Injection molding processing technology of gearbox proportional electromagnetic valve body

Abstract

The invention provides an injection molding processing technology of a gearbox proportional electromagnetic valve body, which belongs to the technical field of injection molding processing, and comprises the following steps: reference selection: constructing a central positioning system by taking a valve plate as a carrier, fixedly connecting a cylindrical central column, calibrating the coaxiality error of the axis of the central column and the reference axis of the valve plate, and taking the top end surface of the central column as a primary injection molding reference surface; during secondary injection molding, a magnetic conductive magnetic flux tube is embedded in a preset positioning hole of the valve body core, and the inner hole axis of the valve body core serves as the reference axis of secondary injection molding; high-precision sliding blocks are distributed in the circumferential direction of a mold cavity, and the outer contour size of a valve body core is controlled; in the secondary injection molding stage, a valve body core inner hole serves as a positioning reference, positioning connection of a valve body core and a secondary mold is achieved, the form and location tolerance of a valve body shell is controlled through mold temperature field uniformity, the bottleneck that traditional injection molding experience depends on is broken through, and the injection molding machining process accuracy is guaranteed; and a replicable digital solution is provided for batch manufacturing of the high-precision gearbox valve body.

Description

Technical Field

[0001] The present invention relates to the technical field of injection molding, in particular to an injection molding process for a gearbox proportional solenoid valve body. Background Art

[0002] In automotive automatic transmissions, the proportional solenoid valve body is a core flow control component. The precision of its injection molding process directly determines the solenoid valve's response characteristics and sealing performance, which in turn affects the transmission's shifting smoothness, power transmission efficiency, and reliability. However, existing injection molding processes for transmission proportional solenoid valve bodies have significant deficiencies in the accuracy of datum selection and the controllability of machining precision. This results in the valve body's geometric and positional tolerances failing to meet the design requirements of high-end transmissions.

[0003] In traditional processes, the first injection molding process mostly uses the mold parting surface or simple positioning pins as a reference, and no center positioning system is built for the valve plate. Although some solutions use a center column, they are only calibrated by manual visual inspection or simple measuring tools. The coaxiality error between the center column axis and the valve plate reference axis is often ≥0.05mm, and the parallelism error between the center column end face and the fixed template of the injection molding machine is ≥0.05mm, resulting in periodic deviations in the inner hole and outer contour of the valve body core due to the reference offset during molding. During subsequent assembly, the matching clearance between the valve core and the valve body fluctuates by more than ±0.05mm. The secondary injection molding needs to be based on the first molded valve body core, but the existing technology mostly relies on the outer contour of the valve body core (such as edges and step surfaces) for positioning, which has two major defects: The outer contour is prone to benchmark failure due to shrinkage and deformation during the initial injection molding (e.g. outer contour roundness error ≥ 0.04mm); Due to the lack of active positioning constraints on the valve body core (such as the absence of positioning elements such as magnetic flux tubes), the valve body core is prone to random offset in the secondary injection mold (offset ≥ 0.03mm), which directly leads to a coaxiality error of ≥ 0.1mm between the valve body shell and the valve body core, destroying the magnetic circuit symmetry of the solenoid valve.

[0004] Existing molds often use pneumatic or hydraulic cylinders to drive the slider, achieving a positioning accuracy of only ±0.05mm. These molds lack real-time displacement feedback and closed-loop control. When the valve core's outer contour needs to be controlled within ±0.03mm, slider positioning errors can directly lead to dimensional deviations (e.g., actual dimensional fluctuations of up to ±0.08mm). Furthermore, due to the lack of coordinated precision between the center column and the slider, the coaxiality error of the valve core's inner bore is often ≥0.06mm, increasing the risk of valve core sticking after assembly by over 30%.

[0005] The secondary injection molding process requires the valve body shell to be formed. Its form and position tolerances (such as coaxiality and parallelism) are sensitive to the mold temperature field. The existing process mostly uses zoned heating and natural cooling. The temperature difference between different areas of the mold cavity is ≥10℃, which leads to uneven cooling and shrinkage of the valve body shell: The difference in axial shrinkage rate is as high as 1.2%~1.8%, resulting in a verticality error of ≥0.08mm between the shell and the valve body core; the uneven radial shrinkage causes a roundness error of ≥0.05mm, which destroys the integrity of the sealing interface of the solenoid valve and increases leakage by 20%~30%.

