Double-color injection molding process method and system for sports water cup

Abstract

The invention relates to the technical field of water cup manufacturing, in particular to a double-color injection molding process method and system for a sports water cup. Comprising the following steps: step 1, primary injection molding: injecting first-color plastic into a first mold cavity, and cooling to crystallization temperature to obtain the sports water cup liner; step 2, primary detection: taking out the inner container of the sports water cup, detecting internal and external temperatures, hardness and surface integrity of the inner container of the sports water cup, and then placing qualified products and defective products in a classified manner; the absolute quality of finished products is guaranteed, defective product defect items and defect degrees can be marked carefully and accurately, available parameters are provided for follow-up rework and follow-up process improvement, the quality of existing finished sports cups is guaranteed, follow-up treatment is facilitated due to accurate classification of unqualified products, and the production efficiency is improved. The waste of raw materials is reduced, and meanwhile, the auxiliary effect on the process improvement is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of water cup manufacturing, and in particular relates to a two-color injection molding process method and system for sports water cups. Background Art

[0002] Nowadays, in the preparation process of plastic sports water bottles, two-color injection molding is increasingly used. This can avoid the problem of single-color injection molding that cannot simultaneously meet the requirements of rigid support and flexible grip, and solve the hidden danger of easy slipping during use.

[0003] After searching, the cited publication number is CN116922692A, with an announcement date of October 24, 2023. The publication is titled "A Sports Water Cup and Its Forming Process," and includes the following steps: Step S1: Clamping the forming mold to form a water cup forming area within the forming mold; Step S2: Injecting a preset volume of plastic material into the water cup forming area through an injection port at the top of the forming mold; Step S3: After the sports water cup is formed, opening the forming mold and removing the sports water cup. The above embodiment can complete the molding of a large number of water cups in a short period of time, meeting the needs of large-scale production and improving production efficiency and capacity. Injection molding can realize complex sealing structure design to ensure the sealing and leak-proof performance of the sports water cup.

[0004] However, the above embodiment still has the following defects:

[0005] The above embodiment is difficult to control the quality during the injection molding process, resulting in the appearance of defective products that fail the inspection in the final product. It is also difficult to classify the defective products and analyze the causes, which makes it difficult to improve the process and handle subsequent defective products. Summary of the Invention

[0006] In view of the above problems, the present invention provides a two-color injection molding process for a sports water bottle, comprising the following steps:

[0007] Step 1: One-time injection molding, injecting the first color plastic into the first mold cavity, and after cooling to the crystallization temperature, obtaining the sports water bottle liner;

[0008] Step 2: One-time testing: remove the inner liner of the sports water bottle, test its internal and external temperature, hardness and surface integrity, and then sort and place qualified products and defective products;

[0009] Step 3: Secondary injection molding: transfer the qualified products to the second mold cavity and inject the second color plastic into the second mold cavity;

[0010] Step 4: Cooling molding: After the secondary injection molding is completed, the product is cooled to the demoulding temperature in stages to obtain the finished sports water cup;

[0011] Step 5: Secondary testing: Conduct secondary testing on the internal and external temperature, hardness and surface integrity of the finished sports water bottle.

[0012] Furthermore, the step 1 includes:

[0013] Pre-treating the first mold cavity, wherein the pre-treatment includes constant temperature heating and applying a release agent;

[0014] Heat the first color plastic to 220℃±20℃ and maintain.

[0015] Furthermore, the step 1 further includes:

[0016] Injecting the heated first color plastic into the first mold cavity in stages until the first mold cavity is filled;

[0017] The filled first color plastic is cooled until the temperature reaches the crystallization temperature of 115°C ± 5°C.

[0018] Furthermore, the step 2 includes:

[0019] Perform synchronous temperature detection on the inside and outside of the liner. The inner wall temperature standard of the liner is 115℃±3℃, the outer wall temperature standard is 110℃±3℃, and the temperature difference between the inside and outside is ≤5℃;

[0020] Several hardness testing points are selected at equal intervals on the inner wall of the liner, and the hardness standard of each testing point is 75±4HD.

[0021] Furthermore, the step 2 further includes:

[0022] Use visual inspection to simultaneously inspect the inner and outer walls of the liner for defects, including weld cracks, bubbles, and scratches;

[0023] The inner liners after inspection are classified and placed, among which Class A is qualified products, Class B is reworkable products, and Class C is scrapped products.

