Hydraulic support push rod welding method for Q890-grade steel plate with low cold crack sensitivity

Abstract

According to the hydraulic support push rod welding method for the Q890-grade steel plate with the low cold crack sensitivity, the Q890-grade steel plate with the low cold crack sensitivity and the low carbon component is used instead, the cold crack sensitivity index Pcm of the steel plate is smaller than or equal to 0.23%, the carbon content of the steel plate is smaller than or equal to 0.10%, the tempering temperature of the steel plate is 480 DEG C or above, and the cold crack effect is not obvious; laser cutting blanking is adopted, so that the deformation problem of flame cutting is avoided; common-edge cutting blanking is adopted, so that the generation of waste materials is reduced; the requirement of the steel for the preheating temperature is lowered, and cold cracks are avoided; a symmetrical welding mode is adopted to ensure that welding deformation is smaller; and a groove welding process is replaced by a fillet welding process, so that the assembly difficulty is reduced, and the assembly efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine hydraulic supports, and in particular to a method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity. Background Art

[0002] The push rod is one of the key components of the hydraulic support. It serves as the connection between the hydraulic support body and the scraper conveyor. It has the characteristics of large welding volume, poor service conditions, large load-bearing capacity, and complex force. It is welded from high-strength steel parts below Q890 level such as main reinforcement, main reinforcement plate, reinforcement plate, cover plate, etc. The thickness of the parts is mostly 20, 25, and 30 mm.

[0003] All parts on the push rod are connected by welding, and the weld forms are mainly fillet welds and groove welds. The key welds are the groove welds formed between the 40° groove of the main reinforcement plate and the cover plate, and the fillet welds formed between the main reinforcement plate and the bottom plate.

[0004] The traditional large working resistance hydraulic support push rod adopts the offline quenched and tempered medium carbon content Q890 high-strength steel plate. The production process is: cutting → leveling → cutting groove → primary assembly → primary welding → secondary assembly → secondary welding → flame correction → painting. The details of the process plan are shown below.

[0005] Step (1) Cutting: Use flame cutting machine to cut the shape of each push rod part, and manually polish the surface oxide scale and cutting slag of the parts; Step (2) Leveling: Use a flatbed machine to level parts with a length of more than 600 mm. After the flatness meets the requirements, proceed to the bevel cutting process; Step (3) Cutting the groove: Use a plasma cutting robot to cut the grooves of the parts with grooves, and use a grinder to grind the parts with welds on each part to reveal the metallic luster; Step (4) One-time assembly: Mark the position lines of the main reinforcement, rib plate and other parts on the bottom plate, use the tooling to place the main reinforcement and rib plate on the bottom plate, adjust the position of each part, and use ER50-6 welding wire to perform single-layer single-pass manual positioning welding at the position required by the process; Step (5) Primary welding: Fix the push rod on the welding platform, weld the internal weld and the bottom weld, first perform the overall base welding by manual welding, then use the robot to perform the filling and cover welding in sequence, and preheat the whole to 100-120℃ before welding; Step (6) Secondary assembly: Manually use lifting equipment to sink the cover plate between the main reinforcements. First adjust the front, back, left, and right assembly gaps to ensure that the gaps are uniform. Finally, adjust the sinking depth to ensure that the surface of the cover plate is about 5mm below the upper end surface of the main reinforcement. Use ER50-6 welding wire to perform single-layer single-pass manual positioning welding at the position required by the process. Step (7) Secondary welding: After the cover plate is assembled, first perform manual welding for overall base, then use the robot to perform filling and cover welding in sequence. After the cover plate groove is filled, a 5mm fillet weld is made on the main reinforcement side. The whole is preheated to 100-120℃ before welding. Step (8) Flame calibration: Use a flame spray gun to bake the deformed position until the deformation is corrected to within the tolerance range.

[0006] Step (9) Spray paint: Spray paint on the push rod according to the process requirements.

