Electronic throttle body machining process

Abstract

The invention relates to the technical field of electronic throttle body production and processing, and discloses an electronic throttle body processing technology which comprises the following steps that a liquid supporting medium is injected into an inner cavity of an electronic throttle body; subzero treatment is conducted on the electronic throttle valve body injected with the supporting medium, an inner supporting body for supporting the inner wall of the electronic throttle valve body is formed, and unstressed locking of the electronic throttle valve body and a positioning base is achieved; when the low-temperature state is maintained, the electronic throttle body is precisely machined; and after precision machining is completed, the electronic throttle body is heated, so that the inner supporting body is melted and removed from the inner cavity. The solid inner supporting body is formed in the inner cavity of the electronic throttle body workpiece, and stress-free locking of the workpiece and the base is achieved in the cryogenic environment. Initial stress and elastic deformation of the workpiece caused by clamping force are fundamentally avoided. And the final shape and position precision of the electronic throttle body are obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic throttle body production and processing, in particular to an electronic throttle body processing technology. Background Art

[0002] As a key component in the air intake system of modern automotive engines, the electronic throttle body's internal flow path, particularly the geometric accuracy and surface quality of the main orifice, has a decisive impact on engine performance, such as fuel efficiency, emissions control, and power response. Traditional machining methods, such as direct boring or milling of die-cast blanks, face multiple technical challenges.

[0003] First, electronic throttle bodies are typically die-cast from aluminum alloys. Castings made from this material often suffer from thin walls, complex structures, and insufficient rigidity. During high-precision internal hole machining, the workpiece's inherent strength is insufficient to withstand the cutting forces, leading to chatter, deformation, and even rejection. This inherent structural weakness makes it difficult for traditional rigid fixtures to effectively secure the workpiece, making it difficult to guarantee machining accuracy. Especially when pursuing micron-level or even submicron tolerances, machining stability becomes a bottleneck.

[0004] Secondly, in order to overcome the above-mentioned problem of insufficient rigidity, the industry has tried to use low-melting-point alloys as support media and inject them into the workpiece to enhance its processing rigidity. However, the existing technology still has obvious defects in the preparation of support media and its removal method. For example, some support media may have a single composition and lack an effective damping effect on processing chatter, resulting in unsatisfactory processing surface quality. In addition, if the solidification process of the support medium is not properly controlled, stress or microscopic defects may be generated inside, which will affect the overall uniformity and stability of the support body, and thus affect the processing accuracy.

[0005] More importantly, after precision machining is complete, efficiently and non-destructively removing the internal support medium is a common challenge facing existing technologies. Traditional rapid heating removal methods are often accompanied by severe temperature gradients and thermal shock, which are fatal for machined thin-walled precision parts. Uneven heating can cause thermal deformation in the workpiece, offsetting the increased precision achieved by precision machining. This makes it difficult for the final product's dimensional and positional accuracy to meet stringent technical requirements, and can even lead to the workpiece being scrapped. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides an electronic throttle body processing technology, which aims to fundamentally solve the problems of difficulty in ensuring the accuracy of thin-walled die-casting parts during precision machining, poor surface quality, and degradation of the final product accuracy due to improper removal of the supporting medium.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A process for processing an electronic throttle body, comprising the following steps:

[0008] S1. injecting a liquid supporting medium into the internal cavity of the electronic throttle body;

[0009] S2. Cryogenically treating the electronic throttle body injected with the supporting medium to reach a predetermined low temperature, thereby solidifying the supporting medium to form an inner support body that supports the inner wall of the electronic throttle body and achieves stress-free locking between the electronic throttle body and a positioning base;

[0010] S3. Precision machining the electronic throttle body while maintaining the low temperature state and ensuring that the inner support body remains in a solid state;

[0011] S4. After the precision machining is completed, the electronic throttle body is heated to melt the inner support body and remove it from the internal cavity.

[0012] In the initial step S1, a liquid support medium is injected into the internal cavity of the electronic throttle body. This step aims to completely fill the irregular internal contours of the workpiece with a material possessing specific thermophysical properties in a fluid form. This mechanism leverages the fluidity of the medium to ensure it reaches all internal surfaces without gaps, laying the material foundation for the subsequent formation of a complete, defect-free internal support structure. This process itself serves as a preparatory stage for the temporary "solidification" of the workpiece.

[0013] The subsequent step S2 synergistically realizes two core innovative mechanisms through a cryogenic treatment. The first is the forming mechanism of the inner support body: when the electronic throttle body injected with the supporting medium is placed in a cryogenic environment, the medium undergoes a liquid-solid phase change and solidifies into an inner support body that fits perfectly with the inner wall of the throttle body. The formation of this inner support body fundamentally changes the mechanical properties of the workpiece, that is, it temporarily transforms from a hollow, thin-walled, easily deformable structure to a highly rigid quasi-solid body. The electronic throttle body does not "resist" deformation from the outside, but "eliminates" the possibility of deformation from the inside, so that the workpiece can withstand cutting forces without deformation in subsequent processing.

[0014] Secondly, the stress-free locking mechanism is achieved: under the action of deep cooling, not only does the internal medium solidify, but the electronic throttle body workpiece itself is also firmly "frozen" to the positioning base that supports it due to the low temperature effect. This locking method relies entirely on thermodynamic effects and does not apply any external, uneven mechanical clamping force. It completely avoids the initial stress and elastic deformation of the workpiece caused by the clamping force of traditional fixtures, ensuring that the workpiece is positioned and locked in its most natural, stress-free state, creating ideal initial conditions for achieving the highest level of machining precision.

[0015] Proceeding to step S3, while maintaining the low temperature and solid internal support conditions established in the previous step, the electronic throttle body undergoes precision machining. The principle of this step lies in performing cutting in a thoroughly optimized physical environment. Thanks to the internal support, cutting forces are effectively absorbed and dispersed, preventing vibration or deflection in the thin-walled portion of the workpiece. Furthermore, since the workpiece is in a stress-free, locked state, its positional accuracy and stability are guaranteed during machining.

