WO1995028087A1

WO1995028087A1 - Moulding of food products

Info

Publication number: WO1995028087A1
Application number: PCT/GB1995/000810
Authority: WO
Inventors: William Charles Cobb; Richard Ernest Snell
Original assignee: APV PLC
Current assignee: APV PLC
Priority date: 1994-04-14
Filing date: 1995-04-10
Publication date: 1995-10-26
Anticipated expiration: 1996-10-14
Also published as: AU2218195A; GB9407382D0

Abstract

A succession of individual dough pieces (1) on an in-feed conveyor (2) are conveyed under a pre-flattening roll (3) to be discharged between the first pair of rolls (4 and 5) of a moulding head (6). The moulding head (6) consists of two pairs of driven rolls (4, 5) and (7, 8) positioned one below the other and offset so that the line made between the centres of successive rolls (4) and (7) forms and angle of approximately 60° with the horizontal. The position of roll (5) is adjustable with respect to roll (4) and is set to give a predetermined centre distance between rolls (4 and 5). The centre distance between rolls (4) and (7) and rolls (5) and (8) is arranged to create a minimum gap (approximately 1 mm) between the roll surfaces, to facilitate the omission of scrapers or deflectors. Roll (8) of the second pair of rolls is similarly adjustable to that of roll (5), both adjustment means are arranged to maintain the minimum gap between the surfaces of roll (5) and (8). Additionally, roll (8) has a means for exerting a controlled pressure onto the dough pieces. The pinned dough piece (9) is discharged onto an intermediate conveyor (10) and passes under a chain-mail coiler (11). The coiled dough piece (12) is then conveyed under a pressure board (13) to set its length. The finished dough piece (14) is then discharged into a baking tin (15).

Description

MOULDING OF FOOD PRODUCTS

This invention relates to the moulding of mouldable food product material and particularly, but not exclusively, to the moulding of bread dough, and to a moulder panner assembly for bread dough.

Traditional designs of bread moulder panner assemblies take individual dough pieces after first proving and press them out to a specified thickness between successive pairs of rolls in a moulding head. The pairs of rolls are set so that in operation the thickness of the individual dough pieces is progressively reduced as they move through the moulding head; transfer of the dough pieces is facilitated by locating non-contacting scrapers and/or deflectors between successive pairs of rolls. The pinned dough pieces are discharged from the moulding head onto a conveyor belt and coiled by means of passing the pieces under a trailing piece of chain-mail. The coiled pieces are made to roll under a static pressure board mounted over the conveyor; the pressure board acting on the dough pieces causes each to extend to a predetermined length to match the baking tins before being discharged into baking tins.

Since the removal of potassium bromate from the list of permitted additives achinability of doughs made from EC wheats, and or similar lower protein wheats, has become more difficult and more sensitive to dough damage, most particularly doughs mixed to the Chorleywood Process. Current moulders have inadequate means to address the problems of reduced machinability and rely on operator skill in setting up an individual machine in order to avoid dough damage; regardless of any possible deterioration of the dough machinability, an improvement in machine operation is still desirable; the relatively poorer machinability of the present doughs can also cause machine stoppage due to the dough sticking to the rolls of the moulding head when, in error, two dough pieces are supplied at the same time (known as 'doubles'). We have appreciated that there is a need for a new moulder where the moulding head is: sympathetic to dough condition, needs less operator skill to set up and maintain correct operation, avoids potential dough snagging points, keeps control of the dough pieces, is self-cleaning as much as possible and deals with doubles without jamming.

The term 'dough' will be used hereinafter to include food product materials that are mouldable in a similar manner to bread dough.

According to one aspect of the invention we provide a dough moulder suitable for pinning a succession of individual portions of dough fed thereto, the moulder comprising at least two pairs of driven rolls, each pair of rolls being provided with respective adjustment means for adjusting the centre distance of the second roll of the pair from the first roll thereof, characterised by the first rolls of successive pairs having their peripheral surfaces closely spaced from one another, the second rolls of successive pairs also having their peripheral surfaces closely spaced from one another, the successive pairs of roll.s being at a lower level than the preceding pair of rolls, and the close spacing of said peripheral surfaces of successive rolls permitting the omission of a scraper and/or deflector associated with the rolls.

The individual portions of dough fed to the first pair of rolls may be rounded portions or pre-flattened portions.

The close spacing of the first rolls of successive pairs of rolls, and that of the second rolls, can enable the dough moulder to operate without the need for any scraper and/or deflector between the pairs of rolls, because the closely spaced rolls are self-cleaning, and because the resulting close spacing of successive pairs of rolls means that the leading end of a dough piece that has been partially pinned by the first pair of rolls will be directed into the bite between the successive pair of rolls without sagging sufficiently to need a deflector.

We are aware that it has been proposed in dough moulders of the type disclosed in GB 741632 to have the rolls in close proximity, but in that type a compression space is defined between four rolls, the space being completely filled with dough which is sheeted out into a continuous sheet.

