Abstract:
A clamping device is described for clamping a log such as a log of wound material. The inventive clamping device addresses the need for more efficient or flexible clamping systems for logs of wound material that may vary in their diameter, wherein the clamping allows the logs to be cut by a cutting machine to sections of desired length.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to a log clamping device, and more particularly to a log clamping device associated with a cutting machine. The cutting machine is applied to cut “logs” comprising web material wound on tubular winding cores. The log clamping device clamps the log in the cutting process. 
     2. Description of the Related Art 
     In typical applications, a log such as a wound tissue log is cut into rolls of smaller size by a rotating circular knife in a cutting machine. The log is held and supported by a clamping device in the cutting process. 
     A typical clamping device is configured for securing logs of constant size. Related structures of prior clamping devices may need to be replaced when the size of the logs is changed in order to properly clamp, making it inconvenient or inefficient to change log diameters. Therefore, there is a need for more efficient or flexible clamping systems for cutting logs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front-side view of a clamping device of an exemplary embodiment of the present disclosure, wherein logs are shown in the clamping device. 
         FIG. 2  is a cross-sectional view of the clamping device of  FIG. 1 , taken along line II-II thereof. 
         FIG. 3  is another front-side view of the clamping device of  FIG. 1 , wherein the diameter of the logs is larger than that in  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the clamping device of  FIG. 3 , taken along line IV-IV thereof. 
         FIG. 5  is a cross-sectional view of a clamping device of another exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring to  FIG. 1  and  FIG. 2 , a clamping device  1  in accordance with an exemplary embodiment of the present disclosure is shown for holding and supporting a circumferential surface  101  of a log  100  in a cutting process, in which the log  100  is cut by a cutting machine into rolls of smaller sizes. The log  100  can be a tissue log or other kinds of web material wound on a tubular winding core  102 . 
     The clamping device shown in  FIG. 2  has two clamping units  2  and  3  for holding two lanes of logs  100 . The two clamping units  2  and  3  have similar structures. In alternative embodiments, the clamping device may have one clamping unit for holding a single log  100 , or may be provided with more than two clamping units for holding more than two logs  100 . 
     The clamping device having one clamping unit is set forth as an example for a detailed description as follows. The clamping device comprises a frame  10 , a supporting arm  11  fixed on the frame  10 , a base plate  12 , a pair of cradles  131 ,  132  disposed on the base plate  12  and a pair of clamps  141 ,  142  respectively connected to the cradles  131 ,  132 . The clamp  141  is fixed on the cradle  131 . The clamp  142  is pivotably connected to the cradle  132 , and is capable of rotating and shifting between a clamping position and an open position. The log  100  is supported on the supporting arm  11 . As shown in  FIG. 2 , when the clamp  142  is in the clamping position, the supporting arm  11  locates at a bottom of the circumferential surface  101  of the log  100  and the clamps  141 ,  142  are symmetrically located at opposite sides of the circumferential surface  101  of the log  100 . The supporting arm  11  and the clamps  141 ,  142  cooperate to secure the log  100  for facilitating the cutting process of the log  100 . When the clamp  142  is in the open position (dotted lines shown in  FIG. 2 ), the log  100  will be unrestrained among the supporting arm  11  and the clamps  141 ,  142 . The supporting arm  11 , in typical embodiments, does not move vertically when the base plate  12  moves vertically, but remains at a substantially constant elevation to support logs. In one embodiment, when the clamp  142  is in the open position, the minor distance d between the clamps  141 ,  142  (i.e., the distance d between free ends  143 ,  144  of the clamps  141 ,  142  as shown in  FIG. 2 ) is larger than the diameter of the log  100  for allowing the log  100  to move between the clamps  141 ,  142  more easily to allow new regions of the log  100  to be cut. 
     Multiple pairs of cradles and clamps can be arranged along the axial direction of the log  100  as desired. Two clamps  142   a ,  142   b  are shown in  FIG. 1  and are distributed along the axial direction of the log  100 . Accordingly, the supporting arm  11  can extend to a predetermined length along the axial direction of the log  100  for holding the log  100 . 
