Abstract:
A bending apparatus for a long material comprises: supporting device for supporting a long material in cantilever fashion at least in a bending direction; bending device which nips the material at an input point apart from the supporting device and is rotated by a predetermined angle so as to bend the material between the supporting device and the input point; driving device for rotating the bending device; feeding device for moving the material toward the bending device and setting a position of the material; and moving device which sets up a separation distance between the supporting device and the bending device prior to bending of the material and allows the supporting device and the bending device to move relatively during the bending of the material.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a bending apparatus for a long material such as round bars and pipes, and more particularly to technology which enables cold bending of the long material at an arbitrary bending radius without use of any special bending die for hot processing.  
           [0003]    2. Description of the Related Art  
           [0004]    As an apparatus for bending a long material such as a hollow bar and solid round bar, there is a CNC bender which executes cold bending. Generally, the CNC bender comprises a carriage for moving such a material in the longitudinal direction and positioning it by gripping a rear end thereof, a bending die in which a groove having a slightly larger bending radius than the material is formed in the outer periphery and a clamp having a groove similar to the bending die and holding the material in cooperation with the bending die. In this CNC bender, by moving the clamp along the outer periphery of the bending die, the material is drawn into the groove and bent. Next, the carriage is forwarded and by rotating the material as required, next bending operation is carried out.  
           [0005]    Because in the aforementioned CNC bender, the bending radius of the material is determined by the bending radius of the bending die, the kinds of the bending radii are restricted. Further, because a head portion comprised of the bending die, the clamp and the like is large, a trace of a bent material may interfere with the head portion or other attached equipment, thereby possibly restricting a bending processing shape.  
           [0006]    Because the CNC bender has the above-described restriction, hot-bending by use of a dedicated total bending die for each product is a main stream for, for example, a solid stabilizer. However, the dedicated total bending die is quite expensive and production cost is relatively high if a bending die is prepared for even a product having a small production amount. Further, because spare parts need to be supplied still even after production thereof is stopped, its special bending die needs to be stored for a long period, so that a large amount of space is required. Further, in case of producing a prototype which cannot be cold-processed with the CNC bender, a skilled worker corresponds to this demand by partially heating the material and manually bending it. Therefore, there is such a problem that due date required by a customer cannot be satisfied sufficiently.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, an object of the present invention is to provide a bending apparatus for a long material capable of cold-bending material at an arbitrary curvature radius and bending angle without using any special bending die.  
           [0008]    To achieve the above object, the present invention provides a bending apparatus for a long material comprising: supporting device for supporting a long material in cantilever fashion at least in a bending direction; bending device which nips the material at an input point apart from the supporting device and is rotated by a predetermined angle so as to bend the material between the supporting device and the input point; driving device for rotating the bending device; feeding device for moving the material toward the bending device and setting a position of the material; and moving device which sets up a separation distance between the supporting device and the bending device prior to bending of the material and allows the supporting device and the bending device to move relatively during the bending of the material.  
           [0009]    The operation of the present invention will be described with reference to FIGS. 1, 2. If the bending device  2  is rotated by an angle φ at an input point B, a uniform moment is applied to the material W supported by the supporting device  1  between the input point B and a supporting point A, so that the material W is bent by the angle φ with a predetermined curvature radius. In this case, the curvature radius of the material W can be set up by setting a separation distance S between the input point B and the supporting point A appropriately. That is to say, according to the present invention, the material W can be bent at an arbitrary curvature radius and bending angle without using any special bending die. Further, by rotating the bending device in a direction opposite to that shown in FIG. 1, the material can be bent inversely, thereby making it possible to prevent an interference between the material W and the bending apparatus or other attached equipment.  
           [0010]    After bending processing at one position is finished, the material W is fed toward the bending device by the feeding device and next bending is started. At this time, the moving device moves any one or both of the supporting device  1  and the bending device  2  so as to set up a separation distance S. FIG. 1 shows an example in which the supporting device is fixed on an apparatus main body while the moving device  3  moves the bending device. In this case, the moving device  3  is an arm which is movable in the lateral direction in the FIG. 1 with respect to the supporting device  1  and rotatable around an end portion opposite to the bending device  2 .  
           [0011]    [0011]FIG. 2 shows an example in which the bending device  2  is fixed on the apparatus main body while the moving device is capable of moving the supporting device  1 . The moving device  3  is an arm which can approach or leave the bending device  2  and is rotated around an end portion opposite to the bending device  2 . With such a structure, when the bending device  2  is rotated, the moving device  3  is moved following the bending of the material W.  
