Abstract:
A frame ( 10 ) carries two fixtures ( 16, 20 ), of which at least one ( 20 ) is movable, and which have respective crescents ( 18, 22 ) adapted to be brought together to form a circular profile engageable with the big end of a connecting rod and separable by opening means for fracturing the big end of the connecting rod. The apparatus also has transfer means ( 58 ) for transferring a connecting rod from a rod conveyor line ( 12 ) to said crescents ( 18, 22 ) and vice versa; an actuator ( 60 ) for pressing a locking member ( 62, 162, 262 ) against portions of the rod body in order to lock the rod body against the crescent facing the body; another actuator ( 64 ) for pressing a profiled block ( 66 ) against the other end of the connecting rod in order to lock it against the crescent proximate to the cap; an auxiliary actuator ( 23, 25 ) for remating the cap with the body of the rod; and ejector means ( 68, 70, 72 ) for ejecting the connecting rod from the crescents and for returning it to the transfer means after its fracturing and remating.

Description:
BACKGROUND OF THE INVENTION 
     This invention is concerned with an apparatus for separating the bearing caps of connecting rods by fracture, with subsequent remating of the parts and screwing of the union bolts. The process is suitable for connecting rods having either a cracking plane that is at right angles or that is askew to the body of the connecting rod. 
     Separation of the cap from the body of the connecting rod by fracture has been known for several years. More particularly, IT-A-1.268.130 describes a process and apparatus for implementing the separation of the cap from the body of a connecting rod in a way that minimizes deformation of the workpiece caused by yield stress, i.e. in a way that gives rise to a so-called fragile fracture. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is now to provide an apparatus that improves the process and the apparatus of the above prior patent, more particularly by automating the entire operating cycle. 
     Another object is to provide an apparatus having a high flexibility of operating conditions, so that the apparatus can be readily adapted to fracture connecting rods of different materials, shapes and sizes. 
     The invention achieves the above and other objects and advantages, such as will appear from the following disclosure, with an apparatus for separating the bearing cap of a connecting rod by fracture having the essential features set out in claim 1. 
     The dependent claims define other advantageous features of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be further described with reference to a preferred embodiment, which is illustrated, by way of nonlimiting example, in the attached drawings, wherein: 
     FIG. 1 is a diagrammatic, cross-elevation view of an apparatus for separating the bearing cap of a connecting rod by fracture according to a preferred embodiment of the invention; 
     FIG. 2 is a plan view of the apparatus of FIG. 1, in cross-section made along plane AA; 
     FIG. 3 is a view, on an enlarged scale, of a central portion of FIG. 1; 
     FIG. 4 is a detail view, in cross-section, in the direction of arrow B on FIG. 1; 
     FIG. 5 is a detail view, in cross-section, in the direction of arrow C on FIG. 1; 
     FIG. 6 is a view similar to FIG.  2 . concerning a first variation of the apparatus; 
     FIG. 7 is a view similar to FIG. 2, concerning a second variation of the apparatus; and 
     FIG. 8 is a diagram of a hydraulic circuit controlling a hydraulic actuator which is part of the invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 to  5  of the drawings, the apparatus of the invention comprises a stationary, portal-shaped frame  10  extending transversely above a pair of transfer bars, known per se, and provided, at uniform intervals, with seats or blocks for accommodating a connecting rod  14  having a bearing cap. 
     Frame  10  supports a stationary fixture  16  comprising a massive body extending downwardly to form a stationary, semicircular crescent  18 , and a movable fixture  20 , also comprising a massive body extending downwardly to form a movable, semicircular crescent  22 . The two crescents are arranged in mirror positions with respect to their flat sides, and at right angles to the direction of motion of the movable fixture, so that a circular profile is generated. 
     Movable fixture  20  is slidable along two horizontal guides  24  (FIGS. 2,  4  and  5 ) which are integral with frame  10 , and is driven by a hydraulic actuator  23 , mounted on the frame, through a rod  25 , and having the main task of bringing back together the movable crescent to the stationary crescent after fracturing the cap, as well as other accessory tasks as explained below. 
     Having now more particular reference to FIGS. 3,  4  and  5 , the flat side of stationary crescent  18  has a chamber  26  within which a piston  28  is sealingly slidable. Piston  28  has a hemispheric crown, is provided with sealing rings  29 , and is integrally mounted on the flat side of movable crescent  22 , to form a hydraulic actuator for spreading or prying open the crescents. Stationary crescent  18  also contains a vertical, cylindrical reservoir  30  for hydraulic fluid, within which a piston  32  is sealingly slidable, and which is linked to chamber  26  through a conduit  34 . Around the piston-mounting area, the surface of crescent  22  has a groove or annular chamber  35 , which is externally enclosed by a lip seal  37  abutting against a ridge on crescent  22  so that it defines a collection chamber for any hydraulic fluid leaking from piston  28 . 
