Abstract:
This patent relates to a system for rotating work pieces about a horizontal center line so that one or more sides can be machined with out the need of re-clamping. Pallets or log pallets may be used for holding work pieces so the pallets with work pieces can be removed from the machine for parts handling or set-up. Related improvements are described: A rotary table that reduces angular error caused by off center weight, protection from damage caused by inadvertent crash impact, protection from pallets falling from inadvertent unclamping and improved cleaning of pallet locating surfaces. An off machine parts loading index station that prevents inadvertent release of the pallet and provides the optimum ratio between the manual crank and the pallet rotation. A powered actuator that can be used with means for transferring pallets between the machining center and index stations or index and support stations that are mounted to mobile carts.

Description:
[0001]    This patent relates to a Provisional patent application filed Jul. 24, 2007. (Application No. 60/961,827) 
     
    
     BACK GROUND OF THE INVENTION 
       [0002]    The Utility patent application is the same as the Provisional Application with the exception of improved drawings and description. 
         [0003]    This invention relates to the improvements needed to provide a machining system that rotates work pieces around a horizontal center line for machining. This system may be adapted to commercial machining centers. 
       DESCRIPTION OF PRIOR ART 
       [0004]    Horizontal machining centers are normally used to rotate work pieces around a vertical centerline. Their spindle rotates around a horizontal center line. A structure shaped like a tombstone is fixed at one end. It is rotated to expose all sides to the spindle. Work pieces are mounted to vertical the sides of the tombstone for machining. All motion of a machining center, X, Y, Z and rotary axis is controlled by a special computer that can be programmed to machine work pieces. The features of a part can be machined with little or no operator intervention. 
         [0005]    Work piece loading and un-loading is normally accomplished by an operator. System rigidity, accuracy and ease of work piece loading and un-loading is a fundamental need. 
         [0006]    Tombstones are supported at one end. Logs are supported at both ends. Compared to a tombstone supported at one end a log supported at both ends is 35.8 times more rigid. While it is easy to support both ends of a horizontal log, it is very difficult to support both ends of a log or tombstone when rotated about a vertical centerline. 
         [0007]    Logs and tombstones may be attached to devices called pallets that can be removed from the machining center for work handling or other reasons. 
         [0008]    A horizontal log pallet system was developed and marketed by the inventors of this invention. This system consisted of a rotary table with means for clamping a pallet and a tail stock for supporting one end of a log pallet. An index station was developed for manual off machine pallet indexing to facilitate work piece loading and un-loading. The pallets were manually transferred from a cart supported index station and log support station, across a gap to a rotary table and tail stock. 
       SUMMARY OF THE INVENTION 
       [0009]    This invention relates to an improved rotary table, pallet rotary table, tail stock, index station and a powered on/off actuator and a powered pallet rotary table bridge extender. Inter locks are included to prevent inadvertent pallet dropping from the pallet rotary table and index station. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an overall view of a pallet rotary table system including an on/off pallet actuator and tail stock. 
           [0011]      FIG. 2  shows a cart with an index station, support station and a log pallet. 
           [0012]      FIG. 3A  shows a front view of a pallet rotary table with partial sections of a worm back lash removal system. 
           [0013]      FIG. 3B  shows a section taken thru  FIG. 3A  showing means for rotation, pallet clamping and a split shaft worm gear locking device and means for resisting inadvertent crash impact. 
           [0014]      FIG. 4  shows a partial section of a tail stock engagement used to support one end of a log pallet. It shows a partial section of the tail stock taken thru  FIG. 1   
           [0015]      FIG. 5A  shows a front view of an index assembly. 
           [0016]      FIG. 5B  is a partial section showing interlocks that prevent inadvertent release of a pallet from the index assembly. 
           [0017]      FIG. 5C  shows the crank side of the index station. 
           [0018]      FIG. 6A  shows a partial view of gears used to increase the angular ratio between the crank and pallet. 
           [0019]      FIG. 6B  is an end view of  FIG. 6A   
           [0020]      FIG. 7A  shows a pallet on/off actuator in its retracted position and engaged to a pallet that has been un-clamped from a pallet rotary table. 
           [0021]      FIG. 7B  shows the extended on/off actuator. 
           [0022]      FIG. 8A  shows a section of the on/off actuator taken thru  FIG. 8C   
           [0023]      FIG. 8B  shows a section taken thru  FIG. 8C . 
           [0024]      FIG. 8C  is a top view of the on/off actuator. 
