High-vanadium cast iron lining manufacturing device of double-screw plastic extruding machine

Abstract

The utility model discloses a high-vanadium cast iron lining manufacturing device of a double-screw plastic extruding machine, and belongs to the technical field of lining production. The manufacturing device comprises risers and a riser patch which are arranged side by side, wherein a bushing cavity is longitudinally arranged between every two adjacent risers; the middle riser is connected with a straight pouring gate and a transverse pouring gate, and other risers are connected with the straight pouring gate in parallel and are all connected with the transverse pouring gate; flow gates are arranged at the bottoms of the risers opposite to the side surfaces of the bushing cavities; the two side faces of the riser patch are tightly attached to the inner pouring gate and the lining cavity respectively, the riser patch is arranged between the inner pouring gate and the lining cavity, and the flow and the flow direction of molten iron during pouring are guided through riser patch edge cavities in the two sides of the formed lining cavity; and during pouring, high-vanadium cast iron molten iron is adopted for pouring, the wear resistance of the bushing casting is improved, the wear resistance is 2.5-3 times that of an existing bushing product made of high-chromium cast iron, meanwhile, the bushing casting has excellent toughness, the problem of internal looseness of the bushing casting is solved, the shock resistance of the bushing product is improved, and the service life of the bushing product is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of bushing production, in particular to a manufacturing device for high-vanadium cast iron bushings of a twin-screw extruder. Background Art

[0002] With the rapid development of the global rubber and plastics, chemical, wood plastic, building materials and other industries, these industries are equipped with twin-screw extruders in large quantities. Bushings are easy-to-wear accessories of twin-screw extruders and are required to have excellent processability, extremely high wear resistance and toughness.

[0003] At present, the bushing materials of twin-screw extruders are generally W6Mo5Cr4V2 high-speed steel and KMTBCr26 high-chromium cast iron. High-speed steel has high material and manufacturing costs, a long production cycle, and insufficient wear resistance, which leads to frequent component replacement and production delays. Although bushings made of KMTBCr26 material have low production costs and high efficiency, their wear resistance and toughness cannot meet the production requirements of high-strength production conditions such as reinforced nylon. Glass fiber is added to reinforced nylon during production. The greater the amount of glass fiber added, the greater the wear on the plasticizing components of the extruder and injection molding machine. Severe wear and frequent replacement of plasticizing components have affected the production of enterprises. The market demands an upgraded product with high strength and high wear resistance.

[0004] Bushings produced by casting process Figure 1 As shown, it includes a bushing body 10 and a bushing inner hole 11 that passes through it laterally. The middle part of the bushing inner hole 11 is a feeding part 12. The feeding part 12, as the name suggests, usually requires the use of a riser for feeding. The current feeding method cannot completely solve the looseness inside the casting; and the bushing inner hole 11 is a key use part. The looseness of the inner hole (small holes) will not only reduce its service life, but also affect the cleanliness of the raw material (if there are holes in the bushing inner hole 11, when producing material A, material A will remain in the hole, affecting the color and performance of material B produced next time). Utility Model Content

[0005] 1. Technical problems to be solved by the utility model:

[0006] In view of the problems that the bushings produced by the existing casting process have poor strength and wear resistance, and the looseness inside the casting leads to a short service life and affects the cleanliness of the extruded raw materials, the utility model provides a high-vanadium cast iron bushing manufacturing device for a twin-screw extruder. By adding a special riser subsidy to the bushing manufacturing device, the side cavity formed by the riser subsidy guides the flow rate and direction of the molten iron during pouring, thereby achieving the purpose of all-round dense, uniform and microporous bushing casting.