     For conforming with the circumferential surface  101  of the log  100 , the clamps  141 ,  142  may have a curved shape in some embodiments. The clamps  141 ,  142  can be configured to include sub-clamps for increasing a contacting surface between the clamps  141 ,  142  and the log  100 . The clamps  142   a ,  142   b  shown in  FIG. 1  each have two sub-clamps  145  and in some embodiments may present a U shape or other suitable shapes. The distance between the sub-clamps  145  of the clamp  142   a  is smaller than that of the clamp  142   b . Alternatively, the clamp  141  can have a similar structure to the clamp  142 , but need not similar but may have any suitable shape known in the art. In addition, the cradles  131 ,  132  can each include sub-cradles for connecting a corresponding sub-clamp  145 . 
     The clamp  142  is connected to an actuator  15 . The actuator  15  drives the rotation of the clamp  142  relative to the cradle  132  between the clamping position and the open position. 
     The actuator  15  is positioned beneath the base plate  12 , and penetrates through the base plate  12  to connect the clamp  142 . The actuator  15  can be a pneumatic cylinder, a hydraulic cylinder or other equivalent structures. A motor  150  is used to move a pusher (not shown) that moves the log  100  into position to be clamped and moves the log  100  away from the clamps  141 ,  142  after cutting is completed. 
     The supporting arm  11  extends upwardly from the frame  10  and comprises two branches  111 ,  112 . The section profile of the supporting arm  11  is substantially a Y shape or a V shape, though other shapes may be contemplated such as a more curved, less angular shape capable of holding the log  100 . The branches  111 ,  112  contact and help support the bottom of the circumferential surface  101  of the log  100 . 
     In some embodiments such as the embodiment shown in  FIG. 2  and  FIG. 4 , the clamping device may further comprise a cam mechanism corresponding to each cradle  131 ( 132 ). The cam mechanism comprises a profile  16  fixed on the frame  10 , and a follower  17  disposed on the cradle  131 ( 132 ) to match with the profile  16 . The profiles  16  for the two cam mechanisms corresponding to the cradles  131 ,  132  may be symmetrical relative to the center of the two clamping units  2 ,  3 , as shown in  FIG. 2  and  FIG. 4 , or, in other words, can be mirror images of one another reflected about a vertical plane parallel to the axis of the logs and normal to the plane of  FIG. 2 , passing through a central region of the clamping device. The profile  16  shown in the embodiment has a bottom end near the base plate  12  and an opposite top end far from the base plate  12 . The profile  16  as depicted has a surface  161  matching with the follower  17 , and gradually slant from the bottom end to the top end thereof. Of course, a wide variety of other profile shapes can be used, including substantially linear profiles and profiles with more complex curves or both linear and curved sections. The distance between the two profiles  16  increases gradually from the bottom ends to the top ends thereof. When the follower  17  moves along the surface  161  of the corresponding profile  16 , the distance between the two cradles  131 ,  132  is changed gradually. More specifically, when the follower  17  moves upwardly along the surface  161  from the bottom end to the top end of the profile  16 , the distance between the cradles  131 ,  132  is increased gradually. When the follower  17  moves downwardly along the surface  161  from the top end to the bottom end of the profile  16 , the distance between the cradles  131 ,  132  is decreased gradually. 
     The base plate  12  is moveably connected to at least one post  18 .  FIG. 2  shows two posts  18  connecting the base plate  12 . When the base plate  12  moves along the posts  18  downward or upward, as a result, the distance between the base plate  12  and the supporting arm  11  and the distance between the clamps  141 ,  142  and the supporting arm  11  is changed, thereby allowing the clamping device to be suitable for clamping logs  100  with different diameters. 
     In the present embodiment, the posts  18  are depicted as screws, and the base plate  12  is threadedly engaged with the posts  18 , though other mechanisms may be used for moving the base plate  12 . The posts  18  as shown can be rotated by a motor  19 , and the base plate  12  is moved along the posts  18 . The motor  19  can be fixed on the frame  10 . 
