CN114619203B - Forming method of large-diameter stainless steel pipe - Google Patents
Forming method of large-diameter stainless steel pipe Download PDFInfo
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- CN114619203B CN114619203B CN202111599513.5A CN202111599513A CN114619203B CN 114619203 B CN114619203 B CN 114619203B CN 202111599513 A CN202111599513 A CN 202111599513A CN 114619203 B CN114619203 B CN 114619203B
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- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
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- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
Abstract
The invention discloses a method for forming a large-caliber stainless steel pipe, which comprises the steps of firstly, splitting a stainless steel plate into required rectangular plates; then the rectangular plate is placed on the lower pressing piece, the press drives the upper pressing piece to move downwards through the pressing rod, and the edges of two sides of the rectangular plate are respectively formedThe arc bending with radius r, the central angle corresponding to the single-side bending part is beta, the width of the compression bar is B,
r is more than or equal to 0.8 pi D/(2 pi-pi beta/180) and less than or equal to pi D/(2 pi-pi beta/180); then, an upper pressing piece and a lower pressing piece are used for enabling the middle straight part of the rectangular plate to form an arc-shaped bend, so that the rectangular plate is formed into a cylindrical material with an opening; extruding the outer side of the cylindrical material by using an extruding device to close the opening of the cylindrical material, and then welding the opening of the cylindrical material to form a tubular semi-finished product; and rounding and straightening the semi-finished product to form the stainless steel pipe. The invention can effectively avoid the interference generated during pipe coiling, is beneficial to improving the processing efficiency and reducing the manufacturing cost.
Description
Technical Field
The invention relates to the technical field of pipe processing, in particular to a forming method of a large-caliber stainless steel pipe.
Background
In the fields of petroleum pipeline transportation and the like, a large number of large-caliber stainless steel pipes are used, generally, the diameter of each stainless steel pipe is larger than 300mm, the length of each pipe is 3-4m, and the wall thickness of each stainless steel pipe is thick, so that stainless steel plates are usually rolled and bent by a pipe rolling device to form a semi-finished product with a splicing opening, then the opening is welded by laser welding, the stainless steel pipes are formed, and the qualified stainless steel pipe products are formed by processes of shaping, grinding welding seams and the like in the later period.
As shown in fig. 1 of the specification, in the prior art, a pipe coiling device generally includes two lower press rolls 1 and an upper press roll 2, specifically, a stainless steel rectangular plate is placed on the two lower press rolls, then the upper press roll is pressed downwards by a press (not shown in the figure) through a press rod 4, so that the rectangular plate is gradually formed into an arc-shaped bent semi-finished cylindrical material 31 with an opening from one side to the other side, and the cylindrical material openings are welded together by laser welding to form a large-diameter stainless steel pipe.
However, such a tube coiling device and a corresponding tube coiling method in the prior art have the following technical defects: firstly, the upper press roll and the lower press roll need to be extruded in the vertical direction through the press, and as the upper press roll and the lower press roll need to have lengths not less than the length of the pipe, namely, the lengths of the upper press roll and the lower press roll need to be more than or equal to 3-4m, and correspondingly, the upper press roll and the lower press roll need to simultaneously use more than 2 large-scale presses to realize the pipe coiling of the rectangular plate, on one hand, the manufacturing cost is increased, on the other hand, the multiple presses need to realize the complete synchronization of the actions, the technical difficulty is high, once the actions are asynchronous, the upper press roll is easy to generate bending deformation, and then the forming quality of the stainless steel pipe is directly influenced. Secondly, as shown in fig. 1, when a horizontal rectangular plate material is gradually pressed into a cylindrical material from a roll, the upper press roll is "enclosed" in the cylindrical material having an opening. It can be understood that the upper press roll is required to be provided with a bearing, a bracket and the like connected with the press rod at least at two ends, and because the centers of the bearing, the bracket and the like are arranged in a vertical plane passing through the axis of the upper press roll, when the rectangular plate is gradually bent into a cylindrical semi-finished product, one side edge of the rectangular plate can cross the vertical plane passing through the axis of the upper press roll, so that the rectangular plate is interfered with the press rod connecting the bearing and the bracket. The method is favorable for solving the problem of interference with a rectangular plate, but can cause the defect that the bearing and the support cannot be coplanar with the acting force of the pressure lever, so that the strength and the rigidity of the upper pressure roller, the bearing, the support, the pressure lever and the like are reduced.
Disclosure of Invention
The invention aims to solve the problems of high manufacturing cost, difficult quality guarantee, easy interference during pipe coiling and the like of the conventional forming method of the large-caliber stainless steel pipe, and provides the forming method of the large-caliber stainless steel pipe, which can effectively avoid the interference during pipe coiling, is beneficial to improving the processing efficiency and reducing the manufacturing cost.
In order to achieve the purpose, the invention adopts the following technical scheme:
a forming method of a large-caliber stainless steel pipe is suitable for manufacturing a stainless steel rectangular plate into a stainless steel pipe with the pipe diameter of D through an upper pressing piece and a lower pressing piece, and comprises the following steps:
a. the stainless steel plate is disassembled and cut into required rectangular plates, the length of each rectangular plate is equal to that of the stainless steel pipe, and the width of each rectangular plate is equal to the perimeter of the stainless steel pipe;
b. the rectangular plate is horizontally placed on a lower pressing piece arranged on a frame, a press drives the upper pressing piece to move downwards through a pressing rod, so that arc-shaped bends with the radius of r are formed on two side edges of the rectangular plate respectively, the central angle corresponding to the bent part on one side is beta, the width of the pressing rod is B, and
c. using an upper pressing piece and a lower pressing piece to enable the middle straight part of the rectangular plate to form arc-shaped bending with the same bending radius as the edges of the two sides, so that the rectangular plate is formed into a cylindrical material with an opening;
d. extruding the outer side of the cylindrical material by using an extruding device to close the opening of the cylindrical material, and then welding the opening of the cylindrical material to form a tubular semi-finished product;
e. and rounding and straightening the semi-finished product to form the stainless steel pipe.
