Vacuum pallet type screen printing machine with registration means

Abstract

This disclosure is directed to a pallet type screen printing machine in which a pallet is indexed to a printing station when an article supported thereon is screen printed. A feed table with guides is cooperatively disposed relative to the pallet at a feed station to facilitate the accurate positioning of a work piece onto the pallet. The machine comprises an endless drive for effecting movement of one or more pallets to and from a printing station in an endless path whereby the face of the pallet is always maintained in a face up position. The pallet is formed to define a vacuum chamber which is operatively connected to a source for drawing a negative pressure thereon. A flexible coupling operatively connects the pallet to the endless drive to permit limited movement of the pallet so that the pallet may be brought into accurate registration with the printing head at the printing station. Registration of the pallet in the printing station is effected by a locating cam and a cooperatively associated cam follower, which when activated, will effect the required alignment and registration of the pallet with the printing head.

What is claimed is: 
     
       1. A screen printing machine comprising a frame,   a printing head defining a printing station mounted on said frame,   a track means on said frame extending along the length of said frame,   a pallet means movably mounted on said track,   said pallet means including spaced apart upper and lower plates and connected end walls defining therebetween a vacuum chamber,   said upper plate having a series of apertures formed therein,   means connected to said pallet means for drawing a vacuum on said chamber,   spaced apart roller means connected to said pallet means disposed in rolling contact with said track means,   a flexible endless drive disposed along each side of said frame,   said endless drive including an upper flight and a lower flight,   a flexible coupling connecting said pallet means to each of said endless drivers,   motor drive means connected to said endless drive to effect the actuation thereof for moving the connected pallet toward and away from said printing station,   means for effecting registration of said pallet means with said printing head when in the printing station,   and transfer means adjacent each end of said endless drives for effecting movement of said pallet means between said upper and lower flights, said transfer means always maintaining said pallet means face up.   
     
     
       2. The invention as defined in claim 1 and including an electric track, and a sliding contact engaging said electric track,   said contact being connected in circuit to said vacuum drawing means, whereby said latter means is energized when said sliding contact is disposed in electrical contact with said track.   
     
     
       3. The invention as defined in claim 1 wherein said registration means includes a locator having a notch carried on said pallet means, and a cooperating follower positioned on the frame to engage said locator notch,   and means for activating said follower.   
     
     
       4. The invention as defined in claim 1 wherein said transfer means includes a transfer sprocket adjacent one end of said machine, and a transfer guide means at the other end of the machine,   means formed on the periphery of said transfer sprocket for receiving said rollers whereby said sprocket when engaged by said rollers functions to transfer said pallet means, face up, between said flights.   
     
     
       5. The invention as defined in claim 1 and including indexing means connected to said motor drive means to limit the movement of said pallet means to said printing station. 
     
     
       6. The invention as defined in claim 1 and including means for decelerating the speed of said motor drive means as said pallet means approaches said printing station. 
     
     
       7. The invention as defined in claim 1 wherein said pallet means includes roller means, and said transfer means at one end of said flight comprising: a transfer sprocket,   means for driving said transfer sprocket in unison with said drive means,   said transfer sprocket having means formed about the periphery thereof for engaging the roller means connected to said pallets, whereby said transfer sprocket co-acts with said drive means to lift said pallets from the lower flight to the upper flight.   
     
     
       8. In a screen printing machine including a frame having a feed end, and a screen printing head mounted on said frame for movement between printing and non-printing .[.position.]. .Iadd.positions.Iaddend., the improvement comprising: pallet means, said pallet means having an upper and lower member defining a chamber therebetween, said upper member having apertures formed therein,   a drive means for effecting the movement of said pallet means toward and away from a printing station located below said printing head,   said drive means comprising an endless flexible drive moving in an endless path along spaced apart upper and lower flights,   means connecting said pallet means to said endless flexible drive to be driven along said endless path,   transfer means disposed adjacent the opposed ends of said endless path for effecting the transfer of said pallets between said flights, said transfer means maintaining said pallets in a face-up position throughout the travel thereof along said endless path,   a vacuum producing means connected to the chamber of said pallet means for drawing a negative pressure on said chamber as said pallet means moves along said endless path,   a registration means operatively associated with said pallet means for effecting registration of said pallet means with said printing head when in the printing position beneath said printing head.   
     
     
       9. The invention as defined in claim 8 wherein said pallet connecting means includes .[.a.]. resilient coupling .Iadd.means .Iaddend.to provide for limited relative movement between said pallet means and .[.its.]. .Iadd.said .Iaddend.flexible drive. 
     
     
       10. The invention as defined in claim 9 wherein said drive means includes: a pair of spaced apart endless flexible driving means extending along the longitudinal sides of said frame,   said resilient coupling means comprising opposed connecting links disposed .[.to.]. .Iadd.on .Iaddend.opposed sides of said pallet,   one end of said link being connected to the adjacent flexible drive means,   a resilient bearing member connected to the other end of said link, .Iadd.and .Iaddend.   .[.and.]. a bearing housing connected to the sides of said pallet means for receiving said resilient bearing member.   
     
