Patent Publication Number: US-10780487-B2

Title: Bending and molding production line

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a National Stage Entry of PCT/CN2016/074209, filed Feb. 22, 2016, which claims priority to Chinese Application No. 201510170509.5, filed Apr. 13, 2015. The disclosures of the prior applications are hereby incorporated by reference herein in their entireties. 
     BACKGROUND 
     Technical Field 
     The present invention relates to a bending and molding production line. 
     Related Art 
     For the bending and molding production line of a tubular product such as an air conditioner tube and an engine oil tube, a tubular product coil material is required to be straightened into a material with certain straightness, and is then bent and molded. At present, such bent tubular product is widely applied to the field of engines, in particular an oil path in an aerospace airspace engine, a ship engine and a vehicle engine. But since the bending precision of the tubular product is low or a residual stress is overlarge, a workpiece is failed, which leads to a loss of social properties. 
     A complete tubular product automatic bending production line comprises an unwinding mechanism, a feeding and straightening device, a cutting-off mechanism, a bending and molding device and a material loading mechanism for transferring the tubular product to the bending and molding device from the cutting-off mechanism. However, the existing such type of devices difficultly constitute an automatic bending production line with a high precision and a high production efficiency. The causes are as follows: 
     Firstly, a traditional single-head bending device is lower in efficiency due to a lower bending speed. At present, some dual-head bending devices are emerged on the market, but most of the existing dual-head bending mechanisms can realize symmetric bending instead of asymmetric machining, and the machining efficiency is low; meanwhile, the maintenance of a power part is large in mounting and dismounting work amount, efficient replacement and maintenance are hard to realize, and a low working efficiency is caused. For example, the patent with a patent number 201020147236.5 discloses a tube bending machine, a bending device thereof can realize symmetric bending only and cannot provide the machining of asymmetric tubes and tubular products. For example, the patent with a patent number 201020595165.5, discloses a tube bending machine, a power part of a bending device thereof is relatively complex to mount and dismount, and efficient maintenance is hard to realize, which leads to a low working efficiency. 
     In addition, the bending and molding device is required to be provided with a clamping mechanism which clamps and rotates the tubular product to realize the space bending of the tubular product. But the existing clamping device is relatively complex in structure and difficult to machine and mount, a power transmission system is instable, a rotation precision is lower, causing that a finished product of the tubular product does not meet the requirements. For example, the Chinese Patent with a patent number CN 203281764 U discloses an automatic bending machine, such bending machine adopts a rotation clamping mechanism capable of rotating around the axis of a metal tubular product by 360 degrees, but a shearing mechanism and a bending mechanism of the device are also located on the rotation mechanism, causing that the whole device is very complex in structure and is unfavorable for mounting, and the device is larger in power demand and higher in manufacture cost. 
     For a conventional storing and feeding device for a coiled tubular product, in a use process, when a discharging speed of the tubular product is larger than or smaller than a receiving speed of a machining device, the tubular product has a phenomenon of bending and extruding or a gradually increased tension, cannot be automatically restored, and can work only after an artificial solution, and not only is the production efficiency reduced, but also a manual cost is increased. 
     SUMMARY 
     The present invention aims to solve the technical problem about providing a bending and molding production line, which can bend two sides of a tubular product or wire stock at different bending angles and different bending radii and has a high working efficiency. 
     In order to solve the above problem, the technical solution adopted by the present invention is: a bending and molding production line, comprising an unwinding mechanism, a feeding and straightening device, a cutting-off mechanism, a bending and molding device and a material loading mechanism for transferring the tubular product to the bending and molding device from the cutting-off mechanism, wherein the bending and molding device comprises a base, the base is provided with a transverse sliding rail, two transverse sliding bases are disposed on the transverse sliding rail in a sliding manner, the base is provided with a transverse driving device driving the transverse sliding bases, the base is provided with a central clamping device which can clamp the tubular product and can rotate around a central axis of the tubular product between the two transverse sliding bases, the transverse sliding bases are provided with a longitudinal sliding rail, the longitudinal sliding rail is provided with a longitudinal sliding base, the transverse sliding bases are provided with a longitudinal driving device driving the longitudinal sliding base to slide, the longitudinal sliding base is provided with a bending and molding device, one side, close to the central clamping device, of the transverse sliding base at the left side is provided with a left clamping device capable of movably extending to clamp the tubular product, one side, close to the central clamping device, of the transverse sliding base at the right side is provided with a right clamping device capable of movably extending to clamp the tubular product, the bending and molding mechanism comprises a hollow mounting base rotatably disposed on the longitudinal sliding base, a hollow shaft is rotatably disposed in the mounting base in a penetrating manner, a mandrel is rotatably disposed in the hollow shaft in a penetrating manner, a longitudinal sliding base extends out of one ends of the hollow shaft and the mandrel, the hollow shaft is provided with a moving bending head at this end, the end part of the moving bending head is cylindrical and its periphery is provided with a circle of groove matched with the tubular product to be matched, the mandrel is detachably provided with a fixed bending die at this end, the fixed bending die is provided with four cylindrical fixed bending modules of which the connecting lines are in a rectangle, an interval between two rows of fixed bending modules is matched with a diameter of the tubular product to be bent, the other end of the mandrel is connected to a fixed die motor disposed on the longitudinal sliding base, a driven synchronous bent wheel sleeves the periphery of the other end of the hollow shaft, the longitudinal sliding base is provided with a moving die motor, an output shaft of the moving die motor is provided with a driving synchronous belt wheel matched with the driven synchronous belt wheel, and a synchronous belt sleeves the driven synchronous belt wheel and the driving synchronous belt wheel. 
     The left clamping device comprises a left base disposed on the longitudinal sliding base at the left side, a certain included angle exists between the upper surface of the longitudinal sliding base and the left base, the upper surface of the left base is provided with a left sliding rail, the left sliding rail is provided with a left sliding base, the left sliding base is provided with a left mounting base, the left mounting base is provided with a clamping component driven by a clamping cylinder to open or clamp, and the left base is provided with a sliding cylinder driving the left sliding base to drive the clamping component to approach to the tubular product from bottom to top; the right clamping device comprises a right base disposed on the longitudinal sliding base at the right side, a certain included angle exists between the upper surface of the longitudinal sliding base and the right base, the right base is provided with a right sliding rail, the right sliding rail is provided with a right sliding base, the right sliding base is provided with a right mounting base, the right mounting base is provided with a clamping component driven by a clamping cylinder to open or clamp, and the right base is provided with a sliding cylinder driving the right sliding base to drive the clamping component to approach to the tubular product from top to bottom; and the bending and molding mechanism is disposed in the position of the longitudinal sliding base close to the central clamping device as much as possible. 
