Patent GB-711840-A (GB)
Title: Improvements in or relating to apparatus for marshalling flat articles
Inventor: COPPING GEOFFREY PERCY
IPC: B07C1/02
Filed: 1950-06-30
Abstract: 711,840. Feeding devices. POSTMASTER GENERAL. July 19, 1951 [June 30, 1950], No. 16462/50. Class 117 [Also in Groups XXX, XXXV, XXXVII and XL (b)] A heap of flat articles, such as postal letters and packets, is converted into :a stream of articles moving at high speed in single file, running on their long edges and separated from each other by certain predetermined minimum distances. The articles are depostited in an irregular heap on an endless conveyer belt, Fig. 1, from which a controlled quantity is delivered to means C which convey them on edge to a device D which divides the stream into two or more subsidiary streams, the articles in each of which are separated from each other by substantially equal distances.Means for regulating the speed of the belt 1, ,and thus the rate of feeding the articles to the shoot 3, is disposed near the end of the belt. This rnaams measures the cross-sectional area of the letter stream and comprises a series of rollers 4, Fig. 2, which are carried by spring-loaded pivoted members 5 and support followers 6a carried by verticallymovable toothed racks 6. These racks omgage. pinions 7 on the spindles 8 of a series of variable measuring condensers, the variation in the capacitance of which as the rollers rise or fall is used to control the voltage applied to an amplifier. The amplified voltage, after rectification and single stage D.C. amplication, is applied to the field winding of a generator, the output of which is applied to the armature of an electric motor, with its field energised from an external source, which drives the conveyer. The articles pass from the belt through take-off rollers 2 to the shoot 3 which directs them edge on to a narrow conveyer belt 18. Side walls 21 maintain them in the erect poisition. The articles pass from this belt on to a belt 19 which travels at a much higher speed and is inclined upwtards. The jerk imparted to the 'articles at fthe moment of transfer causes many of them to be turned through a right angle to come to rest on their longer edges. The articles pass from the belt 19 on to the belt 20 which moves at the same speed as the belt 18 and delivers them to the space between two co-operating endless belts 26, Fig. 6, disposed on edge. The articles pass between rollers 23, which rotate about vertical axes and also oscillate as a pair about a vertical axis 24, to a diverter 25 which separates them into two streams. Similar devices 23a, 25a effect the further subdivision of each stream. Each stream then passes to a channel 28, Fig. 1, comprising a series of smooth-faced rollers 31 and smooth-faced walls 29, 29a, Fig. 9. The remote ends of the channels are disposed in echelon and are closed by plates 30. A slot 35 is provided in each wall 29a near the plate 30 of sufficient size to receive the suction head 34 of a tubular suction arm which moves in the path shown in broken lines in Fig. 13 and delivers the articles singly to rollers 36. These rollers deliver the articles to a shoot 37 down which they pass to a conveyer belt 39 between; side walls 38, 38a. On this belt any articles which are still in pairs are separated and any which are resting on their short edges are turned through a right angle. As the articles pass along the channel 41, they are halted by a reciprocating member 40 which moves in synchronism with the suction head 34 in such a manner that when the member 40 is withdrawn from the channel to release the articles, there is a regular interval between the leading edges of the successive articles which have passed the stop member. The articles pass next between a suction head 46, Fig. 14, and a reciprocating hammer head 44. If the articles are in pairs, the one nearer the suction head is driven into contact with it and retained momentarily by the blow imparted by the hammer to the other article. This latter article moves forward as the hammer is retracted and is diverted into the parallel channel 42 by an oscillating pivoted blade 48 which is returned to its non-obstrustive position in time to allow the passage of the other article when released from the suction head 46. The channel 42 delivers the articles to a box for return to the belt 1. Some of the articles left in the channel 41, which are now arranged as single accurately spaced items, may be resting upon their short edges and in order to effect their rotation to the correct position, they are passed between a pair of blunt-ended smooth-faced claws or pincers 50, Figs. 15, 16, which is operated by a series of photo-electric cells 52 .. 55 arranged at different heights above the conveyer belt 59 and the distance of each of which from a master photoelectric cell 56 is the same as its height above the belt. The claws &c. wthen actuated grip any letter stainding on a short edge between its centre and top edge and retard its movement, so that it turns about the rear lower corner. This reorientation of some of the letters will alter their spacing. This defect is corrected by passing the stream through a monitoring section, Fig. 17, having a reciprocating pin 60 which is controlled by a photo-electric cell and light source assembly 62. This pin moves across the channel 51 to halt the letters as soon as the rear end of the last halted letter clears the light beam of the device 62. The pin is withdrawn at regular intervals. The four separate streams are next carried by endless belts 59 towards an endless belt 63 arranged obliqualy across their ends. This belt is pressed against plates 65 by fixed pressure rollers 66. The plates 65 have curved extensions 65a which co-operate with short transfer belts 67. The stream is then formed into a high-speed stream of accurately spaced letters by passing it between rollers 69, the peripheral speed of which is about four times that of the stream. This result can, however, be obtained by accelerating the letters in each stream to the desired final speed prior to feeding them to a common conveyer. In a modification the device D, Figs. 1, 6, is replaced by an arrangement in which the main stream is split and diverted into any one of a series of channels 72, Fig. 19, by pivoted blades 71 controlled by photo-electric devices and light assemblies 70, 70a. Each channel is closed by a plate 73 and a pneumatic extractor device 74 is disposed near to it. The devices 70 are placed at a distance of approximately one and a half times the length of an average letter from the plates 73. The devices 70a control the blades 71, but will operate only if the light beam of the corresponding assembly 70 is broken at the same time. When all the channels 72 are full, the stream will pass all the diverting points and be returned by a by-passing conveyer to the receiving end of the main stream. In another modifiication the device shown in Figs. 15, 16 is replaced by a series of pairs at oppositely rotating brushes disposed at progressively higher levels and driven at a peripheral speed which is less than the speed of the belt upon which the letters rest.