Patent Publication Number: US-6655183-B1

Title: Lifting mechanism for a head member of a pipe bender

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lifting mechanism for a head member of a pipe bender, and more particularly a lifting mechanism for a head member of a pipe bender, which can make the head member move up and down smoothly, and eliminate the risk of undesirable downward movement of the head member caused by oil leakage or other breakdowns of the hydraulic cylinder. 
     2. Brief Description of the Prior Art 
     Referring to FIGS. 7 and 8, a conventional pipe bender includes a head member  10 , a molding member  20 , a foldable hand member  30 , and a feeding element  40 . The head member  10  is tip and down movably disposed at a front end of the pipe bender. The molding member  20 , and the foldable hand member  30  are fitted to the head member  10 . Ad, the feeding member  40  is fitted on the main body of the pipe bender for feeding pipes to the head member  10 . 
     The head member  10  is equipped with a rear guide block  101 , a rear guide mould  102 , a guide block  103 , and a guide mould  104 . The molding member  20  consists of several decks of molding wheels  201  of different diameters. The foldable hand member  30  includes an upper clipping element  301 , and a lower clipping element  302  arranged beside corresponding molding wheels  201 . 
     In using such pipe bender, pipes fed to the head member  10  via the guide moulds  102 ,  104  on the head member  10  are clipped by means of one of the clipping elements  301 , and  302 . Then, the clipping element  301  or  302  operate to press the pipes over the corresponding molding wheel  201  so that the pipes are bent in conformity with shapes and diameters of the molding wheel  201 . 
     Referring to FIGS. 9 and 10, the head member  10  is fitted to vertical guide rails at one side, and equipped with a lifting mechanism  50  comprising a hydraulic cylinder  501 , which is disposed under the head member  10  with a piston rod  502  propping the bottom of the head member  10 . Thus, the lifting mechanism  50  can be operated to adjust the height of the head member  10 . After the head member  10  is adjusted to a desired height, pipes fed from the feeding member  40  can be clipped by one of the clipping elements  301 ,  302  that is as high as it, and then shaped in accordance with the corresponding molding wheel  201  when the clipping element is operated. 
     However, the lifting mechanism for head member is found to have disadvantages as followings: 
     1. The entire weight of the head member  10  is supported by the cylinder  501  therefore the lifting mechanism will have shortened service life. And, the head member will undesirably move down due to gravity if there is breakdown in the cylinder or leakage in the oil circuit. 
     2. The head member  10  is prone to vibrate because it is relatively heavy in weight. Consequently, the head member  10  will have reduced precision. 
     3. Because the hydraulic cylinder  501  of the lifting mechanism is disposed under the head member  10 , it is likely to interfere with bending process of pipe benders. 
     SUMMARY OF THE INVENTION 
     It is a main object of the present invention to provide a lifting mechanism for a head member of a pipe bender such that the head member can be moved up and down smoothly. 
     It is another object of the present invention to provide a lifting mechanism for a head member of a pipe bender such that an oil cylinder thereof do not have to bear the weight of the head member after the head member has been moved to desired position, eliminating the risk of undesirable downward movement of the head member caused by oil leakage or other breakdowns of the hydraulic cylinder. 
     The present lifting mechanism includes a connecting block, and an oil cylinder. The connecting block is joined to the head member. The oil cylinder is horizontally fitted to the main body of the pipe bender. The connecting block is equipped with a propped block on the bottom. The propped block has several horizontal propped surfaces on the bottom, which are formed at different heights with slopes formed in between. Wheels are fitted to the piston rod of the cylinder to prop up the propped block. Therefore, when the cylinder operates for the wheels to move relative to the propped block, the head member can be moved up and down. The piston rod stops moving when the wheels are positioned under one of the horizontal propped surfaces, therefore the cylinder don&#39;t have to bear the weight of the head member all the time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood by reference to the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view of the lifting mechanism for a head member of a pipe bender according to the present invention. 
     FIG. 2 is a top view of the lifting mechanism for a head member of a pipe bender according to the present invention. 
     FIG. 3 is another side view of the lifting mechanism of the present invention. 
     FIG. 4 is a view of the lifting mechanism of the present invention under operation. 
