Valve body injection molding process and device

Abstract

The invention belongs to the technical field of injection molding processes, and particularly relates to a valve body injection molding process and device.The valve body injection molding process comprises internal mixing, injection molding, degreasing and sintering, and a mold temperature control method for injection molding comprises the steps that the channel with the large heat exchange efficiency difference is recognized by obtaining the temperature difference value in all heat exchange channels, calculating the average value and conducting comparison; performing staged adjustment according to the number of the abnormal channels, and specifically adjusting the heat exchange efficiency for a small number of abnormal channels; when the number of abnormal channels is large, the power of the heat exchange medium supplying device and the channel heat exchange efficiency are synchronously adjusted, so that the heat exchange efficiency difference between the channels is efficiently eliminated, it is guaranteed that the heat exchange efficiency of the heat exchange channels of the mold is uniform, stable temperature conditions are provided for valve body injection molding, and the molding quality is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of injection molding technology, and in particular relates to a valve body injection molding process and device. Background Art

[0002] In the field of metal valve body manufacturing, with the continuous improvement of industrial development requirements for metal valve body performance and precision, traditional manufacturing processes are gradually unable to meet the demand. MIM (metal injection molding) technology is increasingly used in metal valve body injection molding processes because of its ability to produce complex-shaped parts with high precision and high efficiency. The MIM metal injection molding process mainly includes the steps of mixing metal powder and binder, injection molding, degreasing and sintering.

[0003] In the process of metal valve body injection molding using MIM technology, temperature control is a key link; due to the irregularity of the metal valve body cavity, the heat exchange efficiency of the heat exchange channel to each part of the cavity is different; this phenomenon has been confirmed by many related studies and actual production cases; for example, in the production of some complex structure metal valve bodies, it was found through temperature monitoring equipment that there was a significant deviation in the temperature change rate and final temperature value of different parts of the cavity during the same heating or cooling stage; this uneven heating problem can lead to many adverse consequences, such as residual stress inside the metal valve body, which in turn affects the mechanical properties and dimensional accuracy of the metal valve body and reduces the product qualification rate; it may also cause defects such as shrinkage marks and deformation on the surface of the metal valve body, affecting the appearance quality and performance. Summary of the invention

[0004] The purpose of the present invention is to provide a valve body injection molding process and device to solve the above-mentioned technical problems, so as to achieve the effect of adaptively adjusting the heat exchange efficiency of each heat exchange channel in the mold to ensure uniform heat exchange in different parts of the cavity.

[0005] In view of this, the present invention provides a valve body injection molding process, including mixing, injection molding, degreasing and sintering, and the temperature control method of the mold in the injection molding includes:

[0006] S1: Based on the length of the heat exchange channel through which the heat exchange medium flows in the mold and the flow rate of the heat exchange medium, calculate and determine the time T required to pass through both ends of the heat exchange channel;

[0007] S2: obtaining 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 time, calculating and determining the temperature difference, and calculating the average value of the temperature differences corresponding to multiple heat exchange channels in the mold;

[0008] S3: by comparing the average value with the temperature difference of each heat exchange channel, a plurality of groups of data differences are obtained, and the data differences exceeding the preset data difference range are screened out, and the corresponding heat exchange channels are determined in the mold;

[0009] S4: The number of heat exchange channels whose data difference in S3 exceeds the preset data difference 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, the number of heat exchange channels with positive and negative statistical differences is counted respectively, and according to the statistical results, it is selected 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. After the adjustment is completed, repeat S1-S4.

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

[0014] 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 at the same time, the heat exchange efficiency of the corresponding heat exchange channel whose data difference is opposite to the high proportion and the original normal heat exchange channel affected by the power adjustment is adjusted.

[0015] When the number of positive and negative data differences 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 the positive or negative data difference is reduced or increased.

[0016] In the above technical solution, further:

[0017] 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 the flow rate and temperature simultaneously;

[0018] 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 the flow rate and temperature at the same time.

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

[0020] Obtain the ambient temperature of the current mold environment, 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, 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, and repeat S1-S4 after the adjustment is completed;

[0021] The temperature control stage includes when the mold is in a heating up stage or a cooling down stage.

