Full text: XVIIth ISPRS Congress (Part B5)

    
   
   
    
  
    
   
  
  
  
  
     
  
     
    
    
    
    
   
  
      
    
    
  
    
    
  
     
    
   
     
     
      
RESEARCH ON THE DETECTION OF CUTTING TOOL WEAR BY MACHINE VISION 
Mei Anhua Wang Jinhui 
Optical Instrument Department, W. T. V of Surving and Mapping 
This paper presents a method of applying a system which consists of an Optoelectronic scanner(TV camera or CCD) and 
an IBM/pc computer to obtain the micrograph information from the worn region on the flank of the cutting part of the tool 
and analyze and process the picture by means of imagine processing and mode recognizing technology. The on-line and off- 
line methods are used respectively to calculate accurately the worn value, recognize the form of wearing and forecast the 
tool life.At the last, the optimum valued of cutting velocity and feed are given, which meet the principle of the lowest cost 
and longest tool life It is proved by experiments that the conclusion of the theoretical analysis and calculation agrees 
with the practical test, Thearticle provides a practical and precise way of checking and controling cutting tools on Line. 
Keyword: Machion Vision, Cutting tool, Wear 
  
1.0btaining the wear imagine on the flank of 2.2 Extracting the edge of wear region 
cutting tool ; 
Cutting tool will be worn after being used. The According to the character of geometric state and 
worn region appears around the corner. There are two the value of the wear, the wear type could be 
kinds of wear: the face wear and the flank wear. In recognized, The precision and reliability of 
theory and practice, the flank wear is widely used. recognition relys on the measuring precision for the 
So, in this research, we collect, process and wear geomety. This research improves mesuring 
analyce the flank wear imagine of cutting tool. The precision by means of making binary image, extracing 
system which has been used in the reseach shows in the edge of worn region on binary picture and 
Finl.1. gauging the edge. 
Selecting threshold is a impartant step of making 
binary image. When the wear picture is being taken 
by microscope and TV camera, the flank’s wear area 
  
L ht Source is on the centre of the field of microscope, In the 
i picture, there are three parts: worn area, unworn 
area of the flank and other's parts(back ground) . 
T V There are deferent gray level in three prats. 
x | WwüCx, y? is defined to the gray level function of 
Camera. Microscope background. ww0(x,y) is distributed equally over the 
background area Cw0). ; 
The unworn part of the flank reflects partly light 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
E ud and shines higher than the background when lighted 
m en by incandestent lamp. We definite it’s gray level 
P Picture Cutting fnuction as Gwl(x,y), which is distributed over the 
286 Monitor area, Showed as wi, 
Tool The worn prat of flank reflect light strongest in 
  
  
  
the three parts of a picture, It’s gray level 
function is Hw2(x,y), which is distribute over the 
X area showed by w2. 
3 ^f Level function of the image can be described as: 
W (x,y) x, yEw0 
t Gvpz(6 esp xjy€wl (2-D 
H GOGy) xy€w2 
The system consists of TV Camera, microscope(C30^, Obviously, 
Computer and picture monitor. The micrograph has HCx, y)>GCx, y)>WCx, y) (2-2) 
been obtained by the system, which is showed Fig, lof Therefore, the gray level histogram of the image 
the appendix, In the micrograpl, the worn region is is showed as Fig. 1.2 
closed and irregular. Because of using incandescent 
lamp for lighting, light affects directly the 
clarity of the picture and gauging precise, In order 
to prove gauging precise, the light source must be 
adjust carefully to make high reflecting Light on 
wear region so the distingush in worn region and 
unworn region are very clear, the imagine must be 
reprocessed with smoothing and filtering methods, 
before being gauged. 
——— 
  
  
2.Preprocessing micrograph and extracting the edge, 
Number of Points 
2.1 Preprocessing: 
  
  
Because incandescent is not distriluted equally 
over the flank of cutting tool, the quality of the 
pictures are affected and much disturbance takes Gray Value 
place in the picture, So the picture must be 
processed by mediom filter method to cancel the 
disturbance and make the edge of the wear region From these, we can choice the threshold for making 
clear, After filtering, the gray level histogram can binary image, The binary image has been made that 
be made to prepare choising the thresholding, shows as the Fig.2 in appendix, 
which is the key of making binary picture, The edge of the worn area can be produced by the 
methods of scanning, extracting and thinning. The 
 
	        
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