliability and performance stability of the switching element.

[0006] (II) Technical Solution This application provides a precision stamping method for the bent portion of a measuring switch front baffle, the technical solution of which is as follows: A precision stamping forming method for the curved portion of a measuring switch front baffle includes the following steps performed sequentially: providing a metal blank; forming the blank using a precision stamping process to form a front baffle with a first curved portion and a second curved portion; controlling the stamping speed, stamping pressure, holding time, and die clearance during the forming process, and adjusting the actual bending angle to the target bending angle through springback compensation, wherein the compensation amount of springback compensation is 2% to 5% of the target bending angle; and performing precision inspection on the formed front baffle to ensure that the bending angle tolerance of the first and second curved portions is controlled within the range of ±0.2° to ±0.3°.

[0007] Furthermore, this application also proposes a curved portion of a measuring switch front baffle, which is manufactured using the aforementioned precision stamping forming method. It includes a first curved portion and a second curved portion. The first curved portion has a bending angle of 30°~60° and a bending radius of 2~4mm. The second curved portion has a bending angle of 60°~120° and a bending radius of 2~4mm. The surface roughness Ra of the curved portion of the front baffle is ≤1.6μm.

[0008] (III) Beneficial Effects Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves bending angle tolerance control within the range of ±0.2° to ±0.3° by precisely controlling the stamping speed, stamping pressure, holding time, die clearance, and springback compensation. This has the advantages of improving the dimensional accuracy of the front baffle bending part, reducing the impact of springback, and ensuring the consistency of arc distance, thereby enhancing the long-term reliability and performance stability of the switching element. Attached Figure Description

[0009] 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. Obviously, 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.

[0010] Figure 1 A flowchart illustrating the precision stamping process for measuring the bent portion of the switch front baffle. Figure 2 This is a three-dimensional structural diagram of the front baffle of the measuring switch.

[0011] 10. Front baffle, 101. First curved portion, 102. Second curved portion. Detailed Implementation

[0012] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0013] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0014] Traditionally, the curved section of the front baffle of a measuring switch is manufactured using ordinary copper material and conventional bending processes. This results in a trade-off between conductivity and strength, and insufficient resistance to arc corrosion and thermal stability. Furthermore, the conventional bending process suffers from poor dimensional consistency, unstable arc distance, high residual stress, and inconsistent surface quality. These material and process problems combine to severely impact the long-term stability of the arc suppression and surge current attenuation effects of the curved section of the measuring switch's front baffle.

[0015] In this regard, refer to Figures 1-2 This application proposes a precision stamping forming method for measuring the bending portion of a switch front baffle, comprising the following steps performed sequentially: S1. Provide metal material blanks; S2. The blank is formed by precision stamping process to form a front baffle with a first curved part and a second curved part; S3. During the forming process, control the stamping speed, stamping pressure, holding time, and die clearance, and adjust the actual bending angle to the target bending angle through springback compensation. The compensation amount of the springback compensation is 2% to 5% of the target bending angle. S4. Perform precision inspection on the formed front baffle to ensure that the bending angle tolerance of the first and second curved parts is controlled within the range of ±0.2°~±0.3°.

[0016] For ease of understanding, the following explains some key terms in this embodiment: Metal blank: refers to the original metal sheet or strip used for stamping, whose material, thickness, surface condition, etc. must meet the requirements of subsequent precision stamping processes.

[0017] Precision stamping is a forming technology that uses precision molds and high-precision stamping equipment to plastically deform metal materials to obtain high-precision parts with high surface quality. Its key feature is the precise control of various parameters during the stamping process.

[0018] The first and second curved sections are important structures that constitute the front baffle. They achieve arc suppression and surge current attenuation through specific bending angles and radii.

[0019] Front baffle: An important component in measuring switches, the geometric accuracy of its curved portion directly affects the performance and reliability of the switch.

[0020] Stamping speed: refers to the speed at which the punch or blank holder descends during the stamping process. Its control has a significant impact on the material deformation behavior and springback.

[0021] Stamping pressure: refers to the force applied to the die by stamping equipment, which is used to drive the deformation of the material. Its precise control is the key to achieving precision forming.

[0022] Holding time: refers to the time that the die maintains pressure in the closed state after stamping, which helps to reduce springback and stabilize part dimensions.

[0023] Die clearance: refers to the distance between the punch and die in a stamping die, and its size directly affects the shearing quality and dimensional accuracy of the stamped parts.

[0024] Springback compensation: refers to taking into account the springback phenomenon of materials in advance when designing molds or adjusting process parameters, and making the actual bending angle of the final part reach the target value by increasing or decreasing the bending angle.

[0025] Target bending angle: refers to the ideal bending angle required for the design of the front bumper, which is the final geometric parameter that needs to be achieved in precision stamping.

[0026] Precision inspection: refers to the measurement and evaluation of the dimensions, angles, surface quality, etc. of the formed front baffle to ensure that it meets the design requirements and tolerance range.

[0027] Bending angle tolerance: refers to the maximum allowable deviation range between the actual bending angle and the target bending angle, and is an important indicator for measuring forming accuracy.

[0028] The precision stamping method of this application first provides a metal blank. This blank can be a standard-sized metal sheet or strip, which is then obtained through shearing or pre-punching. The material of the blank can be selected from various metal alloys such as copper, aluminum, and steel, according to the design requirements of the front baffle, and its thickness, hardness, and other performance parameters can be determined.

[0029] Subsequently, the blank is formed using a precision stamping process to create a front baffle with a first curved portion and a second curved portion. This forming process can be performed in a single-stage stamping using a single-station die, or in stages using a multi-station die. The die material can be cemented carbide or high-speed steel, and its structural design ensures that the first and second curved portions can be precisely formed.

[0030] During the forming process, the stamping speed, stamping pressure, holding time, and die clearance are controlled. The stamping speed can be adjusted via the hydraulic system or servo motor of the stamping equipment, for example, by setting it to a constant speed or segmented speed variation. The stamping pressure is controlled by adjusting the pressure of the hydraulic cylinder or the stroke of the mechanical press. The holding time is set by the control system of the stamping equipment. The die clearance is determined by the design and manufacturing precision of the die, or by fine-tuning using an adjustable die.

[0031] Furthermore, springback compensation adjusts the actual bending angle to the target bending angle, with the compensation amount being 2% to 5% of the target bending angle. Springback compensation can be achieved by pre-designing the bending angle to be larger than the target angle during die design to counteract material springback. For example, if the target bending angle is 90 degrees, the die bending angle can be designed to be 92 to 94.5 degrees. Another approach is to dynamically compensate for springback during the stamping process by adjusting the stamping depth or applying reverse pressure.

[0032] Finally, the formed front baffle is subjected to precision inspection to ensure that the bending angle tolerances of the first and second curved sections are controlled within the range of ±0.2° to ±0.3°. Precision inspection can be performed manually using tools such as angle gauges and protractors, or through non-contact measurement using automated equipment such as optical measuring devices and coordinate measuring machines. The measurement results are compared with the design tolerances to determine whether the product is qualified.

[0033] The precision stamping method of this application effectively overcomes the shortcomings of traditional bending processes in terms of dimensional consistency, residual stress, and surface quality by precisely controlling key parameters during the stamping process and introducing a springback compensation mechanism. This ensures that the bent portion of the measuring switch's front baffle has a high-precision bending angle and stable geometric dimensions, thereby guaranteeing the long-term reliability of arc suppression and surge current attenuation effects and significantly improving the overall performance of the measuring switch.

[0034] In some embodiments described above in this application, a method for precisely forming the curved portion of the front baffle is proposed by controlling the stamping speed, stamping pressure, holding time, and die clearance, and combining springback compensation. However, in actual operation, if the equipment performing the precision stamping process is not precise enough, it is difficult to ensure the accurate implementation of various control parameters, which may affect the accuracy and consistency of the final formed part and make it difficult to meet the high precision requirements of the measuring switch front baffle.