[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 reduced to the preset power lower limit by adjusting;

[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 increased to the preset power upper limit by adjusting.

[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 increased to the preset power upper limit by adjusting;

[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 be reduced to the preset power lower limit.

[0028] In the above technical solution, further:

[0029] In S2, the average value of the temperature difference 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.

[0030] In the above technical solution, further:

[0031] In S1, the flow rate of the heat exchange medium is detected and calculated in the following manner: the flow rates at both ends of the inlet and outlet of the heat exchange channel are detected, and the average value is calculated.

[0032] In the above technical solution, further:

[0033] The average flow rate of each heat exchange channel is compared to select the corresponding heat exchange channels whose flow value difference exceeds the preset flow deviation range, and the pressure at both ends of the heat exchange channel is detected at the same time.

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

[0035] The mold has a plurality of heat exchange channels extending from top to bottom, and flow meters and thermometers are respectively arranged at both ends of the plurality of heat exchange channels;

[0036] A flow control valve is installed at one end of the heat exchange channel inlet and is used to adjust the flow in the corresponding heat exchange channel;

[0037] A heat exchange medium supply device is connected to a plurality of heat exchange channels and is used to circulate the heat exchange medium in the plurality of heat exchange channels;

[0038] A heat exchange medium supply device is installed in the heat exchange channel and is used to adjust the temperature of the corresponding heat exchange channel;

[0039] A control unit connected to each device and used to receive feedback from the flow meter, the temperature meter and the pressure sensor and to perform calculations and controls in each step;

[0040] Wherein, the heat exchange medium supply device and the sub-heat exchange medium supply device both include a hot water supply mechanism and a cold water supply mechanism.

[0041] The beneficial effects of the present invention are:

[0042] 1. 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 channels with large differences in heat exchange efficiency are 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.

[0043] 2. 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 locally adjusted. When the number is large, the overall heat exchange efficiency is adjusted first. At the same time, for individual heat exchange channels and the original normal heat exchange channels affected by the overall heat exchange efficiency adjustment, the adjustment range of the corresponding heat exchange channels is reduced, the adjustment efficiency is improved, and the heat exchange efficiency of all heat exchange channels is more quickly in line with the preset data difference range and achieves uniformity.

[0044] 3. By adjusting the power of the heat exchange medium supply 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 exceeds the limit, preventive control can be achieved to avoid the delayed response of the adjustment caused by too fast heating or cooling, improve the temperature control accuracy and efficiency, increase the process robustness, and improve the adaptability of the production environment. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0046] Figure 2It is a schematic diagram of the connection of various devices of the present invention;

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

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

[0049] Figure 5 The present invention Figure 4 Sectional view at AA in the middle;

[0050] Figure 6 The present invention Figure 5 The enlarged view of point B in the middle;

[0051] Figure 7 The present invention Figure 5 Enlarged view of point C in the middle;

[0052] The markings in the figure are as follows: 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 tube; 710. chamber; 711. through hole; 72. fixed disk; 73. first sealing gasket; 74. shell; 740. protrusion; 75. sleeve; 750. annular groove; 751. annular protrusion; 76. second sealing gasket; 77. buckle; 78. pusher; 79. end cover; 80. elastic pad; 81. spring; 9. control unit. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions 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. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0054] Embodiment 1:

[0055] This embodiment provides a valve body injection molding process, including mixing, injection molding, degreasing and sintering. The temperature control method of the mold in the injection molding includes:

[0056] S1: Based on the length of the heat exchange channel through which the heat exchange medium flows in the mold and the flow rate of the heat exchange medium, calculate and determine the time T required to pass through both ends of the heat exchange channel;

[0057] S2: obtaining 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 time, calculating and determining the temperature difference, and calculating the average value of the temperature differences corresponding to multiple heat exchange channels in the mold;

[0058] S3: by comparing the average value with the temperature difference of each heat exchange channel, a plurality of groups of data differences are obtained, and the data differences exceeding the preset data difference range are screened out, and the corresponding heat exchange channels are determined in the mold;