     
       11. The invention as defined in claim 9 wherein said drive means .[.including.]. .Iadd.include .Iaddend.a pair of opposed endless flexible drives, said pallet .Iadd.means .Iaddend.being disposed between said flexible drives, said resilient coupling means .[.are.]. being oppositely disposed on said pallet means to form a connection with the respective endless drives whereby said flexible drives pull said pallet .Iadd.means .Iaddend.therebetween to and from a printing station when actuated,   .[.and.]. said registration means comprising a locating means connected to said pallet  .[.and.].,   a complementary follower positioned on the frame to engage said locating means, .Iadd.and .Iaddend.   .[.and.]. means for activating said follower to effect registration of said pallet means in the printing station.   
     
     
       12. The invention as defined in claim 8 and including a feed table disposed to one side of the pallet means at the feed end of said machine, said feed table extending slightly over the side of said pallet means in overlying relationship thereto, .Iadd.and.Iaddend.   .[.and.]. means on said table for properly orientating a work piece on said pallet means whereby the work piece is partly supported on said feed table and partly on said pallet means at the feed end.   
     
     
       13. The invention as defined in claim 8 wherein said pallet means includes roller means, and said transfer means at one end of said flight comprises a transfer guide means positioned to receive the roller means of said pallet.[.,.]. and to cooperate with said drive means for effecting transfer of said pallet means between the upper and lower flight in said face-up position. 
     
     
       14. The invention as defined in claim 8 and including means for maintaining said vacuum producing means actuated as said pallet means is moved toward and away from said printing station. 
     
     
       15. In a screen printing machine having a frame and a plurality of printing heads mounted on said frame to define a plurality of printing stations, each of said printing heads being adapted to support a printing screen and an associated squeegee, the improvement comprising, a plurality of pallet means supported on said frame by drive means having endless vertically spaced .[.aparts.]. .Iadd.apart .Iaddend.flights,   said endless drive means for effecting the movement of said pallet means from station to station along said flights in an endless path,   means for flexibly coupling each of said pallet means to said endless drive means at spaced intervals along said endless drive means,   means for effecting the registration of said pallet means with its respective printing head when disposed in said printing stations,   each of said pallet means including spaced apart upper and lower members defining a chamber therebetween, said upper member having apertures formed therein,   a vacuum producing means connected to each of said pallet means for drawing a negative pressure on the associated pallet chamber,   means for maintaining said vacuum producing means activated as said pallet means advances through the respective printing stations, .Iadd.and.Iaddend.   .[.and.]. transfer means adjacent each end of said endless path for maintaining said pallet means in a face-up position through the entire travel thereof about said endless path.   
     
     
       16. The invention as defined in .Iadd.claim .Iaddend.15 wherein said endless drive means comprises: opposed flexible endless drives extending along the adjacent longitudinal sides of said frame, .[.and.].   said flexible coupling means including oppositely disposed links,   a resilient bearing connected to one end of each of said links, said resilient bearing being coupled to said pallet means,   .[.and.]. said registration means including a locator on each of said pallet means and an associated follower located on said frame at each printing station, .Iadd.and .Iaddend.   means for activating said follower to effect registration of said follower with said locator on said pallet means in a printing station.   
     
     
       17. The invention as defined in claim 16 wherein the direction of movement of said follower is substantially normal to said locator on said pallet means. .Iadd. 18. In a screen printing machine having a frame, a screen printing head defining a printing station and mounted on said frame for movement between printing and non-printing positions, pallet means, drive means and means for operatively connecting said pallet means to said drive means to effectuate substantially concomitant movement of said pallet means with said drive means, said improvement comprising,   means operatively connected with said drive means for indexing said pallet means with respect to said printing station,   means for effecting registration of said pallet means with said printing head after said pallet means have been indexed to said printing station,   said means connecting said pallet means to said drive means includes elastic resilient coupling means,   said resilient coupling means comprising at least one link interconnected between said pallet means and said drive means,   said link comprising a bearing housing connected to said pallet means and an elastic resilient bearing member, and   said resilient bearing member being disposed within said bearing housing and being connected to said drive means. .Iaddend. .Iadd. 19. A screen printing machine in accordance with claim 18, wherein   said pallet means includes a pair of opposed sides, and   said bearing housing is connected to one of the sides of said pallet means. .Iaddend..Iadd. 20. A screen printing machine in accordance with claim 18, wherein   said pallet means includes a pair of opposed sides,   said drive means includes a pair of opposed endless flexible drives, and   said resilient coupling means being disposed on the opposed sides of said pallet means and forming a connection with the respective endless drives whereby said flexible drives move said pallet means to and from said printing station when actuated. .Iaddend. .Iadd. 21. A screen printing machine in accordance with claim 20, wherein   said pallet means is positioned between said endless drives. .Iaddend. .Iadd. 22. A screen printing machine in accordance with claim 18, wherein   said registration means comprises locating means carried by said pallet means, and    a cooperating follower positioned on the  frame, and     means for activating said follower to cause the same to engage said locator means to effect registration of said pallet means with respect to said printing head. .Iaddend. .Iadd. 23. A screen printing machine in accordance with claim 22, wherein   said locator means comprises a locating notch of predetermined geometrical configuration, and   said cooperating follower is engageable within said locating notch. .Iaddend..Iadd. 24. A screen printing machine in accordance with claim 23, wherein   said locating notch is disposed on the underside of said pallet means. .Iaddend..Iadd. 25. A screen printing machine in accordance with claim 18, wherein   said resilient member is fabricated of a resilient material having a predetermined geometrical configuration, and   said resilient material has a plurality of apertures formed therein for increasing the resiliency of said member. .Iaddend.