[0016] After precision machining is complete, step S4 heats the electronic throttle body, melting the inner support from a solid state to a liquid state. Leveraging the reversible phase change of the support medium, the temporary "tooling" support is then removed non-destructively. This entire process forms a complete closed loop, restoring the workpiece to its desired hollow, functional form without damaging the machined surface. The support medium also has the potential to be recycled and reused.

[0017] Preferably, the support medium is a functional microphase reinforced support medium, which is composed of a low melting point alloy matrix and functional reinforcement phase particles dispersed therein.

[0018] The support medium is not just any ordinary material with phase change capabilities, but a carefully designed functional microphase-enhanced support medium. Essentially, it is a composite material, consisting of a low-melting-point alloy matrix and functional reinforcement phase particles uniformly dispersed within it.

[0019] The synergistic effect of the two components of the support medium makes the solidified internal support body no longer just a filler that provides passive, static support, but an engineered component with active, multi-optimized functions. Among them, the low-melting-point alloy matrix provides the reversible phase transition required by the process, that is, completing the liquid-solid-liquid transition within a specific temperature range;

[0020] The dispersed functional reinforcement particles give the matrix two core functions that are crucial for the precision machining process and that the matrix itself does not possess:

[0021] The first is the dynamic stability enhancement mechanism. During precision machining, the interaction between the tool and the workpiece generates high-frequency vibrations. Functional reinforcement phase particles, by forming a large number of interfaces with the alloy matrix at the microscopic scale, constitute effective vibration energy dissipation units. When the cutting vibration wave propagates in the inner support, these interfaces will convert harmful vibration energy into insignificant heat energy through microscopic friction and damping effects, thereby greatly improving the dynamic stability of the entire "workpiece-inner support" system;

[0022] The second is the thermal management optimization mechanism. During the rapid cryogenic solidification or heating and melting process, the functional reinforcement phase particles with specific thermal properties build an efficient "heat conduction network" in the entire inner support body. In the cryogenic treatment of step S2, the cold can be transferred to every corner of the medium more quickly and evenly, ensuring the synchronization and uniformity of the solidification process. Similarly, in the heating removal stage of step S4, the heat is also evenly distributed through this network, avoiding local thermal shock to the precision surface of the processed workpiece, ensuring the gentleness and controllability of the entire process.

[0023] Preferably, the low melting point alloy matrix is ​​a bismuth-indium-tin alloy, and the functional reinforcement phase particles are boron nitride or graphite particles, which are used to improve the internal damping and thermal conductivity of the inner support body.

[0024] The low-melting-point alloy matrix is ​​preferably a ternary alloy of bismuth-indium-tin (Bi-In-Sn), which, as a ternary eutectic or near-eutectic alloy, has an extremely low and very sharp melting point. A sharp melting point means that when the alloy solidifies or melts, the transition from liquid to solid (or vice versa) is completed instantaneously within an extremely narrow temperature range, thereby avoiding the "mushy" or semi-solid area that appears within a larger temperature range. This ensures that during the cryogenic treatment of step S2, the inner support body can be solidified and formed quickly, evenly and densely; at the same time, during the heating and removal stage of step S4, the inner support body can be melted cleanly and neatly to avoid residues adhering to the processed precision surface, thereby ensuring the repeatability and reliability of the process.

[0025] Correspondingly, the functional reinforcement particles are preferably hexagonal boron nitride (h-BN) or spherical graphite particles. These particles are incorporated into the low-melting-point alloy matrix, transforming the internal support from a single-function component into a high-performance, multifunctional temporary fixture. Their specific mechanism of action is reflected in two aspects: improving the internal damping of the internal support and enhancing its thermal conductivity.

[0026] Preferably, step S2 further includes online monitoring of the curing process of the supporting medium by using an acoustic emission sensor.

[0027] During the cryogenic solidification process, temperature differentials and material shrinkage inevitably generate internal stresses within the support medium and at the interface between the medium and the inner wall of the electronic throttle body. When localized internal stresses exceed the material's microscopic strength limit, they can cause invisible microcracks or microscopic delamination between the support and the workpiece's inner wall. These microscopic defects can severely weaken the actual support stiffness and stability of the internal support. The process by which these defects develop is completely contained within the workpiece, making them undetectable using traditional methods.

[0028] The core of acoustic emission technology lies in the fact that when stress-releasing events such as microscopic cracking, friction, or plastic deformation occur within a material, energy is instantly released in the form of high-frequency elastic waves. Acoustic emission sensors are precisely suited to capturing these extremely weak elastic wave signals. Therefore, by placing acoustic emission sensors on the workpiece or its positioning base, it is possible to "hear" in real time every microcrack initiation or micro-debonding of the support medium during the solidification process.

[0029] The innovation of this online monitoring method lies in its transformation from a passive process reliant on theoretical calculations and post-testing to an active, transparent process with real-time information feedback. Rather than blindly executing the cooling process, the operator can, for the first time, qualitatively and in real time perceive the "health" and integrity evolution of the internal support structure during the molding process.

[0030] Preferably, the online monitoring includes: performing closed-loop feedback control on the cooling rate of the cryogenic treatment according to the signal of the acoustic emission sensor, so as to suppress the generation of micro cracks or micro peeling of the inner support body during the solidification process.

[0031] Online monitoring does not stop at the perception of the solidification state, but uses the acquired acoustic emission signal as a key feedback variable for closed-loop feedback control of the cooling rate of the cryogenic treatment. A direct response chain of "micro-defect event → real-time process adjustment" is established. The instantaneous intensity of the acoustic emission signal is directly related to the severity of the stress release event inside the inner support body. A gentle, low-intensity acoustic emission background signal usually indicates a smooth solidification process; once the signal intensity shows a steep peak that exceeds the preset threshold, it indicates that destructive microcracks or micro-peeling are occurring.

