A square and rectangular tube forming system with hot and cold composite forming and thickened corners

Abstract

The invention discloses a hot and cold composite forming system for square and rectangular tubes with thickened corners. The system includes a feeding device, a roller introduction unit, a local induction heating device, a fine forming unit, a water cooling device, an air cooling zone and a cutting device connected in sequence; the fine forming unit includes: a frame and four rollers; the four rollers are arranged in the frame and distributed at the four corners of the square and rectangular tube, and each roller is provided with a roller movement control knob to control the roller to move in the horizontal, longitudinal and forming directions at the same time; the frame is provided with a frame rotation control button to control the frame rotation; the fine forming unit is provided with a temperature measuring instrument and an automatic feedback device. The invention can not only reduce the forming force of the material and improve the forming performance of the material; it can also eliminate the residual stress caused by work hardening and the cracking phenomenon that may be caused, and the obtained square and rectangular tube corner contour is dense, the inner and outer corner radius is very small, the corner angle is close to 90°, and is accompanied by the thickening of the corner.

Description

Technical Field

[0001] The invention relates to the technical field of metal material forming equipment, and more particularly to a cold-hot composite forming square and rectangular tube forming system with thickened corners. Background Art

[0002] Steel structure materials are praised as one of the "green buildings" of the 21st century, and square rectangular steel tubes are the best column materials in steel structures. Traditional cold-formed square tubes have large residual stress at their corners due to the secondary processing hardening effect of the cold-forming process, which directly leads to a decrease in their ductility and may cause cracking during use, greatly limiting the scope of use of square tubes. Generally, they cannot be used as the main material in high-rise buildings. The square tubes used in high-rise buildings are now made of 4 steel plates welded together, which has great limitations; at the same time, the corner radius of the cold-formed square tube is large, and the welding performance is very poor. It is necessary to use methods such as corner material addition to improve its welding performance, but this will increase the manufacturing cost.

[0003] The square tubes produced by traditional cold-bent square tube forming equipment have poor corner performance, residual stress exists at the corners, and the elongation is reduced, which makes them prone to breakage. Summary of the invention

[0004] In order to solve the defects of the traditional cold-bent square tube corners, the present invention proposes a cold-hot composite forming square and rectangular tube forming system with thickened corners. The hot forming technology, namely the local induction heating technology, is introduced into the traditional roll bending forming process. High temperature can not only reduce the forming force of the material and improve the forming performance of the material; at the same time, it can eliminate the residual stress caused by work hardening and the possible cracking phenomenon. In addition, the square tube corners formed by cold-hot composite forming have a dense contour, a small inner and outer corner radius, a corner angle close to 90°, and are accompanied by thickening of the corners.

[0005] The purpose of the invention is to provide a cold-hot composite forming square and rectangular tube forming system with thickened corners.

[0006] include:

[0007] The feeding device, roller introduction unit, local induction heating device, finishing forming unit, water cooling device, air cooling zone and cutting device are connected in sequence;

[0008] The fine forming unit includes: a frame and four rollers;

[0009] Four rollers are set in the frame and distributed at the four corners of the square rectangular tube. Each roller is equipped with a roller movement control knob to control the roller to move in the horizontal, longitudinal and forming directions at the same time.

[0010] The rack is provided with a rack rotation control button to control the rack rotation;

[0011] The precision forming unit is equipped with a temperature measuring instrument and an automatic feedback device.

[0012] Among them, preferred:

[0013] The local induction heating device is provided with an induction coil, and the induction coil is wrapped with a layer of silicon steel sheet at the four corners corresponding to the square rectangular tube to heat the four corners of the square rectangular tube.

[0014] The number of the fine forming units is N, where N is an odd number greater than 1; a heat preservation device is arranged between two fine forming units. The fine forming units of the odd number are fixed; the fine forming units of the even number can rotate. The units rotate clockwise or counterclockwise around the axis of the forming system.

[0015] Taking into account the cost and effect, the optimal number of precision forming units is five;

[0016] The 1st, 3rd and 5th fine forming machine units are fixed; the 2nd and 4th fine forming machine units can be rotated, and can rotate clockwise or counterclockwise with the axis of the forming system as the axis.

[0017] The rotation angles of the 2nd and 4th finishing forming units are both 0-3°.

[0018] The 2nd and 4th finishing forming units are rotated by a worm gear device.