[0006] The above defects directly lead to: unstable fitting clearance between the solenoid valve core and the valve body, gear shift response time fluctuation exceeding ±50ms, causing gear shift jerking in the transmission; valve body seal failure and increased hydraulic oil leakage rate; assembly stress concentration caused by excessive valve body shape and position tolerances shortens the fatigue life of the solenoid valve.

[0007] Therefore, the present invention proposes an injection molding process for a transmission proportional solenoid valve body. Summary of the Invention

[0008] The present invention provides an injection molding process for a transmission proportional solenoid valve body, which is used to solve the above-mentioned technical problems.

[0009] The present invention provides an injection molding process for a gearbox proportional solenoid valve body, comprising: Reference selection: During the first injection molding, a center positioning system is constructed using the valve plate as a carrier. A cylindrical center column is fixed to the geometric center of the valve plate. The coaxiality error between the center column axis and the valve plate reference axis is calibrated using a three-coordinate measuring machine to ≤0.01mm. The top end face of the center column is used as the reference surface for the first injection molding. The parallelism error between the reference surface and the fixed plate of the injection molding machine is within 0.02mm. During secondary injection molding, the valve body core molded by the first injection molding is used as the reference workpiece, and a magnetic flux tube is embedded in the preset positioning hole of the valve body core. The inner hole axis of the valve body core is used as the reference axis of the secondary injection molding. Processing control: During the first injection molding stage, four sets of high-precision sliders are evenly distributed around the mold cavity. The sliders are driven by servo motors. The outer contour of the valve body core is controlled by the radial movement of the sliders. At the same time, the positioning effect of the center column is used to ensure that the coaxiality of the inner hole is ≤0.03mm. During the secondary injection molding stage, the inner hole of the valve body core is used as the positioning reference, and clearance fit is used to achieve the positioning connection between the valve body core and the secondary mold. The form and position tolerance of the valve body shell is controlled by the uniformity of the mold temperature field. Preferably, the center column is made of mold steel with a hardness ≥HRC55, the surface of the column is precision ground, the cylindricity error is ≤0.005mm, and the surface roughness Ra is ≤0.1μm; the center column and the valve plate are connected by a combination of locating pins and bolts, and the locating pin diameter tolerance band is H7 / g6. Preferably, the slider system for the first injection molding includes a guide mechanism, a pressure sensor and a displacement feedback device. The guide mechanism adopts a ball guide rail, the pressure sensor monitors the slider injection pressure in real time, and the displacement feedback device forms a closed-loop control with the injection molding machine control system. Preferably, the first injection molding process parameters are set as follows: injection pressure 90-110 MPa, melt temperature 220-240° C., a circulating oil cooling system is used in the cooling stage, and the cooling time is set to 12-18 seconds according to the valve body core wall thickness. Preferably, the magnetic flux tube is a hollow cylinder made of a soft magnetic alloy material, the outer diameter has a matching tolerance of H8 / h7 with the valve body core positioning hole, and the length direction exceeds the end face of the positioning hole by 2-5 mm; The electromagnetic positioning device of the secondary injection mold includes 6 groups of evenly distributed electromagnetic coils, which are supplied with stable DC current through a thyristor rectifier. Preferably, the positioning pin during secondary injection molding adopts a combined structure of conical and cylindrical surfaces, the conical surface angle of 15°±1° is used for initial guidance, and the cylindrical surface length of 5-10mm is used for precise positioning; the positioning pin material is cemented carbide, and the surface is PVD-treated to form a diamond-like coating with a thickness of 5-8μm.

[0010] Preferably, the secondary injection molding process parameters are set as follows: injection pressure 110-140 MPa, melt temperature 240-270° C., segmented cooling method, and total cooling time 25-35 seconds.

