Patent Publication Number: US-6698532-B2

Title: Piercing apparatus

Description:
This application is a divisional application under 35 U.S.C. §120 and §121 of prior application Ser. No. 09/567,640 filed May 9, 2000, now U.S. Pat. No. 6,601,655. The entire disclosure of prior application Ser. No. 09/567,640 filed May 9, 2000 is considered part of the divisional application and is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a piercing apparatus suited for use as an iron runner port-opening machine for a blast furnace, or the like furnace, in an iron and steel factory. 
     2. Description of the Related Art 
     As an iron runner port-opening machine for a blast furnace, or the like furnace, in general, there has been widely used a hydraulic drifter having a cylinder for slidably holding a piston that moves back and forth, and a sleeve for holding a shank rod attached to a front portion of the cylinder, so that the piston is advanced by the hydraulic pressure supplied to the cylinder to blow the shank rod. A piercing rod is joined to an end of the shank rod, and a bit is attached to an end of the piercing rod to execute the piercing. During the piercing operation, a thrust is imparted to the drifter by a feed unit provided on a support unit that supports the drifter when the piercing is effected to a desired depth, the drifter is moved back to withdraw the piercing rod and the bit from the hole that is pierced. In this case, however, there frequently occurs an accident, i.e., a so-called jamming in which the bit is not easily withdrawn as the pierced hole is stuffed with the pulverized scraps on the back side of the bit. 
     In order to easily withdraw the bit and the rod despite such an accident has occurred, there has been already developed a hydraulic piercing apparatus equipped with a reverse-blowing unit to give a backward blow to the rod (Japanese Patent No. 2613538). The piercing apparatus equipped with the reverse-blowing unit has been widely used for opening the iron runner port of a blast furnace, since it makes it possible to relatively easily withdraw the rod by actuating the reverse-blowing unit when the rod cannot be withdrawn. On the site of work of this kind, however, much limitation is imposed on the working space, and it has been urged to provide a more compact piercing apparatus. Besides, the above conventional piercing apparatus requires at least five thick hydraulic hoses for operating the piercing apparatus, i.e., a hydraulic hose for forward blowing, a hydraulic hose for reverse blowing, a hydraulic hose for forward rotation, a hydraulic hose for reverse rotation, and a return hydraulic hose for forward and reverse blows, resulting in a complex external structure and hindering the operability. 
     SUMMARY OF THE INVENTION 
     It is therefore a requirement of the present invention to provide a piercing apparatus which is compact in size and uses a decreased number of hoses as a result of improving the above-mentioned conventional forward/reverse blow-type piercing apparatus. 
     In order to solve the above assignment, the present invention employs the following constitution. That is, the piercing apparatus of the invention executes the piercing by moving, back and forth by using a feed unit, a drifter equipped with a forward-blowing unit, a reverse-blowing unit and a rotary unit; wherein 
     cylinders containing a cylindrical blowing piston are provided in front of, and at the back of, a drifter body maintaining a distance relative to each other; 
     a shank rod having, formed as a unitary structure, a blowing portion of a large diameter with blowing surfaces formed on the front and rear portions thereof and rod-like small-diameter portions protruding forward and backward beyond the blowing portion, is provided along the axial direction of the drifter body in a manner that the blowing portion is positioned between the front cylinder and rear cylinder and that the small-diameter portions on both sides are fitted to the cylindrical blowing pistons of the respective sides; and 
     valves are provided in the outer peripheral portions of the front and rear cylinders to supply hydraulic pressure into the cylinders. 
     The rotary unit can be constituted in a relatively compact size if a spline is formed in the outer peripheral portion of the blowing portion of the shank rod, and if a chuck that transmits the rotation, by being spline-fitted to the blowing portion, is rotated by the rotary unit provided on the outer peripheral portion of the drifter body. 