The method comprises the steps of splitting a stainless steel plate into required rectangular plates, horizontally placing the rectangular plates on a lower pressing piece, downwards moving an upper pressing piece to press the rectangular plates, rolling the rectangular plates into cylindrical materials with openings, welding the openings of the cylindrical materials to form tubular semi-finished products, and then rounding, straightening and the like the semi-finished products to form the stainless steel tube. Of course, the finished stainless steel tube needs to be tested by corresponding pressure tests and the like. Since the above steps and methods are prior art, they will not be described in detail herein.
Different from the prior art, the invention firstly carries out extrusion pre-bending on two sides of a rectangular plate so as to enable the rectangular plate to form a U shape with two bent sides and straight middle, and then carries out extrusion bending on the straight middle part of the rectangular plate so as to form a cylindrical material with an opening. It can be understood that, when the rectangular plate is processed by pre-bending, the central angle of the bent two sides of the rectangular plate is smaller, so that the rectangular plate does not interfere with the pressing rod of the upper pressing piece. That is, the center of the pressing rod and the center of the upper pressing member may be located in the same vertical plane, thereby preventing the pressing rod or the upper pressing member from being subjected to an eccentric moment during pressing.
In addition, the invention changes the original press roll into a roller, so that the rectangular plate can be conveniently moved back and forth in the longitudinal direction through a corresponding driving mechanism, and the rectangular plate can be extruded and bent into a cylindrical plate with an opening through the roller by using one press. That is, the invention can roll and bend the stainless steel plate into the long stainless steel pipe with large caliber by one press, thereby being convenient to process and manufacture by the existing equipment and being beneficial to reducing the manufacturing cost.
In particular, the invention controls the central angle beta corresponding to the single-side bending part of the rectangular plate in the pre-bending process within the following range:
on one hand, interference between the pressing rod and the edge of the rectangular plate when the pressing piece extrudes the middle straight part of the rolled and bent rectangular plate can be avoided, and the pressing piece can be conveniently moved out from one end of the cylindrical plate when the rectangular plate is rolled and bent into the cylindrical plate with the opening. On the other hand, the gap between the edge of the cylindrical material and the pressure rod is reduced as much as possible, and the cylindrical material is conveniently extruded into an opening to be closed by the extruding device.
The central angle of the curved portion is represented by β degrees (360 ° degrees) instead of radian (2 pi radians).
Preferably, the frame is provided with a side positioning structure capable of driving the rectangular plate to move transversely and positioning, in the step b, the side positioning structure firstly enables the rectangular plate to deviate towards one side so as to enable one side edge of the rectangular plate to form arc bending with the radius r, the eccentric distance of the center line of the length direction of the rectangular plate relative to the longitudinal direction of the frame in the horizontal direction is a, then the rectangular plate deviates towards the other side so as to enable the other side edge of the rectangular plate to form arc bending with the radius r, and the a is more than or equal to 0.3 pi D and less than or equal to 0.4 pi D.
As mentioned above, the two side edges of the rectangular plate need to be bent into the arc-shaped bend with the radius r, and therefore, the side positioning structure of the invention firstly offsets the rectangular plate to one side by an eccentric distance a, so that the edge of one side of the rectangular plate can be extruded and pre-bent, and then the side positioning structure firstly offsets the rectangular plate to the other side by an eccentric distance a, so that the edge of the other side of the rectangular plate can be extruded and pre-bent.
In particular, the present invention controls the eccentricity a in the following range: a is more than or equal to 0.4 pi D and less than or equal to 0.5 pi D, so that the rectangular plate can be extruded and pre-bent from the edge of the outermost side, the flat part which is not extruded and bent is prevented from being left at the edge of the rectangular plate, and the phenomenon of 'air compression' of the upper pressing piece caused by overlarge eccentric distance is prevented.
Preferably, the lower pressing piece comprises a left row of lower roller groups and a right row of lower roller groups which are symmetrically arranged, the lower roller groups comprise a plurality of lower rollers which are longitudinally arranged, the upper pressing piece comprises an upper roller which is arranged at the lower end of the pressing rod and is positioned between the left row of lower roller groups and the right row of lower roller groups, the axial lines of the upper roller and the lower roller are vertical to the longitudinal direction of the rack, the circumferential surface of the upper roller is an outward convex arc-shaped ring surface with the radius equal to R, and D/2.2 is more than or equal to R and is less than or equal to D/2.1.
Because the lower pressing piece comprises the left and right rows of lower roller sets which are symmetrically arranged, when the rectangular plate is placed on the lower pressing piece and the upper pressing piece moves downwards to press the rectangular plate, the rectangular plate can move forwards and backwards in the longitudinal direction through the corresponding driving mechanism, and the rectangular plate is ensured to have smaller rolling friction resistance when moving forwards and backwards.
Particularly, the circumferential surface of the upper roller is an outer convex arc-shaped ring surface with the radius equal to R, and the radius R is controlled in the following range: d/2.2 is more than or equal to R and less than or equal to D/2.1, so that the rectangular plate can be finally rolled into arc bending with the radius R, and meanwhile, the phenomenon that the radius of the arc bending is too small is avoided, and the smooth arc bending is ensured.
