SPECIFICATIONBending ApparatusBackground of the Invention 1. Field of the InventionThis invention relates to apparatus for bending bar-shaped, plastically-workable materials such as metal rods and pipes.
2. Description of the Prior ArtHeretobefore the operation of bending barshaped materials has been made manually with the help of a pair of spaced-apart studs projecting from a base plate. That is, one end of the material is positioned between the studs, and its other end is manually turned about the studs to bend the material. Among the problems of such a conventional technique is that the material often cannot be bent in exact accordance with the predetermined radius of curvature or at the exact predetermined position.
In order to solve such prior art problems has been proposed a bending apparatus wherein a bender means is coupled to a rotatable shaft having a sprocket. A chain is fitted on to the sprocket and an output shaft of a geared motor.
The bender means has a circular shape, and a material to be bent is pressed against the periphery thereof with a suitable clamp means and the shaft is rotated to bend the material along said periphery. In such a proposal, however, if a large-sized sprocket is used, the forward portion of the work that moves as the bender means is rotated (portion of the work that is forward of its portion held by the presser means and clamp means) may strike against the sprocket to prevent the bending operation. Such a situation is often encountered where a bar-shaped material is to be successively bent at a number of sections thereof in its lengthwise direction. An attempt at removing such a drawback may be made by employing a sprocket of smaller diameter.In that case, however, a greater amount of power is required for the bending operation, calling for the use of a motor with a larger capacity, for example.
Summary of the InventionThe present invention aims to obviate these prior art problems.
According to the invention, a material to be bent is tightly held, at a portion thereof, by and between the periphery of a circular work support and a clamp means and a bending operation is made by moving the work support and the clamp means about a shaft supporting the work support so that the material is bent by and along the periphery or bending surface of the work support so as to be given exactly the same curvature as the bending surface thereof.
According to another aspect of the invention, a bar-shaped material can be successively bent at a number of portions thereof in the abovementioned manner, without encountering anv difficulty, even if the distances between theportions to be bent are relatively small, so that thematerial may be bent in a delicately skillfulmanner.
The foregoing second advantages of the invention is obtained by using the followingconstruction: A bender arm is pivotally connected to the above-mentioned shaft, and said clampmeans is located in conjunction with the benderarm. Before starting the bending operation, thebender arm is positioned at practically right anglesto the direction in which to feed the material, sothat the entire space in front of the bendingmechanism (comprising the work support andbender arm), namely, that into which each portionof the material to be bent will project, may bemade free from any obstruction that wouldprevent the bending operation. In addition, during -bending operation, the free space may be utilizedto allow the bent portion of the material to movefreely therein.Therefore, the successive operationof bending a bar-shaped material at a number ofportions thereof may be made, regardless of howlong its portions between those to be bent is,while allowing the already-bent portion orportions to move freely in said space. Thus, nodifficulty is encountered in bending the differentportions of the material exactly along the bendingsurface of the work support.
Still further feature of the invention is that thebender arm is provided with a driven point forreceiving a force to operate the arm. This enablesthe driven point of the arm to be located at arelatively long distance from said shaft while atthe same time keeping intact the abovementioned free large space in front of the bendingmechanism. When the driven point of the arm islocated at such a distance, the driven point is onlyrequired to receive a relatively smaller force forthe bending operation.
Other objects and advantages of the inventionwill become apparent during the followingdiscussion of the accompanying drawings.
Brief Description of the DrawingsFig. 1 is a partly-broken perspective view of abending apparatus according to the inventionwhich illustrates a bending mechanism thereofprepared for bending operation;Fig. 2 is a partly section plan view of a portionof a bender arm employed in the apparatus of Fig.
1;Fig. 3 illustrates the apparatus of Fig. 1 inbending operation;Fig. 4 is a plan view of a drive mechanismemployed in the apparatus of Fig. 1 which showsthe drive mechanism when the apparatus is in thecondition of Fig. 1;Fig. 5 is a plan view of the drive mechanismwhen the apparatus is in the condition of Fig. 3;Fig. 6 is a perspective view of another form ofdrive mechanism which may be employed in theapparatus;Figs. 7 and 8 are plan views of the drivemechanism of Fig. 6 similar to Figs. 4 and 5; andFig. 9 illustrates how the apparatus herein is operated if a link shown the foregoing various figures is not employed.
