Valve body injection molding process and device

Abstract

The application belongs to the technical field of injection molding process, and particularly relates to a valve body injection molding process and device, which comprises compounding, injection molding, debinding and sintering, and a mold temperature control method for injection molding comprises the following steps: obtaining temperature difference values in each heat exchange channel, calculating average values and comparing, and identifying channels with large heat exchange efficiency difference; then, according to the number of abnormal channels, adjusting in stages, for a small number of abnormal channels, adjusting the heat exchange efficiency, when there are many abnormal channels, synchronously adjusting the power of the heat exchange medium supply device and the channel heat exchange efficiency, so as to efficiently eliminate the heat exchange efficiency difference between channels, ensure the uniformity of the heat exchange efficiency of each heat exchange channel of the mold, provide stable temperature conditions for valve body injection molding, and ensure the molding quality.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of injection molding process, and particularly relates to a valve body injection molding process and device. BACKGROUND

[0002] In the field of metal valve body manufacturing, as the performance and precision requirements of metal valve bodies are continuously improved with the development of industry, the traditional manufacturing process gradually fails to meet the needs, and the MIM (metal injection molding) technology is increasingly applied in the metal valve body injection molding process due to its advantages of being able to produce complex-shaped parts and having high precision and high efficiency; the MIM metal injection molding process mainly includes the steps of mixing of metal powder and binder, injection molding, and defatting and sintering.

[0003] In the process of metal valve body injection molding by using the MIM technology, temperature control is a key link; as the metal valve body cavity has irregularity, the heat exchange efficiency of the heat exchange channels to different parts of the cavity is different; this phenomenon has been confirmed by many related researches and actual production cases; for example, in the production of some metal valve bodies with complex structures, it is found by temperature monitoring equipment that the temperature change rate and the final temperature value of different parts of the cavity are obviously deviated at the same heating or cooling stage; this uneven heating problem will cause many adverse consequences, such as residual stress in the metal valve body, which further affects the mechanical properties and dimensional accuracy of the metal valve body, and reduces the product qualification rate; it can also cause defects such as shrinkage marks and deformation on the surface of the metal valve body, affecting the appearance quality and use performance. SUMMARY

[0004] The purpose of the present application is to solve the above-mentioned technical problems, and to provide a valve body injection molding process and device, which can self-adaptively adjust the heat exchange efficiency of the heat exchange channels in the mold to ensure uniform heat exchange of different parts of the cavity.

[0005] Therefore, the present application provides a valve body injection molding process, which comprises mixing, injection molding, defatting and sintering, and the temperature control method of the mold in the injection molding process comprises:

[0006] S1: based on the length of the heat exchange channel of the heat exchange medium flowing in the mold and the flow of the heat exchange medium, the required time T passing through the inlet and outlet of the heat exchange channel is calculated and determined;

[0007] S2: the temperature of the heat exchange medium at the inlet of the heat exchange channel and the temperature of the heat exchange medium at the outlet of the heat exchange channel after the interval T is obtained, the temperature difference is calculated and determined, and the average value of the temperature difference corresponding to the plurality of heat exchange channels in the mold is calculated;

[0008] S3: Obtain multiple sets of data difference values by comparing the average value with the temperature difference of each heat exchange channel, and screen out data difference values exceeding a preset data difference value range, and determine the corresponding heat exchange channel in the mold;

[0009] S4: Based on the number of heat exchange channels in S3 whose data difference values exceed the preset data difference value range:

[0010] ① When the number of heat exchange channels is equal to 0, repeat S1-S4:

[0011] ② When the number of heat exchange channels is less than or equal to 1 / 2 of the total number of heat exchange channels, adjust the heat exchange efficiency of the corresponding heat exchange channel, and repeat S1-S4 after the adjustment is completed;

[0012] ③ When the number of heat exchange channels is greater than 1 / 2 of the total number of heat exchange channels, respectively count the number of heat exchange channels with positive and negative data difference values, and according to the statistical result, select whether to adjust the power of the heat exchange medium supply device and the heat exchange efficiency of the heat exchange channel at the same time, and repeat S1-S4 after the adjustment is completed.

[0013] In the above technical solution, further in S4③:

[0014] When the number of data difference values that are positive or negative is greater than or equal to 4 / 5 of the total number, adjust the power of the heat exchange medium supply device to be reduced or increased, and at the same time, adjust the heat exchange efficiency of the corresponding heat exchange channel with the high proportion of data difference values and the original normal heat exchange channel affected by the power adjustment.

[0015] When the number of data difference values that are positive and negative is less than 4 / 5 of the total number, the heat exchange efficiency of the heat exchange medium of the corresponding heat exchange channel with positive or negative data difference values is reduced or increased.

[0016] In the above technical solution, further:

[0017] When the data difference value is positive, the heat exchange efficiency is adjusted to be reduced by adjusting the flow rate of the heat exchange medium of the corresponding heat exchange channel to be reduced or the temperature to be reduced or both the flow rate and the temperature to be reduced;

[0018] When the data difference value is negative, the heat exchange efficiency is adjusted to be increased by adjusting the flow rate of the heat exchange medium of the corresponding heat exchange channel to be increased or the temperature to be increased or both the flow rate and the temperature to be increased.