           [0012]    In FIG. 1, the moving device  3  can be provided with driving device. For example, by disposing hydraulic cylinders on both sides of the moving device  3  and coupling a piston of the hydraulic cylinder to an outer periphery of the bending device  2  according to an appropriate method, reciprocating motion of the piston can be converted to a rotating motion of the bending device  2 . Alternatively, it is permissible to provide the moving device  3  with a rotation driving mechanism such as a hydraulic motor and further provide this rotation driving mechanism with the bending device  2 . However, in this case, a reaction force of moment applied to the bending device  2  is applied to a rotation center P of the moving device  3 . Consequently, an additional moment is applied to the material W so that the bending radius is not uniform at respective points of the material. This additional moment in FIG. 1 is analyzed as follows.  
           [0013]    Assume that a reaction force applied to the rotation center P of the moving device  3  in FIG. 3 is F and moment given to the material W by the bending device is M w . This moment M w  is a moment acting equally on respective points of the material. About balance of moment around the point B, which is applied to the moving device in FIG. 3, the following formula is established.  
             F*L   1   =M    (1)  
           [0014]    About balance of moment around the point B acting on the material, the following formula is established.  
             F*L   2   +M   w   =M    (2)  
           [0015]    Here, M in the formula indicates a decay moment inherent of the material and is provided schematically with the following formula.  
             M=d   3 *σ/6   (3)  
           [0016]    d: material diameter  
           [0017]    σ: stress at yield  
           [0018]    According to the formula (2), moment of F*L 2  as well as moment M w  by the bending device is applied to the material. If the length L 1  of the moving device is set long, according to the formula (1), F decreases inversely proportionally. Thus, the term of F*L 2  in the formula (2) decreases. Therefore, by prolonging the length of the moving device sufficiently, moment applied to the material is substantially equalized, thereby making the bending radius substantially uniform.  
           [0019]    When the driving device for rotating the bending device  2  is separated dynamically from the moving device  3 , F equals 0 in the formulas (1) and (2), and M w  equals M. That is, it is preferable since the moment in overall the bending area S is uniform. For example, in the example shown in FIG. 1, it is permissible to fix the driving device to the apparatus main body and couple the driving device with the bending device  2  by device of a joint such as universal joint. In contrast, when the example shown in FIG. 2 is dynamically analyzed, although the moment in overall the bending area S cannot be completely uniform, but can be approximately uniform by setting up the length L 1  of the moving device sufficiently large. Therefore, in this case also, it is desirable to set up the length of the moving device sufficiently large.  
           [0020]    Preferably, any one or both of the supporting device and the bending device has gripping device for gripping detachably the material with inner peripheral faces thereof having a configuration fitting to outer peripheral faces of the material. With such a structure, it is possible to suppress flattening or occurrence of pressure mark which may occur when the material is bent. Further, preferably, the feeding device includes rotating device for rotating the material around its axis in the longitudinal direction and setting an angular position. By rotating the material while feeding it, a three-dimensional product can be processed. Meanwhile, although the present invention is suitable for cold bending processing of a solid stabilizer, the present invention is not restricted to the manufacturing of such a product. Further, the material for use is not restricted to a round bar, but may be applied to material having an arbitrary cross section such as H-shaped channel and C-shape/L-shaped channel. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a plan view showing a condition in which material is being bent for explaining operation of the present invention;  
         [0022]    [0022]FIG. 2A is a plan view showing a condition in which material is being bent for explaining operation of the present invention, while FIG. 2B is a plan view showing a condition in which material has been bent from the condition shown in (A);  
         [0023]    [0023]FIG. 3 is a plan view showing a bending apparatus according to the first embodiment of the present invention;  
         [0024]    [0024]FIG. 4 is a side view showing a bending apparatus of the first embodiment of the present invention;  
         [0025]    [0025]FIG. 5 is a plan view showing a bending apparatus of the first embodiment of the present invention;  
         [0026]    [0026]FIG. 6 is a plan view showing a bending apparatus of a second embodiment; and  
         [0027]    [0027]FIG. 7 is a side view showing a bending apparatus of the second embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    1. First embodiment  
         [0029]    A. Structure of the first embodiment  
         [0030]    Hereinafter, the preferred embodiments of the present invention will be described with reference to FIGS. 4, 5. The bending apparatus of this embodiment comprises an arm positioning mechanism (moving device)  20 , a material feeding mechanism (feeding device)  40  and a bending head portion (bending device)  60 , these components being mounted on a frame  10 . The structure of these components will be described below. Reference numeral  21  in the Figure indicates a guide rail and a slide frame  22  is supported slidably in the lateral direction in FIG. 4. A motor  23  is provided on the frame  10  with its output shaft  23   a  directed horizontally. An end portion of a ball screw  24  is coupled to an output shaft  23   a  of the motor  23  while the other end portion of the ball screw  24  is supported rotatably by a bearing  25  mounted on the frame  10 .  
