Abstract:
A crushing machine including a crushing means, a feed conveyor for feeding material to the crushing means, a detector for detecting metal in the material on the feed conveyor, and a bypass chute for the crushing means, the feed conveyor being movable between a normal operating position in which the material is fed to the crushing means and a bypass position in which the material is fed to the bypass chute, the arrangement being such that on detection of metal in the material, the feed conveyor is stopped and moved from the normal operating position to the bypass position so that the material with the metal is discharged into the bypass chute.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application and claims priority to U.S. patent application Ser. No. 13/740,708 filed on Jan. 14, 2013 and issued on Dec. 9, 2014 as U.S. Pat. No. 8,905,338 titled “Crushing Machines” and which is a divisional application and claims priority to allowed U.S. patent application Ser. No. 12/596,943 filed on Mar. 31, 2010 titled “Crushing Machines”, which is a U.S. National Stage filing under 35 U.S.C. §371 of International Application No PCT/GB2008/01396 filed on Apr. 21, 2008, which claims priority to United Kingdom Patent Application No. 0707761.3 filed on Apr. 21, 2007, the disclosures of each of which are incorporated herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to crushing machines for crushing aggregate and the like; and in particular to mobile crushing machines such as are used in quarries or for recycling demolition waste. 
         [0003]    One type of crushing machine uses a crusher. A cone crusher has a pair of frustaconical members arranged with their apexes upwards, and with an annular gap between them that decreases in width from top to bottom. The inner cone is rotatable relative to the outer cone on an eccentric, so that material fed in at the top is crushed between the cones as the gap varies, and then falls out at the bottom. Cone crushers are efficient at crushing various types of material, such as rock or stone, to a given size. However, it is important to ensure that no metal is fed into the crusher, since this can cause extensive damage to the cones. It is known to address this problem by providing a metal detector on a conveyor feeding the material to the crusher, so that the machine operator can then stop the conveyor, find the metal in the material by hand, remove it and then restart the conveyor. This is time-consuming, and not a pleasant task for the operator. 
       SUMMARY OF THE INVENTION 
       [0004]    According to a first aspect of the invention, we provide a crushing machine including a crushing means, a feed conveyor for feeding material to the crushing means, a detector for detecting metal in the material on the feed conveyor, and a bypass chute for the crushing means, the feed conveyor being movable between a normal operating position in which the material is fed to the crushing means and a bypass position in which the material is fed to the bypass chute, the arrangement being such that on detection of metal in the material the feed conveyor is stopped and moved from the normal operating position to the bypass position so that the material with the metal is discharged into the bypass chute. 
         [0005]    The invention therefore provides a much easier and quicker way of removing metal from the material before it reaches the crushing means, since on detection of metal the conveyor can simply be stopped, and moved into the bypass position to discharge the metal into the bypass chute without the operator needing to look for the metal and remove it manually. It is particularly advantageous where the crushing means is a cone crusher, but may also be useful for other types of crusher. 
         [0006]    Once the material containing the metal has been discharged into the bypass chute, the feed conveyor is stopped again, moved back into the normal operating position and started, to resume discharge into the crushing means. 
         [0007]    The metal detector is preferably mounted on the feed conveyor, and sends a signal to the operator when metal is detected. 
         [0008]    The feed conveyor may be movable between the two positions by means of at least one hydraulic piston and cylinder assembly. The or each piston and cylinder assembly is conveniently double-acting. The piston may be connected to the feed conveyor, and the cylinder to a stationary part of the machine, although the opposite way round would also be possible. The piston and cylinder assembly or assemblies moves the feed conveyor longitudinally. The bypass chute is preferably arranged between the feed conveyor and the crushing means, SO that the feed conveyor moves rearwardly (opposite to the direction of travel of the material) from its normal operating position into its bypass position. The piston of the piston and cylinder assembly will be extended when the conveyor is in its normal operating position, and retracted when it is in its bypass position. The piston and cylinder assembly may have load-holding valves to lock the piston in position. 