[0035] In this regard, this application further proposes that the above-mentioned precision stamping process is performed by precision stamping equipment, wherein the pressure control accuracy of the precision stamping equipment is within ±1%, and the position control accuracy is within ±0.01mm.

[0036] Specifically, the precision stamping equipment is a type of machinery specifically designed for high-precision stamping operations. It typically features a high-rigidity structure, an advanced control system, and extremely small mechanical clearances to ensure the precise application of various parameters during the stamping process. The purpose of using this equipment is to apply the key process parameters set in the aforementioned method, such as stamping speed, stamping pressure, holding time, and die clearance, to the metal blank with extremely high accuracy, thereby achieving precision forming of the curved portion of the front baffle.

[0037] The precision stamping equipment features a pressure control accuracy within ±1%, meaning it can precisely control the applied stamping pressure within ±1% of the target pressure. For example, if the target stamping pressure is 100kN, the actual applied pressure will be between 99kN and 101kN. This high-precision pressure control is crucial for ensuring uniform material flow and consistent plastic deformation during the deformation process. It directly affects the formation of the bending angle and the amount of springback, thereby guaranteeing the geometric accuracy and mechanical property stability of the formed part. Achieving this accuracy typically relies on high-resolution pressure sensors and closed-loop feedback control systems, which can monitor the pressure in real time and fine-tune the hydraulic or servo actuators.

[0038] Meanwhile, the position control accuracy of the precision stamping equipment is within ±0.01mm, meaning that the positioning accuracy of the punch or die in the vertical direction can reach an extremely high level of ±0.01mm. For example, when stamping to the bottom dead center, the deviation between the actual position reached by the punch and the preset target position does not exceed 0.01mm. This micron-level positioning accuracy plays a decisive role in accurately controlling the bending depth, die clearance, and the final bending radius and angle. In the precision stamping process, even a small positional deviation can lead to significant changes in the bending angle or local stress concentration, thereby affecting the overall accuracy and function of the front stop. High-precision position control is usually achieved by equipping high-precision linear encoders or rotary encoders, combined with advanced servo motor drives and control algorithms. These technologies can effectively compensate for the influence of factors such as mechanical deformation and thermal expansion on position accuracy.

[0039] By employing precision stamping equipment with high pressure and position control accuracy to execute the precision stamping process, the aforementioned technical solutions ensure the accurate and stable implementation of all process parameters set in the method. High-precision pressure control guarantees a high degree of consistency in the mechanical conditions acting on the material during the forming process, effectively reducing uneven material deformation and springback differences caused by pressure fluctuations. High-precision position control ensures the die accurately shapes the bending depth and geometry of the material, allowing the bending angles of the first and second bends to precisely meet design requirements, with the bending angle tolerance strictly controlled within ±0.2° to ±0.3°. This significantly improves the forming accuracy and batch consistency of the bending portion of the measuring switch's front baffle, effectively solving the problem of insufficient equipment precision leading to inaccurate execution of technical parameters, thus meeting the stringent high-precision requirements of the measuring switch components.

[0040] In some embodiments described above, a method is proposed for forming a metal blank using a precision stamping process to obtain a front baffle with a specific curved portion. However, in the actual forming process, if key process parameters such as stamping speed, stamping pressure, and holding time are not precisely and reasonably limited, it may lead to uneven material deformation and difficulty in accurately controlling the springback, thereby affecting the forming accuracy and consistency of the curved portion of the front baffle and making it difficult to meet strict tolerance requirements.

[0041] In this regard, this application further proposes to set the stamping speed to 10~50mm / s, the stamping pressure to 50~200kN, and the holding time to 0.5~2s.

[0042] Specifically, stamping speed refers to the downward speed of the punch during the stamping process, which has a significant impact on the material's deformation behavior, strain rate, and internal stress distribution. In precision stamping, excessively high stamping speeds may lead to localized overheating, tearing, or increased springback of the material, while excessively low speeds may reduce production efficiency and increase friction between the die and the material. Controlling the stamping speed within the range of 10~50 mm / s ensures that the material undergoes plastic deformation at an appropriate strain rate, which is beneficial for uniform material flow and forming, while avoiding the negative effects of excessively high or low speeds. Stamping pressure is the force applied to the die by the stamping equipment to cause plastic deformation of the material. Sufficient stamping pressure is key to ensuring that the material completely fills the die cavity and forms a clear curved profile. However, excessive pressure may lead to accelerated die wear, excessive material deformation, or even breakage, while insufficient pressure may result in incomplete forming and dimensional defects. Setting the stamping pressure within the range of 50~200 kN provides sufficient and stable force for the precision forming of the front baffle bend, effectively overcoming the material's deformation resistance and ensuring the shape and dimensional accuracy of the bend. Holding time refers to the time the punch remains at or near the bottom dead center (BDC) and maintains pressure after the stamping process reaches its final position. The holding time is crucial for stabilizing the final shape of the material, reducing springback, and eliminating internal residual stress. An appropriate holding time allows for a degree of relaxation and redistribution of internal stresses, resulting in a more stable shape and higher dimensional accuracy in the formed part. Controlling the holding time within the range of 0.5 to 2 seconds provides sufficient time for stress relaxation and shape solidification, effectively suppressing springback and improving the stability of bending angles.

[0043] By limiting the stamping speed, stamping pressure, and holding time in the precision stamping process to a specific optimized range, the forming accuracy and consistency of the front baffle bending section can be significantly improved. Precisely controlled stamping speed ensures uniform deformation of the material at the optimal strain rate, avoiding material damage and unnecessary stress concentration; appropriate stamping pressure ensures that the material can fully fill the mold cavity, forming a clear and precise bending profile; and a reasonable holding time effectively promotes the relaxation of internal stress in the material, significantly reducing the elastic springback after forming and stabilizing the bending angle. The synergistic optimization of these parameters allows the actual bending angle to be more accurately adjusted to the target bending angle through springback compensation, ultimately strictly controlling the bending angle tolerance of the first and second bending sections within the range of ±0.2° to ±0.3°. This effectively solves the problem of forming accuracy and consistency caused by unclear or unreasonable process parameters, ensuring high-quality manufacturing of the front baffle bending section of the measurement switch.

[0044] In some embodiments described above, a method is proposed to precisely form a front baffle with a first and a second curved portion by controlling the stamping speed, stamping pressure, holding time, and die clearance, and by combining springback compensation to adjust the actual bending angle to the target bending angle, thereby controlling the bending angle tolerance of the first and second curved portions within the range of ±0.2° to ±0.3°. However, in actual production, if the range of stamping speed and holding time is set too wide, for example, a stamping speed of 10 to 50 mm / s and a holding time of 0.5 to 2 s, the plastic flow state of the metal blank in the die cavity may become unstable, which in turn affects the internal stress distribution and the consistency of springback in the formed part. This makes it difficult to precisely control the bending angle of the first and second curved portions of the final formed front baffle within the strict tolerance range, thus affecting the accuracy and consistency of the product.

[0045] In this regard, this application further optimizes the stamping speed and holding time in the forming process, specifically: the stamping speed is 20~30mm / s, and the holding time is 0.5~1.5s.

[0046] In stamping, stamping speed refers to the downward speed of the punch during the stamping process. In precision stamping, stamping speed significantly affects the material's deformation behavior, strain rate, friction state, and the accuracy and surface quality of the final formed part. Limiting the stamping speed to a narrow range of 20-30 mm / s helps ensure a more uniform strain distribution during material deformation, reducing material tearing due to excessive speed or low forming efficiency due to insufficient speed. This speed range can be achieved through the servo control system of the precision stamping equipment. For example, by adjusting the relationship between punch displacement and time through preset motion curves or real-time feedback, the punch can be stably maintained within this speed range during the plastic deformation stage. Alternatively, the stamping speed can also be precisely controlled by adjusting the flow rate of the hydraulic system or the gear ratio of the mechanical transmission system.