[0032] Leveraging this signal characteristic, the cryogenic cooling rate is transformed from a fixed, pre-programmed value to a variable that can be dynamically adjusted based on the material's true internal state. When the control system detects that the acoustic emission signal exceeds a threshold, it immediately responds by automatically reducing the cooling rate. This reduced cooling rate alleviates thermal stresses, suppresses the expansion of microdefects, and reduces the intensity of the acoustic emission signal back below a safe threshold. At this point, the control system determines that the process has stabilized and gradually returns to the initially set cooling rate to continue the efficient solidification process.

[0033] Preferably, the step S3 further includes monitoring the cutting state during the machining process or the stability of the inner support body by using the acoustic emission sensor.

[0034] The application value of the aforementioned acoustic emission sensor has been further expanded and deepened, with its monitoring function seamlessly extending from the curing stage (step S2) to the precision machining stage (step S3). During this stage, the sensor is assigned a dual monitoring task: monitoring the cutting state during machining or the stability of the inner support.

[0035] The mechanism of the first task is to diagnose the cutting status in real time. The essence of precision machining is the interaction between the tool and the material. This process is accompanied by shearing, fracture and plastic deformation of the material. These microscopic events will release energy in the form of stress waves, that is, generate acoustic emission signals. When a sharp tool performs stable cutting, the acoustic emission signal generated has a relatively stable characteristic; when the tool is worn, chipped, or vibration occurs during processing, the material removal process becomes discontinuous and accompanied by severe friction and impact, which will cause the characteristic parameters such as the amplitude and energy of the acoustic emission signal to have significant and identifiable changes;

[0036] The mechanism of the second task is to ensure the stability of the inner support body in real time. In step S3, the inner support body is the core component to resist the cutting force. Its own structural integrity and close fit with the inner wall of the workpiece are the lifeline to ensure the final processing accuracy. Although the inner support body has undergone strict closed-loop control and solidification, under the action of extreme cutting forces, there is still a potential risk of micro-damage initiation inside it or micro-slip between it and the workpiece surface. The role of the acoustic emission sensor here is to continuously "listen" to the "sound" coming from inside the inner support body. Once the cutting force exceeds the safety margin and causes any form of micro-yielding or failure of the support body, the stress wave released will be captured by the sensor.

[0037] Preferably, the precision machining in S3 is performed by dry cutting or minimal lubrication.

[0038] The cryogenic environment created by step S2 physically replaces the core function of traditional cutting fluids - cooling. During processing in step S3, the entire "workpiece-inner support body-positioning base" system is at an extremely low preset temperature, forming a huge "heat sink" (HeatSink). When the tool is cutting, the heat generated in the local area where the tip of the tool interacts with the material will be quickly transferred to the huge low-temperature body due to the huge temperature difference and absorbed and dissipated. This efficient, in-situ solid-state heat transfer cooling mechanism keeps the temperature of the cutting zone at a low level at all times, thereby naturally avoiding thermal deformation of the workpiece due to heat accumulation.

[0039] This inherent, continuous cryogenic environment provides a more effective and uniform cooling effect than external liquid spraying, minimizing or even eliminating the need for external cooling media. Therefore, dry cutting without cutting fluid, or minimal lubrication (MQL) that only requires spraying a very small amount of lubricating oil mist, becomes a feasible and ideal choice. It does not simply eliminate the cutting fluid, but rather satisfies the prerequisites for dry or quasi-dry machining by constructing a new physical machining environment. It deeply integrates the process flow with the concept of green manufacturing, which not only solves the environmental bottleneck of traditional machining methods, but also significantly simplifies the process equipment and post-processing procedures because there is no need to handle large amounts of cutting fluid, thus building a cleaner and more efficient manufacturing model.

[0040] Preferably, the heating in S4 to remove the inner support comprises:

[0041] In the first stage, induction heating is used to quickly melt and recover most of the inner support;

[0042] In the second stage, the remaining inner support body close to the inner wall is melted and removed by gentle heating.

[0043] In step S4, the final removal of the inner support, a refined, staged heating strategy is employed: to efficiently and quickly remove a large amount of solid support medium while absolutely avoiding any form of thermal damage or thermal deformation to the already precision-machined workpiece surface.

[0044] In the first stage, induction heating is used to quickly melt and recover most of the inner support body: after precision machining is completed, the interior of the workpiece is filled with a large amount of completely solidified support medium. An alternating magnetic field is used to directly induce eddy currents in the low-melting-point alloy inner support body that serves as a conductor. The thermal effect (Joule heat) of the eddy currents causes the support body itself to be quickly and integrally heated from the inside to above the melting point. This heating method applies almost all energy directly to the target object that needs to be melted, rather than heating the entire workpiece from the outside through slow heat conduction. In this way, most of the solid support medium can be converted into liquid and recycled in a short time, greatly shortening the process cycle time.

[0045] In the second stage, gentle heating is used to melt and remove the remaining inner support material close to the inner wall. After the rapid melting in the first stage, a thin layer of support medium remains attached to the inner wall of the electronic throttle body due to surface tension and other effects. This layer of medium is in direct contact with the precision-machined surface, which requires extremely high accuracy. At this stage, a gentle heating method is used, such as controlled infrared radiation or warm air circulation. Using a low-power-density, highly uniform heat source, the temperature of the entire workpiece and the remaining medium is slowly and synchronously raised to just above the melting point of the support medium. This minimizes temperature gradients between different parts of the workpiece, eliminating any risk of thermal deformation or thermal stress on the delicate surface.

[0046] Preferably, the target temperature of the low temperature state preset during the cryogenic treatment in S2 is -140°C to -160°C.

[0047] The primary rationale behind selecting this specific temperature range is to ensure the ultimate rigidity and stability of the inner support. By setting the target temperature in the deep-freezing zone of -140°C to -160°C, well below the melting point of the medium, the innovation lies in achieving a form of "deep solidification." At this temperature, the support medium not only completely transforms into a solid phase, but its microstructure also becomes denser and more stable due to the deep cooling effect. The material's hardness and elastic modulus are significantly increased, resulting in a truly high-strength, rigid core.