[0007] The defects of the above process are as follows: (1) Flame cutting has poor cutting accuracy, low material utilization rate, and large cutting deformation, which requires a flat plate machine for leveling, affecting production efficiency; (2) There is a groove weld between the cover plate and the main reinforcement. The cover plate needs to be cut into grooves, which takes a long process and has low overall production efficiency. At the same time, the root space of the groove weld is narrow, which is not conducive to welding and is prone to non-fusion defects; (3) When assembling the cover plate, it needs to sink to the middle of the main reinforcement plate, and ensure that the distance between the upper surface of the cover plate and the upper end surface of the main reinforcement is not less than 5mm, which makes assembly difficult; (4) The cold crack sensitivity of Q890 grade steel plates with medium carbon content using offline quenching and tempering process is high, cold cracks are prone to occur during welding, and a higher preheating temperature is required; (5) There are two welds between the main reinforcement and the cover plate. After welding one weld, the other weld is welded, which is prone to deformation. The tempering temperature of the steel plate is low, and flame correction will reduce the local strength; (6) The welding wire used for positioning welding for primary and secondary assembly is ER50-6. If the strength is too low, it will affect the reliability of the overall welding strength of the workpiece.

[0008] In order to solve the above problems, people have been seeking an ideal technical solution. Summary of the invention

[0009] The purpose of the present invention is to address the deficiencies of the prior art and thereby provide a hydraulic support push rod welding method for a Q890 grade steel plate with low cold crack sensitivity, which has high steel utilization rate and high production efficiency.

[0010] In order to achieve the above-mentioned object, the technical scheme adopted by the present invention is: a hydraulic support push rod welding method of Q890 grade steel plate with low cold crack sensitivity, comprising Q890 grade steel plate with low carbon content and low cold crack sensitivity, the steel plate is produced by online quenching, thermomechanical rolling and tempering process, the cold crack sensitivity index Pcm of the steel plate is ≤0.23%, the carbon content is ≤0.10%, and the tempering temperature is above 480°C; Processed through the following steps: Step 1. Cutting: Arrange the materials on the surface of the steel plate, with the long sides of two adjacent parts close together without leaving any gaps, and use the common edge method to cut; use laser cutting method to cut; the laser cutting path is: The starting point of the first cutting path is located at a corner of the non-common side, and the end point of the first cutting path coincides with the starting point; the starting point of the cutting path of other parts is at the same angle as the starting point of the first cutting path, and the end point of the cutting path is located at the other end of the common side where the cutting starting point is located; Step 2. One-time assembly: Draw the parts position map on the base plate, use the tooling to put the parts in place, and then perform positioning welding; Step 3. Primary welding: Preheat the push rod as a whole to 50-80℃. After preheating, place the push rod with the bottom facing up on the robot welding platform. The robot welding platform will perform base, filling and cover welding on the push rod in sequence. After the fillet weld is filled, turn it over immediately and weld the internal fillet weld symmetrically. Step 4. Secondary assembly: Place the cover plate on the push rod part after one welding, adjust the part position, ensure that the end of the cover plate is flush with the end of the push rod body, and that fillet welds are formed between the two sides of the cover plate and the main reinforcement, and that the size deviation is within the set range. Mark the tack welding positions on both sides of the cover plate, and perform manual tack welding to ensure that the assembly gap is less than 1mm; Step 5. Secondary welding: Before welding, preheat the push rod to 50-80℃. After preheating, place the push rod with the top facing upward on the robot welding platform. Perform base, filler and cover welding on the fillet weld of the push rod in sequence. After the fillet weld is filled, stack and slowly cool. Step 6) Flame Calibration Use a flame spray gun to bake the deformed position until the deformation is corrected to within the tolerance range.

[0011] Based on the above, in step 1, laser cutting is performed by a laser cutting machine, and the laser cutting parameters are: laser power 12kw, cutting speed 1.2m / min, laser focal length +15mm, cutting gas is oxygen, gas pressure 0.45bar, and cutting height 0.3mm.

[0012] Based on the above, in step 2, the parts assembled on the bottom plate include the main ribs and the rib plates, the tack welding is performed manually, and the tack welding positions are marked before welding to ensure that the assembly gap is less than 1 mm.

[0013] Based on the above, in step 2, the same position is selected for the positioning welding of the outer and inner sides of the weld between the main reinforcement and the bottom plate.

[0014] Based on the above, in step 2, the parameters of manual positioning welding include: using ER62-G φ1.4mm welding wire, welding current 260-280A, voltage 30-32V, welding speed 350-400mm / min, the positioning welding of the main reinforcement and the bottom plate and cover plate is symmetrically distributed on both sides, each section of positioning welding is 200-300mm long, 400-500mm apart, and 4-5mm high.

[0015] Based on the above, in step 3, the weld leg size of the internal fillet weld welded once is 16-18 mm.