[0047] Holding time refers to the duration of continuous pressure applied to the material by the punch after it reaches the bottom dead center, while the die is closed. The purpose of holding time is to promote the redistribution of internal stress in the material after plastic deformation, reducing elastic recovery and thus more effectively controlling springback, thereby improving the dimensional accuracy and shape stability of the formed parts. Limiting the holding time to the range of 0.5~1.5s provides sufficient but not excessive time for the relaxation and rearrangement of internal stresses. Too short a holding time may lead to insufficient springback control, while too long a holding time may reduce production efficiency and offer limited improvement in accuracy. This time range can be precisely set through the control system of precision stamping equipment, for example, by using a PLC (Programmable Logic Controller) or a dedicated controller to start a timer after the punch reaches a preset position and execute a die opening command after the set time is reached.

[0048] By limiting the stamping speed and holding time to a more optimized narrow range through the above technical solutions, the plastic flow behavior and stress state of the metal blank during the molding process can be significantly improved. Specifically, a stamping speed of 20~30mm / s helps to avoid local overheating or stress concentration during high-speed deformation, while avoiding inefficiency and excessive friction during low-speed deformation, thus ensuring the uniformity and stability of material deformation. A holding time of 0.5~1.5s allows for more precise control of the material's solidification and stress release process within the mold cavity, effectively suppressing elastic rebound, so that the actual bending angles of the first and second curved parts of the front baffle after demolding are closer to the target bending angle. This refined parameter control, combined with a springback compensation mechanism, can more stably control the bending angle tolerance within a strict range of ±0.2°~±0.3°, thereby significantly improving the forming accuracy and product consistency of the curved part of the measuring switch front baffle and reducing the scrap rate.

[0049] In some embodiments described above in this application, although the stamping speed and holding time in the precision stamping forming method are limited to a range in order to improve the forming accuracy, for certain specific materials or front baffles with complex shapes, even within these limited ranges, small fluctuations in the stamping process may still cause the dimensional consistency, surface quality, or internal stress distribution of the formed parts to fail to reach the optimal state, thereby affecting the performance and reliability of the final product.

[0050] In response, this application further proposes setting the stamping speed to 25 mm / s and the holding time to 1 s.

[0051] A stamping speed of 25 mm / s refers to the downward speed of the punch during the forming process of a metal blank. The selection of this speed is crucial for controlling the plastic deformation behavior of the material. Setting the stamping speed to 25 mm / s allows sufficient time for plastic flow during deformation, preventing localized stress concentration, tearing, or over-hardening caused by excessively rapid impact, while also ensuring production efficiency. This speed can be precisely adjusted and maintained through the servo control system or hydraulic system of the precision stamping equipment, ensuring the punch remains stable throughout the entire stamping stroke.

[0052] The holding time of 1 second refers to the time during which the punch maintains a certain pressure after reaching the bottom dead center while the die is closed. The holding time is crucial for ensuring sufficient material shaping and reducing springback. A holding time of 1 second allows the material to undergo sufficient plastic deformation and stress relaxation within the die cavity, promoting the rearrangement of internal grains, effectively suppressing springback, and helping to eliminate or reduce residual stress within the formed part. Precise control of this time parameter is typically achieved through the control system of the stamping equipment, which sets and monitors the hydraulic or mechanical pressure holding time.

[0053] By precisely setting the stamping speed to 25 mm / s using the above technical solution, the material can undergo plastic flow more smoothly and uniformly during deformation, effectively avoiding material defects such as surface scratches, internal micro-cracks, or uneven deformation that may be caused by excessively fast or slow speeds. Simultaneously, setting the holding time to 1 second ensures sufficient time for plastic shaping and stress release within the mold cavity, significantly reducing springback after forming and optimizing the stress distribution within the front baffle. This precise parameter control allows the bending angle tolerances of the first and second bends of the front baffle to be more stably controlled within the range of ±0.2° to ±0.3°, further improving the forming accuracy, dimensional consistency, and reliability of the bending portion of the measuring switch's front baffle, enabling it to better meet the stringent performance requirements of high-precision measuring switches.

[0054] In some embodiments described above, a precision stamping process is proposed to form metal blanks, controlling the stamping speed, stamping pressure, holding time, and die clearance during the forming process. Springback compensation is used to adjust the actual bending angle to the target bending angle, aiming to control the bending angle tolerance of the first and second bending portions of the front baffle within the range of ±0.2° to ±0.3°. However, in actual operation, if key die parameters such as die clearance, punch radius, and die radius are not precisely optimized, uneven deformation, stress concentration, excessive thinning, or even cracking of the material may occur during stamping. This makes it difficult to consistently meet the strict bending angle tolerance requirements, affecting the forming quality and consistency of the front baffle.

[0055] In this regard, this application further proposes that the mold clearance is 6% to 10% of the material thickness, the punch fillet radius is 0.8 to 1.2 times the material thickness, and the die fillet radius is 1.5 to 2.0 times the material thickness; the mold clearance is preferably 8% of the material thickness, the punch fillet radius is preferably 1.0 times the material thickness, and the die fillet radius is preferably 1.8 times the material thickness.

[0056] Specifically, die clearance refers to the radial distance between the punch and the die. In precision stamping, setting the die clearance within the range of 6% to 10% of the material thickness ensures that the material receives appropriate constraint and flow space within the die cavity. If the die clearance is too small, the material will be subjected to excessive compression during stamping, potentially leading to over-hardening, surface scratches, or even punch jamming. If the die clearance is too large, it may cause uneven deformation, wrinkling, or increased springback in the bending area, thus affecting forming accuracy. Therefore, a die clearance of 8% of the material thickness is preferred. This aims to further optimize the stress state and deformation behavior of the material during stamping through more precise parameter settings, ensuring sufficient plastic flow while minimizing excessive stretching or compression, thereby achieving more stable forming results and higher dimensional accuracy.

[0057] The punch fillet radius refers to the radius of the arc transition area where the punch contacts the material. Controlling the punch fillet radius to 0.8–1.2 times the material thickness helps guide the material smoothly into the bending area, disperses stress, and reduces local stress concentration, thereby improving forming quality and preventing material damage. A smaller punch fillet radius may lead to excessive stress concentration at the bending point, easily causing cracking or excessive thinning; while an excessively large punch fillet radius may result in poor material adhesion in the bending area, increasing springback and potentially forming irregular bending shapes. Therefore, a punch fillet radius of 1.0 times the material thickness is preferred, aiming to provide a more ideal transition point at the bending start, resulting in a more uniform stress distribution when the material enters the bending area, effectively reducing local stress concentration, thereby further reducing the risk of material cracking or excessive thinning and improving the reliability of bending forming.

[0058] The die fillet radius refers to the radius of the arc transition area at the entrance of the die cavity. Setting the die fillet radius to 1.5 to 2.0 times the material thickness optimizes material flow and deformation within the die, ensuring uniform plastic deformation in the bending area and thus obtaining high-precision bent parts. This parameter works synergistically with the punch fillet radius to jointly determine the stress state and deformation path of the material during bending. If the die fillet radius is too small, the material is easily overstretched on the outer side of the bend, potentially leading to breakage; if it is too large, it may result in poor material adherence to the mold in the bending area, affecting the precise control of the bending angle. Based on this, a die fillet radius of 1.8 times the material thickness is preferred, aiming to further optimize material flow and adherence within the die cavity, reduce frictional resistance, and ensure uniform and controlled tensile deformation of the material at the outer edge of the bend, thereby effectively avoiding material defects during the forming process while ensuring bending accuracy.

[0059] By precisely setting and optimizing the die clearance, punch fillet radius, and die fillet radius, the plastic flow and stress distribution of the metal blank during precision stamping can be effectively controlled. A reasonable die clearance ensures proper constraint of the material within the die cavity, preventing excessive extrusion or wrinkling. Optimized punch and die fillet radii guide the material through smooth bending deformation, dispersing stress concentration and significantly reducing the risk of material cracking, excessive thinning, or unstable springback. The synergistic effect of these parameters allows the first and second curved sections of the front baffle to be formed with higher precision and consistency, making it easier to control the bending angle tolerance within a strict range of ±0.2° to ±0.3°, significantly improving the overall quality and reliability of the measurement switch front baffle.

