Production and processing method of high-precision wood pattern for automobile ornament

Abstract

The invention discloses a production and processing method of a high-precision wood mold for an automobile ornament, relates to the technical field of automobile mold manufacturing, and aims to solve the technical problems that a traditional automobile ornament wood mold is low in dimensional precision, poor in surface quality, insufficient in dimensional stability and difficult to adapt to a complex curved surface and assembly requirements of the automobile ornament. According to the method, accurate matching and performance optimization of the wood pattern and the automobile ornament are achieved through four-stage innovation of modification of the special wood for the automobile ornament, digital structure adaptive design, multi-procedure collaborative forming and functional post-treatment. According to the wood mold machined through the method, the dimensional tolerance is smaller than or equal to + / -0.05 mm, the surface roughness Ra is smaller than or equal to 1.6 micrometers, the moisture content is stabilized to be 8%-12%, the bending deformation is smaller than or equal to 0.2 mm / m, the wood mold is suitable for forming of complex structures of automobile interior and exterior ornaments, and the service life is obviously prolonged compared with a traditional wood mold.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile processing die manufacturing, in particular to a high-precision wood die production and processing method for automobile trim parts, which is suitable for the preparation of forming dies of automobile interior and exterior trim parts such as instrument panels, door panels, column trim parts, and bumpers. BACKGROUND

[0002] As an important type of die for forming automobile trim parts, wood die is widely used in the research and development and small-batch production of automobile trim parts due to its advantages such as flexible processing, controllable cost, and short forming cycle. However, automobile trim parts usually have complex curved surfaces, precise assembly gaps, and high surface quality requirements, and the traditional wood die production and processing method has many technical bottlenecks:

[0003] Poor performance compatibility of wood base material: ordinary wood has strong hygroscopicity and insufficient dimensional stability, and after traditional treatment, it is still prone to deformation and cracking due to changes in environmental humidity, which reduces the size matching accuracy of the wood die and the automobile trim part, affecting the assembly effect of the trim part;

[0004] Lack of targeted structure design: without combining the curved surface characteristics and assembly requirements of automobile trim parts, the parting surface of the wood die is unreasonable and the exhaust passage is improperly arranged, which easily leads to defects such as flash and bubbles after the trim part is formed;

[0005] Insufficient processing precision and surface quality: traditional processing methods cannot accurately reproduce the complex curved surfaces of automobile trim parts, and the dimensional tolerance is usually controlled to be more than ±0.5mm, with high surface roughness, which cannot meet the appearance and assembly requirements of automobile trim parts;

[0006] Short service life: the natural defects of wood and the processing internal stress are not effectively eliminated, combined with the repeated contact with the forming material during the forming process of the automobile trim part, the wood die is easily worn and corroded, and the service life is usually not more than 300 forming cycles, increasing the production cost and the frequency of die replacement.

[0007] Although existing technologies attempt to introduce numerical control processing to improve precision, they do not optimize the modification of wood, structure design, and post-processing in coordination with the special requirements of automobile trim parts, resulting in the inability of the wood die to meet the high-precision forming requirements of automobile trim parts in terms of adaptability, stability, and service life. Therefore, it is of great technical value and industrial significance to develop a wood die production and processing method that has special adaptability to automobile trim parts, high precision, and long service life. SUMMARY

[0008] The purpose of the present application is to overcome the shortcomings of the prior art, provide a high-precision wood mold production and processing method for automobile ornaments, through four-stage collaborative innovation of special wood modification for automobile ornaments, digital adaptive design, multi-process collaborative forming and functional post-processing, the performance of the base material, structure adaptation, processing precision and use performance are optimized in all dimensions, solving the technical problems of poor adaptability, low precision and short service life of traditional wood molds, and obtaining a wood mold that meets the requirements of complex structure and high precision of automobile ornaments. The specific technical scheme is as follows:

[0009] A high-precision wood mold production and processing method for automobile ornaments, comprising the following steps:

[0010] S1, special wood modification for automobile ornaments: selecting hardwoods that adapt to the forming requirements of automobile ornaments, after cutting, gradient drying, degreasing treatment, using vacuum pressure impregnation modification process, composite modifier is penetrated into the wood, after curing treatment, modified wood blank with size stability≥95% is obtained;

[0011] S2, digital design for automobile ornament adaptive type: based on the three-dimensional model of automobile ornaments, combined with the assembly gap and forming process requirements, the wood mold structure optimization design is carried out, the processing area of the adaptive automobile ornament surface is divided, the collaborative processing sequence is planned, and the adaptive numerical control processing path is generated;

[0012] S3, multi-process collaborative forming processing: the modified wood blank is fixed on the numerical control machining equipment, and the rough machining, stress release treatment, semi-finishing, surface pretreatment and finishing are carried out in turn, online size detection and error compensation are implemented during the processing to ensure the size adaptability of the wood mold and the automobile ornament;

[0013] S4, special post-processing for automobile ornaments: surface hardening and waterproof and corrosion resistant composite treatment are carried out on the finished wood mold, after constant temperature and humidity curing, the adaptive precision of the wood mold and the automobile ornament is verified through full-size detection, and the high-precision wood mold for automobile ornaments is obtained after passing the test.

[0014] Preferably, the hardwood in step S1 is one of birch, beech, maple or oak, and the wood density is 0.6-0.8g / cm³; after cutting, the wood blank size is reserved 10-15mm processing allowance compared with the target wood mold size.

[0015] Preferably, the gradient drying treatment conditions in step S1 are: temperature 60-80℃, humidity 40-60%, drying time 48-72h, and water content≤15% after drying; the degreasing treatment adopts high temperature steam degreasing method, temperature 100-120℃, time 2-4h.

[0016] Preferably, the composite modifier in the step S1 is a compounded system of epoxy resin and polyethylene glycol, the mass ratio of the compound is (3-5):1, the solid content of the modifier is 30-50%; the vacuum pressure impregnation process parameters are: vacuum degree-0.08~-0.095MPa, impregnation time 1-2h, pressure 0.3-0.6MPa, pressure time 2-3h; the curing treatment conditions are: temperature 80-100℃, time 4-6h.

[0017] Preferably, the structure optimization design in the step S2 includes: the parting surface design, the curved surface transition optimization, the exhaust passage arrangement and the stiffening rib strengthening design which are adapted to the assembly requirements of the automobile trim; the numerical control machining path adopts the layered milling and the constant height milling composite mode, and is adapted to the complex curved surface forming demand of the automobile trim.

[0018] Preferably, the numerical control machining equipment in the step S3 is a numerical control milling machine which is adapted to the complex structure machining of the automobile trim; the stress release treatment conditions after rough machining are: temperature 40-50℃, humidity 50-60%, holding time 12-24h; the surface pretreatment adopts the sandpaper with 180-240 meshes for polishing treatment.

[0019] Preferably, the online size detection in the step S3 adopts a laser measuring head, the detection accuracy is less than or equal to ±0.01mm, the key assembly surface and the curved surface profile of the automobile trim are detected, and error compensation is carried out in real time after detection.

[0020] Preferably, the surface hardening treatment in the step S4 adopts polyurethane varnish spraying, the spraying thickness is 0.1-0.3mm, the curing temperature is 60-80℃, and the time is 2-3h; the waterproof and corrosion-resistant treatment adopts a compounded system of silane waterproof agent and boride corrosion inhibitor, and is brushed 2-3 times, and the interval is 1-2h.

[0021] Preferably, the constant temperature and humidity curing conditions in the step S4 are: temperature 20-25℃, humidity 50-60%, curing time 24-48h; the full-size detection adopts a laser three-dimensional scanner, the scanning covers all forming surfaces of the wooden mold of the automobile trim, and the scanning accuracy is less than or equal to ±0.02mm.