[0007] 2. Technical solution:

[0008] In order to achieve the above-mentioned purpose, the technical solution provided by the present utility model is:

[0009] A manufacturing device for a high-vanadium cast iron bushing for a twin-screw extruder comprises risers arranged side by side, with a bushing cavity longitudinally arranged between two adjacent risers; the middle riser is connected to a sprue and a runner, and the other risers and the sprue are in parallel and are all connected to the runner; an ingode is arranged at the bottom of the riser facing the side of the bushing cavity, and a mud core adapted to the size and shape of the bushing is provided inside the bushing cavity, and the device also comprises a riser subsidy, the two sides of the riser subsidy are respectively close to the ingode and the bushing cavity, and a riser subsidy is arranged between the ingode and the bushing cavity, and the flow rate and direction of molten iron during pouring are guided by the riser subsidy side cavities on both sides of the bushing cavity after molding, thereby at least solving the technical problems of low service life caused by looseness inside the bushing casting and affecting the cleanliness of the extruded raw materials.

[0010] A further technical solution is to provide riser compensation in the form of an arc-shaped segment with thickness gradually decreasing from the middle to the upper and lower sides, so as to guide the flow rate and direction of molten iron during pouring and achieve a full range of shrinkage compensation effect.

[0011] A further technical solution is that the riser subsidy includes an integrally connected subsidy middle section and subsidy transition sections on its upper and lower sides; the subsidy middle section is a rectangular section, and the subsidy transition section is a semi-arc section with a thickness gradually decreasing toward both sides, and the curvature is respectively adapted to the upper and lower parts of the bushing cavity.

[0012] A further technical solution is that an air vent is vertically fixed at the end of the mud core to further guide the flow rate and direction of molten iron during pouring, and is conducive to the exhaust of the mud core and prevents the air vent from entering the mold cavity.

[0013] Further casting structure, the width L of the riser subsidy is 1 / 4 to 1 / 3 of the length of the bushing cavity; the thickness H of the middle section of the subsidy is 2 / 5 to 1 / 2 of the thickness of the thin-wall position of the bushing.

[0014] A method for manufacturing a high-vanadium cast iron bushing for a twin-screw extruder, comprising the following steps:

[0015] Smelting high vanadium cast iron alloy into molten iron;

[0016] After the mold box including the manufacturing device is subjected to sand mixing, sand molding and box assembly, a bushing cavity is formed inside the molding sand, and side cavities in the shape of risers are formed on both sides of the bushing cavity;

[0017] During pouring, after the molten iron passes through the sprue and the runner and fills the bushing cavity and the side cavities on both sides thereof, the side cavities widen the flow channel of the molten iron to the highest point of the bushing cavity and on both sides of its length direction, and can transport more molten iron to the highest point and on both sides of its length direction, making the flow of molten iron smoother, guiding the flow rate and direction of molten iron during pouring, and thereby achieving the technical effect of making the bushing body all-round dense, uniform and free of micropores.

[0018] The manufacturing method further provides that the high-vanadium-chromium iron molten iron composition is 2.6-3.1% C, 0.4-1.2% Si, 0.4-1.0% Mn, ≤0.03% P, ≤0.03% S, 4-6% Cr, 0.8-1.5% Mo, and 8-11% V; the balance is Fe and other trace elements. The addition of high V content forms very hard carbides (VC), which are essentially spherical in shape. The high hardness improves wear resistance, and the spherical shape reduces the chance of fracture of the matrix, thus meeting the product's requirements for wear resistance and toughness. The corresponding molybdenum content forms Mo2C, which often occurs as a eutectic component, significantly improving the wear resistance of the high-chromium cast iron.

[0019] The manufacturing method for high-vanadium ferrochrome is to add low-carbon steel and pig iron first, followed by ferromolybdenum and roasted high-carbon ferrochrome, and finally ferrovanadium. Ferrovanadium is easily burned and oxidized, so it is added last. When melting molten steel in an intermediate frequency furnace, adding the molten materials in the order of easy first and difficult later helps reduce the difficulty of melting the alloying materials, saving smelting time and energy consumption, thereby lowering production costs.