Preferably, the rack is provided with a longitudinal driving mechanism, the width of the upper roller is S, and S is more than or equal to 1.2B and less than or equal to 1.3B, and the step B comprises the following steps:
b1. the upper roller moves downwards to enable the edge of one side end of the rectangular plate to be locally bent in an arc shape with the radius r, and then the rectangular plate is longitudinally moved by a longitudinal driving mechanism, so that a first arc-shaped bending belt with the radius r is formed at the edge of one side of the rectangular plate; b2. the side positioning structure enables the rectangular plate to be shifted to the other side S, and the step b1 is repeated, so that a second arc-shaped bending belt with the radius r is formed at one side edge of the rectangular plate;
b3. repeating the step b2 until an arc-shaped bend with the radius r is formed at one side edge of the rectangular plate;
b4. and repeating the steps b1-b3 until an arc-shaped bend with the radius r is formed at the other side edge of the rectangular plate.
According to the invention, the edge of one side end of the rectangular plate is locally bent into an arc with the radius r through the upper roller, then the rectangular plate is longitudinally moved by the longitudinal driving mechanism, so that the arc is bent to extend from one end of the rectangular plate to the other end, and then an arc bending belt with the radius r is formed at one side edge of the rectangular plate. That is, the upper pressing member presses the curled rectangular plate material step by step, so that the pressure required by the press can be remarkably reduced, the specification of the press can be reduced, and the manufacturing cost can be reduced.
In addition, the offset of the rectangular plate is equal to the width S of the upper roller, so that the continuity between adjacent arc-shaped bending belts on the rectangular plate can be ensured, and the smooth forming of arc-shaped bending with the radius r at the edge of the rectangular plate is facilitated.
In particular, the present invention controls the width S of the top roller in the following range: s is more than or equal to 1.2B and less than or equal to 1.3B, namely, the width of the upper roller is larger than that of the pressure rod, and on one hand, when the rectangular plate is bent into the cylindrical material, the upper roller can move out of one end of the cylindrical material. On the other hand, the upper roller in the step c can be extruded and bent from the middle of the straight part of the rectangular plate, so that the interference between the bending parts at two sides and the pressure rod can be avoided.
Preferably, the side positioning structure bagThe movable rack is characterized by comprising a plurality of movable rods which are arranged on the rack in a transversely movable manner, the movable rods are connected into an integral frame structure through connecting support rods, a power unit for driving the connecting support rods to move left and right is arranged on the rack, stop rods which extend upwards are respectively arranged at two ends of each movable rod, the distance between the lower ends of the stop rods is pi D, arc-shaped bent stop surfaces with central angles theta are formed inwards from the lower ends to the upper ends of the inner sides opposite to the stop rods, and the lower ends are connected with the movable rods
The radius of the stop surface is: a + pi D/2, in the step b1, horizontally placing a rectangular plate on the lower pressing piece, respectively abutting two sides of the rectangular plate against the lower end of the stop lever on one corresponding side, driving the moving rods on the left side and the right side to move to one side by the power unit through the connecting support rod, and then eccentrically positioning the rectangular plate on the rack; in step b2, the stop lever on the side away from the upper press member axis pushes the rectangular plate to shift S to the other side.
When a rectangular plate is placed on the lower pressing piece, the rectangular plate is supported on the lower roller sets which are symmetrically arranged in the left row and the right row, and the two sides of the rectangular plate abut against the stop levers on the corresponding side, so that the rectangular plate is positioned in the transverse direction. When the rectangular plate needs to be transversely moved so as to be eccentrically positioned on the rack, the rectangular plate can be conveniently and transversely eccentrically arranged only by driving the eccentric distance required by transverse movement of the lower pressing piece through the power unit.
Particularly, when the outermost side of the rectangular plate is extruded and bent to form a first arc-shaped bending belt, the edge of the other side of the rectangular plate can be tilted upwards, and the edge forms an arc-shaped track in the air. As can be seen from the calculation, the central angle corresponding to the arc-shaped track is approximately equal to
Accordingly, the arc-shaped locus corresponds to a radius substantially equal to a + π D/2. Therefore, the inner side of the stop lever is provided with the arc-shaped bending stop surface with the central angle equal to theta and the radius of a + pi D/2, thereby ensuring that the edge of the rectangular plate can be always limited by the stop lever when being tilted upwards,and then the rectangular plate is ensured to have stable eccentricity.
It can be understood that when one side of the rectangular plate is extruded and bent to form the second arc-shaped bending belt, the radius corresponding to the arc-shaped track formed by the edge of the other side is smaller than a + pi D/2, and the stop lever is driven by the power unit to move transversely, so that the edge of the rectangular plate can be ensured to be always positioned against the stop surface of the stop lever on one side.
Preferably, the extrusion device comprises extrusion roller groups positioned at two sides of the frame, each extrusion roller group comprises a plurality of extrusion rollers uniformly distributed along the longitudinal direction, the circumferential surface of each extrusion roller is an inwards concave arc-shaped ring surface with the radius equal to D/2, and the distance between the first extrusion roller and the last extrusion roller of the extrusion roller groups at two sides is gradually reduced from (D + B/pi) to D.
It can be known from the foregoing that the diameter of the cylindrical material with the opening is slightly larger than the pipe diameter D, and when we place the cylindrical material between the extrusion roller sets at the two sides of the frame, the extrusion roller sets at the two sides move relatively to extrude the outer side of the cylindrical material, so that the diameter of the cylindrical material is reduced, and the opening is closed, so as to weld the opening.