[0024] Furthermore, the step three includes:

[0025] Coat the inner wall of the second mold cavity with surfactant, and heat the cavity to a constant temperature of 45°C ± 5°C;

[0026] A six-axis manipulator is used to clamp the inner liner and transfer it to the second mold cavity. The clamping force standard of the manipulator is 10N±2N.

[0027] The position of the inner tank is calibrated by visual observation, and the positioning accuracy is controlled within 0.3mm.

[0028] Furthermore, the step three further includes:

[0029] Heat the second color plastic to 220℃±20℃, and then inject the second color plastic into the second mold cavity in stages;

[0030] The injection molding of the second color plastic includes four stages, and the injection pressure value of each stage decreases in a step-by-step manner.

[0031] Furthermore, the step three further includes:

[0032] When the second color plastic is injected, apply an interface compaction pressure of 10MPa±2MPa to the second mold cavity;

[0033] Maintain the mold temperature within the range of 90℃±5℃ for 2 minutes to form a gradual transition layer of 0.2mm±0.1mm.

[0034] Furthermore, the step 4 includes:

[0035] Cool the finished sports water bottle in three stages in sequence: mist cooling, water cooling and air cooling, until the surface temperature of the finished sports water bottle drops to 60℃±5℃;

[0036] Maintain the chamber temperature at 65°C ± 2°C for 5-8 minutes;

[0037] In-mold annealing was performed by applying a back pressure of 6 MPa ± 2 MPa.

[0038] A two-color injection molding process system for a sports water bottle, comprising:

[0039] The primary injection molding unit includes a first mold cavity and a first injection molding module; the first mold cavity is used for injection molding the inner liner, and the first mold cavity includes a temperature control module thereof; the first injection molding module includes a first storage module for loading and heating a first color plastic and a first injection module for injecting into the first mold cavity;

[0040] The inner liner detection unit includes a temperature detection unit, a hardness detection unit, and a defect detection unit. The temperature detection unit is used to detect the temperature of the inner and outer walls of the inner liner, the hardness detection unit is used to detect the hardness of the inner liner, and the defect detection unit is used to detect cracks, bubbles, and scratches on the surface of the inner liner.

[0041] The primary injection molding unit includes an inner liner transport calibration module and a second injection molding module; the inner liner transport calibration module includes transporting the inner liner to the second mold cavity and performing position calibration and fixation; the second injection molding module includes a second storage module for loading and heating the second color plastic and a second injection module for injecting into the second mold cavity.

[0042] The finished product inspection unit includes a finished product temperature inspection module for detecting the temperature of the finished sports water cup, a finished product hardness inspection module for detecting the hardness of the finished sports water cup, and a finished product visual inspection module for detecting surface defects of the finished sports water cup.

[0043] The beneficial effects of the present invention are:

[0044] After the liner is injected, the liner is first tested for internal and external temperature, hardness, and surface integrity to ensure that the liner that undergoes secondary injection molding is qualified, so as to reduce the hidden dangers of subsequent defective products. Then, after the finished product is completed, the internal and external temperature, hardness, and surface integrity are also tested a second time. In addition, a standard threshold is set for each inspection process, and the products are divided into Class A qualified products, Class B rework products, and Class C scrap products according to the threshold. Only Class A qualified products can enter the next inspection or molding process, ensuring the absolute quality of the finished product. The defective items and degree of defects of Class B and Class C can be carefully and accurately marked, providing available parameters for subsequent rework and subsequent process improvement. This not only ensures the quality of the existing finished sports water bottle, but also facilitates subsequent processing due to the accurate classification of non-qualified products, reduces the waste of raw materials, and also plays an auxiliary role in process improvement.

[0045] Both the primary and secondary injection molding processes utilize a multi-stage process, with the injection pressure and speed decreasing in steps at each stage. This improves the adaptability of the colored plastics to the mold cavity and addresses the impact of weld strength on the finished product during existing two- or multi-color injection molding. After the secondary injection molding process, interfacial compaction pressure is applied to the secondary mold cavity, and the temperature within the cavity is controlled using a staged temperature control method. This allows the surface temperature of the semi-finished sports water bottle to decrease in stages, creating a molecular-level entanglement in the transition layer between the two injection moldings. This improves adhesion between the two and reduces the likelihood of shedding.