[0048] Secondly, selecting the right temperature range is crucial for achieving an ideal, stress-free locking effect. The "frozen" locking force between the workpiece and the positioning base is derived from the thermal contraction caused by the temperature difference between the two. Cryogenic temperatures of -140°C to -160°C are sufficient to induce sufficient macroscopic contraction between common workpiece materials (such as aluminum alloys) and base materials (such as steel), resulting in an extremely strong, gap-free interfacial lock.

[0049] Furthermore, machining at temperatures between -140°C and -160°C utilizes the material's improved cutting properties in cryogenic environments. For materials like aluminum alloys, commonly used in electronic throttle bodies, toughness decreases moderately within this temperature range, while hardness and brittleness increase. This change facilitates the formation of short, easily broken chips during cutting, reducing built-up edge and improving the quality of the machined surface.

[0050] Preferably, before step S1, the method further includes a step of pre-machining the reference surface of the die-cast blank of the electronic throttle body.

[0051] This preliminary step is not just a routine preparation; it establishes a unified, stable, and reliable reference system for all subsequent precision operations.

[0052] The original form of the electronic throttle body is usually a die-cast blank, which naturally has dimensional tolerances, draft angles, and surface irregularities. If such a blank is directly placed on the positioning base in step S2, the actual positioning posture of each workpiece will have slight and unpredictable differences. This will result in the final product still failing to meet the requirements and having poor consistency in key geometric tolerances (such as the positional relationship between the main hole and the mounting surface) due to random errors in the initial position, even if the subsequent cryogenic locking and precision machining process itself is flawless.

[0053] By pre-machining the die-cast blank's datum surface at the very beginning of the process, such as milling or grinding out highly flat and precisely positioned mounting surfaces or locating holes, a highly precise "coordinate origin" and "coordinate axis" are artificially created on the chaotic and imprecise original workpiece. This created datum surface becomes the sole and absolute basis for positioning throughout the entire subsequent process.

[0054] When a workpiece with this precise reference surface is placed on a precisely aligned positioning base, its spatial position and orientation are fixed and uniform. Thus, the stress-free locking achieved in step S2 not only locks a workpiece, but also locks a workpiece whose position and orientation are precisely calibrated.

[0055] The present invention provides a process for processing an electronic throttle body. It has the following beneficial effects:

[0056] 1. The present invention forms a solid internal support within the workpiece cavity and achieves stress-free locking between the workpiece and the base in a cryogenic environment. This solution temporarily transforms the thin-walled, easily deformed electronic throttle body into a highly rigid processing object. Compared to the traditional clamping method in the prior art that relies on external mechanical fixtures, it fundamentally avoids the initial stress and elastic deformation of the workpiece caused by the clamping force. At the same time, the strong internal support effectively resists the cutting forces during precision machining, solving the technical problem of flexural deformation in thin-walled areas, thereby significantly improving the final shape and positional accuracy of the electronic throttle body.

[0057] 2. This invention innovatively incorporates online acoustic emission monitoring and closed-loop feedback control technology. This method enables real-time "hearing" of stress release events within the support medium during cryogenic solidification. This overcomes the existing practice of blindly setting cooling process parameters based solely on experience, failing to detect and prevent microscopic defects within the support. By using acoustic emission signals as feedback to proactively adjust the cooling rate to suppress microcracks, this invention ensures the high quality and reliability of each internal support, providing a critical process guarantee for high consistency in subsequent high-precision machining.

[0058] 3. This invention utilizes a functional microphase-enhanced support medium. By dispersing functional reinforcement phase particles within a low-melting-point alloy matrix, the solidified internal support body possesses both excellent internal damping and thermal conductivity. Compared to technical solutions using a single-component support material, this invention not only effectively suppresses cutting chatter during precision machining through its high damping properties, but also optimizes the temperature field uniformity during deep cooling and heating processes through a high thermal conductivity network. This directly improves the quality of the machined surface and ensures the rapid and non-destructive removal of the support body, significantly enhancing the overall quality and operational efficiency of the process.

[0059] 4. The cryogenic processing environment constructed by this invention replaces the cooling function of traditional cutting fluids with its powerful "heat sink" effect, enabling precision machining using dry cutting or minimal quantity lubrication (MQL). This design radically changes the existing processing model that relies on large amounts of cutting fluid for cooling and lubrication, resolving the associated problems of high costs, environmental pollution, and complex waste fluid post-processing. Ultimately, this invention achieves a greener and cleaner precision machining process for electronic throttle bodies, with significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a production process flow chart of the present invention.

[0061] Figure 2 This is a schematic diagram of the pre-machining of the reference surface and the injection of the supporting medium for the die-cast blank of the electronic throttle body of the present invention;

[0062] Figure 3 This is a schematic diagram of the deep cryogenic solidification and precision processing of the inner support body;

[0063] Figure 4 Schematic diagram of the two-stage heating removal of the inner support body. DETAILED DESCRIPTION

[0064] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0065] Please see the attached Figure 1 The present invention provides a plurality of embodiments and comparative examples of an electronic throttle body processing process, the specific contents of which are as follows:

[0066] Example 1:

[0067] S1. Reference surface pre-machining

[0068] An electronic throttle body die-cast blank made of ADC12 aluminum alloy was selected, and its mounting surface was precisely milled using a CNC milling machine at room temperature to form a flat and smooth positioning reference surface to ensure the positioning uniformity of subsequent processes.

[0069] S2. Injection of support medium

[0070] A functional microphase-enhanced support medium was prepared. Its composition consisted of a bismuth-indium-tin (Bi-In-Sn) ternary eutectic alloy matrix, to which 1.5% by mass of hexagonal boron nitride (h-BN) particles with an average particle size of 5 μm were added as a functional reinforcement phase. After being heated to 85°C to completely melt into a fluid liquid, the medium was injected into the internal cavity of a pre-machined throttle body until it completely filled the cavity.

