Abstract:
A roller support apparatus includes a compression coil spring, lever, bias canceling member, roller holder, and support. The compression coil spring biases the distribution roller in a direction to come close to the oscillating roller. The lever transmits a biasing force of the compression coil spring to the distribution roller. The bias canceling member cancels bias of the compression coil spring. The roller holder rotatable supports the distribution roller and pivots in accordance with movement of the lever. The support is provided to the roller holder and engages with a shaft portion of the distribution roller. The support brings the outer surface of the distribution roller into contact with the outer surface of the oscillating roller in accordance with pivot motion of the roller holder.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a roller support apparatus and, more particularly, to a roller support apparatus provided to an inking device or dampening unit of a printing press to maintain the a contact pressure between two contacting rollers at a constant value. 
   In an inking device for an offset printing press, to uniform the thickness of ink to be supplied, a rubber roller and metal roller (an iron roller or a roller having a surface made of a hard metal such as copper) are rotated while their outer surfaces are in contact with each other, thus distributing the ink. According to this arrangement, the diameter of the rubber roller in contact with the metal roller changes due to wear or the like, leading to a change in contact pressure, i.e., nip pressure, between the rollers. When the nip pressure changes, the ink film thickness changes to largely adversely affect the printing quality. Therefore, conventionally, the inking device is provided with an adjustment unit which adjusts the nip pressure. 
   As shown in Japanese Patent Laid-Open No. 9-39211, a conventional roller support apparatus includes a support member which supports a distribution roller to be movable in directions to come close to and separate from an oscillating roller which is in contact with the distribution roller, a biasing member which biases the support member in a direction to urge the distribution roller against the oscillating roller, and a moving means for moving the distribution roller in the direction to separate from the oscillating roller against the biasing force of the biasing member. 
   In the conventional roller support apparatus described above, the biasing force of the biasing member is directly utilized without using a mechanism (amplification mechanism) that increases the biasing force. Hence, the biasing force itself of the biasing member must be large. In addition, in order to move the distribution roller in the direction to separate from the oscillating roller, the moving means is moved in the direction to accumulate the biasing force of the biasing member. The operation is thus cumbersome and time-consuming. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to improve the workability for attaching and detaching the roller. 
   In order to achieve the above object, according to the present invention, there is provided a roller support apparatus with which an outer surface of a first roller and an outer surface of a second roller come into contact with and separate from each other by radially moving the first roller, comprising a biasing member which biases the first roller in a direction to come close to the second roller, a lever which transmits a biasing force of the biasing member to the first roller, bias canceling means for canceling bias of the biasing member, a roller holder which rotatably supports the first roller and pivots in accordance with movement of the lever, and an axial support which is provided to the roller holder and which engages with a shaft portion of the first roller, the axial support serving to bring the outer surface of the first roller into contact with the outer surface of the second roller in accordance with pivot motion of the roller holder. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partially cutaway developed front view of an inking device for a printing press according to the first embodiment of the present invention; 
       FIG. 2  is an enlarged view of portion II of  FIG. 1 ; 
       FIG. 3A  is a view showing a state wherein a distribution roller is separated from an oscillating roller in the inking device shown in  FIG. 1 ; 
       FIG. 3B  is a view showing a state wherein the distribution roller is in contact with the oscillating roller in the inking device shown in  FIG. 1 ; 
       FIGS. 4A and 4B  are views for explaining the relation between the distribution roller and the bearing portion of a roller holder in the inking device shown in  FIG. 1 , in which  FIG. 4A  shows a state wherein the distribution is separate from the oscillating roller, and  FIG. 4B  shows a state wherein the distribution roller is in contact with the oscillating roller; and 
       FIGS. 5A and 5B  are front views of a roller holder according to the second embodiment of the present invention, in which  FIG. 5A  shows the relationship between the bearing portion of the roller holder and the bearing of a distribution roller when the distribution roller is separate from an oscillating roller, and  FIG. 5B  shows the relationship between the bearing portion of the roller holder and the bearing of the distribution roller when the distribution roller is in contact with the oscillating roller. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will be described in detail with reference to the accompanying drawings. 