[0019] In the above technical solution, further in S4①, it also includes:

[0020] Acquire the ambient temperature of the environment where the current mold is located, judge and determine whether the ambient temperature is within the preset ambient temperature range, if yes, maintain the temperature control of S1-S4, if not, acquire the temperature control stage of the injection molding equipment, and according to the temperature control stage, adjust the power of the heat exchange medium supply device in advance, and repeat S1-S4 after the adjustment is completed.

[0021] The temperature control stage includes a heating stage or a cooling stage of the mold.

[0022] In the above technical solution, further:

[0023] If the mold is in the heating stage, and the ambient temperature is higher than the maximum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the lower limit of the preset power.

[0024] If the mold is in the heating stage, and the ambient temperature is lower than the minimum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the upper limit of the preset power.

[0025] In the above technical solution, further:

[0026] If the mold is in the cooling stage, and the ambient temperature is higher than the maximum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the upper limit of the preset power.

[0027] If the mold is in the cooling stage, and the ambient temperature is lower than the minimum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the lower limit of the preset power.

[0028] In the above technical solution, further:

[0029] In S2, the average value of the temperature difference of the plurality of heat exchange channels in the mold is calculated by removing one maximum value and one minimum value and then calculating the average value.

[0030] In the above technical solution, further:

[0031] In S1, the flow of the heat exchange medium is detected and calculated by detecting the flow at both ends of the heat exchange channel and calculating the average value.

[0032] In the above technical solution, further:

[0033] The flow average value of each heat exchange channel is compared, and the corresponding heat exchange channel with a flow value difference exceeding the preset flow deviation range is screened out, and the pressure at both ends of the heat exchange channel is detected.

[0034] The present application provides a valve body injection molding process device, comprising:

[0035] A mold is provided with a plurality of heat exchange channels, and flow meters and thermometers are arranged at both ends of the heat exchange channels.

[0036] A flow regulating valve is arranged at one end of the heat exchange channel inlet and used for regulating the flow in the corresponding heat exchange channel.

[0037] A heat exchange medium supply device is connected to the plurality of heat exchange channels and used for circulating the heat exchange medium in the plurality of heat exchange channels.

[0038] A sub-heat exchange medium supply device is arranged in the heat exchange channel and used for regulating the temperature of the corresponding heat exchange channel.

[0039] A control unit is connected to each device and used for receiving feedback from the flow meters, thermometers and pressure sensors and performing calculation and control in each step.

[0040] The heat exchange medium supply device and the sub-heat exchange medium supply device both include hot water supply mechanisms and cold water supply mechanisms.

[0041] The present application has the following advantages:

[0042] 1. The temperature difference in each heat exchange channel is obtained and averaged, and then compared with each heat exchange channel to obtain the corresponding heat exchange channel with a large difference in heat exchange efficiency, and then the heat exchange efficiency of the corresponding heat exchange channel is adjusted to eliminate the difference in heat exchange efficiency of each heat exchange channel, thereby ensuring the uniformity of the heat exchange efficiency of each heat exchange channel.

[0043] 2. The number of heat exchange channels with a large difference in heat exchange efficiency is detected and controlled in stages. When the number is small, the corresponding heat exchange channel is directly adjusted, and when the number is large, the overall heat exchange efficiency is adjusted, and the individual heat exchange channel and the normally normal heat exchange channel affected by the overall heat exchange efficiency adjustment are adjusted, thereby reducing the adjustment range of the corresponding heat exchange channel, improving the adjustment efficiency, and making the overall heat exchange efficiency of the heat exchange channel faster meet the preset data difference range and achieve uniformity.

[0044] 3. The power of the heat exchange medium supply device is adjusted in advance before the temperature difference exceeds the limit, combined with the temperature control stage (heating stage or cooling stage) of the workshop temperature and injection molding equipment, to prevent the temperature from rising or falling too fast and to avoid the lag response of the adjustment, improve the temperature control precision and efficiency, and increase the process robustness and the adaptability of the production environment. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a schematic diagram of the process flow of the present application;

[0046] Figure 2is a schematic diagram of the connection of the devices of the present application;

[0047] Figure 3 is a structural schematic diagram of the mold of the present application;

[0048] Figure 4 is a side view of the mold of the present application;

[0049] Figure 5 is a sectional view at A-A in the present application; Figure 4

[0050] Figure 6 is an enlarged view at B in the present application; Figure 5

[0051] Figure 7 is an enlarged view at C in the present application; Figure 5

[0052] The marks in the figure are indicated as: 1, mold; 2, heat exchange channel; 20, stepped hole; 3, flow meter; 4, thermometer; 5, flow regulating valve; 6, heat exchange medium supply device; 7, sub-heat exchange medium supply device; 70, inner tube; 71, connecting cylinder; 710, cavity; 711, through hole; 72, fixing disc; 73, first sealing gasket; 74, shell; 740, protrusion; 75, sleeve; 750, annular clamping groove; 751, annular protrusion; 76, second sealing gasket; 77, buckle; 78, pushing piece; 79, end cover; 80, elastic pad; 81, spring; 9, control unit. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present application.