The spacing between the peripheral surfaces of the rolls of successive pairs is preferably less than 1 mm.

The adjustment means of each of the adjustable rolls is arranged so as to maintain the respective gaps between successive rolls.

The diameter of each roll is selected to ensure that the dough piece may be in contact with two pairs of rolls for a range of dough piece sizes to be produced. In this way the use of dough deflectors or scrapers is avoided by providing self-cleaning and self-guiding characteristics to each pair of rolls for the required range of dough piece sizes.

Preferably one of the rolls in the second or final pair of rolls is subjected to a biassing means to provide an adjustable pressure relief facility, the biassing means being arranged to urge relatively together the rolls of the final pair against an adjustable stop means which determines the minimum spacing of those rolls. The relieved roll can move away in a predetermined fashion from the other roll in the pair under the action of the dough load.

A tighter dough will cause the biassed roll to move away from the other roll of the pair more than with a soft dough.

By measurement and analysis of the resultant movement of the biassing roll the biassing pressure may be altered to compensate for variations of consistency or size of the dough pieces. Additionally, the gap setting between the final pair of rolls, determined by said stop means, coupled with suitable control of the pressure relief setting will enable a taper to be set in the leading and trailing edges of the pinned dough piece (see Figure 2). This provides for a tighter coil to the pinned dough piece.

Also this feature can provide for easy separation of the rolls for access for cleaning by the operator.

Preferably the biassing pressure exerted on the dough piece by the final pair of rolls is provided by pneumatic means.

Alternatively, control of the pressure exerted on the dough piece by the final pair of rolls is arranged by sprung actuation means.

Tests have proven that for a particular dough there is a limiting final gap setting for optimum dough pinning. Below this limiting gap setting no significant reduction in dough piece thickness is achieved due to the recovery within the dough. The pressure relief facility enables the limiting final gap to be maintained during normal use, yet accommodate doubles by separation of the rollers, and removes the need for constant operator attention.

The main criterion for bread quality is the final roll gap setting, a secondary criterion is the reduction ratio between the pairs of rolls. Tests have shown that a 2:1 ratio from first gap setting to last is optimum for standard European doughs. A ratio of up to 4:1 may be the optimum for other doughs such as American.

Preferably the geometry of adjustment means controlling the centre positions of the rolls is arranged to maintain a set between the gap settings of the first and the final roll pairs at all settings of the gap adjustment control of the first pair. This can be arranged by suitable linking of the adjustment means. The surface speed ratio between the pairs of rolls is set to compensate for the reduction in thickness and elongation of the dough piece. Typically for European doughs this ratio is set for a 20% speed increase of the final pair over the first pair (at speed ratio figures of above 20%, skidding of the rolls on the dough piece would occur which could damage the dough). For other doughs, such as American, a ratio of 40% is optimum.

The arrangement is preferably such that the relative speed of rotation of the final pair of rolls in the moulding head is maintained to be a fixed percentage greater than that of the first pair of rolls.

Some degree of stretching of the dough piece can be expected when it moves through the moulding head; the thickness of the piece is reduced progressively and the work input to the dough at each stage is complementary. The dough piece is preferably pre-f1attened to ensure there is a positive take up into the first pair of rolls without hesitation.

By locating the discharge of a pre-flattening conveyor close to the first pair of rolls of the moulding head, with the subsequent vertical drop, between the out-feed end of the pre-flattening conveyor and the nip of the first pair of rolls, set to a minimum, control of the dough piece is maintained and damage to, or deformation of the dough piece is avoided prior to the pinning operation.

In a preferred embodiment there are only two pairs of rolls.

According to a second aspect of the invention a moulder panner assembly comprises a dough moulder as claimed in any one of the preceding claims in combination with conveyor means suitable for supplying in use baking pans to the out-feed end of the dough moulder, the arrangement being such that in use the dough moulder is operable to feed the moulded dough pieces into the baking pans.

A moulder panner assembly in accordance with the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which:

Figure 1 is a perspective view of the moulder panner assembly,

Figure 2 is an enlarged side view of the intermediate conveyor showing a selected dough piece, and

Figure 3 is a side view of the rolls to indicate the action of an adjustable linkage.