[0046] First, the finished sports water bottle is subjected to a constant temperature treatment at 50-55°C for 35±5 minutes, and then subjected to several sets of thermal cycle treatments. This allows the finished sports water bottle to be loaded with high-temperature or low-temperature liquids in subsequent use without cracking or other damage, thereby improving the stability of the finished sports water bottle.

[0047] 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 pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1 A flow chart of a two-color injection molding process according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. 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 shall fall within the scope of protection of the present invention.

[0051] The embodiment of the present invention provides a two-color injection molding process for a sports water cup, for example, Figure 1 As shown, the following steps are included:

[0052] Step 1: One-time injection molding, injecting the first color plastic into the first mold cavity, and after cooling to the crystallization temperature, obtaining the sports water bottle liner;

[0053] Step 2: One-time testing: remove the inner liner of the sports water bottle, test its internal and external temperature, hardness and surface integrity, and then sort and place qualified products and defective products;

[0054] Step 3: Secondary injection molding: transfer the qualified products to the second mold cavity and inject the second color plastic into the second mold cavity;

[0055] Step 4: Cooling molding: After the secondary injection molding is completed, the product is cooled to the demoulding temperature in stages to obtain the finished sports water cup;

[0056] Step 5: Secondary testing: Conduct secondary testing on the internal and external temperature, hardness and surface integrity of the finished sports water bottle.

[0057] Exemplarily, the step 1 includes:

[0058] Pre-treating the first mold cavity, wherein the pre-treatment includes constant temperature heating and applying a release agent;

[0059] Specifically, first, the cavity temperature in the first mold cavity is heated to 60-65° C. and maintained at a constant temperature, and then a release agent is evenly coated on the inner wall of the first mold cavity to form a release layer, wherein the thickness of the release layer is 4±1 μm;

[0060] Preferably, the release agent is a nanocomposite water-based release agent, which includes:

[0061] Polydimethylsiloxane (PDMS) base material: 60-65wt%;

[0062] Silica nanoparticles: 5-8 wt%;

[0063] Fluorocarbon surfactant: 2-3wt%.

[0064] Heat the first color plastic to 220℃±20℃ and maintain;

[0065] Exemplarily, the step one further includes:

[0066] Injecting the heated first color plastic into the first mold cavity in stages until the first mold cavity is filled;

[0067] Specifically, the staged injection of the first color plastic includes three stages, wherein:

[0068] In the first stage, the injection pressure is 95MPa±5MPa, the injection speed is 55±5mm / s, and the volume of the first mold cavity is filled to 90%±3%;

[0069] In the second stage, the injection pressure is 65MPa±5MPa and the injection speed is 35±5mm / s to fill the remaining volume of the first mold cavity;

[0070] In the third stage, a holding pressure of 50 MPa ± 5 MPa is applied for 5 s ± 1 s.

[0071] Furthermore, in order to optimize the parameter values ​​during staged injection, it is first necessary to establish a flow analysis model based on software. Here, Moldflow software is preferably used. Then, the optimal parameter combination for crystallinity is determined by the response surface method. The mathematical formula of the response surface method is:

[0072] X C =0.35P+0.15V-0.08T+12.6

[0073] Among them, X C represents the crystallinity, its unit is %, P represents the holding pressure, its unit is MPa, V represents the injection speed, its unit is mm / s, and T represents the melt temperature, its unit is ℃.

[0074] Exemplarily, the step one further includes:

[0075] Cool the filled first color plastic until the temperature reaches the crystallization temperature of 115℃±5℃;

[0076] Specifically, the cooling process adopts a water-cooled heat exchange method, and the total cooling time is 15°C ± 3°C, which includes:

[0077] Pass cooling water at 15-20°C at a flow rate of 8±1 L / min for 3 seconds;

[0078] Stop cooling for 5 seconds and wait until the temperature inside and outside the liner is balanced;

[0079] Continue the above steps until the surface temperature of the inner tank reaches the crystallization temperature of 115℃±5℃.

[0080] Furthermore, after one injection molding is completed, the thickness of the liner is measured, and the tolerance between the thickness and the standard threshold is ±0.05mm.

