Sol charging barrel for injection molding machine and manufacturing process

Abstract

The invention relates to a sol charging barrel for an injection molding machine and a manufacturing process. The sol charging barrel comprises the following raw materials in percentage by mass: 55-65% of nickel; 25%-35% of chromium; 1.8%-2.5% of vanadium; 0.5% to 1.8% of molybdenum; the balance is a binder and inevitably mixed impurities; a carbon steel core rod is also arranged in the inner cavity of the sol charging barrel and is used for enhancing the bending strength of the sol charging barrel; a seamless steel pipe cavity matched with the length of the sol charging barrel is selected, a carbon steel core rod is placed at the axis of the cavity, the mixed powder in the mass ratio is injected into the cavity, the cavity is compacted and then placed into a hot isostatic pressing furnace in a sealed mode, hot isostatic pressing process treatment is conducted in a vacuumizing environment, and a finished sol charging barrel product is obtained after a material body is machined. Through the combination of the material composition and the manufacturing process, the invention aims to provide excellent wear resistance and corrosion resistance, the excellent proportion of nickel and chromium endows the sol charging barrel with excellent corrosion resistance, and the addition of vanadium and molybdenum enhances the wear resistance of the sol charging barrel, so that the sol charging barrel has excellent performance in a humid or corrosive environment.

Description

Technical Field

[0001] This application relates to the technical field of sol cartridges, and particularly to a sol cartridge for an injection molding machine and its manufacturing process. Background Art

[0002] The sol cartridge for an injection molding machine, also known as a barrel, is a key component for melting plastics in an injection molding machine and forms a plasticizing component together with a screw. Its structural types are diverse, including integral barrels, composite barrels, bimetallic barrels, IKV barrels, etc. The manufacturing materials generally include 45# steel, 40Cr, 38CrMoAl, etc., and also use cast steel, ductile iron, high-quality cast iron, and novel materials such as Xaloy alloy. During operation, plastics are conveyed by a screw and are heated and softened into a melt under the combined action of barrel heating, screw frictional heat, and shear heat. The melt pressure pushes the screw backward. It mainly realizes the heating and plasticizing of plastics, material conveying, as well as mixing and shearing through external resistance heating in cooperation with screw rotation.

[0003] Most traditional sol cartridges for injection molding machines adopt the method of centrifugal casting alloy. The centrifugally cast barrels will have the problems of uneven HRC hardness and iron ion back-seepage.

[0004] Regarding the uneven HRC hardness, due to the difference in cooling rate, the cooling speeds of different parts of the barrel are different, resulting in different crystal grains and organizational structures; alloy composition segregation, and uneven distribution of some alloy elements under centrifugal force; unstable process parameters, such as fluctuations in rotational speed, casting temperature, and mold temperature. These factors comprehensively lead to uneven hardness. And the iron ion back-seepage is because there are defects such as pores and cracks inside the alloy, which become the migration channels for iron ions; the plastic raw materials contain corrosive components, or the corrosive medium generated in a high-temperature and humid environment destroys the alloy passivation film; and the formation of a potential difference when contacting other metal components promotes the migration and seepage of iron ions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to provide a sol cartridge for an injection molding machine and its manufacturing process, which solves the technical problems of uneven HRC hardness and iron ion back-seepage that occur when the traditional sol cartridge for an injection molding machine adopts the method of centrifugal casting alloy.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A sol cartridge for an injection molding machine, the sol cartridge comprises raw materials with the following mass fractions:

[0008] Nickel: 55% - 65%;

[0009] Chromium: 25% - 35%;

[0010] Vanadium: 1.8% - 2.5%;

[0011] Molybdenum: 0.5% - 1.8%;

[0012] The balance is binder and unavoidably mixed impurities;

[0013] A carbon steel mandrel is further arranged in the inner cavity of the melt cylinder, and the carbon steel mandrel is used to enhance the bending strength of the melt cylinder;

[0014] Select a seamless steel pipe cavity matching the length of the melt cylinder, place the carbon steel mandrel at the axis of the cavity, inject the mixed powder according to the above mass ratio into the cavity, seal it after compaction and put it into a hot isostatic pressing furnace, and perform hot isostatic pressing process treatment in a vacuum environment. After processing, the finished melt cylinder is obtained.