[0019] The roller diameter difference between each two adjacent finishing forming units is 1 to 5 mm.

[0020] The heat preservation device is a flame spray gun heat preservation device

[0021] The present invention can specifically adopt the following technical solutions:

[0022] include:

[0023] 1. Loading device: Load the pre-finished square and rectangular steel pipes into the production system;

[0024] 2. Two roller-pressing introduction units: After two passes of the roller-pressing introduction system, the square and rectangular tubes are smoothly and symmetrically introduced into the subsequent production system.

[0025] 3. Local induction heating device: In this system, a layer of silicon steel sheet is wrapped around the four corners of the square tube corresponding to the induction coil. The magnetic driving and magnetic conductivity of the silicon steel sheet is used to guide the local distribution of the electromagnetic wire, thereby realizing local heating of the four corners of the square tube with a large fillet radius. At the same time, the temperature meter and automatic feedback system are used to ensure the accuracy and stability of the heating temperature. The heating temperature range is: 750℃~1100℃, and the heating time is determined according to the type of steel and the heating frequency.

[0026] 4. Finishing forming unit: 5 finishing forming units together form a hot finishing and straightening process. The temperature of the finishing stage is controlled between 700-950℃. After each finishing forming unit, the deformation degree of the cross-sectional area of ​​the square rectangular tube is in the range of 0-5%. There are 5 passes of finishing forming units, among which the 1st, 3rd and 5th units are fixed, and the 2nd and 4th units can rotate through the worm gear device. The 2nd and 4th units can twist the square rectangular tube in opposite directions with an angle of 0-3° to ensure the straightness of the square rectangular tube. At the same time, the speeds of the 5 finishing forming units are different. The speed of the frame in the latter pass will be faster than that of the previous one. Therefore, tension will be generated between each pass. Under the joint action of tension and the 2nd and 4th units, the square rectangular tube can realize the shaping and straightening functions, eliminating the redundant deformations such as twisting and warping generated during the hot finishing process. )

[0027] 5. Thermometer and automatic feedback system

[0028] Each precision forming rack is equipped with a temperature measuring instrument and an automatic feedback system to detect and feedback the temperature of the formed square tube to ensure the constant temperature of the square tube during the heating process.

[0029] 6. Four flame spray gun insulation systems

[0030] In the precision forming unit, one is set between every two adjacent racks to ensure the constant temperature of the pipe, and the temperature is controlled at 700-950℃.

[0031] 7. Water cooling device

[0032] The square tube is cooled by the water cooling system to ensure the strength of the finished square tube. The final cooling temperature is set at around 350℃, and the cooling speed is controlled according to different steel grades and performance requirements.

[0033] 8. Air cooling area

[0034] The water-cooled square tube will gradually cool down with the room temperature.

[0035] 9. Cutting device

[0036] The finished square and rectangular tubes are cut horizontally and cut according to the actual required length.

[0037] The present invention is a cold-hot composite forming system for square and rectangular tubes with thickened corners, which combines the advantages of roll forming and hot forming. It mainly solves the problems of thinning corners, large radius and residual stress of cold-bent square and rectangular tubes. Through the process research of rectangular tubes with thickened corners, it explains the feasibility of hot roll bending process for rectangular tubes with thickened corners.

[0038] The hot and cold composite forming system for square and rectangular tubes with thickened corners of the present invention belongs to the field of local heating roll bending forming equipment, and is used to solve the problem of thinning corners of square and rectangular tubes during cold bending forming. The square and rectangular tubes involved in the forming are waterless, and the device itself belongs to a secondary forming device. The introduction unit is provided with at least 2-pass racks in sequence, so that the once-formed square and rectangular tubes can enter the subsequent equipment smoothly and symmetrically. Induction heating uses a specific heating coil to heat it. The secondary fine forming unit includes 5 passes, which play a role in shaping and straightening. At the same time, a flame spray gun insulation device is inserted to prevent the temperature of the square and rectangular tubes from decreasing. Finally, a water cooling device is used to quench the formed square and rectangular tubes to ensure the strength performance of the finished product.

[0039] After the rectangular tube heated by induction in the present invention reaches a certain temperature, the plastic properties of the four fillet parts are improved, while the strength of other parent materials is not affected. Entering the finishing process, under the effect of four-way extrusion stress and the skin effect of induction heating, the metal on the outer side of the square tube is blocked from flowing inward, forcing it to flow to the outer corner area of ​​the square tube, achieving thickening of the corners, reducing the fillet radius, and achieving product dimensional accuracy.