     The present invention aims to solve the technical problem about providing a bending and molding production line with a high precision. 
     In order to solve the technical problem, the technical solution adopted by the present invention is: the central clamping device comprises a box body, a rotary gear disk rotatably disposed on the box body, a power device disposed on the box body, a transmission mechanism connected to the rotary gear disk and the power device, and a clamping mechanism disposed on the rotary gear disk for clamping the tubular product, wherein the rotary gear disk is provided with a containing notch penetrating through the center of the rotary gear disk; the clamping mechanism comprises a left clamping block and a right clamping block; the left clamping block and the right clamping block are symmetric and the bottom ends are hinged to a disk surface of the rotary gear disk; the upper parts at opposite sides of the left clamping block and the right clamping block are provided with a left chuck and a right chuck respectively; the axis of the tubular product clamped by the left chuck and the right chuck is coincided with a central axis of the rotary gear disk; the lower part of the left clamping block located on the left chuck is provided with a left pushing block, the lower part of the right clamping block located on the right chuck is provided with a right pushing block, the upper parts of one sides, back onto each other, of the left clamping block and the right clamping block are connected to the rotary gear disk by a left tension spring and a right tension spring respectively, and a pull force of the left tension spring and the right tension spring drives the left chuck and the right chuck to abut against each other; the lower part of the disk surface of the rotary gear disk located on the left pushing block and the right pushing block is provided with a reset pushing rod, the box body is provided with a reset oil cylinder driving the reset pushing rod to move, the reset pushing rod pushes the left pushing block and the right pushing block when pushes upward, such that the left clamping block and the right clamping block rotate to separate the left chuck from the right chuck; the transmission mechanism comprises a left transition gear and a right transition gear disposed on two sides of the reset oil cylinder in the box body respectively and meshed with the rotary gear disk, a left transmission gear meshed with the left transition gear and a right transmission gear meshed with the right transition gear are disposed in the box body, a left synchronous belt coaxial and capable of synchronous rotating with the left transmission gear and a right synchronous belt coaxial and capable of synchronous rotating with the right transmission gear are further disposed in the box body, the output shaft of the power device is fixedly connected to a main synchronous belt wheel, and a synchronous belt sleeves the main synchronous belt wheel, the left synchronous belt wheel and the right synchronous belt wheel. 
     The present invention solves the technical problem about providing a bending and molding production ling with a high degree of automation. 
     In order to solve the technical problem, the technical solution adopted by the present invention is: the box body is further provided with a poking mechanism for unloading, the poking mechanism comprises a main poking shaft vertical to the rotary gear disk and rotatably connected to the box body, two ends of the main poking shaft extend out of the box body and are connected to a poking arm which pokes the tubular product out of the containing notch respectively when rotating, a main poking gear is fixedly disposed on the main poking shaft in the box body, a slave poking gear meshed with the main poking gear is rotatably disposed in the box body, a poking gear shaft is rotatably disposed in the box body, a third poking gear meshed with the slave poking gear is fixedly disposed on the poking gear shaft, a poking cylinder is disposed under the third poking gear in the box body, a rack is disposed at the end part of a piston rod of the poking cylinder, the rack is meshed with a poking driving gear fixedly sleeving the poking gear shaft, and the upper part of the reset oil cylinder in the box body is further provided with a poking oil cylinder capable of driving the reset pushing rod to move. 
     As a preferable solution, the longitudinal driving device comprises a longitudinal servomotor disposed on the transverse sliding base, the longitudinal sliding base is provided with a longitudinal lead screw, and the longitudinal servomotor is connected to the end part of the longitudinal lead screw by a coupler. 
     As a preferable solution, the transverse driving device comprises a rack disposed on the base, the transverse sliding base is provided with a transverse driving motor, and an output shaft of the transverse driving motor downwards penetrates out of the transverse sliding base and is connected to a synchronous belt wheel matched with the rack. 
     As a preferable solution, the unwinding mechanism comprises a box type base, a motor and a speed reducer connected to the motor are disposed in the base, a material disc is rotatably disposed on the base, the speed reducer drives the material disc to rotate, the material disc is provided with a central rod coaxial with an output shaft of the speed reducer, the material disc is provided with at least three blocking rods, the blocking rods are uniformly distributed around the central rod, the base is also fixedly connected to a bottom plate, the bottom plate is rotatably provided with a revolution bottom plate, the bottom plate and the revolution bottom plate are rotatably connected by a rotary shaft, the rotary shaft is parallel with the central rod, a reset spring is further disposed between the bottom plate and the revolution bottom plate, one end of the reset spring is fixedly connected on the bottom plate, the other end of the reset spring is fixedly connected to the revolution bottom plate, the upper surface of the revolution bottom plate is connected to a treading rod guiding a moving trend of the tubular product, the treading rod and the central rod are matched, the top end of the treading rod is provided with a limiting device preventing the tubular product from being separated from the treading rod, the revolution bottom plate is further provided with an angle measuring sensor for measuring a swing angle of the treading rod, the base is provided with a controller electrically connected to the angle measurement sensor, and the controller is used for controlling operation of the motor. 