     Further, a pilot valve unit is provided on the outer peripheral portion of the drifter body to selectively change the hydraulic pressure for blowing over to the valve for forward blowing or over to the valve for reverse blowing, and is changed over by the hydraulic pressure supplied to the feed unit in a manner that the hydraulic pressure is supplied to the valve for forward blowing by the hydraulic pressure for moving the feed unit forward and that the hydraulic pressure is supplied to the valve for reverse blowing by the hydraulic pressure for moving the feed unit backward. Then, the forward blow and the reverse blow are automatically changed over depending upon the change-over of the feed. 
     It is desired that a pilot valve unit for selectively changing the hydraulic pressure for rotation, over to the valve for forward rotation or over to the valve for reverse rotation, is provided on the outer peripheral portion of the drifter body from the standpoint of shortening the conduits and decreasing the size. 
     In the above piercing apparatus, it is desired to install, in a heat-resistant box, a valve for changing over all or part of the hydraulic pressure supplied to the blowing unit, rotary unit and feed unit and a valve for controlling the flow rate and pressure, and to install a cooling unit for forcibly cooling the interior of the heat-resistant box by purging the air as means for cooling the heat-resistant box. With the valve unit being installed near a guide cell for moving the drifter, the valve system can be constituted in a compact size. Similarly, it is desired to install, in a similar heat-resistant box, a valve for changing over all or part of the hydraulic pressure supplied to the blowing unit, rotary unit, feeding unit and to the pilot valve that changes over the direction of the blowing unit and the rotary unit, as well as to install a control valve for controlling the flow rate and pressure. 
     It is further desired from the standpoint of compactly arranging the hydraulic conduits that a return hydraulic pressure from the forward-blowing unit and the reverse-blowing unit meet a return hydraulic pressure from the rotary unit and/or the feed unit through the valve unit, so that the return hydraulic pressure is returned to a fluid tank through a common hydraulic hose. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical sectional view of a drifter according to an embodiment of the invention and illustrates a portion thereof in an expansion plan; 
     FIG. 2 is a plan view of FIG. 1; 
     FIG. 3 is a side view of FIG. 1; 
     FIG. 4 is a back view of FIG.  1 : 
     FIG. 5 is a sectional view along X—X of FIG. 2; 
     FIG. 6 is a diagram schematically illustrating hydraulic conduits; 
     FIG. 7 is a diagram schematically illustrating hydraulic conduits different from those of FIG. 6; 
     FIG. 8 is a diagram schematically illustrating hydraulic conduits further different from those of FIG. 6; 
     FIG. 9 is a view schematically illustrating the principle of operation of a piston; 
     FIG. 10 is a view schematically illustrating the principle of operation of the piston; 
     FIG. 11 is a view schematically illustrating the principle of operation of the piston; 
     FIG. 12 is a view schematically illustrating the principle of operation of the piston; 
     FIG. 13 is a view schematically illustrating the principle of operation of the piston; 
     FIG. 14 is a plan view illustrating an example of using a piercing apparatus of the invention as an iron runner port-opening machine; and 
     FIG. 15 is a side view of FIG.  14 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, an embodiment of the invention will be concretely described. The drawings illustrate an embodiment of the invention wherein, as shown in FIG. 1, a main body  2  of a drifter  1  of the piercing apparatus is provided with a cylinder  3  for forward blowing and a cylinder  4  for reverse blowing arranged in series at a predetermined distance. Bushings  6  and  7  are provided at both front and rear ends of the cylinder  3  for forward blowing, and a hollow rear cap  5  in the shape of a bag is secured by bolts to the rear portion of the cylinder  3 . A bushing  9  is provided in the inner surface of the rear cap  5 . 
     An intermediate cylinder  10  is connected between the cylinder  3  for forward blowing and the reverse-blowing unit. A chuck driver  13  having a tooth train  13   a  formed on the outer peripheral surface thereof is rotatably supported by bush in the inner periphery of the intermediate cylinder  10 , and a chuck  15  is fitted into the chuck driver. The chuck  15  is divided into two chuck pieces  15   a ,  15   a  of nearly a fan shape, and a female spline  15   c  is formed in the inner surface of each of the chuck pieces  15   a ,  15   a . On the inner surface of the chuck driver  13  are formed protuberances  13   a ,  13   a  protruding in the direction of diameter, and the chuck pieces  15   a ,  15   a , of nearly a fan shape fitted in the chuck driver, are brought into contact therewith so as to be coupled and secured. 