[0040] In the local induction heating system of the present invention, the self-made induction heating system of the present invention can achieve uniform and accurate simultaneous heating of the four corners of the rectangular tube while avoiding the plane area of ​​the parent material. An automatic feedback temperature adjustment system is also configured, which captures the temperature before forming through a temperature measuring instrument and feeds it back to the induction heating system. If the measured temperature is within the forming temperature range, the current power is maintained; if not, the power is quickly increased or decreased to adjust the appropriate forming temperature, thereby ensuring the constant heating temperature.

[0041] The roller mill of the precision forming unit of the prior art rolls the plate planes of the four sides of the square tube, and the rollers cannot move. Therefore, the rollers need to be as large as the side length of the square tube to be produced, which greatly limits the production of large-size square tubes, and a set of equipment can only produce products of one specification. The rollers of the precision forming unit of the present invention are distributed at the four corners of the square tube, and the four outer corners of the square tube are directly roll-formed, and the rollers at the four corners can move in the horizontal, longitudinal and forming directions (oblique) at the same time to adapt to the forming of square tubes of different sizes. Therefore, the size range of the square tubes prepared by the system of the present invention is greatly improved compared with the prior art, and a square rectangular steel tube with a circumference of 80mm-9600mm and a wall thickness of 6mm-80mm can be produced at most. In addition, the present invention rolls the corners of the square tube, and there is no need to replace the rollers. Products of all specifications can be produced with a set of equipment, which greatly reduces the production cost.

[0042] The present invention preferably uses 5 precision forming units, wherein the 1st, 3rd and 5th precision forming units are fixed to ensure the stability of the traveling direction and the forming direction of the square tube during the forming process, wherein the 2nd and 4th units can be rotated, and the redundant deformations such as twisting and warping occurring during the forming process can be immediately straightened and corrected, various defects can be eliminated, and the appearance accuracy and performance quality of the obtained square tube products can be greatly improved. At the same time, because there are 5 precision forming units in total, the corner shape of the square tube can be changed to a greater extent, making it closer to a right angle, and the corner wall thickness increases more significantly, which improves the cross-sectional performance of the square tube, and the mechanical properties and welding properties become better, and the wall thickness size range of the square tube that can be produced also becomes larger.

[0043] Except for the first precision forming unit, each subsequent precision forming unit is equipped with a heat preservation device in front to ensure the constant temperature of the square tube during the entire precision forming process. The forming temperature of the square tube is constant, deformation is easier, the corners of the square tube can be capable of and easier to become right angles, and the increase in corner wall thickness also becomes a natural result. The size of the square tube that can be produced also becomes larger, and the performance conditions of the obtained square tube will be better.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] (1) Compared with traditional roll forming equipment, a hot-cold composite forming system for square and rectangular tubes with thickened corners adds induction heating equipment and insulation equipment. The secondary forming process is carried out under high temperature conditions, which greatly improves the corner performance of the square and rectangular tubes, reduces residual stress, and prevents work hardening. While ensuring the strength of the raw materials, it has little effect on the parent material. At the same time, the forming process reduces the wear of the equipment. The addition of a water cooling device can ensure the mechanical properties of the square and rectangular tubes.

[0046] (2) This device covers the production of all types of steel, and the production scale range is wide, with a circumference of 80mm-9600mm and a wall thickness of 6mm-80mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic diagram of a corner thickened rectangular tube forming system provided by the present invention;

[0048] Figure 2 A schematic diagram of the rotation of the precision forming unit of the present invention;

[0049] Figure 3 A schematic structural diagram of a precision forming unit according to the present invention;

[0050] Figure 4 A schematic diagram of roller pressing of a precision forming unit in the prior art;

[0051] Figure 5A schematic diagram of rolling of the precision forming unit of the present invention;

[0052] Figure 6 Schematic diagram of the local induction heating device of the present invention.

