Abstract:
An apparatus for cleaning a part such as optical glass by an ultrasonic wave in a plurality of steps has a plurality of preset operation modes for an ultrasonic wave output strength and an ultrasonic wave cleaning time in each step so that one of the operation modes is selected in accordance with a property of the part to clean it in an appropriate manner.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to apparatus and method for cleaning an article by an ultrasonic wave in a plurality of steps, in which a cleaning condition is selectable in accordance with a property of the article. 
     2. Description of the Prior Art 
     A multi-stage ultrasonic wave cleaning apparatus which sequentially immerses an article to be cleaned into cleaning baths containing different cleaning solutions to clean the article in a plurality of steps has been known. 
     For optical glass, it is necessary to change the ultrasonic wave output strength and the ultrasonic wave radiation time in accordance with various conditions such as the material of the glass, glass the surface structure and types of cleaning solutions. Thus, the ultrasonic wave output strength and the cleaning time for each bath must be changed each time the type of the article to be cleaned is changed. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a multi-stage ultrasonic cleaning apparatus which can readily change the cleaning conditions of baths in the respective steps in accordance with a type of article to be cleaned. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of one embodiment of an ultrasonic cleaning apparatus of the present invention, 
     FIG. 2 illustrates conveyance of an article to be cleaned, and 
     FIG. 3, consisting of FIGS. 3a-3c, illustrates discrimination of an ultrasonic wave output strength by a convey carrier. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description, three articles to be cleaned, having low, intermediate and high resistances to an ultrasonic wave are handled in the apparatus of the present invention. 
     In FIG. 1, numerals 6a-6e denote ultrasonic cleaning baths in which cleaning liquids shown in the columns of the first to fifth steps in Table 1 are filled. The articles to be cleaned are sequentially immersed in the cleaning baths by an automatic conveyer and cleaned by the ultrasonic wave. Numeral 7 denotes an ultrasonic oscillator which oscillates in response to an applied ultrasonic wave oscillation wave. Numeral 3 denotes a control unit or controller which drives the ultrasonic wave oscillator 7 in one of three modes H, L and M. In the mode H, an article which has a high resistance to the ultrasonic wave is cleaned. When this mode is selected by a dial 10, the control unit 3 causes the ultrasonic wave oscillators 1a-1e to generate ultrasonic wave signals having outputs and duration shown in Table 1 and those signals are applied to the oscillators 7 of the ultrasonic cleaning baths 6a-6e. When the mode L or M is selected, the ultrasonic wave oscillation signals shown in the mode L or M in the Table 1 are supplied to the oscillators 7 of the ultrasonic wave cleaning baths 6a-6e. The drive times are shown in Table 1. They are set by an input keyboard 4 for the operation mode and the cleaning baths 6a-6e. The control unit 3 selects one of three oscillation signals supplied from the oscillators 1a-1e in accordance with the selected mode and supplies it to the oscillators 7 for a predetermined time period. Instead of switching being performed by the controller 3, the controller 3 may cause the ultrasonic wave generators 1a-1e to generate ultrasonic wave signals for the selected mode for the predetermined time period. In this case, the outputs may be adjusted by adjusting variable output transformers 2 of the ultrasonic wave oscillators 1a-1e. The selection of the mode L, M and H may be effected by the dial 10 or may be automatically effected as shown in FIG. 2. 
     FIG. 2 illustrates conveyance of the articles to be cleaned. A convey carrier 13 which carries the articles to be cleaned is conveyed by an entry conveyer 14 and a reflection type photo-electric sensor 15 selects one of the ultrasonic wave output strengths H, M and L to be applied to the articles and the selected signal is applied to an output selector 11, shown also in FIG. 1. The carrier 13 has apertures selectively formed therein and, as shown in FIGS. 3A-3C, the strength of the ultrasonic wave output is selected by the position of the aperture and the presence or absence of the aperture. In FIG. 3A where no aperture is formed, the high strength H is selected. In FIG. 3B where the aperture 17 is formed on the left hand, the middle strength M is selected. In FIG. 3C where the aperture 16 is formed on the right hand, the low strength L is detected. By additionaly forming apertures 16 to the left and right, four levels of strength may be provided. 
     The controller 3 selects the outputs from the ultrasonic wave oscillators 1a-1e by the signal from the sensor 15 and distributes the selected signal to the ultrasonic oscillators 7 of the cleaning baths 6a-6e. On the other hand, the carrier 13 is conveyed by an onto-conveyer to a cleaning unit 17 which includes the ultrasonic wave cleaning bath 6, a solution cleaning bath 8 shown illustratively as including two baths 8a and 8b and a distillation drying bath 9 and the articles conveyed into the ultrasonic wave cleaning baths 6a-6e are cleaned by the ultrasonic wave at the preset output and duration. After the ultrasonic wave cleaning, solution cleaning and drying, the carrier 13 is conveyed out of an exit conveyer 19. When a computer is used to set the settings 12 shown in FIG. 1, the characteristics of the article to be cleaned are previously analyzed and the ultrasonic wave output strengths and the radiation times are stored for each of the cleaning baths 6a-6e. 
     As described hereinabove, the ultrasonic cleaning apparatus of the present invention can clean the articles to be cleaned having various materials and surface structures by the cleaning baths containing appropriate liquids therein with proper ultrasonic sound output strength and radiation time. 
     
                                           TABLE 1__________________________________________________________________________  Mode L      Mode M      Mode H  Ultrasonic         Cleaning              Ultrasonic                     Cleaning                          Ultrasonic                                 Cleaning  Wave Output         Time Wave Output                     Time Wave Output                                 Time Cleaning  (KW)   (Sec)              (KW)   (Sec)                          (KW)   (Sec)                                      Solution__________________________________________________________________________1st Cleaning  0.42   13   0.45   12   0.5    11   Tetrachloro-Step                                       ethylene                                      (Cl.sub.2 C═CCl.sub.2)2nd Cleaning  0.32   12   0.4    11   0.48   10   Water and SurfaceStep                                       activating agentSolution                                   WaterCleaning Step3rd Cleaning  0.31   13   0.38   13   0.42   12   Water and surfaceStep                                       activating agent4th Cleaning  0.38   12   0.43   12   0.48   12   Pure WaterStep5th Cleaning  0.38   14   0.42   14   0.45   13   alcoholStepSolution                                   alcoholCleaning StepDistillation                               Trichloro-Drying Step                                trifluoroethylene                                      (CCl.sub.2 F--CClF.sub.2)__________________________________________________________________________