     FIGS. 1 to 4B  show an inking device for a printing press according to the first embodiment of the present invention. Referring to  FIG. 1 , an inking device  1  for the printing press includes a pair of opposing frames  2 . An oscillating roller  4  as the second roller is axially supported by the pair of frames  2  through bearings  3  to be rotatable and movable in the axial direction. A gear  6  having a large face width is formed on one end shaft  5  of the oscillating roller  4 , and the inner teeth of an intermediate gear  7  mesh with the gear  6 . A driving gear  8  which transmits driving of a printing press motor meshes with the outer teeth of the intermediate gear  7 , and one end portion of a driving oscillating lever  9  engages with the distal end portion of one end shaft  5 . Therefore, when the printing press motor drives, the oscillating roller  4  rotates and moves reciprocally in the axial direction through the driving oscillating lever  9 . 
   A pair of inner frames  10  are arranged inside the pair of frames  2 , and are attached to the frames  2  to be parallel to them through studs (not shown). As shown in  FIGS. 3A and 3B , a bearing  12  integrally projects from one end face of each of a pair of substantially disk-like roller holders  11 . The bearing  12  has a U-shaped bearing portion  12   a  for supporting a bearing  18  (to be described later) of a distribution roller  16  (to be described later). An opening  12   b  of the bearing portion  12   a  has an open length slightly larger than the diameter of the bearing  18 . 
   As shown in  FIG. 2 , a first small shaft  13  integrally projects from the central portion of the other end face of each roller holder  11 . A second small shaft  14  having a diameter smaller than that of the first small shaft  13  integrally projects from the first small shaft  13  to form a step. A bearing  15  is mounted on the first small shaft  13 , and the roller holder  11  is rotatably supported by the corresponding inner frame  10  through the bearing  15 . At this time, the bearing  12  is located inside the inner frame  10 , and the second small shaft  14  projects outside the inner frame  10 . 
   The bearing  18  is mounted on the distal end portion of each end shaft  17  of the distribution roller  16  serving as the first roller which is in contact with the oscillating roller  4 . The distribution roller  16  is rotatably, axially supported by the bearing portions  12   a  of the pair of roller holders  11  through the bearings  18 . An ink roller  19  ( FIGS. 3A and 3B ) serving as the third roller in contact with the distribution roller  16  is rotatably, axially supported by the frames  2 . 
   The positional relationship between a shaft center G 1  of the roller holder  11  and a shaft center G 2  of the distribution roller  16  supported by the bearing  12  of the roller holder  11 , and the positional relationship between the bearing  12  of the roller holder  11  and the corresponding bearing  18  of the distribution roller  16 , when the distribution roller  16  is in contact with the oscillating roller  4 , will be described. 
   In the state shown in  FIG. 4A  wherein the distribution roller  16  is to be replaced, the opening  12   b  of the bearing  12  of the roller holder  11  is directed in the direction of an arrow A substantially perpendicular to a line  1  that connects the shaft centers of the oscillating roller  4  and ink roller  19 . In this state, when the bearing  18  of the distribution roller  16  is engaged in the bearing portion  12   a  of the bearing  12  of the roller holder  11  to bring the distribution roller  16  into contact with the ink roller  19 , the shaft center G 2  of the distribution roller  16  is positioned to deviate from the shaft center G 1  of the roller holder  11  by a distance d 1 . Simultaneously, a gap  20  with a distance δ is formed in the direction of an arrow B between the bearing  18  of the distribution roller  16  and the bearing portion  12   a  of the roller holder  11 . 
   In this state, when the roller holder  11  is pivoted counterclockwise, as shown in  FIG. 4B , a support (a cross-hatched portion)  12   c  as the lower-side one end portion of the bearing  12  of the roller holder  11  which supports the bearing  18  of the distribution roller  16  slightly moves the distribution roller  16  obliquely upward. At this time, the support  12   c  serves as a shaft support that supports the shaft of the distribution roller  16 . Thus, the distribution roller  16 , while being held in contact with the ink roller  19 , comes into contact with the oscillating roller  4 . 
