Patent Publication Number: US-9427887-B2

Title: Concrete product molding machine vibration drive apparatus

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of and is based on provisional patent application Ser. No. 61/850,040 filed Feb. 5, 2013. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND 
     1. Field 
     This application relates generally to mold vibrators for concrete product molding machines. 
     2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98 
     Molds for concrete product molding machines are vibrated to provide better filling of the mold. Mold vibration also assists the formation of denser concrete products by allowing the concrete to settle to a more structurally sound state. Some concrete product molding machines include a frame, and a mold assembly carried by the frame. A pallet and pallet receiver of the concrete product molding machine are raised to pick-up the mold assembly from a rest position and raise it to an elevated vibration position approximately ⅝ inch above the rest position. Two unbalanced vibrator shafts are carried by the mold assembly and are supported for rotation about respective parallel vibrator shaft axes, each vibrator shaft axis being displaced from a center of mass of that vibrator shaft so that each vibrator shaft produces off-axis force when rotated about its vibrator shaft axis. The vibrator shafts are driven in rotation by respective vibration drives comprising electric drive motors, belts, and pulleys. A concrete product molding machine of this type is disclosed, at least in part, in U.S. Pat. No. 4,978,488 issued Dec. 18, 1990 to Wallace, which is incorporated herein in its entirety, by reference. 
     SUMMARY 
     A vibration drive assembly is provided for a concrete product molding machine that comprises a frame, a mold assembly, a pallet and pallet receiver actuable to move the mold assembly between a rest position and an elevated vibration position, two unbalanced vibrator shafts carried by the mold assembly and supported for rotation about respective parallel vibrator shaft axes, each vibrator shaft axis having an eccentric center of mass such that each vibrator shaft produces off-axis force when rotated about its vibrator shaft axis. The vibration drive assembly comprises two rotary servo motors and an electronic motor controller electrically coupled to the servo motors and configured to regulate the motors and operate them in synchronism with one another at a predetermined rotational speed. Two articulated drive trains are connectable between the servo motors and the vibrator shafts and configured to mechanically transmit rotational motion from the servo motors to the vibrator shafts when the mold assembly is in its vibration position with the vibrator shaft axes coaxially aligned with rotational servo motor axes, and to remain connected between the servo motors and vibrator shafts when the mold assembly is in its rest position with the vibrator shaft axes axially mis-aligned with respect to the servo motor axes. 
     Also, a vibration drive assembly is provided for a concrete product molding machine that comprises a frame, a mold assembly, a mold assembly supported on the frame for motion between a rest position and an elevated vibration position, two unbalanced vibrator shafts carried by the mold assembly and supported for rotation about respective parallel vibrator shaft axes, each vibrator shaft axis having an eccentric center of mass such that each vibrator shaft produces off-axis force when rotated about its vibrator shaft axis. The vibration drive assembly comprises two rotary servo motors and an electronic motor controller electrically coupled to the servo motors and configured to regulate the motors and operate them in synchronism with one another at a predetermined rotational speed. Two articulated drive trains are connectable between the servo motors and the vibrator shafts and configured to mechanically transmit rotational motion from the servo motors to the vibrator shafts. The servo motors and attached drive trains are pivotably supportable on a concrete product molding machine frame for motion between respective stowed and deployed positions where, in their stowed positions, the servo motors and attached drive trains are disposed out of a removal and replacement path of a mold assembly of the concrete product molding machine, and where, in their deployed positions, the servo motors and attached drive trains are disposed within the removal and replacement path with the drive trains positioned adjacent vibrator shafts of the concrete product molding machine. 
     Also, a method is provided for retrofitting a vibration drive assembly on a concrete product molding machine that comprises a frame, a mold assembly, a pallet and pallet receiver actuable to move the mold assembly between a rest position and an elevated vibration position, two unbalanced vibrator shafts carried by the mold assembly and supported for rotation about respective parallel vibrator shaft axes, each vibrator shaft axis having an eccentric center of mass such that each vibrator shaft produces off-axis force when rotated about its vibrator shaft axis. The method includes supporting two rotary servo motors of the vibration drive assembly in respective positions with respective servo motor axes co-axially aligned with the vibrator shaft axes when the mold assembly of the molding machine is in its elevated vibration position, and connecting two articulated drive trains of the vibration drive assembly between the servo motors of the vibration drive assembly and the vibrator shafts of the molding machine, in respective positions to mechanically transmit rotational motion from the servo motors to the vibrator shafts when the mold assembly is in its vibration position with the vibrator shaft axes coaxially aligned with rotational servo motor axes, and to remain connected between the servo motors and vibrator shafts when the mold assembly is in its rest position with the vibrator shaft axes axially mis-aligned with respect to the servo motor axes. 
    