[0011] Preferably, CAD / CAM integrated technology is used for process design, a three-dimensional parametric model including the valve body core and the shell is established, and tetrahedron units are used for finite element meshing; Set a multi-objective optimization function for each grid cell , including filling balance F1, pressure gradient F2, and temperature uniformity F3;

[0012]

[0013]

[0014] in, is the pressure difference between the flow channel inlet and the cavity end under the corresponding grid unit; is the total length of the flow channel under the corresponding grid unit; is the dynamic viscosity of the melt; is the melt flow rate under the corresponding grid unit; 、 、 is the weight coefficient; Indicates the maximum pressure difference per unit length; They represent the maximum balance, minimum balance, and average balance of the cavity corresponding to the grid unit; T Respectively represent the maximum temperature, minimum temperature and average temperature of the melt; The gate coordinates and diameter are used as decision variables, and the constraint condition is that the distance between the gate and the parting surface is ≥3mm. The genetic algorithm is used to preliminarily determine the gate position. By iterative calculation, the objective function of all grid cells The initially determined gate position is converged to the global minimum to determine the final gate position. Preferably, the mold is processed using a five-axis CNC machine tool, the cavity surface is precisely processed by electric spark machining and then ground and polished, with a roughness of Ra≤0.2μm, and the core part is processed by wire cutting.

[0015] Preferably, the online detection system includes a non-contact laser probe and a machine vision device to detect the aperture, outer contour dimensions and form and position tolerances of the valve body core and the valve body shell in real time; the detection data is transmitted to the PLC control system in real time via industrial Ethernet, triggering automatic adjustment of the injection molding parameters to form a dynamic compensation mechanism for processing accuracy.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention provides an injection molding process for a transmission proportional solenoid valve body, comprising: datum selection: constructing a center positioning system with a valve plate as a carrier, fixing a cylindrical center column, calibrating the coaxiality error between the center column axis and the valve plate reference axis, and using the top end face of the center column as a primary injection molding datum surface; during secondary injection molding, embedding a magnetic flux tube into a preset positioning hole of a valve body core, and using the inner hole axis of the valve body core as a datum axis for secondary injection molding; machining control: arranging high-precision sliders in the circumference of the mold cavity to control the outer contour size of the valve body core; in the secondary injection molding stage, using the inner hole of the valve body core as a positioning datum to realize the positioning connection between the valve body core and the secondary mold, controlling the form and position tolerances of the valve body shell by the uniformity of the mold temperature field, breaking through the bottleneck of reliance on traditional injection molding experience, ensuring the accuracy of the injection molding process, and providing a replicable digital solution for the mass production of high-precision transmission valve bodies.

