Patent Publication Number: US-2019193010-A1

Title: Filtering plate and method for making the same and filtering device having the same

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a filtering plate and a method for making the same and a filtering device having the same. 
     Description of the Prior Art 
     Waste plastic raw materials are first crushed and dried in a recycling granulation system, and then fed into a device having an extrusion screw and then heated to a certain temperature to be flowable. The flowable waste plastic materials then pass through a filtration system to filter out non-plastic materials. The filtered plastic materials are extruded out from a granulation plate, cooled and cut so that the filtered plastic materials are granulated. 
     The filtering plate of a conventional granulator is holed by mechanical processing to form a plurality of filtering holes, and the filtering holes are straight and of the same diametrical dimension. As a result, in addition to large discharge pressure, problem of obstruction of filtered materials can also be caused and it is not durable. In addition, since mechanical processing has a limit to form the small hole having a diametrical dimension not smaller than 0.3 millimeters, there is a known technique of obtaining smaller filtering holes by filtering layers layered. However, such conventional multi-layered filtering plate has more components, high costs, and poor structural strength due to the combined structure, and is easily obstructed and collects filth, because of the non-expanded filtering holes and gaps between the layers of the multi-layered filtering plate, so that there is a great discharge pressure caused. 
     The present invention is, therefore, arisen to obviate or at least mitigate the above mentioned disadvantages. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a filtering plate and a method for making the same and a filtering device having the same, in which the filtering plate is good in structural strength and provided with filtering holes each having a small diametrical dimension. 
     To achieve the above and other objects, a filtering plate is provided, including: a plate body, integrally formed of metal as one piece; a plurality of holed units, each holed unit penetrating the plate body and including a big hole and a plurality of small holes communicated with the big hole, the small hole being formed by laser processing and having a first end communicated with the big hole and a second end, the first end being greater than the second end in cross-sectional area. 
     To achieve the above and other objects, a filtering device is further provided, including at least one of filtering plate, further including: a main body, including a chamber, receiving the at least one filtering plate, the at least one filtering plate defining an infeed space and at least one discharge space in the chamber; a scrape device, including at least one scraper rotatably located at the second face of the filtering plate, configured for scraping residues on the second face. 
     To achieve the above and other objects, a method of making the above-mentioned filtering plate is further provided, including following steps of: providing the plate body; forming the plurality of large holes on the plate body by mechanical processing from the first face; using a laser, in a direction from the first face toward the second face, to form the plurality of small holes on a bottom face within respective one of the plurality of large hole in such a manner that a laser head projecting the laser is moved and kept in a fixed relative distance, wherein the fixed relative distance is defined as that on a basis of the second face the laser head is nonlower than the first face. 
     The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment (s) in accordance with the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a preferred embodiment of the present invention; 
         FIG. 2  is a side view of a preferred embodiment of the present invention; 
         FIG. 3  is a partial enlarged drawing of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view taken along line A-A  FIG. 1 ; 
         FIG. 5  is a partial enlarged drawing of  FIG. 4 ; 
         FIG. 6  is a partial enlarged drawing of  FIG. 5 ; and 
         FIG. 7  is a drawing showing a filtering device according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1-6  show a filtering plate according to a preferred embodiment of the present invention. The filtering plate  1  includes a plate body  10  and a plurality of holed units  20 . 
     The plate body  10  is integrally formed of metal as one piece and includes a first face  11  and a second face  12  in a widthwise direction thereof. Each of the plurality of holed units  20  penetrates the first face  11  and the second face  12  of the plate body  10 , and each of the plurality of holed units  20  includes a large hole  13  and a plurality of small holes  14  communicated with the large hole  13  and extends along the widthwise direction. Each of the plurality of small holes  14  includes a first end  141  and a second end  142 , and the first end  141  is larger than the second end  142  in cross-sectional area. Whereby, the filtering plate is good in structural strength and provided with filtering holes (the small holes  14 ) each having a small diametrical dimension. 
     In this embodiment, the large hole  13  is adjacent the first face  11 , the small hole  14  is adjacent the second face  12 , the first end  141  of respective one of the plurality of small holes  14  is connected with the large hole  13 , and the second end  142  of respective one of the plurality of small holes  14  is adjacent the second face  12 . It is noted that the term “adjacent” may be referred to “hole opening being aligned with the first face  11  or the second face  12 ” or “hole opening being lower or higher than the first face  11  or the second face  12 ”. In other embodiments, the second end of respective one of the plurality of small holes is connected with the large hole, and the first end of respective one of the plurality of small holes is adjacent the second face. 
     A distance between the first face  11  and the second face  12  is 1.5 to 6.0 millimeters. A number of the small holes  14  of each of the plurality of holed units  20  may be 800 to 1500. A distance between the first end  141  and the second end  142  is 0.2 to 3.5 millimeters. Preferably, the small hole  14  has a diametrical dimension of 0.03 millimeters at the first end  141 , and the small hole  14  has a diametrical dimension of 0.30 millimeters at the second end  142 . Preferably, the small hole  14  conically gradually expands from the second end  142  toward the first end  141 . In this embodiment, a distance between the first face  11  and the second face  12  is 5.5 millimeters, the large hole  13  has a diametrical dimension of 10 millimeters, and every adjacent two of large holes  13  have a spacing of 1.5 millimeters. A middle portion of the plate body  10  includes a central hole  15  larger than the large hole  13 , for mounting of a scrape device to the second face  12  for scraping residues of plastics or non-plastics on the second face  12 . The large hole  13  and the small hole  14  are preferably round, oval, polygonal or in other shapes. 