Particularly, the distance between the first extrusion roller and the last extrusion roller of the two-side extrusion roller set of the invention is gradually reduced from (D + B/pi) to D, namely, the distance between the last extrusion roller is just equal to the pipe diameter D, and the distance between the first extrusion roller is greater than the pipe diameter D + B/pi, so that the cylindrical material can be conveniently sent into the gap between the first pair of extrusion rollers, when the extrusion rollers rotate relatively, on one hand, the extrusion necking effect can be formed on the cylindrical material, and on the other hand, the cylindrical material can be driven to move forwards. After the cylindrical material is extruded and necked by the last pair of extrusion rollers, the cylindrical material with the diameter D can be formed, and the opening of the cylindrical material can be welded at the moment. That is, the cylindrical material may be welded while being squeezed and constricted.
Preferably, the lower end of the stop lever is slidably connected with the moving lever, a driving oil cylinder for driving the stop lever to slide is arranged on the moving lever, a limiting structure is further arranged between the moving lever and the stop lever, so that the stop lever can be positioned at the outermost position, when the stop levers at two sides are positioned at the outermost position, the distance between the lower ends of the stop levers at two sides is pi D, in step b1, the stop levers at two sides are positioned at the outermost position, then the rectangular plate is horizontally placed on the lower pressing piece, two sides of the rectangular plate respectively abut against the lower ends of the stop levers at one corresponding side, and when an arc bending belt with the radius of r is formed at one side edge of the rectangular plate, the edge of the rectangular plate upwarps along the stop surface of the stop lever at one corresponding side.
It can be understood that, when the inner side of the blocking rod is an arc-shaped blocking surface, the distance between the blocking rods on the two sides is gradually reduced from bottom to top. In order to facilitate the placement of the rectangular plate between the stop rods on the two sides, the lower ends of the stop rods are connected with the moving rod in a sliding manner, and a limiting structure is arranged between the moving rod and the stop rods. Therefore, the stop levers on the two sides can be moved outwards by the driving oil cylinder, so that the rectangular plate can be conveniently placed in; and then the stop levers on the two sides are positioned at the outermost side by using a limiting structure, and the distance between the lower ends of the stop levers on the two sides is pi D, so that the transverse reliable positioning of the rectangular plate can be ensured. When one side edge of the rectangular plate is formed into an arc-shaped bend with the radius r, the side edge is formed into a certain retraction to be separated from the stop lever. At the moment, the side stop lever can move inwards to abut against the edge of the rectangular plate through the driving oil cylinder, and then the rectangular plate is reliably positioned transversely all the time. That is to say, the rectangular plate is now positioned in the transverse direction by means of the stop face of the bar on the other side.
It should be noted that the driving cylinders on both sides can control the movement thereof through the existing electromagnetic directional valve, so as to conveniently control the moving direction of the stop levers on both sides. Certainly, the driving force of the driving oil cylinder can be conveniently regulated and controlled by adjusting the working area of the driving oil cylinder or the pressure of hydraulic oil, so that a gap is not reserved between the stop levers on the two sides of the rectangular plate, and the edge of the rectangular plate can be pried upwards along the stop surface.
Therefore, the invention has the following beneficial effects: the interference generated during pipe coiling can be effectively avoided, the processing efficiency is improved, and the manufacturing cost is reduced.
Drawings
Fig. 1 is a schematic view showing a structure of a conventional pipe winding apparatus when a stainless steel pipe is processed.
FIG. 2 is a schematic view of the present invention when one side of a bending moment coiled sheet is curved.
FIG. 3 is a schematic view of the structure of the roll bending moment plate of the present invention at the middle straight portion.
Fig. 4 is a schematic view of a positioning structure of the rectangular plate and the stop lever.
Fig. 5 is a schematic view of a configuration of the pressing device.
In the figure: 1. the device comprises a lower pressing roller 2, an upper pressing roller 3, a rectangular plate 31, a cylindrical plate 4, a pressing rod 5, a lower roller 6, an upper roller 7, a moving rod 71, a stop lever 711, a stop surface 8, a connecting support rod 9, an extrusion roller 91 and a receiving roller.
Detailed Description
The invention is further described with reference to the following detailed description and accompanying drawings.
As shown in fig. 2 and 3, a method for forming a large-diameter stainless steel tube is suitable for manufacturing a stainless steel rectangular plate 3 into a stainless steel tube with a tube diameter D and a length L by an upper pressing piece and a lower pressing piece, and comprises the following steps:
a. the stainless steel plate is cut into required rectangular plates, the length of each rectangular plate is equal to the length L of the stainless steel pipe, and the width of each rectangular plate is equal to the circumference pi D of the stainless steel pipe;
b. horizontally placing a rectangular plate on a lower pressing piece arranged on a frame, driving the upper pressing piece to move downwards by a press rod 4 to enable two side edges of the rectangular plate to form arc-shaped bends with the radius of r respectively, wherein the central angle corresponding to the bent part on one side is beta, and the width of the press rod is B;
c. the rectangular plate material is formed into a cylindrical material 31 having an opening by forming a middle straight portion of the rectangular plate material into an arc-shaped curve having the same radius as the radius of curvature of both side edges by an upper pressing member and a lower pressing member. The minimum width of the middle straight portion is B, and therefore, the maximum value of the central angle beta corresponding to the one-side bent portion is B
Therefore, the central angle beta corresponding to the unilateral bending part is controlled in the following range:
the interference between the pressing rod and the edge of the rectangular plate can be avoided when the upper pressing piece extrudes the middle flat part of the bent rectangular plate, and the upper pressing piece is moved out from one end of the cylindrical plate when the rectangular plate is conveniently bent into the cylindrical plate with the opening. On the other hand, the gap between the edge of the cylindrical material and the pressure rod is reduced as much as possible, and the cylindrical material is conveniently extruded into an opening to be closed by the extruding device. In addition, when the rectangular plate material is made into a stainless steel pipe, the pipe diameter is D, and the minimum value of the circumference (including the width of the opening part) when the rectangular plate material is made into a cylindrical material is approximately equal to pi D + B, so that the arc bending radius r of the two side edges of the rectangular plate material can be controlled in the following range: d/2 is more than or equal to r and less than or equal to 180 (pi D-2B)/pi beta, namely, the minimum value of the arc bending radius r is equal to D/2, and when the arc bending radius r is the maximum value, two side edges of the rectangular plate abut against the compression bar.