     A turret  36 , rising from frame  10 , accommodates a hydraulic cylinder  38 , which is supplied with pressurized hydraulic fluid from a source not shown. Piston  40  of cylinder  38  has a rod  42  facing downwardly, in alignment and in abutment with piston  32 , so that both pistons  32  and  40  form together a pressure multiplier the ratio between the cross-section areas of pistons  32  and  40  is preferably in the range 10:1 to 25:1. 
     Piston  40  also has a rod or projection  44 , facing upwardly and arranged to receive the impact of a ram  46 , which is slidable in a vertical guide  48 . Ram  46  is normally held by a retaining tooth  50 , driven by a hydraulic actuator  52 , and the fall of the ram is assisted by a spring  54 , so that ram  46 , when released from tooth  50 , is imparted a sharp initial acceleration toward projection  44 . After the fall, ram  46  is returned by means of a hydraulic actuator  56 , so that it is primed again by hooking on tooth  50 . 
     A jack  58  is arranged to rise from beneath shifting bars  12 , under control of an actuator not shown, to engage a connecting rod  14  and lift it off transfer bars  12  to a work position where the big end of the connecting rod is pushed around crescents  18  and  22 . 
     Frame  10  also supports a first locking device comprising a hydraulic actuator  60  which controls, via a non-reversible lead screw, a V-shaped block  62 , slidable along guides  63 , and arranged for pressing on the small end of connecting rod  14  and therefore to lock the rod body against the stationary crescent. 
     Movable fixture  20  carries a second locking device, also comprising a hydraulic actuator  64  arranged for pressing both ends of a pivoting rocker  66  against the bolt seats on the bearing cap of the connecting rod, so that the latter is locked against the movable crescent. 
     Frame  10  also carries a rod ejector comprising a pusher  68  driven by an actuator  70  through a toggle lever  72 . 
     The apparatus comprises a further advantageous device, comprising a dust blower system to blow the dust that may be generated in the fracture, and comprising two oblique conduits such as  74  (FIGS.  3  and  5 ), which can be connected to a source of pressurized air not shown. The conduits are parallel and oblique, and are drilled in the body of movable fixture  20 , and they lead to blower nozzles  76  on the flat side of the movable crescent. 
     Finally, the apparatus also comprises a draining conduit  78 , drilled in the body of the movable fixture, leading from annular chamber  35  to a nipple  79  which is connectable to a suction pump (not shown) for withdrawing the hydraulic fluid leaks accumulating in chamber  35 . 
     In operation, while crescents  18  and  22  are close together and the ram is primed, bars  12  bring a connecting rod  14  in position beneath the above described apparatus. Jack  58  lifts the connecting rod until its big end is pushed around the crescents. Actuator  60  is then driven to engage V-shaped block  62  on the little end, and a moderate pressure is applied to hydraulic actuator  23 , in order to lock the big end of the connecting rod, and finally actuator  64  is operated to press rocker  66  against the bearing cap. Both the body and the bearing cap of the connecting rod are therefore locked independently from each other, respectively between block  62  and stationary crescent  18 , and between movable crescent  22  and rocker  66 . 
     The pressure in cylinder  23  is now increased, so that the resisting sections between the cap and the body of the connecting rod are pretensioned up to a load slightly lower than the yield stress  46  is now released, in order to apply a pressure peak through the pressure multiplier, such that the cap&#39;s breaking stress is rapidly exceeded. The bearing cap is therefore separated from the body of the connecting rod, the movable crescent being quickly moved away from the stationary crescent. 
     A scouring jet of compressed air is now blown through nozzles  76 , in order to clean the fractured surfaces from any dust and loos debris. Ram  46  is then primed by pressurizing the lower chamber of cylinder  56  until tooth  50  is hooked again. The bearing cap is remated to the body of the connecting rod under high pressure by means of actuator  23 , the crescents being brought back to their initial positions. The clamps formed by V-shaped block  62  and by rocker  66  are then released, so that connecting rod  14  is freed and is then pushed by ejector  68  and by jack  58  until it rests on bars  12 , for transportation to the subsequent processing, more particularly to a subsequent screwing station not shown. 
