ALIGNING AND SPACING ARTICLES

Abstract: The stops (16,18) can each occupy a raised position in which the tins (24,26) approaching the relevant stops are prevented from moving with a conveyor (10), by abutment with those stops, or a lowered position in which the tins can pass the stops. The tins (24,26,28) approach the stops (16,28) at different angles and spacings. The stops (18) determine the minimum gaps between the tins leaving the arrangement, and the stops (16) align those tins such that their longitudinal axis extends perpendicularly to the reflection of travel of the conveyor. If a tin is not correctly aligned when it approachs the stops (16), the forward edge of the tin abuts the stops (16) when in the raised position, and the stops (16) are, after a short duration, then moved to the lowered position to allow time for the forward edge of the tin to settle against the stops (16) and be correctly aligned.

Description: The present invention relates to a method of and apparatus for aligning and spacing articles on a conveyor. The invention is particularly, although not exclusively applicable to the alignment and spacing of pans or tins containing farinaceous material. In a bakery, the pans or tins may lie on the conveyor at angles and may abut each other. The pans may touch each other and come off or jam the conveyor as the conveyor travels around bends, thus necessitating shut down of the line until the blockage is cleared, with loss of production time and possible loss of at least part of the production run. It has previously been proposed to check the spacing between adjacent pans by means of a photo electric beam and to give an alarm if the spacing is below a predetermined value. However, as the spacing and the alarm are related to the time which the photo electric beam detects a gap, no account is taken of the greater gap which may be present if the conveyor is moving at a faster speed, and an alarm may thus be given even if the spacing is sufficient because the beam only detects a gap for a short period of time. Furthermore, no provision is made for the straightening out of the pans, which may be oblong, so that their longer axis extends perpendicularly to the direction of travel. This orientation of the pans is the most favourable as it permits the gap between pans to be less than if the pans are at another angle on the conveyor whilst avoiding fouling of successive pans as they subsequently pass around the bends of the conveyor. There is shown in G.B. Patent Publication No. A-2112728 a method of spacing a succession of articles along a conveyor comprising using stop means movable between a first position in which articles approaching the stop means along the conveyor are prevented from passing the stop means and a second position in which articles are able to pass the stop means. According to one aspect of the present invention, a method of spacing a succession of articles along a conveyor comprising using stop means movable between a first position in which articles approaching the stop means along the conveyor are prevented from passing the stop means and a second position in which articles are able to pass the stop means is characterised in that the method further comprises correctly aligning articles if the articles are not correctly aligned on the conveyor with respect to the direction of travel of the conveyor by the sequence of placing the stop means in the first position, turning an article which abuts the stop means into a correct alignment position by movement of the conveyor, the article thereby fully settling against the stop means, and moving the stop means to the second position after an article has abutted the stop means and after the article has become correctly aligned and then returning the stop means to the first position once an article is clear of the stop means. The method may comprise always moving the stop means to the second position after an article has abutted the stop means. The method may further comprise using the movement of the stop means from the first position to the second position to control the spacing between successive articles. The method may further comprise detecting when an article is correctly aligned on the conveyor when it abuts the stop means. The method may also comprise sensing when an article is clear of the stop means. The method may comprise using upstream stop means spaced from the stop means (now referred to as the downstream stop means), the upstream stop means also being movable between the first and second positions, the method comprising the sequence of sensing when an article abuts and is correctly aligned with the downstream stop means in the first position and moving the upstream stop means to the first position, moving the downstream stop means to the second position and moving the upstream stop means to the second position and then moving the downstream stop means to the first position once the article is clear of the downstream stop means. According to another aspect of the present invention, apparatus for spacing a succession of articles along a conveyor according to a method as herein referred to includes stop means movable between a first position in which, in use, articles approaching the stop means are prevented from passing the stop means and a second position in which, in use, articles are able to pass the stop means is characterised in that the arrangement is also for aligning a succession of articles whereby, in use, if an article is not correctly aligned on the conveyor with respect to the direction of travel of the conveyor, the stop means are arranged to move from