d. Extruding the outer side of the cylindrical material by using an extruding device to close the opening of the cylindrical material, and then welding the opening of the cylindrical material to form a tubular semi-finished product;
e. and rounding and straightening the semi-finished product to form the stainless steel pipe.
The method comprises the steps of splitting a stainless steel plate into required rectangular plates, horizontally placing the rectangular plates on a lower pressing piece, downwards moving an upper pressing piece to press the rectangular plates, rolling the rectangular plates into cylindrical materials with openings, welding the openings of the cylindrical materials to form tubular semi-finished products, and then rounding, straightening and the like the semi-finished products to form the stainless steel tube. Of course, the finished stainless steel tube needs to be tested by corresponding pressure tests and the like. Since the above steps and methods are prior art, they will not be described in detail herein.
The invention firstly carries out extrusion pre-bending on two sides of the rectangular plate, thereby leading the rectangular plate to form a U shape with two bent sides and straight middle, and then carries out extrusion bending on the straight middle part of the rectangular plate, thereby forming the cylindrical material with an opening. It can be understood that, when the rectangular plate is processed by pre-bending, the central angle of the bent two sides of the rectangular plate is smaller, so that the rectangular plate cannot interfere with the pressing rod of the upper pressing piece. That is, the center of the pressing rod and the center of the upper pressing member may be located in the same vertical plane, thereby preventing the pressing rod or the upper pressing member from being subjected to an eccentric moment during pressing.
In addition, the original compression roller is changed into a roller, specifically, the lower pressing piece comprises a left row of lower roller sets and a right row of lower roller sets which are symmetrically arranged, each lower roller set comprises a plurality of lower rollers 5 which are longitudinally arranged, the upper pressing piece comprises an upper roller 6 which is arranged at the lower end of the pressing rod and is positioned between the left row of lower roller sets and the right row of lower roller sets, and the axial lines of the upper roller and the lower roller are vertical to the longitudinal direction of the rack.
In this way, the rectangular plate can be conveniently moved back and forth in the longitudinal direction by a driving mechanism such as an oil cylinder or a rack and pinion, so that the rectangular plate can be extruded and bent into a cylindrical material with an opening by a press through rollers. That is, the invention can roll and bend the stainless steel plate into the long stainless steel pipe with large caliber by one press, thereby being convenient to process and manufacture by the existing equipment and being beneficial to reducing the manufacturing cost.
In this embodiment, the central angle corresponding to the curved portion is β degrees (360 ° degrees) instead of radian (2 pi radians).
Preferably, the frame is provided with a side positioning structure capable of driving the rectangular plate to move transversely and positioning, so that in step b, the side positioning structure firstly makes the rectangular plate shift to one side to make one side edge of the rectangular plate form an arc-shaped bend with radius r, at the moment, the center line of the length direction of the rectangular plate is in the horizontal direction, the eccentricity relative to the longitudinal direction of the frame is a, and then makes the rectangular plate shift to the other side with the same eccentricity a to make the other side edge of the rectangular plate form an arc-shaped bend with radius r. That is, the invention carries out extrusion pre-bending processing on the edge of the rectangular plate after the rectangular plate is transversely deviated by an eccentricity a through the side positioning structure, thereby facilitating the subsequent extrusion bending processing on the middle straight part of the rectangular plate and further forming the cylindrical material with the radius of r.
When the eccentricity a is 0.5 pi D, one side edge of the rectangular plate is just positioned in the middle of the lower pressing piece. To this end, we can control the eccentricity a to be in the following range: a is more than or equal to 0.3 pi D and less than or equal to 0.4 pi D, so that the upper pressing piece can be extruded and pre-bent from the edge of the outermost side of the rectangular plate, the flat part which is not extruded and bent is prevented from being left at the edge of the rectangular plate, and the phenomenon of 'air compression' of the upper pressing piece caused by overlarge eccentric distance is prevented.
As another preferred scheme, the circumferential surface of the upper roller is an outward convex arc-shaped ring surface with the radius equal to R, and D/2.2 is more than or equal to R and less than or equal to D/2.1.
When the rectangular plate is placed on the lower pressing piece and the upper pressing piece moves downwards to press the rectangular plate, the rectangular plate can move forwards and backwards in the longitudinal direction through the corresponding longitudinal driving mechanism, so that the rectangular plate is ensured to have smaller rolling friction resistance when moving forwards and backwards.
Particularly, the circumferential surface of the upper roller is an outer convex arc-shaped ring surface with the radius equal to R, and the radius R is controlled in the following range: d/2.2 is more than or equal to R and less than or equal to D/2.1, so that the rectangular plate can be finally rolled into arc bending with the radius R, and meanwhile, the phenomenon that the radius of the arc bending is too small is avoided, and the smooth arc bending is ensured.