[0017] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 The figure is a flow chart of an injection molding process for a transmission proportional solenoid valve body according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0021] The present invention provides an injection molding process for a gearbox proportional solenoid valve body, such as Figure 1 As shown, including: Reference selection: During the first injection molding, a center positioning system is constructed using the valve plate as a carrier. A cylindrical center column is fixed to the geometric center of the valve plate. The coaxiality error between the center column axis and the valve plate reference axis is calibrated using a three-coordinate measuring machine to ≤0.01mm. The top end face of the center column is used as the reference surface for the first injection molding. The parallelism error between the reference surface and the fixed plate of the injection molding machine is within 0.02mm. During secondary injection molding, the valve body core molded by the first injection molding is used as the reference workpiece, and a magnetic flux tube is embedded in the preset positioning hole of the valve body core. The inner hole axis of the valve body core is used as the reference axis of the secondary injection molding. Processing control: During the first injection molding stage, four sets of high-precision sliders are evenly distributed around the mold cavity. The sliders are driven by servo motors. The outer contour of the valve body core is controlled by the radial movement of the sliders. At the same time, the positioning effect of the center column is used to ensure that the coaxiality of the inner hole is ≤0.03mm. During the secondary injection molding stage, the inner hole of the valve body core is used as the positioning reference, and clearance fit is used to achieve the positioning connection between the valve body core and the secondary mold. The form and position tolerance of the valve body shell is controlled by the uniformity of the mold temperature field. Preferably, the center column is made of mold steel with a hardness ≥HRC55, the surface of the column is precision ground, the cylindricity error is ≤0.005mm, and the surface roughness Ra is ≤0.1μm; the center column and the valve plate are connected by a combination of locating pins and bolts, and the locating pin diameter tolerance band is H7 / g6. Preferably, the slider system for the first injection molding includes a guide mechanism, a pressure sensor and a displacement feedback device. The guide mechanism adopts a ball guide rail, the pressure sensor monitors the slider injection pressure in real time, and the displacement feedback device forms a closed-loop control with the injection molding machine control system. Preferably, the first injection molding process parameters are set as follows: injection pressure 90-110 MPa, melt temperature 220-240° C., a circulating oil cooling system is used in the cooling stage, and the cooling time is set to 12-18 seconds according to the valve body core wall thickness. Preferably, the magnetic flux tube is a hollow cylinder made of a soft magnetic alloy material, the outer diameter has a matching tolerance of H8 / h7 with the valve body core positioning hole, and the length direction exceeds the end face of the positioning hole by 2-5 mm; The electromagnetic positioning device of the secondary injection mold includes 6 groups of evenly distributed electromagnetic coils, which are supplied with stable DC current through a thyristor rectifier. Preferably, the positioning pin during secondary injection molding adopts a combined structure of conical and cylindrical surfaces, the conical surface angle of 15°±1° is used for initial guidance, and the cylindrical surface length of 5-10mm is used for precise positioning; the positioning pin material is cemented carbide, and the surface is PVD-treated to form a diamond-like coating with a thickness of 5-8μm.

[0022] Preferably, the secondary injection molding process parameters are set as follows: injection pressure 110-140 MPa, melt temperature 240-270° C., segmented cooling method, and total cooling time 25-35 seconds.

[0023] Preferably, the mold is processed using a five-axis CNC machine tool, the cavity surface is precisely processed by electric spark machining and then ground and polished, with a roughness of Ra≤0.2μm, and the core part is processed by wire cutting.

[0024] In this embodiment, the center positioning system uses the valve plate as a reference carrier, establishing a spatial positioning reference through the center column, and unifying the size and position reference of the initial injection molding. Implementation logic: The valve plate is made of 6061-T6 aluminum alloy (lightweight and rigid), and a φ10mm process hole is machined in the geometric center of the valve plate (serving as a reference axis carrier). The center column is made of Cr12MoV mold steel (HRC58, wear-resistant and deformation-resistant), machined into a φ10mm cylinder, and connected to the valve plate process hole via a locating pin (φ10H7 / g6) and M6 bolt. The locating pin tolerances are: hole H7 (+0.033 / 0), axis g6 (-0.007 / -0.028), and the fitting clearance is 0.007-0.061mm to ensure coaxial adjustment margin. Three-coordinate calibration: Use Zeiss CONTURAG3 three-coordinate measuring machine to scan the center column busbar (5 sections, 20 points each section). The coaxiality of the fitting axis and the axis of the valve plate process hole is ≤0.01mm (achieved by adjusting the bolt preload + gasket fine-tuning).

[0025] In this embodiment, the primary injection datum surface (top surface of the center column) is the machined surface at the top of the center column. It serves as the positioning reference for the initial injection mold and must be parallel to the fixed platen of the injection molding machine. The top surface of the center column is precision-grinded to a flatness of ≤0.005mm and a surface roughness of Ra ≤0.1μm. Parallelism testing: A Renishaw XL-80 laser interferometer is used to measure the parallelism between the datum surface and the fixed platen of the injection molding machine (which secures the target mirror via a magnetic mount). The error is ≤0.02mm (for a fixed platen length of 500mm, the maximum allowable deviation is 0.01mm).

[0026] In this embodiment, the overmolding base (valve core inner hole + magnetic flux tube) is a hollow cylinder made of a soft magnetic alloy (1J50 iron-nickel alloy, magnetic permeability μ ≥ 8000 H / m). It provides magnetic constraint and positioning for the valve core. The valve core has a pre-set φ20mm positioning hole. The magnetic flux tube has an outer diameter of φ20H8 (+0.033 / 0), which matches the positioning hole h7 (-0.021 / 0). Its length is 22mm (the positioning hole is 17mm deep, with a 5mm overhang), ensuring positioning stability.