     As a preferable solution, the feeding straightening device comprises a rack, the rack is provided with two pairs of feeding wheels, a straightening mechanism and a length fixing mechanism along a straight line in sequence, a wire passing base is disposed at the front part of the feeding wheels, between the two pairs of the feeding wheels and between the feeding wheels and the straightening mechanism on the rack respectively, the straightening mechanism comprises a hollow shaft-like straightening component rotatably disposed on the rack and a straightening power system driving the hollow shaft-like straightening component to rotate, the hollow shaft-like straightening component comprises a hollow left end shaft, at least three straightening dies and a hollow right end shaft, the left end shaft and the right end shaft are rotatably disposed on the rack respectively, a connecting block with a material passing hole in the middle is disposed among the adjacent straightening dies, the positions of the straightening dies meet a condition that the central lines of all straightening dies are in staggered arrangement relative to the axis of the left end shaft, the straightening die comprises two straightening modules provided with semicircular slots matched with the diameter of the tubular product to be straightened, connecting surfaces of the left end shaft, the connecting blocks and the right end shaft matched with the straightening dies are provided a mounting groove matched with the shape of the straightening die and an arc slot located for compressing compression bolts of the straightening dies and internally provided with a plurality of threaded sections respectively, the length fixing mechanism comprises a pair of measuring wheels driven by the tubular product to rotate and placed on the rack, and one of the measuring wheels is connected to a revolution encoder. 
     As a preferably solution, the cutting-off mechanism comprises a mounting base, the mounting base is provided with two upright plates vertical to each other, one upright plate is provided with a fixed shearing head, the other upright plate parallel with a feeding direction is provided with a shearing oil cylinder and the end part of the piston rod of the shearing oil cylinder is provided with a moving shearing head matched with the fixed shearing head. 
     As a preferable solution, the material loading mechanism comprises two end part mounting frames disposed on two ends of the base of the bending and molding device respectively, the end part mounting frames are rotatably provided with a transmission shaft and a charging power device driving the transmission shaft, the transmission shaft is provided with at least two material holding arms in parallel, the end part of each material holding arm is provided with a pneumatic clamping component which is controlled by a cylinder to open or clamp, and the positions of the material holding arms are matched with the positions where the cutting-off mechanism and the central camping mechanism charge the tubular product. 
     The present invention has the beneficial effects: since in the bending and molding device, the central clamping device is adopted to clamp the tubular product, and a dual-head single bending manner is adopted, the two ends can meet the requirements of different bending angles, bending radii and bending lengths, the asymmetric bending of the tubular product can be realized, the working flexibility of the bending machine is improved, and the working efficiency is greatly improved. 
     Since the clamping device is adopted beside the bending and molding device and plays a role of locating the tubular product, the tubular product in the position close to the bending and molding device is prevented from generating unnecessary bending deformation, such that the product quality is ensured. 
     Since the clamping component of the clamping device is driven by the cylinder, such that in the bending process, the tubular product is stably bent, the vibration generated during bending is reduced, and the working reliability of the whole device is improved. 
     Since the hollow shaft is provided with the moving bending head, the mandrel is detachably provided with the fixed bending die, and the central shaft and the mandrel are respectively driven by an external power connecting device, the whole structure is simple and convenient to mount. 
     Since the transmission mechanism of the central clamping device comprises the left transition gear and the right transition gear which are disposed at two sides of the reset oil cylinder in the box body and meshed with the rotary gear disk respectively, due to a driving manner of the two transition gears, the rotation of the rotation gear disk is more stable, a rotation error possibly caused by a gear side gap in a forward and backward rotation process due to the driving from single side gears is avoided, such that the device is higher in rotation precision, error accumulation is avoided, and therefore, the bending quality of the tubular product is improved; and the driving of the synchronous belt and the synchronous belt wheel is adopted, such that the advantages of buffering and damping, stable transmission and convenience in maintenance are realized. 
     The clamping mechanism adopts a spring self-clamping structure, and is simple in structure and stable in clamping force, the oil cylinders are only disposed in the charging position and poking position, the clamping mechanism can be only opened by push of the piston rod, the separation between the power and structure is realized, and the stability of the clamping mechanism in a rotation process of the rotary gear disk is ensured. 
     Since the central clamping device is provided with the poking mechanism, the effects of automatic unloading, improved degree of automation and reduced labor cost are realized. 
     Since the unwinding device adopts the angle measuring sensor disposed on the swingable treading rod, when the tension of the tubular product in conveying is increased to draw the treading rod to swing by a certain angle, the angle measuring sensor can send a signal to the controller, and the controller can control the motor to start to release a coil on the material disc, such that the tension of the tubular product in conveying is relieved and the tubular product is prevented from being snapped by a machining device; when the machining device stops receiving the tubular product, the motor continues to rotate, the tension of the tubular product is reduced till lost, after an action force of the tubular product on the treading rod is lost, the treading rod is pulled to the original position by the reset spring, the angle measuring sensor resends the signal to the controller, which controls the motor to stop rotating, and in this way, the tubular product is prevented from being knotted. The whole working process needs no artificial maintenance, the technical effects of automatically stopping feeding when the machining device stops receiving the tubular product and automatically starting feeding when the machining device is started to receive the tubular product, and the degree of automation of the production line is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a three-dimensionally structural schematic view of the present invention. 
         FIG. 2  is a main structural schematic view of the present invention. 
         FIG. 3  is a top structural schematic view of the present invention. 
         FIG. 4  is an enlarged structural schematic view of an A part in  FIG. 2 . 
         FIG. 5  is an enlarged structural schematic view of a B part in  FIG. 4 . 
         FIG. 6  is an enlarged structural schematic view of an A direction in  FIG. 2 . 
         FIG. 7  is a structural schematic view of a cutting-off mechanism of the present invention. 
         FIG. 8  is a structural schematic view of an unwinding mechanism of the present invention. 
         FIG. 9  is a top view of  FIG. 8 . 
         FIG. 10  is an enlarged view of an A part in  FIG. 8 . 
         FIG. 11  is an enlarged view of a B part in  FIG. 9 . 
         FIG. 12  is a structural schematic view of a bending and molding device in the present invention. 
         FIG. 13  is a top structural schematic view of a transverse sliding base and parts thereon at the left side in the bending and molding device. 
         FIG. 14  is a structural schematic view of an end surface of a bending and molding device at the right side in the bending and molding device. 
         FIG. 15  is a right structural schematic view of the transverse sliding base and the parts thereon at the left side in the bending and molding device. 
         FIG. 16  is a left structural schematic view of a transverse sliding base and parts thereon at the right side in the bending and molding device. 
         FIG. 17  is a main sectional view of a central clamping device in the present invention; 
         FIG. 18  is an enlarged schematic view of a clamping mechanism in  FIG. 17 ; 
         FIG. 19  is a right schematic view of  FIG. 17 ; 
         FIG. 20  is a left view of  FIG. 17 ; 
         FIG. 21  is an enlarged view of an A part in  FIG. 19 ; and 
         FIG. 22  is an enlarged view of a B part in  FIG. 17 . 
