GB2096088A - Interrupting the drive to rollerways - Google Patents

Abstract

A conveyor comprising a plurality of load-carrying rollers 1 and normally driven through a common element 5 comprises means for automatically displacing the rollers away from the driving element and reducing the driving force applied to the rollers in the event of obstruction to the conveyance of articles thereon and means for positively displacing the driving element away from the rollers to remove the said driving force. If the driving element is a belt, the first named means is adapted for moving the rollers away from the said belt and the second-named means for lowering the belt out of driving engagement with the rollers. The movement of the rollers away from the belt may be produced by rolling of trunnions 2 thereof up inclined surfaces 3a. The movement of the belt out of driving engagement with the rollers may be produced by lowering pressure rollers 6 disposed normally to hold up a flight of the belt in contact with the load-carrying rollers. <IMAGE>

Description

SPECIFICATION Improvements relating to conveyors This invention concerns improvements relating to conveyors, particularly so-called accumulating conveyors. With such conveyors, it is known to provide means whereby the building up of so-called line pressure, when articles on the conveyor are obstructed deliberately or by accent, is limited to a minimal value.

fhe present invention seeks to provide an improved conveyor, of the kind comprising a number of load-carrying rollers normally driven through a common driving element such as a belt, whereby-numbers of articles, such as cartons or other packages, can be accumulated on the conveyor or a section thereof under minimal line pressure up to a predetermined length, whereafter the so-called "slug" of articles can be brought under zero line pressure by removing the drive from the said rollers.

According to the invention, a roller conveyor of the aforesaid kind comprises means for automatically displacing load-carrying rollers away from the driving element and reducing the driving force applied to those rollers in the event of obstruction to the conveyance of articles thereon and means for positively displacing the driving element away from the said rollers to remove the said driving force.

The first-named means preferably comprises means causing the said rollers to be moved in the direction away from a driving-belt element and the second-named means preferably comprises means for lowering the said belt element out of driving engagement with the said rollers.

Such a conveyor may be so activated under the control of electric sensors by means of electro-pneumatic valves and pneumatic cylinders as to permit the accumulation of "slugs" of articles along respective modular lengths of conveyor and to cause the release thereof either as separate slugs in required sequence or to empty the whole conveyor in one com plete slug length.

Use may be made of pneumatic sensing means detecting the presence of articles over a modular length of conveyor and operative to transmit a pilot air signal to a pneumatic valve which causes a pneumatic cylinder to bring the modular section of the conveyor into a state of zero line-pressure accumulation.

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side view of a portion of an accumulating conveyor, Figure 2 an end view of one side of the conveyor, Figure 3 a section to a larger scale on the line A-A in Fig. 1, and Figure 4 a detail at right angles to Fig. 3, The package conveyor illustrated comprises load-carrying rollers 1 (Fig. 1) supported at each end by trunnions 2 resting in wide vertical slots 3 in longitudinal side-frame members 4 of outwardly open channel section (Fig. 4). The effective bottoms 3a (Fig. 1) of the slots 3 are inclined downwardly in the direction of package travel P.

Driving means for the rollers 1 comprises an endless driving belt 5 which is normally continuously driven and whose upper flight 5a moving in the direction B is supported at intervals on pressure rollers 6 which, in the normal driving mode for the conveyor, hold up the said upper flight to maintain driving contact between it and the load-carrying rollers 1. When the packages resting on the rollers 1 are moving freely along the sequence of rollers 1 in the direction P, the trunnions 2 of the rollers 1 will be positioned at the lower, right-hand, ends of the bottoms 3a of the slots 3.If the packages are obstructed obsuced in the course of their movement on the load-carrying rollers 1, for example by encounter with a manually or automatically controlled stop introduced into their path or by hindrance due to an accidental cause, the driving force which continues to be trnnsmitted by the belt 5 to the rollers 1 will cause the trunnions 2 to roll up the inclined slot bottoms 3a so that the said rollers are lifted up in relation to belt flight 5a and that the driving influence of the latter is reduced. In this manner, the line pressure on the leading arrested package can be reduced to, say, 5% of the load being carried on the conveyor or on a relevant section or modular length thereof.

