Patent Publication Number: US-RE37120-E

Title: Parts send-out control device for vibratory parts feeder

Description:
TECHNICAL FIELD 
     The present invention relates to a parts send-out control device for a vibratory parts feeder to be used in the field of sending out parts such as projection nuts from the vibratory parts feeder. 
     BACKGROUND ART 
     As hitherto known, parts coming into the send-out passage of the vibratory parts feeder are sent out by force using jet air, and in this case the parts feeder is vibrating continuously. 
     In such constitution, the parts are continuously transferred from the bowl of the parts feeder into the send-out passage since the parts feeder is always vibrating, so that an excessive number of parts are accummulated ahead of the air nozzle, and hence they cannot be sent out completely with the jet force at the beginning of the air ejection. 
     DISCLOSURE OF THE INVENTION 
     The invention is contemplated to solve the above problem, being characterized by an air nozzle for ejecting conveying air in a send-out passage of a vibratory parts feeder, and a part detection sensor disposed in the send-out passage near the air nozzle, wherein the vibratory motion of the parts feeder is stopped and the conveying air is ejected from the air nozzle in response to a part detection electric signal transmitted by the part detection sensor. As a part sent into the send-out passage passes through the part detection sensor, it is detected and an electric signal is transmitted. Consequently, the vibratory parts feeder is stopped to suspend entry of parts into the send-out passage, and at the same time the conveying air is ejected to the part from the air nozzle toward that part, which is sent out to the desired position. 
     According to the invention, the part detection sensor is installed in the send-out passage near the air nozzle, and the air is ejected in response to the part detection signal from the part detection sensor, while the vibration of the parts feeder is stopped at the same time. Thus, the number of parts positioned ahead of the air nozzle can be limited so that the number does not exceed the air conveying capacity, ensuring the parts being sent out reliably. 
     The send-out passage is continuously installed at the terminal end of the spiral passage, and an air nozzle is attached to the end portion of the send-out passage. Hence the structure of the send-out portion of the bowl is simplified, and the direction of jet air can be set securely. Moreover, the air hose and part detection sensor are attached through the bracket welded to the tube member and the outer side of the bowl, resulting in the structure compact and functional. 
     According to another aspect of the invention, the send-out passage has a vent for allowing the air in the send-out passage in front of the parts to go out. The vent has silencing means, so that the jet air flow out of the vent is silenced by the silencing means. 
     When the silencing means is composed of porous permeation resisting member, not only resistance is given to the air jet to silence, but impurities such as oil and iron chips are captured by the porous member, and hence these impurities do not scatter outside, which is beneficial also from the viewpoint of sanitation of the working environments. 
     By thus installing silencing means at the vent of the send-out passage, any noise that would otherwise be made at the vent can be prevented. Being silenced by the silencing action of the porous sound absorbing member, wool-like sound absorbing material, expansion box, or conduit resistance by silencing hose, it is effective for improvement of working environments. Still more, the jet flow out of the vent is relaxed, and the air flow does not collide against the human body, and cold feel is avoided. As the oil, iron chips and other impurities are captures by the permeation resisting member, environmental contamination is prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial magnified plan view of the invention; 
     FIG. 2 is a plan view of a vibratory parts feeder; 
     FIG. 3 is a sectional view taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is a sectional view taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is a sectional view taken along line  5 — 5  of FIG. 1; 
     FIG. 6 is a sectional view taken along line  6 — 6  of FIG. 1; 
     FIG. 7 is a sectional view taken along line  7 — 7  of FIG. 1; 
     FIG. 8 is a schematic wiring circuit diagram; 
     FIG. 9 is a longitudinal sectional view showing an example of device for receiving parts from a parts feeder; 
     FIG. 10 is a longitudinal sectional view magnifying the silencing means in FIG. 9; 
     FIG. 11 is a longitudinal sectional view showing silencing means of other type; 
     FIG. 12 is a longitudinal sectional view showing silencing means of other type; 
     FIG. 13 is a longitudinal sectional view showing silencing means of other type; 
     FIG. 14 is a longitudinal sectional view showing silencing means of other type; and 
     FIG. 15 is a longitudinal sectional view in which silencing means is provided at other position. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Describing the invention in detail by referring to an embodiment in FIG. 1 to FIG. 8, a vibratory parts feeder  1  has an excitation unit  3  disposed at the lower side of a circular bowl  2  (FIG.  8 ), and a send-out passage  5  following a spiral passage  4  formed in the inner circumference of the bowl  2  (FIG.  2 ). The spiral passage  4  is of shelf-like stepped structure as seen from FIG.  3  and FIG. 4, and the send-out passage  5  square in cross section follows the terminal end of the spiral passage. The send-out passage  5  is formed by connecting a flexible send-out hose  7  made of synthetic resin to a metallic tube member  6 . The part  8  in this embodiment is a square projection nut as indicated by double dot chain line in FIG. 1 or as seen from FIG. 3, and has projections  9  for fusion welding formed integrally. 