         [0031]    Reference numeral  27  in the same Figure denotes a movable stopper, which is supported slidably by a guide rail  21 . A ball screw (female screw) is provided in the movable stopper  27  such that it engages a ball screw  24 . If the ball screw  24  rotates, the movable stopper  27  is reciprocated linearly along the guide rail  21 . The movable stopper  27  is a separate component which can be detached from the bracket  26  and has a function as a stopper for positioning the bracket  26 .  
         [0032]    An air cylinder  28  is mounted on the frame  10  while an end portion of its piston  28   a  is pressed against a slide frame  22 . This air cylinder  28  presses the bracket  26  against the movable stopper  27  when the motor  23  rotates to move the slide frame  22 . That is to say, the air cylinder  28  has a function of stabilizing stop of the slide frame  22  so as to improve its positioning accuracy.  
         [0033]    A shaft  29  whose axis line is directed vertically is supported rotatably on the slide frame  22 . An upper end portion of the shaft  29  is protruded from the slide frame  22  and a proximal end portion of the arm  30  is fixed to that upper end portion of the shaft  29 . Meanwhile, reference numeral  31  in the same Figure denotes a rib supporting the arm such that it is directed upward. An end portion of the arm  30  reaches over the bending head portion  60  while a damper (supporting device)  32  is provided on an upper face thereof. The damper  32  can be opened or closed and a groove (not shown) having a curvature radius slightly larger than that of a round bar which is a material W is formed in an inner peripheral face of the damper  32 .  
         [0034]    Next, the material feeding mechanism  40  will be described. A guide rail  41  is provided on an upper face of the arm  30  and a carriage  42  is supported slidably in a lateral direction with respect to FIG. 4 by the guide rail. A motor (rotating device)  43  is provided on the carriage  42  and the motor  43  rotates a chuck  45  which can be opened/closed via a reducer  44 . Although not shown, the arm  30  or the carriage  42  is provided with a motor and further an appropriate power transmitting device such as ball screw/ball nut mechanism, a timing chain and timing belt. By such a mechanism, the carriage  42  can be moved on the guide rail  41 . Reference numeral  42   a  in FIG. 5 denotes a cover of the carriage  42  and FIG. 4 indicates a condition in which the cover  42   a  is removed.  
         [0035]    Next, the bending head portion  60  will be described. A motor (driving device)  61  is mounted on the frame  10 . An output shaft  61   a  of the motor  61  is coupled to a reducer  62 . An output shaft  62   a  of the reducer  62  is protruded upward and an upper end portion thereof is inserted into the head  63 . A bending jig  64  is supported slidably and rotatably in a vertical direction at an end portion of the head  63 . An intermediate portion in the vertical direction of the bending jig  64  is connected to the output shaft  62   a  of the reducer  62  through an appropriate transmitting mechanism such as a timing chain. A bottom end portion protruded from the head  63  of the bending jig  64  is connected to an upper portion thereof such that it is relatively rotatable. An end portion of a lever  66  whose central portion is supported rotatably by a bracket  65  is mounted rotatably on the bottom end portion of the bending jig  64 . The other end portion of the lever  66  is attached rotatably to a piston  67   a  of a hydraulic cylinder  67 .  
         [0036]    A pair of bending blocks  68  are mounted on an upper end face of the bending jig  64 . The bending blocks  68  are separated from each other at an interval slightly larger than the diameter of material W. Although according to this embodiment, the bending blocks  68  are fixed, it is preferable to form them so that they can be opened/closed like the aforementioned damper  32 . In this case, a groove having a slightly larger curvature radius than the material W is formed in an inner peripheral face thereof. Reference numeral  69  denotes a stand, which fastens the head  63  to the frame  10 . Reference numeral  70  denotes a bracket, which fastens the hydraulic cylinder  67  to the stand  69 .  