[0054] Embodiment 1:

[0055] The present embodiment provides a valve body injection molding process, including mixing in an internal mixer, injection molding, debinding, and sintering, and the temperature control method of the mold in the injection molding process includes:

[0056] S1: based on the length of the heat exchange channel and the flow of the heat exchange medium in the mold, the required time T through the heat exchange channel inlet and outlet is calculated and determined;

[0057] S2: the temperature of the heat exchange medium at the inlet of the heat exchange channel and the temperature of the heat exchange medium at the outlet of the heat exchange channel after interval T time are obtained, the temperature difference is calculated and determined, and the average value of the temperature difference corresponding to the plurality of heat exchange channels in the mold is calculated; ​​​

[0058] S3: Obtain multiple sets of data difference values by comparing the average value with the temperature difference of each heat exchange channel, and screen out data difference values exceeding the preset data difference value range, and determine the corresponding heat exchange channel in the mold;

[0059] S4: Based on the number of heat exchange channels in S3 whose data difference values exceed the preset data difference value range:

[0060] ①: When the number of heat exchange channels is equal to 0, repeat S1-S4:

[0061] ②: When the number of heat exchange channels is less than or equal to 1 / 2 of the total number of heat exchange channels, adjust the heat exchange efficiency of the corresponding heat exchange channel, and repeat S1-S4 after the adjustment is completed;

[0062] ③: When the number of heat exchange channels is greater than 1 / 2 of the total number of heat exchange channels, respectively count the number of heat exchange channels with positive and negative data difference values, and according to the statistical result, select whether to adjust the power of the heat exchange medium supply device and the heat exchange efficiency of the heat exchange channel at the same time, and repeat S1-S4 after the adjustment is completed;

[0063] Wherein, the preset data difference value range is a key control factor affecting the uniformity of the overall heat exchange efficiency, for example, the smaller the preset data difference value, the higher the uniformity of the heat exchange efficiency, but the frequency of adjustment will also increase accordingly, on the contrary, the lower the uniformity of the heat exchange efficiency, but the frequency of adjustment will decrease accordingly, therefore, according to the process requirements, reasonable value can be taken to ensure that the uniformity meets the process requirements, and the frequency of adjustment is appropriately reduced, the present application is not limited, the skilled person in the art can determine according to the process requirements, which will not be repeated here;

[0064] At the same time, when calculating the time T, the distance length between the flow detection point and the heat exchange channel and the distance length from the flow detection point to the flow detection point of the heat exchange channel outlet flow meter need to be added.

[0065] As can be seen from the embodiment, based on obtaining the temperature difference in each heat exchange channel and calculating the average value, and then comparing each heat exchange channel with the average value, the corresponding heat exchange channel with large difference in heat exchange efficiency is obtained, and then the heat exchange efficiency of the corresponding heat exchange channel is adjusted to eliminate the difference in heat exchange efficiency of each heat exchange channel, thereby ensuring the uniformity of the heat exchange efficiency of each heat exchange channel;

[0066] And in ③ of S4, in the case that the number of heat exchange channels whose data difference exceeds the preset data difference range is large, when the number of positive data difference or negative data difference accounts for most, the power of the heat exchange medium supply device is adjusted first, and then the corresponding heat exchange channels or the original normal heat exchange channels affected are adjusted, which can reduce the adjustment range, and although the number of heat exchange channels that need to be adjusted increases in some cases, the overall adjustment efficiency is greater than adjusting only the corresponding heat exchange channels, effectively ensuring the response speed of temperature adjustment.

[0067] Embodiment 2:

[0068] The embodiment provides a valve body injection molding process, in addition to including the technical solutions of the above embodiments, further having the following technical features, in ③ of S4:

[0069] When the number of positive data difference or negative data difference is greater than or equal to 4 / 5 of the total number, the power of the heat exchange medium supply device is adjusted to be reduced or increased, and the heat exchange efficiency of the corresponding heat exchange channels and the original normal heat exchange channels affected by the power adjustment is adjusted in the opposite direction of the data difference and the high proportion.

[0070] When the number of positive data difference and the number of negative data difference are both less than 4 / 5 of the total number, the heat exchange efficiency of the heat exchange medium of the corresponding heat exchange channels with positive data difference or negative data difference is reduced or increased;

[0071] When the data difference is positive, the power of the heat exchange medium supply device is reduced and / or the heat exchange efficiency of the heat exchange channel is reduced, and when the data difference is negative, the power of the heat exchange medium supply device is increased and / or the heat exchange efficiency of the heat exchange channel is increased.

[0072] As can be seen from the embodiment, by detecting the number of heat exchange channels with large differences in heat exchange efficiency and performing step-by-step control, when the number is small, the corresponding heat exchange channels are directly adjusted locally, when the number is large, the overall heat exchange efficiency is adjusted first, and individual heat exchange channels and the original normal heat exchange channels affected by the overall heat exchange efficiency adjustment are adjusted, thereby reducing the adjustment range of the corresponding heat exchange channels, improving the adjustment efficiency, and making the overall heat exchange efficiency of the heat exchange channels faster meet the preset data difference range and achieve uniformity.

