Enveloping device
BACKGROUND OF THE INVENTION 
     This invention concerns an enveloping device with a container for empty envelopes, and a process for operating this enveloping device. 
     In prior art enveloping machines the envelope is withdrawn from a stack, brought into position, opened and the content is then inserted, leading to a pause which delays the packing rate. In this prior art machine, various elements carry out to and fro movements and this restricts the packing rate of this prior art enveloping machine. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of this invention to avoid the disadvantages of the state of the art and to provide an enveloping device with which the packing rate can be approximately doubled. This is achieved according to the invention by the features described in this application. A further object is to design the enveloping machine in such a way that even at high packing rates, the envelopes can be suitably deformed to some degree, i.e. opened, whilst they are being conveyed from the envelope stack to the packing trap and before they reach the latter, so that the envelopes can be reliably maneuvered onto the packing trap. This is achieved by means of a holding down roller disposed in the area above the end of the packing trap closest to the envelope container. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An example of an embodiment of the invention will be described below in more detail with reference to the accompanying drawings, wherein: 
     FIG. 1 is a side schematic elevational view of the enveloping device of this invention; 
     FIG. 2 is an enlarged schematic side elevational view of the drive for the opener claw of the device of FIG. 1; 
     FIG. 3 is a schematic cross-sectional view taken along the line III--III of FIG. 2; 
     FIG. 4 is an enlarged view of a part of FIG. 1 showing the transport of an envelope in the direction of the packing trap; 
     FIG. 5 is a view similar to FIG. 4 which shows how an envelope is drawn onto the packing trap; 
     FIG. 6 is a view similar to FIG. 4 which shows how the envelope content is inserted into the packing trap; 
     FIG. 7 is a view similar to FIG. 4 which shows how the packed envelope is removed; and 
     FIG. 8 is a perspective view of the packing trap. 
    
    
     DETAILED DESCRIPTION 
     The basic construction and the operating sequence of the process of the enveloping device for an enveloping machine will be described with reference to FIG. 1. The enveloping device or unit forms the central part of an enveloping machine. Pre-treatment of the contents of the envelope, i.e. of the sheets of paper, or rolls or stacks of pre-printed forms, brochures etc., in the form of cutting, grouping, folding etc., and, likewise, post-treatment of the packed envelopes in the form of closing, sealing, franking, bundling etc., do not take place within the scope of the enveloping device described here. 
     From a vertical stack 1 of empty, unsealed envelopes arranged with their bent-over flap downwards, the flap 2 of the bottom envelope 3 is opened with one of three opener claws 5, 6 or 7 disposed on a shaft 4. As soon as the flap 2 is sufficiently open, it is seized by two conveyor elements 8, 9 and pressed against two conveyor rollers 10, 11 The conveyor elements 8, 9 and the conveyor rollers 10, 11 have the same peripheral speed. The opener claws 5, 6 and 7 and the conveyor elements 8 and 9 are disposed on the same shaft 4, but are supported and driven independently of each other. In order to prevent the opener claws 5, 6 and 7 from damaging the envelope at high processing speeds, i.e. by perforating the flap, the opener claws 5, 6 and 7 rotate in a whole number ratio slower than conveyor elements 8 and 9. Opener claws 5, 6 and 7 are disposed at regular intervals on the periphery. The number of opener claws and therefore the rotation ratio of opener claws and conveyor elements is dependent on the envelopes used. The opener claws are only operated from a coupling 12 when a packing operation is to be carried out. The conveyor elements 8, 9 and the conveyor rollers 10, 11 run continuously. 