    
     
       DRAWING DESCRIPTIONS 
       These and other features and advantages will become apparent to those skilled in the art in connection with the following detailed description and drawings of one or more embodiments of the invention, in which: 
         FIG. 1  is a partial, fragmentary, orthogonal view of a prior art concrete product molding machine having a removable mold assembly comprising a concrete product mold and two vibrator shafts driven by prior art vibration drives comprising electric motors, pulleys, and drive belts; 
         FIG. 2  is an orthogonal view of the removable mold assembly of the prior art molding machine of  FIG. 1 ; 
         FIG. 3  is a partial orthogonal view of the prior art concrete product molding machine of  FIG. 1  with the vibrator shafts connected to vibration drives constructed according to the present disclosure; 
         FIG. 4  is a partial orthogonal view of the prior art concrete product molding machine of  FIG. 1  with motors and drive trains of the vibration drives disconnected from vibrator shafts and rotated out of a removal path of the removable mold assembly of the prior art concrete products molding machine; 
         FIG. 5  is an orthogonal view of the concrete product molding machine and vibration drives of  FIG. 3  including a partial exploded view of a drive train of one of the two vibration drives; 
         FIG. 6  is a side view of the concrete product molding machine and one of the vibration drives of  FIG. 3 ; 
         FIG. 7  is an end view of the concrete product molding machine and vibration drives of  FIG. 3 ; 
         FIG. 8  is a magnified partially cut-away side view of one of the vibrator shafts of the removable mold assembly of the concrete product molding machine of  FIG. 3 , connected to a drive train of one of the vibration drives of  FIG. 3 , with the removable mold assembly in its vibration position and vibrator shaft, drive train, and motor axes coaxially aligned; and 
         FIG. 9  is a magnified partially cut-away side view of the vibrator shaft of  FIG. 8  connected to the drive train of  FIG. 8 , with the removable mold assembly of the concrete product molding machine in its rest position and with vibrator shaft, drive train, and motor axes axially mis-aligned. 
     
    
    