[0060] In some embodiments described above in this application, springback compensation is proposed to adjust the actual bending angle to the target bending angle to ensure the accuracy of the front baffle bending portion. However, in actual precision stamping processes, the springback phenomenon of materials is complex and difficult to predict accurately. Simply setting a compensation amount may not be sufficient to effectively address the differences in springback caused by factors such as different material batches, ambient temperature, or mold wear, thereby affecting the accuracy and stability of the final bending angle.

[0061] In response, this application further proposes that the springback compensation is achieved through mold pre-deformation, with the mold pre-deformation amount being 1% to 3% of the target bending angle; or the springback compensation is achieved through multi-station progressive forming, with the deformation amount at each station increasing until the final station reaches the target bending angle.

[0062] Specifically, when springback compensation is achieved through die pre-deformation, this is a compensation strategy that takes the material springback effect into account during the die design and manufacturing stages. When designing a stamping die, based on parameters such as the mechanical properties of the metal material, sheet thickness, bending radius, and target bending angle, a die angle opposite to the material springback direction is pre-determined through theoretical calculations, finite element analysis (FEA) simulations, or preliminary die trial data. For example, if the material springs back outward after bending, the die bending angle is designed to be slightly smaller than the target angle, ensuring the material accurately reaches the target bending angle after springback. A die pre-deformation amount of 1% to 3% of the target bending angle means that the die forming angle will be pre-adjusted by 1% to 3% compared to the final target angle to counteract springback. This method places springback control forward into the die manufacturing stage; once the die is manufactured, its compensation effect is relatively stable.

[0063] Alternatively, the springback compensation can be achieved through multi-station progressive forming. Multi-station progressive forming is a method that gradually completes a complex bending shape through multiple consecutive stamping stations. In this method, the bending process of the front baffle is broken down into several small steps, with each station only completing a portion of the plastic deformation. For example, the first station may perform preliminary pre-bending, the second station further increases the degree of bending, until the last station completes the final precise forming. The shape and size of the mold at each station are carefully designed to ensure that the amount of material deformation increases at each stage and that the stress distribution is optimized. Through this progressive deformation, the stress concentration and springback uncertainty caused by a single large deformation can be effectively reduced, allowing the material to more stably reach the target bending angle at the final station, thereby improving forming accuracy.

[0064] Through the above technical solutions, this application provides two specific and efficient springback compensation mechanisms, effectively solving the problem of springback control in precision stamping. The first method uses pre-deformation of the mold, integrating springback compensation into the mold design and manufacturing process. This eliminates the need for frequent adjustments to process parameters during stamping, improving production stability and efficiency, and ensuring the consistency of the front baffle bending angle in mass production. The second method uses multi-station progressive forming, which decomposes the complex bending process into multiple controllable steps. Each station gradually accumulates deformation, effectively managing internal material stress and significantly reducing the unpredictability of springback, making it particularly suitable for front baffles with extremely high bending accuracy requirements. Both methods ensure that the bending angle tolerance of the first and second bending portions of the front baffle is stably controlled within ±0.2° to ±0.3°, thereby significantly improving the manufacturing accuracy and product quality of the measuring switch front baffle and meeting the stringent requirements of high-precision measuring switches.

[0065] In some embodiments described above in this application, a method is proposed for forming a metal blank using a precision stamping process to obtain a front baffle with a specific curved portion. However, during the precision stamping process, the metal material may generate significant internal stress during plastic deformation. Simultaneously, friction between the die and the material may cause surface damage. These factors can all affect the dimensional accuracy, surface quality, and long-term performance of the front baffle.

[0066] To address this, this application further proposes using a copper alloy-specific stamping oil for lubrication in the precision stamping process, and adding a stress-relief treatment step after forming. Specifically, the precision stamping process uses a copper alloy-specific stamping oil for lubrication, with the preferred viscosity of the oil being 10~50 mm² / s and the preferred application amount being 3~8 g / m². The copper alloy-specific stamping oil is a lubricant specially formulated for the characteristics of copper alloy materials. Its unique formula effectively reduces the coefficient of friction between the die and the metal blank during stamping, reducing heat accumulation and die wear caused by friction. By precisely controlling the viscosity of the lubricant within the range of 10~50 mm² / s, a stable and sufficiently load-bearing lubricating film can be formed under high-speed stamping conditions. This film effectively isolates the die and the workpiece, preventing metal adhesion, and ensures smooth material flow within the die cavity. Simultaneously, controlling the application amount within the range of 3~8 g / m² achieves uniform and appropriate lubrication, avoiding surface damage due to insufficient lubrication and preventing subsequent cleaning difficulties or environmental pollution due to excessive lubrication.

[0067] In addition, the post-forming process includes a stress-relief treatment step. The preferred temperature for this stress-relief treatment is 150-200°C, the preferred holding time is 1-2 hours, and the preferred cooling method is furnace cooling. Stress relief treatment is a heat treatment process designed to eliminate or significantly reduce residual internal stress generated in metallic materials during cold working (such as precision stamping). Controlling the treatment temperature at 150-200°C, typically below the recrystallization temperature of copper alloys, allows for limited rearrangement of atoms within the material, thereby releasing internal stress without causing significant grain growth or material softening, thus maintaining its original mechanical properties. The holding time is set to 1-2 hours to ensure sufficient heat penetration into the front baffle, allowing the stress release process to proceed fully. Furnace cooling, where the workpiece is slowly cooled to room temperature in the furnace, effectively avoids the reintroduction of new thermal stress due to rapid cooling, thus ensuring the final effect of the stress-relief treatment.

[0068] By employing a copper alloy-specific stamping oil for lubrication in the precision stamping process, the above technical solutions effectively reduce the coefficient of friction between the die and the metal blank, minimizing heat and wear during stamping. This significantly improves the surface quality of the front baffle's curved portion, preventing scratches and burrs, and extending the die's lifespan. Simultaneously, precise control of the lubricant's viscosity and application amount ensures stable and uniform lubrication, further enhancing forming accuracy. Furthermore, a stress-relief treatment step is introduced after forming. By holding the baffle at a specific temperature and then cooling it in the furnace, residual stress generated within the metal material during precision stamping is effectively eliminated. This significantly improves the dimensional stability of the front baffle, reducing the risk of deformation or cracking during use and ensuring the reliability and precision of the curved portion during long-term operation. These combined measures result in a front baffle curved portion with not only excellent surface quality but also a more stable internal structure, higher precision, and greater reliability.

[0069] Example 1

[0070] This embodiment uses the preferred parameter combination of the precision stamping forming method of this application to manufacture the curved part of the front baffle of the measuring switch, which represents the best effect of the technical solution of this application.

[0071] In this embodiment, a chromium-zirconium-copper alloy (QCr0.5~1.0) is selected as the material. The material is in a solution-treated and aged state, with a thickness of 2.0 mm, a hardness of HV 130~145, a conductivity ≥75% IACS, a tensile strength ≥400 MPa, a yield strength ≥350 MPa, and an elastic modulus of 120~130 GPa. This chromium-zirconium-copper alloy possesses excellent conductivity (75%~85% IACS) and high strength (tensile strength 400~500 MPa), while also exhibiting good resistance to arc corrosion and thermal stability. This meets the dual requirements of the measuring switch for the conductivity and mechanical properties of the front baffle.

[0072] The stamping equipment uses a precision servo hydraulic press with a nominal pressure of 100~200 kN, pressure control accuracy within ±1%, position control accuracy within ±0.01mm, slide repeatability accuracy within ±0.005mm, and pressure sensor resolution of 0.1kN. The die material is cemented carbide YG20, with a die hardness of HRC 62~65, a die surface roughness Ra≤0.4μm, a die machining accuracy of ±0.01mm, and a die life ≥500,000 cycles.

