Patent Publication Number: US-2007095800-A1

Title: Surface treatment device

Description:
DESCRIPTION  
      1. Technical Field  
      The present invention generally relates to surface treatment devices, and more particularly to a device for treating surfaces of molds.  
      2. Description of the Related Art  
      With the increasing complexity and precision required in the manufacture of mold structures, current mold machining technologies are facing difficulties in meeting demand. Traditional mechanical machining methods and electrical discharge machining methods may not meet surface roughness requirements of modern precision molds.  
      A typical vibrating ultrasonic mold polishing apparatus is used to polish surfaces of a mold. The polishing apparatus includes an ultrasonic vibrator, an ultrasonic horn for amplifying vibrations, and a flexible element mounted on the ultrasonic horn for contacting with a surface of the mold to be polished. In the polishing process, a grinding material is positioned on the surface of the mold to be polished, and the flexible element is vibrated by amplified vibrations, thus creating friction between the mold surface to be polished and the grinding material. Thus, the surface of the mold is polished by the flexible element through the grinding material.  
      The typical polishing apparatus can be controlled to vibrate, and to achieve multi-angle polishing. However, the flexible element directly contacts with the surface to be polished in the polishing process. Therefore, the structure or size of the flexible element may directly affect the quality of polishing. In addition, it is very difficult to achieve satisfied polishing precision when the apparatus is used to polish a mold having fine and anomalous structures such as holes, grooves etc.  
      Therefore, it is desired to provide an improved apparatus that overcomes the above-described problems.  
     SUMMARY OF THE INVENTION  
      A surface treatment device includes a working platform, a laser source, a focus lens, a detector and a controller. The working platform is provided for supporting a workpiece thereon. The laser source is provided for producing laser beams. The focus lens is arranged at an appropriate position, i.e., between the working platform and the focus lens, for focusing the laser beams to a spot for treating the workpiece. The detector is provided for detecting information of the spot and generating a feedback signal corresponding to the detected information. The controller is electrically connected with the laser source, the working platform and the detector and configured for receiving the feedback signal from the detector to control emitting of the laser beams of the laser source and movement of the working platform.  
      Advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Many aspects of the present surface treatment device can be better understood with reference to the following drawing. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present surface treatment device. Moreover, in the drawing, like reference numerals designate corresponding parts throughout the view.  
       FIG. 1  is a schematic view of a surface treatment device, in accordance with a preferred embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      A mold machining apparatus for performing surface treatment, welding, cutting and other mold manufacturing processes is provided. Referring to  FIG. 1 , a surface treatment device  10  for treating surfaces of a mold is shown. The surface treatment device  10  includes a laser source  11 , a focus lens  13 , a working platform  14 , a detector  15  and a controller  16 . The laser source  11  is provided for emitting laser beams. The focus lens  13  is used to focus the laser beams from the laser source  11  to a spot for treating a workpiece to be machined. In order to advantageously focus the laser beams, a blocking shutter  12  is additionally provided. The blocking shutter  12  is positioned between the laser source  11  and the focus lens  13  for guiding laser beams to reach the focus lens  13 . The working platform  14  is provided to support the workpiece to be machined, such as a mold  17  to be machined, and is positioned at an appropriate place what the focused laser beams can treat the mold  17 . The detector  15  has a feedback end  151  and a detecting end  152 . The feedback end  151  is electrically connected with the controller  16 , and the detecting end  152  detects information of a treated spot of the laser beams on the mold  17 . The controller  16  is connected with the laser source  11  and the working platform  14 , for respectively controlling the laser source  11  and the working platform  14  after receiving a corresponding feedback signals from the detector  15 . The working platform  14  can be controlled to move or rotate in various desired direction. That is, according to the machining requirements, a location of the mold  17  can be controlled via adjust the working platform  14 .  
      The laser source  11  can be a solid-state laser source, and it can emit pulse laser beams. The laser source  11  may be a neodymium ion doped yttrium aluminum garnet (Nd-YAG) laser, a yttrium ion doped yttrium aluminum garnet (Yb-YAG) laser or a neodymium ion doped vanadate (Nd-YVO 4 ) laser. A wavelength of the Nd-YAG laser is about 1064 nanometers. A wavelength of the Yb-YAG laser is about 940 nanometers. A wavelength of the Nd-Vanadate laser is in a range from about 1047 nanometers to about 1064 nanometers.  
      The detector  15  detects information of the processing state and feeds back the detected signal corresponding to the detected information to the controller  16 . The controller  16  includes a first controlling unit  161  and a second controlling unit  162 . The first controlling unit  161  has a first end  161   a,  a second end  161   b  and a third end  161   c.  The first end  161   a,  second end  161   b  and third end  161   c  of the first controlling unit  161  are respectively electrically connected with the feedback end  151  of the detector  15 , the working platform  14  and one end of the second controlling unit  162 . The second controlling unit  162  further includes another end which is connected with the laser source  11  for controlling the emitting of the laser beams. Alternatively, the first controlling unit  161  and the second controlling unit  162  may be replaced by one controlling unit, if one controlling unit can respectively control the laser source  11  and the working platform through the detector  15 .  