[0027] Electromagnetic positioning device: 6 groups of enameled wire coils (wire diameter φ0.5mm, number of turns 1200 turns) are evenly distributed around the mold. A 10A DC current (current fluctuation ≤1%) is provided by a KK100A thyristor rectifier to generate a 0.4T magnetic field, which attracts the magnetic flux tube to achieve suspended positioning of the valve body core (offset ≤0.005mm).

[0028] In this embodiment, the first injection molding slider system features four high-precision sliders (SKD61 material, HRC52), driven by a Panasonic A6 servo motor (rated torque 2 N·m, positioning accuracy ±0.005 mm). Closed-loop control components include a guide mechanism: a THKSR20 ball guide (straightness ≤ 0.01 mm / m, load capacity 5 kN) ensures the radial movement accuracy of the sliders. A pressure sensor: an HBMC16 pressure sensor (range 0-200 MPa, accuracy 0.1% FS) monitors slider forces during injection molding in real time and provides feedback to the injection molding machine PLC. A Heidenhain LC183 linear scale (resolution 0.001 mm) forms a closed loop with the servo motor, dynamically adjusting the slider position and controlling the valve core's outer contour to ±0.02 mm.

[0029] In this embodiment, the first injection molding process parameters are: Injection pressure: 90~110MPa (for PA66+30%GF material, optimized through Moldflow simulation: 90MPa in the filling stage and 110MPa in the holding stage).

[0030] Melt temperature: 220~240℃ (real-time monitoring by infrared thermometer, error ±3℃).

[0031] Circulating oil cooling system: using a water temperature controller (set at 25°C) + spiral cooling water channel (diameter φ8mm, spacing 20mm), cooling time 15 seconds (when the valve body core wall thickness is 2mm, verify that the core temperature difference is ≤5°C using a thermal imager).

[0032] In this embodiment, the mold processing technology is as follows: Five-axis machining: Using the DMG DMU80 machine tool (positioning accuracy ±0.002mm) to process the complex curved surfaces of the mold cavity (such as the streamlined contour of the valve body shell).

[0033] Electric spark + grinding and polishing: Electrospark machining: Using Makino ED3 electrospark machine, copper male electrode (accuracy ±0.003mm), the surface roughness of the machining cavity is Ra≤0.8μm.

[0034] Grinding and polishing: Use elastic grinding head + diamond grinding paste (W5 particle size) to polish to Ra≤0.2μm and eliminate discharge marks.

[0035] Wire-cut EDM: Sodick ALN400 machine tool, for machining precise grooves on cores (such as the flow channel grooves on valve body cores), with an accuracy of ±0.003mm.

[0036] In this embodiment, the secondary injection molded positioning pin: Structural design: Made of YG8 cemented carbide, with a 15°±1° conical surface at the front end (guide section, 3mm length) and a φ8mm cylindrical surface at the rear end (positioning section, 8mm length).

[0037] Surface treatment: PVD deposited 6μm diamond-like carbon coating (DLC), hardness HV ≥ 2000, friction coefficient ≤ 0.15, reducing positioning wear (lifespan increased by 3 times).

[0038] In this embodiment, the secondary injection molding is cooled in sections: process logic: the mold temperature is 60°C in the first 10 seconds (to accelerate melt filling and avoid short shots), and the mold temperature is 40°C in the last 20 seconds (to quickly cool and set the shape and control shrinkage).

[0039] The mold temperature controller is controlled by zones (2 sets of heaters + 2 sets of cooling circuits), with real-time temperature feedback through thermocouples to adjust the water flow (accuracy ±1L / min).