     FIG. 5 is a side view of the lifting mechanism according to the second embodiment of the present invention. 
     FIG. 6 is a side view of the lifting mechanism according to the third embodiment of the present invention. 
     FIG. 7 is a perspective view of the conventional pipe bender as described in the Background. 
     FIG. 8 is a perspective view of the head member of the conventional pipe bender in FIG.  7 . 
     FIG. 9 is a front view of the head member of the conventional pipe bender. 
     FIG. 10 is a side view of the head member of the conventional pipe bender. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1,  2  and  3 , a lifting mechanism according to the present invention is fitted to a main body  1  of a pipe bender, which is substantially the same as the one described in the Background. The present lifting mechanism includes an oil cylinder  2 , and a connecting block  3 . 
     The oil cylinder  2  is fitted to the main body  1  of the pipe bender in a horizontal position, and has a piston rod  21  directed to an opening of the main body  1 . A pushing support  22  is connected to an outer end of the piston rod  21  at a first end thereof The pushing support  22  is equipped with wheels  23  at other end. 
     The connecting block  3  includes a connecting portion  32 . The connecting block  3  is associated with vertical guide rails (not shown) on the front of the main body  1  so that it can be moved up and down. The connecting portion  32  sticks out through the opening  11  of the main body  1 , and is fixedly joined to a head member of the pipe bender so that the head member can be moved together with the connecting block  3 . A propped block  31  is joined to a lower side of the connecting block  3 . The propped block  31  is formed with spaced horizontal propped surfaces  312 , and  313  at different heights. The propped block  31  further has a slope  311  formed between the propped surfaces  312 , and  313 . Thus, the wheels  23  are faced with the slope  311 , and the propped surfaces  312 ,  313 . 
     To adjust the head member of the pipe bender in height the oil cylinder  2  is operated to move the piston rod  21  so that the wheels  23  move relative to the slope  311 . The movement of the piston rod  21  is stopped when the wheels  23  prop up the propped block  31  by means of positioning the same under a selected one of the horizontal propped surfaces  312 ,  313 . Thus, the head member is stably supported at desired height together with the connecting block  3 , allowing pipes fed from the main body  1  to be pressed over a corresponding one of molding wheels disposed on the head member in the pipe bending process. The cylinder  2  operates for the piston rod  21  to retreat so that the head member is lowered, allowing pipes fed from the main body  1  to be pressed over an upper one of the molding wheels. 
     Referring to FIG. 5, a propped block  31  of the second embodiment is formed with more than two horizontal propped surfaces  312 ,  313 , and  314  at different heights, and similarly slopes are formed between the propped surfaces. Thus, there are more options in adjusting height of the head member. 
     Referring to FIG. 6, in yet another embodiment of the present invention, wheels  32  are fitted to a bottom of the connecting block, and a propping block  24  is fixedly connected to the pushing support  22 , which is joined to the outer end of the piston rod  22 . The propping block  24  has several spaced horizontal propping surfaces (not numbered) on an upper side thereof. The paced horizontal propping surfaces are formed at different heights with slopes formed in between. 
     Therefore, when the oil cylinder  2  is operated to move the piston rod, the propping block  24  will move relative to the wheels  32 . The movement of the piston rod is stopped when the propping block  24  prop up the wheels  32  with a predetermined one of the horizontal propping surfaces being positioned under the wheels  32 . Thus, the head member is stably supported at desired height together with the connecting block  3 . 
     From the above description, it can be easily seen that the lifting mechanism for a head member of a pipe bender of the present invention has advantages as followings: 
     1. The entire weight of the head member is supported by the wheels instead of by the cylinder therefore there is no possibility of service life of the oil cylinder being shortened due to the persistent pressure from the head member. And, the head member will still be stably supported in position even if there is breakdown in the cylinder or leakage in the oil circuit. 
     2. With the wheels and the shaped block working together to move the bead member up and down, vibration of the head member with the present lifting mechanism is relatively little as compared with that occurring in the conventional head member. Consequently, precision of the head member will not be reduced by vibration. 
     3. The oil cylinder and the propping block of the lifting mechanism is disposed in the main body of the pipe bender instead of under the head member, therefore they will not interfere with bending process of pipe benders, allowing the pipe bender to operate smoothly.