         [0037]    Next, a pair of hydraulic or pneumatic piston cylinders  71  are mounted via a bracket  72  on a rear end portion of the head  63 . The piston cylinder  71  presses side faces of the arm  30  equally by device of its piston  71   a  so as to adjust the arm tilted after the material W is bent to a straight position.  
         [0038]    B. Operation of the first embodiment  
         [0039]    Next, the operation of the bending apparatus having the above-described structure will be described.  
         [0040]    A rear end portion of the material W is set to the chuck  45  of the material feeding mechanism  40  and a predetermined switch of a control panel (not shown) is turned on. Then, the chuck  45  grips the material W and the slide frame  22  moves so that an interval between the damper  32  and the bending block  68  becomes a distance set up to a first bending processing. Because at that time, the valve of the air cylinder  28  is closed, the slide frame  22  moves resisting a urging force of the piston  28   a.  Consequently, the stop of the slide frame  22  is stabilized so as to improve the positioning accuracy. Further, the carriage  42  moves so as to forward the material W up to the first bending position. The moving amount of the carriage  42  is corrected by adding a moving amount of the slide frame  22 .  
         [0041]    If the carriage  42  is forwarded, the material W is inserted into a gap in the damper  32  and a gap in the bending block  68 . If the material W is long, when the material W is set up in the chuck  45 , the material W may reach the damper  32  or the bending block  68 . Next, the damper  32  is closed to grip the material W and then, the bending jig  64  is rotated by an angle set as a first bending angle. Consequently, a substantially uniform moment is applied to the material W between the damper  32  and the bending block  68 , so that that corresponding portion is bent at the set curvature radius. At that time, the valve of the air cylinder  28  is opened so as to leave the slide frame  22  slidable. The arm  30  is rotated around the shaft  29  following a bending of the material W and simultaneously moves forward.  
         [0042]    Next, the piston  67   a  of the hydraulic cylinder  67  is stretched so that the bending jig  64  descends and then, the bending block  68  is released from the material W. Consequently, the arm  30  is made rotatable with respect to the shaft  29 . Then, the piston cylinders  71  are actuated so that the pistons  71   a  are stretched to press the side faces of the arm  30  equally. As a result, the arm  30  is positioned to a straight status relative to the bending jig  64 . Next, the slide frame  22  moves, so that an interval between the damper  32  and the bending jig  68  becomes the distance set for a second bending processing. In order to forward the slide frame  22  from its original position, the movable stopper  27  is forwarded and at that time, by throttling the valve of the air cylinder  28 , the bracket  26  is pressed against the movable stopper  27 . In order to retreat the slide frame  22 , the movable stopper  27  is retreated and the piston  28   a  of the air cylinder  28  is stretched so as to press back the bracket  26 . Next, the damper  32  is opened and the carriage  42  is forwarded to the second bending position so as to feed the material W and rotate the material W at a set angle.  
         [0043]    Next, the damper  32  is closed to grip the material W. At this time, the bending jig  64  is already rotated inversely and returned to its original angular position. Next, the bending jig  64  is raised so that the bending block  68  nips the material W. The bending jig  64  is rotated by an angle set as the second bending angle. After the material W is bent by a set frequency in this manner, the bending apparatus is stopped. Then, the chuck  45  and the damper  32  are opened by operating a predetermined switch on the control panel and the bent material W is taken out.  
         [0044]    The bending apparatus having the above described structure is capable of bending the material W at an arbitrary curvature radius and an arbitrary bending radius without using any special bending die. Because the material W can be bent even if the bending jig  64  is rotated in any direction, it is possible to prevent an interference between the material W and the bending apparatus or other attached equipment. Particularly in the above-described embodiment, the arm positioning mechanism  20  and the bending head portion  60  are separated and a reaction force to a moment generated in the shaft  29  (rotation fulcrum point of the arm  30 ) when the material W is bent is small. Further, because the length of the arm  30  is set sufficiently large, the reaction force generated in the shaft  29  is very small and a stress generated in the material W becomes substantially equal, thereby making it possible to obtain an equal curvature radius. Because the inner face of the damper  32  is formed in a configuration fitting to the outer periphery of the material W, it is possible to suppress flattening and generation of a pressure mark which may occur when the material W is bent, by forming the inner face of the bending block  68  in such a configuration.  