[0053] Description of reference numerals:

[0054] 1. Feeding device; 2. Roller introduction unit; 3. Local induction heating device; 4. Precision forming unit; 5. Temperature measuring instrument and automatic feedback system; 6. Flame spray gun insulation device; 7. Water cooling device; 8. Air cooling area; 9. Cutting device; 11. Preformed square tube; 12. Roller movement control knob; 13. Roller; 14. Frame rotation control knob; 15 Silicon steel sheet; 16 Induction heating coil. DETAILED DESCRIPTION

[0055] Example

[0056] A hot and cold composite forming square and rectangular tube forming system with thickened corners, comprising: a feeding device 1, a roller pressure introduction unit 2, a local induction heating device 3, a fine forming unit 4, a water cooling device 7, an air cooling zone 8 and a cutting device 9 connected in sequence;

[0057] The finishing forming unit 4 comprises: a frame and four rollers 13;

[0058] Four rollers 13 are arranged in the frame and distributed at the four corners of the square rectangular tube. Each roller is provided with a roller movement control knob 12 to control the roller to move in the horizontal, longitudinal and forming directions at the same time.

[0059] A rack rotation control button 14 is provided on the rack to control the rotation of the rack;

[0060] The finishing forming unit 4 is provided with a temperature measuring instrument and an automatic feedback device 5 .

[0061] The local induction heating device 2 is provided with an induction coil 16, and the induction coil is wrapped with a layer of silicon steel sheet 15 at the four corners corresponding to the square rectangular tube to heat the four corners of the square rectangular tube.

[0062] There are five finishing forming units, and a heat preservation device is arranged between two finishing forming units. The first, third, and fifth finishing forming units are fixed; the second and fourth finishing forming units can be rotated. During the hot finishing roller rolling process of this embodiment, the square tube does not have defects such as distortion, so the rotation angles of the second and fourth finishing forming units are both 0°. The heat preservation device is a flame spray gun heat preservation device 6.

[0063] Molding methods include:

[0064] (1) The Q235 steel plate is pre-bent into a preformed square tube with an outer corner radius of R = 20.0 mm and a size of 200*200 mm, wherein the wall thickness of the flat area is 8.0 mm and the wall thickness of the corner is 7.8 mm.

[0065] (2) The preformed square tube is sent into a local induction heating device through a guide roller, the heating temperature is 1050°C, and the heating time is 15 seconds;

[0066] (3) After that, the steel sheet is formed by five finishing forming machines. The temperature of the flame spray gun insulation system between every two forming machines is 950°C, the roller diameter difference between every two adjacent finishing forming machines is 3mm, and the deformation degree of each finishing forming machine is about 3%.

[0067] (4) After hot finishing, a rectangular tube with a size of 193*193mm, a wall thickness of 8mm in the flat area, a wall thickness of 8.8mm in the corners, and an outer corner radius of 2mm was obtained. After quality inspection, the residual stress of the hot and cold composite formed square tube was eliminated, the work hardening was eliminated, and the plasticity was enhanced.

Claims

1. A hot and cold composite forming system for square and rectangular tubes with thickened corners, characterized in that: The system comprises a feeding device, a roller-pressing introduction unit, a local induction heating device, a finishing forming unit, a water cooling device, an air cooling zone and a cutting device connected in sequence; The fine forming unit includes: a frame and four rollers; Four rollers are set in the frame and distributed at the four corners of the square rectangular tube. Each roller is equipped with a roller movement control knob to control the roller to move in the horizontal, longitudinal and forming directions at the same time. The rack is provided with a rack rotation control button to control the rack rotation; The precision forming unit is equipped with a temperature measuring instrument and an automatic feedback device; The local induction heating device is provided with an induction coil, and the induction coil is wrapped with a layer of silicon steel sheet at the four corners corresponding to the square rectangular tube to heat the four corners of the square rectangular tube.

2. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 1, characterized in that: The number of the precision forming units is N, where N is an odd number greater than 1; a heat preservation device is provided between two precision forming units; The odd-numbered precision forming machine units are fixed; the even-numbered precision forming machine units are rotatable.

3. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 2, characterized in that: The number of the precision forming units is five.

4. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 3, characterized in that: The 1st, 3rd and 5th finishing forming units are fixed; the 2nd and 4th finishing forming units can be rotated.

5. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 4, characterized in that: The rotation angles of the 2nd and 4th finishing forming units are both 0-3°.

6. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 4, characterized in that: The 2nd and 4th finishing forming units are rotated by a worm gear device.

7. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 2, characterized in that: The roller diameter difference between each two adjacent finishing forming units is 1~5mm.

8. The hot and cold composite forming square and rectangular tube forming system with thickened corners as claimed in claim 2, characterized in that: The heat preservation device is a flame spray gun heat preservation device.

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