Furthermore, a longitudinal driving mechanism capable of driving the rectangular plate to longitudinally move is arranged on the rack, the width of the upper roller is S, and S is more than or equal to 1.2B and less than or equal to 1.3B, and the step B comprises the following steps:
b1. the upper roller moves downwards to enable the edge of one side end of the rectangular plate to be locally bent in an arc shape with the radius of r, and the rectangular plate is in an eccentric placement state at the moment, namely the edge of one side of the rectangular plate is close to the axis of the pressure rod. Then, a longitudinal driving mechanism is used for enabling the rectangular plate to move longitudinally, so that a first arc-shaped bending belt with the radius r is formed at the edge of one side of the rectangular plate;
b2. the side positioning structure enables the rectangular plate to be shifted to the other side S, and the step b1 is repeated, so that a second arc-shaped bending belt with the radius r is formed at one side edge of the rectangular plate;
b3. repeating the step b2 until an arc-shaped bend with the radius r is formed at one side edge of the rectangular plate;
b4. repeating steps b1-b3 until an arc-shaped bend with the radius r is formed on the other side edge of the rectangular plate, wherein the side positioning structure is used for enabling the other side edge of the rectangular plate to be close to the axis position of the pressure rod.
According to the invention, the edge of one side end of the rectangular plate is locally bent into an arc with the radius r through the upper roller, then the rectangular plate is longitudinally moved by the longitudinal driving mechanism, so that the arc is bent to extend from one end of the rectangular plate to the other end, and then an arc bending belt with the radius r is formed at one side edge of the rectangular plate. That is, the upper pressing member presses the curled rectangular plate material step by step, so that the pressure required by the press can be remarkably reduced, the specification of the press can be reduced, and the manufacturing cost can be reduced.
In addition, the offset of the rectangular plate is equal to the width S of the upper roller, so that the continuity between adjacent arc-shaped bending belts on the rectangular plate can be ensured, and the smooth forming of arc-shaped bending with the radius r at the edge of the rectangular plate is facilitated.
In particular, the present invention makes the width of the upper roller slightly larger than that of the pressing rod, so that the upper roller can be bent from the middle of the straight portion of the rectangular plate in step c, thereby preventing the bent portions at both sides from interfering with the pressing rod. When the rectangular plate is bent into the cylindrical material, the upper roller can be moved out from any end of the cylindrical material.
Preferably, as shown in fig. 4, the side positioning structure includes a plurality of moving rods 7 arranged on the frame in a laterally movable manner, the moving rods are connected to form an integral frame structure through connecting support rods 8, a power unit for driving the connecting support rods to move left and right is arranged on the frame, two ends of the moving rods are respectively provided with stop rods 71 extending upwards, the stop rods at the two ends are arranged oppositely, the distance between the lower ends of the stop rods is matched with the width (pi D) of the rectangular plate, the inner sides of the stop rods opposite to each other are curved inwards from the lower end connected with the moving rods to the upper end, so that a stop surface 711 with a central angle theta is formed, and
the radius of the stop surface is: a + π D/2.
In step b1, the rectangular plate is horizontally placed on the lower pressing member, two sides of the rectangular plate respectively abut against the lower end of the stop lever on one corresponding side, so that the rectangular plate is transversely positioned, then the power unit drives the movable rods on the left side and the right side to move to one side through the connecting support rod, and the rectangular plate is eccentrically positioned on the rack; in step b2, the stop lever on the side away from the upper press member axis pushes the rectangular plate to shift S to the other side.
It should be noted that the distance between the upper ends of the two stop surfaces is smaller than the width of the rectangular plate, so that the rectangular plate can be obliquely inserted into the gap between the upper ends of the two stop surfaces and placed on the lower pressing member.
It should be noted that the longitudinal driving mechanism and the power unit may be an oil cylinder, a motor, a gear and a rack, and other existing mechanisms, and will not be described in detail in this embodiment.
When one side of the rectangular plate is extruded and bent to form the arc-shaped bent belt, the edge of the other side of the rectangular plate can be bent upwards to form an arc-shaped bulge. It can be found by calculation that the central angle theta corresponding to the arc-shaped tilting of the other side edge is substantially equal to
Accordingly, the radius of the curved raised edge is approximately equal to a + π D/2. Therefore, the inner side of the stop lever is provided with the arc-shaped bent stop surface with the central angle equal to theta and the radius of a + pi D/2, so that the edge of the upward arc-shaped tilting side of the rectangular plate can be always limited by the stop lever, and the rectangular plate is ensured to have stable eccentricity.
In order to facilitate the extrusion of the cylindrical material, as shown in fig. 5, the extrusion device comprises extrusion roller sets positioned at two sides of the frame, each extrusion roller set comprises a plurality of extrusion rollers 9 uniformly distributed along the longitudinal direction, the axes of the extrusion rollers are vertically arranged, the circumferential surface of each extrusion roller is an inward concave arc-shaped ring surface with the radius equal to D/2, and the distance from the first extrusion roller to the last extrusion roller of the extrusion roller sets at two sides is gradually reduced from (D + B/pi) to D.
It can be known from the foregoing that the diameter of the cylindrical material with the opening is slightly larger than the pipe diameter D, and when we place the cylindrical material between the extrusion roller sets at the two sides of the frame, the extrusion roller sets at the two sides move relatively to extrude the outer side of the cylindrical material, so that the diameter of the cylindrical material is reduced, and the opening is closed, so as to weld the opening.
