Abstract:
A device for separating the rod and cap of a connecting rod by breaking includes a fixed expansion mandrel half on a fixed device part a mobile expansion mandrel half on a device part which moves in the direction of expansion, and support elements for the rod and the cap. The device has a long service life without operational problems and can separate the rod and cap of a connecting rod from each other with a high degree of precision. To this end, the adjustable support elements are arranged on the fixed device part and the fixed support elements are arranged on the mobile device part.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for crack splitting a rod (shaft) and a big-end cap of a connecting rod, including a fixed expander mandrel half on a fixed part of the apparatus, a movable expander mandrel half on a part of the apparatus movable in the expanding direction and including supporting elements for rod and cap. 
     2. Description of the Related Art 
     Known from European patent document no. EO 0 396 797 is an apparatus for crack splitting rod and cap, including advanceable supporting elements on both the movable and fixed parts of the apparatus. In this known art, the advanceable supporting elements are formed by set screws (illustrated symbolically as grub screws). Turning the set screws permits advancing the supporting elements to clamp the connecting rod to be split relative to the fixed and movable expander mandrel halves in the apparatus. Experience has shown that clamping in place the connecting rod to be split, especially to prevent it from turning out of place, is necessary to achieve a defined crack with no negative bending effects. 
     With the advanceable supporting elements, it is also possible to set the apparatus for crack splitting rod and cap of connecting rods of various sizes. In addition, with the advanceable supporting elements, differences due to manufacturing tolerances can also be compensated for. 
     To achieve speedy adaptation, it is known to use powered advanceable supporting elements. In the case of both manual set screws and powered advanceable supporting elements, there is the problem that the advanceable supporting elements provided on the movable part of the apparatus are exposed to shock and vibration that is inherently involved in the crack splitting. Thus, in splitting, the two expander mandrel halves are usually urged apart with the aid of a cleaving wedge. This movement and splitting of the cap from the rod occurs abruptly. In addition, the movable part of the apparatus impacts a stop at which the movement of the movable part of the apparatus is halted. Powered advanceable supporting elements are especially heavily stressed by this action, resulting in problems with proper functioning and long useful life. 
     SUMMARY OF THE INVENTION 
     The present invention provides an apparatus for crack splitting the rod (shaft) and big-end cap of a connecting rod. The apparatus has a long useful life with no functioning problems. With the apparatus, the rod and the big-end cap of a connecting rod can be split with high precision. The advanceable supporting elements are arranged on a fixed part of the apparatus and the fixed supporting elements are arranged on the movable part of the apparatus. 
     In the present invention, the advanceable supporting elements, automatically exposed to more stress, are provided on the fixed part of the apparatus to thus significantly reduce the problems involved in reliable functioning and long useful life. This is particularly important where use is made of powered advanceable supporting elements, which are usually powered by pneumatic or hydraulic cylinders or by electric motor drives which are not only in themselves sensitive to shock and vibration but also incorporate flexible input and output tubing for supply and control. Flexible input and output tubing in pneumatic, hydraulic or electric motor drives are particularly sensitive to shock and vibration and cyclic stresses of reciprocating operation. Arranging these sensitive parts on the fixed part of the apparatus in accordance with the invention avoids the resulting loads and at least the influence of direct shock and vibration which is particularly damaging to flexible tubing and electric wiring. 
     Since the big-end caps of connecting rods always need to have outer contact surface areas for the bolts for connecting rod and cap, the cap can be supported particularly effectively at these contact surface areas. In one embodiment of the present invention, the fixed part of the apparatus is equipped to mount the cap and the movable part of the apparatus is equipped to mount the rod. In this arrangement, the rod is held particular simply and effectively in the apparatus when at least one fixed supporting element is formed by a locating peg for mounting the small-end bore of the rod. 
     As an alternative, the fixed supporting element may also be formed by a recess at least partially contacting suitable portions of the outer surface area of the rod end (small-end). 
     One particularly effective feature of the advanceable supporting elements is that they contact at least one shiftable wedge element substantially transversely to the advance movement. Such an arrangement enables a particular rigid arrangement to be achieved for loading. Advantageously in this arrangement, two supporting elements are provided and a wedge element is assigned to each supporting element. Thus, it is possible to benefit from the advantages of wedge actuation whilst simultaneously clamping the connecting rod reliably in place at two opposite locations. 
     By adapting the advance movement of each supporting element to uniformly clamp in place the connecting rod to be split, both wedge elements include wedge surface areas having an identical angle of attack. This thus achieves for both supporting elements an identical advance movement in such a configuration when both wedge elements are shifted by the same amount. 
     Production tolerance inaccuracies on the part of the connecting rod to be supported can be compensated for in that two advanceable supporting elements are provided, each of which can be advanced independently of the other. Due to the two supporting elements, each advanceable independently of the other, each connecting rod part to be fixedly secured can be individually set. 