[0020] A further manufacturing method is to tap the molten iron at 1550-1650℃, and add silicon, manganese and 0.1% aluminum wire for deoxidation before tapping the molten iron; because the V element is an active metal element and easily reacts with oxygen at high temperature, effective deoxidation is conducive to the smooth pouring and filling of the molten iron and the solidification and molding of the casting.

[0021] A further manufacturing method is to pour at a speed of 2.5 to 3.0 kg / s, and to achieve a pouring temperature of 1500 to 1550° C. for the molten iron to be poured into the bushing cavity (1). Since high-vanadium cast iron is prone to forming an oxide film, the pouring temperature of 1500 to 1550° C. can improve the fluidity of the molten iron and allow for rapid pouring, thereby preventing defects such as cold shut wrinkles and insufficient pouring.

[0022] 3. Beneficial effects:

[0023] Compared with the prior art, the technical solution provided by this utility model has the following beneficial effects:

[0024] (1) The utility model relates to a manufacturing device for a high-vanadium cast iron bushing for a twin-screw extruder. The device solves the loosening problem of the high-vanadium cast iron bushing for a twin-screw extruder by adding an external subsidy. The device also increases the riser subsidy to guide and widen the flow channel of the molten iron to the highest point and the farthest end. This allows for more molten iron to reach the highest point and the farthest end, thereby achieving the technical effect of all-round shrinkage compensation for the bushing and a dense interior without micropores.

[0025] (2) The high vanadium cast iron bushing of the twin-screw extruder of the utility model is cast with high vanadium cast iron molten iron, which can improve the wear resistance of the bushing casting. The wear resistance is 2.5 to 3 times that of the bushing products made of W6Mo5Cr4V2 high-speed steel and KMTBCr26 high chromium cast iron. At the same time, it has excellent toughness, improves the impact resistance of the bushing product, and meets the use requirements of the bushing product in a high-intensity working environment. The use effect is obvious, the replacement frequency of the bushing is reduced by more than half, the work efficiency is significantly improved, the cost is saved and the production capacity is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a high-vanadium cast iron bushing for a twin-screw extruder in the prior art;

[0027] Figure 2 It is a schematic structural diagram of a twin-screw extruder bushing manufacturing device in the prior art;

[0028] Figure 3 for Figure 2 Schematic diagram of the local structure;

[0029] Figure 4 A schematic structural diagram of a high-vanadium cast iron bushing manufacturing device for a twin-screw extruder according to a specific embodiment;

[0030] Figure 5 It is a schematic diagram of the bushing cavity and riser patch structure of a specific embodiment.

[0031] Figure 6 for Figure 4 A side structural diagram of

[0032] Figure 7 It is a schematic structural diagram of a high vanadium cast iron bushing for a twin-screw extruder according to a specific embodiment.

[0033] In the figure: 1. Bushing cavity; 2. Riser subsidy; 3. Riser; 5. Mud core; 6. Straight runner; 7. Horizontal runner; 10. Bushing body; 11. Bushing inner hole; 12. Shrinkage compensation part; 20. Riser subsidy raised section; 21. Subsidy middle section; 22. Subsidy transition section; 31. Ingate; 51. Vent. DETAILED DESCRIPTION

[0034] In order to further understand the content of the utility model, the utility model is described in detail with reference to the accompanying drawings.