Particularly, the distance between the first extrusion roller and the last extrusion roller of the two-side extrusion roller set of the invention is gradually reduced from (D + B/pi) to D, namely, the distance between the last extrusion roller is just equal to the pipe diameter D, and the distance between the first extrusion roller is greater than the pipe diameter D + B/pi, so that the cylindrical material can be conveniently sent into the gap between the first pair of extrusion rollers, when the extrusion rollers rotate relatively, on one hand, the extrusion necking effect can be formed on the cylindrical material, and on the other hand, the cylindrical material can be driven to move forwards. After the cylindrical material is extruded and necked by the last pair of extrusion rollers, the cylindrical material with the diameter D can be formed, and the opening of the cylindrical material can be welded at the moment. That is, the cylindrical material may be welded while being squeezed and constricted.
Of course, the receiving roller set for receiving the cylindrical material may be disposed on the frame, and the receiving roller set includes a plurality of receiving rollers 91 uniformly distributed along the longitudinal direction.
In order to facilitate the eccentric arrangement of the rectangular plate, the lower end of the stop rod is connected with the moving rod in a sliding mode, a driving oil cylinder (not shown in the figure) for driving the stop rod to slide is arranged on the moving rod, and a limiting structure is further arranged between the moving rod and the stop rod, so that the stop rod can be positioned at the outermost side. When the stop levers on the two sides are positioned at the outermost side, the distance between the lower ends of the stop levers on the two sides is the width (pi D) of the rectangular plate.
Thus, in step b1, the stop bars on both sides may be positioned at the outermost position, and then the rectangular plate may be horizontally placed on the lower pressing member, the both sides of the rectangular plate respectively abut against the lower end of the stop bar on one corresponding side, and when one side edge of the rectangular plate forms an arc-shaped bending belt with a radius r, the edge on the other side of the rectangular plate tilts up along the stop surface of the stop bar on one corresponding side.
It can be understood that, when the inner side of the blocking rod is an arc-shaped blocking surface, the distance between the blocking rods on the two sides is gradually reduced from bottom to top. In order to facilitate the placement of the rectangular plate between the stop rods on the two sides, the lower ends of the stop rods are connected with the moving rod in a sliding manner, and a limiting structure is arranged between the moving rod and the stop rods. Therefore, the stop levers on the two sides can be moved outwards by the driving oil cylinder, so that the rectangular plate can be conveniently placed in; and then the stop levers on the two sides are positioned at the outermost side by using a limiting structure, and the distance between the lower ends of the stop levers on the two sides is pi D, so that the transverse reliable positioning of the rectangular plate can be ensured. When one side edge of the rectangular plate is formed into an arc-shaped bend with the radius r, the side edge is formed into a certain retraction to be separated from the stop lever. At the moment, the side stop lever can move inwards to abut against the edge of the rectangular plate through the driving oil cylinder, and then the rectangular plate is reliably positioned transversely all the time. That is to say, the rectangular plate is now positioned in the transverse direction by means of the stop face of the bar on the other side.
It should be noted that the driving cylinders on both sides can control the movement thereof through the existing electromagnetic directional valve, so as to conveniently control the moving direction of the stop levers on both sides. Certainly, the driving force of the driving oil cylinder can be conveniently regulated and controlled by adjusting the working area of the driving oil cylinder or the pressure of hydraulic oil, so that a gap is not reserved between the stop levers on the two sides of the rectangular plate, and the edge of the rectangular plate can be pried upwards along the stop surface.
In addition, limit structure can be including setting up the spout on the carriage release lever, when the pin removed to the spout outer end along the spout, can make the pin location in the outside position, owing to there are many current slide positioning (limit) structures, does not do not detailed description in this embodiment yet.
Claims (7)
1. A forming method of a large-diameter stainless steel pipe is suitable for manufacturing a stainless steel rectangular plate into a stainless steel pipe with the pipe diameter of D through an upper pressing piece and a lower pressing piece, and is characterized by comprising the following steps:
a. the stainless steel plate is disassembled and cut into required rectangular plates, the length of each rectangular plate is equal to that of the stainless steel pipe, and the width of each rectangular plate is equal to the perimeter of the stainless steel pipe;
b. the rectangular plate is horizontally placed on a lower pressing piece arranged on the frame, the press drives the upper pressing piece to move downwards through a pressing rod,
the two side edges of the rectangular plate are respectively formed into arc-shaped bends with the radius of r, the central angle corresponding to the single-side bent part is beta, the width of the pressure bar is B, and
c. using an upper pressing piece and a lower pressing piece to enable the middle straight part of the rectangular plate to form arc-shaped bending with the same bending radius as the edges of the two sides, so that the rectangular plate is formed into a cylindrical material with an opening;
d. extruding the outer side of the cylindrical material by using an extruding device to close the opening of the cylindrical material, and then welding the opening of the cylindrical material to form a tubular semi-finished product;
e. and rounding and straightening the semi-finished product to form the stainless steel pipe.
2. The method as claimed in claim 1, wherein the frame is provided with a side positioning structure for driving the rectangular plate to move laterally and positioning, in step b, the side positioning structure first deflects the rectangular plate to one side to form an arc-shaped curve with a radius r at one side edge of the rectangular plate, the center line of the rectangular plate in the length direction is a in the horizontal direction with an eccentricity relative to the longitudinal direction of the frame, and then deflects the rectangular plate to the other side by a to form an arc-shaped curve with a radius r at the other side edge of the rectangular plate, and 0.3 pi D is greater than or equal to a and is less than or equal to 0.4 pi D.
