A METHOD OF EXTENDING ROLLS OF DOUGH AND APPARATUS FOR USE IN SAID METHOD

Abstract: A method and apparatus are disclosed for moulding pieces of dough into long thin cylinders. To avoid an irregular shape of the final product and/or a non-uniform interior dough structure, the pieces of dough are rolled over a working surface while pressure is exerted on each half thereof, distributed over a plurality of adjoining transverse zones, by elements of the working surface. Each of the elements is laterally movable substantially in proportion to the local dough migration. For this purpose the invention provides a compression bed for use in an extender over a movable carrier. The side of the compression bed which faces the carrier is constituted by elements symmetrically arranged relatively to the longitudinal median plane of the compression bed and journalled for lateral movement.

Description: This invention relates to extending dough, that is to say, rolling a piece of dough into a long thin cylinder, which piece of dough may have been premoulded into a shorter, thicker cylinder, for example, a dough ball first sheeted (i.e. flattened into a thick sheet) in a moulder and then curled. Such a relatively short and thick spiral-shaped curled dough cylinder can be rolled into a longer, thinner cylinder by an extending operation, for example, for making long loaves, from which round toasted slices can be made. Extending a piece of dough is in principle effected in a space between two converging surfaces, in which the piece of dough is forced to roll towards the narrower end of the tapering surfaces by the relative movement of the two surfaces. During rolling, the piece of dough is reduced in diameter and extended in length laterally, that is to say, transversely to the direction of rolling. All extending techniques hitherto used, which are distinguished from each other in differently formed and/or differently driven surfaces, have the disadvantage that the dough is insufficiently spared, i.e. the dough is given insufficient opportunity of freely moving sideways from the middle of the piece of dough during rolling, i.e., transversely to the direction of rolling. Such lateral dough migrations, which are inherent in the rolling dough cylinder becoming longer and thinner, encounter increasingly counteracting frictional forces from the surface which moves relatively more slowly or is stationary. These counteracting frictional forces have a destructive effect on the dough surface and give rise to a non-uniform internal dough structure. The oldest known extending technique is that in which the piece of dough is carried by a conveyor belt and is forced to roll under a flat compression plate disposed above the conveyor belt and inclined in the direction of movement of the conveyor belt. In this arrangement the friction experienced by the laterally displacing dough is so high that, to limit this friction, a long extending path must be used, which, however, has the disadvantage that owing to the prolonged rolling treatment the dough structure deteriorates. In order to make for a shorter rolling path in this basic technique, it has been proposed to form the lower surface of the compression plate with grooves and/or ridges symmetrically diverging in the direction of movement of the conveyor belt to impart a given lateral elongation to the dough piece within a pre-determined path of travel. To avoid, in this arrangement, that dough sticks in the grooves, it has been proposed in DE-PS-63l,558 to provide freely rotating rollers, journalled in the compression plate transversely to the grooves, i.e., with the roller shafts converging in the direction of movement of the conveyor belt. In another proposal, disclosed in DAS 21,46,554, the compression plate has been replaced by two symmetrically juxtaposed endless conveyor belts oppositely driven transversely to the direction of movement of the carrying conveyor belt. All these prior techniques disregard the fact that, in a cylinder which is uniformly extended in lateral direction the dough migration from the middle to the sides is not uniform but progressive, that is to say, as a transverse zone of the dough cylinder is further from the middle, more dough must be displaced from this zone, i.e., not only dough from this zone itself must be displaced outwardly, but also dough from zones located more centrally and migrated to the zone in question. Indeed, in each extending technique which disregards this effect, and is based on a constant lateral guidance and/or exercise of force throughout the entire length of both dough cylinder halves, the dough will tend to congest towards the ends, which leads to an irregular shape of the final product and/or a non-uniform interior dough structure. It is an object of the present invention to avoid the above drawbacks of the prior art dough rolling techniques. In one aspect, therefore, the present invention provides a method of moulding a piece dough into a long thin cylinder, which comprises the measures as stated in claim 1. In this manner any dough congestion as a result of friction is avoided. By allowing the dough in each transverse zone, in accordance with this invention, to carry along the pressure exerting elements with which it is in contact as the dough is migrating from the middle in the direction of its lateral ends, the movement of each element is at all times in agreement with the local dough migration. The friction experienced by the dough at the pressure-exerting elements is low and mainly restricted to the friction required to allow the elements to be driven by the dough. Friction may be avoided alltogether by applying the measures of claim 2. Optimum differentiation is achieved by the measures of claim 3. For carrying the method into effect, the present invention provides a dough extending apparatus as disclosed in claim 4. When, in accordance with this invention, the compression bed is longitudinally divided into successive sections each comprising section elements transversely movable independently of elements in other sections, it is possible to increase the capacity of an extender equipped with such a compression bed. In fact, as soon as a roll of dough has left a section and is in the space between the next section and the subjacent carrier, a fresh roll of dough can be supplied and thus a plurality of rolls of dough can be extended simultaneously without specific displacements of dough in one roll and corresponding movements of the elements having any effect on the elements in other sections and hence on displacements of dough in other rolls of dough. In a first embodiment