     Bushings  16 ,  17  are provided at both front and rear ends of the cylinder  4  for reverse blowing connected to the front side of the intermediate cylinder  10 , and a front head  19  having bushings  18 ,  19  provided in the inner surface side thereof is attached to the front side of the cylinder. 
     A rod-like shank rod  20  is inserted in the main body  2  of the drifter  1 . The shank rod  20  is provided with a junction portion  22  of a large diameter having an internally threaded portion  22   a , and is further provided with a blowing portion  23  of a large diameter at the intermediate portion thereof and with a slide portion  24  at the rear end thereof. A gap portion  20   a  between the junction portion  22  and the blowing portion  23 , and a gap portion  20   b  between the side portion  24  and the blowing portion, are in the form of a round rod of a small diameter. 
     The blowing portion  23  of the shank rod  20  is formed nearly in the shape of a drum, both the front surface  23   b  and the rear surface  23   a  thereof serving as blowing surfaces. A male spline  25  is formed on the outer periphery of the blowing portion  23  and is fitted to the female spline  15   c  of the chuck. 
     A cylindrical piston  30  for forward blowing is fitted onto the round rod portion  20   b  on the rear side of the shank rod  20 , and a cylindrical piston  33  for reverse-blowing is fitted onto the round rod portion  20   a  of the front side. A small gap t is maintained between these pistons and the round rod portion, so that the pistons are allowed to freely move back and forth. 
     The piston  30  for forward blowing and the piston  33  for reverse blowing have an equal size but are directed opposite to each other. Further, the cylinders  3  and  4  containing these front and rear pistons have the same shape and the same size, but are directed opposite to each other. Valve units  40 ,  43  for actuating the pistons are mounted on the outer peripheries of the cylinder  3  for forward blowing and of the cylinder  4  for reverse blowing. 
     A pilot valve unit  45  for blowing is mounted on the upper surface on the outer periphery of the intermediate cylinder  10  of the drifter  1 , and a rotary pilot valve unit  47  for changing the rotation over to the forward direction or the reverse direction is mounted on the side surface thereof. In FIG. 1 illustrating the operation system, the rotary pilot valve unit  47  is shown in an expansion plan for the purpose of convenience and, hence, the two pilot valve devices  45  and  47  are shown being overlapped one upon the other. A rotary unit  50  is provided on the side surface of the intermediate cylinder  10  on the side opposite to the pilot valve unit  47 . The rotary unit  50  includes a hydraulic motor  51  and a counter gear  52 , the counter gear being in mesh with the tooth train  13   a  of the chuck driver  13 , so that the rotation of the hydraulic motor  51  is transmitted to the chuck driver  13  through the counter gear  52 . 
     Next, actions of the pilot valve units  45 ,  47  will be described based on the diagram of operation system. In the case of forward blowing, first, a high-pressure fluid enters into the pilot valve unit  45  for blowing through a port Pa when the drifter  1  moves forward and enters into the valve unit  40  for forward blowing passing through a port Pf to actuate the piston  32  for forward blowing. The return fluid at this moment is returned back to the fluid tank through port Pg, port Ph and port Pc. 
     In the case of the reverse blowing, the high-pressure fluid enters into the pilot valve unit  45  for blowing through the port Pa when the drifter  1  moves back. In this case, the pressurized fluid acts upon the pilot port Pd from a feed-backward circuit for moving the drifter  1  backward. When the pressurized fluid overcomes the pushing force of the spring  59 , the valve  60  is changed over, and the pressurized fluid from the port Pa enters into the valve unit  43  for reverse blowing passing through the port Pi to actuate the piston  33  for reverse blowing. At this moment, the return fluid is sent back to the fluid tank through port Pj, port Ph and port Pc. 