[0022] Compared with the prior art, the present application has the following remarkable creative beneficial effects:

[0023] The automobile trim has high special adaptation: from wood modification, structure design to processing technology, the complex curved surface, assembly requirements and forming characteristics of the automobile trim are specially optimized, the size adaptation accuracy of the wooden mold and the automobile trim is high, the problems such as flash, bubble and assembly failure in the trim forming process can be effectively avoided, and the forming requirements of various interior and exterior trims such as automobile instrument panel, door panel and bumper can be adapted;

[0024] Precision and stability leapfrog: through wood modification and digital adaptive design, the wood mold size tolerance is controlled within ±0.05mm, the surface roughness Ra≤1.6μm, the moisture content is stable at 8-12%, the bending deformation is ≤0.2mm / m, which is more than 10 times higher than the traditional automobile trim wood mold precision, and the size stability is improved by 60%, ensuring the consistency of the trim forming quality;

[0025] Significant extension of service life: with the help of composite modification, stress release and waterproof and corrosion resistant composite treatment, the service life of the wood mold is ≥500 times of forming cycle, which is more than 60% higher than the traditional automobile trim wood mold, reducing the mold replacement frequency and production cost, and adapting to the needs of small to medium batch production of automobile trim; DETAILED DESCRIPTION

[0026] A high-precision wood mold production and processing method for automobile trim, comprising the following steps:

[0027] S1, special wood modification treatment for automobile trim

[0028] Base material selection and basic treatment: select hardwood (birch, beech, etc.) with a density of 0.6-0.8g / cm³, which has dense texture and stable mechanical properties, suitable for the forming requirements of automobile trim wood mold; cut the logs into wood blanks with a processing allowance of 10-15mm larger than the target wood mold size to avoid precision defects caused by insufficient processing allowance; use gradient drying process (temperature 60-80℃, humidity 40-60%, time 48-72h) to accurately control the moisture content of the wood blank to ≤15%, reducing deformation caused by drying stress; use high-temperature steam degreasing method (temperature 100-120℃, time 2-4h) to remove internal oil in the wood, reducing the risk of affecting the quality of the trim in the subsequent forming process due to oil separation.

[0029] Vacuum pressure impregnation modification: in view of the size stability requirements of automobile trim wood mold, an innovative composite modifier (mass ratio 3-5:1, solid content 30-50%) of epoxy resin and polyethylene glycol is used, which can improve the hardness and wear resistance of wood, and polyethylene glycol can improve the toughness and size stability of wood, and the two work together to optimize the performance of wood; through vacuum pressure impregnation process, first impregnate at -0.08~-0.095MPa vacuum for 1-2h to extract the air in the wood, ensuring that the modifier penetrates into the wood pores, then apply 0.3-0.6MPa pressure for 2-3h to strengthen the combination of the modifier and wood fibers; finally, cure at 80-100℃ for 4-6h to form a three-dimensional cross-linked network of the modifier in the wood, improving the size stability of the wood to ≥95%, fundamentally solving the problem of traditional wood deformation and cracking, and adapting to the long-term forming requirements of automobile trim.

[0030] 2. Digital design of automotive trim fitting adaptation

[0031] Special structure optimization design: based on the three-dimensional model of automotive trim, combined with the assembly gap of trim, the flow characteristics of forming material, the special structure of wood mold is designed: optimize the parting surface to ensure that the trim is demolded smoothly after forming and without flash; transition optimization is performed for the complex curved surface of the automotive trim to avoid stress concentration caused by sharp corners; according to the exhaust requirement of the forming material, the exhaust passage is reasonably arranged to prevent defects such as bubbles and material defects during the forming process of the trim; add stiffening ribs to strengthen the rigidity of the wood mold structure to avoid deformation of the wood mold during use and ensure the consistency of the forming precision of the trim.