[0035] Example 1

[0036] The manufacturing device of the high vanadium cast iron bushing of the twin-screw extruder of this embodiment is as follows Figure 4As shown, it includes risers 3 arranged side by side, usually three risers 3 arranged side by side form a group; a bushing cavity 1 is longitudinally arranged between two adjacent risers 3; the middle riser 3 is connected to a sprue 6 and a runner 7, and the other risers 3 and the sprue 6 are in parallel and are all connected to the runner 7; an endogate 31 is arranged at the bottom of the riser 3 facing the side of the bushing cavity 1, and the inside of the bushing cavity 1 is a mud core 5 adapted to the size and shape of the bushing, and also includes a riser subsidy 2, and the two sides of the riser subsidy 2 are respectively close to the endogate 31 and the bushing cavity 1. The riser subsidy 2 is an arc-shaped segment with a thickness gradually decreasing from the middle to the upper and lower sides, so as to guide the flow rate and direction of the molten iron during pouring and achieve a full range of shrinkage compensation effect. The riser subsidy 2 includes an integrally connected subsidy middle section 21 and subsidy transition sections 22 on its upper and lower sides; the subsidy middle section 21 is a rectangular section, and the subsidy transition section 22 is a semi-arc section with a thickness gradually decreasing toward both sides, and the curvature is adapted to the upper and lower parts of the bushing cavity 1 respectively. An air vent 51 is vertically fixed at the end of the mud core 5 to further guide the flow and direction of the molten iron during pouring, and is beneficial to the exhaust of the mud core and prevents the air vent from entering the cavity. Figure 5 、 6 As shown, the width L of the riser patch is 1 / 4 to 1 / 3 of the bushing cavity length; the thickness H of the middle section of the patch is 2 / 5 to 1 / 2 of the thickness of the bushing's thin-walled area, effectively guiding both the flow rate and direction of molten iron pouring. For example, when manufacturing a 95-model twin-screw extruder bushing, the width L of the riser patch 2 is preferably 125 mm, and the thickness H of the middle section 21 of the patch is preferably 8 mm, achieving optimal flow and direction guidance for molten iron pouring into the bushing cavity 1 without blind spots.

[0037] The manufacturing method of the high vanadium cast iron bushing for a twin-screw extruder of this embodiment is to make a bushing of the 95 model of a twin-screw extruder, and the steps are as follows:

[0038] Step 1: After the mold box including the above manufacturing device is subjected to sand mixing, sand molding and box assembly, a hollow cavity structure of the bushing cavity 1 is formed inside the molding sand, and side cavities in the shape of riser patches 2 are generated on both sides of the bushing cavity 1;

[0039] Step 2: During pouring, the molten iron pouring temperature is 1500-1550℃. After the molten iron enters the bushing cavity 1 and the side cavities on both sides through the runner 6, the pouring structure relaxes the molten iron flow channel to the highest point of the bushing cavity 1 and the far ends on both sides of its length direction.

[0040] like Figure 2 、 3 As shown, the side casting mold of the prior art has Figure 3 Except for the riser direct feeding part 12 in the red circle, the other parts of the bushing cavity 1 are all thin-walled. Although the riser feeding part 12 is relatively thick, it is difficult for the riser to feed the thin-walled parts at the highest point and the farthest end of the product. Figure 4 、5 As shown in Figure 6, the high vanadium cast iron bushing manufacturing device for the twin-screw extruder of this embodiment increases the thickness of the product at the riser 3 by adding the riser subsidy 2, so that the molten iron at this part gradually solidifies slowly from the middle to both sides, and then this part of the molten iron is pushed to the highest point and the farthest thin-wall position in stages. The molten iron pouring temperature is 1500-1550℃, which cooperates with the special pouring structure to enable the molten iron to be transported in stages along the semi-arc-shaped subsidy transition section 22 to reach the highest point and both sides of its length direction, so that the flow of molten iron is smoother, and then the flow rate and flow direction of the molten iron during pouring are guided to the bushing cavity 1 without dead angles.

[0041] The twin-screw extruder high vanadium cast iron bushing manufacturing device of this embodiment sets a riser subsidy 2 between the inner gate 31 and the bushing cavity 1 during the production of the bushing. The riser subsidy 2 side cavities on both sides of the bushing cavity 1 after molding are used to guide the flow rate and direction of molten iron pouring, thereby at least solving the technical problems of the loose interior of the bushing casting resulting in a short service life and affecting the cleanliness of the extruded raw materials.