[0015] Furthermore, the particle size requirements of each metal powder are as follows: nickel: 70 - 140 μm, chromium: 70 - 140 μm, vanadium: 20 - 50 μm, molybdenum: 15 - 30 μm, and other impurities are not more than 140 μm.

[0016] Furthermore, the purity requirements of each metal powder are as follows: nickel > 99.9%, chromium 99.5%, vanadium > 99.65%, molybdenum > 99.9%.

[0017] The manufacturing process of a melt cylinder for an injection molding machine as described in any one of the above, includes the following steps:

[0018] Step 1: Weighing, configuring powders according to the mass fraction required for the melt cylinder, and mixing evenly;

[0019] Step 2: Prepare a seamless steel pipe with one end sealed, place the carbon steel mandrel at the axis of the cavity, and pour the mixed alloy powder into the cavity of the seamless steel pipe and compact it;

[0020] Step 3: Weld and seal the blank of the poured alloy powder and evacuate it;

[0021] Step 4: Place the sealed seamless steel pipe into a hot isostatic pressing furnace, gradually raise the temperature to 900 - 1000 °C, raise the pressure to 180 - 220 MPa, and maintain for not less than 5 hours;

[0022] Step 5: Cool down and reduce the pressure, cool with the furnace to room temperature, and take out the alloy bar stock;

[0023] Step 6: Grind the alloy bar stock to make a melt cylinder and conduct quality inspection

[0024] Furthermore, the ratio of the outer diameter of the carbon steel mandrel to the outer diameter of the alloy bar is 1:4.

[0025] Furthermore, a lower cover is sealed and welded to the lower port of the seamless steel pipe, and a positioning seat for positioning and inserting the carbon steel mandrel is arranged on the inner wall of the lower cover.

[0026] Further, in Step 3, an upper cover is welded to the upper port of the seamless steel pipe, and a vent hole for vacuum pumping is provided on the upper cover.

[0027] In summary, this application includes at least one of the following beneficial technical effects of the plasticizing barrel for injection molding machines and its manufacturing process:

[0028] 1. By combining the material composition and manufacturing process, the present invention aims to provide excellent wear and corrosion resistance. The superior ratio of nickel and chromium endows the plasticizing barrel with excellent corrosion resistance, while the addition of vanadium and molybdenum enhances its wear resistance, making it perform excellently in humid or corrosive environments;

[0029] 2. The hot isostatic pressing furnace firing technology adopted in the manufacturing process of the present invention ensures the uniformity and density of the alloy material, thereby improving the overall performance of the plasticizing barrel and ensuring the stability and long service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of the manufacturing process flow of the embodiment of this application;

[0031] Figure 2 is a schematic diagram of the external structure of the plasticizing barrel mainly provided by this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to facilitate understanding of the technical means, creative features, achieved purposes and effects of the present invention, the present invention will be further described below with reference to specific embodiments.

[0033] The following is a further detailed description of this application in combination with the attached Figure 1-2 drawings.

[0034] This embodiment provides a wear-resistant and corrosion-resistant plasticizing barrel, and the plasticizing barrel includes raw materials with the following mass fractions:

[0035] Nickel: 60%;

[0036] Chromium: 30%;

[0037] Vanadium: 2%;

[0038] Molybdenum: 1%;

[0039] The rest are binders and unavoidably mixed impurities;

[0040] Among them, the particle size requirements for each metal powder are as follows: Nickel: 20 - 50μm, Chromium: 20 - 50μm, Vanadium: 20 - 50μm, Molybdenum: 15 - 30μm, and other impurities are not more than 90μm; the purity requirements for each metal powder are as follows: Nickel > 99.9%, Chromium 99.5%, Vanadium > 99.65%, Molybdenum > 99.9%.