[0059] S4: The number of heat exchange channels whose data difference in S3 exceeds the preset data difference 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, the number of heat exchange channels with positive and negative statistical differences is counted respectively, and according to the statistical results, it is selected 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. After the adjustment is completed, repeat S1-S4;

[0063] Among them, the preset data difference range is a key control factor affecting the uniformity of the overall heat exchange efficiency. For example, the smaller the preset data difference is, the higher the uniformity of the heat exchange efficiency is, but the frequency of adjustment will also increase accordingly. On the contrary, the lower the uniformity of the heat exchange efficiency is, the lower the frequency of adjustment will be. Therefore, a reasonable value can be taken according to the process requirements to ensure that the frequency of adjustment is appropriately reduced under the premise of ensuring the uniformity that meets the process requirements. This application does not limit it, and the technicians in the relevant technical field can determine it according to the process requirements, and it will not be repeated here.

[0064] At the same time, when calculating the time T, it is necessary to combine the distance between the flow detection point of the flow meter and the heat exchange channel and the distance between the flow detection point of the heat exchange channel outflow flow meter.

[0065] It can be seen from this embodiment that, 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 a 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 S4③, when the number of heat exchange channels whose data differences exceed the preset data difference range is large, when the data differences are mostly positive or negative, the adjustment amplitude can be reduced by first adjusting the power of the heat exchange medium supply device and then adjusting the corresponding heat exchange channel or the affected original normal heat exchange channel. Although in some cases the number of heat exchange channels that need to be adjusted will increase, due to the reduction of most of the adjustment amplitudes, the overall adjustment efficiency is greater than that of only adjusting the corresponding heat exchange channel, which effectively ensures the response speed of temperature regulation.

[0067] Embodiment 2:

[0068] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features, in S4 ③:

[0069] 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 at the same time, the heat exchange efficiency of the corresponding heat exchange channel whose data difference is opposite to the high proportion and the original normal heat exchange channel affected by the power adjustment is adjusted.

[0070] When the number of positive and negative data differences 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 the positive or negative data difference is reduced or increased;

[0071] Specifically, when the data difference is a positive number, the power of the heat exchange medium supply device is adjusted to decrease and / or the heat exchange efficiency of the heat exchange channel is adjusted to decrease; when the data difference is a negative number, the power of the heat exchange medium supply device is adjusted to increase and / or the heat exchange efficiency of the heat exchange channel is adjusted to increase.

[0072] It can be seen from the present embodiment that 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 locally adjusted, and when the number is large, the overall heat exchange efficiency is first adjusted, and at the same time, individual heat exchange channels and original normal heat exchange channels affected by the overall heat exchange efficiency adjustment are adjusted, thereby reducing the adjustment amplitude of the corresponding heat exchange channels and improving the adjustment efficiency, so that the heat exchange efficiency of all heat exchange channels can more quickly meet the preset data difference range and achieve uniformity.

[0073] Embodiment 3:

[0074] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0075] 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 the flow rate and temperature simultaneously;

[0076] When the data difference is a negative number, the heat exchange efficiency is increased by adjusting the flow rate or temperature of the heat exchange medium in the corresponding heat exchange channel, or by adjusting the flow rate and temperature at the same time;

[0077] The flow rate of the heat exchange medium in the corresponding channel is regulated and controlled by a flow regulating valve, and the temperature of the heat exchange medium is regulated by a sub-heat exchange medium supply device provided in the corresponding heat exchange channel.

[0078] It can be seen from this embodiment that by adjusting the flow rate or temperature of the heat exchange medium of the corresponding heat exchange channel or adjusting the flow rate and temperature at the same time, the targetedness and quickness of adjusting the heat exchange efficiency of the corresponding heat exchange channel can be improved, which is convenient for ensuring the uniformity of the heat exchange efficiency of different parts of the cavity and ensuring the control of product quality.