[0042] Example 2

[0043] The twin-screw extruder high vanadium cast iron bushing manufacturing device of this embodiment has the same basic structure and bushing manufacturing steps as Example 1, and the difference or improvement is that the air outlet 51 is in the shape of a cone that closes upward, which plays a role in collecting and concentrating air, and further guides the flow rate and direction of molten iron pouring through the air pressure flow direction.

[0044] The molten iron is molten iron obtained by smelting a high-vanadium cast iron alloy, and the composition of the molten iron after smelting is 2.6-3.1% C, 0.4-1.2% Si, 0.4-1.0% Mn, ≤0.03% P, ≤0.03% S, 4-6% Cr, 0.8-1.5% Mo, 8-11% V, and the balance is Fe and other trace elements. In this embodiment, preferably 2.8% C, 0.8% Si, 0.7% Mn, ≤0.01% P, ≤0.01% S, 6% Cr, 1.3% Mo, 10% V, and the balance is Fe and other trace elements. Compared to the existing bushing iron composition, the addition of chromium-containing cast iron, a highly wear-resistant cast iron, and a relatively high content of 8-11% vanadium are added. Vanadium and vanadium are strong carbide-forming elements. In the as-cast state, 8-11% vanadium not only forms primary carbides that refine the alloy structure of the high-chromium cast iron and stabilize its carbides, but also forms secondary carbides, making it easier to obtain martensite in the as-cast state. The extremely small vanadium carbide particles are evenly distributed in the microstructure, significantly improving the wear resistance of the high-chromium cast iron. The addition of high vanadium content forms very hard carbides (VC). These carbides are essentially spherical in shape. The high hardness improves wear resistance, and the spherical shape reduces the matrix's fracture, thus meeting the product's requirements for wear resistance and toughness. The addition of an appropriate amount of molybdenum effectively ensures the hardenability of the casting. Molybdenum can also form Mo2C, mostly in the form of a eutectic component, which is very beneficial to the wear resistance of the high-chromium cast iron.

[0045] The specific steps of manufacturing are:

[0046] Step 1: Melt the high-vanadium cast iron alloy into molten iron: The order of adding materials to the high-vanadium chromium iron molten iron is to add low-carbon steel and pig iron first, then add ferromolybdenum and roasted high-carbon ferrochrome, and finally add ferrovanadium; ferrovanadium is easy to burn and oxidize, so it is added last. When using a medium-frequency furnace to melt molten steel, adding the smelting materials in the order of easy first and difficult later is beneficial to reducing the difficulty of melting the alloy materials in the material, saving smelting time and reducing energy loss, thereby reducing production costs; molten iron is discharged at 1550-1650℃, and silicon, manganese and 0.1% aluminum wire are added before the molten iron is discharged for deoxidation; because the V element is an active metal element, it is easy to react with oxygen at high temperature, and effective deoxidation is beneficial to the smooth pouring and filling of molten iron and the solidification and forming of castings;

[0047] Step 2: Sand mixing. The properties of the sand are controlled at 5.5-6.5% moisture, 110-140% air permeability, 120-150kPa wet compressive strength, and 38-42% compaction rate.

[0048] Step 3: Manufacturing the device mold, including sand mixing, sand casting and box assembly, forming a hollow cavity structure of the bushing cavity 1 inside the molding sand, and generating side cavities in the shape of riser patches 2 on both sides of the bushing cavity 1;

[0049] Step 4: pouring, including pouring with high-vanadium-chromium iron molten iron, the molten iron enters the sleeve cavity 1 of the barrel sleeve of the twin-screw extruder through the sprue 6, the cross runner 7, the riser runner and the inner gate 31 until the molten iron completely fills the sleeve cavity 1; the pouring speed is 2.5-3.0 kg / s, and the pouring temperature of the molten iron reaches 1500-1550°C to the sleeve cavity 1. Since high-vanadium cast iron is prone to form an oxide film, the pouring temperature of 1500-1550°C can improve the fluidity of the high-vanadium-chromium iron molten iron and quickly pour it to prevent defects such as cold shut wrinkles and insufficient pouring.