3. The method as claimed in claim 2, wherein the press member comprises two rows of lower roller sets symmetrically arranged, the lower roller set comprises a plurality of lower rollers arranged along the longitudinal direction, the upper press member comprises an upper roller arranged at the lower end of the press rod and positioned between the two rows of lower roller sets, the axes of the upper roller and the lower roller are perpendicular to the longitudinal direction of the frame, the circumferential surface of the upper roller is an outer convex arc-shaped ring surface with the radius equal to R, and D/2.2 is greater than or equal to R and is less than or equal to D/2.1.
4. The forming method of large-caliber stainless steel tubes as claimed in claim 3, wherein the machine frame is provided with a longitudinal driving mechanism, the width of the upper roller is S, and S is more than or equal to 1.2B and less than or equal to 1.3B, and the step B comprises:
b1. the upper roller moves downwards to enable the edge of one side end of the rectangular plate to be locally bent in an arc shape with the radius r, and then the rectangular plate is longitudinally moved by a longitudinal driving mechanism, so that a first arc-shaped bending belt with the radius r is formed at the edge of one side of the rectangular plate;
b2. the side positioning structure enables the rectangular plate to be shifted to the other side S, and the step b1 is repeated, so that a second arc-shaped bending belt with the radius r is formed at one side edge of the rectangular plate;
b3. repeating the step b2 until an arc-shaped bend with the radius r is formed at one side edge of the rectangular plate;
b4. and repeating the steps b1-b3 until an arc-shaped bend with the radius r is formed at the other side edge of the rectangular plate.
5. The method as claimed in claim 4, wherein the side positioning structure comprises a plurality of moving rods transversely movably disposed on a frame, the moving rods are connected to form an integral frame structure through connecting support rods, a power unit for driving the connecting support rods to move left and right is disposed on the frame, two ends of the moving rods are respectively provided with a stop rod extending upward, the distance between the lower ends of the stop rods is pi D, the inner side of each stop rod opposite to the inner side forms an arc-shaped curved stop surface with a central angle theta from the lower end connected with the moving rod to the upper end, and the stop surfaces are curved inward
The radius of the stop surface is: a + pi D/2, in the step b1, horizontally placing a rectangular plate on the lower pressing piece, respectively abutting two sides of the rectangular plate against the lower end of the stop lever on one corresponding side, driving the moving rods on the left side and the right side to move to one side by the power unit through the connecting support rod, and then eccentrically positioning the rectangular plate on the rack; in step b2, the stop lever on the side away from the upper press member axis pushes the rectangular plate to shift S to the other side.
6. The method as claimed in claim 1, wherein the extruding means comprises a plurality of extruding roller sets disposed at both sides of the frame, each extruding roller set comprises a plurality of extruding rollers uniformly distributed along the longitudinal direction, the circumferential surface of the extruding roller is an inward concave arc ring surface with a radius equal to D/2, and the distance between the first extruding roller and the last extruding roller of the extruding roller sets at both sides is gradually reduced from (D + B/pi) to D.
7. The method as claimed in claim 5, wherein the lower end of the stopper rod is slidably connected to the moving rod, the moving rod is provided with a driving cylinder for driving the stopper rod to slide, a position limiting structure is further provided between the moving rod and the stopper rod, so that the stopper rod can be positioned at an outermost position, when the stopper rods at both sides are positioned at the outermost position, the distance between the lower ends of the stopper rods at both sides is pi D, in step b1, the stopper rods at both sides are positioned at the outermost position, then the rectangular plate is horizontally placed on the lower pressing member, both sides of the rectangular plate respectively abut against the lower end of the stopper rod at a corresponding side, and when one side edge of the rectangular plate forms the curved zone having the radius r, the edge of the rectangular plate is raised along the stop surface of the stopper rod at the corresponding side.
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| AT223915B (en) * | 1959-12-10 | 1962-10-25 | Alfred Ing Woegerbauer | Method and device for the continuous production of profiles, in particular pipes |
| CA2165267A1 (en) * | 1994-12-16 | 1996-06-17 | Hirotaka Nishida | Pressure roll, molding apparatus using the pressure roll, and process for manufacturing the pressure roll |
| CN102049435B (en) * | 2010-10-30 | 2012-11-07 | 泰安市华泰锻压机械有限公司 | Roll bending method and electrical control device for three-roll plate bending machine |
| CN104815881A (en) * | 2015-05-21 | 2015-08-05 | 江苏一机机械科技有限公司 | Bending method for three-roller plate bending machine |
| JP6500810B2 (en) * | 2016-03-01 | 2019-04-17 | Ｊｆｅスチール株式会社 | Manufacturing method of ERW welded clad steel pipe |
| CN106345857B (en) * | 2016-09-29 | 2019-03-08 | 哈尔滨工业大学 | A kind of method that flat section approaches circular arc |
| CN108704960A (en) * | 2018-05-18 | 2018-10-26 | 燕山大学 | A kind of symmetrical expression four-roller roll bending control method |
| CN108906929B (en) * | 2018-07-11 | 2020-05-08 | 安徽太平洋重型机器股份有限公司 | Numerical control hydraulic plate rolling machine for ship |
| CN112718963B (en) * | 2020-12-18 | 2022-09-27 | 广州永大不锈钢有限公司 | Method and device for bending large-diameter stainless steel pipe |
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Denomination of invention: A Forming Method of Large Diameter Stainless Steel Pipe Effective date of registration: 20230206 Granted publication date: 20220920 Pledgee: Ping An Bank Ltd Wenzhou branch Pledgor: GANYEAH HOLDING GROUP CO.,LTD. Registration number: Y2023330000298 |