[0040] The beneficial effects of the above technical solution are: through the coordination of reference chain construction, processing closed-loop control, and mold ultra-precision manufacturing, the coaxiality of the valve body core inner hole is ≤0.03mm, the coaxiality of the valve body shell and the core is ≤0.05mm, and the parallelism is ≤0.03mm, which meets the IT6 level form and position tolerance requirements of the gearbox solenoid valve, and the solenoid valve response time fluctuation is ≤±20ms (original process ±50ms), the gear shifting frustration is reduced by 70%, the hydraulic oil leakage is ≤0.5mL / h (original process ≥2mL / h), energy consumption is reduced by 12%, and reliability is improved by 150%. That is, the deep integration of magnetic constraint positioning, servo closed-loop control, and multi-physical field simulation breaks through the bottleneck of reliance on traditional injection molding experience and supports the precision manufacturing needs of high-end gearboxes.

[0041] The present invention provides an injection molding process for a gearbox proportional solenoid valve body, adopts CAD / CAM integrated technology for process design, establishes a three-dimensional parameterized model including a valve body core and a shell, and adopts tetrahedron units for finite element meshing; Set a multi-objective optimization function for each grid cell , including filling balance F1, pressure gradient F2, and temperature uniformity F3;

[0042]

[0043]

[0044] in, is the pressure difference between the flow channel inlet and the cavity end under the corresponding grid unit; is the total length of the flow channel under the corresponding grid unit; is the dynamic viscosity of the melt; is the melt flow rate under the corresponding grid unit; 、 、 is the weight coefficient; Indicates the maximum pressure difference per unit length; They represent the maximum balance, minimum balance, and average balance of the cavity corresponding to the grid unit; T Respectively represent the maximum temperature, minimum temperature and average temperature of the melt; The gate coordinates and diameter are used as decision variables, and the constraint condition is that the distance between the gate and the parting surface is ≥3mm. The genetic algorithm is used to preliminarily determine the gate position. By iterative calculation, the objective function of all grid cells The initially determined gate position is converged to the global minimum to determine the final gate position.

[0045] In this embodiment, F1 constrains the filling time difference at the end of the cavities to ≤15%, ensuring that the melt reaches the end of each cavity simultaneously. This improves the filling integrity of the valve core runner from 95% to 99.5%, reduces the short shot defect rate by 60%, and reduces the flash thickness caused by over-injection from 0.1mm to 0.03mm, reducing subsequent deburring costs by 40%.

[0046] By limiting the pressure drop per unit length to ≤0.05 MPa / mm, F2 prevents plastic deformation of the mold due to high pressure. This reduces mold cavity wear by 40%, extending the maintenance cycle from 50,000 to 80,000 cycles, and reducing the load on the injection molding machine's hydraulic system by 25%, thereby reducing energy consumption by 18%.

[0047] By constraining the melt front temperature difference to ≤8% through F3, warping caused by uneven cooling shrinkage is eliminated. The flatness of the valve body shell is optimized from 0.08mm to 0.03mm, meeting the IT6 level form and position tolerance of the solenoid valve. Linear shrinkage fluctuations are reduced from 1.2% to 0.5%, and dimensional accuracy is stabilized at ±0.015mm.

[0048] The genetic algorithm traverses the 4-dimensional solution space of gate coordinates (x, y, z) + diameter (d), replacing the traditional "mold trial-mold repair" cycle.

[0049] Through multi-objective optimization, the core indicators of the valve body have achieved a leap: coaxiality: ≤0.03mm (traditional process 0.08mm), ensuring the stability of the fitting clearance between the valve core and the valve body; response time: fluctuation ≤±15ms (traditional ±50ms), eliminating gear shifting jerks; leakage: reduced by 70%, and the efficiency of the hydraulic system increased by 12%.

[0050] The beneficial effect of the above technical solution is: building a closed loop of design-simulation-optimization-production, providing a replicable digital solution for the mass production of high-precision transmission valve bodies.

[0051] The present invention provides an injection molding process for a gearbox proportional solenoid valve body. The online detection system includes a non-contact laser probe and a machine vision device, which detects the aperture and outer contour dimensions of the valve body core and the form and position tolerances of the valve body shell in real time. The detection data is transmitted to a PLC control system in real time via industrial Ethernet, triggering automatic adjustment of injection molding parameters to form a dynamic compensation mechanism for processing accuracy.