[0079] Embodiment 4:

[0080] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features, and in S4 (1), also includes:

[0081] Obtain the ambient temperature of the current mold environment, 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, 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, and repeat S1-S4 after the adjustment is completed;

[0082] Among them, the temperature control stage includes the mold being in the heating stage or cooling stage;

[0083] At the same time, the preset ambient temperature range is the ambient temperature range in which the mold is located when it is in normal production at room temperature (20-25°C), which is usually 3-5°C higher than the normal temperature. This depends on the ventilation in the production environment or the specific details of the mold insulation board. Therefore, this application does not limit it. It is a routine preset made by the relevant technical personnel based on the production environment test and will not be repeated here.

[0084] It can be seen from this embodiment that by adjusting the power of the heat exchange medium supply 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 exceeds the limit, preventive control is achieved to avoid a delayed response of the adjustment due to excessive heating or cooling, improve the temperature control accuracy and efficiency, increase the process robustness, and improve the adaptability of the production environment.

[0085] Embodiment 5:

[0086] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also 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 reduced to the preset power lower limit by adjusting;

[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 increased to the preset power upper limit by adjusting;

[0089] Among them, the preset power is the power safety boundary value (including upper and lower limits) of the heat exchange medium supply device which is pre-set based on the thermal characteristics of the mold, the heat exchange medium parameters and the process requirements. It is the prior art and is known to the technicians in the relevant technical field, so it will not be repeated here.

[0090] It can be seen from the present embodiment that by knowing that the mold is in the heating stage and adjusting the power of the heat exchange medium supply device to the preset power lower and upper limits according to the ambient temperature, the mold can be prevented from being affected by environmental factors and from heating up too quickly or too slowly during the heating process. For example, when the ambient temperature is higher than the maximum value of the preset ambient temperature range, the preset minimum power of the heat exchange medium supply device is maintained to reduce the heating efficiency and avoid heating up too quickly. Vice versa, heating up too slowly can be avoided, thereby ensuring preventive control and avoiding delays in response to heating up too quickly or too slowly due to ambient temperature. This improves the temperature control accuracy and efficiency, increases the process robustness, and improves the adaptability of the production environment.

[0091] Embodiment 6:

[0092] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0093] 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;

[0094] 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.

[0095] It can be seen from the present embodiment that, in the heating stage, correspondingly, when the mold is in the cooling stage, the power of the heat exchange medium supply device is adjusted to the preset power lower limit and upper limit according to the ambient temperature, so as to avoid the mold being affected by environmental factors and the occurrence of too fast or too slow cooling during the cooling process. For example, when the ambient temperature is higher than the maximum value of the preset ambient temperature range, the preset maximum power of the heat exchange medium supply device is maintained to improve the cooling efficiency and avoid the occurrence of too slow cooling. Vice versa, it can avoid the occurrence of too fast cooling, ensure preventive control, avoid the situation where the ambient temperature causes a response lag when the cooling is too slow or too fast, improve the temperature control accuracy and efficiency, increase the process robustness, and improve the adaptability of the production environment.

[0096] Embodiment 7:

[0097] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0098] In S2, the average value of the temperature difference 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.

[0099] It can be seen from this embodiment that by removing a maximum value and a minimum value and then calculating the average value, the accuracy of obtaining the average value can be improved, and the accuracy of obtaining the average value can be avoided to be affected by the large difference in individual data, such as the large or small temperature difference caused by the blockage or clogging of the heat exchange channel;

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

[0101] Embodiment 8:

[0102] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0103] In S1, the flow rate of the heat exchange medium is detected and calculated in the following manner: the flow rates at both ends of the heat exchange channel inlet and outlet are detected, and the average value is calculated;

[0104] It can be seen from this embodiment that detecting the flow rate by using the average value can improve the accuracy of flow rate monitoring.

[0105] Embodiment 9:

[0106] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0107] The average flow rate of each heat exchange channel is compared to select the corresponding heat exchange channels whose flow value difference exceeds the preset flow deviation range, and the pressure at both ends of the heat exchange channel is detected at the same time.

[0108] Among them, the preset flow deviation range is the preset flow deviation range obtained by artificially blocking the heat exchange channel and testing from the allowable blockage degree to the complete blockage degree. It can be obtained by technical personnel in the relevant technical field through experiments. Due to the differences in the sizes of heat exchange channels of each mold, it will not be repeated here.