A dough piece 1 is placed centrally on an in-feed conveyor 2 and is conveyed under a pre-flattening roll 3. The dough piece is discharged from the conveyor between the first pair of rolls 4 and 5 of a moulding head 6. The moulding head consists of at least two pairs of rolls positioned one below the other and offset so that the line made between the centres of successive rolls 4 and 7 forms an angle of approximately 60° with the horizontal. The position of roll 5 is adjustable with respect to roll 4 and is set to give a predetermined centre distance between rolls 4 and 5. Roll 4 rotates in a clockwise direction and roll 5 in a counter-clockwise direction. The dough piece is drawn through the first pair of rolls, is pressed out to a predetermined thickness and is discharged between the second pair of rolls 7 and 8, which rotate in similar directions to the first pair. The centre distance between rolls 4 and 7 and rolls 5 and 8 is arranged to create a minimum gap (approximately 1 mm) between the roll surfaces. Roll 8 of the second pair of rolls is similarly adjustable to that of roll 5, both adjustment means are arranged to maintain the minimum gap between the surfaces of roll 5 and 8. Additionally roll 8 has a means for exerting a controlled pressure onto the dough piece. The relative speed of the pairs of rolls is controlled to ensure that the dough piece is held in tension between the successive pairs of rolls in the moulding head 6. The pinned dough piece 9 is discharged onto an intermediate conveyor 10 and passes under a chain-mail coiler 11. The coiled dough piece 12 is then conveyed under a pressure board 13 to set its length. The finished dough piece 14 is then discharged into a baking tin 15.

With reference to Figure 3, the gap ratio between the first and last pair of rolls is maintained by a one-piece link 19, which in this case is obtuse-angled, joining the centres of rolls 5 and 8 to the end of a lever arm at 17. The link pivots about the centre of roll 5 which is mounted by means of an eccentric 16 to the machine frame. The end 17 of the lever arm is pivotally linked to the pressure means 18.

By moving the position of pivot 18, the gap between rolls 7 and 8 can be varied, without affecting the gap between rolls 4 and 5.

By rotation of the eccentric 16, the gap between rolls 4 and 5 can be varied, with sympathetic movement of roll 8 to maintain the fixed ratio at a fixed setting position of the pressure relief means 18.

Claims

1. A dough moulder suitable for pinning a succession of individual portions of dough fed thereto, the moulder comprising at least two pairs of driven rolls, each pair of rolls being provided with respective adjustment means for adjusting the centre distance of the second roll of the pair from the first roll thereof, characterised by the first rolls (5, 8) of successive pairs (4, 5; 7, 8) having their peripheral surfaces closely spaced from one another, the second rolls (4, 7) of successive pairs also having their peripheral surfaces closely spaced from one another, the successive pairs (7, 8) of rolls being at a lower level than the preceding pair (4, 5) of rolls, and the close spacing of said peripheral surfaces of successive rolls permitting the omission of a scraper and/or deflector associated with the rolls.

2. A dough moulder as claimed in claim 1 characterised in that one roll (8) of the rolls (7, 8) in the second or final pair of rolls is subjectable to a biassing means to provide an adjustable pressure relief facility, the biassing means being arranged to urge relatively together the rolls (7, 8) of the final pair against an adjustable stop means which determines the minimum spacing of those rolls.

3. A dough moulder as claimed in claim 2, characterised in that the pressure relieved roll (8) is movable away in a predetermined fashion from the other roll (7) in the pair under the action of the dough load.

4. A dough moulder as claimed in claim 2 or 3, characterised in that the gap setting between the final pair of rolls, determined by said stop means, is coupled with control of the pressure relief so as to enable a taper to be set in the leading and trailing edges of a dough piece being handled by the dough moulder.

5. A dough moulder as claimed in any one of claims 1 to 4 characterised in that the diameter of each roll is selected to ensure that in use the dough piece handled by the moulder may be in contact with two pairs of rolls for a range of dough piece sizes.

6. A dough moulder as claimed in any one of claims 1 to 5, characterised in that the adjustment means of each of the adjustable rolls (4, 7) is arranged so as to maintain the respective gaps between successive rolls.

7. A dough moulder as claimed in any one of claims 1 to 6, characterised in that biassing pressure is exerted on the dough piece handled by the moulder by the final pair of rolls (7, 8), said pressure being provided by way of pneumatic means.

8. A dough moulder as claimed in any one of claims 1 to 6, characterised in that biassing pressure is exerted on the dough piece handled by the moulder by the final pair of rolls (7, 8) said pressure being provided by way of sprung actuation means.

9. A dough moulder as claimed in any of the preceding claims characterised by adjustment means for controlling the centre positions of the rolls so as to maintain a set ratio between the gap settings of the first and the final roll pairs at all settings of the gap adjustment means of the first pair.

10. A dough moulder as claimed in claim 9, characterised in that the adjustment means for controlling the centre positions of the rolls and the gap adjustment means are linked together by a mechanical link (19).

11. A dough moulder as claimed in any one of the preceding claims characterised by speed control means whereby the relative speed of rotation of the final pair of rolls (7, 8) is maintained to be a fixed percentage greater than that of the first pair of rolls (4, 5)

12. A dough moulder as claimed in any one of the preceding claims characterised in that the spacing between the peripheral surfaces of the rolls of successive pairs is approximately 1 mm.

13. A moulder panner assembly comprising a dough moulder as claimed in any one of the preceding claims in combination with conveyor means suitable for supplying in use baking pans to the out-feed end of the dough moulder, the arrangement being such that in use the dough moulder is operable to feed the moulded dough pieces into the baking pans (15).