[0041] High-purity nickel, chromium, and molybdenum can ensure that the product has better mechanical properties and corrosion resistance. At the same time, in order to improve the sintering effect and density of nickel, it is also necessary to pay attention to controlling the particle size and shape of nickel powder. When using 50μm coarse molybdenum powder for pressing, the density is 7.2g / cm3; if using 20μm fine molybdenum powder for pressing, its density can reach 7.4g / cm3. In this embodiment, metal powder with a smaller particle size is selected to increase the density of the alloy.

[0042] A carbon steel core rod is also arranged in the inner cavity of the sol cartridge. The carbon steel core rod is used to enhance the bending strength of the sol cartridge. The carbon content of the carbon steel core rod is between 0.2% and 0.3%, and it has good plasticity and toughness, and can withstand impact and deformation.

[0043] Select a seamless steel pipe cavity that matches the length of the sol cartridge, weld and seal the lower end of the seamless steel pipe, place the carbon steel core rod at the axis of the cavity, inject the mixed powder according to the above mass ratio into the cavity, seal it after compaction, and put it into a hot isostatic pressing furnace. Perform hot isostatic pressing process treatment in a vacuum environment. The rod blank is obtained as a finished sol cartridge after grinding.

[0044] The manufacturing process of a wear-resistant and corrosion-resistant sol cartridge in this embodiment refers to Figure 1 , including the following steps:

[0045] Step 1: Weighing, configure the powder according to the mass fraction required for the above sol cartridge. Through the high-speed rotation of the high-energy ball mill, the metal powder is strongly impacted and rubbed, thereby refining the particles and promoting alloying.

[0046] Step 2: Prepare a seamless steel pipe, weld and seal the lower port of the seamless steel pipe, place the carbon steel core rod at the axis of the cavity, pre-treat the mixed alloy powder and pour it into the cavity of the seamless steel pipe and compact it; weld an end cap on the upper port of the seamless steel pipe, and there is a small hole for vacuuming on the end cap.

[0047] Before loading the alloy powder into the envelope, it is necessary to pre-treat the powder, such as drying, mixing, screening, etc., to ensure the uniformity and fluidity of the powder. At the same time, in order to prevent the powder from oxidizing or volatilizing at high temperatures, it is also necessary to coat a protective film on the surface of the powder.

[0048] Step 3: Weld and seal the blank of the poured alloy powder and evacuate it.

[0049] Step 4: Place the sealed seamless steel pipe into a hot isostatic pressing furnace, gradually heat up to 900 - 1000°C, increase the pressure to 180 - 220MPa, and maintain for no less than 5 hours;

[0050] Step 5: Cool down and reduce pressure, cool with the furnace to room temperature, and take out the alloy rod blank;

[0051] Step 6: Grind the alloy bar stock to make a sol cartridge and conduct quality inspection.

[0052] The present invention also conducts a salt spray test on the finished sol cartridge. The purpose of this salt spray test is to evaluate the corrosion resistance of the sol cartridge to determine its service life and performance stability in harsh environments.

[0053] The test process is as follows:

[0054] This test adopts the internationally common salt spray test method (ASTM B117 - 2013). The sol cartridge is exposed to a salt spray chamber containing sodium chloride and acidic solution, and its corrosion resistance is evaluated by observing and measuring the corrosion degree on the surface of the sol cartridge.

[0055] The temperature in the salt spray test chamber is 35°C, the humidity is above 95%, the brine concentration is 5%, and the spraying time is 72 hours.

[0056] Test results:

[0057] After 72 hours of salt spray test, the sol cartridge was observed and measured. The following are the test results:

[0058] (1) Appearance observation:

[0059] After the salt spray test, the surface of the sol cartridge is bright and there are no signs of corrosion. However, there are obvious corrosion rust marks on the cross - section of the carbon steel mandrel, and the overall appearance of the surface of the sol cartridge still maintains a good gloss.