[0081] Exemplarily, the step 2 includes:

[0082] Perform synchronous temperature detection on the inside and outside of the liner. The inner wall temperature standard of the liner is 115℃±3℃, the outer wall temperature standard is 110℃±3℃, and the temperature difference between the inside and outside is ≤5℃;

[0083] Preferably, the temperature detection adopts a non-contact infrared temperature measuring instrument to avoid heat exchange between the surface shell of the contact instrument and the inner tank, which leads to a decrease in temperature measurement accuracy.

[0084] Exemplarily, the step 2 further includes:

[0085] Select several hardness test points at equal intervals on the inner wall of the liner. The hardness standard of each test point is h0=75HD, and the standard deviation is ±4HD. The specific steps are as follows:

[0086] Select n test points in a circular array on the inner wall of the liner and measure the hardness value sequence:

[0087] {h1, h2, ...h x}

[0088] Then, the average hardness value of each measuring point is calculated based on the measured value of each hardness test point. The calculation formula of the average hardness value is:

[0089]

[0090] Among them, h actual Represents the average hardness value, its unit is HD, h i represents the measured hardness value of the i-th test point, and n represents the total number of test points.

[0091] After obtaining the average hardness value, the hardness standard deviation is calculated from the average hardness value. The calculation formula of the hardness standard deviation is:

[0092]

[0093] Among them, σ h Represents the standard deviation of hardness.

[0094] After the hardness standard deviation is calculated, it is compared with the standard threshold:

[0095] When the difference between the average hardness value of each measuring point and h0 is within 4HD, and σ h When ≤4HD, the liner is considered qualified;

[0096] When the difference between the average hardness value of one or more measuring points and h0 is greater than 4HD, but σ h When the HD is less than or equal to 4, the inner liner is considered to be reworkable.

[0097] When the difference between the average hardness value of one or more measuring points and h0 is greater than 4HD, and σ h When it is greater than or equal to 4HD, the liner is judged to be scrap.

[0098] Exemplarily, the step 2 further includes:

[0099] After the hardness test, qualified products are inspected for defects using visual inspection, including cracks, bubbles, and scratches.

[0100] Specifically, the visual inspection method uses a multispectral imaging device, and its measurement standards are visible light detection with a wavelength of 400-700nm, near-infrared detection with a wavelength of 900-1700nm, and ultraviolet-excited fluorescence detection with a wavelength of 360nm. Among them, visible light and near-infrared detection are used to detect cracks, bubbles and scratches, and ultraviolet-excited fluorescence detection is used to inspect release agent residues.

[0101] Furthermore, the crack detection includes visible weld marks with a length of ≤0.3mm, the bubble detection includes hollow protrusions on the inner and outer walls of the inner liner with a diameter of ≤0.5mm, and the scratch detection includes visible cracks with a depth of ≤0.2mm.

[0102] Furthermore, the standard value of the diameter of the release agent residue is ≤0.5 mm.

[0103] The inner tubes after testing are classified and placed, among which Class A is qualified products, Class B is reworkable products, and Class C is scrapped products;

[0104] Specifically, assuming that the crack detection value, bubble detection value, scratch detection value, and release agent residue detection value are X1, X2, X3, and X4 respectively,

[0105] When all values ​​are less than or equal to their maximum thresholds, they are considered Class A qualified products;

[0106] When one or both values ​​are greater than the maximum threshold, it is determined to be a Class B reworkable product;

[0107] When three or all of the values ​​are greater than their maximum thresholds, it is determined to be Class C scrap.

[0108] Exemplarily, the step three includes:

[0109] Coat the inner wall of the second mold cavity with surfactant, and heat the cavity to a constant temperature of 45°C ± 5°C;

[0110] Specifically, the thickness of the surfactant is 6±2 μm, and the surfactant includes the following components:

[0111] Maleic anhydride grafted polypropylene (PP-g-MAH): 60-65wt%

[0112] Nano-silicon dioxide: 3-5wt%

[0113] Silane coupling agent: 1-2wt%

[0114] Ethanol solvent: balance.

[0115] Exemplarily, the step three further includes:

[0116] A six-axis manipulator is used to clamp the inner liner and transfer it to the second mold cavity. The clamping force standard of the manipulator is 10N±2N.

[0117] The position of the inner tank is calibrated by visual observation, and the positioning accuracy is controlled within 0.3mm;

[0118] Specifically, after positioning is completed, a vacuum adsorption force of -0.8±0.2 MPa is applied to the inner container to fix the inner container.

