Abstract:
A rubbing machine and its tool pan are disclosed. The tool pan ( 122 ) comprises a number of homocentric annular structures ( 125 ) which have a lot of rubbing zones ( 121 ). Provided between the contiguous rubbing zones is at least a ramp ( 127 ), which is extending along the normal of the tool pan, and the height of which is increased gradually towards the fringe of the tool pan. In the rubbing machine ( 100 ) the tool pan is used. The rubbing machine is applicable in paper making industry, and can effectively separate and fibrillate the fiber of herbage by mechanical force between a pair of tool pans, thereby needing not to use chemicals, and according with the modern conception of environmental protection.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a rubbing machine, and more particularly, to a rubbing machine capable of separating and fibrillating fibers of herbage and a tool pan thereof. 
         [0003]    2. Descriptions of the Related Art 
         [0004]    Ecological materials can be easily obtained from the nature without the concern of shortage in supply. Use of the ecological materials can reduce the dependence on resources to reduce the resource consumption and can eliminate the need of developing new kinds of resources, so great importance has been attached to use of the ecological materials. Correspondingly, extracting ecological materials from plants and transforming the ecological materials into new kinds of industrial products has become an important trend. Among such ecological materials, ecological fibers are known as a very important kind. 
         [0005]    Natural plant fibers have been used in industries related to paper making, textiles, building, construction and so on. Currently, fibers used in China are mainly wood fibers. However, because of the exceeding deforestation of forests and the increased demand of reducing the exhaust of greenhouse gases, replacing the wood fibers with plant fibers (e.g., bamboo fibers, rice straw fibers, wheat straw fibers and so on) that are abundant in China will create more economical benefits. 
         [0006]    To satisfy the demands for ecological fibers, a fiber separating technology that has a high efficiency and is environmentally friendly must be developed. Conventional fiber separating methods include chemical separating methods and steam explosion separating methods. According to the chemical separating methods, chemicals such as alkaline solutions are used to separate the fibers. However, the separating process produces a great amount of pollutants which are unfavorable for environmental protection, and the fibers are largely damaged by the chemicals, so the fiber yield is as low as about 40˜50%. Furthermore, if the fibers separated by using the chemicals are to be used in food containers, the fibers must be cleaned to remove the chemicals completely, and this increases the processing cost. For the steam explosion methods, repeated cycles of rapidly decreasing and increasing the steam pressure are carried out to separate the fibers through explosion, and this is both time and energy consuming and delivers poor uniformity of fibers. 
       SUMMARY OF THE INVENTION 
       [0007]    In view of this, the present invention provides a rubbing machine that can separate plant fibers without using chemicals. 
         [0008]    The present invention further provides a tool pan that can improve the separating rate of plant fibers. 
         [0009]    A rubbing machine disclosed in the present invention comprises a housing, a tool pan assembly and a driving element. The housing has a feeding inlet and a discharging outlet. The tool pan assembly is disposed inside the housing and comprises two tool pans that are spaced apart by an interval to form a rubbing space that interconnects between the feeding inlet and the discharging outlet. Each of the tool pans comprises a plurality of homocentric annular structures. Each of the homocentric annular structures has a plurality of rubbing zones, and at least one ramp is disposed between adjacent rubbing zones. Each of the ramps extends along a normal direction of the tool pan corresponding to the ramp and ramps up gradually towards a fringe of the corresponding tool pan. The driving element is connected with one of the tool pans to drive the tool pan to rotate relative to the other of the tool pans. 
         [0010]    The tool pan disclosed in the present invention comprises a plurality of homocentric annular structures. Each of the homocentric annular structures has a plurality of rubbing zones, and at least one ramp is disposed between adjacent rubbing zones. Each of the ramps extends along a normal direction of the tool pan and ramps up gradually towards a fringe of the tool pan. 
         [0011]    In an embodiment of the present invention, the rubbing machine further comprises a material-guiding screw, and one of the two tool pans has a material-guiding hole substantially located at a center of the tool pan, and the material-guiding screw is inserted into the material-guiding hole. 
         [0012]    In an embodiment of the present invention, each of the ramps near the fringe of the tool pan has a width that is smaller than which at positions away from the fringe of the tool pan. 
         [0013]    In an embodiment of the present invention, a plurality of ramps may be disposed between adjacent ones of the rubbing zones, and the ramps are arranged in a normal direction of the tool pan. 
         [0014]    In an embodiment of the present invention, each of the rubbing zones has a front end facing towards a direction in which the tool pans rotate relative to each other, and the front end has a chamfer. 
         [0015]    The tool pan of the rubbing machine of the present invention has ramps that are formed into a plurality of circles. In this way, the material to be rubbed can move between opposite rubbing zones along the ramps so that the material can be rubbed by the alternating forces between the two tool pans. As can be known from this, the rubbing machine of the present invention is applicable to the paper manufacturing industry where the fibers of herbage can be separated or fibrillated effectively by the mechanical force between the two tool pans. Thereby, it is unnecessary to use chemicals and this complies with the modem conception of environmental protection. 