[0016] Based on the above, in step 3, the parameters of the primary welding include: using Ar + 20% CO 2 Mixed gas shielded welding, ER96-G φ1.6mm diameter solid wire. Bottom welding parameters: welding current 320-360A, voltage 27-39V, welding speed 40-45cm / min, shielding gas flow 15-20L / min. Filling and capping welding parameters: welding current 380-420A, voltage 29-31V, wire feeding speed 7-8m / min, welding speed 40-50cm / min, lateral sinusoidal swing of wire end 1-4mm, wire dry extension 20-25mm, shielding gas flow 20-25L / min, the robot's welding gun is at an angle of 45°±2° to the main rib plate.

[0017] Based on the above, in step 4, the size deviation of the fillet welds formed between the cover plate and the main reinforcement on both sides during the secondary assembly does not exceed 1.5 mm, and the parameters of the manual tack welding in this step are consistent with the tack welding parameters during the primary assembly.

[0018] Based on the above, in step 5, the parameters of the secondary welding are consistent with the parameters of the primary welding.

[0019] Based on the above, the method further comprises step 7: painting, spraying paint on the push rod according to the process requirements.

[0020] The present invention has outstanding substantive features and significant progress compared to the prior art. Specifically, the present invention has the following advantages: (1) Improved the efficiency of push rod parts cutting and sheet material utilization. The flame cutting was optimized to laser cutting, and the cutting speed was increased from 0.3m / min to 1.2m / min. At the same time, the parts were cut on the same edge to avoid the generation of waste between parts. (2) The production process of push rods is shortened. The application of laser cutting machine reduces the heat input of steel plate cutting, avoids the problem of heat deformation of flame-cut parts, and eliminates the leveling process of over-long parts; (3) The preheating temperature of the Q890 push rod before welding was reduced. The preheating temperature was reduced from 100-120℃ to 60-80℃. The cold crack sensitivity coefficient Pcm of the online quenched Q890 steel plate was ≤0.23%, the C content was ≤0.10%, and the cold crack tendency was not obvious. At the same time, the back weld of the above welding method had a preheating effect on the internal weld, and the internal weld had a post-heating effect on the back weld, avoiding the occurrence of cold cracks; (4) Avoids the decrease in push rod strength caused by flame correction. The tempering temperature of Q890 grade steel plate in the online quenching process is high, and the welding deformation is small when using symmetrical welding, which reduces the action time of flame correction.

[0021] (5) Reduced assembly difficulty and improved assembly efficiency. The groove weld between the cover plate and the main reinforcement is optimized to a fillet weld. The cover plate does not need to be sunk between the main reinforcements, but can be directly covered on top of the main reinforcement plate, making it easier to adjust the assembly size. (6) The welding wire used for primary and secondary assembly is ER62-G φ1.4mm. By matching appropriate welding parameters, not only the welding strength of the positioning weld is guaranteed, but also the occurrence of welding cold cracks during positioning welding is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the hydraulic support push rod in the present invention.

[0023] Figure 2 It is a schematic diagram of the weld of the hydraulic support push rod in the present invention.

[0024] Figure 3 It is a schematic diagram of the arrangement of the fillet welds at various locations of the hydraulic support push rod in the present invention.

[0025] Figure 4 It is a schematic diagram of the welding gun angle of the hydraulic support push rod in the present invention.

[0026] Figure 5 It is a schematic diagram of symmetrical welding of the positioning welding of the hydraulic support push rod in the present invention.

[0027] Figure 6 It is a schematic diagram of the positioning welding distribution of the hydraulic support push rod in the present invention.

[0028] Figure 7 It is a schematic diagram of the common edge cutting of the steel plate in the present invention.

[0029] In the figure: 1. Bottom plate; 2. Main reinforcement plate; 3. Cover plate. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0031] like Figure 1-Figure 7 As shown, a hydraulic support push rod welding method for Q890 grade steel plate with low cold crack sensitivity. The steel plate material selected in this embodiment is different from the traditional material. The steel plate adopts Q890 grade steel plate with low carbon content and low cold crack sensitivity. It is produced by online quenching (thermomechanical rolling) + tempering. The cold crack sensitivity index Pcm of the steel plate is ≤0.23%, the carbon content is ≤0.10%, and the tempering temperature is above 480°C.

