GB2036679A - Conveyors - Google Patents

Abstract

A conveyor (1) has equidistantly spaced pivotally-mounted carriers (8, 8') each having its pivot point offset from its centre of gravity so that the carrier is gravity-biased to a first or component-receiving position from which it is tiltable, by a device (20, 18) to a second position for forwarding the component (24) to a next carrier. A loaded carrier is maintained in its second position by the weight of the component and in that position a stop surface (16, 16') of the carrier is raised to prevent forward movement of a component from a preceding carrier. The carrier is tilted by means of a cam 20 on a reciprocating shaft 22 which cam engages a follower 18 on the carrier. <IMAGE>

Description

SPECIFICATION Conveyors This invention relates to conveyors for transporting components and keeping them spaced from one another during the time they are on a conveyor even though the transport of a component from one station to the next on the conveyor should stop.

According to the present invention there is provided a conveyor having a loading end and a series of equidistantly spaced pivotally mounted carriers for transporting components forward from the loading end to an unloading end of the conveyor, each carrier having its pivot axis offset forwardly of its centre of gravity so that, when unloaded, it is gravity-biased to a first position from which it is tiltable by a device to a second position against the gravity bias, each carrier having an angled surface for cradling a component to be transported, said surface comprising a forward portion extending rearwardly of the pivot axis to a rear portion which, when the carrier is in its first position lies in a component-receiving position and the forward portion prevents forward movement of a component on the carrier, tilting of the carrier to the second position raises the rear portion and lowers the front portion so that it lies in a position in which a component at the intersection of the forward and rear portions, moves forward under its own weight on to the forward portion and, in said second position the rear of the rear surface portion is raised such that it prevents forward movement of a component behind said carrier on to said carrier's angled surface whereby components to be transported are kept separate from one another on the carriers and, the weight of a component on the forward portion of a carrier's angled surface is sufficient to overcome the gravity-bias of the carrier to its first position irrespective of the tilting action of the device.

Preferably the carriers are mounted in paired sets on the conveyor, each pair of a set being joined together by a heavy cross-shaft to ensure that the paired carriers will tilt under the influence of gravity.

Conveniently, the device for tilting the carriers comprises a series of wedge-shaped cams mounted on a reciprocable shaft, and each cam underlies a follower on a respective one of the cross-shafts joining paired carriers so that, upon movement of the reciprocable shaft in drive direction the cams engage the follower to tilt the carriers to the second position, and upon movement of the reciprocable shaft in the opposite direction (return) the followers can ride down the cam slopes so freeing the carriers for return to their gravity-biased first position.

The appended claims defined the scope of the monopoly claimed. How the invention can be performed is hereinafter particularly described with reference to the accompanying drawings, in which Figure 1 is a three-quarter view, from the loading end, of part of a conveyor according to the present invention; Figure 2 is a side view of part of the conveyor of Figure 1 with its drive mechanism; Figure 3 is an end view of a conveyor looking in the direction of the arrow 'A' in Figure 2; Figure 4 is a side view, to a larger scale, of one carrier of the conveyor in a forward position; Figure 5 is a view similar to Figure 4 but showing the carrier in a back position; and, Figure 6 is a plan view, also to a larger scale, of part of one side rail of a conveyor according to the invention, with a carrier secured thereto.

A conveyor 1, according to the present invention has frame members 2, supporting two horizontally spaced apart parallel side rails 4,4'. Equidistantly spaced stub shafts 6 secured on the inner face of side rail 4 face like stub shafts 6' on side rail 4', and each stub shaft has pivotally mounted thereon a carrier 8, 8' (conveniently of resilient hard wearing material e.g. urethane) spaced from the side rail by a spacer ring 9, 9'. Each pair of facing carriers 8, 8' constitutes one station of the conveyor. The carriers of each pair are connected at their rear ends by a heavy cross-shaft 10 which is positioned eccentric to the pivotal axis 11 of the carriers about their respective stub shafts, so as to provide an out-ofbalance force to bias the carriers into a back position (Figure 5).Each carrier has an angled upper surface comprising a long flat, or forward portion, 12,12' which merges into a short flat portion 14, 14' to the rear of the pivot axis of the carrier. This short flat portion is angled upwardly and terminates at a rear or stop face 16, 16' at the rear end of the carrier.