     Auto-centering by actuating the wedge elements is simply achieved in that the wedge surface areas of the wedge elements are arranged opposite in angle of attack. Further, a hydraulic or pneumatic cylinder is provided whose face cooperates with the one wedge element and whose piston cooperates with the other wedge element. However, a particularly effective actuation of the advanceable supporting elements is also achievable by direct-acting hydraulic cylinders. This enables each supporting element in such a case to be connected to the piston rod of a supporting piston. This connection is configured to advantage such that each of the supporting elements may be arranged directly at the front end of the piston rod of the pistons. 
     For loading the connecting rods into the crack splitting apparatus, a loading device holds the crack splitting apparatus substantially stationary whilst the connecting rods are inserted therein. In such a configuration, the pneumatic or hydraulic cylinders or the electric motor drives including the feed and discharge lines for supply and control can be stationary whilst loading is achieved exclusively by moving the connecting rod. 
     There are basically two possibilities available for the loading arrangement. In the one possibility, a transport device may be arranged above the stationary apparatus for overhead insertion/removal of the connecting rod into/from the apparatus. In the other possibility, a clocked transport device is provided under the stationary apparatus from which the connecting rod is picked out for insertion into the apparatus, held in the apparatus during crack splitting, and then lowered back into the transport device. 
     To protect the sensitive drive system including the feed and discharge lines from indirect shock and vibration, the apparatus is mounted on a baseframe via shock absorbers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention will now be detailed for further explanation and a better understanding of the invention with reference to the attached drawings in which: 
     FIG. 1 is a schematic, partially sectioned plan view of a first embodiment of the apparatus in accordance with the invention; 
     FIG. 2 is a schematic, partially sectioned detail view of a second embodiment of the apparatus in accordance with the invention; 
     FIG. 3 is a schematic, partially sectioned plan view of a third embodiment of the apparatus in accordance with the invention; and 
     FIG. 4 is a schematic, partially sectioned plan view of a fourth embodiment of the apparatus in accordance with the invention. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is illustrated the first embodiment of an apparatus in accordance with the invention including a movable part  2  and a fixed part  4  of the apparatus. The movable part  2  of the apparatus is guided longitudinally on a frame  8  via guides  6 , shown schematically, so that the movable part  2  of the apparatus reciprocates on the frame  8  like a slide. The frame  8  as well as the fixed part  4  of the apparatus are held secured in place on a common baseframe  9  via shock absorbers  11 . 
     Arranged above the apparatus is a transport device  13  for inserting the connecting rods  12  into the apparatus from above and for removing them likewise from above. Alternatively, or additionally, a clocked transport device  15  is provided under the apparatus from which the connecting rods  12  are lifted for insertion into the apparatus, held in the apparatus during crack splitting, and then lowered back into the transport device  15 . 
     Retained in the movable part  2  of the apparatus is a rod  10  of a connecting rod  12  to be split. For this purpose, the movable part  2  of the apparatus includes a substantially flat retaining surface area  14  on which the connecting rod  12  rests. Furthermore, the movable part  2  of the apparatus includes a supporting element, which in this case is configured as a V-block  16  (prism holder) whose retaining surface areas are at least partly in contact with the outer surface area of the connecting rod small-end of the rod  10 . As an alternative, the rod  10  may be locked to prevent it from turning out of place by a fixed pin or peg  17  protruding into the small-end bore of the connecting rod. As another alternative, the supporting element may be in the form of a recess  19  (FIG. 4) contacting portions of the outer surface of the small-end of rod  10 . 
     Engaging a bore  18  of the connecting rod  12  are two expander mandrel halves  20 ,  22 . The expander mandrel half  20  is secured to the movable part  2  of the apparatus and protrudes beyond the retaining surface area  14 . Accordingly, the connecting rod  12  to be split is retained in the region of the rod, on the one hand, by the V-block  16  protruding beyond the retaining surface area  14  and, on the other hand, by the expander mandrel half  20 . 
     On the fixed part  4  of the apparatus, the connecting rod  12  to be split is clamped in place between the expander mandrel half  22  and two advanceable supporting elements which are spaced away from each other. In the present example, the supporting elements are formed by two pins  24  guided in the longitudinal direction of the connecting rod  12  to be split. As evident from FIG. 1, the two pins  24  engage the surface areas of a big-end cap  26  of the connecting rod  12 . These contact surface areas are needed in later assembly of the connecting rod  12  for joining rod and big-end cap together for contacting the heads of the tie-bolts. 
     It is evident from FIG. 1 that the big-end cap  26  of connecting rod  12  is clamped in place merely between the expander mandrel half  22  and the two pins  24 . The fixed part  4  of the apparatus includes in the region of the cap  26  a recess  28  into which the big-end cap  26  of the connecting rod  12  can be easily inserted when the pins  24  are retracted. 