[0032] Adaptive machining path planning: use CAD / CAM software to generate numerical control machining path, adopt layered milling and isometric milling composite mode for the complex curved surface features of automotive trim to adapt to the precise forming of curved surface profile; adjust the machining path according to the wood grain direction to reduce the internal stress generated during machining, avoid machining cracks on the wood mold, ensure the surface quality and dimensional accuracy of the wood mold, and realize the precise matching of the wood mold and the automotive trim.

[0033] 3. Multi-process collaborative forming processing

[0034] Numerical control collaborative processing: fix the modified wood blank on the numerical control milling machine suitable for the complex structure processing of automotive trim, and sequentially perform rough machining, semi-finish machining, and finish machining, each process is smooth, avoiding the loss of precision caused by process conversion in traditional processing; rough machining quickly removes excess material to lay a foundation for subsequent precision machining; semi-finish machining corrects the rough machining error and optimizes the curved surface profile; finish machining realizes the precise replication of the wood mold forming surface to meet the size and surface requirements of the automotive trim.

[0035] Stress release and online detection collaboration: after rough machining, timely stress release treatment (temperature 40-50℃, humidity 50-60%, incubation for 12-24h) is performed to effectively eliminate the internal stress generated during processing and avoid accumulation of internal stress leading to subsequent deformation of the wood mold; after semi-finish machining, 180-240 mesh sandpaper is used for surface pretreatment to remove machining marks and improve the surface quality of finish machining; during processing, laser probes are used for online size detection (accuracy ≤±0.01mm) for key assembly surfaces and curved surface profiles of automotive trim to real-time feedback size error and compensation, ensuring that the dimensional accuracy of each part of the wood mold meets the assembly requirements of automotive trim and avoiding poor assembly of trim due to dimensional deviation.

[0036] 4. Special post-processing for automotive trim

[0037] Functional composite treatment: According to the use environment of the wood mold in the forming process of the automobile trim part, composite treatment of surface hardening and waterproofing and corrosion prevention is carried out: surface hardening is carried out by spraying polyurethane varnish, the spraying thickness is 0.1-0.3mm, and the surface hardness and wear resistance of the wood mold are improved by curing at 60-80℃ for 2-3h, and the friction loss of the wood mold with the trim part material in the forming process is reduced; waterproofing and corrosion prevention treatment is carried out by using a compounded system of silane waterproofing agent and boride corrosion inhibitor, and the wood mold is brushed 2-3 times (with an interval of 1-2h each time), the silane waterproofing agent can form a hydrophobic film on the surface of the wood mold to prevent water from penetrating into the wood during the forming process, and the boride corrosion inhibitor can effectively inhibit the erosion of mold by mold, prolong the service life of the wood mold, and meet the needs of batch forming of automobile trim parts.

[0038] Constant temperature and humidity curing and full-size detection: the treated wood mold is cured in an environment with a temperature of 20-25℃ and a humidity of 50-60% for 24-48h, so that the water content of the wood mold is stabilized at 8-12%, and the performance of the wood mold is stable; full-size detection is carried out by using a laser three-dimensional scanner, the scanning covers all the forming surfaces of the wood mold, the scanning accuracy is ≤±0.02mm, the fitting accuracy of the wood mold and the automobile trim part is verified, and the size tolerance of the wood mold is ensured to be ≤±0.05mm, and the surface roughness Ra is ≤1.6μm, so that the wood mold with high precision for automobile trim parts is qualified.

[0039] Example 1 (wood mold for automobile door panel trim part)

[0040] Special wood modification treatment for automobile trim parts: select beech with a density of 0.7g / cm³, cut into wood blanks with a reserved processing allowance of 12mm; dry at 70℃ and a humidity of 50% for 60h, so that the water content is reduced to 13%; degrease by high-temperature steam at 110℃ for 3h; prepare a composite modifier (solid content 40%) according to the mass ratio of epoxy resin to polyethylene glycol 4:1, immerse at a vacuum degree of-0.09MPa for 1.5h, immerse at a pressure of 0.4MPa for 2.5h, and then cure at 90℃ for 5h, so that the modified wood blank with a dimensional stability of 96% is obtained.