         [0009]    The crushed material which exits the crushing means may fall onto a main conveyor for transport elsewhere. The material discharged into the bypass chute will be diverted away from the crushed material. It may simply fall to the ground, or into a convenient container. 
         [0010]    The invention is particularly useful where the crushing machine is a mobile crusher, having a tracked or wheeled base on which are mounted the feed conveyor, the bypass chute, the crushing means, the main conveyor, a power unit (typically a diesel engine) and a control system (including both manual and electronic controls). 
         [0011]    The control system is used for operating the conveyors and the crushing means, and may be sophisticated. Thus the control system may be adapted so that it automatically stops the feed conveyor when the signal is received from  t he metal detector. Further automation of the movement of the feed conveyor between the normal operating position and bypass position. may be possible, but normally the operator will control these movements: 
         [0012]    Another feature of a cone crusher is that it is more efficient and produces more evenly-sized crushed material, if the proportion of material that will pass through it without being crushed (commonly known as fines) is limited. One method of limiting the proportion of fines is to screen them out of the material before it is fed to the crusher. Currently, this requires a separate machine, which is expensive to buy (or hire) and to run. It also increases the time taken to process the material. 
         [0013]    According to a second aspect of the invention, we provide a crushing machine comprising a feed conveyor, a screening unit, a crushing means and a main conveyor, the arrangement being such that material to be crushed is fed from the feed conveyor to the screening unit, for separation into finer material which reaches the main conveyor without passing through the crushing means and coarser material which is fed in the crushing means to the main conveyor. 
         [0014]    Thus, a single machine incorporates a screening function as well as a crushing function, enabling the finer material to be screened out and not to pass through the crushing means. This is particularly advantageous where the crushing means is a cone crusher. Providing both functions in one machine thus reduces costs, both capital costs and running costs, including transport costs. 
         [0015]    The screening unit preferably comprises a screen conveyor and a vibrating mesh screen. Material from the feed conveyor is passed to the screen conveyor, from where it exits onto the mesh screen. Finer material falls through the screen, and onto the main conveyor, while the coarser material slides off the screen and into the crushing means. It will be appreciated that the screen must be angled to the horizontal. for the coarser material to slide off it. The screening unit is therefore conveniently arranged on the opposite side of the crushing means from the feed conveyor. 
         [0016]    The screening unit conveniently has a frame on which are mounted the screen and the screen conveyor. The frame is movable between an inoperative position, in which it is substantially horizontal, and an operative position, in which it is angled to the horizontal. The inoperative position is advantageous for transporting the machine. The screening unit may be moved between the two positions by at least one pair of hydraulic piston and cylinder assemblies, acting between a base off the machine and the screening unit. Preferably two pairs of assemblies are provided, one at each end of the screening unit. One pair acts vertically to lift the unit, while the other lifts and controls the angle of the unit. 
         [0017]    The screen conveyor is conveniently mounted on the frame by a further pair of piston and cylinder assemblies. These enable the angle of the screen conveyor to be adjusted relative to the screen, and also enable the screen conveyor to be lifted relative to the screen, to facilitate changing of the screen. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The two aspects of the invention are illustrated, by way of example only, in the accompanying drawings, in which: 
           [0019]      FIG. 1  is a side view of a mobile crushing machine in accordance with the first aspect of the invention and in a normal operating position; 
           [0020]      FIG. 2  is a detail of the machine of  FIG. 1  showing the bypass position; 
           [0021]      FIG. 3  is a side view of a. mobile crushing machine which illustrates both aspects of the invention, and shows the machine in a transport position; 
           [0022]      FIG. 4  is similar to  FIG. 3 , but shows the machine in an operating position; and 
           [0023]      FIG. 5  shows a detail of the machine of  FIGS. 3 and 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The machine of  FIG. 1  is a mobile crushing machine for crushing stone, aggregate and the like. The machine comprises a base  1 , on which are mounted a feed conveyor  2 , crushing means  3 , a power unit  4  including a control unit, and a main conveyor  5 . 