           [0025]      FIG. 9A  shows an on/off actuator in its retracted position and engaged to a flat pallet. 
           [0026]      FIG. 9B  is a partial view of a pallet clamp with the pallet removed and the on/off pallet actuator extended. 
           [0027]      FIG. 10A  shows a pallet rotary table bridge with two extensions, one for closing a gap between the rotary table bridge and an index station and the other to align the index station with the rotary table bridge. 
           [0028]      FIG. 10B  shows a front view of  FIG. 10A   
           [0029]      FIG. 10C  is a side view of  FIG. 10B  showing an air or hydraulic cylinder used for actuating the extensions. 
           [0030]      FIG. 11A  is an end view showing A roller rail extension combined with a tail stock. 
           [0031]      FIG. 11B  is a front view of  FIG. 11A . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0032]    For the purposes of promoting an understanding of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated devices, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0033]    This invention relates to a system that can be used with a machining center  FIG. 1  for rotating work pieces, pallets  1  or log pallets  2  about a horizontal centerline so that work pieces fixed a platen or to one or more sides of a pallet or log pallet can be machined on one or more sides. 
         [0034]    A pallet rotary table supports a pallet  1  or log pallet  2  at one end and accurately rotates it as controlled by the machining center computer axis drive motor. The pallet rotary table  3  is provided with a system for powerful and accurate clamping and unclamping a pallet so it can be removed from the machining center for various reasons. 
         [0035]    A tail stock  4  supports the log at the end opposite the pallet rotary table. A bridge  5  is used to support the pallet during pallet transfer to and from the pallet rotary table. The bridge and a roller rail  6  is used to support a log pallet at both ends for transfer to and from the machining center to a cart. 
         [0036]    The cart  8   FIG. 2  may be laterally (Y AXIS.) fixed to the machining center but free to move along a longitudinal (X) axis and held at certain locations to receive a pallet or log pallet from the machining center. The cart is easily decoupled from the machining center and moved to any location for work piece handling, set-up or storage. Pallet transfer to and from the cart may be manual or by an on/off actuator  7   FIG. 1 . One or more index stations  9  may be located on the cart  8  for receiving a pallet and rotating or indexing it about a horizontal centerline to provide operator access to all sides of the pallet for work piece handling. One or more support stations  10  may be positioned on the cart to support the end of a log pallet. 
         [0037]      FIG. 3B  A rotary table consists of a shaft  11  rigidly supported by ball bearings  12  and  13 . One end of the shaft consists of a structure called a platen  14  which may be adapted to hold work pieces or clamp pallets to. 
       Description of Improvements 
       [0038]    The rotary table is provided with a separate base  17 . This facilitates the inclusion of customized bases most suitable for various machining centers. 
         [0039]      FIG. 3A  A brake is used to increase angular rigidity after rotary motion has stopped. An earlier designed brake consisted of an air piston that engaged the outer diameter of the worm and forced it against the worm gear to remove backlash and resist rotary motion of the worm gear. 
         [0040]    An improved brake applies air piston  18  force against a long extension  19  of the worm shaft in order to create leverage that increases the brake force. The smaller diameter of the extension reduces angular error caused by contact by the actuating piston  18 . Angular force and thus angular error caused by the piston contact with the smaller diameter shaft extension  19  is reduced by the ratio of the diameters of the larger worm and the smaller extension shaft. 
         [0041]      FIG. 3B  Air is supplied to the front side of the clamp piston  23  to add to the spring force used to clamp a pallet against four seats  28 . 
         [0042]    Cleansing the seats  28  was improved by providing sufficient air pressure on the back  24  side of the clamp piston to exceed the spring force and air pressure force against the front side of the clamp piston to unclamp the pallet. This causes the air on the front side of the piston to rapidly exhaust between the seats as they separate. The large volume of air flowing thru the large seat separation area creates a high velocity, large volume of air that is very effective for removing contamination around the seat area. This assures accurate relocation of the pallet. 
         [0043]      FIG. 3B  A locking device or shot pin is used to prevent rotary motion every 90 degrees. This is used as a quadrant reference and increases angular rigidity and angular accuracy at those locations. The locking device consists of a split shaft  20  that advances thru a bushing  22  and engages matched tapers of a tapered block  21 . This causes the split shaft  20  diameter to expand against the inside of the bushing  22  in order to remove all clearance. 