[0073] The process parameters are set as follows: stamping speed is 25 mm / s, stamping pressure is approximately 57 kN, and holding time is 1.0 s. The die clearance is set to 8% of the material thickness, i.e., 0.16 mm; the punch fillet radius is 1.0 times the material thickness, i.e., 2.0 mm; and the die fillet radius is 1.8 times the material thickness, i.e., 3.6 mm. Springback compensation is achieved through die pre-deformation, with a compensation amount of 2%~3% of the target bending angle. The pre-deformation angle of the first bending section is 45.9° (target 45° + 2%), and the pre-deformation angle of the second bending section is 92.7° (target 90° + 3%).

[0074] Lubrication uses a special stamping oil for copper alloys (sulfurized fatty oil base), with a viscosity of 30 mm² / s (40℃) and an oil application rate of 5 g / m². After molding, stress relief treatment is performed, with a heating temperature of 180℃, a holding time of 1.5 hours, and furnace cooling.

[0075] In this embodiment, the target bending angle of the first bending portion is 45°, the bending radius is 3.0mm, and the bending segment length is 11.0mm; the target bending angle of the second bending portion is 90°, the bending radius is 3.0mm, and the bending segment length is 16.0mm.

[0076] The measurement results are shown in the table below (sample size n=100 pieces): First bending angle θ1 45.0° 44.72°~45.28° 45.02° 0.08° ±0.3° 100% qualified First bending radius R1 3.0mm 2.92~3.08mm 3.01mm 0.04mm ±0.15mm 100% qualified The length of the first curved section is L1 11.0mm 10.85~11.15mm 10.98mm 0.06mm ±0.2mm 100% qualified The angle of the second bend is θ2 90.0° 89.68°~90.32° 90.03° 0.09° ±0.3° 100% qualified The radius of the second bend is R2 3.0mm 2.91~3.09mm 3.02mm 0.05mm ±0.15mm 100% qualified The length of the second curved section is L2 16.0mm 15.82~16.18mm 15.97mm 0.07mm ±0.2mm 100% qualified Note: The above data are sample data. Actual parameters need to be optimized and adjusted based on specific materials, equipment status, and process verification results.

[0077] The performance indicators of this embodiment are as follows: the first bending angle tolerance reaches ±0.28° (3σ), the second bending angle tolerance reaches ±0.27° (3σ), the bending radius tolerance reaches ±0.12mm (3σ), the batch consistency of the angle Cpk reaches 1.25~1.35, which is significantly better than the requirement of ≥1.0; the surface roughness Ra is 0.6~1.2μm, which is better than the requirement of ≤1.6μm; the measured conductivity is 78~82%IACS, and the measured tensile strength is 420~450 MPa, both of which meet the requirements; the residual stress level is reduced by 40~50% compared with the traditional bending process.

[0078] Example 2 This embodiment studies the influence of stamping speed on the forming accuracy of the front baffle bending section by using three different sets of stamping speed parameters.

[0079] The three experimental groups used the same material (chromium-zirconium-copper alloy, 2.0 mm thick), the same holding time (1.0 s), and the same die parameters (die clearance 0.16 mm, punch radius 2.0 mm, die radius 3.6 mm), only varying the stamping speed. Experimental group A used a stamping speed of 15 mm / s, experimental group B used 25 mm / s, and experimental group C used 35 mm / s. Each group had a sample size of 50 pieces. The measuring equipment was a coordinate measuring machine, and the environmental conditions were room temperature 20 ± 2℃ and relative humidity 50 ± 10%.

[0080] The measurement results of experimental group A (15mm / s) are as follows: the mean angle θ1 of the first bending part is 44.98°, the standard deviation is 0.09°, the 3σ is ±0.27°, the maximum deviation is +0.18°, the minimum deviation is -0.15°, and the pass rate is 100%; the mean angle θ2 of the second bending part is 89.96°, the standard deviation is 0.10°, the 3σ is ±0.30°, the maximum deviation is +0.22°, the minimum deviation is -0.20°, and the pass rate is 100%; the surface roughness Ra ranges from 0.5 to 0.9 μm, with an average of 0.72 μm, and the surface defect rate is 0%; Cpk(θ1) is 1.18, and Cpk(θ2) is 1.08.

[0081] The measurement results of experimental group B (25 mm / s) are as follows: the mean angle θ1 of the first bending part is 45.02°, the standard deviation is 0.08°, the 3σ is ±0.24°, the maximum deviation is +0.12°, the minimum deviation is -0.10°, and the pass rate is 100%; the mean angle θ2 of the second bending part is 90.03°, the standard deviation is 0.09°, the 3σ is ±0.27°, the maximum deviation is +0.15°, the minimum deviation is -0.12°, and the pass rate is 100%; the surface roughness Ra ranges from 0.6 to 1.0 μm, with an average of 0.78 μm, and the surface defect rate is 0%; Cpk(θ1) is 1.32, and Cpk(θ2) is 1.28.

[0082] The measurement results of experimental group C (35mm / s) are as follows: the mean angle θ1 of the first bending part is 45.08°, the standard deviation is 0.11°, the 3σ is ±0.33°, the maximum deviation is +0.25°, the minimum deviation is -0.20°, and the pass rate is 98%; the mean angle θ2 of the second bending part is 90.15°, the standard deviation is 0.13°, the 3σ is ±0.39°, the maximum deviation is +0.35°, the minimum deviation is -0.28°, and the pass rate is 96%; the surface roughness Ra ranges from 0.7 to 1.3 μm, with an average of 0.95 μm and a surface defect rate of 2%; Cpk(θ1) is 0.95, and Cpk(θ2) is 0.85.

[0083] The above experimental results show that: when the stamping speed is too low (15 mm / s), although the accuracy is good, the production efficiency is low, and the long contact time between the die and the material may lead to increased friction; when the stamping speed is moderate (25 mm / s), the material flow is uniform, the deformation is stable, the springback is predictable, and compensation control is convenient, resulting in the highest overall accuracy and the largest Cpk value, which is the optimal balance point; when the stamping speed is too high (35 mm / s), the dynamic effect is enhanced, the deformation of strain rate sensitive materials is uneven, the springback is increased and the consistency is worse, and the accuracy decreases. This gradient experiment verifies the rationality of the preferred stamping speed range of 20~30 mm / s in this application.

[0084] Example 3

[0085] This embodiment studies the influence of holding time on the forming accuracy and springback control of the front baffle bending section using three different holding time parameters.

[0086] The three groups of experiments used the same material (chromium-zirconium-copper alloy, 2.0 mm thick), the same stamping speed (25 mm / s), and the same die parameters, only changing the holding time. Experimental group D used a holding time of 0.5 s, experimental group E used a holding time of 1.0 s, and experimental group F used a holding time of 1.5 s.

[0087] The measurement results of experimental group D (0.5s) are as follows: the mean angle θ1 of the first bending part is 45.08°, the standard deviation is 0.11°, the 3σ is ±0.33°, and the pass rate is 98%; the mean angle θ2 of the second bending part is 90.12°, the standard deviation is 0.12°, the 3σ is ±0.36°, and the pass rate is 97%; the average surface roughness Ra is 0.75μm; Cpk(θ1) is 0.98, and Cpk(θ2) is 0.92.

[0088] The measurement results of experimental group E (1.0s) are as follows: the mean angle θ1 of the first bending part is 45.02°, the standard deviation is 0.08°, the 3σ is ±0.24°, and the pass rate is 100%; the mean angle θ2 of the second bending part is 90.03°, the standard deviation is 0.09°, the 3σ is ±0.27°, and the pass rate is 100%; the average surface roughness Ra is 0.78μm; Cpk(θ1) is 1.32, and Cpk(θ2) is 1.28.

