A surfacing process for underwater pelletizing cutter manufacturing

Abstract

The present application belongs to the field of polyethylene and polypropylene product granulation in petrochemical industry, and discloses a surfacing processing method for underwater cutting granulation cutter manufacturing, which is used for underwater cutting granulation cutter blade alloying surfacing. By designing alloy powder and adjusting process parameters, the method can prepare long and thin flat long pieces, realize preparation of 70-280mm in length and 3-6mm in thickness, and the hardness is 54-62HRC. Compared with the existing production technology, the surfacing method has higher alloy layer bonding strength after surfacing, lower processing difficulty before and after welding, more than 10 times of production efficiency, and more than 30% of production cost reduction.

Description

Technical Field

[0001] This invention relates to the field of granulation technology for polyethylene and polypropylene products in the petrochemical industry, and in particular to a welding process for manufacturing underwater pelletizing cutters. Background Technology

[0002] In the production process of large-scale continuous extrusion granulators in petrochemicals, the underwater cutter and the granulator template are in a state of continuous relative motion while being in close contact. In order to extend the service life of the cutter, brazing is usually used to weld high wear-resistant cermet materials to stainless steel to make composite ceramic cutters. However, this brazing connection method has excessively high requirements for temperature, vacuum degree, pressure and surface condition of materials, resulting in long cutter manufacturing cycle, low production efficiency and high manufacturing cost of composite cutters.

[0003] To achieve efficient and low-cost manufacturing of composite cutters, this invention proposes a welding process for underwater pelletizing cutters, which can automatically weld high-hardness, wear-resistant, crack-free alloy-formed composite cutters, thus achieving high-efficiency production. Summary of the Invention

[0004] To address the problems in the prior art, this invention proposes a welding process for manufacturing underwater pelletizing cutters. By implementing an alloying welding process on the cutter body, designing the welding process, and automating the operation, the method ensures that the blade layer of the composite cutter meets the requirements of crack-free and wear-resistant performance under operating conditions, thereby increasing production speed and reducing manufacturing costs.

[0005] The technical solution adopted in this invention is as follows: A welding process for manufacturing underwater pelletizing blades, comprising the following steps:

[0006] The first step is to prepare the materials;

[0007] Prepare the blade alloy layer 2 powder and the forging of the cutting blade body 1;

[0008] The second step is to process the cutter body 1;

[0009] Before overlaying the blade alloy layer 2, the cutter body 1 is processed; depending on the different specifications and the number of cutters overlaid each time, a long strip groove with a depth of 3-6mm is processed in the cutter body 1; at least one end of the long strip groove is an arc-shaped structure to ensure that the surface of the long strip groove is flat, free of oxide scale, pores, sand holes, and cracks.

[0010] Step 3: Preheat the cutter body 1;

[0011] Heat the cutter body 1 to 450℃-600℃;

[0012] Step 4: Overlay welding of the blade alloy layer 2;

[0013] Place the cutter body 1 horizontally on the welding worktable, aim the flame gun 3 at the non-welding area of ​​the cutter body 1, ignite the flame gun 3 to supplement the heating of the cutter body 1, adjust the center height so that the surface to be welded inside the long groove of the cutter body 1 can contact the gun head of the cladding welding equipment 4; start the cladding welding equipment 4 to perform cladding welding.

[0014] The cladding welding equipment 4 is a plasma welding equipment or a laser welding equipment;

[0015] When the cladding welding equipment 4 is a plasma welding equipment, the welding process is as follows:

[0016] Start the cladding welding equipment 4, weld in 2-3 layers, and complete the welding in multiple passes for each layer, so as to fill the long strip groove of the cutter body 1. The welding current is between 150 and 170A, the swing amplitude is between 20 and 35mm, the swing speed is between 13 and 15mm / s, and the total thickness of the weld is 5.0-6.5mm. After welding, wrap it with fiber felt to keep it warm and cool slowly.

[0017] When the cladding welding equipment 4 is a laser welding equipment, the welding process is as follows:

[0018] Start the cladding welding equipment 4, with a cladding welding power of 1000-3000W, scanning speed of 2-15mm / s, spot size of 4-6mm, and powder feeding speed of 8-13. Complete the cladding welding in 2-3 layers, with each layer having a thickness of ≤3mm. Weld the long strip groove of the cutter body 1 to fill the gap. The total cladding thickness is 3.0-6.5mm. After welding, wrap the cutter body with a fiber blanket to keep it warm and cool slowly.