     
    
    
     In  FIGS. 1-22 :  1  unwinding mechanism,  11  base,  12  motor,  13  speed reducer,  14  material disc,  15  central rod,  16  blocking rod,  161  bending part,  17  bottom plate,  18  revolution bottom plate,  19  limiting device,  110  reset spring,  111  treading rod,  112  angle measuring sensor,  113  controller,  114  guiding heel,  115  blocking piece,  116  press disc,  117  spring fixing nail,  119  tubular product,  120  rotary shaft; 
       2  feeding straightening device,  21  rack,  22  feeding wheel,  23  straightening mechanism,  25  wire passing base,  231  straightening component,  232  straightening power system,  233  left end shaft,  234  straightening die,  235  left end shaft,  236  connecting block,  237  compression bolt,  24  length fixing mechanism,  241  measuring wheel,  242  revolution encoder; 
       3  cutting-off mechanism,  31  mounting base,  32  upright plate,  33  fixed shearing head,  34  shearing oil cylinder,  35  moving shearing head; 
       4  bending and molding device,  41  base,  42  transverse sliding rail,  43  transverse sliding base,  44  transverse driving device,  441  transverse driving motor,  442  gear,  45  central clamping device,  46  longitudinal sliding rail,  47  longitudinal sliding base,  48  longitudinal driving device,  481  longitudinal driving motor,  482  longitudinal lead screw,  483  coupler,  49  bending and molding device,  491  mounting base,  492  hollow shaft,  493  mandrel,  494  moving bending head,  495  fixed bending die,  496  fixed die motor,  497  driven synchronous belt wheel,  498  moving die motor,  499  main synchronous belt wheel,  410  left clamping device,  4101  left base,  4102  left sliding rail,  4103  left sliding base,  4104  left mounting base,  4105  clamping component,  4106  sliding cylinder,  411  right clamping cylinder,  4111  right base,  4112  right sliding rail,  4113  right sliding rail,  4114  right mounting base,  4115  clamping component  4116  sliding cylinder. 
       71  box body,  72  rotary gear disk,  73  power device,  731  servomotor,  732  right angle speed reducer,  74  transmission mechanism,  741  main synchronous belt wheel,  742  left synchronous belt wheel,  743  right synchronous belt wheel,  744  left transition gear,  745  right transition gear,  746  synchronous belt,  747  left transmission gear,  748  right transmission gear,  75  clamping mechanism,  751  left clamping block,  7511  left chuck,  7512  left pushing block,  752  right clamping block,  7521  right chuck,  7522  right pushing block,  753  left tension spring,  754  right tension spring,  755  reset pushing rod,  756  reset oil cylinder,  76  poking mechanism,  761  main poking shaft,  762  poking transmission shaft,  763  poking gear shaft,  764  main poking gear,  765  slave poking gear,  766  third poking gear,  767  poking cylinder,  768  rack,  769  rack compressing device,  7691  compressing shaft,  7692  idler wheel,  77  poking arm,  78  poking oil cylinder,  79  first transition shaft,  710  second transition shaft. 
       5  material loading mechanism,  51  end part mounting frame,  52  transmission shaft,  53  material holding arm,  54  pneumatic clamping component. 
     DETAILED DESCRIPTION 
     Specific implementing solutions of the present invention are described in detail in combination with the drawings. 
     As shown in  FIGS. 1-3 , a bending and molding production line comprises an unwinding mechanism  1 , a feeding and straightening device  2 , a cutting-off mechanism  3 , a bending and molding device  4  and a material loading mechanism  5  for transferring the tubular product to the bending and molding device from the cutting-off mechanism. 
     As shown in  FIGS. 8-11 , the unwinding mechanism  1  comprises a box type base  11 , a motor  12  and a speed reducer  13  connected to the motor  12  are disposed in the base  11 , a material disc  14  is rotatably disposed on the base  11 , the speed reducer  13  drives the material disc  14  to rotate, the material disc  14  is provided with a central rod  15  coaxial with an output shaft of the speed reducer  13 , the material disc  14  is provided with at least three blocking rods  16 , the blocking rods  16  are uniformly distributed around the central rod  15 , the base  11  is also fixedly connected to a bottom plate  17 , the bottom plate  17  is rotatably provided with a revolution bottom plate  18 , the bottom plate  17  and the revolution bottom plate  18  are rotatably connected by a rotary shaft  120 , the rotary shaft  120  is parallel with the central rod  15 , a reset spring  110  is further disposed between the bottom plate  17  and the revolution bottom plate  18 , one end of the reset spring  110  is fixedly connected on the bottom plate  17 , the other end of the reset spring is fixedly connected to the revolution bottom plate  18 , the upper surface of the revolution bottom plate  18  is connected to a treading rod  111  guiding a moving trend of the tubular product, the treading rod  111  and the central rod  15  are matched, the top end of the treading rod  111  is provided with a limiting device  19  preventing the tubular product from being separated from the treading rod  111 , the revolution bottom plate  18  is further provided with an angle measuring sensor  112  for measuring a swing angle of the treading rod  111 , the base  11  is provided with a controller electrically connected to the angle measurement sensor  112 , and the controller  113  is used for controlling operation of the motor  12 . 
     When the tension of a tubular product  119  in conveying is increased to draw the treading rod  111  to swing by an angle, the angle measuring sensor  112  can send a signal to the controller  113 , and the controller  113  can control the motor  12  to start to release a coil  118  on the material disc  14 , such that the tension of the tubular product  119  in conveying is relieved and the tubular product  119  is prevented from being snapped by a machining device; when the machining device stops receiving the tubular product  119 , the motor  12  continues to rotate, the tension of the tubular product  119  is reduced till lost, after an action force F of the tubular product  119  on the treading rod  111  is lost, the treading rod is pulled to the original position by the reset spring  110 , the angle measuring sensor  112  resends the signal to the controller  113 , which controls the motor  12  to stop rotating, and in this way, the tubular product  119  is prevented from being knotted. 