   As shown in  FIG. 2 , one end of a lever  21  is axially mounted on the second small shaft  14  of the roller holder  11 , and one end of a rod  23  is pivotally mounted on the other end of the lever  21  through a pin  22 . Accordingly, when the rod  23  moves in the axial direction, the other end of the lever  21  also moves. As the lever  21  moves, the second small shaft  14  pivots, and the roller holder  11  also moves together with the second small shaft  14 . 
   A screw hole  24   a  parallel to the inner frame  10  is formed by threading in the inner surface of a stud  24  perpendicularly projecting from the inner frame  10 . A substantially cylindrical movable element  25  has a through hole  25   a  at its central portion, threaded portion  25   b  on its outer surface, and flange  25   c  at its one end. When the threaded portion  25   b  threadably engages with the screw hole  24   a , the movable element  25  is supported by the stud  24  to be movable in the directions of arrows A-B. When the flange  25   c  engages with the stud  24 , the movable element  25  is regulated from moving in the direction of the arrow B. The rod  23  is loosely inserted in the through hole  25   a  of the movable element  25  such that the distal end of the rod  23  projects from the flange  25   c . An engaging ring  26  is fitted on the projecting end portion of the rod  23 . 
   A locking ring  27  is fitted on end side of the rod  23 , and a compression coil spring  28  as a biasing member is elastically mounted between the ring  27  and the end face of the movable element  25 . A substantially bottomed cylindrical knob  30  is integrally placed on the flange  25   c  of the movable element  25  with a set screw  31 . A space  32  is formed between the knob  30  and flange  25   c , to accommodate the projecting end portion of the rod  23 , projecting from the flange  25   c , in a noncontact manner. 
   In this arrangement, when the knob  30  is pivoted to move the movable element  25  in the direction of the arrow B, the flange  25   c  abuts against the stud  24 . At this time, the compression coil spring  28  elastically mounted between the ring  27  and movable element  25  is compressed, and the spring force of the compression coil spring  28  moves the rod  23  in the direction of the arrow B. As the rod  23  moves, the lever  21  pivots counterclockwise as shown in  FIG. 3B  about the second small shaft  14  of the roller holder  11  as the pivot center. When the lever  21  pivots, the second small shaft  14  also pivots counterclockwise, and the roller holder  11  also pivots counterclockwise. 
   Then, the distribution roller  16  comes in contact with the oscillating roller  4 , as described above, such that their outer surfaces are in tight contact with each other ( FIG. 4B ). In this state, a gap t is formed, as shown in  FIG. 2 , between the ring  26  of the rod  23  and the flange  25   c  of the movable element  25 . The nip pressure between the distribution roller  16  and oscillating roller  4  generated by the spring force of the compression coil spring  28  is set to a predetermined value by adjusting the gap t. 
   In this manner, to generate the predetermined nip pressure between the distribution roller  16  and oscillating roller  4  by the spring force of the compression coil spring  28 , the spring force of the compression coil spring  28  is transmitted to the second small shaft  14  of the roller holder  11  through the lever  21 . In addition, a length d 2  ( FIG. 3A ) between the pin  22  of the lever  21  and the second small shaft  14  is set larger than the distance d 1  ( FIG. 4A ) between the shaft center G 1  of the bearing  12  of the roller holder  11  and the shaft center G 2  of the distribution roller  16 . 
   More specifically, the distance d 2  between the center of the pin  22  serving as the power point where the spring force of the compression coil spring  28  acts on the lever  21  and the shaft center G 1  of the first small shaft  13  serving as the pivot center of the roller holder  11  is set larger than the distance d 1  between the shaft center G 1  as the pivot center of the roller holder  11  and the shaft center G 2  of the distribution roller  16 . With this arrangement, the lever  21  exerts leverage, so that the predetermined nip pressure can be generated between the distribution roller  16  and oscillating roller  4  without increasing the spring force of the compression coil spring  28 . 
   The operation of attaching and detaching the distribution roller  16  in the roller support apparatus having the above arrangement will be described. 