[0032] Improve the process flow, reduce the number of groove processing steps, reduce the difficulty of assembly, and reduce the difficulty of welding, including: cutting → primary assembly → primary welding → secondary assembly → secondary welding → flame correction → painting Step (1) Cutting: Use a laser cutting machine to cut according to the drawing. After cutting, turn out the parts and use a grinder to grind the welds on each part to reveal the metallic luster. Key points: The steel plate is cut in the common edge cutting mode. When laying out the material, the long sides of the two parts are close together without any gaps, and they have a common long side. When planning the path, the cutting path of the first piece is the complete part outline, and the starting point is selected at a corner of the non-common edge side. The starting point and the end point coincide with each other. The starting point selection method for subsequent parts is the same as the first piece, but the end point is located at the other end of the common edge where the starting point is located. Laser cutting parameters: laser power 12kw, cutting speed 1.2m / min, laser focal length +15mm, cutting gas is oxygen, gas pressure 0.45bar, cutting height 0.3mm.

[0033] Step (2) One-time assembly: Draw position lines for main reinforcement, rib plates and other parts on the base plate, use tooling to place the main reinforcement and rib plates on the base plate, adjust the positions of various parts, mark the tacking positions, and perform tacking welding manually to ensure that the assembly gap is less than 1mm.

[0034] In this embodiment, as shown in the figure, only the bottom plate 1 and the main rib plate 2 are included. The outer and inner tack welds of the weld between the main rib and the bottom plate are selected at the same position, and ER62-G φ1.4mm welding wire is used. The welding current is 260-280A, the voltage is 30-32V, and the welding speed is 350-400mm / min. The tack welds of the main rib and the bottom plate and the cover plate are symmetrically distributed on both sides. The length of each tack weld is 200-300mm, the interval is 400-500mm, and the height is 4-5mm.

[0035] After assembly is completed, the welds formed between the main reinforcement plate and the bottom plate are all fillet welds.

[0036] Step (3) Primary welding: Before welding, preheat the push rod as a whole to 50-80℃. After preheating, immediately place the push rod with the bottom facing up on the robot welding platform. Two welding robots simultaneously perform base, filling, and cover welding on the push rod welds in sequence. Fill the fillet welds. After welding, turn the surface over immediately and weld the internal fillet welds symmetrically. The weld leg size is 16-18mm. The above welding uses Ar+20%CO2 mixed gas shielded welding and ER96-G φ1.6mm diameter solid wire. Base welding parameters: welding current 320-360A, voltage 27-39V, welding speed 40-45cm / min, shielding gas flow 15-20L / min. Filling and cap welding parameters: welding current 380-420A, voltage 29-31V, wire feeding speed 7-8m / min, welding speed 40-50cm / min, lateral sinusoidal oscillation of the end of the welding wire 1-4mm, welding wire dry extension 20-25mm, shielding gas flow 20-25L / min, the robot's welding gun is at an angle of 45°±2° to the main rib plate.

[0037] Step (4) Secondary assembly: Place the cover plate on the push rod part after welding, adjust the part position, ensure that the end of the cover plate is flush with the end of the push rod body, and the size deviation of the fillet weld formed by the two sides of the cover plate and the main reinforcement does not exceed 1.5mm. Mark the tack welding position on both sides of the cover plate, and perform tack welding manually to ensure that the assembly gap is less than 1mm. The tack welding wire, parameters and distribution form are consistent with the first assembly; In this step, compared with the traditional solution, the step of processing the slope is eliminated, so that a corner weld is formed between the cover plate and the main rib plate.

[0038] Step (5) Secondary welding: Before welding, preheat the push rod as a whole to 50-80℃. After preheating, immediately place the push rod with the top facing upward on the robot welding platform. Two welding robots simultaneously perform base, filler, and cover welding on the push rod in a symmetrical manner, fill the fillet weld, and stack and cool slowly after welding. The welding parameters are the same as the first welding. The symmetrical welding method on both sides, combined with the special characteristics of the material, can reduce the overall deformation problem caused by the welding process, and the deformation amount is greatly reduced.

[0039] Step (6) Flame calibration: Use a flame spray gun to bake the deformed position until the deformation is corrected to within the tolerance range.