     Whilst the front face of the advanceable pins  24  is in contact with the cap  26 , the rear ends of the pins  24  are flared into respective contact pieces  30 . Each contact piece  30  contacts a wedge element  32  via its wedge surface area  33 . Each wedge element  32  is shiftingly held in a recess  34  oriented substantially perpendicular to the longitudinal axis of the connecting rod  12  and supported at the surface of the recess  34  relative to the fixed part  4  of the apparatus. Each wedge element  32  cooperates via a piston rod  36  with a double-ended hydraulic cylinder  38 . 
     To split the big-end cap  26  from the rod  10  of a connecting rod  12 , connecting rod  12  is mounted by its bore  18  on the adjoining expander mandrel halves  20 ,  22 . In this arrangement, the connecting rod  12  is oriented so that the outer surface area of the rod-end is inserted in the V-block  16 . After this, the connecting rod  12  is clamped in place. For this purpose, the hydraulic cylinders  38  are energized so that the two wedge elements  32  are moved towards each other. The contact pieces  30  slide on the inclined wedge surface area  33 . This results in the guided pins  24  being advanced in the direction of the connecting rod  12 . Due to the connecting rod  12  being defined between the V-block  16  and the two expander mandrel halves  20 ,  22 , the connecting rod  12  is arranged such that the front faces of the pins  24  are urged against the contact surface areas of the big-end cap  26 . 
     To uniformly clamp the connecting rod  12  in place between the expander mandrel half  22  and the pins  24 , the hydraulic cylinders  38  can be energized individually. By sensing the internal pressure in each hydraulic cylinder  38 , the force with which each pin  24  is urged against the cap  26  can be controlled. This makes possible a uniform clamping in place of the connecting rod  12 . 
     Once the connecting rod  12  has been inserted into the apparatus and clamped in place via the pins  24 , the actual splitting follows, as is known. For this purpose, a cleaving wedge  40  disposed between the expander mandrel halves  20 ,  22  is powered forwards to part the two expander mandrel halves  20 ,  22  from each other. On rupture of the joint between rod  10  and cap  26 , the movable part  2  of the apparatus distances itself from the fixed part  4  of the apparatus abruptly. This sudden movement is cushioned by spring stops  42  secured to the frame  8 . 
     The connecting rod, now split, can be removed from the apparatus. This first requires the wedge elements  32  to be retracted via the hydraulic cylinders  38  to release the tension on the cap  26 . After this, the rod  10  and the cap  26  can be lifted out of the apparatus either manually or automatedly. 
     Referring now to FIG. 2, there is illustrated a second embodiment of the present invention on a magnified scale. The embodiment as shown in FIG. 2 differs substantially from the embodiment as shown in FIG. 1 by the two wedge elements  32  being powered by a common hydraulic cylinder  44 . In the embodiment as shown in FIG. 2, the hydraulic cylinder  44  is fixedly connected to a wedge element  32 , whereas the other wedge element  32  cooperates with the hydraulic cylinder  44  by a piston rod  46  which penetrates the first wedge element and is connected to a piston  48  sealed in the cylinder  44 . 
     The two wedge surface areas  33  in the embodiment shown have an identical angle of attack relative to the sliding plane of the wedge elements  32 . In addition, the wedge elements  32  are disposed opposingly inclined relative to each other. 
     Advancing the pins  24  to clamp the big-end cap  26  in place results in the two wedge elements  32  being moved towards each other. This advance movement actuation is possible with the aid of just a single hydraulic cylinder  44 . Due to the geometry of the hydraulic cylinder  44 , a substantially identical advancing force acts on the two wedge elements  32 . In this arrangement, this simple design feature ensures that each of the two pins  24  is in contact with the cap  26  with identical force. 
     To release the tension on the cap  26  once it has been split from the rod  10 , the two wedge elements  32  are forced away from each other by actuation of the cylinder  44 . Stops (not shown) defining this movement of the wedge elements  32  prevent one wedge element  32  being shifted whilst the other wedge element  32  remains in place. This thus ensures that both pins  24  are distanced from the expander mandrel half  22  to make room for inserting a new connecting rod. 
     Referring now to FIG. 3, there is illustrated a third embodiment including supporting elements  24  in the form of pins, each arranged directly at the front end of the piston rods  50  of hydraulic supporting pistons  51 . The positioning of the pistons  51  is sensed by a sensor device  52  indicated only schematically in FIG.  3 . The pistons rods  50  and the pistons  51  are mounted in a cylinder housing  53  arranged on the fixed part  4  of the apparatus. 
     During crack splitting, the supporting elements  24  are maintained in contact with the big-end cap  26  of the connecting rod  12  by a controlled hydraulic pressure. Retraction of each supporting element  24  during crack splitting is assured by a separate controlled check valve  54  sealingly arranged on the cylinder housing  53 . 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.