[0109] It can be seen from this embodiment that by comparing each flow average value, the corresponding heat exchange channel whose flow value difference exceeds the preset flow deviation range is screened out, and the flow adjustment record is retrieved. If the flow adjustment of the corresponding heat exchange channel has not been performed recently, it is judged that the corresponding heat exchange channel may be blocked, and the pressure at both ends of the corresponding heat exchange channel is retrieved;

[0110] When the flow difference exceeds the preset flow deviation range and there is a deviation in the pressure at both ends of the corresponding heat exchange channel, it is judged that there is a large degree of blockage, and the corresponding heat exchange channel is marked on the display screen. At the same time, the machine is shut down and an alarm is issued, which can effectively ensure the product yield and extend the service life of the mold.

[0111] Example 10

[0112] This embodiment provides a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features, including the following steps:

[0113] T1: The stainless steel powder is first vacuum dried at 100-150℃ for 2-4h and sieved with 200 mesh. A small amount of phthalate plasticizer is added to the polyoxymethylene binder. Nitrogen is introduced into the internal mixer to maintain a slight positive pressure of 5-10kPa. The premixing is performed at 50rpm for 10min, the strong mixing is performed at 150rpm for 30min, and the homogenization is performed at 80rpm for 20min. The cavity temperature is controlled to be ≤80℃ by circulating water to ensure uniform mixing of the powder and the binder.

[0114] T2: The barrel of the injection molding equipment is gradually heated up (160℃→190℃→220℃), the mold temperature is controlled at 60-80℃, and the injection pressure is adjusted in stages (filling 100-150MPa, holding pressure 80-100MPa, cooling 50MPa); after the material is injected into the mold, it stays for 5-10min, and is cooled to room temperature at a rate of 1-2℃ / min before demolding. After demolding, the valve body green body dimensional accuracy (tolerance ±0.1%) and apparent defects are immediately inspected.

[0115] T3: Before catalytic degreasing, soak the valve body green body in acetone for 2-4 hours for pre-degreasing, and then place it in a degreasing furnace; heat it to 300℃ at a rate of 1℃ / min, then introduce atomized oxalic acid (atomization pressure 0.3-0.5MPa) in the 300℃-650℃ range, and at the same time inject nitrogen at a flow rate of 5-10L / min to purge the exhaust gas. The oxygen content in the furnace is controlled to be less than 100ppm to avoid powder oxidation.

[0116] T4: The valve body green body is placed in a sintering furnace, and the sintering furnace is first evacuated to <10-3Pa, and the temperature is raised to 1000℃ at 5℃ / min to remove volatiles, and then the temperature is raised to the corresponding steel grade sintering temperature (such as 1350-1400℃ for 316L) and kept warm for 1-2h, during which time it is switched to Ar:N 2 =8:2 protective gas; after heat preservation, cool to 500℃ with the furnace, and then introduce circulating water to quickly cool to room temperature. Multi-point thermocouples are configured in the furnace to ensure that the temperature difference is ≤±5℃.

[0117] T5: After sintering, the green density (≥95% of theoretical density), hardness and metallographic structure (grain size ≤20μm) are tested. At the same time, the degreasing waste gas is recovered by oxalic acid condensation, activated carbon adsorption + catalytic combustion treatment, and the raw materials are preheated with the waste heat of the sintering furnace to reduce energy consumption by 15%-20%, and finally a qualified valve body green body is obtained.

[0118] It can be seen from the present embodiment that the dispersion of feed is improved and the stratification bubbles of valve body green body are reduced through powder drying and screening, binder modification and segmented mixing and nitrogen protection; gradient temperature control and segmented pressure injection molding are combined with slow cooling and demolding of the mold to control the size tolerance of the valve body green body within ±0.1%, thereby reducing internal stress and cracking risks; pre-degreasing is combined with catalytic segmented treatment to reduce binder residue and reduce the deformation rate of the valve body green body, and the inert atmosphere prevents powder oxidation; vacuum-atmosphere switching and precise temperature control process can improve the green body density, refine the grains, improve the tensile strength and elongation, and reduce oxidation and decarburization defects; full-process detection and closed-loop control can improve the yield rate, and waste gas treatment and waste heat recovery can reduce energy consumption and environmental protection costs, thereby achieving improvements in product performance, quality stability and production economy.