         [0025]    The base  1  has tracks  6  and an elongate platform  7  on which the other parts are mounted. with the feed conveyor  2  at the rear end, and the main conveyor  5  at the front end 
         [0026]    The feed conveyor  2  is of a known design having a frame S for a powered belt  9  and a feed chute  10  at the rear end of the belt  9  to receive material to be crushed. 
         [0027]    The frame  8  is mounted on the platform  7  by two pairs of hydraulic piston and cylinder assemblies  11 ,  12 . The assemblies  11  act vertically to raise and lower the forward end of the frame  8  with the cylinder  13  being attached to the platform  7 , and the pistons  14  pivotally mounted to the frame  8 . The assemblies  12  act to move the frame  8  in the longitudinal direction between the normal operating position of  FIG. 1 , and a bypass position of  FIG. 2 . The cylinders  15  are pivotally attached to an upstand  16  on the platform  7 , while the pistons  17  are connected to an abutment  18  on the underside of the frame  8 . The piston and cylinder assemblies  11 ,  12  are double-acting, and have load-holding valves (not shown) to lock the pistons in any desired position. The feed conveyor  2  also carries a metal detector  19 , mounted near the forward end of the belt, and adapted to send a signal&gt;to the control unit when metal is detected in the material on the feed conveyor  2 . 
         [0028]    The crushing means  3  comprises a cone crusher of known design, which need not be described further here. Material fed into the top of the crusher  3  from the forward end of the feed conveyor  2  is crushed, and fails out of the bottom of the crusher  3  onto the main conveyor  5 . 
         [0029]    The main conveyor  5 , mounted on the front end of the platform  7 , is also of a known design, and will not be described further here. 
         [0030]    The power and control unit  4  is also mounted near the front end of the platform  7 , and includes a diesel engine (not shown) as the power source for the machine, an hydraulic system (not shown) for operating the piston and cylinder assemblies  11 ,  12  and all other hydraulic components, and controls (not shown) for the machine. These are housed in a control area  20  for the machine operator. The controls include manual controls and electronic controls for automatically performing some operations. 
         [0031]    A bypass chute  21  is mounted on the platform  7  between the feed conveyor  2  and the crusher  3 . Material fed into the top of the chute  21  will not fall onto the main conveyor  5 , but instead will be discharged to the side of the machine, to fall onto the ground, or into a suitable container. 
         [0032]      FIG. 1  shows the machine in its normal operating position. 
         [0033]    The feed conveyor  2  is raised by means of the assemblies  11 , and the pistons  17  of the assemblies  12  are extended, so that the conveyor  2  is ready to discharge into the crusher  3 . Then, in operation, material placed in the feed chute  10  is carried upwards by the feed conveyor  2 , and discharged into the crusher  3 . The crushed material falls Out of the bottom of the crusher  3  onto the main conveyor  5 , and is discharged at the forward end of that conveyor into a suitable container. The operator controls the conveyors  2 ,  5  and the crusher  3  from the control area  20 . 
         [0034]    If the metal detector detects the presence of metal in the material on the feed conveyor  2 , it sends a signal to the electronic controls, which operate to stop the feed conveyor  2 . The operator then actuates the assemblies  12 , to retract the pistons  17 , causing the feed conveyor  2  to move rearwardly into the bypass position shown in  FIG. 2 , where the material on the feed conveyor is discharged into the bypass chute  21 , rather than the crusher  3 . The operator then starts the feed conveyor  2  again, so that the material including the metal is discharged into the bypass chute to fall on the ground at the side of the machine.. Once the operator is satisfied that the metal is no longer on the belt  9 , he stops the conveyor  2  and actuates the assemblies  12  to extend the pistons  17  again, thus moving the feed conveyor  2  back into the normal operating position. The feed conveyor  2  can then be restarted, and normal operation resumed. 
         [0035]    It will be appreciated that the machine is therefore able to deal with metal in the material quickly and easily, and without the operator needing to leave the control area  20 . 