[0119] Exemplarily, the step three further includes:

[0120] Heat the second color plastic to 220℃±20℃, and then inject the second color plastic into the second mold cavity in stages;

[0121] Specifically, the injection molding of the second color plastic includes four stages, and the injection pressure value of each stage decreases in a step-by-step manner:

[0122] The four stages are:

[0123] The first stage: injection pressure 80-85MPa, speed 40-50mm / s, filling 50% volume;

[0124] Second stage: switch to 65-70MPa, speed 60-70mm / s, filling to 85%;

[0125] The third stage: the pressure drops to 50-55 MPa, the speed reaches 30-40 mm / s, and the filling is completed;

[0126] Stage 4: Apply 35-40 MPa holding pressure for 5-7 seconds.

[0127] Furthermore, the parameters of the four-stage injection molding process are optimized, and the mathematical model formula for the parameter optimization is:

[0128] Q opt =0.25V 1.2 +0.15P 0.8 -0.08T 1.5 +5.3

[0129] Among them, Q opt represents the cross-sectional bonding mass, V represents the injection speed, its unit is mm / s; P represents the injection pressure, its unit is MPa; T represents the temperature of the second color plastic, its unit is ℃.

[0130] Exemplarily, the step three further includes:

[0131] When the second color plastic is injected, apply an interface compaction pressure of 10MPa±2MPa to the second mold cavity;

[0132] Maintain the mold temperature within the range of 90°C ± 5°C for 2 minutes to form a gradual transition layer of 0.2mm ± 0.1mm to obtain a semi-finished sports water cup;

[0133] Specifically, the formation of the gradient transition layer is achieved by the following temperature control:

[0134] 0-30s: The surface temperature of the semi-finished sports water bottle quickly drops from 190℃ to 150℃;

[0135] 30-90s: Maintain the surface temperature of the semi-finished sports water bottle at 150±5℃;

[0136] 90-120s: The surface temperature of the semi-finished sports water bottle is linearly cooled from 150°C to 120°C.

[0137] Specifically, after the secondary injection molding is completed, the peel strength of the joint of the two-layer structure of the semi-finished sports water bottle is tested, and the standard deviation value is greater than or equal to 30N / cm.

[0138] Exemplarily, the step 4 includes:

[0139] The finished sports water bottle is cooled in three stages in sequence: mist cooling, water cooling and air cooling, until the surface temperature of the finished sports water bottle drops to 60°C ± 5°C. The steps include:

[0140] High temperature section (120-100℃): adopt gas mist mixed cooling, cooling rate 8-10℃ / s, duration 15-20s;

[0141] Furthermore, the cooling gas is compressed air with a pressure of 0.4±0.1 MPa, and the cooling water mist is deionized water mist with a particle size of 30±5 um.

[0142] Medium temperature section (100-80℃): water cooling channel cooling is adopted, the cooling rate is 5-7℃ / s, and the duration is 25-30s;

[0143] Furthermore, the cooling water temperature is 15±2°C.

[0144] Low temperature section (80-50℃): adopt air cooling, slow cooling, cooling rate 2-3℃ / s, duration 40-45s;

[0145] Furthermore, during the air cooling operation, the wind speed is 7±2 m / s.

[0146] Exemplarily, the step 4 further includes:

[0147] Maintain the chamber temperature at 65°C ± 2°C for 5-8 minutes;

[0148] Apply a back pressure of 6MPa±2MPa for in-mold annealing to obtain a finished sports water cup. The calculation formula for controlling the in-mold annealing process parameters is:

[0149] t=0.15δ 2 +2.5

[0150] Where, t is the annealing time in min, and δ is the maximum wall thickness of the product in mm.

[0151] Through the above process, the residual stress during the secondary injection molding is eliminated by maintaining the constant temperature at 65℃±2℃ for 5-8 minutes and applying a back pressure of 6MPa±2MPa for in-mold annealing.

[0152] Exemplarily, the step 4 further includes:

[0153] The cooled finished sports water cup is ejected from the second mold cavity. Preferably, the ejection device is servo-electrically controlled, and the ejection speed includes three stages, which are:

[0154] Initial stage: 0.5-1mm / s, until the ejection displacement reaches 2mm;

[0155] Intermediate stage: 3-5mm / s, until the ejection displacement reaches 15mm;

[0156] Final stage: 1-2 mm / s until complete ejection.