[0050] Step 5: Unpack after 4 hours of heat preservation. Keep the heat preservation site dry to prevent the casting from cracking.

[0051] Step 6: Beat the box to drop the sand, which includes knocking the box to vibrate it, so that the sand and the casting fall together, and the mud core 5 also collapses and falls off at the same time, and then the casting is taken out with a hook;

[0052] Step 7: Remove the side riser 3;

[0053] Step 8: Shot blasting, using a hook-type shot blasting machine to perform shot blasting to obtain a high-vanadium cast iron bushing for a twin-screw extruder;

[0054] like Figure 7 As shown, the obtained high-vanadium cast iron bushing for a twin-screw extruder includes a bushing body 10 and a bushing inner hole 11 that passes through the bushing body 10 transversely. It also includes riser-subsidized protruding sections 20 that are symmetrically side-casted on both sides of the middle of the bushing body 10. The riser-subsidized protruding sections 20 are generated after the molten iron fills the side cavity in the shape of the riser-subsidized 2. The shape and size of the riser-subsidized protruding sections 20 are adapted to the shape of the riser-subsidized 2. The riser-subsidized protruding sections 20 are arc-shaped sections whose thickness gradually decreases from the middle to the upper and lower sides. The curvature is adapted to the upper and lower parts of the bushing body 10, respectively. By compensating the shrinkage of the casting through the riser-subsidized 2 and using high-vanadium cast iron for casting, not only can the quality of the bushing be improved and surface cracking be reduced, but also the generation of shrinkage cavities and shrinkage can be effectively prevented, and the strength, impact toughness and wear resistance of the bushing casting can be improved.

[0055] Through cross-sectional metallographic examination, the bushing of the twin-screw extruder model 95, which is manufactured by the corresponding casting process using the above casting structure, has a dense and uniform overall internal structure without obvious micropores; its wear resistance is 2.5 to 3 times that of bushing products made of W6Mo5Cr4V2 high-speed steel and KMTBCr26 high-chromium cast iron. At the same time, it has excellent toughness, which improves the impact resistance of the bushing product and meets the use requirements of the bushing product in high-intensity working environments. The use effect is obvious, and the replacement frequency of the bushing is reduced by more than half.

[0056] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure and manufacturing steps are not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the inventive purpose of the present invention, designs a structure and embodiment similar to the technical solution without creatively designing, they shall fall within the scope of protection of the present invention.

Claims

1. A manufacturing device for a high-vanadium cast iron bushing for a twin-screw extruder, comprising risers (3) arranged side by side, a bushing cavity (1) being longitudinally arranged between two adjacent risers (3); the middle riser (3) being connected to a sprue (6) and a runner (7), the other risers (3) and the sprue (6) being in parallel relation, and all being connected to the runner (7); an inner gate (31) being arranged at the bottom of the riser (3) facing the side of the bushing cavity (1), and a mud core (5) being adapted to the size and shape of the bushing inside the bushing cavity (1), characterized in that: It also includes a riser patch (2), and the two side surfaces of the riser patch (2) are respectively close to the inner gate (31) and the bushing cavity (1).

2. The manufacturing device for high vanadium cast iron bushings for twin-screw extruders according to claim 1, characterized in that: The riser patch (2) is an arc-shaped segment whose thickness gradually decreases from the middle to the upper and lower sides.

3. The manufacturing device according to claim 2, characterized in that: The riser subsidy (2) comprises an integrally connected subsidy middle section (21) and subsidy transition sections (22) on its upper and lower sides; the subsidy middle section (21) is a rectangular section, and the subsidy transition section (22) is a semi-arc section with a thickness gradually decreasing toward both sides, and the curvature is respectively adapted to the upper and lower parts of the bushing cavity (1).

4. The manufacturing device according to any one of claims 1 to 3, characterized in that: An air outlet (51) is vertically fixed at the end of the mud core (5).

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