[0019] Step 5: Stress-relief annealing;

[0020] After the blade alloy layer 2 is welded, stress-relief annealing is performed. The heat treatment furnace is heated to a holding temperature of 500℃-650℃, and the heating and cooling rates are 40℃-100℃ / h.

[0021] Step 6: Processing and shaping;

[0022] The wire cutting machine is used to cut the material according to the pre-arranged number of cutting blades; the cutting blades are then machined into shape using a CNC milling machine.

[0023] The powder alloy composition of the blade alloy layer 2 is as follows (by mass percentage): Cr 10.0%-20.0%, WC 14.0%-30.0%, Mn 0.1%-5.0%, Mo 0.1%-2.0%, Fe 10.0%-20.0%, with the balance being Ni; the hardness of the blade alloy layer 2 after cladding and welding is 54-62 HRC; the forging material of the cutter body 1 is high-strength stainless steel, with solution strengthening treatment.

[0024] The welding current is a plasma current, and the cladding welding power is a laser beam power.

[0025] The number of cutters used in each welding process is 1 or 2. When there is 1 cutter, they are arranged in one direction of rotation. When there are 2 cutters, they are arranged in two directions of rotation. When the cutter body 1 forging and its groove are multiples of the length, the number of cutters used in each welding process is 2 or 4. When there are 2 cutters, they are arranged in one direction of rotation. When there are 4 cutters, they are arranged in two directions of rotation.

[0026] The beneficial effects of this invention are as follows: Compared with existing production technologies, the welding method described in this invention results in a higher bonding strength between the welded alloy layer and the cutting blade body, a shorter production cycle, increased production efficiency by more than 10 times, and a reduction in production costs by more than 30%. Furthermore, the components prepared by this method are long and thin flat elongated parts, which particularly tests the manufacturing process. This method can achieve the production of components with a diameter of 70-280 mm, a thickness of 3-6 mm, and a hardness of 54-62 HRC. Attached Figure Description

[0027] Figure 1 is a schematic diagram of the composite cutter structure; Figure 1(a) is the front view; Figure 1(b) is the side view; Figure 1(c) is the AA sectional view of Figure 1(a);

[0028] Figure 2 This is a schematic diagram of the cladding welding equipment in operation.

[0029] Figure 3 This is a schematic diagram of the cutting blade body after welding and splitting.

[0030] In the diagram: 1-Cutter body; 2-Blade alloy layer; 3-Flame torch; 4-Clad welding equipment. Detailed Implementation

[0031] A welding process for manufacturing underwater pelletizing blades includes the following steps:

[0032] The first step is to prepare the materials;

[0033] Prepare the blade alloy layer 2 powder and the forging of the cutting blade body 1;

[0034] The second step is to process the cutter body 1;

[0035] Before welding the alloy layer 2 of the blade, the cutter body 1 is machined. Depending on the different specifications and the number of cutters welded each time, a long strip groove with a length of 70-280mm, a width of 10-36mm, and a depth of 3-6mm is machined on the cutter body 1. The specific size of the groove depends on the number of cutters welded at one time, and can be 1, 2, or 4. At least one end of the long strip groove has an arc-shaped structure. Ensure that the surface of the long strip groove is flat, free of oxide scale, pores, sand holes, and cracks.

[0036] Step 3: Preheat the cutter body 1;

[0037] Heat the cutter body 1 to 450℃-600℃;

[0038] Step 4: Overlay welding of the blade alloy layer 2;

[0039] Place the cutter body 1 horizontally on the welding operating table, aim the flame heating gun at the non-welding area of ​​the cutter body 1, and ignite the flame gun 3 to supplement the heating of the cutter body 1. Adjust the center height of the operating table so that the surface to be welded inside the long groove of the cutter body 1 can contact the gun head of the cladding welding equipment 4;

[0040] Option 1: Start the plasma welding equipment 4, with a welding current between 150 and 170A, an amplitude between 20 and 35mm, and an amplitude speed between 13 and 15mm / s. Turn on the flame torch 3 and aim it at the non-welding part of the cutter body 1 to continuously heat the cutter body 1. Complete the welding in 2-3 layers, with each layer having a thickness of ≤3mm. Weld the long strip groove of the cutter body 1 completely, with a total welding thickness of 5.0-6.5mm. After welding, wrap it with a fiber blanket to keep it warm and cool slowly.