[0157] Specifically, during the demoulding operation, the slope of the finished sports water cup is controlled within a range of ≤2°.

[0158] Furthermore, after demoulding is completed, the finished sports water bottle is subjected to a constant temperature treatment, wherein the constant temperature is in the range of 50-55°C and the constant temperature time is 35±5min;

[0159] Exemplarily, the step 4 further includes:

[0160] After the constant temperature is completed, the finished sports water bottle is subjected to a thermal cycle treatment, wherein the thermal cycle temperature is -5°C-60°C, the single time is 20±3 minutes, and the number of times is preferably 3 times.

[0161] First, the finished sports water bottle is subjected to a constant temperature treatment at 50-55°C for 35±5 minutes, and then subjected to several sets of thermal cycle treatments. This allows the finished sports water bottle to be loaded with high-temperature or low-temperature liquids in subsequent use without cracking or other damage, thereby improving the stability of the finished sports water bottle.

[0162] Exemplarily, the step five includes:

[0163] The internal and external temperatures of the finished sports water bottle are measured simultaneously. Several groups of measurement points are selected on the inner and outer walls respectively, and the average temperature measured at each measurement point on the inner and outer walls is calculated respectively. The average temperature of the inner wall of the finished sports water bottle is Y1, and the average temperature of the outer wall is Y2.

[0164] Specifically, when the temperature difference between Y1 and Y2 is ≤5°C, and the difference between the highest and lowest temperatures of the inner wall of the finished sports water bottle, as well as the difference between the highest and lowest temperatures of the inner wall, are both ≤3°C, the finished sports water bottle is judged to be a Class A qualified product;

[0165] When the temperature difference between Y1 and Y2 is greater than 5°C, or the difference between the highest and lowest temperatures on the inner wall of the finished sports water bottle is greater than 3°C, the finished sports water bottle is judged to be a Class B reworkable product;

[0166] When the temperature difference between Y1 and Y2 is greater than 5°C, or the difference between the highest and lowest temperatures of the inner wall of the finished sports water cup, and the difference between the highest and lowest temperatures of the inner wall are both greater than 3°C, the finished sports water cup is judged to be Class C scrap.

[0167] Exemplarily, the step five further includes:

[0168] After the temperature measurement, the hardness of the Class A finished sports water bottle is measured. The hardness measurement is to divide the finished sports water bottle into 5 layers with equal height spacing, where each layer is in a circular array and 4 measurement points are taken. The mathematical formula for the hardness measurement is:

[0169]

[0170] Among them, H grad represents the hardness gradient coefficient, h top,k Represents the average hardness of the measurement point closest to the cup mouth, its unit is HD, h bottom,k It represents the average hardness of the measurement point closest to the bottom of the cup. Its unit is HD, and k represents the serial number of the measurement point.

[0171] When H grad When the hardness is ≤3HD, the finished sports water bottle is judged to be a Class A qualified product;

[0172] When 3HD<H grad When the hardness is ≤5HD, the finished sports water bottle is judged to be Class B and can be reworked;

[0173] H grad When the hardness is greater than 5HD, the finished sports water bottle is judged to be a Class C scrap product.

[0174] Exemplarily, the step five further includes:

[0175] After hardness measurement, surface defect measurement is performed on the finished Class A sports water bottle. The measurement is performed using a visual inspection method. The measurement items are the total area of ​​cracks, the total area of ​​bubbles, and the total area of ​​scratches, which are all calculated using the following mathematical formulas:

[0176]

[0177] Among them, ρ d represents the total area of ​​cracks, bubbles or scratches; w represents the weight of the total area of ​​cracks, bubbles or scratches, and the weight of the total area of ​​cracks = 1.2, the weight of the total area of ​​bubbles = 1, and the weight of the total area of ​​scratches = 0.8.

[0178] Furthermore, assuming that the total area of ​​cracks is w1, the total area of ​​bubbles is w2, and the total area of ​​scratches is w3,

[0179] When the total area of ​​the three is ≤0.15%, the surface defect measurement of the finished sports water bottle is judged to be a Class A qualified product;

[0180] When the total area of ​​the three is greater than 0.15% and less than or equal to 0.3%, the surface defect measurement of the finished sports water bottle is determined to be a Class B reworkable product;

[0181] When the total area of ​​the three is greater than 0.3%, the surface defect measurement of the finished sports water bottle is determined to be Class C scrap.