When a pair of carriers is in the back position the short flat portion of each carrier lies at a small angle, conveniently 5 , to the horizontal, as seen in Figure 5.

In this back position a cam follower 18 carried on the cross-shaft is in its lowest position and engages the lowermost end of a wedge-shaped cam 20 mounted on a reciprocable shaft 22. Movement of the shaft 22 from right to left, as seen in Figure 2, causes each cam to raise its respective follower against the weight bias and tilt the carrier into the forward position, shown in Figure 4. In this forward position the long flat portion 12, 12' lies at a small angle, suitably 5 , to the horizontal, and in this position the rear or stop face 16,16' of each carrier is raised above the long flat portion of the preceding carrier.

With the first pair of carriers of the conveyor in the back position, a component, for example an internal combustion engine crank shaft 24, placed on the short flat portions of the paired carriers at the first station will roll into the intersection 27, 27' of the short and long flat portions and will rest there until, upon the drive stroke of the shaft.22, that is from right to left as seen in Figure 2, the respective cam moves the follower and tilts the paired carriers into the forward position (Figure 4). As the paired carriers are tilted to the forward position so the component rolls down the long flat portion, until the component abuts the rear or stop face 16, 16' of the respective paired carriers ahead of it.Movement of the shaft 22 from left to right (the return stroke) allows the cam follower of the unloaded carriers to move down the slope of their respective cams and so permit the unloaded carriers to assume the back position, as shown in Figure 5. However, the weight of the component on the first pair of carriers is such as to hold them in the forward position, in which position the carriers rest against a stop 26, 26' on each rail 4, 4'. The component on the loaded carrier can now roll forward, because the slight slope of the long flat portion of each of the paired loaded carriers is in line with the short flat portion of the paired carriers ahead of it, and will come to rest on the intersection 27, 27' with the next long flat portion.At any station of the conveyor, when the carriers at that station are loaded the weight of the component will keep the carriers in the forward position irrespective of the position of the cam which acts on the follower associated with that pair of carriers.

Thus, until the component at a station of the conveyor is either unloaded or moved onto the next station forward of it no following component can move on to that station. The components are thus kept spaced from one another and cannot pile up against one another should the conveyor stop for any reason.

Where the conveyor is to be used for the transporting of identical components a suitable value for the weight of the cross-shaft 10 can be determined to ensure that the paired carriers will be correctly biased to return to the back position when unloaded.

The carriers need not have an angled upper surface formed by two flat portions as described above. The upper surface could be curved, provided it had a trough-like configuration such that a component of work piece could be cradled therein.

Claims (4)

1. A conveyor having a loading end and a series of equidistantly spaced pivotally mounted carriers for transporting components forward from the loading end to an unloading end of the conveyor, each carrier having its pivot axis offset forwardly of its centre of gravity so that, when unloaded, it is gravity-biased to a first position from which it is tiltable by a device to a second position against the gravity-bias, each carrier having an angled surface for cradling a component to be transported, said surface comprising a forward portion extending rearwardly of the pivot axis to a rear portion which, when the carrier is in its first position lies in a component-receiving position and the forward portion prevents forward movement of a component on the carrier, tilting of the carrier to the second position raises the rear portion and lowers the front portion so that it lies in a position in which a component at the intersection of the forward and rear portions moves forward under its own weight on to the forward portion and, in said second position the rear of the rear surface portion is raised such that it prevents forward movement of a component behind said carrier on to said carrier's angled surface whereby components to be transported are kept separate from one another on the carriers and, the weight of a component on the forward portion of a carrier's angled surface is sufficient to overcome the gravity-bias of the carrier to its first position irrespective of the tilting action of the device.

2. A conveyor according to claim 1, in which the carriers are mounted in paired sets on the conveyor and each pair of a set is joined together by a heavy cross-shaft located eccentric to the pivot axis of the carriers to ensure that the paired carriers will tile underthe influence of gravity.

3. A conveyor according to claim 2 in which each cross-shaft has a cam follower thereon engageable by a respective one of a series of wedge-shaped cams mounted on a reciprocable shaft so that upon movement of the reciprocable shaft in a drive direction to cams engage the followers to tilt the carriers to the second position, and upon movement of the reciprocable shaft in the opposite direction the followers can ride down the cam slopes in freeing the carriers for return to their gravity-biased first position.

4. A conveyor substantially as hereinbefore particularly described with reference to and as shown in the accompanying drawings.