[0041] Option 2: Start the laser cladding welding equipment 4, with a power of 1000-3000W, scanning speed of 2-15mm / s, spot size of 4-6mm, and powder feeding speed of 8-13. Complete the cladding in 2-3 layers, with each layer being ≤3mm thick, and fill the long strip groove of the cutter body 1. The total cladding thickness is 3.0-6.5mm. After welding, wrap the area with a fiber blanket for insulation and slow cooling.

[0042] Step 5: Stress-relief annealing;

[0043] After the blade alloy layer 2 is welded, it is heated in a heat treatment furnace for stress relief annealing. The heating rate is 40℃-100℃ / h to heat to 500℃-650℃, hold for 2-4 hours, and then let it cool naturally in the furnace to 100℃ before being taken out of the furnace.

[0044] Step 6: Processing and shaping;

[0045] The wire cutting machine is used to cut the material according to the pre-arranged number of cutting blades; the cutting blades are then machined into shape using a CNC milling machine.

[0046] The forging material of the cutter body 1 is high-strength stainless steel, with solid solution strengthening treatment.

[0047] The powder alloy composition of the blade alloy layer 2 has the following mass percentages: Cr 10.0%-20.0%, WC 14.0%-30.0%, Mn 0.1%-2.0%, Mo 0.1%-2.0%, Fe 10.0%-20.0%, with the balance being Ni; the hardness of the blade alloy layer 2 after cladding welding is 54-62 HRC.

[0048] The flame gun 3 is a natural gas heating device and nozzle.

[0049] The cladding welding equipment 4 is either a plasma cladding welding equipment or a laser cladding welding equipment.

[0050] Example 1

[0051] A welding process for manufacturing underwater pelletizing blades includes the following steps:

[0052] The first step is to prepare the materials;

[0053] Prepare the blade alloy layer 2 powder and the cutting blade body 1 forging; the blade alloy layer 2 powder has the following alloy composition by mass percentage: Cr 13.0%, WC 22.0%, Fe 20%, Mn 0.2%, Mo 0.1%, and the balance Ni; the cutting blade body 1 forging is made of high-strength stainless steel and has undergone solution strengthening treatment.

[0054] The second step is to process the cutter body 1;

[0055] Before welding the blade alloy layer 2, the cutter body 1 is processed; according to different specifications and the number of cutters welded each time, a long strip groove with a depth of 5mm is processed in the cutter body 1, and 2 cutters are welded each time; ensure that the surface of the long strip groove is flat, free of oxide scale, pores, sand holes, and cracks.

[0056] Step 3: Preheat the cutter body 1;

[0057] Heat the cutter body 1 to 450℃;

[0058] Step 4: Overlay welding of the blade alloy layer 2;

[0059] Place the cutter body 1 horizontally onto the workpiece on the welding worktable. Heat the flame torch 3 to supplement the heating of the cutter body 1. Adjust the center height so that the surface to be welded inside the long groove of the cutter body 1 can contact the torch head of the cladding welding equipment 4.

[0060] Start the cladding welding equipment 4 and complete the welding in two stages to fill the long groove of the cutter body 1. The plasma current is 150A, the swing amplitude is 30mm, the swing speed is 13mm / s, and the total thickness of the welding is 5.5mm. After welding, wrap it with a fiber blanket to keep it warm and cool slowly.

[0061] Step 5: Stress-relief annealing;

[0062] After the blade alloy layer 2 is welded, stress-relief annealing is performed, and the heat treatment furnace is heated to a holding temperature of 650℃, with a heating and cooling rate of 100℃ / h.

[0063] Step 6: Processing and shaping;

[0064] The cutting is performed using a wire EDM machine according to the pre-arranged number of cutting blades; the cutting blade body is then machined into two 140mm long cutting blades with a blade thickness of 3mm and a hardness of 56±2HRC using a CNC milling machine.

[0065] Example 2

[0066] A welding process for manufacturing underwater pelletizing blades includes the following steps:

[0067] The first step is to prepare the materials;

[0068] Prepare the blade alloy layer 2 powder and the cutting blade body 1 forging; the blade alloy layer 2 powder has the following alloy composition by mass percentage: Cr 13.0%, WC 22.0%, Fe 20.0%, Mn 0.2%, Mo 0.2%, and the balance Ni; the cutting blade body 1 forging is made of high-strength stainless steel and has undergone solution strengthening treatment.