[0071] S3, deep cold curing and stress-free locking

[0072] The throttle body, injected with a support medium, is placed on a specially designed positioning base and moved together into a cryogenic treatment chamber. The liquid nitrogen spray system is activated for cooling, with the target temperature set at -150°C. During this process, the curing process is monitored online by an acoustic emission sensor arranged on the positioning base. The initial cooling rate is set at 25°C / min. When the acoustic emission signal energy exceeds the preset threshold, the closed-loop control system automatically reduces the cooling rate to 10°C / min for stress relief. After the signal stabilizes, the original rate is restored until the overall temperature reaches -150°C and stabilizes, completing the curing of the inner support body and the stress-free locking of the workpiece.

[0073] S4, low temperature precision machining

[0074] Maintaining a constant temperature of -150°C, the clamped workpiece is fed into the machining center. Using dry machining, the main bore of the electronic throttle body undergoes precision boring. During machining, acoustic emission sensors are used to monitor the cutting state and determine tool wear.

[0075] S5, two-stage heating removal

[0076] After machining is complete, the workpiece is rapidly heated using a 50kHz medium-frequency induction heating device, rapidly melting the internal support material into a liquid form within 90 seconds and dumping it for recycling. Subsequently, the workpiece is immersed in a circulating hot air oven at 90°C for gentle heating, completely melting the remaining thin layer of support material close to the inner wall and flowing out, ultimately resulting in a clean, high-precision finished electronic throttle body.

[0077] Example 2:

[0078] S1. Reference surface pre-machining

[0079] The reference surface is milled on an aluminum alloy electronic throttle body die-cast blank to obtain the reference plane used for precise positioning in subsequent processes.

[0080] S2. Injection of support medium

[0081] A functional microphase-enhanced support medium was prepared. Its components consisted of a bismuth-indium-tin alloy matrix with 1.0% by mass of spherical graphite particles with an average particle size of 3 μm. The medium was heated to 80°C to melt it into a liquid state and then injected into the internal cavity of the throttle body.

[0082] S3, deep cold curing and stress-free locking

[0083] The workpiece and positioning base are placed in a cryogenic chamber and cooled by a controlled cold air circulation system, with the target temperature set at -140°C. Acoustic emission sensors monitor the curing process online and provide closed-loop control to suppress the formation of internal microcracks and ensure the quality of the internal support body.

[0084] S4, low temperature precision machining

[0085] The throttle body is precisely machined while maintaining a low temperature of -140° C. In this embodiment, the main hole is bored using a minimal quantity lubrication (MQL) method to further improve the lubrication state of the cutting area.

[0086] S5, two-stage heating removal

[0087] After machining is complete, induction heating is first used to quickly melt and recover most of the inner supports. The workpiece is then immersed in a warm water bath at 85°C, where gentle heat conduction completely melts and rinses away the remaining support media adhering to the inner wall.

[0088] Example 3:

[0089] S1. Reference surface pre-machining

[0090] As in Example 1, the die-cast blank is pre-processed to obtain a positioning reference surface.

[0091] S2. Injection of support medium

[0092] A functional microphase-enhanced support medium was prepared, consisting of a bismuth-indium-tin alloy matrix with 2.0% by mass of hexagonal boron nitride (h-BN) particles with an average particle size of 7 μm. The medium was heated to 90°C to melt and then injected into the throttle body.

[0093] S3, deep cold curing and stress-free locking

[0094] The workpiece and positioning base are moved into a cryogenic chamber and rapidly cooled by direct injection of liquid nitrogen, with the target temperature set at -160°C. A closed-loop feedback control system based on acoustic emission signals is also used to optimize the cooling curve in real time to ensure the structural integrity of the internal support body at extreme cooling rates.

[0095] S4, low temperature precision machining

[0096] The throttle body is precision bored using dry machining at an ultra-low temperature of -160°C. The extremely low temperature helps reduce the brittleness of the material, facilitating chip breaking, while the acoustic emission system continues to monitor machining stability.

[0097] S5, two-stage heating removal

[0098] After precision machining is complete, the main support material is quickly recovered through induction heating. Subsequently, a controlled far-infrared radiation heating device is used to uniformly and gently program the workpiece to melt and remove the remaining medium adhering to the wall without thermal shock, ensuring that the dimensional accuracy of the final product is not affected.

[0099] Comparative Example 1:

[0100] Compared with Example 1, the difference is that the supporting medium used in step 2 is a pure bismuth-indium-tin (Bi-In-Sn) ternary eutectic alloy, and no hexagonal boron nitride (h-BN) particles are added thereto. The rest are the same.

[0101] Comparative Example 2:

[0102] Compared with Example 1, the difference is that during the deep cold solidification process of step three, no acoustic emission sensor is used for online monitoring and closed-loop feedback control. Instead, the temperature is lowered at a constant cooling rate of 25°C / min throughout the process until the target temperature of -150°C is reached. The rest are the same.

[0103] Comparative Example 3:

[0104] Compared with Example 1, the difference is that in the heating and removal process of step five, a two-stage heating method is not adopted. Instead, the workpiece after precision machining is directly placed in a 50kHz medium-frequency induction heating device, and is quickly heated at one time until the internal supporting medium is completely melted and then poured out for removal. The rest are the same.

[0105] Comparative Example 4:

[0106] Compared with Example 1, the difference is that the first step of pre-processing the reference surface is omitted, and the electronic throttle body die-cast blank without any pre-processing is directly used for the subsequent support medium injection and other processes, and the rest are the same.

[0107] Comparative Example 5:

[0108] Compared with Example 1, the difference is that in the functional microphase enhanced support medium prepared in step 2, the mass fraction of hexagonal boron nitride (h-BN) particles added is 10%, far exceeding the preferred range, and the rest are the same.

[0109] Test Example 1: Comparative test of process benchmark and support body molding quality

[0110] Purpose of the experiment:

[0111] The effect of die-cast blank datum surface pre-machining on improving the position tolerance of the main hole of the electronic throttle body relative to the installation datum surface was evaluated.