[0119] Embodiment 11:

[0120] This embodiment provides a device for a valve body injection molding process, comprising:

[0121] The 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 respectively provided at both ends of the plurality of heat exchange channels 2;

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

[0123] 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 in the plurality of heat exchange channels 2;

[0124] The heat exchange medium supply 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] A control unit 9, connected to each device and used to receive feedback from the flow meter 3, the thermometer 4 and the pressure sensor and to perform calculations and controls in each step;

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

[0127] Meanwhile, the specific structures and models of the flow meter 3, the thermometer 4, the pressure sensor, the flow regulating valve 5, the heat exchange medium supply device 6 and the control unit 9 and the specific installation positions are all prior art, and are selected and applied by technicians in the relevant technical field from various traditional devices, and will not be described in detail here;

[0128] Furthermore, the hot water supply mechanism and the cold water supply mechanism can be connected to the same heat exchange channel 2 or to different heat exchange channels 2. This depends on the specific mold 1 design and system configuration and is an existing conventional choice, which will not be elaborated here.

[0129] It can be seen from the present embodiment that by setting up the sub-supply heat exchange medium device 76 and installing it in each heat exchange channel 2, it is convenient to adjust and control the heat exchange medium temperature of each heat exchange channel 2, so as to adapt to the above-mentioned control method for adjusting the heat exchange efficiency of the heat exchange medium in a single heat exchange channel 2.

[0130] Embodiment 12:

[0131] This embodiment provides a device for a valve body injection molding process, which, in addition to the technical solutions of the above embodiments, also has the following technical features: the heat exchange medium supply device 76 includes:

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

[0133] The connecting cylinder 71 is installed at both ends of the mold 1 at the heat exchange channel 2, and a cavity 710 communicating with the heat exchange channel 2 is formed inside, and a through hole 711 is opened on the inner wall of the cavity 710;

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

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

[0136] The sleeve 75 is fixedly sleeved on the inner tube 70 and has a plurality of annular grooves 750 on its surface. One end of the sleeve 75 extends to form an annular protrusion 751 and a second sealing gasket 76 is disposed between the sleeve and the housing 74.

[0137] The buckle 77 is installed in the housing 74 and is adapted to the plurality of annular grooves 750, and can move closer to or farther from the axis of the sleeve 75 in the radial plane;

[0138] A pusher 78 is sleeved on the inner tube 70 and is used to push the buckle 77 to reciprocate;

[0139] The end cover 79 is installed on the side of the housing 74 away from the connecting tube 71 and is used to restrict one end of the pusher 78 and the buckle 77 in the housing 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, while the heat exchange medium in the inner tube 70 flows from top to bottom, and the inner tube 70 is not connected to the heat exchange channel 2 and the chamber 710, and a plurality of buckles 77 are arranged around the circumference, and a protrusion 740 for limiting the radial rotation of the buckle 77 is provided on the inner wall of the shell 74;

[0143] Furthermore, the heat exchange channel 2 can be vertically opened on the mold 1, and a stepped hole 20 is opened at the joint of the heat exchange channel 2, so that the inner wall of the heat exchange channel 2 is flush with the inner wall of the connecting tube 71, and the connecting tube 71 and the heat exchange channel 2 are connected by threads 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 interference fit or welding can be used between the sleeve 75 and the inner tube 70 , and between the shell 74 and the connecting tube 71 .