the first position to the second position after an article has abutted the stop means and after the article has become correctly aligned, the stop means, in use, further being arranged to return to the first position once an article is clear of the stop means. Sensing means may be provided arranged to sense when an article is clear of the stop means. Detection means may be provided to detect when an article is correctly aligned on the conveyor when it abuts the stop means. Upstream stop means may be provided spaced from the stop means (now referred to as the downstream stop means) movable between the first and second positions. The invention may be carried into practice in various ways, but one embodiment will now be described by way of example and with reference to the accompanying diagrams in which: Figure 1 is a schematic plan view of part of a conveyor incorporating an alignment and spacing arrangement, and Figure 2 is a schematic side view of a pair of tins showing the location of stops in relation to successive tins. As shown in Figure 1, a conveyor 10 is driven by two spaced chains 12 in the direction of the arrow 14. A pair of front stops 16 are provided which cooperate with one of the three pairs of rear stops 18, 20 or 22 in dependence upon the size of the tins to be aligned and spaced. For the purposes of illustrating the present invention reference will be made to the stops 18, but it will be appreciated that the operation of the stops 20 or 22 occurs in a similar manner. The stops 16 and 18, can occupy a raised position, shown in phantom lines in Figure 2, or a lowered position, shown in solid lines in that figure. In the raised position the tins 24 or 26 approaching the relevant stops are prevented from moving with the conveyor by abutment with the stops. The tins 24 and 26 are rectangular in plan view with their longitudinal axis extending transversely to the direction of travel. The tins approach the stops at different angles and spacing, as indicated by the outline of further upstream tins 28. The tins leave the stops 16 with their longitudinal axis extending generally perpendicular to the direction of travel and with a predetermined minimum distance between the tins, as indicated by the outline of the tins 30. The stops 18 determine the minimum gaps between the tins leaving the arrangement, and the stops 16 align those tins in the manner described below. When no tins have approached the arrangement for a significant length of time, the stops 18 are in the lowered position and the stops 16 are in the raised position. The first tin 24 to approach the arrangement abuts one or both of the front stops 16. If the longitudinal axis is at an angle other than perpendicular to the direction of travel (as with the tins 28) then the forward edge will contact one of the stops 16 with the conveyor pulling the tin around until the tin is correctly aligned and both of the stops 16 are contacted by the forward edge. When, or just before the front edge abuts both of the stops 16 a pair of spaced proximity switches 32 located just in front of the stops 16 both sense the presence of a tin by both being able to conduct and a timer is set to move the stops 16 to the lowered position after a short period of time, for instance 0.5 seconds, to allow time for the tin to settle against the stops 16. When the stops 16 are moved to the lowered position, the stops 18 simultaneously move to the raised position to prevent the next tin 26 from advancing immediately. As can be seen from Figure 2, the width of the tins are tapered inwardly and downwardly, and as the stops 18 are thinner than the gap between the tins at their lower region, and as the gap between the front and rear stops is equal to the width of the tins, the rear stops 18 cannot hit a tin located over the stops 18. At the same time that the stops 18 are moved to the raised position a count, whose counting rate is related to the speed of the conveyor, is commenced. When the count reaches a predetermined value, which corresponds to the minimum gap required between tins, the stops 18 are moved to the lowered position. If a tin is already present at the stops 18 then this moves forward. If not, then the next tin approaches the stops 16 unhindered, after passing over the lowered stops 18. Whilst the stops 18 are in the raised position and the count is being made, the stops 16 are returned to the raised position as detailed below, in order that the next tin passing over the stops 18 can come to rest against the stops 16. Once a tin has been released by the stops 16, those stops 16 must not return to the raised position until the base of the tin is clear of the stops. To this end a photoelectric cell 34 is provided adjacent to, and downstream of the stops 16, and when the advancing tin clears that cell 34 the stops 16 are returned to the raised position. The stops 20 are used in place of the stops 18 when the width of a tin corresponds to the distance between the stops 20 and 16, and the stops 22 are used when the width of a tray corresponds to the distance between the stops 22 and 16. The stops 18, 20 or 22 are selected by a rotary switch. The pulses for the count are derived from a sprocket on the main jackshaft of the conveyor and accordingly are directly proportional to the speed of the conveyor. In the illustrated embodiment the predetermined count for releasing the stops 18 is arranged to provide a minimum gap of 3.5 inches between the tins. It will be appreciated that the minimum gap between the tins can be automatically adjusted when another pair of stops are chosen, or the gap can be adjusted separately.