         [0016]    What described above is only a summary of technical solutions of the present invention. In order to provide a better understanding of the technical means of the present invention so that the present invention can be practiced according to the present disclosure and in order to make the aforesaid and other objectives, features and advantages of the present invention clearer, preferred embodiments will be described hereinbelow with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic cross-sectional view of a rubbing machine according to an embodiment of the present invention; 
           [0018]      FIG. 2  is a schematic view of a tool pan according to an embodiment of the present invention; 
           [0019]      FIG. 3  is a schematic view illustrating a movement path of straws in the rubbing machine; and 
           [0020]      FIGS. 4A through 4D  are schematic views depicting how ramps impose forces on the straws. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    To further describe the technical means adopted by the present invention to achieve the predetermined objectives and the efficacies thereof, implementations, structures, features and efficacies of the rubbing machine and the tool pan thereof according to the present invention will be detailed as follows with reference to the attached drawings and the preferred embodiments. 
         [0022]      FIG. 1  is a schematic cross-sectional view of a rubbing machine according to an embodiment of the present invention, and  FIG. 2  is a schematic view of a tool pan according to an embodiment of the present invention. Referring to  FIG. 1  and  FIG. 2 , a rubbing machine  100  comprises a housing  110 , a tool pan assembly  120  and a driving element  130 . The housing  110  has a feeding inlet  112  and a discharging outlet  114 . The tool pan assembly  120  is disposed inside the housing  110  and comprises two tool pans  122 . The two tool pans  122  are spaced apart by an interval to form a rubbing space  128  that interconnects with the feeding inlet  112  and the discharging outlet  114  between the feeding inlet  112  and the discharging outlet  114 . 
         [0023]    Further, each of the tool pans  122  comprises a plurality of homocentric annular structures  125 . Each of the homocentric annular structures  125  has a plurality of rubbing zones  121 , and at least one ramp  127  is disposed between adjacent rubbing zones  121 . Each of the ramps  127  extends along a normal direction R of the tool pan  122  corresponding to the ramp and ramps up gradually towards a fringe of the corresponding tool pan  122 . In this embodiment, there are, for example, two ramps  127  arranged along the normal direction R of the tool pan  122  between every two adjacent rubbing zones  121  of each of the annular structures  125 . 
         [0024]    It shall be noted that, in other embodiments, there may also be more than two ramps  127  disposed between every two adjacent rubbing zones  121  of each annular structure  125 , and the number of ramps  127  disposed between every two adjacent rubbing zones  121  is not limited in the present invention. 
         [0025]    Particularly, each of the rubbing zones  121  may also have a chamfer  121   a  located at a front end of the rubbing zone  121 . Here, the terms “front” and “back” are defined with respect to a relative rotation direction of the tool pans  122 . That is, the chamfer  121   a  is located in the front with respect of the relative rotation direction of the tool pan  121   a.    
         [0026]    Furthermore, the rubbing zones  121  of the annular structures  125  in different annuli may be spaced apart by different intervals respectively in this embodiment. In other words, the ramps  127  of the annular structures  125  in different annuli may have different widths respectively. In this embodiment, the ramps  127  nearer to a fringe of the tool pans  122  have smaller widths. 
         [0027]    In this embodiment, only one of the two tool pans  122  rotates relative to the housing  110  while the other remains stationary when the rubbing machine  100  operates. However, the present invention is not limited to this; and in other embodiments, both the tool pans  122  can rotate relative to the housing  110  but rotate at speeds different from each other so that a relative movement takes place therebetween. 
         [0028]    In this embodiment, the tool pan  122  that can rotate relative to the housing  110  is connected with a rotary shaft  132  of the driving element  130  so as to be rotated by the driving element  130 . Specifically, the driving element  130  is a motor. On the other hand, the tool pan  122  that is stationary relative to the housing  110  may have a material-guiding hole  123  located substantially at a center of the tool pan  122  and communicating with the feeding inlet  112 . Moreover, the material to be rubbed that is fed from the feeding inlet  112  is transported into the rubbing zones  128  between the two tool pans  122  by use of a material-guiding screw  140  in this embodiment. To be more specific, the material-guiding screw  140  is inserted through the material-guiding hole  123  of the tool pan  122  and located below the feeding inlet  112  of the housing  110 . 
         [0029]    The rubbing machine of the present invention is applicable to the process of making paper pulp from plant fibers. To facilitate better understanding of the present invention by those skilled in the art, an application of the rubbing machine of the present invention will be described with reference to an embodiment thereof. 