[0112] The effect of closed-loop acoustic emission control on the molding quality (stability) of the inner support body during cryogenic solidification was evaluated, and indirectly reflected in the vibration characteristics during processing.

[0113] Experimental Materials:

[0114] Electronic throttle body die-casting blank: several pieces.

[0115] Functional microphase-enhanced supporting medium: the components are the same as those in Example 1.

[0116] Positioning base, cryogenic treatment box, CNC milling machine, precision boring machining center, three-coordinate measuring machine (CMM), acoustic emission sensor and data acquisition system, surface roughness tester.

[0117] Experimental steps:

[0118] 1. Workpiece grouping and preparation:

[0119] Group A (Example 1): Ten electronic throttle body die-cast blanks were prepared. Processing was performed strictly according to the preparation steps of Example 1, including: datum surface pre-machining, injection of a functional microphase-enhanced support medium, cryogenic solidification and stress-free locking under closed-loop acoustic emission control, low-temperature precision machining, and two-stage heating removal.

[0120] Group B (Comparative Example 4 - No Reference Surface Pre-machining): Ten electronic throttle body die-cast blanks were prepared. The reference surface pre-machining step was omitted, and the unpretreated die-cast blanks were directly injected into the support medium. Subsequent processing was performed according to the remaining steps of Example 1 (including acoustic emission closed-loop control and cryogenic processing).

[0121] Group C (Comparative Example 2 - No AE Closed-Loop Control): Ten electronic throttle body die-cast blanks were prepared. Reference surface pre-machining and support medium injection were performed according to the procedures in Example 1. However, during the cryogenic solidification stage, online monitoring and closed-loop feedback control with an AE sensor were not used. Instead, the temperature was cooled at a constant rate of 25°C / min until the target temperature reached -150°C. The remaining processing steps were the same as in Example 1.

[0122] 2. Finished product position measurement (for group A and group B):

[0123] After all workpieces in Group A and Group B have been fully machined and cooled to room temperature, each finished product is measured on a coordinate measuring machine;

[0124] Take the installation reference surface of each workpiece as the measurement reference and measure the axis position tolerance of its main hole;

[0125] Record the position measurements of each workpiece.

[0126] 3. Vibration signal collection during machining (for Group A and Group C):

[0127] When the workpieces in Groups A and C are being subjected to precision boring in step 4, a high-precision vibration sensor is installed near the spindle or workpiece fixture of the machining center;

[0128] Synchronously collect vibration signal data (such as vibration acceleration or amplitude) during the machining process (especially during the boring tool entry and cutting stages);

[0129] Record the average vibration amplitude or characteristic frequency vibration energy of each workpiece during the machining process.

[0130] 4. Result test and data recording:

[0131] For Groups A and B (Position Test): After all machining and support removal steps are complete, the finished electronic throttle bodies from Groups A and B are placed on a coordinate measuring machine (CMM). The position of the center axis of the main hole of each workpiece is measured using the pre-set mounting surface as a reference, and the position data for each workpiece is recorded.

[0132] For Groups A and C (machining stability test): During the precision boring process in step 4, the machining center's integrated acoustic emission sensor system was activated to record the acoustic emission signals generated during the boring process in real time (e.g., RMS value, event rate, etc.). The signal characteristics during the stable cutting phase and the cutting force abrupt change were particularly important. Acoustic emission data for each workpiece was collected during machining and spectral analysis was performed to assess the presence of machining chatter.

[0133] The experimental results are shown in Table 1:

[0134] Table 1: Comparative data of main hole position (relative to the installation reference surface, unit: mm)

[0135] Workpiece number Example 1 (Group A) Comparative Example 4 (Group B) 1 0.005 0.048 2 0.007 0.061 3 0.004 0.055 4 0.006 0.042 5 0.009 0.073 6 0.008 0.059 7 0.005 0.066 8 0.007 0.052 9 0.006 0.071 10 0.004 0.064

[0136] Table 2: Comparison of the average amplitude of acoustic emission signals (relative units) during precision boring

[0137] Workpiece number Example 1 (Group A) Comparative Example 2 (Group C) 1 1.2 2.8 2 1.5 3.5 3 1.1 2.9 4 1.4 3.1 5 1.3 3.7 6 1.0 3.2 7 1.6 3.8 8 1.2 3.0 9 1.4 3.4 10 1.1 3.6

[0138] First, by comparing the performance of Example 1 (Group A) and Comparative Example 4 (Group B) in terms of the main hole positioning, it can be clearly seen that the workpiece that has been pre-processed on the reference surface has significantly better and more consistent final main hole positioning relative to the installation reference surface. This result confirms the innovative mechanism of pre-processing the reference surface of the die-cast blank before injecting the supporting medium - that is, by artificially creating a high-precision, unified "coordinate origin" at the initial stage of the processing chain. This pre-established precise reference system fundamentally eliminates the uncertainty caused by the original size and form and position errors of the die-cast blank. When all subsequent precision operations, including cryogenic locking and processing, are based on this unified benchmark, the high accuracy and repeatability of the final product in key form and position tolerances can be ensured, avoiding the accumulation of total errors caused by initial positioning deviations.

[0139] Secondly, by comparing the differences in acoustic emission signals during precision boring between Example 1 (Group A) and Comparative Example 2 (Group C), the importance of the online monitoring and closed-loop feedback control technology of acoustic emission adopted by the present invention is highlighted. During the cryogenic solidification process, the Example 1 group effectively suppressed the microcracks or stress concentration that may occur inside the support medium by real-time monitoring and regulating the cooling rate. This fine control of the "deep solidification" process of the support body ensures that the inner support body has excellent structural integrity and mechanical stability. Therefore, in the subsequent low-temperature precision processing link, it can provide more uniform and rigid support, effectively absorb and damp the vibrations generated during the cutting process, thereby making the processing smoother and the acoustic emission signal amplitude lower.