[0182] The above embodiment has the following beneficial effects:

[0183] After the liner is injected, the liner is first tested for internal and external temperature, hardness, and surface integrity to ensure that the liner that undergoes secondary injection molding is qualified, so as to reduce the hidden dangers of subsequent defective products. Then, after the finished product is completed, the internal and external temperature, hardness, and surface integrity are also tested a second time. In addition, a standard threshold is set for each inspection process, and the products are divided into Class A qualified products, Class B rework products, and Class C scrap products according to the threshold. Only Class A qualified products can enter the next inspection or molding process, ensuring the absolute quality of the finished product. The defective items and degree of defects of Class B and Class C can be carefully and accurately marked, providing available parameters for subsequent rework and subsequent process improvement. This not only ensures the quality of the existing finished sports water bottle, but also facilitates subsequent processing due to the accurate classification of non-qualified products, reduces the waste of raw materials, and also plays an auxiliary role in process improvement.

[0184] Both the primary and secondary injection molding processes utilize a multi-stage process, with the injection pressure and speed decreasing in steps at each stage. This improves the adaptability of the colored plastics to the mold cavity and addresses the impact of weld strength on the finished product during existing two- or multi-color injection molding. After the secondary injection molding process, interfacial compaction pressure is applied to the secondary mold cavity, and the temperature within the cavity is controlled using a staged temperature control method. This allows the surface temperature of the semi-finished sports water bottle to decrease in stages, creating a molecular-level entanglement in the transition layer between the two injection moldings. This improves adhesion between the two and reduces the likelihood of shedding.

[0185] First, the finished sports water bottle is subjected to a constant temperature treatment at 50-55°C for 35±5 minutes, and then subjected to several sets of thermal cycle treatments. This allows the finished sports water bottle to be loaded with high-temperature or low-temperature liquids in subsequent use without cracking or other damage, thereby improving the stability of the finished sports water bottle.

[0186] In addition, based on the above-mentioned two-color injection molding process method for a sports water cup, an embodiment of the present invention further proposes a two-color injection molding process system for a sports water cup, comprising:

[0187] The primary injection molding unit includes a first mold cavity and a first injection molding module; the first mold cavity is used for injection molding the inner liner, and the first mold cavity includes a temperature control module thereof; the first injection molding module includes a first storage module for loading and heating a first color plastic and a first injection module for injecting into the first mold cavity;

[0188] The inner liner detection unit includes a temperature detection unit, a hardness detection unit, and a defect detection unit. The temperature detection unit is used to detect the temperature of the inner and outer walls of the inner liner, and is preferably a non-contact infrared temperature measuring device; the hardness detection unit is used to detect the hardness of the inner liner, and is preferably a Shore hardness tester; the defect detection unit is used to detect cracks, bubbles, and scratches on the surface of the inner liner, and is preferably a visual detection device;

[0189] The primary injection molding unit includes an inner liner transport calibration module and a second injection molding module; the inner liner transport calibration module includes transporting the inner liner to the second mold cavity and performing position calibration and fixation; the second injection molding module includes a second storage module for loading and heating the second color plastic and a second injection module for injecting into the second mold cavity.

[0190] The finished product inspection unit includes a finished product temperature inspection module for detecting the temperature of the finished sports water cup, a finished product hardness inspection module for detecting the hardness of the finished sports water cup, and a finished product visual inspection module for detecting surface defects of the finished sports water cup.

[0191] In addition, when the above modules are executed, they also include other steps for implementing the above two-color injection molding process method, which will not be described in detail here.

[0192] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A two-color injection molding process for a sports water bottle, characterized by: The following steps are involved: Step 1: One-time injection molding, injecting the first color plastic into the first mold cavity, and after cooling to the crystallization temperature, obtaining the sports water bottle liner; Step 2: One-time testing: remove the inner liner of the sports water bottle, test its internal and external temperature, hardness and surface integrity, and then sort and place qualified products and defective products; Step 3: Secondary injection molding: transfer the qualified products to the second mold cavity and inject the second color plastic into the second mold cavity; Step 4: Cooling molding: After the secondary injection molding is completed, the product is cooled to the demoulding temperature in stages to obtain the finished sports water cup; Step 5: Secondary testing: Conduct secondary testing on the internal and external temperature, hardness and surface integrity of the finished sports water bottle.