         [0030]      FIG. 3  is a schematic view illustrating a movement path of a straw between the two tool pans. Referring to  FIG. 1  through  FIG. 3 , a straw of a herbaceous plant (e.g., a rice straw or a wheat straw) is obtained and processed by a pulper machine (not shown) to remove skins of the straw through vibration, and are then put into the feeding inlet  112 . Meanwhile, water is injected through the feeding inlet  112 . The straw then falls into spaces between threads  142  of the material-guiding screw  140  and, accompanying with the flowing water, is transported by the rotating material-guiding screw  140  from the material-guiding hole  123  to the rubbing spaces  128  between the two tool pans  122 ; and then under the action of a water flow caused by the centrifugal force resulting from rotation of the tool pan  122 , the straw is moved outwards radially to the ramps  127 . In this embodiment, the tool pan  122  shown in  FIG. 3  rotates in, for example, a clockwise direction, so the straw  200  moves outwards in a radial direction relative to the tool pan  122  but also in a slightly leftward direction. 
         [0031]      FIGS. 4A through 4D  are schematic views depicting how the rubbing zones impose forces on the straws. Referring to  FIG. 3  and  FIG. 4A  together, the straw  200  moves upwards along the ramps  127  under the action of the water flow. Because of the continuous relative rotation between the two tool pans  122 , the rubbing zones  121  of the two tool pans  121  move in directions indicated by the arrows in  FIG. 4A  respectively. Therefore, a force is applied to the straw  200  by the chamfers  121   a  located at the front ends of the rubbing zones  121  so that the straw  200  is pressed to move towards surfaces of the rubbing zones  121 . 
         [0032]    Next, as shown in  FIG. 4B , the rotation of the tool pan  122  drives the straw  200  into between chamfers  121   a  located at the front ends of the rubbing zones  121  opposite to each other. 
         [0033]    Then as shown in  FIG. 4C , with the continuous rotation of the tool pan  122 , the straw  200  is moved into between the opposite rubbing zones  121  by the chamfers  121   a.  At this point, because a gap between the opposite rubbing zones  121  is smaller than an original diameter of the straw  200 , a rubbing force is applied to the straw  200 . 
         [0034]    As shown in  FIG. 3  and  FIG. 4D , as the rubbing zones  121  of the two tool pans  122  move away from each other, the straw  200  moves out of the rubbing zones  121  into a next ramp  127  where the a fiber explosion phenomenon takes place due to an instantaneous vacuum effect. Thereby, the so-called separating or fibrillating of fibers can be achieved. 
         [0035]    For example, if an individual straw originally put into the rubbing machine is a fiber bundle consisting of multiple fine fibers, the straw can be separated into multiple fine fibers through the aforesaid process and this is just the so-called fiber separating. Moreover, if the straw originally put into the rubbing machine has already been separated into individual fine fibers, then the aforesaid process can have finer fibrils on the skin of the straw warped up and this is just the so-called fibrillating. The fibrillating is favorable for improving the intertwining force between fibers in the paper pulp to enhance the strength and toughness of the resulting paper. 
         [0036]    Taking the separating process as an example, the rubbing machine  10  of the present invention may also improve the fiber separating rate of each rubbing process by means of ramps  127  of different widths. In detail, as shown in  FIG. 3 , the original straw  200  floats up along a bottom surface of the ramp  127  of the innermost circle to a space between rubbing zones  121  of the two tool pans  122  where it is separated into fine fibers. Then, the fibers float up along a bottom surface of the ramp  127  of a next circle to a space between rubbing zones  121  of the two tool pans  122  where they are separated into finer fibers. In this way, by floating up along bottom surfaces of the ramps  127  of the different cycles to the spaces between the rubbing zones  121  of the two tool pans  122  repeatedly, the fiber separating rate of the straw can reach as high as 95%. Finally, a resulting pulp flows out from the discharging outlet  114 . 
         [0037]    According to the above descriptions, the tool pan assembly of the rubbing machine of the present invention has annular structures that are formed into a plurality of circles, and the annular structures comprise ramps that allow the material to be rubbed to float up into the rubbing zones between the two tool pans effectively so that the material can be rubbed by the alternating forces between the two tool pans. As can be known from this, the rubbing machine of the present invention is applicable to the paper manufacturing industry where the fibers of herbage can be separated effectively by the mechanical force between the two tool pans. Thereby, it is unnecessary to use chemicals and this complies with the modern conception of environmental protection. 
         [0038]    Furthermore, the rubbing machine of the present invention can also be used to fibrillate fine fibrils resulting from the separating process to improve the strength and toughness of paper made from the fibers. 
         [0039]    What described above are only preferred embodiments of the present disclosure, but are not intended to limit the present disclosure in any form. Although the present disclosure has been described above with reference to the preferred embodiments thereof, the preferred embodiments are not intended to limit the present disclosure. People skilled in the art can make slight alterations or modifications as equivalent embodiments on the basis of the above disclosures without departing from the scope of the present invention. However, any alterations, equivalent changes and modifications made to the above embodiments according to the technical spirits of the present disclosure and without departing from the scope of the present disclosure shall all be covered within the scope of the present disclosure. 
       INDUSTRIAL APPLICABILITY 
       [0040]    The rubbing machine of the present invention is applicable to the paper manufacturing industry where the fibers of herbage can be separated or fibrillated effectively by the mechanical force between the two tool pans. Thereby, it is unnecessary to use chemicals and this complies with the modem conception of environmental protection.