Patent Publication Number: US-2011061999-A1

Title: Non-contact type of vacuum pad

Description:
TECHNICAL FIELD 
     The present invention relates, in general, to a vacuum pad which is utilized for holding an article in a vacuum conveying system and, more particularly, to a non-contact type vacuum pad which is capable of holding an article in a non-contact state. 
     BACKGROUND ART 
     A vacuum conveying system is a system that creates negative pressure in a vacuum pad using compressed air and uses the created negative pressure to hold an article so that it can be conveyed to a predetermined place. It is common to use a contact type vacuum pad in this system. However, the contact type vacuum pad is problematic in that it is in direct contact with a surface of the article, so that its surface becomes damaged or contaminated. 
     Especially, a panel or the like used for a display of an electronic product is susceptible to fine scratches or deformation or impurities, so that the contact type pad is unsuitable for conveying the article. Thus, recently, the demand for a non-contact type pad is gradually increasing. 
     Conventional non-contact type vacuum pads are illustrated in  FIGS. 1 and 2 . The same reference numerals are used in the two drawings to designate the same or similar components. As shown in the drawings, each non-contact type vacuum pad includes a main body  1  which has in a central portion thereof a compressed-air supply hole  2 , and a guide  3  which is coupled to the lower portion of the main body  1 , thus guiding the flow of air in a lateral direction. 
     The compressed air, which is supplied through the supply hole  2  of the main body  1  into the vacuum pad, is guided in the lateral direction by the guide  3 , and passes through the edge of the lower surface of the main body  1  at high speed to be discharged to the outside. At this time, according to the Bernoulli effect, a vacuum is created between the vacuum pad and an article P, and negative pressure is generated by a difference in pressure between the vacuum and the atmospheric pressure. 
     The negative pressure causes the article P to come in proximity to and be held by the vacuum pad. However, a non-contact state is maintained between the vacuum pad and the article P, because they are spaced apart from each other by a minimum gap d by the discharge pressure of the compressed air. For this reason, it is called a non-contact type vacuum pad. 
     When comparing the non-contact type vacuum pad with the contact type pad, the non-contact type vacuum pad is considerably advantageous in the handling of an article that needs to maintain a precision surface. However, this type of vacuum pad is problematic in that there is a limitation with respect to the vacuum strength that can be achieved, and it takes a long time to reach the maximum of the strength. Thus, it is not reliably used to handle an article that is heavy. 
     For example, the non-contact type vacuum pad may obtain a higher vacuum strength by supplying a larger amount of compressed air at higher speed, and discharging the compressed air at higher speed. However, in this case, there is an excessively large amount of energy consumed. 
     As another prior art, a non-contact type gripper is disclosed in Korean U.M. Registration No. 401259. The gripper includes a vacuum hose which passes through a non-contact pad corresponding to the guide  3  and extends to the outside. Although not explained therein, the vacuum hose is connected to a separate vacuum pump. 