     In the case of the forward rotation, the high-pressure fluid enters into the pilot valve unit  47  for rotation through the port Pb during the piercing, and reaches a forward rotation port P 1  of the hydraulic motor  51  through the port Pk to rotate the shank rod  20  forward. In this case, the return fluid enters into the port Pn from the reverse rotation port Pm of the hydraulic motor  51 , meets the return fluid from the blow return port Ph, and is returned back to the fluid tank through port Pc. 
     The reverse rotation is used for removing the rod fitted into the threaded portion of the junction portion of the shank rod  20 . In this case, the high-pressure fluid enters into the pilot valve unit  47  for rotation at the feed-backward end through the port Pb and, at the same time, the fluid pressurized high enough to overcome the pushing force of the spring  61  acts on the pilot port Pe through the pilot port Pd, whereby the valve  65  is changed over, so that the pressurized fluid arrives at a reverse rotation port Pm of the hydraulic motor  51  through port Pb and port Pn thereby to rotate the shank rod  20  in reverse. The return fluid at this moment enters into the port Pk from the forward rotation port P 1  of the hydraulic motor  51 , enters the blow return port Ph, and is returned back to the fluid tank through port Pc. 
     FIGS. 6 to  8  are diagrams of hydraulic conduits for operating the piercing apparatus  1 , wherein local constitutions are slightly different depending upon the drawings. The drawings of these conduits do not include the conduits for swinging, moving up and down or centering up and down, the guide cell on which the drifter is mounted. As shown, the piercing apparatus  1  is provided with three thick hydraulic hoses, i.e., a hydraulic pressure feed hose (blow IN) Hi for blowing and rotating the drifter, a hydraulic pressure feed hose for rotation (rotation IN) Hr, and a return line (T-line) Ht returning from the blowing unit and the rotary unit. Further, to the feed unit for moving the drifter forward and backward, are connected two hydraulic hoses, i.e., a hydraulic hose Ha for feed forward and a hydraulic hose Hb for feed backward. 
     In the example of conduits of FIG. 6, a narrow pilot hose Hp for changing over the forward/reverse blow is connected to the conduit for feed backward, whereby a pilot pressure acts from the line of feed backward on the pilot valve Vp for changing over the forward/reverse blow so that, at the time of moving back, the blow is automatically changed over to the reverse blow. The rotation is usually in the forward direction. When the reverse rotation is required, a forward/reverse change-over solenoid valve Vs of the valve unit provided in the valve stand is turned on, thereby to obtain the rotation in the reverse direction. 
     FIG. 7 illustrates an example of conduits different from the above example. In this example of conduits, a narrow pilot hose Hp from the conduit for feed backward is connected to the valve Vs for changing over the rotation and to the pilot valve Vp for changing over the forward/reverse blow so that, when the load is exerted during the feed backward, the blow is automatically changed from the forward blow over to the reverse blow and the rotation is changed from the forward rotation over to the reverse rotation. In general, the reverse blow is required at the time of withdrawing the rod (metal rod) or when the load is exerted during the feed backward, In order to prevent the screws from being loosened at the coupling portions, the drifter is rotated forward. And a some degree of pressure is applied to the circuit for forward rotation and, besides, the valve spring sp produces a force. Therefore, the forward rotation is not changed over to the reverse rotation by the pilot pressure in the feed-backward circuit. The drifter must be rotated in reverse at the time when the operation is finished and the rod (metal rod) must be removed. In this case, the feed is brought to the backward limit, and the drifter is rotated in a state where the solenoid valve for backward motion is turned on (in a state where the pressure is exerted on the backward circuit); i.e., the drifter is rotated in the reverse direction. The method of FIG. 7 minimizes the number of conduits between the valve stand and the drifter. 
     FIG. 8 illustrates a further different example of the conduits. In this example of the conduits, the pilot valve for changing over the forward-reverse blow/forward-reverse rotation is actuated by an electromagnetic valve in the valve stand. According to this method, the individual modes are selected relying on the combinations of operations of the electromagnetic valves. Then, the forward/reverse blow and the forward/reverse rotation can be arbitrarily selected and executed. 