         [0045]    2. Second embodiment  
         [0046]    Next, the second embodiment of the present invention will be described with reference to FIGS. 6, 7. Reference numeral  80  in the same Figure denotes a frame and guide rails  81  are mounted on a top face of the frame  80 . A slide frame (moving device)  82  is supported slidably by the guide rails  81 . Although not shown, the slide frame  82  is moved by a similar motor, ball screw and ball nut to the first embodiment and supplied with a resistance during moving by an air cylinder. A rear end portion of the arm  83  is supported by the slide frame  82  rotatably. A front end portion of the arm  83  is fixed to the frame  80  such that a gate type frame  84  rides over an arm  83 . A supporting block (supporting device)  85  is mounted on a top face of the gate type frame  84 .  
         [0047]    A bending jig  86  is mounted on a top face of the front end portion of the arm  83  and a bending block  87  is provided on a top face of the bending jig  86 . Although not shown, the bending jig  86  is slidable vertically due to the same structure as the first embodiment. A hydraulic cylinder (driving device)  88  is mounted on each of both side faces of the arm  83 . Both end portions of a timing chain  89  are coupled to the pistons  88   a  of the hydraulic cylinder  88 . The timing chain  89  is wound such that it engages a sprocket (not shown) protruded from an outer periphery of the bending jig  86 . Reference numeral  90  in the same Figure denotes material feeding mechanism, which grips a rear end portion of the material W and feeds it in the axial direction and rotates it.  
         [0048]    Next, the operation of the bending apparatus of the second embodiment will be described.  
         [0049]    A rear end portion of the material W is gripped by the material feeding mechanism  90  and a predetermined switch of the control panel (not shown) is turned on. Consequently, the slide frame  82  is moved so that an interval between the supporting block  85  and the bending block  87  becomes a distance set for the first bending processing. At the same time, the material feeding mechanism  90  is forwarded up to a first bending position.  
         [0050]    If the material feeding mechanism  90  is forwarded, the material W is inserted into a gap in the supporting block  85  and a gap in the bending block  87 . Next, the hydraulic cylinder  88  is actuated and the bending jig  86  is rotated by an angle set as the first bending angle. As a result, a moment is applied to the material W in the gaps of the block  85  and the bending block  87  so that that corresponding portion is bent. At that time, the arm  83  is left slidable and rotatable, so that the arm  83  is moved following a bend of the material W.  
         [0051]    Next, the bending jig  86  descends so that the bending block  87  is released from the material W. With this condition, the slide frame  82  is moved and consequently, the interval between the supporting block  85  and the bending block  87  becomes the distance set for the second bending processing. The material feeding mechanism  90  forwards the material W up to a second bending position and rotates the material W by a set angle. Next, the bending jig  86  is rotated inversely and returned to its original angular position and raised so that the bending block  87  nips the material W. The bending jig  86  is rotated by an angle set as the second bending angle by operation of the hydraulic cylinder  88 . A set number of bending processings are carried out to the material W and then, the processing is completed.  
         [0052]    With the bending apparatus having the above-described structure, substantially the same operation and effect as the first embodiment can be obtained. Because a winding drive source of the bending jig  86  is mounted on the arm  83 , a reaction force of a moment given to the material W by the bending jig  86  is applied to the shaft  82   a.  As a result, an additional moment is applied to the material W so that the material W is not bent entirely at an equal curvature radius. Thus, it is recommendable to so construct that a rotation of the motor  91  is transmitted to the bending jig  86  through a reducer  92  or a universal joint  93  instead of the hydraulic cylinder  88  as shown in FIG. 7. Despite the structure shown in FIG. 6, changes of the curvature radius can be made negligible by increasing the distance between the shaft  82   a  and the supporting block  85  sufficiently.  
         [0053]    3. Variations of the Embodiments  
         [0054]    The present invention is not restricted to the above described embodiments but may be modified in the following various ways.  
         [0055]    (1) By setting a moving distance of the slide frame  82  sufficiently long in the second embodiment, it can be provided with a function of the material feeding mechanism  90  at the same time. That is to say, instead of the material feeding mechanism  90 , a stand for supporting material is disposed and the supporting block  85  and the bending block  87  are so constructed as dampers which can be opened/closed. By bringing a rear end portion of the material into contact with the stopper of the stand, the material is positioned and a front end portion of the material is gripped by the bending block  87 . Next, after the material is set on a first bending position by forwarding the slide frame  82 , the material is clamped with the supporting block  85  and at the same time, the bending block  87  is opened. By retreating the slide frame  82 , the bending block  87  is set on the first bending position and rotated so as to bend the material. Such a structure can be applied to the first embodiment also.  
         [0056]    (2) The first embodiment may be so constructed that the bending jig  64  can be rotated by using a hydraulic cylinder.