     The spiral passage  4  is a little low at the outer side (FIGS. 3,  4 ,  5 ), and has a stopping groove  10  formed therein and terminating in or adjacent the send-out passage  5  (FIGS. 1,  3 ). A guide plate  11  is installed continuously from the terminal end of the stopping groove  10 , and an air nozzle  12  is fixed to its lateral side by welding or the like. The air nozzle  12  is set so that the air jet shoots in the longitudinal direction of the send-out passage  5 , and, through an air hose  13 , is connected to an air changeover valve  14  (see FIG.  8 ). To prevent the nut  8  on the spiral passage  4  from being inverted, eaves or an overhanging plate  15  is welded to the bowl  2  and is extended to the place along the tube member  6 , with a gap  16  being formed so that the internal nut  8  may be visible. 
     The nut  8  moving right side out on the spiral passage  4  is caught in the stopping groove  10  by its projections  9 , and is therefore moved sequentially by vibration as indicated by double dot chain line in FIG. 1, without dropping out in the outer circumferential direction of the spiral passage  4 . If the nut  8  is moving wrong side out, its projections  9  cannot be caught in the stopping groove  10 , and therefore it tumbles down to the outer side from the spiral passage  4 . To receive it and put back into the bowl  2 , a receiving box  17  is welded to the outer side of the bowl  2 , and a through hole  18  is formed in the outer plate of the bowl  2 . 
     An inverted L-shaped bracket  19  is welded to the tube member  6  and outer plate of the bowl  2  (FIG.  1 ), and the send-out hose  7  is supported by the bracket  19  from the lower side, and is tightened by a hat-shaped fitting  20  (FIG.  7 ). A fixing plate  21  folded downward is provided in the bracket  19  (FIG.  6 ), and a part detection sensor  22  is coupled thereto by means of bolts  23 . The part detection sensor  22  is in contact with the lower surface of the send-out hose  7 , and is as close to the air nozzle  12  as possible, and hence the air jet from the air nozzle  12  directly hits against the nut  8  at the position of the part detection sensor  22 , and the nut  8  is sent out forcibly. As a representative part detection sensor  22 , the proximity switch is most preferred herein, but a contact type limit switch or the like may be also used. 
     In FIG. 1, the part detection sensor  22  is shown as being supported by the bracket  19  coupled with the bowl  2 , but it may be also supported, for example, by a columnar support or the like set up on a stationary frame for mounting the parts feeder  1 . 
     FIG. 8 schematically shows wiring of related units, and the electrical relation of the units and the operation of the device will now be described with reference to this diagram. When the nut  8  is detected by the part detection sensor  22  and an electric signal is transmitted to the air changeover valve  14  through a wiring  24 , and the valve  14  opens to allow the air in the high pressure air source (not shown) to eject from the air nozzle  12 . As a result the nut  8  in the send-out passage  5  is sent out forcibly by the jet air. At the same time, the signal from the part detection sensor  22  is transmitted also to an excitation unit  26  of the parts feeder  1  through a wiring  25 , and the vibration of the parts feeder  1  is stopped, thereby limiting flow of parts into the send-out passage  5 . Meanwhile, FIG. 8 shows only the energization circuit of detection signal from the parts detection sensor  22 , but actually there is also a circuit of power current for driving the air changeover valve  14  and excitation unit  26 , and it is omitted herein because it is easily realized by an ordinary circuit. The bowl  2  is vibrated in the combined direction of vertical direction and circumferential direction by the excitation unit  26 , and hence the nuts  8  sequentially move on the spiral passage  4  as shown in FIG.  1 . When there are two or three nuts  8  between the air nozzle  12  and the part detection sensor  22 , they can be sent out by the jet air. If there are five or six or more parts, they can no more be fully conveyed by the air ejecting force, and therefore the vibration of the parts feeder  1  is stopped by the detection signal from the part detection sensor  2  so as to limit the flow of parts into the send-out passage  5 . 
     The end portion of the send-out passage  5  is connected to a desired position, that is, the device for receiving supply of parts (see FIG.  9 ). A control circuit may preferably be proviced, such that the number of parts existing immediately before the desired position is detected, and if, for example, five or six or more parts are detected an electric signal is transmitted for causing the excitation unit  26  to be inactive. 
     Referring now to FIG. 9 to FIG. 15, the silencing device will now be described. 