     The cradles  131 ,  132  are moveably connected to the base plate  12 . For example, the cradles  131 ,  132  can be slidably disposed on the base plate  12 . In the present embodiment, rails  121  and tracks  122  are formed between the cradles  131 ,  132  and the base plate  12  to accomplish the slidable movement between the cradles  131 ,  132  and the base plate  12 . 
     The follower  17  is rotatably arranged on the cradle  131 ,  132  and engages with the surface  161  of the profile  16  fixed on the frame  10 . Through the motion of the follower  17 , the cradle  131 ,  132  can slide on the base plate  12 , and the distance between the clamps  141 ,  142  (as well as that between the cradles  131 ,  132 ) can be changed. The follower  17  can also be controlled to stop at a desired position to maintain a fixed distance between the cradles  131 ,  132 . In alternate embodiments, the follower  17  can be driven directly by a motor (not shown) or other power supply or other device such as an airbag or pneumatic cylinder (not shown). 
     With the upward or downward movement of the base plate  12  relative to the supporting arm  11 , the distance between the clamps  141 ,  142  and the supporting arm  11  (i.e., the vertical position of the clamps  141 ,  142 , the cradles  131 ,  132 , and the base plate  12 ) can be adjusted. At the same time, with the rotation of the follower  17 , the cradles  131 ,  132  can slide on the base plate  12  and the distance between the cradles  131 ,  132  (i.e., the horizontal position of the cradles  131 ,  132  and the clamps  141 ,  142 ) can be adjusted. As a result, the supporting arm  11  and the clamps  141 ,  142  can be adjusted to hold and support logs  100  with different diameter, and there is no need to replace relative parts of the clamping device, which is more convenient and rapid in production. 
     The operation principles of the clamping device provide in the present disclosure will be more detailed described as follows with  FIG. 3  and  FIG. 4 . The logs  200  shown in  FIG. 3  and  FIG. 4  have a larger diameter than the logs  100  shown in  FIG. 1  and  FIG. 2 . 
     If the clamping device as shown in  FIG. 1  and  FIG. 2  needs to hold and support the logs  200  as shown in  FIG. 3  and  FIG. 4 , the posts  18  rotate, and the base plate  12  moves upwardly to increase the distance between the supporting arm  11  and the clamps  141 ,  142 ; at the same time, the follower  17  rotates and moves upwardly along the surface  161  of the profile  16 , and the cradles  131 ,  132  slide on the base plate  12 , whereby the distance between the cradles  132 ,  132  and between the clamps  141 ,  142  is increased. After the rotation of the clamp  142 , where the clamp  142  is in the open position, the log  200  can be inserted among the supporting arm  11  and the clamps  141 ,  142 . The log  200  is then secured by the supporting arm  11  and the clamps  141 ,  142  after a reversed rotation of the clamp  142 , where the clamp  142  is in the clamping position. 
     In the above embodiment, the cradles  131 ,  132  are moveably arranged on the frame  10  via the cam mechanisms to change the horizontal positions thereof. It is noted that the cradles  131 ,  132  can be moveably arranged on the frame  10  in different manners, including configurations without the need for the profile  16  and the follower  17  of  FIG. 2 . Referring to the alternative embodiment shown in  FIG. 5 , each cradle  131 ,  132  is connected to a cradle actuator  20 . The cradle actuator  20  may be an electric, pneumatic, or hydraulic actuator, and may comprise an electric motor. The horizontal positions of the cradles  131 ,  132  on the base plate  12  can be changed by the driving of the cradle actuator  20 . In other words, the distance between the cradles  131 ,  132  can be adjusted by the driving of the cradle actuator  20 . In such way, the horizontal positions of the cradles  131 ,  132  and the vertical positions of the cradles  131 ,  132  can be controlled independently. 
     In alternative embodiments, the cradle actuator  20  can be a rack and pinion system formed between the cradles  131 ,  132  and the base plate  12 . 
     Further, the moveable connection between the base plate  12  and the post  18  is not limited to screws. Other systems such as linear actuators, or rack and pinion can also be formed between the base plate  12  and the post  18  to accomplish the vertical position adjustment of the base plate  12 . 
     It is to be further understood that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.