   First, the attaching operation of bringing the distribution roller  16  into contact with the oscillating roller  4  will be described. As shown in  FIG. 3A , the opening  12   b  of the bearing  12  of the roller holder  11  is directed in the direction of the arrow A in advance. In this state, the bearing  18  of the distribution roller  16  is engaged into the bearing  12  of the roller holder  11  through the opening  12   b , to bring the distribution roller  16  into contact with the ink roller  19 . At this time, as described above, the shaft center G 2  of the distribution roller  16  is located to deviate from the shaft center G 1  of the roller holder  11  by the distance d 1 . Substantially, the knob  30  is pivoted to move the movable element  25  in the direction of the arrow B, so that the flange  25   c  abuts against the stud  24 . Thus, the compression coil spring  28  is compressed, and the rod  23  is moved in the direction of the arrow B by the spring force of the compression coil spring  28 . 
   At this time, since the movable element  25  is moved in the direction of the arrow B against the small spring force of the compression coil spring  28 , the pivoting force of the knob  30  can be decreased, thus improving the operability. As the movable element  25  moves in the direction of the arrow B, the lever  21  pivots counterclockwise as shown in  FIGS. 3B and 4B  about the second small shaft  14  of the roller holder  11  as the pivot center. Accordingly, the second small shaft  14  also pivots counterclockwise, and the roller holder  11  also pivots counterclockwise. Therefore, as described above, the distribution roller  16  comes into contact with the oscillating roller  4 , such that their outer surfaces are in tight contact with each other with the predetermined nip pressure. 
   At this time, the force that urges the oscillating roller  4  with pressure from the distribution roller  16  generates a counterforce to urge the distribution roller  16  downward in  FIG. 4B . As described above, the gap  20  is formed between the bearing  18  of the distribution roller  16  and the bearing  12  of the roller holder  11  in the direction of the ink roller  19  (direction of an arrow D). Thus, the counterforce toward the distribution roller  16  is transmitted in the direction of the arrow D as a partial force. 
   Hence, the distribution roller  16  moves in the direction of the arrow D as the bearing  18  is guided by the support  12   c  of the bearing  12  of the roller holder  11 , and the distance between the shaft center G 1  of the roller holder  11  and the shaft center G 2  of the distribution roller  16  changes from d 1  to d 1 ′ (d 1 &gt;d 1 ′). In this manner, the distribution roller  16  is urged in the direction of the arrow D so that its outer surface comes into tight contact with the outer surface of the ink roller  19 , and the distribution roller  16  is brought into contact with the ink roller  19  with the predetermined nip pressure. 
   At this time, as shown in  FIG. 4B , the distribution roller  16  is supported at a contact point H 1  with respect to the ink roller  19 , contact point H 2  between the bearing  18  and the support  12   c  of the bearing  12 , and contact point H 3  with respect to the oscillating roller  4 . When the distribution roller  16  is brought into contact with the oscillating roller  4  with the predetermined nip pressure, as described above, the distribution roller  16  is also brought into contact with the ink roller  19  with the predetermined nip pressure. Thus, the nip pressure adjusting operation can be performed easily within a short period of time. 
   The detaching operation of separating the distribution roller  16  from the oscillating roller  4  and the operation of changing the distribution roller  16  will be described. 
   When the knob  30  is pivoted, the movable element  25  moves in the direction of the arrow A from the state shown in  FIG. 2 , and the compression coil spring  28  expands to decrease its spring force. Accordingly, the biasing force to bias the rod  23  in the direction of the arrow B decreases. Thus, the lever  21  can pivot clockwise in  FIG. 3B  about the second small shaft  14  as the pivot center. In this case, the stud  24 , the movable element  25  supported by the stud  24  to be movable forward/backward, and the knob  30  which moves the movable element  25  form a bias canceling means  35  which cancels bias of the compression coil spring  28  to the lever  21 . 
   When the knob  30  is pivoted sequentially, the end face of the flange  25   c  of the movable element  25  abuts against the ring  26  of the rod  23 , to move the rod  23  in the direction of the arrow A. Therefore, as shown in  FIG. 3A , the lever  21  pivots clockwise about the second small shaft  14  as the pivot center. 
   Along with this, the second small shaft  14  also pivots clockwise, and the roller holder  11  also pivots clockwise, as shown in  FIG. 4A . Therefore, the distribution roller  16  moves slightly obliquely downward due its own weight, and separates from the oscillating roller  4  to disengage from it. 