     In the gripper, the vacuum pump is driven so that air present underneath the non-contact pad is forcibly discharged. Thus, compared to the non-contact type vacuum pad, the gripper can more rapidly obtain a stronger vacuum. However, the gripper is problematic in that it requires a complex design including the vacuum hose, its mounting structure, and the vacuum pump. Further, the gripper is problematic in that energy for driving the vacuum pump as well as energy for holding an article is required. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a vacuum pad, which is capable of obtaining a reliable level of negative pressure and a reliably strong vacuum when handling an article that is heavy. 
     Another object of the present invention is to provide a non-contact type vacuum pad, which can improve energy efficiency using a simple design, thus being very advantageous in an economic point of view. 
     Technical Solution 
     In order to accomplish the above objects, the present invention provides a non-contact type vacuum pad including a main body, an air guide, and a discharge passage defined by the main body and the guide. The main body has a compressed-air supply hole formed in a central portion thereof, and an outwardly flared surface formed on a lower end of the supply hole. Such a construction is not different from the conventional vacuum pad. 
     The air guide is mounted to the main body in such a way that the air guide does not protrude from a bottom edge of the main body, and has a central inflow recess which communicates with the supply hole, at least one flow pathway which is formed from the inflow recess through a wall surface, and a suction hole which extends from a bottom surface and is connected to the flow pathway. Further, the discharge passage is the passage through which compressed air supplied to the supply hole is discharged, and extends from the flow pathway of the guide to the flared surface and the edge of the main body, 
     Preferably, the flow pathway may comprise a plurality of flow pathways which are radially arranged around the inflow recess. More preferably, each flow pathway may comprise flow pathways which are arranged in series and in multiple stages. The suction hole may be formed between neighboring flow pathways. The suction hole may have an annular shape. Preferably, the suction hole may have on a lower end thereof a flared surface. Such a construction is useful for rapidly and smoothly sucking in outside air. 
     Further, preferably, a lower surface of a middle portion of the guide may be placed to be further inside than a lower surface of an outer portion of the guide. Such a configuration provides a larger vacuum space as compared to the configuration wherein the lower surface of the central portion of the guide is on the same level with the lower surface of the outer portion, thus attaining a larger vacuum space, therefore obtaining a stronger vacuum and greater holding force. 
     ADVANTAGEOUS EFFECTS 
     According to the present invention, a vacuum pad is advantageous in that, when compressed air passes through a discharge passage at high speed, outside air present underneath the vacuum pad is sucked in and then is discharged along with the compressed air, so that a higher vacuum strength is more rapidly achieved. Thus, the vacuum pad is advantageous in that it can be reliably applied when handling an article that is heavy. Meanwhile, in order to accomplish the effect, a complex design, a larger amount of energy or an additional energy source are not required. Therefore, the vacuum pad is very advantageous in terms of economics and energy efficiency. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view showing a conventional non-contact type vacuum pad; 
         FIG. 2  is a sectional view showing another conventional non-contact type vacuum pad; 
         FIG. 3  is a sectional view showing a non-contact type vacuum pad according to the present invention; 
         FIG. 4  is a bottom view showing an air guide applied to  FIG. 3 ; and 
         FIG. 5  is a view illustrating the operation of the non-contact type vacuum pad according to the present invention. 
     