     Next, the blowing operation of the drifter  1  will be described with reference to the drawings. FIGS. 9 to  13  illustrate the reverse-blowing unit. In FIG. 9, the piston  33  is reaching the top dead center (front end position) and the high-pressure fluid acts on a rear piston chamber S 1  from a high-pressure port D 1 . There is a relationship M 1 &gt;M 2  between the pressure-receiving area M 1  of the rear piston chamber S 1  and the pressure-receiving area M 2  of a front piston chamber S 2 . As the high-pressure line is communicated with the rear piston chamber S 1 , therefore, a force acting on the rear part of the piston becomes larger than a force acting on the front part of the piston, and the piston enters into the blowing stroke and moves forward (moves toward the right in the drawing). 
     In FIG. 10, the piston  33  continues to move forward and during this period, the accumulator A supplies the lacking amount of operation fluid. The piston further proceeds, and the large diameter portion  33   a  thereof opens the valve change-over port D 3  so that it is communicated with a port D 2  of the low-pressure line LP. Then, the pressure in the valve change-over chamber S 4  decreases and the valve V starts changing over. 
     In FIG. 11, the piston  33  reaches a point of reverse blow, transmits the kinetic energy which it has gained during the stroke of reverse blow to the shank rod  20  which then transmits the energy of reverse blow to the bit. At this moment, the valve V has been completely changed over, whereby the ports (D 1 , D 2 , D 3 ) are all communicated with the low-pressure line LP, the force acting on the front part of the piston  33  becomes larger than the force acting on the rear part of the piston, and the piston enters into the stroke of moving backward. As the piston further moves forward beyond the point of reverse blow with no load, the piston closes the port D 5 , comes into a halt while forming a cushion chamber S 3  and, then, starts moving backward. 
     In FIG. 12, the piston  33  continues to move backward, and the large diameter portion  33   a  opens the valve change-over port D 4  so that it is communicated with the port D 5  of the high-pressure line HP. Then, the pressure is elevated in the valve change-over chamber S 4 , and the valve V starts changing over. 
     In FIG. 13, the piston  33  for reverse blow continues to move backward and the valve V continues to be changed over. Then, the port D 1  is communicated with the high-pressure line HP, and the high-pressure fluid enters into the rear piston chamber. Due to the inertial energy which the piston has gained during the stroke of backward movement, the rear piston chamber forms a cushion chamber in the high-pressure line, and the hydraulic pressure is accumulated in the accumulator A. As the valve V is completely changed over and the piston reaches the top dead center at where it is stopped by the cushion, the initial state of FIG. 7 is resumed. 
     The foregoing description has dealt with the operation of the reverse-blowing unit. The same, however, also holds for the case of the forward-blowing unit (the direction is reversed) which, therefore, is not described here. 
     FIGS. 14 and 15 illustrate an example of using the piercing apparatus M as an iron runner port-opening machine for a blast furnace F, wherein the drifter  1  of the piercing apparatus M is attached to the guide cell  71  in a manner to move back and forth. The base portion of the guide cell  71  is supported by an arm  73  hanged from a swing base  72  via a shaft  74  so as to freely rotate up and down, and an intermediate portion thereof is supported by a lift unit  75 . Reference numeral  77  denotes a hydraulic cylinder for lifting. Upon expanding and contracting the hydraulic cylinder  77 , the guide cell turns up and down with the shaft  74  as a center. In the drawing, reference numeral  79  denotes a five-way swivel for the air and water, and  80  denotes an up-down centering unit for centering the guide cell in the up-and-down direction. The position of the end of the guide cell is adjusted in the up-and-down direction by forwardly or reversely rotating an air motor  81  for accomplishing the centering in the up-and-down direction. 