Detailed Description of the Preferred EmbodimentReferring now to the drawings, and to Fig. 1 in particular, a bending apparatus according to the invention includes a frame 1 having a pair of rails 2 on its upper surface which extend in the lengthwise direction of the apparatus. On the rails 2 is located a carriage means 4 which is provided with wheels 5 to allow the carriage 4 to move along the rails 2 and to which is coupled a chuck 3 to hold a work W. The carriage means 4 is adapted to travel automatically, as required, by means of an advance mechanism (not shown).
Also, the carriage means 4 is provided with a built-in chuck rotator (not shown) which serves to turn the work Wheld by the chuck 3. Although the work Wto be bent by the apparatus is illustrated in the form of a round bar in the drawings, bar-shaped materials with different cross sections may be bent thereby. Numeral 6 designates a block support secured to the forward end of the frame 1 and provided with a pair of shaft supports 7 at the leftmost end (as viewed from the front of the apparatus) of the front side of the block support 6. Also on the front side of the block support 6 is formed a trapezoid-shaped block guide 8 which extends crosswise of the rail direction. A shaft 10 is rotatably connected to and supported by the supports 7 of the block support 6 (through bearings, not shown). A block 11 is dovetailed with the guide section 8 of the support 6.The block 11 is slidable a!ong the guide section 8, i.e. adapted to be moved therealong over a certain distance by a hydraulic cylinder (not shown) built into the block support 6. A shaft 12 is fixedly mounted to the slidable block 11, and a circular presser means 13 is rotatably coupled to the fixed shaft 12. The presser means 13 is recessed at its periphery to provide a curved surface to press against the periphery of the workW. Also, the presser means can be removed from the shaft 12 so as to replace it with another one of desired outside diameter.
A circular work support 9 is coupled to the rotatable shaft 10. The work support 9 has a radius of curvature R and also is recessed at its periphery so as to provide a curved support or bending surface 9a to virtually conform to the periphery of the work W. The work support 9 can also be removed from the shaft 10 to replace it with another one of desired radius of curvature or curved surface 9a. In front of the block 1 1 is located a bender arm 14 shaped similarly to the block support 6 and having a pair of shaft supports 15 connected to the shaft 10. As with the block support 6, the bender arm 14 is provided with a trapezoid-shaped block guide 16 at its front side which projects forward therefrom and extends substantially radially relative to the shaft 10. A block 17, similar to the preceding one 11, is dovetailed with the guide section 1 6 of the bender arm 14.As with the block 1 the block 17 is slidable along the guide section 16, i.e.
adapted to be moved therealong over a certain distance by a hydraulic cylinder 82 (Fig. 2) built into the bender arm 14. As shown in Fig. 2, the bender arm 14 is provided with a recess 81 in which the cylinder 82 having a piston rod 83 is located with its body secured to the inner surface of the arm 14. The block 1 7 projects into the recess 81 at 84, and one end of the piston rod 83 is connected to the projection 84. Thus, the block17 can be moved along the guide section 16 in indicated directions by operating the piston rod 83. The sliding of the block 11 along its support 6 is allowed by a similar mechanism. Referring again to Fig. 1, a clamp means 19 is bolted to the slidable block 17 at 18.The clamp means 19 is recessed at one side thereof so as to provide a curved surface corresponding to the curved bending surface 9a of the work support 9, thereby enabling the clamp means 19 to hold the work W tightly together with the work support 9. Numeral 21 designates a drive link which is pivotably connected, at its one end, to the bender arm 14 by means of a drive pin 22.
If the work Wto be bent hereby has a cross section other than a circle, the presser means 13, work support 9, and clamp means 19 may be all replaced with those contoured to fit such a different work.
Numeral 23 designates a mechanism connected to the drive link 21 for imparting a bending force to the driven point of the arm 14, i.e., drive pin 22, through the link 21. This drive mechanism 23 includes components designated by numerals 24 to 46: A drive motor 24 has a driving shaft 25 and a control shaft 27 which are provided with a sprocket 26 and a belt pulley 28, respectively. The control shaft 27 is adapted to adjust the rotation amount of the drive motor 24.