[0060] (2) Dimension measurement:

[0061] Before and after the test, the length and diameter of the sol cartridge were measured. The results show that the dimensional changes are small and there are no obvious dimensional deformations.

[0062] (3) Mechanical property test:

[0063] The hardness test of the sol cartridge was carried out. First, multiple measurement points on the surface of the sol cartridge after forming and cooling were ground and polished to ensure its flatness, smoothness and no obvious defects; the measurement points were placed on the measuring station of the Rockwell hardness tester, and the hardness value was measured by measuring the imprints at different depths after applying a predetermined load on the material surface.

[0064] The following are the measured data values: HRC60.3 degrees, HRC60.9 degrees, HRC59.7 degrees, HRC59.9 degrees, HRC60.1 degrees, HRC60.1 degrees. The test results show that the mechanical properties have not decreased significantly and still meet the design requirements.

[0065] Conclusion: According to the results of this salt spray test, the sol cartridge exhibits good corrosion resistance in harsh environments. There are no signs of corrosion, the overall appearance and dimensional changes are small, and the mechanical properties have not significantly decreased. Therefore, it can be considered that the sol cartridge is suitable for applications that are long-term exposed to salt spray environments.

[0066] The above are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application shall be covered within the protection scope of this application.

Claims

1. A sol barrel for an injection molding machine, characterized in that: The sol cartridge includes the following raw materials by mass fraction: Nickel: 55%-65%; Chromium: 25%-35%; Vanadium: 1.8%-2.5%; Molybdenum: 0.5%-1.8%; The rest is binder and unavoidable impurities; A carbon steel core rod is also provided in the inner cavity of the sol material cylinder, and the carbon steel core rod is used to enhance the bending strength of the sol material cylinder; Select a seamless steel tube cavity that matches the length of the sol barrel, place a carbon steel core rod into the axis of the cavity, inject the mixed powder according to the above mass ratio into the cavity, compact and seal it and place it into a hot isostatic pressing furnace, perform hot isostatic pressing in a vacuum environment, and obtain a finished sol barrel after processing.

2. A sol barrel for an injection molding machine according to claim 1, characterized in that: The particle size requirements of each metal powder are as follows: nickel: 70-140μm, chromium: 70-140μm, vanadium: 20-50μm, molybdenum: 15-30μm, and other impurities are not larger than 140μm.

3. A sol barrel for an injection molding machine according to claim 1, characterized in that: The purity requirements of each metal powder are as follows: nickel>99.9%, chromium 99.5%, vanadium>99.65%, molybdenum>99.9%.

4. A process for manufacturing a sol barrel for an injection molding machine according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Mixing the ingredients, mixing the powder according to the mass fraction required by the sol barrel and mixing them evenly; Step 2: Prepare a seamless steel pipe with one end sealed, place the carbon steel mandrel into the center of the cavity, pour the mixed alloy powder into the cavity of the seamless steel pipe and compact it; Step 3: Weld and seal the embryo body filled with alloy powder and evacuate it; Step 4: Place the sealed seamless steel pipe into a hot isostatic pressing furnace, gradually increase the temperature to 900-1000°C, increase the pressure to 180-220MPa, and maintain for no less than 5 hours; Step 5: Cool down and reduce pressure, cool to room temperature with the furnace, and take out the alloy bar; Step 6: Grind the alloy rod to make a sol tube and inspect its quality.

5. A sol barrel and manufacturing process for an injection molding machine according to claim 4, characterized in that: The ratio of the outer diameter of the carbon steel core rod to the outer diameter of the alloy rod is 1:

4.

6. A sol barrel and manufacturing process for an injection molding machine according to claim 4, characterized in that: A lower cover is seal-welded to the lower end of the seamless steel pipe, and a positioning seat for positioning and inserting a carbon steel core rod is arranged on the inner wall of the lower cover.

7. A sol barrel and manufacturing process for an injection molding machine according to claim 4, characterized in that: In step three, an upper cover is welded to the upper end of the seamless steel pipe, and a vent hole for vacuuming is provided on the upper cover.

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