Patent Publication Number: US-6669123-B2

Title: Crushing device

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a crushing device or comminutor for cuttings or chips from machining operations. 
     Crushing devices of such a kind are known and comprise a coarse breaking mechanism and a fine breaking mechanism. A hopper into which the cuttings can be filled, is arranged above the coarse breaking mechanism. First, the cuttings are torn by means of the coarse breaking mechanism, and then they are broken into short cuttings by the fine breaking mechanism. Afterwards, the short cuttings are discharged via a chute. 
     It sometimes happens that coarse pieces like, for example, iron pieces or tool parts are introduced into the hopper. Such coarse pieces are grasped by the coarse breaking mechanism and can cause a blockage of the entire apparatus. To remove such coarse pieces, it is necessary to open a window and to take the piece out of the system manually, which requires a considerable machine down-time. Furthermore, it happens occasionally that the fine breaking mechanism has already been damaged by the coarse piece, so that it has to be replaced. 
     SUMMARY OF THE INVENTION 
     The object underlying this invention is to improve a chip-crushing device of the kind described above in such a way that any coarse pieces which enter the crusher are detected before damage to the crushing device occurs. 
     Another object of the invention is to provide a crushing device in which coarse pieces which could damage the crusher are prevented from being caught in the fine breaking mechanism. 
     It is also an object of the invention to provide a crushing device which can automatically respond to entry of coarse pieces into the device and discharge such coarse pieces before they can jam or block the crusher. 
     These and other objects have been achieved in accordance with the present invention by providing a crushing device for cuttings, comprising a hopper for filling cuttings into the device, a tearing arm for coarse breaking of the cuttings, and a fine breaking mechanism, wherein the fine breaking mechanism comprises at least one centrally arranged grinding mechanism with a rotating blade head which operatively interacts with stationary teeth disposed peripherally around the grinding mechanism; the stationary teeth are disposed on at least two support segments; and the at least two support segments are movable in such a way that if a coarse piece enters the crushing device, the segments can be separated from the blade head, so that the coarse piece can be discharged from the crushing device. 
     A significant advantage of the present invention is that in the fine breaking mechanism, which comprises a grinding mechanism that operatively interacts with stationary teeth disposed on at least two support segments, the support segments are movable in such a way that they can be separated from the blade head of the grinding mechanism if any coarse pieces are introduced into the crusher, so that such coarse pieces are discharged from the crusher. It thus becomes unnecessary to provide any additional openings on the hopper for removal of coarse pieces. The coarse pieces can fall downwards into a container provided for them. Any damage to the blade head or grinding mechanism of the fine breaking mechanism is effectively prevented through opening of the stationary tooth supporting segments. 
     In accordance with one preferred embodiment of the invention, a flap is arranged below or at the side of the blade head onto which the coarse pieces are ejected. 
     In accordance with another preferred embodiment of the invention, two or more stationary tooth supporting segments are arranged to be movable outwardly in star shape. Thus, the grinding mechanism can be opened entirely, allowing coarse pieces to be ejected or discharged. The stationary tooth supporting segments can be arranged on slidable stages which can be driven either electrically or pneumatically. 
     It is likewise possible to drive the slidable stages hydraulically or to connect them to the driving motor by means of mechanical link rods. In the latter case, the rods open the grinding mechanism upon reversal of the driving motor. 
     According to a further exemplified embodiment, a sensor may be provided for sensing coarse pieces within the hopper and generating a control signal so that the stationary tooth bearing segments will open. 
     Alternatively, it is possible to recognize a coarse piece and then generate the respective control signals by monitoring changes in the torque of the grinding mechanism. It is even possible to detect the presence of a coarse piece by monitoring the load of the motor or the hydraulic drive and generating a corresponding control signal in response to a detected overload condition in order to activate the ejection of the coarse pieces. 
     These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or in the drawings, and the individual features each may be implemented in embodiments of the invention either singly or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawings in which: 
     FIG. 1 is a sectional view of a crushing device according to the invention; 
     FIG. 2 is a schematic representation of a two-part fine breaking mechanism, and 
     FIG. 3 is a schematic representation of a three-part fine breaking mechanism. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The crushing device according to FIG. 1 comprises a frame  10 , on which a filling hopper  11  is arranged. Inside the filling hopper  11  there is a coarse breaking mechanism  12 , comprised of a tearing arm  13  as well as teeth  14 ,  15  which are provided on the walls of hopper  11 . The tearing arm  13  is driven by motor  17 . 
     A fine breaking mechanism  20  is located below the hopper  11 . This fine breaking mechanism comprises a rotating blade head  16  as well as stationary teeth  18  and is likewise driven by motor  17 . The cuttings  22  to be crushed, for example metal strands, chips or shavings from machining operations, are introduced into hopper  11 . There they are grasped by tearing arm  13  and then reduced in size so that they can be fed to the fine breaking mechanism  20 . Beneath the tearing arm  13 , the cuttings enter the fine breaking mechanism, where they are processed into short cuttings. After passing through the fine breaking mechanism, the short cuttings are conveyed via a swiveling discharge chute  23  suitable for directing fine chips or coarse chips to a transport container (not shown). 
     If a coarse piece  24 , for example, an iron rod, a steel piece or a tool part, enters hopper  11 , it is likewise grasped by tearing arm  13  and teeth  14 ,  15  or by the fine breaking mechanism. A sensor  25  is provided to generate a control signal to actuate an ejector mechanism if a coarse piece enters the crushing device. The presence of a coarse piece is recognized by the sensor  25 , which then emits a detection signal. As a result of this signal, the movable segments which carry the stationary teeth of the fine breaking mechanism will open so that the coarse piece can pass through the fine breaking mechanism and reach the discharge  23  provided for fine chips and coarse chips. A drive unit  26 , which may comprise an electrical, hydraulic or pneumatic drive motor, is provided for opening the stationary tooth bearing segments of the fine breaking mechanism. 
     Alternatively, a control signal for opening the stationary tooth segments of the fine breaking mechanism can be generated in response to an overload condition of the motor determined by monitoring motor torque or the higher current consumption of the motor. 
     FIG. 2 shows an embodiment of the invention in which the stationary parts of the fine breaking mechanism are divided into two segments  29  and  30 . Segments  29 ,  30  can be moved outwardly apart from one another, thus opening a very large cross-section through the crushing device, so that even larger coarse pieces can pass without hindrance to the discharge provided for fine cuttings and coarse pieces. 
     FIG. 3 shows a further embodiment in which the stationary teeth of the fine breaking mechanism are distributed over three toothed segments  31 ,  32  and  33 , which can also be moved outwardly, thus opening a passage for coarse pieces which enter the fine breaking mechanism. 
     The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations falling within the scope of the appended claims and equivalents thereof.