     As shown in  FIGS. 8 and 9 , the limiting device  19  comprises a guiding wheel  114  rotatably disposed on the top of the treating rod  111 , one side of the guiding wheel back onto the central rod  15  is provided with a blocking piece  115  fixedly connected on the treading rod  111 , and a gap allowing the tubular product to penetrate through is formed between the guiding wheel  114  and the blocking piece  115 . 
     As shown in  FIGS. 8 and 9 , the central rod  15  is detachably connected to a pressing disc  116 , the pressing disc  116  is opposite to the material disc  14  and can prevent the tubular product  119  from being separated out of the central rod  15  when the coil  118  rotates. 
     As shown in  FIG. 10 , the bottom plate  17  is provided with a spring fixing nail  117 , the revolution bottom plate  18  is correspondingly provided with another spring fixing nail  117 , and the two spring fixing nails  117  are mutually staggered, the reset spring  110  is a tension spring, and both ends of the tension spring are connected to a spring fixing nail  117  respectively. 
     The reset spring  110  can be restored to an initial state when the treading rod  111  loses the action force of the tubular product, such that the angle measuring sensor sends a signal to the controller  113 , the controller  113  controls the motor to stop rotating, and the tubular product is prevented from being charged without limitation to cause accumulation and deformation of the tubular product. 
     A specific working process of the unwinding mechanism is: when the subsequent machining device (the feeding and straightening device  2  in the present production line) pulls the tubular product  119  actively, the tension of the tubular product  119  is increased, a pull force F toward an advancing direction of the tubular product  119  is generated for the treading rod  111 , under the action of the pull force F, the treading rod  111  drives the revolution bottom plate  18  to swing to the advancing direction of the tubular product  119  gradually, the reset spring  110  is stretched, the angle measuring sensor  112  measures the swing angle and sends a signal to the controller  113 , when the swing angle reaches a preset starting value, the controller  113  starts the motor  12  which drives the speed reducer  13  to rotate, the speed reducer  13  drives the material disc  14  and the coil  18  on the material disc to rotate, the section of tubular product  119  between the coil  118  and the machining device is loosened, the tension of the tubular product  119  is reduced, the pull force F acting on the treading rod  111  is reduced therewith, under the pull force of the reset spring  110 , the treading rod  111  is gradually restored to the original position, the angle measuring sensor  112  measures the swing angle in real time and transmits to the controller  113 , and when the swing angle reaches a preset stop value, the controller  113  controls the motor  12  to stop rotation. 
     The treading rod  111  can realize swing, such that the tubular product  119  can be buffered when being actively pulled by the machining device, the treading rod  111  or treading rod  119  is prevented from damage due to a large stress, the angle measuring sensor  112  is used to measure the swing angle of the treading rod  111  in real time and control the motor, excessive loosing of the tubular product  119  is prevented, and the tubular product  119  is prevented from being knotted. 
     As shown in  FIGS. 4-6 , the feeding straightening device  2  comprises a rack  21 , the rack  21  is provided with two pairs of feeding wheels  22 , a straightening mechanism  23  and a length fixing mechanism  24  along a straight line in sequence, a wire passing base  25  is disposed at the front part of the feeding wheels  22 , between the two pairs of the feeding wheels  22  and between the feeding wheels  22  and the straightening mechanism  23  on the rack  21  respectively, the straightening mechanism  23  comprises a hollow shaft-like straightening component  231  rotatably disposed on the rack  21  and a straightening power system  232  driving the hollow shaft-like straightening component  231  to rotate, the hollow shaft-like straightening component  231  comprises a hollow left end shaft  233 , five straightening dies  234  and a hollow right end shaft  235 , the left end shaft  233  and the right end shaft  235  are rotatably disposed on the rack  21  respectively, a connecting block  236  with a material passing hole in the middle is disposed among the adjacent straightening dies  234 , the positions of the straightening dies  234  meet a condition that the central lines of all straightening dies  234  are in staggered arrangement relative to the axis of the left end shaft  233 , the straightening die  234  comprises two straightening modules provided with semicircular slots matched with the diameter of the tubular product to be straightened, connecting surfaces of the left end shaft  233 , the connecting blocks  236  and the right end shaft  235  matched with the straightening dies are provided a mounting groove matched with the shape of the straightening die  234  and an arc slot located for compressing compression bolts  237  of the straightening dies and internally provided with a plurality of threaded sections respectively, the length fixing mechanism  24  comprises a pair of measuring wheels  241  driven by the tubular product to rotate and placed on the rack  21 , and one of the measuring wheels  241  is connected to a revolution encoder  242 . 
     As shown in  FIG. 7 , the cutting-off mechanism  3  comprises a mounting base  31 , the mounting base  31  is provided with two upright plates  32  vertical to each other, one upright plate  32  is provided with a fixed shearing head  33 , the other upright plate  32  parallel with a feeding direction is provided with a shearing oil cylinder  34  and the end part of the piston rod of the shearing oil cylinder  34  is provided with a moving shearing head  35  matched with the fixed shearing head  33 . 
     As shown in  FIG. 3 , the material loading mechanism  5  comprises two end part mounting frames  51  disposed on two ends of the base of the bending and molding device respectively, the end part mounting frames  51  are provided with a transmission shaft  52  and a charging power device driving the transmission shaft  52 , the transmission shaft  52  is provided with at least two material holding arms  53  in parallel, the end part of each material holding arm  53  is provided with a pneumatic clamping component  54  which is controlled by a cylinder to open or clamp, the positions of the material holding arms  53  are matched with the positions where the cutting-off mechanism  3  and the central camping mechanism charge the tubular product. 
     As shown in  FIGS. 12-16 , the bending and molding device  4  comprises a base  41 , the base  41  is provided with a transverse sliding rail  42 , two transverse sliding bases  43  are disposed on the transverse sliding rail  42  in a sliding manner, and the base  41  is provided with a transverse driving device  44  driving the transverse driving bases  43 . The transverse driving device  44  comprises a rack disposed on the base  41 , the transverse sliding base  43  is provided with a transverse driving motor  441 , and an output shaft of the transverse driving motor  441  downwards penetrates out of the transverse sliding base  43  and is connected to a gear  442  matched with the rack thereon. The base  41  is provided with a central clamping device  45  which can clamp the tubular product and can rotate around a central axis of the tubular product between the two transverse sliding bases  43 . 