     In this embodiment, the large hole  13  of the plurality of holed units  20  form a plurality of hole layers  16 , and the plurality of hole layers  16  are disposed around the middle portion of the plate body  10  and between the middle portion and an outer periphery of the plate body  10 . Additionally, the large hole  13  of the plurality of holed units  20  form a plurality of hole rows  17 , and the large holes  13  of every adjacent two of hole rows  17  are alternatively arranged, thus evenly distributing material which passes through the filtering plate, lowering resistance of material passing through the filtering plate, and increasing filtering efficiency. In operation, plastic material comes into the large hole  13  from the second face  12  via the second end  142  of the small hole  14 , so that the small hole  14  which conically gradually expands is advantageous to filtering, and the plastic material will not jammed in the small hole  14 . 
     The plate body  10  may be formed of steel, alloy or the like with sufficient strength. In this embodiment, the large hole  13  is formed by mechanical processing, and the small hole  14  is formed by laser processing from the first face  11  toward the second face  12 . Mechanical processing can quickly produce the large hole  13  with the same diametrical dimension; however, mechanical processing has a limit to form the small hole having a diametrical dimension not smaller than 0.3 millimeters. As a result, the small hole  14  is preferably formed by laser processing because laser processing can precisely produce small hole which gradually expands without additional post-processing. 
     It is noted that in the laser processing, the laser head  40  projecting the laser is moved and kept a fixed relative distance relative to the first face  11  (maybe contact the first face  11 ). That is, the fixed relative distance is defined as that on a basis of the second face  12  the laser head  40  is nonlower than the first face  11 , and the laser head  40  scanningly projects the laser  41  on overall area of the first face  11  which includes all of the plurality of holed units  20 . As a result, there are holes formed, by the laser  41 , on the first face  11  and the bottom face of respective one of the large holes  13 , so that there is no need to further be positioned and focus on respective one of the large holes  13 , thus having good production yield. Since the laser  41  is set to focus on positions adjacent the bottom faces of the large holes  13 , there are shallow holes formed on a region of the plate body  10  except regions having the plurality of holed units  20 , and the small holes  14  are forming, in a naturally conical shape, on and penetrate respective bottoms of the large hole  13 . Preferably, surface treatment can be further carried out to remove the shallow holes, and thus the plate body  10  has a flat and smooth surface and is contamination-proof. 
     It is noted that the laser processing cannot proceed with only a limited thickness of the plate body  10 . As a result, if the plate body  10  is over-thick, the laser  41  cannot focus well, so it a poor laser processing result. The distance between the first end  141  and the second end  142  of the small hole  14  is preferably in a suitable range; otherwise it can results in bad penetration of the laser  41  through the plate body, and can form bad small holes. 
     Referring to  FIG. 7 , a filtering device  30  is further provided. The filtering device  30  includes at least one filtering plate  1  such as the aforementioned one, a main body  31  and a scrape device  32 . The main body  31  includes a chamber  311  and receives the at least one filtering plate  1 , wherein the main body  31  may be a base including the filtering device  30  and other peripheral apparatus or/and structures. The at least one filtering plate  1  defines an infeed space  312  and at least one discharge space  313  in the chamber  311 . Each of the at least one scrape device  32  includes at least one scraper  321  rotatably located at the second face  12  of the filtering plate  1  for scraping residues on the second face  12 , and a driving device (such as motor)  322  for driving the at least one scraper  321 . In this embodiment, a number of the at least one filtering plate  1  is two, a number of the at least one scraper  321  is two. The second faces  12  of the two filtering plates  1  separately face each other, and the second faces  12  of the two filtering plates  1  define the infeed space  312 . Preferably, between each filtering plate  1  and the inner face of the chamber  311  is a supporting plate  33 , thus improving supporting of the filtering plate  1  and avoiding deformation of the filtering plate  1 . The supporting plate  33  includes a plurality of through holes  331  communicated with the holed units  20  of the filtering plate  1  and the discharge space  313 . 
     The filtering device  30  further includes a discharge mechanism (such as dehydration granulator)  34  communicated with the infeed space  312 . The discharge mechanism  34  can extrude, through a structure such as a spiral blade structure  341 , the residues from the infeed space  312  out of the discharge mechanism  34 , and the extruded-out residues are then cut by a cutting mechanism  35 . 
     Given the above, the plate body is integrally formed of metal as one piece and good in structural strength; the small holes are directly formed on the plate body so that the manufacturing is quick and easy and so that it does not require separate parts to be respectively processed, holed and assembled; the small holes which are gradually enlarged facilitates filtering and discharging of materials, lowers the discharging pressure, decreases obstruction of materials, and increases durability. 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.