Claims: 1. A method of spacing a succession of articles along a conveyor (10) comprising using stop means (18, 20, 22) movable between a first position in which articles (24, 26, 28) approaching the stop means (18, 20, 22) along the conveyor (10) are prevented from passing the stop means (18, 20, 22) and a second position in which articles (24, 26, 28) are able to pass the stop means (18, 20, 22) characterised in that the method further comprises correctly aligning articles (28) if the articles (28) are not correctly aligned on the conveyor (10) with respect to the direction of travel of the conveyor (10) by the sequence of placing the stop means (16) in the first position, turning an article (28) which abuts the stop means (16) into a correct alignment position by movement of the conveyor (10), the article (24) thereby fully settling against the stop means (16), and moving the stop means (16) to the second position after an article (24) has abutted the stop means (16) and after the article (24) has become correctly aligned and then returning the stop means (16) to the first position once an article is clear of the stop means (16) whilst the conveyor (10) is moving. 2. A method as claimed in Claim 1 comprising always moving the stop means (16) to the second position after an article (24, 26, 28) has abutted the stop means. 3. A method as claimed in Claim 1 or Claim 2 comprising using the movement of the stop means (18, 20, 22) from the first position to the second position to control the spacing between successive articles. 4. A method as claimed in any preceding claim comprising detecting (32) when an article (24) is correctly aligned on the conveyor (10) when it abuts the stop means (16). 5. A method as claimed in any preceding claim comprising sensing (34) when an article (30) is clear of the stop means (16). 6. A method as claimed in any preceding claim in which the stop means comprises upstream stop means (18, 20, 22) spaced from downstream stop means, the method comprising the sequence of sensing when an article (24) abuts and is correctly aligned with the downstream stop means (16) in the first position and moving the upstream stop means (18, 20, 22) to the first position, moving the downstream stop means (16) to the second position and moving the upstream stop means (18, 20, 22) to the second position and then moving the downstream stop means (16) to the first position once the article (30) is clear of the downstream stop means (16). 7. Apparatus for spacing a succession of articles (24, 26, 28) along a conveyor (10) according to any one of the methods of the Claims 1 to 6, the apparatus including stop means (16) movable between a first position in which, in use, articles (24, 26, 28) approaching the stop means (16) are prevented from passing the stop means (16) and a second position in which, in use, articles (24, 26, 28) are able to pass the stop means (16), characterised in that the arrangement is also for aligning a succession of articles (24, 26, 28) whereby, in use, if an article (28) is not correctly aligned on the conveyor (10), with respect to the direction of travel of the conveyor, the stop means (16) are arranged to move from the first position to the second position after an article (24) has abutted the stop means (16) and after the article (24) has become correctly aligned, the stop means (16), in use, further being arranged to return to the first position once an article (30) is clear of the stop means (16). 8. Apparatus as claimed in Claim 7 including sensing means (34) arranged to sense when an article (30) is clear of the stop means (16). 9. Apparatus as claimed in Claim 7 or 8 including detection means (34) arranged to detect when an article (24) is correctly aligned on the conveyor (10) when it abuts the stop means (16). 10. Apparatus as claimed in any of Claims 7 to 9 including upstream stop means (18, 20, 22) spaced from the stop means (16) previously referred to (now referred to as the downstream stop means (16) movable between the first and second positions.

Inventors: MORLEY, GARY
Applicants: TWEEDY OF BURNLEY LIMITED
Application year: 1988
Main classification: B65G47
IPC codes: B65G47