     The transverse sliding base  43  is provided with a longitudinal sliding rail  46 , the longitudinal sliding rail  46  is provided with a longitudinal sliding base  47  in a sliding manner, and the transverse sliding base  43  is provided with a longitudinal driving device  48  driving the longitudinal sliding bases  47  to slide. The longitudinal driving device  48  comprises a longitudinal driving motor  481  disposed on the transverse sliding base  43 , the longitudinal sliding base  47  is provided with a longitudinal lead screw  482 , and the longitudinal driving motor  481  is connected to the end part of the longitudinal lead screw  482  through a coupler  483 . The longitudinal sliding base  47  is provided with a bending and molding device  49 . 
     The bending and molding device  49  comprises a hollow mounting base  491  rotatably disposed on the longitudinal sliding base  47 , a hollow shaft  492  is rotatably disposed in the mounting base  491  in a penetrating manner, a mandrel  493  is rotatably disposed in the hollow shaft  492  in a penetrating manner, one end of the hollow shaft  492  and one end of the mandrel  493  extend out of the longitudinal sliding base  47 , the hollow shaft  492  is provided with a moving bending head  494  at this end, the end part of the moving bending head  494  is cylindrical and its periphery is provided with a circle of groove matched with the tubular product to be matched, the mandrel  493  is detachably provided with a bending die  495  at this end, the fixed bending die  495  is provided with four cylindrical fixed bending modules of which the connecting lines are in a rectangle, an interval between two rows of fixed bending modules is matched with a diameter of the tubular product to be bent, the other end of the mandrel  493  is connected to a fixed die motor  496  disposed on the longitudinal sliding base  47 , a driven synchronous bent wheel  497  sleeves the periphery of the other end of the hollow shaft  492 , the longitudinal sliding base  47  is provided with a moving die motor  498 , an output shaft of the moving die motor is provided with a driving synchronous belt wheel  499  matched with the driven synchronous belt wheel  497 , and a synchronous belt sleeves the driven synchronous belt wheel  497  and the driving synchronous belt wheel  499 . 
     One side, close to the central clamping device  45 , of the transverse sliding base  43  at the left side is provided with a left clamping device  410  capable of movably extending to clamp the tubular product. The left clamping device comprises a left base  4101  disposed on the longitudinal sliding base  47  at the left side, a certain included angle exists between the upper surface of the longitudinal sliding base and the left base, the upper surface of the left base  4101  is provided with a left sliding rail  4102 , the left sliding rail  4102  is provided with a left sliding base  4103 , the left sliding base  4103  is provided with a left mounting base  4104 , the left mounting base  4104  is provided with a clamping component  4105  driven by a clamping cylinder to open or clamp, and the left base  4101  is provided with a sliding cylinder  4106  driving the left sliding base  4103  to drive the clamping component  4105  to approach to the tubular product from bottom to top; 
     One side, close to the central clamping device  45 , of the transverse sliding base  43  at the right side is provided with a right clamping device  411  capable of movably extending to clamp the tubular product. The right clamping device comprises a right base  4111  disposed on the longitudinal sliding base  47  at the right side, a certain included angle exists between the upper surface of the longitudinal sliding base and the right base, the right base  4111  is provided with a right sliding rail  4112 , the right sliding rail  4112  is provided with a right sliding base  4113 , the right sliding base  4113  is provided with a right mounting base  4114 , the right mounting base  4114  is provided with a clamping component  4115  driven by a clamping cylinder to open or clamp, and the right base  4111  is provided with a sliding cylinder  4116  driving the right sliding base  4113  to drive the clamping component  4115  to approach to the tubular product from top to bottom. 
     A specific working process of the bending and molding device  4  is: when the material loading mechanism  5  places the well prepared tubular product onto the central clamping device  45 , the left and right transverse sliding bases move at the same time and begin to bend the tubular product from two ends to the middle section by section. 
     The moving process of the transverse sliding base  43  at the left side is described in detail, when the tubular product is placed on the central clamping device  45 , a signal receiver on the central clamping device  45  sends a signal to the controller, the controller drives the longitudinal driving motor  481  to rotate so as to drive the longitudinal lead screw  482  to rotate, and the longitudinal sliding base  47  is pushed to extend forwards to reach to a designated bending position. Meanwhile, the clamping component  4105  is pushed by the sliding cylinder  4106  to extend out and reach a corresponding position to clamp the tubular product. At this point, the transverse driving motor  441  rotates to drive the gear  442  and rack mechanism to move, and the transverse sliding bases  43  are transversely moved to the designated bending position. Bending is started, the moving die motor  498  drives the hollow shaft  492  to rotate, and the moving bending head  494  at the front end of the hollow shaft  492  rotates therewith to bend the tubular product. 
     When space bending is required, only the central clamping device  45  is required to rotate the tubular product by a corresponding angle, then the transverse driving motor  441  drives the transverse sliding base  43  to reach a corresponding bending section position, and further the tubular product is bent. 
     When a bending radius or a angle bending shape needs to be corrected or the raw material of the used tubular product is bent per se, and certain section, a certain angle is formed between which and the central clamping device  45 , on the tubular product needs to be bent, the longitudinal driving motor  481  rotates reversely, the longitudinal lead screw  482  rotates therewith and drives the longitudinal sliding base  47  to return, at this point, the fixed die motor  496  drives the mandrel  493  to rotate for a required angle, the fixed bending die  495  at the front end of the mandrel  493  rotates to a corresponding angle therewith, then the longitudinal driving motor  491  pushes the longitudinal slide base  47  to reach a bending position to locate a section to be bent between the two rows of fixed bending dies, and then the tubular product is bent to change the bending radius or the angle bending shape. 
     After the required bending action is finished, the clamping component  4105  is loosened and returned, meanwhile, the longitudinal driving motor  481  rotates backwards, the longitudinal lead screw  482  rotates and drives the longitudinal sliding base  47  to return back to the initial position, and then the transverse driving motor  441  drives the transverse sliding base  43  to retreat to the initial position. 
     If the diameter of the tubular product to be bent changes, then the fixed bending die  45  is directly replaced. 