[0073] Embodiment 3:

[0074] The embodiment provides a valve body injection molding process, in addition to including the technical solutions of the above embodiments, further having the following technical features:

[0075] When the data difference value is positive, the heat exchange efficiency is adjusted to be reduced by adjusting the flow rate or temperature or both of the heat exchange medium of the corresponding heat exchange channel;

[0076] When the data difference value is negative, the heat exchange efficiency is adjusted to be increased by adjusting the flow rate or temperature or both of the heat exchange medium of the corresponding heat exchange channel;

[0077] Wherein, the flow rate of the heat exchange medium of the corresponding channel is adjusted and controlled by a flow rate adjusting valve, and the temperature of the heat exchange medium is adjusted by a sub-supply heat exchange medium device arranged in the corresponding heat exchange channel.

[0078] It can be seen from the embodiment that by adjusting the flow rate or temperature or both of the heat exchange medium of the corresponding heat exchange channel, the pertinence and speed of adjusting the heat exchange efficiency of the corresponding heat exchange channel can be improved, the uniformity of the heat exchange efficiency of different parts of the cavity can be ensured, and the control of product quality can be ensured.

[0079] Embodiment 4:

[0080] The embodiment provides a valve body injection molding process, in addition to the technical solutions of the above-mentioned embodiments, further having the following technical features, in ① of S4, further comprising:

[0081] Obtaining the ambient temperature of the environment where the current mold is located, judging and determining whether the ambient temperature is within the preset ambient temperature range, if yes, maintaining the temperature control of S1-S4, if no, obtaining the temperature control stage of the injection molding equipment, and adjusting the power of the supply heat exchange medium device in advance according to the temperature control stage, and repeating S1-S4 after the adjustment is completed;

[0082] Wherein, the temperature control stage includes a heating stage or a cooling stage of the mold;

[0083] At the same time, the preset ambient temperature range is the ambient temperature range when the mold is normally produced at room temperature (20-25℃), which is usually 3-5℃ higher than room temperature, which depends on the specific details of the ventilation in the production environment or the mold heat insulation plate, therefore the present application is not limited, and it is a conventional preset made by the production environment test of the skilled in the art, which will not be repeated here.

[0084] It can be seen from the embodiment that by adjusting the power of the supply heat exchange medium device in advance in combination with the workshop temperature and the temperature control stage (heating stage or cooling stage) of the injection molding equipment before the temperature difference value exceeds the limit, the preventive control is achieved, the lag response of the adjustment caused by the rapid heating or cooling is avoided, the temperature control precision and efficiency are improved, the process robustness is increased, and the adaptability of the production environment is improved.

[0085] Embodiment 5:

[0086] The embodiment provides a valve body injection molding process, in addition to comprising the technical scheme of the above embodiment, further has the following technical features:

[0087] If the mold is in the heating stage, and the ambient temperature is higher than the maximum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the preset lower limit of the power by reducing the power of the heat exchange medium supply device;

[0088] If the mold is in the heating stage, and the ambient temperature is lower than the minimum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the preset upper limit of the power by increasing the power of the heat exchange medium supply device.

[0089] The preset power is a power safety boundary value (including the upper limit and the lower limit) of the heat exchange medium supply device, which is pre-set based on the mold thermal characteristics, heat exchange medium parameters and process requirements, and is known to those skilled in the art, and will not be repeated here.

[0090] It can be seen from the embodiment that, by knowing that the mold is in the heating stage, and according to the ambient temperature, the power of the heat exchange medium supply device is adjusted to the preset lower limit and upper limit of the power, the mold can be prevented from being affected by the environment, and the situation of too fast or too slow heating during the heating process can be avoided, such as keeping the preset minimum power of the heat exchange medium supply device when the ambient temperature is higher than the maximum value of the preset ambient temperature range, reducing the heating efficiency, and avoiding the situation of too fast heating, and vice versa, which can avoid the situation of too slow heating, ensure the preventive control, avoid the situation of too fast or too slow heating response hysteresis caused by the ambient temperature, improve the temperature control precision and efficiency, and increase the process robustness and the adaptability of the production environment.

[0091] Embodiment 6:

[0092] The embodiment provides a valve body injection molding process, in addition to comprising the technical scheme of the above embodiment, further has the following technical features:

[0093] If the mold is in the heating stage, and the ambient temperature is higher than the maximum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the preset lower limit of the power by reducing the power of the heat exchange medium supply device;

[0094] If the mold is in the heating stage, and the ambient temperature is lower than the minimum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to the preset upper limit of the power by increasing the power of the heat exchange medium supply device.