2. The two-color injection molding process for a sports water bottle according to claim 1, characterized in that: The step one comprises: Pre-treating the first mold cavity, wherein the pre-treatment includes constant temperature heating and applying a release agent; Heat the first color plastic to 220℃±20℃ and maintain.

3. The two-color injection molding process for a sports water bottle according to claim 2, characterized in that: The step one further comprises: Injecting the heated first color plastic into the first mold cavity in stages until the first mold cavity is filled; The filled first color plastic is cooled until the temperature reaches the crystallization temperature of 115°C ± 5°C.

4. The two-color injection molding process for a sports water bottle according to claim 3, characterized in that: The second step includes: Perform synchronous temperature detection on the inside and outside of the liner. The inner wall temperature standard of the liner is 115℃±3℃, the outer wall temperature standard is 110℃±3℃, and the temperature difference between the inside and outside is ≤5℃; Several hardness testing points are selected at equal intervals on the inner wall of the liner, and the hardness standard of each testing point is 75±4HD.

5. The two-color injection molding process for a sports water bottle according to claim 4, characterized in that: The second step also includes: Use visual inspection to simultaneously inspect the inner and outer walls of the liner for defects, including weld cracks, bubbles, and scratches; The inner liners after inspection are classified and placed, among which Class A is qualified products, Class B is reworkable products, and Class C is scrapped products.

6. The two-color injection molding process for a sports water bottle according to claim 5, characterized in that: The step three includes: Coat the inner wall of the second mold cavity with surfactant, and heat the cavity to a constant temperature of 45°C ± 5°C; A six-axis manipulator is used to clamp the inner liner and transfer it to the second mold cavity. The clamping force standard of the manipulator is 10N±2N. The position of the inner tank is calibrated by visual observation, and the positioning accuracy is controlled within 0.3mm.

7. The two-color injection molding process for a sports water bottle according to claim 6, characterized in that: The step three also includes: Heat the second color plastic to 220℃±20℃, and then inject the second color plastic into the second mold cavity in stages; The injection molding of the second color plastic includes four stages, and the injection pressure value of each stage decreases in a step-by-step manner.

8. The two-color injection molding process for a sports water bottle according to claim 7, characterized in that: The step three also includes: When the second color plastic is injected, apply an interface compaction pressure of 10MPa±2MPa to the second mold cavity; Maintain the mold temperature within the range of 90℃±5℃ for 2 minutes to form a gradual transition layer of 0.2mm±0.1mm.

9. The two-color injection molding process for a sports water bottle according to claim 8, characterized in that: The fourth step includes: Cool the finished sports water bottle in three stages in sequence: mist cooling, water cooling and air cooling, until the surface temperature of the finished sports water bottle drops to 60℃±5℃; Maintain the chamber temperature at 65°C ± 2°C for 5-8 minutes; In-mold annealing was performed by applying a back pressure of 6 MPa ± 2 MPa.

10. A two-color injection molding process system for a sports water bottle, characterized by: include: The primary injection molding unit includes a first mold cavity and a first injection molding module; the first mold cavity is used for injection molding the inner liner, and the first mold cavity includes a temperature control module thereof; the first injection molding module includes a first storage module for loading and heating a first color plastic and a first injection module for injecting into the first mold cavity; The inner liner detection unit includes a temperature detection unit, a hardness detection unit, and a defect detection unit. The temperature detection unit is used to detect the temperature of the inner and outer walls of the inner liner, the hardness detection unit is used to detect the hardness of the inner liner, and the defect detection unit is used to detect cracks, bubbles, and scratches on the surface of the inner liner. The primary injection molding unit includes an inner liner transport calibration module and a second injection molding module; the inner liner transport calibration module includes transporting the inner liner to the second mold cavity and performing position calibration and fixation; the second injection molding module includes a second storage module for loading and heating the second color plastic and a second injection module for injecting into the second mold cavity. The finished product inspection unit includes a finished product temperature inspection module for detecting the temperature of the finished sports water cup, a finished product hardness inspection module for detecting the hardness of the finished sports water cup, and a finished product visual inspection module for detecting surface defects of the finished sports water cup.

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