     While the opened envelope is conveyed onwards towards a packing trap 13, hold down elements 14 and 15 ensure that the envelope is fed along a guide plate 16. Two further pairs of transport rollers 17, 18 and 19, 20 ensure that the envelope is reliably conveyed. As soon as the envelope has been conveyed so far that its flap is positioned under a hold down roller 21, the latter begins to descend. Simultaneously, the packing trap 13 begins to pivot around a point of rotation 22 towards the envelope. The linear movement of the hold down roller 21 and the pivotal movement of the packing trap 13 are controlled by a cam 23 and the motion thereof is transferred to the hold down roller and the packing trap by means of a cam follower 25 and a system of levers 24, 26, 27, 28, 29. As soon as the packing trap has reached the uppermost position and the envelope opening has been drawn over the trap, conveyor rollers 30 begin to convey the envelope into the final position on the packing trap 13 (see also FIG. 5). As soon as this position has been reached, the packing trap 13 pivots downwards and the holding down roller 21 is pushed upwards. While the envelope is being pushed onto the packing trap 13, from the opposite side, conveyed by transport fingers 34 affixed to a toothed belt 33 guided over rollers 31 and 32, the prepared content 38 of the envelope is conveyed into the packing trap on a feed plate 60 (see also FIG. 6). On the upper side of the packing trap there are projections 35 and 36, so that the transport fingers 34 do not get blocked by the envelope flap 2. The end 37 of the packing trap closest to the envelope contents brought up to it is funnel-shaped. The transport fingers 34 serve to push the contents 38 together with the envelope 3 to conveyor belts 43 and 44 guided on rollers 39, 40, 41 and 42. The conveyor belts 43 and 44 convey the envelope and its contents to another processing point of the enveloping machine (see also FIG. 7). There is never any pause in the movement of the contents 38 of the envelope; they are pushed at a constant rate through the packing trap 13 into the envelope 3 and, together with the latter, between the conveyor belts 43 and 44. As soon as the envelope 3 has reached the conveyor rollers 45 it is gripped between the latter and the lower conveyor belt 43 and transported by the conveyor belts 43 and 44 out of the enveloping unit, where it may be finished for dispatch by other units. The conveyor rollers 20 are non-rotatably connected with the toothed belt driven shaft 46, and the conveyor rollers 45 are supported on the same shaft with ball bearings. The next envelope is withdrawn from stack 1 at the moment when the previous packed envelope begins to be drawn off from packing trap 13. The flaps of the two envelopes cross each other in the area beneath hold down roller 21. The entire enveloping unit is driven by a motor 47 which can be continuously adjusted by a frequency converter. All the moveable parts of the unit are driven by this motor, thus ensuring that all movements are synchronous to each other, this being necessary for disruption-free operation. 
     FIG. 2 shows a side view of the drive for the opener claws 5, 6 and 7. 
     FIG. 3 shows a section along line III--III of FIG. 2. The drive from motor 47 is transferred via a toothed belt 48 to a toothed wheel 49 which is non-rotatably connected with the shaft 4. Shaft 4 is supported and held axially in side plates 50 and 51. The conveyor elements 8 and 9 are non-rotatably connected with shaft 4. Via a further toothed wheel 52 which is non-rotatably connected with shaft 4, a toothed belt 53 and a toothed wheel 55 non-rotatably connected with a second shaft 54, the drive for the opener claws 5, 6 and 7 is brought about via a coupling 12. A toothed wheel 56 is non-rotatably connected with shaft 54 and drives another toothed wheel 58 connected with the opener claws 5, 6 and 7, via a toothed belt 57. The toothed wheel 58 and the opener claws 5, 6 and 7 are rotatably supported on shaft 4 with ball bearings. Toothed wheels 56 and 58 form a stepdown gearing, so that the opener claws rotate slower than the conveyor elements 8 and 9. Shaft 54 is also supported and axially held in the side plates 50 and 51. 
     FIG. 4 is a schematic of the enveloping device, in particular the area of the packing trap. The position of the envelope 3 is as shown in FIG. 4 with its flap below the hold down roller 21. The end of the flap abuts the front portion 61 of the packing trap 13. 
     FIG. 5 shows the same section of the enveloping device as in FIG. 4. The hold down roller 21 has descended and the packing trap 13 has been pivoted around its point of rotation 22 and upwards with its front portion 61 towards the hold down roller 21. The envelope is thereby deformed and opened and can be pushed over the packing trap 13. The conveyor rollers 30 convey the envelope into its final position on the packing trap 13. 
     FIG. 6 shows the same part of the enveloping device as FIGS. 4 and 5. In FIG. 6, the envelope is shown in its final position on the packing trap 13. The packing trap is pivoted downwards around the point of rotation 22 and the hold down roller 21 is pushed upwards. While the envelope is pushed onto the packing trap, the contents 38 of the envelope are conveyed by the transport fingers 34 into the packing trap. Two parallel toothed belts 33 with transport fingers 34 attached thereto are provided. 
     FIG. 7 shows the same part of the packing device as FIG. 6. The contents 38 are pushed out of the packing trap by the transport fingers 34 together with the envelope. The envelope is conveyed over a transfer plate 59 by the conveyor rollers 45 to the conveyor belts 43 and 44 and is then transported out of the enveloping unit, where the envelope is finished for dispatch by other units. 
     FIG. 8 shows a perspective view from below of the packing trap. It has two bent over edges 62 and 63, between which the contents are pushed. The end 61 of the packing trap closest to the stack of envelopes is also bent. The opposite end 37 is funnel-shaped for optimal reception of the contents of the envelope. Two slots 64 and 65 are provided, through which the transport fingers 34 can protrude. The projections 35 and 36 serve to lift slightly the envelope pushed over the flap so that the transport fingers do not get blocked by the flap. 
     The enveloping device has only very few translationally moving or oscillating parts in order to keep at a minimum the thereby occurring forces of inertia. With the exception of the hold down roller 21, the packing trap 13 and the lever system acting on the latter, only rotational movements occur. In the holding down roller and the packing trap only small displacements or pivot angles occur. 
     The enveloping device according to the invention permits up to 26,000 packing operations per hour, which corresponds to a doubling of the capacity of the prior art enveloping machines.