[0041] Digital design suitable for automobile trim parts: based on the three-dimensional model of the automobile door panel trim part, the parting surface and the curved surface transition are optimized, three exhaust channels are arranged, and two stiffening ribs are added; the machining path is generated by using CAM software, and the composite mode of layered milling and equal-height milling is adopted to adapt to the curved profile of the door panel trim part.

[0042] Multi-process collaborative forming processing: the modified wood blank is fixed on the numerical control milling machine, and rough machining, semi-finishing and finishing are carried out in sequence; after rough machining, stress release is carried out at 45℃ and a humidity of 55% for 18h; after semi-finishing, sandpaper with a mesh size of 200 is used for polishing; during the processing, the installation hole position and the edge profile of the door panel trim part are detected and error compensated on line by using a laser measuring head.

[0043] Special post-treatment for automobile trim parts: spraying 0.2 mm thick polyurethane varnish, curing at 70 °C for 2.5 h; brushing 3 times of the compounded system of silane waterproof agent and boride corrosion inhibitor, with an interval of 1.5 h; curing at 22 °C and 55% humidity for 36 h; the laser three-dimensional scanner detection shows that the wood mold size tolerance is ±0.04 mm, the surface roughness is Ra 1.2 μm, and the water content is 10%.

[0044] Through use verification, the wood mold bending deformation amount is 0.15 mm / m, the service life reaches 580 times of forming cycle, the formed automobile door panel trim part has smooth surface and accurate size, and the assembly gap meets the design requirements.

[0045] Example 2 (wood mold for automobile bumper trim part)

[0046] Special wood modification treatment for automobile trim parts: birch with a density of 0.65 g / cm³ is selected and cut into wood blanks with a reserved 15 mm processing allowance; drying at 65 °C and 45% humidity for 50 h, the water content is reduced to 12%; high-temperature steam degreasing at 105 °C for 2.5 h; a composite modifier (solid content 35%) is prepared according to the mass ratio of epoxy resin to polyethylene glycol 3:1, impregnated at a vacuum degree of-0.085 MPa for 1.2 h, impregnated at a pressure of 0.35 MPa for 2 h, and then cured at 85 °C for 4.5 h to obtain modified wood blanks with a size stability of 95%.

[0047] Digital design suitable for automobile trim parts: based on the three-dimensional model of the automobile bumper trim part, the parting surface is optimized to adapt to the arc structure of the bumper, 5 exhaust channels are arranged, and 3 stiffening ribs are added; the processing path suitable for the complex curved surface of the bumper is planned to reduce the internal stress during processing.

[0048] Multi-process collaborative forming processing: multi-process processing is carried out by using a numerical control milling machine, stress release at 42 °C and 52% humidity for 15 h after rough machining; sanding with 240 mesh sandpaper after semi-finishing; online detection and error compensation are carried out for the installation buckle position and curved surface profile of the bumper.

[0049] Special post-treatment for automobile trim parts: spraying 0.15 mm thick polyurethane varnish, curing at 65 °C for 2 h; brushing 2 times of the compounded system of waterproof and corrosion resistant, with an interval of 2 h; curing at 23 °C and 53% humidity for 40 h; full-size detection shows that the wood mold size tolerance is ±0.03 mm, the surface roughness is Ra 1.0 μm, and the water content is 9%.

[0050] Through use verification, the wood mold bending deformation amount is 0.12 mm / m, the service life reaches 620 times of forming cycle, the formed automobile bumper trim part has high size precision and no bubble defects, meeting the batch production requirements.

[0051] The above examples are only used for illustrating the technical solutions of the present application, and are not intended to limit the present application. Without departing from the principles and innovative concepts of the present application, the adjustment and optimization of material selection, process parameters and the like by those skilled in the art should be considered as falling within the protection scope of the present application.