[0052] The non-contact laser probe is based on the principle of laser triangulation. It emits a laser beam, receives reflected light from the object being measured, and calculates the angular offset of the beam to obtain three-dimensional coordinate data. The Optiv 1220 laser probe has a measurement accuracy of ±0.003mm and a scanning speed of 2000 points / second. Measurement logic: Aperture detection: 32 points are scanned along the circumference of the valve core inner hole to fit the roundness error (e.g., actual aperture φ15.002mm, tolerance ±0.005mm). Contour detection: A spiral scan of the valve core outer contour generates point cloud data, which is compared with the CAD model to check the boss height (e.g., design value 8.00mm, measured value 7.995mm).

[0053] In this embodiment, the machine vision device uses an industrial camera to capture images and, combined with image processing algorithms, analyzes the valve body's surface features and form and position tolerances. Hardware Configuration: Camera: Keyence CV-X series smart camera, 2048×2048 pixel resolution. Light Source: Ring LED light source (525nm wavelength, ≥95% uniformity), eliminating reflection interference.

[0054] Detection content: Geometric tolerance: Use edge extraction algorithm to detect the verticality of the valve body shell (such as design requirement ≤ 0.03mm, actual measurement 0.025mm). Surface defects: Use template matching algorithm to identify defects such as flash and missing materials (such as threshold setting: area > Defect alarm).

[0055] In this embodiment, industrial Ethernet is a high-speed industrial communication protocol based on the IEEE802.3 standard, which enables real-time data transmission between devices.

[0056] In this embodiment, during the data acquisition phase, after the first injection molding, the robot grabs the valve body core to the inspection station (positioning repeatability accuracy ±0.01mm); the laser probe completes the scanning of the inner hole and outer contour within 5 seconds, and the machine vision device simultaneously detects the form and position tolerances.

[0057] Closed-loop control logic is used in the parameter adjustment stage: Aperture compensation: If the aperture is detected to be 0.002mm smaller, the PLC output instruction will reduce the radial displacement of the slider by 0.002mm; Pressure compensation: If the roundness error exceeds the tolerance (actual measurement 0.006mm>threshold 0.005mm), the next injection pressure will be reduced by 1MPa.

[0058] A verification mechanism is used in the execution feedback phase: the first product produced after adjustment is tested again to confirm the compensation effect (such as the aperture is corrected from 15.002mm to 15.000mm); after the data is stable for three consecutive tests, the system enters normal monitoring mode.

[0059] The beneficial effects of the above technical solution are: through real-time detection and dynamic compensation, traditional post-inspection is transformed into real-time prevention, breaking through the accuracy bottleneck of the injection molding process and supporting the precision manufacturing needs of high-end transmission solenoid valves.

[0060] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An injection molding process for a gearbox proportional solenoid valve body, characterized in that: include: Reference selection: During the first injection molding, a center positioning system is constructed using the valve plate as a carrier. A cylindrical center column is fixed to the geometric center of the valve plate. The coaxiality error between the center column axis and the valve plate reference axis is calibrated using a three-coordinate measuring machine to ≤0.01mm. The top end face of the center column is used as the reference surface for the first injection molding. The parallelism error between the reference surface and the fixed plate of the injection molding machine is within 0.02mm. During secondary injection molding, the valve body core molded by the first injection molding is used as the reference workpiece, and a magnetic flux tube is embedded in the preset positioning hole of the valve body core. The inner hole axis of the valve body core is used as the reference axis of the secondary injection molding. Processing control: During the first injection molding stage, four sets of high-precision sliders are evenly distributed around the mold cavity. The sliders are driven by servo motors. The outer contour of the valve body core is controlled by the radial movement of the sliders. At the same time, the positioning effect of the center column is used to ensure that the coaxiality of the inner hole is ≤0.03mm. During the secondary injection molding stage, the inner hole of the valve body core is used as the positioning reference, and clearance fit is used to achieve the positioning connection between the valve body core and the secondary mold. The form and position tolerance of the valve body shell is controlled by the uniformity of the mold temperature field.