     The central clamping device  45  as shown in  FIGS. 17-22  comprises a box body  71 , a rotary gear disk  72  rotatably disposed on the box body  71 , a power device  73  disposed on the box body  71 , a transmission mechanism  74  connected to the rotary gear disk  72  and the power device  73 , and a clamping mechanism  75  disposed on the rotary gear disk  72  for clamping the tubular product, wherein the transmission mechanism  74  comprises a main synchronous belt wheel  741  fixedly connected on an output shaft of the power device  73 , a left transition gear  744  and a right transition gear  745  which are meshed with the rotary gear disk  72  respectively, a left transmission gear  747  meshed with the left transition gear  744 , a right transmission gear  748  meshed with the right transmission gear  74 , a left synchronous belt wheel  742  coaxial and capable of synchronously rotating with the left transmission gear  747 , a right synchronous belt wheel  743  coaxial and capable of synchronously rotating with the right transmission gear  748  and a synchronous belt  746  connected to the main synchronous belt wheel  741 , the left synchronous belt wheel  742  and the right synchronous belt wheel  743 , the left transition gear  744  is connected on the box body  71  by a first transition shaft  79 , and the right transition gear  745  is connected on the box body  71  by a second transition shaft  710 . 
     The transmission mechanism  74  is driven by the synchronous belt  746 , has a buffering and damping action, stable transmission is realized by the meshing between the left transition gear  744  and the right transition gear  745  and the rotary gear disk  72 , the error of the rotary gear disk  72  generated in forward and backward rotation processes is eliminated, and the rotation precision is improved. 
     As shown in  FIGS. 17 and 18 , the clamping mechanism  75  comprises a left clamping block  751  and a right clamping block  752 ; the left clamping block  751  and the right clamping block  752  are respectively symmetrically connected to a disc surface of the rotary gear disk, the opposite sides of the left clamping block  751  and the right clamping block  752  are respectively provided with a left chuck  7511  and a right chuck  7521 , the lower part of the left clamping block  751  located on the left chuck  7511  is provided with a left pushing block  7512 , the lower part of the right clamping block  752  located on the right chuck  7521  is provided with a right pushing block  7522 , the sides, back onto each other, of the left clamping block  751  and the right clamping block  752  are connected to the rotary gear disk  72  by a left tension spring  753  and a right tension spring  754 , the left chuck  7511  and the right chuck  7521  are matched, the left tension spring  753 , a pull force of the left tension spring  753  and the right tension spring  754  drives the left chuck  7511  and the right chuck  7521  to abut against each other, the left pushing block  7512  and the right pushing block  7522  are mutually symmetric, a reset pushing rod  755  and a reset oil cylinder  756  driving the reset pushing rod  755  are disposed below the left pushing block  7512  and the right pushing block  7522 , the reset pushing rod  755  pushes the left pushing block  7512  and the right pushing block  7522  when upwards pushing, the left clamping block  751  and the right clamping block  752  are promoted to rotate, and the left chuck  7511  and the right chuck  7521  are promoted to be separated. 
     The clamping mechanism  75  adopts a spring self-clamping structure, and is simple in structure and stable in clamping force, the reset pushing rod  755  is pushed by a piston rod of the reset oil cylinder  756  to further open the clamping mechanism  75 , such that separation between power and the structure is realized, and the stability of the clamping mechanism  75  in the rotation process of the rotary gear disk  72  is ensured. 
     As shown in  FIG. 18 , abutting against each other, the left chuck  7511  and the right chuck  7521  form a ring containing the tubular product, the center of the ring and a rotation center of the rotary gear disk  73  are coincided, and a rotation precision of the tubular product is improved. 
     The power device  73  comprises a servomotor  731  and a right angle speed reducer  732  connected to the servomotor  731 , so not only is a rotary speed of the rotary gear disk  71  controlled, but also the rotation precision is further improved. 
     As shown in  FIGS. 17, 19 and 21 , the center clamping device also comprises a poking mechanism  76  for unloading, wherein the poking mechanism  76  comprises a main poking shaft  761  vertical to the rotary gear disk  72 , a poking transmission shaft  762  parallel with the main poking shaft  761  and fixedly connected on the box body  71 , and a poking gear shaft  763  parallel with the main poking shaft  761  and rotatably connected on the box body, the main poking shaft  761  is in rotary connection with the box body  71 , two ends of the main poking shaft  761  extend out of the box body  71  respectively and are connected to a poking arm  77  outside the box body  71  respectively, a main poking gear  764  is fixedly disposed on the main poking shaft  761  in the box body  71 , a slave poking gear  765  is rotatably disposed on the poking transmission shaft  762 , the poking gear shaft  763  is provided with a third poking gear  766 , the main poking gear  764  is meshed with the slave poking gear  765 , the salve poking gear  765  is meshed with the third poking gear  766 , the poking mechanism also comprises a poking cylinder  767  fixed in the box body and a rack  768 , the rack  768  is connected to the poking cylinder  767  and performs telescopic movement along with the poking cylinder  767 , the rack  768  is meshed with the poking gear shaft  763 , one side, back onto the poking gear shaft  763 , on the rack  768  is further provided with a rack compressing device  769  compressing the rack  768  on a poking driving gear on the poking gear shaft  763 ; and the box body  71  is further internally provided with a poking oil cylinder  78  capable of driving the reset pushing rod  755 . 
     The rack compressing device  769  as shown in  FIG. 22  comprises a compressing shaft  7691  fixedly connected on the box body  71  and an idler wheel  7692  rotatably connected on the compressing shaft  7691 , and the idler wheel  7692  abuts against the rack  768  and moves along a movement direction of the rack  768 . 
     By increasing the poking mechanism, automatic unloading is realized, the degree of automation is realized, and the labor cost is reduced; due to the rack compressing device  769 , the rack  768  can be accurately meshed with a poking driving gear on the poking gear shaft  763 , and the transmission stability of the rack is realized. 
     As shown in  FIG. 21 , the right transmission gear  748  rotatably sleeves the main poking shaft  761 , the right synchronous belt wheel  743  and the right transmission gear  748  are coaxial and are fixedly connected on the right synchronous belt wheel  743 , an inward internal space is saved and the manufacture cost is saved. 