     In order to have a braking action to the travel of the movable fixture when the peak of fracturing pressure is applied, a moderate pressure is applied to the back chamber of actuator  23 , such that it will not affect the quickness of the fracture, but such that it will present a braking resistance to the travel of the movable crescent after it has been freed by the fracture, by controlling the outlet flow of oil from the back chamber. Alternatively, in order to improve the durability of the device, actuator  23  may also be used to contribute to the fracturing force, by controlling the pressure values in the forward chamber. 
     FIG. 8 diagrammatically shows a hydraulic circuit for controlling hydraulic actuator  23 , in order to implement both the function of cap pretensioning and the function of braking and damping the travel of the movable fixture after fracture, as well as the function of remating the crescents. From a source of hydraulic pressure applied to  80 , the circuit splits into a first line  81  feeding the forward chamber of actuator  23  through a pressure-reduction valve  82  and a four-way, two-position electrovalve  83 , and a second line  84  leading to the back chamber of actuator  23  through a fixed-setting flow regulator  85  and a gauged throttle  86 . From the junction of regulator  85  and throttle  86 , a conduit  87  leads to drain through a non-return valve  88 , set to constant pressure. Finally, the valve  83  is switched, the pressure supply goes to the back chamber of actuator  23  through a second non-return valve  89 . 
     The fracturing cycle is started with electrovalve  83  in the position shown. By applying pressure  80 , the forward chamber of actuator  23  (up on FIG. 8) is pressurized, so the pretensioning is created between the cap and the body of the connecting rod, while, at the same time, the back chamber of actuator  23  is also moderately pressurized through line  84 . After dropping the ram and separating the cap, the hydraulic fluid contained in the back chamber tends to flow through conduit  87 , though it is hindered by throttle  86  and consequently slows down the travel of the movable fixture. After the movable fixture has stopped, electrovalve  83  is switched to pressurize th back chamber of actuator  23 , discharging its forward chamber, so that the cap of the connecting rod is brought back to be remated with the body. After the connecting rod has been ejected and the next connecting rod is loaded, electrovalve  83  is switched back to its initial position as shown. 
     With reference to FIG. 4, the pressure multiplier is also provided with a device to compensate any fluid losses which may arise from leaks, and comprising a conduit  90  joining into conduit  34  from a connector  92 , and including a ball check valve  94 . This arrangement allows the fluid to be topped up without interfering with the operation of the device. Instead of plug  96 , a probe (not shown) can be inserted to monitor the pressure changes. 
     FIG. 6 shows a variation of the fracturing device, intended for connecting rods where the fracturing plane is required to be oblique rather than at right angles to the rod body. The device is substantially similar to the one disclosed above, except that V-shaped block  62 , clamping the little end, is replaced with a profiled block  162 , gauged for pressing with a balanced pressure on the side of the connecting rod. 
     FIG. 7 shows another variation, where V-shaped block  62  is replaced with a U-shaped block  262 , having two eleongated arms  262 ′,  262 ″ straddling the rod body and abutting against opposite sides of the big end. By this arrangement, the rod body is left unloaded and the elastic behavior of the body does not affect the dynamic system, avoiding possible undesirable effects. Within the spirit of this approach, actuator  60  and block  62  or  262  might be replaced with a pair of cylinders (not shown) abutting on the big end, either directly or through an irreversibility device. Actuator  64  and rocker  66  might also be replaced with a pair of wedge-shaped members (not shown) having equal inclinations and having independent feeding motions, whereby, when they travel at right angles to the fracturing surfaces, they clamp the connecting rod against their respective crescents through the movable members of the big ends. The identical angles of the wedge-shaped members give rise to a smooth travel and a uniform clamping of the big end. 
     Obviously, a number of other changes can be made to the preferred embodiments as described above, within the teachings of the invention. For instance, although the preferred embodiments provide one movable crescent and one stationary crescent, both crescents might be movable, or alternatively, the crescents might be switched, the crescent associated with the rod body being movable and the crescent associate with the bearing cap being stationary. Moreover, as a way of braking the movable member, conventional stopper devices might be used, as known in the art, instead of a counterpressure in actuator  23 . Further, although the arrangement where the connecting rod is horizontal and is lifted from below, according to the embodiments disclosed above, is preferable for ease of loading and unloading of the workpiece and also for ease of disposal of the chips and dust, nevertheless the apparatus might be designed so that the connecting rod is vertical or inclined, or horizontal but loaded from above, with suitable changes in the devices, such as will be obvious for the person skilled in the art. Finally, several of the actuators disclosed in the description might be implemented differently from the examples shown, and in particular they might be mechanical rather than hydraulic. 
     The disclosures in Italian Patent Application No. TO99A000780 from which this application claims priority are incorporated herein by reference.