GB1561965A - Apparatus for conveying flat items - Google Patents

Description

(54) IMPROVEMENTS IN APPARATUS FOR CONVEYING FLAT ITEMS (71) We, THE POST OFFICE, a British Corporation established by Statute, of 23 Howland Street, London, WIP 6HQ, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : This invention relates to-apparatus for conveying substantially flat items, for example, documents, letters, and postcards.

The invention is concerned particularly with a transport mechanism which is suitable for use in apparatus for producing from a stack of flat items a stream thereof having a rate and spacing which can be synchronised with the rate of operation of subsequent item handling machinery.

In high-throughput handling of flat items, it is known practice both to feed items individually on specific command from an operator and to feed items automatically using high speed automatic equipment; in both cases the practices have resulted in a stream of items issuing in random fashion.

In order that these items can be processed by subsequent automatic handling machinery, for example, an item diverting machine or an item stacking unit, either the rate at which letters arrive at the machinery or the speed of operation of the machinery itself must be adjusted to obtain synchronism between letter arrival and machine operation.

Synchronism has in the past been obtained using, for example, photodetector devices set to monitor the arrival of successive items, the photodetector devices controlling timing means which delay or speed-up the letter arrivals and control machine operation to achieve synchronism.

According to the invention there is provided apparatus for handling flat items, including a perforated conveyor belt; means operable to produce, through the perforations, a suction effect at one surface of the belt for holding an item against the belt, and a device for receiving flat items successively from the belt, the suction-producing means being operable intermittently at a rate dependent on the rate at which items are handled by the device.

The conveyor belt may have a smoothsurfaced portion and an adjacent marginal portion which is in non-slip engagement with a drive pulley, the smooth-surfaced portion being arranged for rotation about a system of smooth-surfaced rollers.

The maginal portion and the drive pulley may be formed with interengageable teeth to provide the non-slip engagement therebetween.

One of the roller may be mounted coaxially with the drive pulley to idle relative thereto. At least one other roller may have an end portion formed with teeth engageable with those of the strip portion of the belt.

The apparatus may include pick-up means operable - to present flat items successively to the said one surface of the belt.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a letter transport mechanism; Figure 2 is a plan view of letter handling apparatus incorporating the letter transport mechanism of Fig. 1; Fig. 3 illustrates a modified form of part of Fig. 2, and Figure 4 is plan view a modified component of Fig. 2.

Referring to the drawings in detail, Figure 1 shows a letter transport mechanism 1 including a conveyor belt 2.

The belt 2 extends around a pair of rollers 3 and 4, the roller 3 being mounted coaxially with and adjacent a drive pulley 5 which has teeth 6 formed at its circumference and engages a marginal strip portion 7 of the belt 2 having co-operating teeth 8 formed on its inner surface.

Interengagement between the teeth 6 and 8 ensures a non-slip drive transfer from the pulley 5 to the belt 2. The pulley 5 is driven through a shaft 9 by a drive mechanism (not shown) having a variable speed adjustment facility for setting the belt speed.

The rollers 3 and 4 which are mounted to idle about respective shafts 9 and 10 have smooth surfaces which are engaged by a smooth surfaced body portion 11 of the belt 2. The roller 4 also has a toothed end section for supporting the toothed strip portion 7. To avoid tracking problems, the belt portions 7 and 11 are of the same pitch circumferential length" that is, the system comprising the smooth rollers 3, 4 and smooth belt oprtion 11 is the effective equivalent of the system comprising the toothed pulleys 5, 10 and the toothed belt portion 7.

Spaced along the length of the body portion 11 are perforations 13.

In the apparatus shown in Figure 2, the inner surface of the body portion 11 lies closely adjacent a suction box 14 which can communicate under the control of a valve 24 with a source of suction S. When the suction box 14 is connected to the source S it will produce, at the belt 2, a suction effect which extends through the perforations 13 to the outer surface of the body portion 11 and which is used, as will be described below, to transport letters to a stacker box 26.

In operation of the apparatus, letters are presented successively to the outer surface of the body portion 11 by a pick-up mechanism 15 which is of the double bellows type shown in our Patent Specification No.

1,429.483 and is described briefly below.

When a suction effect is present at the outer surface of the body portion 11, a letter presented by the mechanism 15 is sucked towards the body portion and is then carried away by the transport mechanism 1 to the stacker box 26. The production of the suction effect at the outer surface of the body portion 11 is intermittent, being dependent on operation of the valve 24 which, in turn, is actuated intermittently via a mechanical link 25 by the stack box 26.