     A specific working process of the central clamping device is: firstly, the rotary gear disk  72  is located in an initial position where the reset pushing rod  755  and the reset oil cylinder  756  are matched. Then the reset oil cylinder  756  is started, such that a push rod thereof pushes the reset pushing rod  755 , the reset pushing rod  755  is stressed to upward push the left pushing block  7512  and the right pushing block  7522 , and the clamping mechanism  75  is opened. After the tubular product is placed therein, the reset oil cylinder  756  is closed, the reset pushing rod  755  is retreated, the left clamping block  751  and the right clamping block  752  respectively rotate in an opposite direction under the action of a pull force of the left tension spring  753  and the right tension spring  754  till the left chuck  7511  and the right chuck  7521  clamp the tubular product, and the charging is ended. 
     In the bending process of the tubular product, the rotation of the rotary gear disk  72  is controlled by controlling the power device  73 . A specific transmission process is: the servomotor  731  drives the right angle speed reducer  732  to drive the main synchronous belt wheel  741  to rotate, the main synchronous belt wheel  741  drives the left synchronous belt wheel  742  and the right synchronous belt wheel  743  to rotate through the synchronous belt  746 , while the left transmission gear  747  and the left synchronous belt wheel  742  rotate synchronously, the right transmission gear  748  and the right synchronous belt wheel  743  rotate synchronously, the left transmission gear  747  drives the left transition gear  744  to rotate, the right transmission gear  748  drives the right transition gear  745  to rotate, and the left transition gear  744  and the right transition gear  745  drive the rotary gear disk  72  to rotate together such that the tubular product rotates to a required angle. 
     After the tubular product bending machine bends the tubular product, under the drive of the power device  73 , the rotary gear disk  72  rotates to a position where the reset pushing rod  755  and the poking oil cylinder  78  are matched, then the poking oil cylinder  78  is started to push the reset pushing rod  755  out to open the clamping mechanism  75 , afterwards, the poking cylinder  767  drives the rack  768  to move, the rack  768  transmits power to the poking gear shaft  763  meshed with the rack, the third poking gear  766  disposed on the poking gear shaft  763  drives the slave poking gear  765 , the slave poking gear  765  drives the main poking gear  764 , the main poking gear  764  drives the main poking shaft  761  to rotate to drive the poking arms  77  on two ends of the main poking shaft  761  to rotate, and the poking arms  77  rotate to finally push the tubular product to be separated from the clamping mechanism  75  and the rotary gear disk  72 . Then the poking oil cylinder  78  is closed, such that the clamping mechanism  75  restores to be clamped, the power device  73  is started, and the rotary gear disk  72  is driven to rotate to the initial position, and the unloading is finished. 
     A wire trimming process is described briefly, specifically, the four feeding wheels  22  in the feeding straightening device  2  are controlled by the a wire trimming control system to be meshed with the tubular product to be conveyed forward, the treading rod  111  in the tubular product pulling unwinding mechanism  1  drives the revolution bottom plate  18  to rotate for certain angle α, the angle measuring sensor  112  sends a signal to the wire trimming control system, the wire trimming control system compares it with a set angle β, if β is larger than α, then the angle measuring sensor  112  detects again, and if β is smaller than α, then the wire trimming control system sends a signal to the motor  12  to send a signal so as to drive the material disk  14  to feed the materials forwards. The feeding wheels  22  of the feeding straightening device  2  are meshed with the tubular product to convey it to the straightening component  231 , the straightening power system  232  drives the straightening component  231  in the straightening mechanism  230  to rotate, and the five pairs of straightening modules in the straightening component  231  rotate to straighten the tubular product. 
     When conveyed, the tubular product straightened by the straightening component  231  penetrates through the length fixed mechanism  24  and the cutting-off mechanism  3  in sequence and moves to a position above the material holding arms of the material loading mechanism. When the tubular product is conveyed out, the measuring wheels  241  in the length fixing mechanism  24  are driven to rotate, the revolution encoder  242  connected to the measuring wheels  241  monitors a tubular product passing length L 1  converted from a rotary angle of the measuring wheels  241  in real time and sends a signal to the wire trimming control system, the wire trimming control system compares the measured tubular product length L 1  with a set value L, and till L 1  equals to L, the wire trimming control system sends the signal to the feeding wheels  22  of the feeding straightening device  2  to stop rotation, at this point, the treading rod  111  rotates for certain angle, and when an included angle α the angle measuring sensor  112  is smaller than a set value α in the wire trimming control system, the wire trimming control system sends a signal to the motor  12  in the unwinding mechanism  1  to control the material disc to stop rotation and feeding. At this point, if the bending and molding device  4  has been in an idle state, then the wire trimming control system controls the material holding arms  53  in the material loading mechanism  5  to clamp the tubular product, and then a shearing oil cylinder  34  in the cutting-off mechanism  3  extends to cut off the tubular product. 
     Then, the transmission shaft  52  drives the material holding arms  53  to overturn by a certain angle to feed the tubular product to the central clamping mechanism  45 , and the clamping mechanism  75  in the rotary gear disk  72  clamps the tubular product. Then, the material loading mechanism  5  is reset to one side of the cutting-off mechanism to wait for the next charging period, at this point, the unwinding mechanism  1  and the feeding straightening device  2  enter the next feeding straightening period, and the bending and molding device  4  bends and molds the tubular product. 
     After the tubular product bending machine bends the tubular product, under driving of the power device, the rotary gear disk  72  of the central clamping device  45  rotates to a position where the reset pushing rod  755  and the poking oil cylinder  78  are matched, then the poking oil cylinder  78  is started to open the clamping mechanism  75 , then the poking cylinder  767  drives the poking arms  77  disposed on two ends of the poking cylinder to rotate, the poking arms  77  rotate and finally push the tubular product to be separated from the clamping mechanism  75  and the rotary gear disk  72 , then the poking oil cylinder  78  is closed, such that the clamping mechanism restores the clamping, the power device  73  is started, the rotary gear disk  72  is driven to rotate to the initial position, and unloading is finished. 
     The above embodiments merely exemplarily illustrate the principle and effects of the present invention and are merely partially applied embodiments instead of limiting the present invention; it should be pointed out that those skilled in the art can make some transformations and improvements without departing from creative thought of the present invention, and those transformations and improvements all belong to a protective scope of the present invention.