     DETAILED DESCRIPTION 
     A vibration drive assembly for retrofit on a concrete product molding machine is generally shown at  10  in  FIGS. 3-7 . A concrete product molding machine, of the type for which the vibration drive assembly  10  is designed for retrofit, is shown at  11  in  FIGS. 1 and 3-7 . As best shown in  FIGS. 3-5 , a molding machine of this type comprises a frame  12 , a removable mold assembly  14 , a pallet (not shown), and a pallet receiver  18 . The pallet receiver  18  is actuable to move the mold assembly  14  between a rest position and an elevated vibration position that may be spaced approximately ⅝ inch above the rest position. It is in the elevated vibration position where the mold assembly  14  is subjected to vibration. 
     As best shown in  FIGS. 2, 8, and 9 , two unbalanced vibrator shafts  20  are carried by the mold assembly  14  and are supported for rotation about respective parallel vibrator shaft rotational axes  21 . Each vibrator shaft  20  has an eccentric center of mass (i.e., a center of mass displaced from a rotational axis  21  of that vibrator shaft  20 ) such that each vibrator shaft  20  produces off-axis force when rotated about its vibrator shaft axis  21 . 
     As shown in  FIGS. 3-7 , the drive assembly  10  may include two closed-loop rotary servo motors  22  such as, for example, synchronous servo motors available from Rexroth under the product designation IndraDyn S MSK. As best shown in  FIGS. 3-5 , two articulated drive trains  24  may be connected between the servo motors  22  and the vibrator shafts  20  and configured to mechanically transmit rotational motion from the servo motors  22  to the vibrator shafts  20 , i.e., to rotate the vibrator shafts  20  about their respective vibrator shaft axes  21  when the mold assembly  14  is in its raised vibration position, as best shown in  FIG. 8 , with the vibrator shaft axes  21  coaxially aligned with rotational servo motor axes  25 . The drive trains  24  may be configured to remain connected between the servo motors  22  and vibrator shafts  20  when the mold assembly  14  is in its rest position, as best shown in  FIG. 9 , with the vibrator shaft axes  21  displaced vertically and axially mis-aligned (i.e., not coaxially aligned) with respect to the servo motor axes  25 . 
     As shown in  FIGS. 3-5 , each drive train  24  may include a drive shaft  26  and a first flexible coupling  28  connected between the servo motor  24  and the first end of the drive shaft  26 . The first flexible coupling  28  may be configured to transmit rotation from the servo motor  24  to the drive shaft  26  and to permit relative angular motion between the drive shaft  26  and the servo motor  24  when the mold assembly  14  is moved between its rest position and elevated vibration position. A second flexible coupling  30  may be carried by each drive shaft  26 . The second flexible coupling  30  may be connected between a second end of each drive shaft  26  and one of the vibrator shafts  20  and configured to transmit rotation from each drive shaft  26  to a respective corresponding vibrator shaft  20  and to permit relative angular motion between the drive shafts  26  and the vibrator shafts  20 . The flexible couplings  28 ,  30  may comprise any suitable coupling, for example, joint disk couplings available from SGF. 
     As best shown in  FIG. 9  each drive train  24  may include a drive train support bearing  32  carried by a drive train support bracket  33  that is carried by the frame  12 . The support bearing  32  may support the drive train  24  for rotation about a drive shaft axis  27 , thereby extending servo motor life by reducing loads applied to a front end bearing of the servo motor  24 . The drive train support bearing  32  may be of any suitable type to include, for example, a double row ball bearing available from SKF. 
     As shown in  FIG. 9 , each drive train  24  may include an axial float coupling  34  connected in the drive train  24  between the servo motor  24  and the drive shaft  26 . The axial float coupling  34  may extend servo motor life by reducing axial loads applied to the servo motor  24 . The axial float coupling  34  may be of any suitable type to include, for example, an EKH/300 coupling available from R+W® Coupling Technology. 
     As shown in  FIG. 9 , the drive shaft  26  of each drive train  24  may have a length sufficient to limit a first acute angle α measured between the drive shaft axis  27  and servo motor axis  25  and a second acute angle β measured between the drive shaft axis  27  and the vibrator shaft axis  21  (when the drive train  24  is connected to a vibrator shaft  20  of the concrete product molding machine  11  and the mold assembly  14  of the concrete product molding machine  11  is in its rest position), to less than respective maximum angles allowable by the first and second flexible couplings  28 ,  30  for a given distance between the rest position and elevated vibration position of the mold assembly  14  of a concrete product molding machine  11  to which the drive trains  24  are to be connected, where the distance between rest and elevated positions is measured in a direction generally normal to the orientation of the drive shaft  26  when the drive train  24  is connected to a vibrator shaft  20  of the concrete product molding machine  11 . 
     As shown in  FIGS. 6 and 7 , an electronic motor controller  35  may be electrically coupled to the servo motors  22 . The motor controller  35  may be configured to regulate the motors  22  and operate them in synchronism with one another at a predetermined rotational speed as disclosed, for example, in U.S. Pat. No. 5,355,732 issued Oct. 18, 1994 to Anderl et al. and incorporated herein in its entirety, by reference. The motor controller  35  may be configured to change the vibrating frequencies of the vibrator shafts  20  by changing their rotational speed and/or the motor controller  35  may be configured to change vibration amplitude by changing the vibrating frequencies of the vibrator shafts  20 . 
     As shown in  FIGS. 3 and 4 , the servo motors  22  and attached drive trains  24  may be pivotably supported on the frame  12  for motion between respective stowed and deployed positions. In their stowed positions, shown in  FIG. 4 , the servo motors  22  and attached drive trains  24  may be disposed out of a removal and replacement path  36  of a mold assembly  14  of the concrete product molding machine  11  to facilitate the clearing of the removal and replacement path  36  for the mold assembly  14 . In their deployed positions, shown in  FIG. 3 , the servo motors  22  and attached drive trains  24  are disposed within the removal and replacement path  36  with the drive trains  24  positioned adjacent the vibrator shafts  20  of the concrete product molding machine  11  for attachment thereto. 
     To enable the pivotable mounting of the motors  22  and drive trains  24 , the drive assembly  10  may include two pivot mount assemblies  38  best shown in  FIG. 5 . Each such assembly  38  may comprise a vertical pivot shaft  40  supported for rotational motion within a pivot mount sleeve  42  fixed to the concrete product molding machine frame  12 , a hinge plate  44  fixed to the pivot shaft  40 , and a motor mount  46  fixed to the hinge plate  44 . Each motor mount  46  may removably carry one of the servo motors  22 . The servo motor  24  may be removably attached to the motor mount  46  by four fasteners  48 . 
     The vibration drive assembly  10  may be retrofit on a concrete product molding machine  11  by removing belts and pulleys from the vibrator shafts  20  of the molding machine  11  and pivotably supporting the two rotary servo motors  22  of the vibration drive assembly  10  in respective positions on the frame  12  of the molding machine  11 , where respective servo motor axes are co-axially alignable with the vibrator shaft axes of the mold assembly of the molding machine when the mold assembly is in its elevated vibration position. The two articulated drive trains  24  of the vibration drive assembly  10  are assembled and connected between the servo motors  22  of the vibration drive assembly  10  and the vibrator shafts  20  of the molding machine  11 . The servo motors  22  are connected to the motor controller  35  and the motor controller  35  is programmed to operate the servo motors  22  in synchronism with one another and rotate the vibrator shafts  20  of the molding machine at a predetermined rotational speed when the mold assembly  14  of the molding machine  11  is in its vibration position, and may be further programmed to prevent the servo motors  22  from rotating the vibrator shafts  20  of the molding machine  11  when the mold assembly  14  of the molding machine  11  is in its rest position. 
     A vibration drive assembly  10 , as described above, provides force amplitude control of vibrator shafts  20  of a concrete product molding machine  11  and replaces a belt drive with a direct drive via servo motors  22  and drive trains  24  that can be easily disconnected and rotated to clear a path for mold assembly  14  removal and replacement. The articulation of the drive trains  24  allows them to remain connected when the mold assembly  14  is lowered to its rest position between vibration operations. 
     This description, rather than describing limitations of an invention, only illustrates an embodiment of the invention recited in the claims. The language of this description is therefore exclusively descriptive and is non-limiting. Obviously, it&#39;s possible to modify this invention from what the description teaches. Within the scope of the claims, one may practice the invention other than as described above.