The stacker box 26 includes a pair of stacker box cams 27 which push a previously formed stack 28 of letters away to permit an incoming letter 29 from the transport mechanism 1 to enter between the stack 28 and the stack box wall with adequate clearance. The cams rotate to the broken line position as each letter is injected into the box 26. The mechanical link 25 between the stacker box cams 27 and the valve 24 includes a secondary cam 30 rotatable with one of the stacker box cams 27. The secondary cam pivots a lever 31 to open or close a flap 32 of the valve 24 to establish or prevent respectively fluid communication between the source or suction S and the suction box 14.

The pick-up mechanism 15 which presents letters to the transport mechanism 1 comprises a first flexible bellows 16 connected between a source of suction S and one end of a hallow arm 17 pivoted at 18, and a second flexible bellows 19 connected between the other end of the hollow arm 17 and an apertured pick-up foot 20. The arm 17 is dimensioned so that on pivoting in the direction of the arrow 21, the foot 20 is brought against the top letter of a letter stack 22. On establishment of suction inside the mechanism 15 the top letter seals against the apertured pick-up foot 20, and a vacuum build-up occurring inside the bellows 16, 19 and the arm 17 causes both the bellows to contract to pivot the arm 17 and to transfer the letter to a presentation position. From this position, the letter is sucked towards the body portion 11 of the belt 2 as soon as the valve 24 is operated, via the link 25, to establisth communication between the source S and the suction box 14.

The belt movement then bears the letter away from the influence of the pick-up mechanism 15 and it is delivered to the stacker box 26. On removal of the letter from the foot 20, the change of pressure inside the pick-up mechanism 15 causes the bellows 16 and 19 to expand' and to drive the foot 20 against the top of the stack to commence the next pick-up cycle. The next letter is picked up and presented for transport, but feeding of this letter is inhibited because operation of the stacker box 26 will have moved the flap 32 of valve 24 to cut-off communication between the source S and the suction box 14. The letter accordingly remains on the foot 20 of the pick-up mechanism 15 until the valve 24 is next operated to re-establish communication between the source S and the suction box 14.

As a result, the rate at which letters proceed from the transport mechanism 1 is determined by the rate at which they are handled by the stacker box.

As a modification of the arrangement shown in Fig. 2, the mechanical synchronisation between the stacker box 26 and the transport mechanism 1 can be replaced by electrical synchronisation obtained using a pulse generator, triggered by rotation of the stacker box cams, to control a solenoid for operating the valve 24.

If desired. the control exerted by the stacker box cams 27 on the stack 28 can be extended by shaping the cams as illustrated in Fig. 3 (showing the letter stacker only) so that the second cam 27b (relative to an incoming letter 29) remains in contact with the stack face for longer than the first cam 27a.

Figure 4 is a plan view of a simplified- form of the pick-up mechanism 15 which may be used in the apparatus shown in Fig.

2. The reference numerals used in Fig. 4 correspond to those used in Fig. 2 and it will be seen that the amplification resides in the elimination of the bends in the hollow arm 17, resulting in the two bellows 16 and 19 being aligned with each other.

Claims (7)

WHAT WE CLAIM IS : -

1. Apparatus for handling flat items, including a perforated conveyor belt; means operable to produce, through the perforations, a suction effect at one surface of the belt for holding an item against the belt, and a device for receiving flat items successively from the belt, the suction-producing means being operable intermittently at a rate dependent on the rate at which items are handled by the device.

2. Apparatus as claimed in claim 1, in which the conveyor belt has a smoothsurfaced portion and an adjacent marginal portion which is in non-slip engagement with a drive pulley, the smooth-surfaced portion being arranged for rotation about a system of smooth-surfaced rollers.

3. Apparatus as claimed in claim 2, in which the marginal portion and the drive pulley are formed with interengageable teeth, providing the non-slip engagement therebetween.

4. Apparatus as claimed in claim 2 or claim 3, in which one of the rollers is mounted coaxially with the drive pulley to idle relative thereto.

5. Apparatus as claimed in claim 4, when appendant to claim 3, in which at least one other roller has an end portion formed with teeth engageable with those of the strip portion of the belt.

6. Apparatus as claimed in claim 5, including pick-up means operable to present flat items successively to the said one surface of the belt.

7. Apparatus for handling flat items, substantially as described herein with reference to, and as shown in, Fig. 2 of the accompanying drawings; or Fig. 2 as modified by Fig. 3 or Fig. 4.