    
    
     DESCRIPTION OF REFERENCE CHARACTERS OF IMPORTANT PARTS 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 11. main body 
                 12. guide 
               
               
                   
                 13. supply hole 
                 14. flared surface 
               
               
                   
                 18. flow pathway 
                 19. suction hole 
               
               
                   
                 20. flared surface 
               
               
                   
                   
               
            
           
         
       
     
     MODE FOR INVENTION 
     The above or other characteristics and effects of the present invention may be more obvious based on the description of the embodiment of the present invention which is illustrated below with reference to  FIGS. 3 to 5 . 
     Referring to  FIG. 3 , a non-contact type vacuum pad of the present invention is denoted by reference numeral  10 . The vacuum pad  10  includes a main body  11 , a guide  12  which is coupled to the lower portion of the main body  11 , and a compressed-air discharge passage which is provided between the main body  11  and the guide  12 . Here, the main body  11  has a compressed-air supply hole  13  which is formed in the central portion of the main body, and an outwardly flared surface  14  which is formed on the lower end of the supply hole  13 . The construction is not different from that of the conventional vacuum pad. However, the outwardly flared surface may be selected from an inclined surface or a round surface. 
     The air guide  12  is mounted to the main body  11  in such a way that it does not protrude from a bottom edge  15  of the main body. Preferably, the air guide is mounted to the main body  11  in such a way that it does not protrude from the outwardly flared surface  14  formed on the lower end of the supply hole  13 . For example, if the guide  12  protrudes, the vacuum pad  10  may make contact with an article ‘P’ (see  FIG. 5 ). 
     The air guide  12  includes a central inflow recess  16  which communicates with the supply hole  13 , at least one flow pathway  18  which is formed from the inflow recess  16  through a wall surface  17 , and a suction hole  19  which extends from a bottom surface and is connected to the flow pathway  18 . Although not shown in the drawings, a pipe-type nozzle may be mounted to the flow pathway  18 . 
     The discharge passage is the place through which compressed air supplied to the supply hole  13  of the main body  11  is discharged, and extends from the flow pathway  18  of the guide  12  to the flared surface  14  and the edge  15  of the main body  11 . 
     Referring to  FIG. 4 , a plurality of flow pathways  18  is formed in the guide  12  to be radially arranged around the inflow recess  16 . If there are too many flow pathways  18 , the speed at which the compressed air is discharged may be reduced. In order to solve the problem, it is necessary to ascertain what is the proper number of flow pathways. In the drawing, the suction hole  19  has the shape of one ring and communicates with each flow pathway  18 . Such a construction is useful for rapidly and smoothly sucking in outside air, namely, air between the vacuum pad  10  and the article ‘P’ (see  FIG. 5 ). 
     Each flow pathway  18  comprises flow pathways  18   a  and  18   b  which are arranged in series and in multiple stages in such a way that their diameters are increased. The suction hole  19  is placed between neighboring flow pathways  18   a  and  18   b . Compressed air passes through the flow pathway  18   a  having a small diameter at the highest speed. Hence, outside air is introduced into the compressed air through the suction hole  19 . Further, the outside air is combined with the compressed air at the flow pathway  18   b  having a large diameter and then discharged together with the compressed air. Such a shape of the flow pathway  18  is very effective in discharging the outside air. 
     Turning back to  FIG. 3 , the suction hole  19  has on the lower end thereof a flared surface  20 . Such a construction is useful for rapidly and smoothly sucking in outside air underneath the vacuum pad  10 . Meanwhile, a lower surface  21  of a middle portion of the guide  12  is placed to be further inside than a lower surface  22  of an outer portion thereof. Such a configuration provides a larger vacuum space in comparison with the configuration wherein the lower surface of the middle portion is on the same level with that of the outer portion. Thus, the vacuum pad  10  can attain a stronger vacuum and a greater holding force. 
     The lower surface  22  of the outer portion of the guide  12  extends and protrudes leftwards and rightwards. This guides the compressed air such that it is naturally discharged along the flared surface  14  after passing through the flow pathway  18 . 
     Referring to  FIG. 5 , compressed air is supplied to the supply hole  13  of the main body  11 , and flows into the inflow recess  16  of the guide  12 . The compressed air then in sequence passes through the discharge passage, that is, the flow pathway  18 , the flared surface  14 , and the edge  15  and then is discharged to the outside (see arrows  24 ). 
     In this process, Bernoulli&#39;s effect is in effect. That is, some of the air present between the vacuum pad  10  and the article P is combined with the compressed air in the vicinity of the flared surface  14  and is discharged together with the compressed air (see arrows  25 ). Simultaneously, other air between the vacuum pad  10  and the article P passes through the suction hole  19 , is introduced into the compressed air, and is combined with the compressed air at the flow pathway  18   b  to be discharged together with the compressed air (see arrows  26 ). 
     Thereby, vacuum and negative pressure are generated between the vacuum pad  10  and the article P, and the generated negative pressure causes the article P to come in proximity to and be held by the vacuum pad  10  (see arrows  27 ). 
     The above-mentioned vacuum pad  10  is constructed so that, when the compressed air passes through the discharge passage, the outside air existing underneath the vacuum pad is introduced into the compressed air in the vicinity of the flared surface  14  and through the suction hole  19 , and is combined with the compressed air to be discharged together with the compressed air. Therefore, a very strong vacuum and negative pressure can be more rapidly created. Further, it is obvious that a complex design, a large amount of energy or an additional energy source are not required to accomplish the rapid creation of a strong vacuum and strong negative pressure.