[0069] The second step is to process the cutter body 1;

[0070] Before welding the blade alloy layer 2, the cutter body 1 is processed; according to different specifications and the number of cutters welded each time, a long strip groove with a depth of 5mm is processed in the cutter body 1, and the number of cutters welded each time is 2; ensure that the surface of the long strip groove is flat, free of oxide scale, pores, sand holes, and cracks.

[0071] Step 3: Preheat the cutter body 1;

[0072] Heat the cutter body 1 to 600℃;

[0073] Step 4: Overlay welding of the blade alloy layer 2;

[0074] Place the cutter body 1 horizontally on the welding worktable, heat the flame torch 3, and ignite the flame torch 3 to supplement the heating of the non-welding area of ​​the cutter body 1. Adjust the height of the laser torch head so that the surface to be welded inside the long groove of the cutter body 1 can contact the torch head of the cladding welding equipment 4;

[0075] Start the laser cladding welding equipment 4, and complete the welding in 3 layers and multiple passes to fill the long strip groove of the cutter body 1. The power is 1500W, the scanning speed is 6mm / s, the spot size is 4mm, and the powder feeding speed is 11. The long strip groove of the cutter body 1 is filled with welding, and the total welding thickness is 5.0mm. After welding, wrap it with a fiber blanket for heat preservation and slow cooling.

[0076] Step 5: Stress-relief annealing;

[0077] After the blade alloy layer 2 is welded, stress-relieving annealing is performed, and the heat treatment furnace is heated to a holding temperature of 650℃, with a heating and cooling rate of 80℃ / h.

[0078] Step 6: Processing and shaping;

[0079] The cutting is performed using a wire EDM machine according to the pre-arranged number of cutting blades; the cutting blades are then machined into two 140mm long cutting blades with a blade thickness of 3mm and a hardness of 56±2HRC using a CNC milling machine.

[0080] Example 3

[0081] A welding process for manufacturing underwater pelletizing blades includes the following steps:

[0082] The first step is to prepare the materials;

[0083] Prepare the blade alloy layer 2 powder and the cutting blade body 1 forging; the blade alloy layer 2 powder has the following alloy composition by mass percentage: Cr 14.0%, WC 17.0%, Fe 18%, Mn 0.1%, Mo 0.1%, and the balance Ni; the cutting blade body 1 forging is made of high-strength stainless steel and has undergone solution strengthening treatment.

[0084] The second step is to process the cutter body 1;

[0085] Before welding the blade alloy layer 2, the cutter body 1 is processed; according to different specifications and the number of cutters welded each time, a long strip groove with a depth of 5mm is processed in the cutter body 1, and 4 cutters are welded each time; ensure that the surface of the long strip groove is flat, free of oxide scale, pores, sand holes, and cracks.

[0086] Step 3: Preheat the cutter body 1;

[0087] Heat the cutter body 1 to 450℃;

[0088] Step 4: Overlay welding of the blade alloy layer 2;

[0089] Place the cutter body 1 horizontally on the welding worktable, heat the flame torch 3, and ignite the flame torch 3 to supplement the heating of the cutter body 1. Adjust the center height so that the surface to be welded inside the long groove of the cutter body 1 can contact the torch head of the cladding welding equipment 4;

[0090] Start the plasma welding equipment and complete the welding in two stages to fill the long groove of the cutter body 1. The plasma current is 160A, the swing amplitude is 26mm, the swing speed is 15mm / s, and the total thickness of the weld is 6.0mm. After welding, wrap it with a fiber blanket to keep it warm and cool slowly.

[0091] Step 5: Stress-relief annealing;

[0092] After the blade alloy layer 2 is welded, stress-relieving annealing is performed, and the heat treatment furnace is heated to a holding temperature of 560℃, with a heating and cooling rate of 70℃ / h.

[0093] Step 6: Processing and shaping;

[0094] The cutting is performed using a wire EDM machine according to the pre-arranged number of cutting blades; the cutting blades are then machined into four pieces using a CNC milling machine, each 140mm long, 3mm thick, and with a hardness of 56±2HRC.

[0095] Comparative Example 1

[0096] Based on Example 1, the cutter body 1 in the third step is heated to 200°C and the rest is the same as in Example 1. The result of the overlay welding is that microcracks appear in the weld bead and the blade will chip off, affecting its use.