     In the drawing, reference numeral  85  denotes a hydraulic feed motor constituting a feed unit F attached to the guide cell  71 . When the hydraulic feed motor  85  is rotated forward or reverse, a sprocket attached to the rotary shaft of the motor rotates, and a chain wrapped round the sprockets attached to the front end and the rear end of the guide cell moves back and forth. A carriage  87  is attached to the chain, and the drifter  1  is mounted on the carriage. Therefore, the drifter  1  moves back and forth accompanying the motion of the chain. Reference numeral  90  denotes a pump unit,  91  denotes a valve unit (containing a small manifold electromagnetic block) for the drifter,  92  denotes a valve unit containing an electromagnetic valve block for the lifting unit for raising and lowering the guide cell  71 , reference numeral  93  denotes a valve stand mounting a valve unit for swinging,  95  denotes a safety hook rotated by an air cylinder  95   a , reference numeral  96  denotes an air electromagnetic valve box, and  97  denotes an encoder for detecting the depth of the hole. 
     The valve unit  91  for the drifter is the one in which the valve for changing over whole or part of the hydraulic pressure supplied to the blowing unit, rotary unit and feed unit, and the valve for controlling the flow rate and pressure, are installed in a heat-resistant box mounted on the guide cell, and is provided with cooling means for forcibly cooling the interior of the heat-resistant box by purging the air or a like method. The valves that are contained in the box having resistance against the heat are protected from high temperatures when the apparatus is used for opening the iron running port of the blast furnace and, besides, the apparatus is realized in a compact size. It is further desired to contain, in the above heat-resistant box, the valve for changing over whole or part of the hydraulic pressure supplied to the pilot valve that changes over the directions of the blowing unit and of the rotary unit, as well as the valve for controlling the flow rate and pressure. 
     To use the piercing apparatus M as the iron running port-opening machine, a piercing rod R is connected to the shank rod  20  of the drifter  1 , and a bit is attached to the end of the piercing rod. The direction and inclination of the drifter  1  are so adjusted that the bit comes in contact with a desired piercing portion, the feed unit is actuated to fit the bit to the piercing position (e.g., iron running port Fa of the blast furnace), and the forward-blowing unit and the rotary unit are actuated. Thus, the piercing operation is executed as desired. 
     After the piercing is effected to a predetermined depth, the drifter  1  is moved backward to withdraw the bit and the rod from the hole that is pierced. At this moment, the feed unit is changed over to the side of moving backward, whereby the pilot valve unit  45  operates, and the supply of hydraulic pressure for blowing is changed from the valve for forward blowing over to the valve for reverse blowing. Thus, the blowing is changed from the forward blow which gives blow to the rod in the forward direction over to the reverse blow which gives blow in the reverse direction. Even in case the bit cannot be withdrawn due to the pieces and scraps of the piercing operation in the hole on the back side of the bit, the blow in the reverse direction helps to easily withdraw the bit. 
     The hydraulic pressure can be supplied from the hydraulic pump to the drifter  1  by using the hydraulic hose for forward blowing and the hydraulic hose for reverse blowing, and the return fluid from the blowing unit and the return fluid from the rotary unit are returned back to the fluid tank through the common hydraulic hose, making it possible to decrease the number of thick hydraulic hoses extending along the outer side, and the apparatus is realized in a compact size featuring easy operation. In the diagramed drifter, further, the rod connection portion of the shank rod is internally threaded enabling the external thread of the piercing rod to be directly screwed therein and connected. Compared to the prior art using a coupling sleeve, therefore, the blowing force can be efficiently transmitted. However, this portion may be constructed similarly to that of the prior art. 
     According to the piercing apparatus of the present invention as described above, the shank rod having, in the intermediate portion thereof, a blowing portion with blowing surfaces on the front and rear sides thereof, is used as a shank rod of the drifter, cylindrical pistons are fitted to the front and rear sides of the blowing portion to apply forward/reverse blow by the pistons on the front and rear sides thereof. Therefore, the overall length is decreased to realize the apparatus in a compact size. Further, the pilot valve is provided for changing over the forward blow and the reverse blow. At the time when the device for feeding the drifter is changed over to the side of backward motion, the pilot valve is operated to change the forward blow over to the reverse blow. Accordingly, the hydraulic pressure feed (IN) hose can be used in common for the forward blow and for the reverse blow. Further, the return circuits of the blow and rotation are formed as a T-line, and the return fluids of the blow and rotation are returned back to the tank through the common return hose. Therefore, only three thick hoses are required, contributing to simplifying the external structure and improving the operability.