[0089] The measurement results of experimental group F (1.5s) are as follows: the mean angle θ1 of the first bending part is 44.99°, the standard deviation is 0.08°, the 3σ is ±0.24°, and the pass rate is 100%; the mean angle θ2 of the second bending part is 90.02°, the standard deviation is 0.09°, the 3σ is ±0.27°, and the pass rate is 100%; the average surface roughness Ra is 0.80μm; Cpk(θ1) is 1.30, and Cpk(θ2) is 1.26.

[0090] The experimental results show that when the holding time is too short (0.5s), the holding pressure is insufficient, elastic recovery is obvious, the rebound is increased, and the accuracy is slightly lower than the optimal value. When the holding time is moderate (1.0s), the internal stress of the material is fully relaxed, the elastic strain is effectively converted into plastic strain, the rebound is effectively suppressed, and the accuracy reaches the best. When the holding time is long (1.5s), the accuracy is similar to that of 1.0s, but the production efficiency is reduced. The stress relaxation of the material usually shows a pattern of rapid relaxation followed by slow relaxation. Most of the relaxation occurs within 0.5 to 1.0 seconds after the start of the holding time, and the relaxation increment is very small after 1.5 seconds. This gradient experiment verifies the rationality of the preferred holding time range of 0.5 to 1.5s in this application.

[0091] Example 4

[0092] This embodiment studies the influence of mold clearance on the forming accuracy of the front baffle bending section by using three different sets of mold clearance parameters.

[0093] The three groups of experiments used the same material (chromium-zirconium-copper alloy, 2.0 mm thick), the same stamping speed (25 mm / s), and the same holding time (1.0 s), only changing the die clearance. Experimental group G used a die clearance of 6% of the material thickness (0.12 mm), experimental group H used a die clearance of 8% of the material thickness (0.16 mm), and experimental group I used a die clearance of 10% of the material thickness (0.20 mm).

[0094] The measurement results of experimental group G (6% material thickness) are as follows: the mean angle θ1 of the first bending part is 44.96°, the standard deviation is 0.10°, the 3σ is ±0.30°, and the pass rate is 100%; the mean angle θ2 of the second bending part is 89.98°, the standard deviation is 0.11°, the 3σ is ±0.33°, and the pass rate is 99%; the average surface roughness Ra is 0.68μm, and 2% of the surface has slight scratches; Cpk(θ1) is 1.08, and Cpk(θ2) is 1.02.

[0095] The measurement results of experimental group H (8% material thickness) are as follows: the mean angle θ1 of the first bending part is 45.02°, the standard deviation is 0.08°, the 3σ is ±0.24°, and the pass rate is 100%; the mean angle θ2 of the second bending part is 90.03°, the standard deviation is 0.09°, the 3σ is ±0.27°, and the pass rate is 100%; the average surface roughness Ra is 0.78μm, and there are no surface defects; Cpk(θ1) is 1.32, and Cpk(θ2) is 1.28.

[0096] The measurement results of Experimental Group I (10% material thickness) are as follows: the mean angle θ1 of the first bending part is 45.10°, the standard deviation is 0.10°, the 3σ is ±0.30°, and the pass rate is 99%; the mean angle θ2 of the second bending part is 90.18°, the standard deviation is 0.11°, the 3σ is ±0.33°, and the pass rate is 98%; the average surface roughness Ra is 0.92μm; Cpk(θ1) is 1.05, and Cpk(θ2) is 0.98.

[0097] The above experimental results show that: when the mold clearance is too small (6% of material thickness), the material is subjected to excessive compression and scraping when passing through the gap, which may lead to surface scratches and adhesion, making demolding difficult; when the mold clearance is moderate (8% of material thickness), the material obtains appropriate constraint and flow space within the mold cavity, ensuring uniform plastic deformation in the bending area, controllable springback, and optimal precision; when the mold clearance is too large (10% of material thickness), the material lacks sufficient constraint during bending, which may lead to reduced bending angle accuracy and increased springback. This gradient experiment verifies the rationality of the preferred mold clearance range of 6%~10% of material thickness in this application, with 8% of material thickness being the optimal balance point.

[0098] Example 5

[0099] This embodiment uses a combination of parameters from the upper limit of the parameter range of the technical solution in this application to verify that the product can still meet the accuracy requirements under the upper limit of the parameters.

[0100] In this embodiment, the material selected is a chromium-zirconium-copper alloy (QCr1.0), in a solution-treated and aged state, with a thickness of 2.0 mm, a hardness of HV 135~150, a conductivity ≥78% IACS, and a tensile strength ≥420 MPa. The stamping equipment adopts a precision servo hydraulic press with a nominal pressure of 200 kN, a pressure control accuracy within ±1%, and a position control accuracy within ±0.01 mm.

[0101] The process parameters are set as follows: stamping speed is 30 mm / s (close to the upper limit), stamping pressure is approximately 60 kN, and holding time is 1.5 s (close to the upper limit). The die clearance is set to 10% of the material thickness, i.e., 0.20 mm; the punch fillet radius is 1.2 times the material thickness, i.e., 2.4 mm; and the die fillet radius is 2.0 times the material thickness, i.e., 4.0 mm. Springback compensation is achieved through die pre-deformation, with a compensation amount of 3%~4% of the target bending angle.

[0102] Lubrication uses a special stamping oil for copper alloys, with a viscosity of 45 mm² / s (close to the upper limit) and an oil application rate of 7 g / m². After molding, stress relief treatment is performed, with a heating temperature of 195℃ and a holding time of 1.8 hours.

[0103] The measurement results are shown in the table below (sample size n=50 pieces): First bending angle θ1 45.0° 44.65°~45.35° 45.06° 0.10° ±0.3° 98% qualified First bending radius R1 3.0mm 2.90~3.10mm 3.02mm 0.05mm ±0.15mm 100% qualified The angle of the second bend is θ2 90.0° 89.60°~90.40° 90.08° 0.12° ±0.3° 96% qualified The radius of the second bend is R2 3.0mm 2.89~3.11mm 3.03mm 0.05mm ±0.15mm 100% qualified This embodiment verifies that the product accuracy is reduced under the condition of parameters being close to the upper limit, but the basic requirements are still met. This shows that the technical solution of this application has a wide process window, which is beneficial to parameter adjustment and process control in actual production.

[0104] Example 6 This embodiment uses a combination of lower limit values ​​of the parameter range of the technical solution in this application to verify that the product can still meet the accuracy requirements under the lower limit conditions of the parameters.

[0105] In this embodiment, the material selected is a chromium-zirconium-copper alloy (QCr0.5) in a solution-treated and aged state, with a thickness of 2.0 mm, a hardness of HV 125~140, a conductivity ≥75% IACS, and a tensile strength ≥400 MPa. The stamping equipment adopts a precision servo hydraulic press with a nominal pressure of 100 kN, a pressure control accuracy within ±1%, and a position control accuracy within ±0.01 mm.

[0106] The process parameters are set as follows: stamping speed is 20 mm / s (close to the lower limit), stamping pressure is approximately 55 kN, and holding time is 0.5 s (close to the lower limit). The die clearance is set to 6% of the material thickness, i.e., 0.12 mm; the punch fillet radius is 0.8 times the material thickness, i.e., 1.6 mm; and the die fillet radius is 1.5 times the material thickness, i.e., 3.0 mm. Springback compensation is achieved through die pre-deformation, with a compensation amount of 1% to 2% of the target bending angle.

[0107] Lubrication uses a special stamping oil for copper alloys, with a viscosity of 15 mm² / s (close to the lower limit) and an oil application rate of 4 g / m². After molding, stress relief treatment is performed at a heating temperature of 155℃ and a holding time of 1.1 hours.

[0108] The measurement results are shown in the table below (sample size n=50 pieces): First bending angle θ1 45.0° 44.68°~45.32° 45.05° 0.09° ±0.3° 99% qualified First bending radius R1 3.0mm 2.91~3.09mm 3.01mm 0.04mm ±0.15mm 100% qualified The angle of the second bend is θ2 90.0° 89.65°~90.35° 90.06° 0.10° ±0.3° 98% qualified The radius of the second bend is R2 3.0mm 2.90~3.10mm 3.02mm 0.05mm ±0.15mm 100% qualified This embodiment verifies that the product accuracy basically meets the requirements under the condition of parameters being close to the lower limit, indicating that the technical solution of this application can guarantee product quality within the range of parameter fluctuations and has good process stability and tolerance.