     FIG. 9 shows a parts feed device  30  of feed rod type as the device for receiving supply of parts from the parts feeder. A guide tube  31  is fixed to a stationary member  33  through a bracket  32 , and a feed rod  34  is retractably inserted in the guide tube. The feed rod  34  is composed of a large diameter end  35  and a small diameter end  36 . An air cylinder  37  is fixed to the upper end of the guide tube  31 , and its piston rod is coupled to the feed rod  34 . Welded to the lower end of the guide tube  31  is a curved metallic guide tube  38 . A guide plate  39  is welded to its end portion, thereby forming a temporary retention chamber  40 . A magnet  41  is fitted into the guide plate  39 . The part, which is a projection nut  42 , is attracted and held by the magnet  41  in the chamber  40  with its screw hole coaxial with the small diameter end  36 . 
     On an extension of the direction of advancement of the feed rod  34 , a guide pin  57  of a stationary electrode  56  is positioned, and this guide pin  57  is fitted into the through hole in the steel plate part  58  mounted on the stationary electrode  56 , thereby positioning a steel plate part  58 . When the feed rod  34  is advanced from the state as shown, the small diameter end  36  penetrates into the screw hole of the nut  42  to be extended close to the guide pin  57 , thereby guiding the nut  42  to move toward the guide pin  57 . 
     One end of a feed hose  43  square in cross section is connected to the guide tube  38 , and the other end thereof is connected to a send-out tube  44 . The feed hose  43  is made of a flexible synthetic resin material, and has a sectional passage area for allowing the square nut  42  as shown to pass therethrough while leaving a slight gap. The dimensions of the nut  42  are, for example, 12 mm by 12 mm and 6 mm high. A parts feed conduit  45  is composed by the internal passages of guide tube  38 , feed hose  43 , and send-out tube  44 . This parts feed conduit  45  corresponds to the send-out passage  5  previously referred to. A nozzle tube  46  is welded to the send-out tube  44 , and its injection hole  47  is opened in the send-out tube  44 , and an air hose  48  is connected to the nozzle tube  46 . 
     By the jet air from the injection hole  47 , a conveying force is given to the nut  42 , and as the nut  42  moves, the air in the parts feed conduit  45  in front of the nut is exhausted from an exhaust hole or vent  49 , so that the nut  42  is moved smoothly. This vent  49  has silencing means  50 , and a mounting member  51  of a pi-section is fitted to the outside of the feed hose  43 , and is tightened by the fixing band  52 . The silencing means  50  is fixed to the mounting member  51  and hence communicates with the vent  49 . 
     The silencing means  50  in FIG. 9 is magnified in FIG. 10, and explaining more specifically, a joint tube  53  is screwed into the mounting member  51  at a threaded part  54 , and a cup-shaped porous permeation resisting member  55  is tightly fitted into the joint tube  53 . As the permeation resisting member  55 , metal wool densely packed into a cup shape, or sintered alloy may be used, among others, though, the illustrated example is in the form of a sintered porous material of fine spherical granules of copper alloy. 
     Explaining the action of the embodiment, when the nut  42  is moved by the jet air from the injection hole  47 , the air in the parts feed conduit  45  ahead of the nut  42  is exhausted by force from the vent  49 , and the air passes through the porous permeation resisting member  55  at this time, and the flow of air is reduced in the whole range of the member  55  and is silenced. Therefore, the flow of air is uniformly dispersed by the member  55  without jet stream from the vent  49  as experienced in the prior art. 
     Modified examples of silencing means are shown in FIG.  11  and after. Referring first to FIG. 11, a permeable foam body  59  is adhered so as to close the vent  49 , and it acts same as the permeation resisting member  55 . The foam body  59  is composed of synthetic resin sponge material. 
     In FIG. 12, a silencer box  60  having a plurality of through holes  61  is welded to the joint tube  53 . The box  60  is filled with sound absorbing material  62 . Steel wool or the like may be suited as sound absorbing material  62 . This wool corresponds to the porous material. The air from the vent  49  is discharged uniformly out of the through holes  61 , while being silenced by the sound absorbing action of the sound absorbing material  62 . 
     In FIG. 13, an expansion box  63  having a through hole  64  is welded to the joint tube  53 . The exhaust gets into the expansion box  63  and expands suddenly, resulting in a decrease in kinetic energy and reduction of the sound made by the exaust. 
     In FIG. 14, an elongate silencer hose  65  is connected at one end thereof to the joint tube  53  and the other end thereof is disposed at a position remote from the operator. The air from the vent  49  is subjected to conduit resistance while passing through the silencer hose  65 , and is hence silenced as desired. In this embodiment, the silencer hose may be bent in a free form and laid out as desired. 
     In FIG. 15, the silencing means  50  as shown in FIG. 10 is provided in the guide tube  38  in FIG. 9, and the silencing action is same as in FIG.  9  and FIG.  10 . 
     Either one silencing means  50  may be provided as shown in the drawings, or a plurality may be installed depending on the necessity. Or if the silencing means is clogged with impurities such as oil and iron chips, it may be cleaned in gasoline or volatile oil, and may be used repeatedly.