[0140] In contrast, the lack of this closed-loop control in Comparative Example 2 may have hidden defects in its internal support, resulting in an inability to effectively suppress chatter during machining and a higher acoustic emission signal amplitude. This further validates the innovative mechanism of ensuring machining stability by optimizing the internal quality of the support.

[0141] Test Example 2: Comparative test of the effect of the internal support components on the processing process

[0142] Purpose of the experiment:

[0143] Evaluate the effect of pure support media (no reinforcement phase) on precision machined surface quality.

[0144] The negative impact on surface quality when the amount of functional reinforcement phase particles added exceeds the preferred range was evaluated.

[0145] Verify the positive effect of the optimal ratio of functional enhanced support medium on suppressing cutting chatter and improving surface roughness.

[0146] Experimental Materials:

[0147] Electronic throttle body die-casting blank: several pieces.

[0148] Support medium: including pure bismuth-indium-tin eutectic alloy, support medium containing 1.5% h-BN particles (component of Example 1), and support medium containing 10% h-BN particles.

[0149] Positioning base, cryogenic treatment box, CNC milling machine, precision boring machining center, surface roughness tester.

[0150] Experimental steps:

[0151] 1. Sample preparation and grouping:

[0152] Group A (Example 1): 10 die-cast blanks were selected and processed strictly according to the complete process flow of Example 1. The core of the process is to use a functional microphase-enhanced support medium containing 1.5% h-BN particles.

[0153] Group B (Comparative Example 1): Ten die-cast blanks were selected and the process flow was similar to that of Example 1, except that the supporting medium was a pure bismuth-indium-tin (Bi-In-Sn) ternary eutectic alloy, without any functional reinforcement particles. All other steps were carried out similarly to Example 1.

[0154] Group C (Comparative Example 5): 10 die-cast blanks were selected and the process flow was similar to that of Example 1, except that the mass fraction of hexagonal boron nitride (h-BN) particles added to the support medium was 10%. The remaining steps were carried out similarly to Example 1.

[0155] 2. Result test and data recording:

[0156] Post-processing surface roughness measurement: After all workpieces in Groups A, B, and C have completed all machining and support removal steps and cooled to room temperature, use a high-precision surface roughness tester to measure the inner wall of each finished electronic throttle body's main hole at multiple points. Record the average surface roughness Ra value of each workpiece's main hole.

[0157] Table 1: Comparative data of the surface roughness of the inner wall of the main hole of the electronic throttle body (Ra, unit: μm)

[0158]

[0159]

[0160] When comparing the surface roughness data of Example 1 (Group A) and Comparative Example 1 (Group B), it can be found that the surface roughness of the inner wall of the main hole of the workpiece processed using a support medium containing functional reinforcing phase particles is significantly better than that of the workpiece using a pure support medium. This directly verifies the innovative mechanism of the functional microphase enhanced support medium - by dispersing functional reinforcing phase particles in the low-melting point alloy matrix, the internal damping performance of the internal support body after solidification can be effectively improved. This enhanced damping effect can more effectively absorb and suppress cutting chatter during precision boring, thereby avoiding unstable relative motion between the tool and the workpiece, and ultimately ensuring the smoothness and high quality of the machined surface.

[0161] Secondly, by analyzing the experimental data of Comparative Example 5 (Group C), we can see that when the amount of functional reinforcing phase particles added exceeds the optimization range, it leads to the degradation of surface roughness, even if its performance is still better than that of pure support medium. This phenomenon reveals another deep mechanism of functional microphase enhancement: the amount of particles added is not the more the better, but there is an optimization range. Excessive hard particles may affect the homogeneity and density of the support medium after solidification, and even form new microscopic stress concentration points or cause uneven local support stiffness during processing, thereby affecting the stability of cutting. The present invention achieves the optimal balance of the mechanical properties of the support medium by precisely controlling the type, particle size and addition amount of the reinforcing phase, ensuring that it does not introduce new processing defects while providing high damping performance.

[0162] In summary, this test case strongly demonstrates the innovative nature of the present invention's internal support medium composition. By introducing and optimizing functional microphase-reinforced particles, the present invention achieves synergistic optimization of the support medium and the cutting process. This synergistic effect not only enhances the internal support's ability to withstand cutting forces, but more importantly, its excellent internal damping performance directly translates into effective suppression of cutting chatter during machining, significantly improving the surface quality of the critical inner bore of the electronic throttle body.

[0163] Test Example 3: Comparative Test of the Effect of Heating Removal Method on the Precision of Finished Products

[0164] Purpose of the experiment:

[0165] Evaluate the thermal deformation that may occur in the workpiece when removing the support medium through single-stage rapid heating.

[0166] The advantages of the two-stage gentle heating removal method of the present invention in ensuring the stability of the processed precision dimensions are verified.

[0167] Experimental Materials:

[0168] Several pieces of die-cast blanks for electronic throttle bodies.

[0169] The functional microphase-enhanced support medium described in Example 1.

[0170] Precision boring machining center.

[0171] High-precision internal diameter measuring instruments (e.g. pneumatic gauges or high-precision three-point internal micrometers).

[0172] Medium frequency induction heating device.

[0173] Circulating hot air box or controlled far infrared radiation heating device.

[0174] Experimental steps:

[0175] 1. Sample preparation and grouping:

[0176] Group A (Example 1): 10 die-cast blanks were selected and processed according to the entire process flow of Example 1, but the inner support body was not removed immediately after the precision machining was completed.

[0177] Group B (Comparative Example 3): 10 die-cast blanks were selected and processed in accordance with the entire process flow of Example 1. However, after the precision machining was completed, the inner support body was not immediately removed.

[0178] 2. Initial accuracy measurement (performed on both sets of workpieces):

[0179] Initial accuracy measurements were performed on all workpieces from Groups A and B after the precision machining steps were completed but before the support media was removed.

[0180] Using a high-precision internal diameter measuring instrument, the roundness of each workpiece's main hole is measured at multiple points at room temperature, and its initial roundness value is recorded. At this stage, all workpieces are in an internally supported state.