[0040] Step (7) Spray paint Spray paint on the push rod according to the process requirements.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity, characterized in that: Including low carbon content Q890 grade steel plates with low cold crack sensitivity, the steel plates are produced by online quenching, thermomechanical rolling and tempering processes, the cold crack sensitivity index Pcm of the steel plates is ≤ 0.23%, the carbon content is ≤ 0.10%, and the tempering temperature is above 480℃; Processed through the following steps: Step 1. Cutting: Arrange the materials on the surface of the steel plate, with the long sides of two adjacent parts close together without leaving any gaps, and use the common edge method to cut; use laser cutting method to cut; the laser cutting path is: The starting point of the first cutting path is located at a corner of the non-common side, and the end point of the first cutting path coincides with the starting point; the starting point of the cutting path of other parts is at the same angle as the starting point of the first cutting path, and the end point of the cutting path is located at the other end of the common side where the cutting starting point is located; Step 2. One-time assembly: Draw the parts position diagram on the bottom plate, use the tooling to put the parts in place, and then perform positioning welding. The same position is selected for the positioning welding on the outside and inside of the weld between the main reinforcement and the bottom plate; Step 3. Primary welding: Preheat the push rod as a whole to 50-80℃. After preheating, place the push rod with the bottom facing up on the robot welding platform. The robot welding platform will perform base, filling and cover welding on the push rod in sequence. After the fillet weld is filled, turn it over immediately and weld the internal fillet weld symmetrically. Step 4. Secondary assembly: Place the cover plate on the push rod part after one welding, adjust the part position, ensure that the end of the cover plate is flush with the end of the push rod body, and that fillet welds are formed between the two sides of the cover plate and the main reinforcement, and that the size deviation is within the set range. Mark the tack welding positions on both sides of the cover plate, and perform manual tack welding to ensure that the assembly gap is less than 1mm; Step 5. Secondary welding: Before welding, preheat the push rod to 50-80℃. After preheating, place the push rod with the top facing upward on the robot welding platform. Perform base, filler and cover welding on the fillet weld of the push rod in sequence. After the fillet weld is filled, stack and slowly cool. Step 6) Flame Calibration Use a flame spray gun to bake the deformed position until the deformation is corrected to within the tolerance range.

2. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 1 is characterized in that: In step 1, laser cutting is performed using a laser cutting machine, and the laser cutting parameters are: laser power 12 kW, cutting speed 1.2 m / min, laser focal length +15 mm, cutting gas is oxygen, gas pressure 0.45 bar, and cutting height 0.3 mm.

3. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 2 is characterized in that: In step 2, the parts assembled on the base plate include the main ribs and rib plates. Positioning welding is performed manually, and the positioning welding positions are marked before welding to ensure that the assembly gap is less than 1 mm.

4. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 3 is characterized in that: In step 2, the parameters of manual tack welding include: using ER62-G φ1.4mm welding wire, welding current 260-280A, voltage 30-32V, welding speed 350-400mm / min, the tack welding of the main reinforcement and the bottom plate and cover plate is symmetrically distributed on both sides, each tack welding section is 200-300mm long, 400-500mm apart, and 4-5mm high.

5. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 4 is characterized in that: In step 3, the leg size of the internal fillet weld welded once is 16-18 mm.

6. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 5, characterized in that: In step 3, the parameters of the primary welding include: mixed gas shielded welding of Ar+20%CO2, solid core welding wire of ER96-G φ1.6mm diameter; bottom welding parameters: welding current 320-360A, voltage 27-39V, welding speed 40-45cm / min, shielding gas flow rate 15-20L / min; filling and cap welding parameters: welding current 380-420A, voltage 29-31V, wire feeding speed 7-8m / min, welding speed 40-50cm / min, lateral sinusoidal swing of the end of the welding wire 1-4mm, welding wire dry extension 20-25mm, shielding gas flow rate 20-25L / min, the robot's welding gun is at an angle of 45°±2° to the main reinforcement plate.

7. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 6, characterized in that: In step 4, the size deviation of the fillet welds formed between the two sides of the cover plate and the main reinforcement during the secondary assembly does not exceed 1.5 mm. The parameters of the manual positioning welding in this step are consistent with the positioning welding parameters during the primary assembly.

8. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 7, characterized in that: In step 5, the parameters of the secondary welding are consistent with those of the primary welding.

9. The method for welding a hydraulic support push rod of a Q890 grade steel plate with low cold crack sensitivity according to claim 8, characterized in that: The process also includes step 7: painting, spraying paint on the push rod according to the process requirements.

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