The drive motor 24 is connected to a bendingoperation control motor 46 by means of a belt 30 which is fitted onto the pulley 28 of the motor 24 and the pulley 29 of the control motor 46. A computer-controlled pulse motor is preferably used as the control motor 46 in order to achieve a higher degree of control accuracy. Numerals 31 and 32 designate shafts which are rotatably supported by bearings 33 and 34, respectively. A sprocket 35 is coupled to the shaft 31, and a chain 36 is fitted onto the sprockets 35 and 26.
Disks 39 and 40 are securely fastened to the upper ends of the rotatable shafts 31 and 32, respectively. First crankpins 37 and 38 are mounted on the disks 39 and 40, respectively, in eccentric positions relative to those disks, and are also connected to the middle and rear portions, respectively, of the drive link 21.The crankpins 37 and 38 are located relative to the shafts 31 and 32, respectively, in such a manner that the positional relationships between pin 37 and shaft 31 and between pin 38 and shaft 32 are at all times exactly the same as that between drive pin 22 and shaft 10; to be more precise, as best illustrated in Figs. 4 and 5, not only the imaginary horizontal lines connecting the axes of the pin 37 and the shaft 31 and those of the pin 38 and the shaft 32 are always parallel with that connecting the axes of the drive pin 22 and shaft 10, but also the crankpins 37, 38 are located at the same distances from the shafts 31, 32, respectively, as the drive pin 22 is spaced apart from the shaft 10.
Numerals 43 and 44 designate disks fastened securely to the lower ends of the rotatable shafts 31 and 32, respectively. Second crankpins 41 and 42 are mounted on the disks 43 and 44, respectively, in eccentric positions relative to those disks. The positional relationship between the lower crankpin 41 and the upper one 37 relative to the shaft 31 is such that the two pins 41 and 37 are located 90 degrees spaced apart from each other. Also, the positional relationship between the crankpins 42 and 38 (relative to the shaft 32) is the same as above mentioned. In addition, the distance between pin 41 and shaft 31 is the same as that between pin 42 and shaft 32. The crankpins 41 and 42 are connected to each other by means of an interlock link 45. It may be readily seen that the link 45 as well as disks 43 and 44 is rotated when the shafts 31 and 32 are rotated.
In operation, the work Wis bent to the radius of curvature R, as follows: First, the slidable blocks 11 and 17 are retracted, i.e. positioned away from the work support 9. In this condition, the work is positioned between the work support 9 and the clamp means 19 and held with the chuck 3 at its one end. Then the chuck carriage 4 is manually or automatically moved such a distance that one end of the portion of the work to be bent is exactly located between the work support 9 and the clamp means 19. This Is followed by sliding the blocks 11 and 17 towards the work so as to press the presser means 13 and the clamp means 19 against the work and so that the work is tightly held by the work support 9 and the clamp means 19, both having the recessed peripheries to closely fit the periphery of the work.
In this condition (Fig. 1), the control motor 46 is operated according to the desired bending amount of the work so as to determine the amount of rotation of the drive motor 24. Then the drive motor 24 is rotated to cause the shaft 31 to rotate, through the sprocket 26, chain 36, and sprocket 35, in a direction indicated by arrow of Fig. 1, so that the crankpins 37 and 41 are rotated in the same direction by the angles determined by said predetermined amount.
Simultaneously this operation rotates the crankpins 38 and 42, associated with the shaft 32, through the drive link 21 and the link 45 in the same direction and by the same angle as the crankpins 37 and 41. Thus, the drive link 21 makes an arcing motion, without changing its direction, with the distance between the shaft 31 and the crankpin 37 and that between the shaft 32 and the crankpin 38 as reference radii of the motion, so that the drive pin 22 is caused to move around the shaft 10 so as to turn the bender arm 14 in a pivotal manner by the angle determined by said predetermined amount of rotation of the drive motor 24 (Fig. 3). By this operation, the clamp means 19 and the work support 9 are turned and rotated, respectively, in the direction indicated by arrow of Fig. 3, while holding the work tightly.When the clamp means 19 and work support 9 are thus operated, the work is accordingly moved forward (as indicated in Fig. 3) (with the chuck carriage 4 moved forward along the rails 2) and the portion of the work immediately backward of its portion held by the clamp means 19 and support 9 is bent by the bending surface 9a of the support 9 while being supported thereby.