[0095] It can be seen from the embodiment that, corresponding to the heating stage, when the mold is in the cooling stage, the power of the heat exchange medium device is adjusted to the preset lower limit and upper limit of the power according to the ambient temperature, which can avoid the mold from being affected by the environment and cause the cooling to be too fast or too slow. For example, when the ambient temperature is higher than the maximum value of the preset ambient temperature range, the maximum preset power of the heat exchange medium device is maintained to improve the cooling efficiency and avoid the situation of slow cooling. Conversely, it can also avoid the situation of fast cooling, ensure preventive control, avoid the situation of slow or fast cooling caused by the response lag of the ambient temperature, improve the temperature control accuracy and efficiency, and increase the process robustness and the adaptability of the production environment.

[0096] Embodiment 7:

[0097] The embodiment provides a valve body injection molding process, in addition to the technical solutions of the above-mentioned embodiments, further having the following technical features:

[0098] In S2, the average value of the temperature difference corresponding to the plurality of heat exchange channels in the mold is calculated by removing one maximum value and one minimum value and then calculating the average value.

[0099] It can be seen from the embodiment that, by removing one maximum value and one minimum value and then calculating the average value, the accuracy of obtaining the average value can be improved, and the influence of individual data difference on the accuracy of obtaining the average value can be avoided, such as the temperature difference caused by the blockage or blockage of the heat exchange channel.

[0100] However, it should be noted that when the average value is obtained, one maximum value and one minimum value are removed, but when the data difference is calculated, the temperature difference corresponding to all heat exchange channels is uniformly averaged.

[0101] Embodiment 8:

[0102] The embodiment provides a valve body injection molding process, in addition to the technical solutions of the above-mentioned embodiments, further having the following technical features:

[0103] In S1, the detection and calculation of the flow of the heat exchange medium is: detecting the flow at both ends of the heat exchange channel and calculating the average value.

[0104] It can be seen from the embodiment that, by averaging the flow, the accuracy of flow monitoring can be improved.

[0105] Embodiment 9:

[0106] The embodiment provides a valve body injection molding process, in addition to the technical solutions of the above-mentioned embodiments, further having the following technical features:

[0107] The flow average value of each heat exchange channel is compared, and the corresponding heat exchange channel with a flow value difference exceeding a preset flow deviation range is screened out, and the pressure at both ends of the heat exchange channel is detected.

[0108] The preset flow deviation range is a preset flow deviation range obtained by artificially blocking the heat exchange channel and testing according to the allowable blocking degree to the complete blocking degree, which can be obtained by testing by a person skilled in the art, and is not described here due to the size difference of the heat exchange channels of each mold.

[0109] As can be seen from the embodiment, by comparing each flow average value, the corresponding heat exchange channel with a flow value difference exceeding a preset flow deviation range is screened out, and the flow adjustment record is called, such as recent flow adjustment of the corresponding heat exchange channel, it is judged that the corresponding heat exchange channel may exist in the blocking condition, and the pressure at both ends of the corresponding heat exchange channel is called;

[0110] When the flow difference exceeds the preset flow deviation range, and the pressure at both ends of the corresponding heat exchange channel exists deviation, it is judged that there is a large degree of blocking, and the corresponding heat exchange channel is marked on the display screen, and the machine is stopped and an alarm is given, which can effectively ensure the product yield and prolong the service life of the mold.

[0111] Embodiment 10

[0112] The embodiment provides a valve body injection molding process, in addition to the technical solutions of the above-mentioned embodiments, further having the following technical features, comprising the following steps:

[0113] T1: The stainless steel powder is first dried in vacuum at 100-150℃ for 2-4h, sieved through 200 meshes, and a small amount of phthalate plasticizer is added to the polyformaldehyde binder; nitrogen gas is introduced into the internal mixer to maintain a micro-positive pressure of 5-10kPa, and the powder and the binder are uniformly mixed by adopting 50rpm pre-mixing for 10min→150rpm strong mixing for 30min→80rpm homogenization for 20min in stages; the cavity temperature is controlled to be ≤80℃ by circulating water.

[0114] T2: The injection molding equipment barrel is gradiently heated (160℃→190℃→220℃), the mold temperature is controlled to be 60-80℃, and the injection pressure is adjusted in stages (filling 100-150MPa, pressure maintaining 80-100MPa, cooling 50MPa); after the material is injected into the mold, it stays for 5-10min, and then the temperature is lowered to room temperature at a rate of 1-2℃ / min, and then demolding is performed; the size precision (tolerance ±0.1%) and apparent defects of the valve body green body are detected immediately after demolding.

[0115] T3: The valve body green body is first immersed in acetone for 2-4h for pre-debinding, and then placed in a debinding furnace; heated to 300℃ at a rate of 1℃ / min, then fogging oxalic acid is introduced (fogging pressure 0.3-0.5MPa) in the 300℃-650℃ section, while nitrogen gas is injected at a flow rate of 5-10L / min to purge the exhaust gas, and the oxygen content in the furnace is controlled to be <100ppm to avoid powder oxidation.

[0116] T4: The valve body green body is placed in a sintering furnace, and the sintering furnace is first vacuumed to <10-3Pa, heated to 1000℃ at a rate of 5℃ / min to remove volatile matter, then heated to the sintering temperature corresponding to the steel grade (e.g. 1350-1400℃ for 316L) for 1-2h, during which the protection gas is switched to Ar:N2=8:2; after holding, the furnace is cooled to 500℃, then circulating water is introduced for rapid cooling to room temperature, and multiple point thermocouples are arranged in the furnace to ensure that the temperature difference is ≤±5℃.