[0145] It can be seen from this embodiment that by arranging the inner tube 70 in the heat exchange channel 2 and installing and connecting it through a 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, which is convenient for adjusting and controlling the heat exchange efficiency in a single heat exchange channel 2;

[0146] The through hole 711 formed on the inner wall of the chamber 710 facilitates the passage of the heat exchange medium in the heat exchange channel 2, which is separated from the heat exchange medium in the inner tube 70, and allows the heat exchange medium in the heat exchange channel 2 to flow from bottom to top, so that the flow in the heat exchange channel 2 always flows in a full state due to the influence of gravity, thereby improving the stability of the heat exchange efficiency. The heat exchange medium in the inner tube 70 flows from top to bottom, and through relative flow, the heat exchange efficiency between 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 plate 72, and then 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, and facilitate the installation and disassembly of the inner tube 70, thereby facilitating the maintenance and replacement of the inner tube 70. At the same time, the first sealing gasket 73 and the second sealing gasket 76 can ensure the sealing of both ends of the inner tube 70, and prevent the heat exchange medium in the heat exchange channel 2 from leaking;

[0148] The arrangement of the pusher 78, the elastic pad 80 and the spring 81 can further improve the convenience of installation and removal of the inner tube 70. Specifically, when the inner tube 70 needs to be removed, it is only necessary to press the pusher 78. The axial movement of the pusher 78 can cause the buckle 77 to separate from the annular groove 750 and compress the elastic pad 80. The spring 81 can facilitate the reset of the pusher 78 and promote the axial fall of the inner tube 70 from the heat exchange channel 2.

[0149] Furthermore, the plurality of annular grooves 750 can facilitate adjustment of the degree of compression between the first gasket 73 and the second gasket 76. When the sealing performance of the first gasket 73 and the second gasket 76 is weakened, the compression degree of the first gasket 73 and the second gasket 76 can be enhanced by pressing the fixing plate 72, thereby extending the effective life of the seal and providing a certain buffer period for replacement, thereby avoiding leakage during production and requiring immediate shutdown for maintenance, thereby ensuring 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 heat exchange channel 2, so that when the inner tube 70 is installed in the heat exchange channel 2, it can be slidably connected with the inner wall of the heat exchange channel 2, so that the inner tube 70 can remain nearly coaxial with the heat exchange channel 2 when moving axially, which can improve the stability and convenience of the installation of the inner tube 70, and the side of the annular protrusion 751 away from the axis can be set to an arc shape as needed, so as to reduce the friction resistance between the inner tube 70 and the inner wall of the heat exchange channel 2 when the inner tube 70 is installed.

[0151] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within 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 through which the heat exchange medium flows in the mold and the flow rate of the heat exchange medium, calculate and determine the time T required to pass through both ends of the heat exchange channel; S2: obtaining 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 time, calculating and determining the temperature difference, and calculating the average value of the temperature differences corresponding to multiple heat exchange channels in the mold; S3: by comparing the average value with the temperature difference of each heat exchange channel, a plurality of groups of data differences are obtained, and the data differences exceeding the preset data difference range are screened out, and the corresponding heat exchange channels are determined 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 channel, and repeat S1-S4 after the adjustment is completed; 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 selected 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. After the adjustment is completed, repeat S1-S4.

2. The valve body injection molding process according to claim 1, characterized in that: 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 whose data difference is opposite to the high proportion and the original normal heat exchange channel affected by the power adjustment is adjusted at the same time; When the number of positive and negative data differences 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 the positive or negative data difference is reduced or increased.

3. The valve body injection molding process according to claim 2, 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 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 the flow rate and temperature at the same time.

4. The valve body injection molding process according to claim 1, characterized in that: In S4①, it also includes: Obtain the ambient temperature of the current mold environment, 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, 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, and repeat S1-S4 after the adjustment is completed; The temperature control stage includes the mold being in a heating-up stage or a cooling-down stage.

5. The valve body injection molding process according to claim 4, 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.

6. The valve body injection molding process according to claim 4, 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; 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.

7. The valve body injection molding process according to claim 1, characterized in that: In S2, the average value of the temperature difference 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.

8. 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 in the following manner: the flow rates at both ends of the inlet and outlet of the heat exchange channel are detected, and the average value is calculated.

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

10. A device suitable for the valve body injection molding process according to any one of claims 1 to 9, characterized in that: include: The mold (1) is provided with a plurality of heat exchange channels (2) running through it from top to bottom, and flow meters (3), thermometers (4) and pressure sensors are respectively arranged 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 in 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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