The foregoing bending operation may be started from the condition shown in Fig. 4, in which the imaginary horizontal line 1, connecting the axes of the shafts 31 and 32 makes approximately right angles with that 12 connecting the axes of the shaft 31 and crankpin 37 and that 13 connecting the axes of the shaft 32 and crankpin 38. In such an operation, when the shafts 31 and 32 have been rotated approximately 90 degrees, all foregoing lines 11,12, and 13 are brought into one straight line as illustrated in Fig. 5. Simultaneously, however, the pin 22 is subjected to a reaction F in a direction indicated by an arrow of Fig. 5, which reaction has been induced by the resistance of the work to the bending operation.This reactive force F is transmitted to the crankpin 38 by the action of the link 21, pivotably connected to the crankpin 37, as a lever, so that a force F' is exerted to the crankpin 38. The resultant force F' would raise the following problem without the link 45: For the accurate operation of bending the material, the crankpins 37, 38 and the drive pin 22 all must be turned by the same angles determined by the rotation of the shaft 31.If no link such as 45 were provided, however, the rotation of the shaft 31 for the purpose of turning all these pins by the same angle, such as one indicated by 6i in Fig. 9, would result in only the crankpin 37 being moved by that angle, but the other two pins 38 and 22 being turned to unexpected positions, such as those indicated by angles 2 and Q, respectively (Fig. 9).
The reason for this is that the foregoing reactive force F pushes the drive pin 22 back to the smaller-angle (03) position and the foregoing resultant force F' turns the crankpin 38 to the greater-angle ( 2) position because the crankpin 38 itself cannot resist the resultant force F' (as exerted in indicated direction of Fig. 9). That is, the crankpin 38 cannot prevent the drive pin 22 from being pushed back by the reactive force F.
Thus, when the shaft 31 is rotated a desired angle, the bender arm 14 is turned by a different angle so that the material Wcannot be bent at the required angle, i.e. the same one as the rotation angle of the shaft 31. However, since the embodiment herein of the invention is provided with the link 45, such a problem is not raised, but the work can be bent by the exact angle as predetermined.That is, the force F' will further rotate the shaft 32 clockwise independently of the shaft 31, but without success because of the following mechanism: That is, the foregoing imaginary horizontal line í, connecting the axes of the shafts 31 and 32 also makes, in the condition of Fig. 5, approximately right angles with the line 14 connecting the axes of the shaft 31 and pin 41 and the line 15 connecting the axes of the shaft 32 and pin 42. In addition, the crankpins 41 and 42 are connected to each other by the link 45. Thus, the further rotation of the shaft 32 by the resultant force F' is prevented by the link 45, so that the shafts 31 and 32 are never allowed to rotate except at exactly the same angles.
Therefore, the bender arm 14 connected to the drive link 21 is allowed to turn by the exact predetermined angle, i.e. the same one as the rotation angle of the shaft 31 , thereby bending the work at that exact angle.
The above-mentioned construction of bending apparatus may be modified by directly connecting the shaft 10 to the shaft support 7 of the block support 6 and rotatably connecting the work support 9 and bender arm 14 to the shaft 10.
Also, the crank pins 37, 41 and 38, 42 may be located in such positions that the pins 37 and 41 make any angle other than 90 degrees (and excepting around 0 and 180 degrees) relative to the shaft 31 and the pins 38 and 42 also make any angle other than 90 degrees (and excepting around 0 and 180 degrees) relative to the shaft 32, provided that such other angles made by the pins 37, 41 and by the pins 38, 42 must be the same as each other.
Referring to Figs. 6, 7, and 8, the bending apparatus herein may be operated by using a drive mechanism 51 instead of 23 shown in Figs.
1 to 5. In the embodiment of Figs. 6 to 8, the details of construction other than the drive mechanism 51 are fundamentally the same as the preceding embodiment, and the similar parts are designated by the same reference numerals. The drive mechanism 51 is so constructed as to function in the same way as the preceding one 23. That is, the drive mechanism 51 is adapted to move the link 21 in such a manner that the link 21 traces circular arcs with the distance between the axes of the drive pin 22 (point of the link 21 connected to the arm 14) and of the shaft 10 as a reference radius, and is adapted to keep the link 21 in its given direction wherever the link 21 is located during arcing motion.These functions of the drive mechanism 51 are enabled by the following construction: The drive mechanism 51 includes components designated by numerals 52 to 72 (Fig. 6). Numeral 52 designates a hydraulic drive cylinder having a piston rod 53. A drive rack 55 is connected, at its one end, to the rod 53 by means of a fastener 54. As with the preceding embodiment, shafts 56 and 57 are rotatably supported by bearings 56a and 57a, respectively, and disks 60 and 61 are coupled to the upper ends of the shafts 56 and 57, respectively.