         [0036]      FIG. 3  shows the machine of  FIG. 1  in a position in which it can be transported on a low loader or the like, and also illustrates the second aspect of the invention. In relation to the first aspect of the invention, however, it will be noted that for transport, the feed conveyor  2  is in the bypass position. 
         [0037]    The additional component of the machine shown in  FIGS. 3 and 4  is a screening unit  30 . The remainder of the machine is as shown in  FIG. 1 , and corresponding reference numerals have been applied to corresponding parts. Only the screening unit  30  will now be described. 
         [0038]    The screening unit  30  is mounted on the platform  7  between the crusher  3  and the control area  20 , It comprises a rectangular frame  31  that carries a vibrating mesh screen  32  and a screen conveyor  33 . The screen  32  is removably mounted in the frame  31 , since different sizes of mesh may be needed to screen different materials. The screen conveyor  33  is located above the screen  32 , and is mounted on the frame  31  by a pair of piston and cylinder assemblies  34 . This is best seen in  FIG. 5 , which shows the detail of the screening unit  30 . The cylinders of the assemblies  34  are attached to the frame  31 , while the pistons are pivotally attached to the screen conveyor  33 . Actuation of the assemblies  34  enables the angle of the screen conveyor  33  to be adjusted relative to the screen  32 , to facilitate changing of the screen  32 . 
         [0039]    The screening unit  30  also has a chute  35 , as shown in  FIG. 4 , for directing material passing through the screen  32  onto the main conveyor  5 . 
         [0040]    The frame  31  is mounted on the platform  7  by two further pairs of piston and cylinder assemblies  36 ,  37 . The pair  36  is at the rear end of the frame  31 , and acts vertically. The cylinders  38  of the assemblies  36  are attached to the platform  7 , while the piston  39  is pivotally attached to a projection  40  at the rear of the frame  31  The assemblies  37  act at an angle on the front end of the frame  31 . The cylinders  41  of the assemblies  37  are attached pivotally to a step  42  on the platform  7 , and the pistons  43  are pivotally attached to the front end of the frame  31 . 
         [0041]    In  FIG. 3  the screening unit  30  is in a horizontal position, for ease of transportation.  FIG. 4  shows the machine in its normal operating position, with the screening unit  30  raised by the assemblies  36 ,  37 , and the assemblies  34  extended to raise the screen conveyor  33  relative to the screen  32 . The screening unit  30  is then at an angle to the horizontal. The rear end of the screen conveyor  33  is below the discharge point of the feed conveyor  2 , while the discharge point at the front end is above the end of the screen  32 . The rear, lower end of the screen  32  is above the top of the crusher  3 . 
         [0042]    Thus, in operation, material discharged from the feed conveyor  2  falls onto the screen conveyor  33 , which in turn discharges it onto the vibrating screen  32 . The finer material passes through the screen  32  and falls through the chute  35  onto the main conveyor  5 , while the coarser material, which does not pass through the screen  32 , slides or rolls down the screen  32  and into the crusher  3 , crushed material, as in the embodiment for  FIG. 1 , then falls onto the main conveyor  5 . 
         [0043]      FIG. 5  shows how the screen  32  is changed. For this, with the screening unit  30  in its inoperative position, the operator actuates the assemblies  34  to extend the pistons, causing the screen conveyor  33  to be raised as shown. The operator can then easily reach the screen  32  to remove it and to insert a different screen. The assemblies  34  are then actuated to lower the screen conveyor  33  again, returning the unit  30  to its inoperative position. 
         [0044]    The advantage of the screening unit  30  is that it limits the proportion of finer material that passes through the crusher  3 , which then operates more efficiently. It will be appreciated that the advantages of including the screening unit  30  on the machine, rather than using a separate screening unit, are that capital and running costs (including transport costs) are reduced, as is set-up time. The time needed to change a screen is also minimized. 
         [0045]    Clearly, the two aspects of the invention may be used independently. If they are both incorporated in one machine it will increase efficiency accordingly,