      The surface treatment process may bring a great quantity of heat, a cooling system is desired to avoid heat distortion of the mold  17 . For example, the working platform  14  is a cooling device itself. That is, the working platform  14  defines a cavity  141  with a cooling solution  142  contained therein, and a seal plug  143  engages in an outlet of the cavity  141  for sealing the cooling solution  142 . Thus, during the surface treating process, the mold  17  can be continuously cooled by the cooling solution  142 . Alternatively, in the surface treatment process, the working platform  14  may be set in a cooling system, for example, in a cooling room.  
      The present surface treatment device  10  can precisely treating the surface of the mold  17 . Firstly, the surface of the mold  17  is treated by a focused light point. A dimension of the light point is very small (i.e. 1 micrometer to 10 micrometers across), thus, it can achieve satisfactory treating precision even if the surface of the mold  17  has fine and anomalous structures such as holes, grooves etc. Secondly, in the treating process, the dimension of the light point, the treating frequency of the laser beams, the desired roughness of the surfaces of the mold  17 , or other relative parameters all can be detected by the detector  15 , while the detected results are instantly fed back to the controller  16 . So, the controller  16  can instantly adjust the treating parameters to meet the process requirements.  
      A method for surface treating the mold  17  employing the aforesaid surface treatment device  10  is provided. The method includes the following steps: firstly, the mold  17  with a surface  18  to be treated is placed on the working platform  14 . Being controlled by the first controlling unit  161  of the controller  16 , the working platform  14  can move in any desired direction. The mold  17  can move together with the working platform  14 , thus it can be processed in various directions needed. The mold  17  may be comprised of nickel phosphide, stainless steel coated with nickel phosphide, aluminum alloys, magnesium alloys, aluminum-titanium alloys, and other metal or alloys.  
      Secondly, the laser source  11  is turned on for processing the surface  18  of the mold  17 . The laser source  11  is controlled to emit a desired frequency and quantity of the laser beams. The laser beams are adjusted by the blocking shutter  12 , and then are focused by the focus lens  13  to form an appropriately sized light point. In the present embodiment, the size of the light point can be adjusted from 1 micrometer to 10 micrometers. Such sized light points can process the surface  18  with high precision.  
      During the aforementioned treating process, the detector  15  instantly detects the size of the light point, and feeds back the detected result to the controller  16 . For example, the surface  18  has a number of regions to be treated, when the present region has been processed, and the processed result meets a determined requirement, a finishing signal generated by the detector  15  is transmitted to the first controlling unit  161 . The first controlling unit  161  then controls the working platform  14  to move to a next region to be treated, and a next treating process starts. However, once the processed result does not meet the determined requirement, or the size of the light point does not meet the surface treatment requirement, these failure information detected by the detector  15  are transmitted to the first controlling unit  161 . The first controlling unit  161  then transmits the failure information to the second controlling unit  162 , for adjusting the laser emitting parameters of the laser source  11 . When the present processing result or the size of the light point reaches the determined requirements, the laser source  11  will be controlled to retain the present working state.  
      The surface treatment device  10  can be used to polish surfaces of molds, or can be used to pattern some predetermined patterns on the mold surfaces. For super polishing or patterning by laser beams, surface roughness parameters, such as average roughness (Ra) and peak roughness (Rp) of the surface  18  of the mold  17  are determined by the following. The average roughness is in a range from about 0.2 nanometers to about 1 nanometer, the peak roughness is in a range from about 0.6 nanometers to about 3 nanometers.  
      In one example, to reach the above surface roughness parameters, the polishing parameters should fulfill the following conditions: the laser source is Nd-YAG laser, the pulse energy is in a range from about 10 micro-joules to about 30 micro-joules, the pulse duration is in a range from about 1 nano-second to about 5 nano-seconds, the repetition rate is in a range from about 1000 hertz to about 3000 hertz.  
      In another example, to reach the above surface roughness parameters, the patterning parameters should fulfill the following conditions: the laser source is Nd-YAG laser, the pulse energy is in a range from about 30 micro-joules to about 300 micro-joules, the pulse duration is in a range from about 10 nano-seconds to about 300 nano-seconds, the repetition rate is in a range from about 3000 hertz to about 10000 hertz. Therefore, employing a same laser source, the surface treatment device  10  can perform laser polishing and laser patterning processes, only requiring adjustment of the relative processing parameters. In addition, according to the laser polishing and laser patterning examples, in order to achieve an equal surface roughness degree, the process condition of the laser patterning process is more rigorous than that of the laser polishing process, for a patterned surface having a more finely surface structure.  
      It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.