Crankpins 58 and 59 are mounted on the disks 60 and 61, respectively, in eccentric positions relative to those disks. The positional relationships between shaft 56 and pin 58 and between shaft 57 and pin 59 are the same as those between shaft 31 and pin 37 and between shaft 32 and pin 38, respectively, of the preceding embodiment. The crankpins 58 and 59 are rotatably connected to the middle and rear portions, respectively, of the drive link 21. Gears 62 and 63 of the same sizes are secured to the lower ends of the crankshafts 56 and 57, respectively. The gears 62 and 63 are meshed with the forward end and rear portion, respectively, of the drive rack 55.Along the rack 55 is disposed a means 64 for controlling the backlash between the gears 62, 63 and the rack 55, which means 64 includes a pair of adjusters 64a, 64a located opposite to the gears 62, 63, respectively, with the rack 55 therebetween.
Since the adjusters 64a, 64a have exactly the same constructions and functions, only one of them (right-hand one in Fig. 6) will now be described. Numeral 71 designates a bearing secured to a frame (not shown) and rotatably supporting a shaft 68. The bearing 71 has a screw 71 a to enable the shaft 68 to be fixed to the bearing 71 for the purpose of making the shaft 68 unrotatable. A shaft 69 is connected to the upper end of the shaft 68, being located eccentric to the shaft 68 by an amount e. A roller 66 is rotatably coupled to the shaft 69, making contact with one side of the rack 55. Each adjuster 64a has such a construction.It may be seen that the rollers 65, 66 are moved towards or away from the gears 62, 63, respectively, by rotating the shafts 67, 68, so as to press the rack 55 against the gears 62, 63. Therefore, when an excessive backlash is produced between the gears 62, 63 and the rack 55, the shafts 67, 68 may be rotated by such an angle as required to remove the excess, so that the gears 62, 63 are normally meshed with the rack 55. And when the rack 55 has thus been displaced to such a position as to normally reengage with the rack 55, the rack 55 can be kept in that position by screwing at 70a, 71 a to make the shafts 67, 68 unrotatable. Numeral 72 designates a guide means attached to the upper surface of the rack 55 and partly contacting the upper surfaces of the gears 62, 63.
Instead of such a backlash controller 64 of an eccentric-shaft type, any other suitable type of means may be used to achieve the same purpose.
For example, a belt-shaped means adjustable in its position may be so located as to contact the rack 55 for the purpose of displacing the rack 55 by inches.
In operation, with a work held by the work support and the clamp means, the drive cylinder 52 is operated to advance the piston rod 53 and therefore the drive rack 55 by such an amount as required for the particular bending operation, so that the gears 62, 63 engaging with the rack 55 are rotated in the same directions and by the same angles as indicted by arrows. By this operation, the shafts 56, 57 are rotated to rotate the crankpins 58, 59 simultaneously in the same directions and by the same angles. Thus, the drive link 21 is caused to make an arcing motion, thereby turning the bender arm 14 through the drive pin 22 at the predetermined angle, so that the work is bent to the predetermined radius of curvature and angle.
If the foregoing bending operation is started from the condition of Fig. 7, the condition of Fig. 8 is produced when the operation has been made up to 90 degrees (same condition as Fig. 5). In this condition, however, since the gear 63 associated with the shaft 57 is engaged with the rack 55, the previously-mentioned force F' (referred to in connection with the first embodiment) cannot further rotate the shaft 57 clockwise independently of the other shaft 56. It is to be noted, in addition, that the prevention of further rotation of the shaft 57 can be made with a higher degree of reliability as the backlash or play between the gear 63 and the rack 55 is kept to the smallest degree required. Thus, the shafts 56 and 57 are allowed to rotate in an exactly simultaneous or integral manner, so that the bender arm 14 is turned strictly as predetermined, thus bending the work to the exact predetermined angle.
As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.