   In this manner, when the distribution roller  16  is to be separated from the oscillating roller  4  to disengage from it, the movable element  25  is moved in the direction of the arrow A by utilizing the spring force of the compression coil spring  28 . Thus, the pivoting force of the knob  30  can be decreased, thus improving the operability. 
   In this state, when replacing the distribution roller  16 , as shown in  FIG. 4A , the bearing  18  of the distribution roller  16  is removed through the opening  12   b  of the bearing  12  of the roller holder  11  which is directed in the direction of the arrow A. Hence, the old distribution roller  16  can be removed from the roller holder  11 . At this time, as shown in  FIG. 4A , the distribution roller  16  is removed or attached as it is supported at two points, i.e., a contact point I 1  with respect to the ink roller  19  and a contact point I 2  between the bearing  18  and the support  12   c  of the bearing  12 . 
   Subsequently, a bearing  18  of a new distribution roller  16  is engaged into the bearing  12  through the opening  12   b . The old distribution roller  16  is changed for the new distribution roller  16  by the attaching operation of the distribution roller  16  described above. In this manner, as the opening  12   b  is formed in the bearing  12  of the roller holder  11 , when the distribution roller  16  is to be changed, not only no tools are needed, but also the operation time can be shortened. 
   The distribution roller  16  is disposed inside the inner frames  10  arranged inside the frames  2 . The levers  21 , rods  23 , compression coil springs  28 , knobs  30 , and the like are disposed outside the inner frames  10  (between the frames  2  and inner frames  10 ), respectively. Thus, the ink scattering from the distribution roller  16  can be regulated from scattering outside the inner frames  10 , and the ink can be prevented from attaching to the levers  21 , rods  23 , compression coil springs  28 , knobs  30 , and the like. As a result, operation errors of the levers  21 , rods  23 , compression coil springs  28 , knobs  30 , and the like can be prevented, and the attaching/detaching operation of the distribution roller  16  can be performed reliably. 
     FIGS. 5A and 5B  show the second embodiment of the present invention. 
   According to the characteristic feature of the second embodiment, a bearing portion  12   a  of a bearing  12  of a roller holder  11  is formed of a cam, so that the distance between the bearing portion  12   a  and a shaft center G 1  of the roller holder  11  may gradually decrease from a lower-side one end (point E) toward a central side (point F). In other words, a distance R 2  between G 1  and the point F is set smaller than a distance R 1  between G 1  and the point E. 
   With this arrangement, when a bearing  18  of a distribution roller  16  is supported at the point E of the bearing portion  12   a , as shown in  FIG. 5A , the distribution roller  16  is separate from an oscillating roller  4 . In this state, when the roller holder  11  is pivoted counterclockwise as shown in  FIG. 5B , the bearing  18  is supported at the point F of the bearing portion  12   a . As the distance R 2  between G 1  and the point F is set smaller than the distance R 1  between G 1  and the point E, the bearing  18  moves upward. Thus, the distribution roller  16  comes into contact with the oscillating roller  4 . 
   In the respective embodiments described above, the bearing portion  12   a  of the bearing  12  of the roller holder  11  is formed to have a U-shape. Alternatively, only the support  12   c  which supports the bearing  18  of the distribution roller  16  may be formed. Although the above embodiments exemplify a case wherein the roller support apparatus is applied to a printing press, the roller support apparatus can also be applied to a coating device. Although the above embodiments exemplify a case wherein the roller support apparatus is applied to an inking device, the roller support apparatus can also be applied to a dampening unit. 
   The distribution roller  16  is brought into contact with the oscillating roller  4  by pivoting the roller holder  11  connected to the lever  21 . Alternatively, one end of the lever  21  may be connected to a support member that supports the bearing  18  of the distribution roller  16 . The distribution roller  16  may be brought into contact with the oscillating roller  4  by moving the support member. 
   As has been described above, according to the present invention, when the movable roller is to be brought into contact with or is to be separated from the stationary roller, the operability improves. When replacing the movable roller, not only no tools are needed, but also the operation time can be shortened. The operation of adjusting the nip pressure can be performed easily within a short period of time. As the ink can be prevented from scattering from the ink roller, the operation of attaching and detaching the movable roller can be performed reliably.