[0109] Comparative Example 1 This comparative example uses a traditional bending process to manufacture the curved part of the measuring switch front baffle, and is used for comparison with the precision stamping process of this application.

[0110] Traditional bending processes use ordinary copper (T2) material with a thickness of 2.0mm, a hardness of HV 80~95, conductivity ≥98% IACS, and tensile strength ≥260 MPa. The bending equipment is a standard hydraulic bending machine with pressure control accuracy of ±3% and position control accuracy of ±0.1mm. The die material is 45# steel with a hardness of HRC 50~55 and a machining accuracy of ±0.05mm. Process parameters are as follows: bending speed 50~80mm / s, holding time 0.2~0.5s, no special lubrication or ordinary machine oil lubrication, no springback compensation or only rough compensation based on operational experience.

[0111] The measurement results are shown in the table below (sample size n=50 pieces): First bending angle θ1 45.0° 44.30°~45.80° 45.12° 0.25° ±0.5°~±1° 85% qualified First bending radius R1 3.0mm 2.78~3.22mm 3.05mm 0.12mm ±0.2~±0.5mm 88% qualified The angle of the second bend is θ2 90.0° 89.10°~91.10° 90.28° 0.35° ±0.5°~±1° 80% qualified The radius of the second bend is R2 3.0mm 2.75~3.28mm 3.08mm 0.15mm ±0.2~±0.5mm 82% qualified The performance indicators of traditional bending processes are as follows: bending angle tolerance is ±0.5°~±1°, bending radius tolerance is ±0.2~±0.5mm, surface roughness Ra is 1.8~3.2μm, batch consistency Cpk is 0.8~1.0, residual stress level is relatively high, and arc distance tolerance is ±0.2~±0.5mm.

[0112] The comparison results show that the dimensional accuracy, batch consistency and surface quality of the traditional bending process are significantly lower than those of the precision stamping process of this application, and cannot meet the stringent requirements of the high-precision measuring switch for the bending part of the front baffle.

[0113] Comparative Example 2 This comparative example uses a conventional stamping process (without optimized parameters) to manufacture the curved part of the measuring switch front baffle, in order to verify the necessity of optimizing the process parameters in this application.

[0114] The conventional stamping process uses the same chromium-zirconium-copper alloy material as in this application, but employs conventional stamping equipment, and the process parameters are not optimized. Specific parameters are as follows: the stamping equipment is a conventional hydraulic press, with pressure control accuracy of ±2% and position control accuracy of ±0.05mm; the stamping speed is 8mm / s (lower than the lower limit of this application), and the holding time is 0.3s (lower than the lower limit of this application); the die clearance is 12% of the material thickness (exceeding the upper limit of this application); the punch fillet radius is 0.6 times the material thickness (lower than the lower limit of this application); and the die fillet radius is 1.2 times the material thickness (lower than the lower limit of this application); there are no springback compensation measures; and no stress relief treatment.

[0115] The measurement results are shown in the table below (sample size n=50 pieces): First bending angle θ1 45.0° 44.45°~45.55° 45.08° 0.18° ±0.3° 92% qualified First bending radius R1 3.0mm 2.85~3.15mm 3.03mm 0.08mm ±0.15mm 95% qualified The angle of the second bend is θ2 90.0° 89.40°~90.60° 90.15° 0.22° ±0.3° 88% qualified The radius of the second bend is R2 3.0mm 2.84~3.16mm 3.04mm 0.09mm ±0.15mm 94% qualified The batch consistency Cpk of ordinary stamping process is about 0.8~1.0, the surface roughness Ra is about 1.2~2.0μm, and the residual stress level is relatively high.

[0116] The comparative results show that even using the same high-performance materials, if the process parameters are not optimized (insufficient equipment precision, stamping speed and holding time deviating from the preferred range, unreasonable die clearance and fillet radius, lack of springback compensation and stress relief treatment), the forming precision of the precision stamping process in this application cannot be achieved. This verifies the scientific nature and necessity of the process parameter system design in this application.

[0117] Comprehensive comparison The table below summarizes the main performance indicators of the embodiments of this application and the comparative examples: Example 1 (Optimal Parameters) ±0.24°~±0.27° 1.28~1.32 0.6~1.0μm Low optimal Example 2 (velocity gradient, 25 mm / s) ±0.24°~±0.27° 1.28~1.32 0.6~1.0μm Low optimal Example 3 (pressure holding gradient, 1.0s) ±0.24°~±0.27° 1.28~1.32 0.6~1.0μm Low optimal Example 4 (gap gradient, 8%) ±0.24°~±0.27° 1.28~1.32 0.6~1.0μm Low optimal Example 5 (Parameter Upper Limit) ±0.30°~±0.33° 1.05~1.08 0.8~1.2μm medium to low good Example 6 (lower limit of parameters) ±0.27°~±0.30° 1.08~1.12 0.7~1.1μm medium to low good Comparative Example 1 (Traditional Bending) ±0.75°~±1.05° 0.8~1.0 1.8~3.2μm high Poor Comparative Example 2 (Ordinary Stamping) ±0.54°~±0.66° 0.8~1.0 1.2~2.0μm Medium and high generally Note: The above data are sample data. Actual parameters need to be optimized and adjusted based on specific materials, equipment status, and process verification results.

[0118] The above comparison results show that the precision stamping forming method of this application, by accurately controlling key process parameters such as stamping speed, stamping pressure, holding time, die clearance and springback compensation, and in conjunction with high-precision stamping equipment and die system, can improve the angle accuracy of the front baffle bending part from ±0.5°~±1° of the traditional process to ±0.2°~±0.3°, the Cpk value from 0.8~1.0 to 1.25~1.35, the surface roughness from Ra 1.6~3.2μm to Ra 0.6~1.2μm, and the residual stress is significantly reduced, thereby achieving high-precision, high-consistency and high-reliability manufacturing of the front baffle bending part of the measurement switch.

[0119] Example 7 In some embodiments described above, a precision stamping method is proposed to obtain a high-precision front baffle bend by precisely controlling stamping parameters and combining them with springback compensation. However, in practical applications, relying solely on the control of the forming method is insufficient to ensure that the final product meets the stringent standards required for switching components in terms of geometry, structural integrity, and surface quality, especially for precision components with complex, multi-bend structures and high functional requirements. A lack of clear definition of the key characteristics of the final product may lead to unstable product performance, failing to meet assembly and usage requirements.

[0120] In this regard, such as Figure 2 As shown, this application proposes a curved portion of a measuring switch front baffle, which is manufactured using the aforementioned precision stamping method. It includes a first curved portion 101 and a second curved portion 102. The first curved portion 101 has a bending angle of 30°~60° and a bending radius of 2~4mm. The second curved portion 102 has a bending angle of 60°~120° and a bending radius of 2~4mm. The surface roughness Ra of the curved portion of the front baffle is ≤1.6μm.

[0121] Specifically, the curved portion of the front baffle 10 includes a first curved portion 101 and a second curved portion 102, indicating that the component has a multi-bending structure rather than a simple single bend. This multi-bending design is typically used to meet the complex assembly requirements of the switch structure, achieve specific mechanical property distribution, or optimize space utilization. For example, the first curved portion 101 may be used to mate with a fixed structure of the switch, while the second curved portion 102 may be used to connect with a movable part or form a specific guide groove. By setting different bending angles and radii, the overall shape and functional area of ​​the front baffle 10 can be precisely controlled, ensuring its accurate installation and reliable operation inside the switch.