To enable the line pressure to be further reduced to zero, the following means is provided: The trunnions 6a (Fig. 3), provided with bushes 7, of a group of pressure rollers 6 are located in narrow slots 8, inclined downwardly in the same direction P as the bottoms 3a of the slots 3, in the frame members 4. Inside the members 4 and between the bushes 7 and the adjacent ends of the pressure rollers 6 there is a link 9 cou piing the rollers 6 of the said group. Suitably and as shown, the link 9 is a flat bar provided with round holes 9a (Fig. 3) through which the trunnions 6a of respective rollers 6 pass.

A link 9 similarly arranged on the other side of the conveyor receives the trunnions at other ends of the rollers 6.

A two-armed lever 10 is fast on a shaft 11 which is pivotably mounted in the adjacent frame member 4 (Fig. 2; and in the similar frame member on the other side of the conveyor. The upper arm of the lever has a pinand-slot connection at 1 Oa to the link 9, while the lower arm is pivotally connected at 1 Ob to the piston 1 2 of a single-acting pneumatic cylinder 13, with air inlet 1 3a, which is pivotably connected at 1 3b to a bracket 14 bolted to the adjacent frame member 4.A tension return spring 15 (Fig. 13 anchored to the frame member 4, conveniently at a slot 3, and operatively connected to the link 9, suitably adjacent to a bushed trunnion 6a of a roller 6, constantly urges the link 9 in the direction B of movement of the driving belt flight 5a, that is towards the position in which the trunnions 6a of the pressure rollers 6 are at the higher ends of the slots 8 and the said rollers hold up the belt-flight 5a in driving contact with the load-carrying rollers 1 (Fig.

1). On horizontal movement of the link 9 in the direction opposite to the direction B, imparted through the lever 10 by pneumatic actuation of the piston 1 2 in the direction C, the bushed trunnions 6a will be moved down the slots 8 so that the belt-flight 5a is relieved from the pressure of the rollers 6. The load carrying rollers 1 cease to be driven and come to rest.

With a single-acting cylinder and spring return, operation of the cylinder may be contolled by way of a three-port solenoid-actuated air valve. Build-up of articles along the load carrying rollers 1 of a conveyor or a modular length thereof may be detected by means of a photo-electric sensor (not shown).

The sensor is so designed that when the beam of the sensor has been interrupted for a preset time period, determined by the time required for the passing of an article of normal length, a signal is passed to the aforesaid air valve which causes air to be admitted to the cylinder 1 3. The resultant piston movement causes the link 9 to be shifted to release the rollers 1 concerned from the driving action of the belt flight 5a, leaving the articles on the said rollers in zero line-pressure accumulation.

If required, a series of such sensors and pneumatic cylinders may be employed to control a number of groups of rollers constituting modular sections of a complete conveyor.

When articles accumulated on a section or sections of a conveyor require to be moved, electrical signals may be transmitted, manually or under automatic control, to reverse the operation of the solenoid valves and pneumatic cylinders to restore the drive to the loadcarrying rollers 1.

Double-acting pneumatic cylinders controlled by way of five port solenoid valves may alternatively be employed. However, the use of single-acting cylinders, with spring return as described above, has the advantage that the conveyor will, in the event of failure in the supply of air to the cylinder or cylinders, be returned to a driven condition, but with minimal, not full, line pressure until obstruction to the accumulated articles has been removed.

Claims (6)

1. A roller conveyor comprising a plurality of load-carrying rollers arranged normally to be driven through a common driving element, means for automatically displacing the said rollers away from the driving element and reducing the driving force applied to the rollers in the event of obstruction to the conveyance of articles thereon and means for positively displacing the driving element away from the rollers to remove the said driving force.

2. A conveyor according to claim 1, wherein the driving element is a driving-belt, the first-named means being adapted for moving the rollers away from the said belt and the second-named means for lowering the belt out of driving engagement with the said rollers.

3. A conveyor according to claim 2, wherein the movement of the rollers away from the belt in the event of obstruction to conveyance is arranged to be produced automatically by rolling of trunnions thereof up inclined surfaces.

4. A conveyor according to claim 2 or 3, wherein the movement of the belt out of driving engagement with the rollers is arranged to be produced by lowering pressure rollers disposed normally to hold up a flight of the said belt in contact with the load-carrying rollers.

5. A conveyor according to claim 4, wherein the lowering of the belt is effected by pneumatic means which are operatively connected to longitudinally movable bars having inclined slots in which trunnions of the pressure rollers are engaged.

6. A conveyor substantially as hereinbefore described with reference to the accompanying drawings.