         [0044]    This was improved by allowing the tapered block  21  to slide with respect to the worm gear  15  at a predetermined force to prevent rotary table angular crash impact damage. The tapered block  21  is bolted, not pined, to the worm gear  15 . Openings are provided in the rotary table housing to provide access for convenient re-adjustment of the tapered block  21  while the split shaft is engaged, to assure accurate adjustment. 
         [0045]    Further improvement enabled impact energy to be absorbed by slippage between the shaft  11  and worm gear  15 . This can occur at any angular position of the rotary table. The worm gear  15  is bolted to the shaft  11 , not pined so predetermined force can cause slippage. Openings are provided in the rotary table housing to provide access for the worm gear adjustment while the split shaft  20  is engaged with one of the tapered blocks  21  to assure accurate adjustment of the worm gear. The predetermined slippage force is controlled by the torque applied to the tapered block  21  and worm gear  15  fasteners. 
         [0046]    The pallet rotary table clamps the pallet against four seats  28  that are accurately located on the platen  14 . Air and spring pressure are used on the front side of the clamp piston  23  to clamp the pallet. Air pressure that is used to unclamp the pallet is applied to the back side  24  of the piston  23 . 
         [0047]    This was improved by routing the unclamp air flow thru two holes  25  that are only aligned to transmit air when the top surface of the pallet clamp  26  is horizontal and it is safe to unclamp the pallet with out it falling from the rotary table. 
         [0048]      FIG. 5A  Shows an index station  9 , located on a cart  8   FIG. 2  for manually rotating or indexing a pallet for off machine work parts handling. A pallet transfer lock pin  40  engages the pallet  1  to prevent the pallet from sliding off the rail  41 . When the rail  41  is rotated beyond a certain angle, the pallet transfer lock pin  40  prevents gravity from causing the pallet  1  to fall from the rail  41 . Failure to engage the pallet transfer lock pin  40  when the rail is rotated could be hazardous to personnel and equipment. A rotational lock pin  42  is used to stop the rail rotation. Manual rotation is accomplished by disengaging the rotational lock pin  42  by impacting it with the lever  43  to extract it from the lock ring  44  and thus enable rotation of the rail  41  to the desired location. The rotational lock pin is re engaged by reverse action of impacting it with the lever  43 . 
         [0049]    This was improved by providing a Linkage  45  between the pallet transfer lock pin  40  and the rotational lock pin  42  so that the pallet transfer lock pin  40  must be engaged with the pallet if present, before the rotational lock pin  42  can be disengaged from the lock ring  44  in order to rotate the rail  41 . Thus, rotation is accomplished by grasping the crank  46  handle  56  with one hand and axially moving it to disengage the rotational lock pin and then rotating it to the desired location then re engaging the rotational lock pin by axial motion of the handle. 
         [0050]    This is further improved by providing a second interlock to prevent the operator from inadvertently retracting the pallet transfer lock pin  40  when the pallet could fall from the rail  41 . The pallet transfer lock pin  40  is attached to a piston  47  that is located in a bore provided by the hub  48 . Two pins  49  are located by the piston  47 . These pins  49  must project thru holes located in the hub  48  and align with holes located in the fixed structure of the tail stock  50  when the pallet transfer lock pin is disengaged from the pallet. This can only occur when the rail  41  is rotated to a horizontal position. Only then can the pallet transfer lock pin be retracted and the pallet be transferred from the rail  41 . 
         [0051]    Automatic means may be used for disengaging the pallet transfer lock pin  40  and releasing the pallet for transfer. 
         [0052]      FIG. 5B  shows a section of the index station with the pallet transfer lock pin  40  disengaged so that the pallet can be transferred to or from the machine. The pallet transfer lock pin must be disengaged and held against spring pressure to release the pallet. 
         [0053]    The piston  47  may disengage the pallet transfer lock pin by compressed air passing thru holes  52  and acting on the piston  47  when the rail  41  is in a horizontal position. This is required in the automatic pallet switching mode. Air can only be supplied to the piston  47  when the passages  52  are aligned when the top surface of the rail  41  is horizontal. 
         [0054]      FIG. 6  shows the application of gears  53 ,  54 , and  55  used to change the ratio between the hand crank and the rail  41 . This is necessary when very heavy or large pallets must be indexed. 