2. The injection molding process for the transmission proportional solenoid valve body according to claim 1, characterized in that: The center column is made of mold steel with a hardness of ≥HRC55, and the surface of the column is precision ground, with a cylindricity error of ≤0.005mm and a surface roughness Ra≤0.1μm; the center column and the valve plate are connected in a combination of locating pins and bolts, and the locating pin diameter tolerance range is H7 / g6.

3. The injection molding process for the transmission proportional solenoid valve body according to claim 1, characterized in that: The slider system for the first injection molding includes a guide mechanism, a pressure sensor and a displacement feedback device. The guide mechanism adopts a ball guide rail, the pressure sensor monitors the slider injection molding pressure in real time, and the displacement feedback device forms a closed-loop control with the injection molding machine control system.

4. The injection molding process for the transmission proportional solenoid valve body according to claim 3, characterized in that: The process parameters for the first injection molding are set as follows: injection pressure 90-110 MPa, melt temperature 220-240°C, a circulating oil cooling system is used in the cooling stage, and the cooling time is set to 12-18 seconds according to the wall thickness of the valve body core.

5. The injection molding process for the transmission proportional solenoid valve body according to claim 1, characterized in that: The magnetic flux tube is a hollow cylinder made of soft magnetic alloy material, the outer diameter of which has a matching tolerance of H8 / h7 with the positioning hole of the valve body core, and the length direction exceeds the end face of the positioning hole by 2-5mm; The electromagnetic positioning device of the secondary injection mold includes 6 groups of evenly distributed electromagnetic coils, which are supplied with stable DC current through a thyristor rectifier.

6. The injection molding process for the transmission proportional solenoid valve body according to claim 5, characterized in that: The positioning pins used in secondary injection molding use a combination of conical and cylindrical surfaces. The conical surface angle of 15°±1° is used for initial guidance, and the cylindrical surface length of 5-10mm is used for precise positioning. The positioning pins are made of cemented carbide, and the surface is PVD-treated to form a diamond-like coating with a thickness of 5-8μm.

7. The injection molding process for the transmission proportional solenoid valve body according to claim 1, characterized in that: The secondary injection molding process parameters are set as follows: injection pressure 110-140 MPa, melt temperature 240-270°C, segmented cooling method, and total cooling time 25-35 seconds.

8. The injection molding process for the transmission proportional solenoid valve body according to claim 1, characterized in that: CAD / CAM integrated technology was used for process design, a three-dimensional parametric model including the valve core and shell was established, and tetrahedron units were used for finite element meshing; Set a multi-objective optimization function for each grid cell , including filling balance F1, pressure gradient F2, and temperature uniformity F3; in, is the pressure difference between the flow channel inlet and the cavity end under the corresponding grid unit; is the total length of the flow channel under the corresponding grid unit; is the dynamic viscosity of the melt; is the melt flow rate under the corresponding grid unit; 、 、 is the weight coefficient; Indicates the maximum pressure difference per unit length; They represent the maximum balance, minimum balance, and average balance of the cavity corresponding to the grid unit; T Respectively represent the maximum temperature, minimum temperature and average temperature of the melt; The gate coordinates and diameter are used as decision variables, and the constraint condition is that the distance between the gate and the parting surface is ≥3mm. The genetic algorithm is used to preliminarily determine the gate position. By iterative calculation, the objective function of all grid cells The initially determined gate position is converged to the global minimum to determine the final gate position.

9. The injection molding process for the transmission proportional solenoid valve body according to claim 8, characterized in that: The mold is processed by a five-axis CNC machine tool. The cavity surface is precisely processed by electric spark and then ground and polished. The roughness Ra is ≤ 0.2μm. The core part is processed by wire cutting.

10. The injection molding process for the transmission proportional solenoid valve body according to claim 1, characterized in that: The online detection system includes a non-contact laser probe and a machine vision device to detect the aperture and outer contour dimensions of the valve body core and the form and position tolerances of the valve body shell in real time; the detection data is transmitted to the PLC control system in real time via industrial Ethernet, triggering automatic adjustment of the injection molding parameters to form a dynamic compensation mechanism for processing accuracy.

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