[0117] T5: After sintering, the green body density (≥95% of the theoretical density), hardness and microstructure (grain size ≤20μm) are detected, and the debinding exhaust gas is treated by oxalic acid condensation recovery, activated carbon adsorption + catalytic combustion, the raw materials are preheated using the sintering furnace waste heat to reduce energy consumption by 15%-20%, and finally the qualified valve body green body is obtained.

[0118] As can be seen from the embodiment, by powder drying and screening, binder modification and segmented mixing under nitrogen protection, the feed dispersibility is improved and the valve body green body layering bubbles are reduced; gradient temperature control and mold slow cooling demolding with segmented pressure injection cooperate to control the valve body green body size tolerance within ±0.1%, reduce the risk of internal stress and cracking; pre-debinding combined with catalytic segmented treatment reduces the binder residue and reduces the deformation rate of the valve body green body, and the inert atmosphere prevents powder oxidation; vacuum-atmosphere switching and precise temperature control process improve the green body density, refine the grain size, improve the tensile strength and elongation, and reduce the oxidation and decarburization defects; full-process detection closed-loop control improves the yield, waste gas treatment and waste heat recovery reduce energy consumption and environmental protection cost, and realizes the improvement of product performance, quality stability and production economy.

[0119] Example 11:

[0120] The embodiment provides a valve body injection molding process device, which comprises:

[0121] A mold 1 is provided with a plurality of heat exchange channels 2 from top to bottom, and flow meters 3, thermometers 4 and pressure sensors are arranged at both ends of the plurality of heat exchange channels 2, respectively.

[0122] A flow regulating valve 5 is installed at one end of the inlet of the heat exchange channel 2, and is used to regulate the flow in the corresponding heat exchange channel 2.

[0123] The supply heat exchange medium device 6 is connected to the plurality of heat exchange channels 2 and is used to circulate the heat exchange medium in the plurality of heat exchange channels 2;

[0124] The sub-supply heat exchange medium device 76 is installed in the heat exchange channel 2 and is used to adjust the temperature of the corresponding heat exchange channel 2;

[0125] The control unit 9 is connected to each device and is used to receive the feedback of the flow meter 3, the temperature meter 4, and the pressure sensor and the calculation and control in each step;

[0126] The supply heat exchange medium device 6 and the sub-supply heat exchange medium device 76 each include a hot water supply mechanism and a cold water supply mechanism;

[0127] Meanwhile, the specific structure and model of the flow meter 3, the temperature meter 4, the pressure sensor, the flow regulating valve 5, the supply heat exchange medium device 6, and the control unit 9 and the specific installation position are all prior art, and a person skilled in the art can select and apply them from conventional devices, and thus will not be described here;

[0128] In addition, the hot water supply mechanism and the cold water supply mechanism can be connected to the same heat exchange channel 2 or different heat exchange channels 2, which is based on the specific mold 1 design and system configuration and is a conventional selection, and thus will not be described here.

[0129] As can be seen from the embodiment, by providing the sub-supply heat exchange medium device 76 and installing it in each heat exchange channel 2, the temperature of the heat exchange medium in each heat exchange channel 2 can be adjusted and controlled, and the heat exchange efficiency of the heat exchange medium in each heat exchange channel 2 can be adjusted.

[0130] Embodiment 12:

[0131] The embodiment provides a valve body injection molding process device, in addition to the technical solutions of the above-mentioned embodiments, further has the following technical features, the sub-supply heat exchange medium device 76 includes:

[0132] The inner tube 70 is coaxially installed in the heat exchange channel 2;

[0133] The connecting barrel 71 is installed at both ends of the mold 1 located at the heat exchange channel 2, an inner cavity 710 is formed in communication with the heat exchange channel 2, and a through hole 711 is formed on the inner wall of the cavity 710;

[0134] The fixed disc 72 is installed at one end of the inner tube 70 and abuts against the connecting barrel 71 at one end, and is provided with a first sealing gasket 73;

[0135] The shell 74 is fixedly connected to the connecting barrel 71 at the other end;

[0136] The sleeve 75 is fixedly sleeved on the inner tube 70, and a plurality of annular clamping grooves 750 are formed on the surface of the sleeve 75, and an annular protrusion 751 is formed at one end of the sleeve 75, and the second sealing gasket 76 is arranged between the annular protrusion 751 and the shell 74;

[0137] The buckle 77 is installed in the shell 74, and is matched with the plurality of annular clamping grooves 750, and can be close to or away from the axis of the sleeve 75 on the radial surface;

[0138] The pusher 78 is sleeved on the inner tube 70, and is used to push the reciprocating movement of the buckle 77;

[0139] The end cover 79 is installed on the side of the shell 74 away from the connecting cylinder 71, and is used to limit one end of the pusher 78 and the buckle 77 in the shell 74;

[0140] The elastic pad 80 is installed on the side of the buckle 77 away from the axis;