[0122] The bending angle of the first bend 101 is limited to the range of 30° to 60°, and the bending radius is limited to the range of 2 mm to 4 mm. These parameters are crucial for ensuring the specific function and structural integrity of the front baffle 10 in the switch. The selection of this range aims to balance the functional requirements of the component with the forming properties of the material; for example, appropriate bending angles and radii help reduce stress concentration, prevent material cracking or excessive thinning, while ensuring sufficient structural strength and fatigue life.

[0123] The bending angle of the second bend 102 is limited to the range of 60° to 120°, and the bending radius is limited to the range of 2mm to 4mm. Compared with the first bend 101, the second bend 102 has a larger angle range, which usually means that it performs a different function or needs to adapt to a more complex spatial layout. For example, this bend may be used to form a steeper corner to achieve a tight fit with other components inside the switch, or as part of a flexible support structure. Similar to the first bend 101, the selection of the bending radius is also critical; it needs to meet the mechanical performance requirements of the component while ensuring the forming quality.

[0124] The surface roughness Ra of the curved portion of the front baffle is controlled below 1.6 μm. Surface roughness is an important indicator of the flatness of a material surface, and for precision switching components, low surface roughness offers multiple benefits. First, it reduces friction and wear, improving the smoothness of component movement and service life. Second, for components that may involve electrical contact, a smooth surface helps ensure stable electrical contact performance and reduces contact resistance. Furthermore, low roughness enhances the component's corrosion resistance and improves its appearance quality, making it more suitable for precision products. Achieving such low surface roughness typically requires precision stamping dies with extremely high surface finish, coupled with appropriate lubrication and forming processes.

[0125] By combining the precision stamping method with the specific structural and surface quality requirements of the front baffle bending portion using the above technical solution, it is possible to ensure that the manufactured front baffle bending portion has accurate geometric dimensions and excellent surface performance. Specifically, by clearly defining the bending angle and bending radius of the first bending portion 101 and the second bending portion 102, the front baffle 10 can accurately adapt to the complex internal structure and functional requirements of the switch, avoiding assembly difficulties or functional failures caused by dimensional deviations. Simultaneously, controlling the surface roughness of the front baffle bending portion to Ra≤1.6μm significantly improves the wear resistance, corrosion resistance, and electrical contact stability of the component, thereby effectively extending the service life of the switch and ensuring its reliability during long-term operation. This clear definition of the final product form and quality allows the high-precision advantages brought by the aforementioned precision stamping method to be fully realized, ensuring the consistency and stability of product performance and solving the problem that relying solely on method control is insufficient to guarantee the final product quality.

[0126] In some embodiments described above in this application, a curved portion of the front baffle of a measuring switch is proposed, comprising a first curved portion 101 and a second curved portion 102, and the bending angle, bending radius, and surface roughness are defined. However, in practical applications, in order to ensure the long-term stable operation of the measuring switch under harsh environments and to meet its higher requirements for signal transmission efficiency and structural strength, relying solely on these general parameters may not be sufficient to guarantee the comprehensive performance and reliability of the curved portion of the front baffle.

[0127] To address this, this application further proposes more precise limitations on the geometric parameters and material properties of the front baffle bending portion. Specifically, the bending angle of the first bending portion 101 is limited to 40°~50°, and the bending radius is 2.5~3.5mm; the bending angle of the second bending portion 102 is limited to 80°~100°, and the bending radius is 2.5~3.5mm. These parameters define the specific geometry of the front baffle bending portion. By limiting the bending angle and bending radius of the first bending portion 101 and the second bending portion 102 to a narrower range, precise geometric matching of the front baffle bending portion in the measuring switch can be ensured, thereby optimizing its mechanical response and electrical contact performance during switch operation. For example, a precise bending angle helps control the contact pressure and stroke of the contacts, while a precise bending radius effectively reduces stress concentration and improves the fatigue life of the component. These precise geometric parameters are obtained through optimized design based on the specific functional requirements and space constraints of the measuring switch.

[0128] Furthermore, the conductivity of the material in the bent portion of the front baffle is limited to no less than 75% IACS, and the tensile strength is limited to no less than 400 MPa. Material conductivity is a key indicator of a material's ability to transmit current. Limiting the conductivity of the bent portion of the front baffle to no less than 75% IACS ensures that, as a critical conductive component of the measurement switch, it can efficiently transmit electrical signals, minimizing resistance loss and heat generation. High conductivity materials help improve the switch's response speed and signal transmission stability, especially in high-frequency or high-current applications, effectively avoiding signal attenuation or overheating problems caused by insufficient conductivity. Tensile strength is an important mechanical property indicator of a material's resistance to tensile fracture. Limiting the tensile strength of the bent portion of the front baffle to no less than 400 MPa ensures that it can withstand the expected mechanical stress without plastic deformation or fracture during repeated operation and long-term use of the measurement switch. High tensile strength helps improve the structural stability and durability of the front baffle's bending section, extending its service life. This is especially important in applications requiring frequent operation or subject to significant impacts, effectively ensuring the reliability of the switch.

[0129] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for precision stamping forming of the bent portion of a measuring switch front baffle, characterized in that, The following steps are performed sequentially: S1. Provide metal material blanks; S2. The blank is formed by precision stamping process to form a front baffle with a first curved part and a second curved part; S3. During the forming process, control the stamping speed, stamping pressure, holding time, and die clearance, and adjust the actual bending angle to the target bending angle through springback compensation. The compensation amount of the springback compensation is 2% to 5% of the target bending angle. S4. Perform precision inspection on the formed front baffle to ensure that the bending angle tolerance of the first and second curved parts is controlled within the range of ±0.2°~±0.3°.

2. The precision stamping forming method according to claim 1, characterized in that, The precision stamping process is performed using precision stamping equipment, which has a pressure control accuracy of within ±1% and a position control accuracy of within ±0.01mm.

3. The precision stamping forming method according to claim 1, characterized in that, The stamping speed is 10~50mm / s, the stamping pressure is 50~200kN, and the holding time is 0.5~2s.

4. The precision stamping forming method according to claim 3, characterized in that, The stamping speed is 20~30mm / s, and the holding time is 0.5~1.5s.

5. The precision stamping forming method according to claim 4, characterized in that, The stamping speed is 25 mm / s, and the holding time is 1 s.

6. The precision stamping forming method according to claim 1, characterized in that, The die clearance is 6% to 10% of the material thickness, the punch fillet radius is 0.8 to 1.2 times the material thickness, and the die fillet radius is 1.5 to 2.0 times the material thickness; preferably, the die clearance is 8% of the material thickness, the punch fillet radius is preferably 1.0 times the material thickness, and the die fillet radius is preferably 1.8 times the material thickness.

7. The precision stamping forming method according to claim 1, characterized in that, The springback compensation is achieved through mold pre-deformation, with the mold pre-deformation amount being 1% to 3% of the target bending angle; or the springback compensation is achieved through multi-station progressive forming, with the deformation amount at each station increasing until the target bending angle is reached at the final station.

8. The precision stamping forming method according to claim 1, characterized in that, The precision stamping process uses copper alloy special stamping oil for lubrication. The viscosity of the lubricating oil is 10~50mm² / s, and the amount of oil applied is 3~8g / m². After forming, the process also includes a stress relief treatment step. The stress relief treatment temperature is 150~200℃, the holding time is 1~2 hours, and the cooling method is furnace cooling.

9. A curved portion of the front baffle of a measuring switch, characterized in that, The front baffle curved portion is manufactured by the precision stamping forming method according to any one of claims 1-8, and includes a first curved portion and a second curved portion. The first curved portion has a bending angle of 30°~60° and a bending radius of 2~4mm. The second curved portion has a bending angle of 60°~120° and a bending radius of 2~4mm. The surface roughness Ra of the front baffle curved portion is ≤1.6μm.

10. The front bumper bending portion according to claim 9, characterized in that, The bending angle of the first bending portion is 40°~50° and the bending radius is 2.5~3.5mm; the bending angle of the second bending portion is 80°~100° and the bending radius is 2.5~3.5mm; the material of the front baffle bending portion has an electrical conductivity ≥75% IACS and a tensile strength ≥400MPa.

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