         [0055]      FIG. 7A  shows an on/off actuator used for transferring pallets  1  and or log pallet  2  to and from a machining center. The actuator is shown retracted and engaged to a pallet that has been unclamped from the rotary table. When the pallet is unclamped from the rotary table  3  it is moved away from the seats  28 , disengaged from the locaters  29  and the C-section  57  that is fastened to the pallet  1  is engaged with the—T-section  58  that is fastened to the on/off slide  59 . When pressure is applied to the hydraulic cylinder  61   FIG. 7  B it causes the guide bar  60  to extend beyond the on/off actuator base  62  which in turn causes the displacement of a flexible band  63  that causes the on/off slide  59  to extend an equal distance along the guide bar  60 . This causes the pallet  1  or log pallet  2  to move from the rotary table located on a machining center to an index station  9  that is located on a cart  8 ,  FIG. 2 . The on/off actuator must be short enough to fit within the machining center enclosure but provide sufficient travel to transport the pallet to a cart. When the pallet is on the cart, the T-section is disengaged from the C-section  58  by a small longitudinal displacement of either the cart or rotary table. Now the pallet is free to be rotated by the index station or be relocated by the cart. The pallet is transferred to the machining center and rotary table in a similar manner. 
         [0056]    The on/off actuator is further described by  FIG. 8A . A flexible band  63  is bolted  68  to a fixed bar  72  which is bolted  66  to the on/off actuator base  62 . The flexible band  63  wraps around rollers  64  located at each end of the on/off actuator base  62 . The rollers  64  are supported by bearings  65 . The flexible band  63  ends are bolted  68  to adjusting bars  67  that are bolted  66  to the under side of the on/off slide  59 . The adjusting bars are used to provide the flexible band  63  location and tensioning. The flexible band  63  slides in openings provided by the guide bar  60 . This excludes entrance of foreign matter from both sides of the flexible band into the on/off actuator. A hydraulic cylinder  70  is attached at one end of the on/off actuator base  62  and is attached at its rod end to the guide bar  60 . When the guide bar  60  is displaced by the hydraulic cylinder  70  the flexible band  63  causes the on/off slide  59  to travel a total distance of twice the travel of the guide bar  60 . This accounts for a long travel provided by a short actuator. Seals  71  and  73  are located at each end of the on/off actuator to exclude entrance of foreign matter at the entrance of the flexible band into the on/off actuator base. 
         [0057]      FIG. 9A  shows an on/off actuator with slight modification  75  and is used for transferring a flat pallet  76  to and from a flat pallet clamp  77  located on a machining center. 
         [0058]      FIG. 10A  When a pallet  1  or log pallet  2  is transferred to or from a machining center from a cart, it must pass over an opening that is necessary to accommodate the machining center enclosure doors. Another problem encountered during pallet transfer is vertical misalignment caused by the pallet weight shift from the machining center to the cart. These conditions were corrected by the following improvements. 
         [0059]      FIG. 10A  shows two extensions housed by the pallet rotary table bridge  5 . The first extension  80 , when extended, supports the pallet while crossing over the space provided for the machining center enclosure doors. The second extension  81 , when extended beyond the first extension  80 , engages the index station rail  41  to vertically align it with the bridge  5 . An air or hydraulic cylinder  83 ,  FIG. 10C  is used to extend the second extension  81  which in turn extends the first extension  80 . Retraction of the extensions is accomplished in reverse order. 
         [0060]      FIGS. 11A and 11B  shows a roller rail slide  84  that is guided by a roller rail guide  85  that is mounted to a tail stock  4 . The roller rail slide  84  is actuated by an air or hydraulic cylinder  86 . It is used to support the log while crossing over the space provided for the machining center enclosure doors and to engage and vertically align the support station located on the cart with the roller rail slide  84 . 
         [0061]    The tail stock is similar to that previously used and marketed, but was improved to combine with the roller rail extension See  FIG. 4  and provide a special actuator  31  used for engagement and support of a log pallet end and the ability to transfer air to the log that is stored in the log or pallet and is used for powered work piece clamping. The stored air is used for powered clamping when the pallet or log pallet is removed from its supply of air. The actuator  31  contains a piston  32  and houses it in a much shorter housing  31  that is more easily adjusted to align with the centerline of a log pallet  2 . The revised tail stock is combined with a roller retainer  36  that accepts compressed air that flows from the tail stock piston. The roller retainer  36  is fastened to a log pallet and is used to engage with the tail stock piston  32  for support and to transmit compressed air to the log pallet for storage. The compressed air transmitted thru the roller retainer  36  is also used to clean the engagement surface of the tail stock piston  32  and the roller retainer  36  and detect incomplete engagement by measuring abnormal pressure drop. 
         [0062]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.