[0141] The spring 81 is sleeved on the inner tube 70, and is located between the sleeve 75 and the pusher 78;

[0142] The heat exchange medium in the heat exchange channel 2 flows from bottom to top, and the heat exchange medium in the inner tube 70 flows from top to bottom, and the inner tube 70 is not connected with the heat exchange channel 2 and the cavity 710, and the buckle 77 is circumferentially arranged, and the protruding part 740 for limiting the radial rotation of the buckle 77 is arranged on the inner wall of the shell 74;

[0143] And the heat exchange channel 2 can be vertically arranged on the mold 1, and the heat exchange channel 2 is arranged with a stepped hole 20 at the joint, so that the inner wall of the heat exchange channel 2 is flush with the inner wall of the connecting cylinder 71, and the connecting cylinder 71 and the heat exchange channel 2 are connected by screw thread or interference fit;

[0144] At the same time, the diameter of the annular protrusion 751 is the same as or slightly smaller than the diameter of the heat exchange channel 2, and the interference fit or welding can be used between the sleeve 75 and the inner tube 70 and between the shell 74 and the connecting cylinder 71.

[0145] As can be seen from the embodiment, by arranging the inner tube 70 in the heat exchange channel 2 and connecting by the joint, the temperature of the heat exchange medium in the heat exchange channel 2 can be increased or decreased by passing the corresponding heat exchange medium into the inner tube 70, so as to adjust and control the heat exchange efficiency of the single heat exchange channel 2;

[0146] The through hole 711 of the inner wall of the chamber 710 is convenient for the heat exchange medium in the heat exchange channel 2 to be distinguished from the heat exchange medium in the inner tube 70, and the heat exchange medium in the heat exchange channel 2 flows from bottom to top, so that the flow in the heat exchange channel 2 always flows in a full state under the influence of gravity, thereby improving the stability of the heat exchange efficiency, and the heat exchange medium in the inner tube 70 flows from top to bottom, so that the heat exchange efficiency between the heat exchange medium in the inner tube 70 and the heat exchange medium in the heat exchange channel 2 can be ensured.

[0147] One end of the inner tube 70 is fixed by the fixing disc 72, and the other end of the inner tube 70 is fixed by the sleeve 75 and the buckle 77, so as to improve the installation stability of the inner tube 70 in the heat exchange channel 2, facilitate the installation and disassembly of the inner tube 70, and facilitate the maintenance and replacement of the inner tube 70. Meanwhile, the first sealing gasket 73 and the second sealing gasket 76 can ensure the sealing performance of the two ends of the inner tube 70, so as to avoid leakage of the heat exchange medium in the heat exchange channel 2.

[0148] The arrangement of the pushing member 78, the elastic pad 80 and the spring 81 can further improve the convenience of installation and disassembly of the inner tube 70. Specifically, when the inner tube 70 needs to be disassembled, the pushing member 78 is only needed to be pressed, the axial movement of the pushing member 78 is realized, the buckle 77 is separated from the annular clamping groove 750, and the elastic pad 80 is compressed. The spring 81 can facilitate the resetting of the pushing member 78, and can also facilitate the axial falling of the inner tube 70 from the heat exchange channel 2.

[0149] The plurality of annular clamping grooves 750 can facilitate the adjustment of the compression degree between the first sealing gasket 73 and the second sealing gasket 76. When the sealing performance of the first sealing gasket 73 and the second sealing gasket 76 is weakened, the compression degree of the first sealing gasket 73 and the second sealing gasket 76 can be increased by pressing the fixing disc 72, so as to prolong the effective service life of the sealing, provide a certain buffer period for replacement, avoid leakage during production, and ensure the production efficiency.

[0150] The size of the annular protrusion 751 on the sleeve 75 is the same as or slightly smaller than the diameter of the annular protrusion 751 and the diameter of the heat exchange channel 2. When the inner tube 70 is installed in the heat exchange channel 2, the annular protrusion 751 is in sliding connection with the inner wall of the heat exchange channel 2, so that the inner tube 70 can be kept coaxial with the heat exchange channel 2 during axial movement, thereby improving the stability and convenience of installation of the inner tube 70. The side of the annular protrusion 751 away from the axis can be arranged in an arc shape according to the need, so as to reduce the frictional resistance between the inner tube 70 and the inner wall of the heat exchange channel 2 during installation.

[0151] The embodiments of the present application are described above with reference to the drawings, and the embodiments and features in the embodiments of the present application can be combined with each other without conflict, and the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection of the present application.