[0097] Comparative Example 2

[0098] Based on Example 1, when the plasma current in the fourth step is set to 175A, the rest is the same as in Example 1. The result after welding is that the hardness of the weld bead is 44-46HRC, which is low and the wear resistance of the blade is not enough.

[0099] Comparative Example 3

[0100] Based on Example 1, the powder alloy composition of the blade alloy layer 2 has the following mass percentages: Cr 10.0%, WC 37.0%, Fe 9.0%, Mn 0.1%, Mo 0.1%, and the balance Ni. Due to the increased WC content, this powder alloy composition leads to more cracks in the welded alloy blade and a decrease in wear resistance.

Claims

1. A welding process for manufacturing underwater pelletizing blades, characterized in that, The steps include the following: The first step is to prepare the materials; Prepare the blade alloy layer (2) powder and the cutter body (1) forging; The second step is to process the cutter body (1). Before overlaying the blade alloy layer (2), the cutter body (1) is processed; according to different specifications and the number of cutters overlaid each time, a long groove with a depth of 3-6mm is processed in the cutter body (1); at least one end of the long groove is an arc-shaped structure to ensure that the surface of the long groove is flat, free of oxide scale, pores, sand holes, and cracks. Third step, preheat the cutter body (1); Heat the cutter body (1) to 450℃-600℃; Step 4: Overlay welding of the blade alloy layer (2); Place the cutter body (1) horizontally on the welding workbench, aim the flame gun (3) at the non-welding area of ​​the cutter body (1), ignite the flame gun (3) to supplement the heating of the cutter body (1), adjust the center height so that the surface to be welded inside the long groove of the cutter body (1) can contact the gun head of the cladding welding equipment (4); Start the cladding welding equipment (4) to perform cladding welding; The cladding welding equipment (4) is a plasma welding equipment or a laser welding equipment; When the cladding welding equipment (4) is a plasma welding equipment, the welding process is as follows: Start the cladding welding equipment (4), weld in 2-3 layers, and complete the welding in multiple passes for each layer. Weld the long groove of the cutter body (1) to the full. The welding current is between 150 and 170A, the swing amplitude is between 20 and 35mm, the swing speed is between 13 and 15mm / s, and the total thickness of the weld is 5.0-6.5mm. After welding, wrap it with fiber felt to keep it warm and cool slowly. When the cladding welding equipment (4) is a laser welding equipment, the welding process is as follows: Start the cladding welding equipment (4), the cladding welding power is 1000-3000W, the scanning speed is 2-15mm / s, and the spot size is 4-6mm; complete the cladding welding in 2-3 layers, each layer is ≤3mm thick, and fill the long groove of the cutter body (1) with welding. The total cladding thickness is 3.0-6.5mm. After welding, wrap it with a fiber blanket to keep it warm and cool slowly. Step 5: Stress-relief annealing; After the blade alloy layer (2) is welded, stress relief annealing is performed. The heat treatment furnace is heated to a holding temperature of 500℃-650℃, and the heating and cooling rates are 40℃-100℃ / h. Step 6: Processing and shaping; The wire cutting machine is used to cut the material according to the pre-arranged number of cutting blades; the cutting blades are then machined into shape using a CNC milling machine.

2. The welding process for manufacturing underwater pelletizing blades according to claim 1, characterized in that, The blade alloy layer (2) powder composition by mass percentage is as follows: Cr element mass percentage is 10.0%-20.0%, WC mass percentage is 14.0%-30.0%, Mn element mass percentage is 0.1%-2.0%, Mo element mass percentage is 0.1%-2.0%, Fe element mass percentage is 10.0%-20.0%, and the balance is Ni; the blade alloy layer (2) after cladding and welding has a hardness of 54-62 HRC; the cutting blade body (1) forging material is high-strength stainless steel, with solid solution strengthening treatment.

3. The welding process for manufacturing underwater pelletizing blades according to claim 1 or 2, characterized in that, The welding current is a plasma current, and the cladding welding power is a laser beam power.

4. The welding process for manufacturing underwater pelletizing blades according to claim 3, characterized in that, The number of cutters used in each welding process is one or two. When there is one cutter, they are arranged in one direction of rotation. When there are two cutters, one is arranged in each of two directions of rotation. When the length of the forging of the cutter body (1) and its groove is multiple of the length, the number of cutters welded each time is 2 or 4. When there are 2, they are arranged in one direction of rotation. When there are 4, they are arranged in two directions of rotation.

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