Claims

1. A method for producing high-precision wooden molds for automotive trim parts, characterized in that, Includes the following steps: S1. Wood Modification Treatment for Automotive Trim Parts: Select hardwoods suitable for the molding requirements of automotive trim parts, and after cutting, gradient drying and degreasing, use a vacuum pressure impregnation modification process to penetrate the composite modifier into the wood. After curing treatment, obtain modified wood blanks with dimensional stability ≥95%. S2. Adaptive Digital Design for Automotive Trim Parts: Based on the 3D model of automotive trim parts, combined with assembly gaps and molding process requirements, the wooden mold structure is optimized, the processing area for the curved surface of the automotive trim parts is divided, the collaborative processing sequence is planned, and an adaptive CNC machining path is generated. S3. Multi-process collaborative molding and processing: The modified wood blank is fixed on the CNC machining equipment and then subjected to roughing, stress relief treatment, semi-finishing, surface pretreatment and finishing in sequence. Online dimension detection and error compensation are implemented during the processing to ensure the dimensional compatibility between the wood mold and the automotive trim parts. S4. Automotive trim post-processing: The finished wooden mold undergoes surface hardening, waterproofing and anti-corrosion composite treatment, and is then cured under constant temperature and humidity. The fit accuracy between the wooden mold and the automotive trim is verified through full-size testing. Once qualified, a high-precision wooden mold for automotive trim is obtained.

2. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The hardwood mentioned in step S1 is one of birch, beech, maple or oak, with a wood density of 0.6-0.8 g / cm³; after cutting, the size of the wood blank is 10-15 mm larger than the size of the target wood mold.

3. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The gradient drying conditions described in step S1 are: temperature 60-80℃, humidity 40-60%, drying time 48-72h, and moisture content ≤15% after drying; the degreasing treatment adopts high-temperature steam degreasing method, temperature 100-120℃, time 2-4h.

4. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The composite modifier mentioned in step S1 is a compound system of epoxy resin and polyethylene glycol, with a compound mass ratio of (3-5):1 and a solid content of 30-50%; the vacuum pressure impregnation process parameters are: vacuum degree -0.08~-0.095MPa, impregnation time 1-2h, pressure 0.3-0.6MPa, and pressure time 2-3h; the curing conditions are: temperature 80-100℃ and time 4-6h.

5. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The structural optimization design described in step S2 includes: parting surface design adapted to the assembly requirements of automotive trim parts, surface transition optimization, exhaust channel arrangement and stiffening rib reinforcement design; the CNC machining path adopts a composite mode of layered milling and contour milling to adapt to the complex curved surface forming requirements of automotive trim parts.

6. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The CNC machining equipment mentioned in step S3 is a CNC milling machine adapted to the machining of complex automotive trim structures; the stress relief treatment conditions after rough machining are: temperature 40-50℃, humidity 50-60%, and heat preservation time 12-24h; the surface pretreatment is carried out by polishing with 180-240 grit sandpaper.

7. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The online dimensional inspection described in step S3 uses a laser probe with an accuracy of ≤ ±0.01mm. The inspection covers key assembly surfaces and curved contours of automotive trim parts, and error compensation is performed in real time after inspection.

8. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The surface hardening treatment in step S4 is carried out by spraying polyurethane clear varnish with a thickness of 0.1-0.3 mm, a curing temperature of 60-80℃, and a time of 2-3 hours; the waterproof and anti-corrosion treatment is carried out by a compound system of silane waterproofing agent and boride anti-corrosion agent, with 2-3 coats applied and an interval of 1-2 hours between each coat.

9. The method for producing high-precision wooden molds for automotive trim parts according to claim 1, characterized in that, The constant temperature and humidity curing conditions described in step S4 are: temperature 20-25℃, humidity 50-60%, curing time 24-48h; full-size inspection is carried out using a laser 3D scanner, which scans and covers all the molded surfaces of the automotive trim wood mold, with a scanning accuracy of ≤±0.02mm.