Claims

1. A valve body injection molding process, including mixing, injection molding, degreasing and sintering, characterized in that: The temperature control method of the mold in the injection molding process comprises: S1: Based on the length of the heat exchange channel and the flow rate of the heat exchange medium in the mold, calculate and determine the time T required for the heat exchange medium to pass through the inlet and outlet ends of the heat exchange channel; S2: Obtain the temperature of the heat exchange medium at the inlet of the heat exchange channel and the temperature of the heat exchange medium at the outlet of the heat exchange channel after an interval of T, calculate and determine the temperature difference, and calculate the average value of the temperature differences corresponding to multiple heat exchange channels in the mold; S3: Comparing the average value with the temperature difference of each heat exchange channel to obtain multiple sets of data differences, screening out data differences exceeding a preset data difference range, and determining the corresponding heat exchange channels in the mold; S4: The number of heat exchange channels whose data difference in S3 exceeds the preset data difference range: ①: When the number of heat exchange channels is equal to 0, repeat S1-S4: ②: When the number of heat exchange channels is less than or equal to 1 / 2 of the total number of heat exchange channels, adjust the heat exchange efficiency of the corresponding heat exchange channels. After the adjustment is completed, repeat S1-S4; ③: When the number of heat exchange channels is greater than 1 / 2 of the total number of heat exchange channels, the number of heat exchange channels with positive and negative statistical differences is counted respectively, and according to the statistical results, it is determined whether to adjust the power of the heat exchange medium supply device and the heat exchange efficiency of the heat exchange channels at the same time. After the adjustment is completed, repeat S1-S4; Among them, in S4 ③: When the number of positive or negative data differences is greater than or equal to 4 / 5 of the total number, the power of the heat exchange medium supply device is adjusted to decrease or increase, and the heat exchange efficiency of the corresponding heat exchange channel with the opposite data difference ratio and the original normal heat exchange channel affected by the power adjustment is adjusted at the same time; When the number of both positive and negative data differences is less than 4 / 5 of the total number, the heat exchange efficiency of the heat exchange medium in the corresponding heat exchange channel with the positive or negative data difference is reduced or increased.

2. The valve body injection molding process according to claim 1, characterized in that: When the data difference is a positive number, the heat exchange efficiency is adjusted to decrease by adjusting the flow rate or temperature of the heat exchange medium in the corresponding heat exchange channel, or by adjusting both the flow rate and temperature simultaneously; When the data difference is a negative number, the heat exchange efficiency is adjusted to increase by adjusting the flow rate or temperature of the heat exchange medium in the corresponding heat exchange channel, or by adjusting both the flow rate and temperature.

3. The valve body injection molding process according to claim 1, characterized in that: In S4, ①, it also includes: Obtain the ambient temperature of the current mold environment, determine whether the ambient temperature is within the preset ambient temperature range, and if so, maintain the temperature control of S1-S4. If not, obtain the temperature control stage of the injection molding equipment and adjust the power of the heat exchange medium supply device in advance according to the temperature control stage. After the adjustment is completed, repeat S1-S4. The temperature control stage includes the mold being in a heating stage or a cooling stage.

4. The valve body injection molding process according to claim 3, characterized in that: If the mold is in the heating stage and the ambient temperature is higher than the maximum value of the preset ambient temperature range, the power of the heat exchange medium supply device is reduced to the preset power lower limit by adjusting; If the mold is in the heating stage and the ambient temperature is lower than the minimum value of the preset ambient temperature range, the power of the heat exchange medium supply device is increased to the preset power upper limit by adjusting the power.

5. The valve body injection molding process according to claim 3, characterized in that: If the mold is in the cooling stage and the ambient temperature is higher than the maximum value of the preset ambient temperature range, the power of the heat exchange medium supply device is increased to the preset power upper limit by adjusting the power; If the mold is in the cooling stage and the ambient temperature is lower than the minimum value of the preset ambient temperature range, the power of the heat exchange medium supply device is adjusted to be reduced to the preset power lower limit.

6. The valve body injection molding process according to claim 1, characterized in that: In S2, the average value of the temperature differences corresponding to the multiple heat exchange channels in the mold is calculated by removing a maximum value and a minimum value and then calculating the average value.

7. The valve body injection molding process according to claim 1, characterized in that: In S1 , the flow rate of the heat exchange medium is detected and calculated by detecting the flow rates at both ends of the heat exchange channel and calculating the average value.

8. The valve body injection molding process according to claim 7, characterized in that: The average flow rate of each heat exchange channel is compared to screen out the corresponding heat exchange channels whose flow rate value difference exceeds the preset flow rate deviation range, and the pressure at both ends of the heat exchange channel is detected at the same time.

9. A device suitable for the valve body injection molding process according to any one of claims 1 to 8, characterized in that: include: The mold (1) is provided with a plurality of heat exchange channels (2) extending from top to bottom, and flow meters (3), thermometers (4) and pressure sensors are respectively provided at both ends of the plurality of heat exchange channels (2); A flow regulating valve (5) is installed at one end of the inlet of the heat exchange channel (2) and is used to regulate the flow in the corresponding heat exchange channel (2); A heat exchange medium supply device (6) is connected to the plurality of heat exchange channels (2) and is used to circulate the heat exchange medium through the plurality of heat exchange channels (2); A heat exchange medium supply device (7) is installed in the heat exchange channel (2) and is used to adjust the temperature of the corresponding heat exchange channel (2); a control unit (9), connected to each device and used to receive feedback from the flow meter (3), the temperature meter (4) and the pressure sensor, and to perform calculations and controls in each step; Wherein, the heat exchange medium supply device (6) and the sub-heat exchange medium supply device (7) both include a hot water supply mechanism and a cold water supply mechanism.

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