[0181] 3. Support medium removal and final state measurement:

[0182] Group A (Example 1 Removal Method): Group A workpieces were removed using a two-stage heating process. First, the workpieces were rapidly heated using a medium-frequency induction heating device, melting the majority of the internal support medium and dumping it for recovery. Subsequently, the workpieces were placed in a circulating hot air oven for gentle heating, completely melting the remaining thin layer of support medium and allowing it to flow out, ultimately yielding a clean finished product. After the workpieces cooled to room temperature, the roundness of their main holes was measured again using a high-precision internal diameter measuring instrument, and the final roundness value was recorded.

[0183] Group B (Comparative Example 3 Removal Method): Group B workpieces were removed using a single-stage rapid heating process. The entire workpiece was placed directly into a medium-frequency induction heating device, rapidly heated once until the internal support medium was completely melted, and then removed by pouring. After the workpiece cooled to room temperature, the roundness of its main hole was measured again using a high-precision internal diameter measuring instrument, and the final roundness value was recorded.

[0184] 4. Data Analysis:

[0185] The change in the roundness of the main hole of each workpiece in Group A and Group B before and after heating and removal was calculated respectively (Δ roundness = | final roundness - initial roundness | Δ roundness = | final roundness - initial roundness |).

[0186] The average values ​​and dispersion of the roundness changes of the two groups of workpieces were compared to evaluate the effects of different removal methods on the maintenance of machining accuracy.

[0187] Table 1: Comparative data of the roundness change of the main hole of the electronic throttle body (Δ roundness, unit: μm)

[0188]

[0189]

[0190] By comparing the main hole roundness change data of Example 1 (Group A) and Comparative Example 3 (Group B), it can be significantly found that the roundness change of the workpieces in Group A using the two-stage heating removal method is significantly smaller than that of the workpieces in Group B using the single-stage rapid heating removal method. This difference reveals the superiority of the unique two-stage heating removal mechanism of the present invention - that is, first removing most of the supporting medium by rapid heating, and then thoroughly removing the residual thin layer by gentle heating. This strategy effectively avoids the overall thermal shock and local overheating of the workpiece that may be caused by traditional single-stage rapid heating. Since the electronic throttle body is a thin-walled structure, it is extremely sensitive to temperature changes. Sudden heating and cooling can easily cause uneven thermal expansion and contraction, resulting in deformation of the processed precision surface. The present invention minimizes this thermal stress by controlling the temperature gradient in stages.

[0191] The test results of Comparative Example 3 demonstrate the limitations of rapid, brute-force heating removal. When a workpiece is subjected to drastic temperature fluctuations in a very short period of time, the difference in thermal conductivity between the workpiece and the internal support medium can lead to a transient temperature difference and significant thermal stress. This thermal stress is particularly prone to accumulating in thin-walled and complex areas, leading to irreversible degradation of the micron-level or even submicron-level positional accuracy achieved. Even the most precise machining process can be thwarted if the removal step is not performed properly.

[0192] In summary, this test case fully demonstrates the critical role of the present invention's two-stage heating removal technique in ensuring the precision of the final electronic throttle body. Through this refined temperature control strategy, the present invention effectively addresses the existing technical challenge of workpiece thermal deformation caused by improper support body removal. It not only optimizes removal efficiency but, more importantly, mechanically safeguards the integrity of the precision machining results, ensuring that the electronic throttle body maintains its high dimensional and positional accuracy requirements after the entire machining process.

[0193] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for processing an electronic throttle body, characterized in that: The following steps are involved: S1. injecting a liquid supporting medium into the internal cavity of the electronic throttle body; S2. Cryogenically treating the electronic throttle body injected with the supporting medium to reach a predetermined low temperature, thereby solidifying the supporting medium to form an inner support body that supports the inner wall of the electronic throttle body and achieves stress-free locking between the electronic throttle body and a positioning base; S3. Precision machining the electronic throttle body while maintaining the low temperature state and ensuring that the inner support body remains in a solid state; S4. After the precision machining is completed, the electronic throttle body is heated to melt the inner support body and remove it from the internal cavity.

2. The electronic throttle body processing technology according to claim 1, characterized in that: The support medium is a functional microphase reinforced support medium, which is composed of a low melting point alloy matrix and functional reinforced phase particles dispersed therein.

3. The electronic throttle body processing technology according to claim 2, characterized in that: The low-melting-point alloy matrix is ​​a bismuth-indium-tin alloy, and the functional reinforcement phase particles are boron nitride or graphite particles, which are used to improve the internal damping and thermal conductivity of the inner support body.

4. The electronic throttle body processing technology according to claim 1, characterized in that: The step S2 further includes online monitoring of the solidification process of the supporting medium by using an acoustic emission sensor.

5. The electronic throttle body processing technology according to claim 4, characterized in that: The online monitoring includes: performing closed-loop feedback control on the cooling rate of the cryogenic treatment according to the signal of the acoustic emission sensor, so as to suppress micro cracks or micro peeling of the inner support body during the solidification process.

6. The electronic throttle body processing technology according to claim 1, characterized in that: The step S3 further includes monitoring the cutting state during the machining process or the stability of the inner support body by using the acoustic emission sensor.

7. The electronic throttle body processing technology according to claim 1, characterized in that: The precision machining in S3 is performed by dry cutting or minimal lubrication.

8. The electronic throttle body processing technology according to claim 1, characterized in that: The heating in S4 to remove the inner support comprises: In the first stage, induction heating is used to quickly melt and recover most of the inner support; In the second stage, the remaining inner support body close to the inner wall is melted and removed by gentle heating.

9. The electronic throttle body processing technology according to claim 1, characterized in that: The target temperature of the low temperature state preset during the cryogenic treatment in S2 is -140°C to -160°C.

10. The electronic throttle body processing technology according to claim 1, characterized in that: Before step S1 , the method further includes a step of pre-machining the reference surface of the die-cast blank of the electronic throttle body.

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