of the compression bed according to this invention, the movable elements are longitudinally oriented rollers each mounted for rotation about its axis. Such freely-journalled side-by-side rollers can be caused to rotate by a roll of dough moving under them and this each to an extent depending on the local and instantaneous dough displacing component, so that dough migrations towards the lateral ends of a dough cylinder being elongated can take place with a minimum of friction. The rollers can extend throughout the entire length of the compression bed, but preferably the compression bed is composed of longitudinally successive sections of series of shorter rollers. Alternatively, the rollers of the compression bed or of one or more sections of the compression bed are drivable in a differentiated manner. In a variant embodiment of the invention, the freely movable elements are longitudinally oriented bars having a curved cross-sectional profile at least at the underside facing the carrier in the mounted condition of the compression bed, said elements being each individually pivotable about pivot axes located above the elements. In this arrangement, too, laterally migrating dough in a dough cylinder rolling under the bars and thereby being laterally elongated can carry along the bars with which it comes into contact in a lateral pivoting movement, with each bar being displaced parallel to itself and retaining its orientation relative to the subjacent carrier. Such pivoting bars can also extend throughout the entire length of the compression bed or be provided section-wise. The bars may be driven in a differentiated pivoting movement. It is clear that the invention is not limited to the embodiments which will be described herein by way of example and that various variants are possible without departing from the scope of the invention. The essential point is that the differentiated, in particular the progressive dough migration from the middle of a dough roll to its lateral ends during the extending treatment is taken into account and this by providing a compression bed to be mounted above a movable carrier, which compression bed comprises a plurality of elements which, while exerting pressure on the dough in the direction of the carrier move laterally along with the dough in some way in such a manner that no frictional forces causing dough congestion are generated between the dough and these elements. Some embodiments of the extender with compression beds according to the present invention will now be described, by way of example, with reference to the accompanying drawings. In said drawings, Fig. l is a diagrammatic perspective view of the extender; Figs. 2A and 2B are cross-sectional views of the compression bed according to the arrows A-A and B-B in Fig. l; Fig. 3 shows a variant embodiment of the compression bed of Fig. l; Fig. 4 diagrammatically shows a compression bed element comprising individually pivotable bars; and Fig. 5 is a diagrammatic perspective view of a compression bed similar to Fig. l, and provided with rollers driven in a differentiated manner. As illustrated in the drawings, in particular Fig. l, a carrier in the form of an endless conveyor belt l extends from a moulder 2 to an extender 3. The moulder 2 comprises sheeting rollers 4 which transform pieces of dough, in particular dough balls into flat disks 5 which are drawn by carrier l under a net 6 and thereby are curled into short thick cylinders 7 without the exercise of pressure. These are drawn by carrier l in the extender under a compression bed 8 mounted above the carrier with an adjustable slope in the direction of transport of carrier l to form a tapering space T therewith. In this space, dough cylinder 7 is drawn by the carrier towards the narrow end, while the cylinder 7 rolls against compression bed 8. As a result of the radial pressure to which it is subjected, the cylinder 7 becomes increasingly thinner with dough migrating from the middle to both ends. The resulting product is indicated at 7c in Fig. l. Two intermediate phases of this transformation of dough cylinder 7 to the longer and thinner dough cylinder 7c are shown in Fig. 2A and 2B, which will be described in more detail hereinafter. In the embodiment of Fig. l, compression bed 8 comprises a frame 9 in which rollers l0 are disposed immediately next to each other and journalled for free rotation about their axes. As will be seen from a comparison of Fig. 2A with Fig. 2B dough cylinder 7 comes into contact with more and more rollers l0 as it advances through space T. During this procedure, the piece of dough experiences a radial pressure which gives rise to vertical reaction forces R. Owing to lateral dough migration from the middle, the dough also exercises a lateral force S on rollers l0, which increases as the point of compression is further from the middle C. In fact, if a dough cylinder 7a, b is divided into a plurality of transverse zones Z then, as the middle zone Z will become thinner, an amount of dough will be displaced to the adjoining zones Zl. From zones Zl, in principle, not only must the same quantity of dough be displaced to the adjoining zones Z2, but in addition, an amount corresponding to the quantity received from the central zone Z, and so on. In practice, this outwardly increasing displacement of dough results in an increasing lateral force S being exercised on the respective rollers l0, as a result of which rollers l0 are rotated about their axes to an increasing extent, as shown by arrows W. When the compression bed according to the invention is used, no frictional forces opposing a free lateral deformation of the piece of dough 7-7c will be exercised thereon anywhere. In the variant embodiment of compression bed 8 and shown in Fig. 3, compression bed 8′ comprises a frame 9 divided into four sections (a)...(d). A plurality of rollers l0a-l0d, oriented in longitudinal direction, is journalled for free rotation in each section. As soon as a dough cylinder moving under compression bed 8′ has left section (a) and rolls further under section (b), a fresh roll of dough can be passed under section (a). In each section, rollers l0a, ...l0d exercise pressure on a passing dough roll in the same low-friction manner as under the compression bed 8 of Fig. l. The capacity of an extender with a compression bed 8′, however, is higher than that of a device employing a compression bed 8. The compression bed construction shown in Fig. 4, in which the element shown forms itself the compression bed, or a section thereof, differs from compression bed 8 and from compression bed 8′ in that the rollers or bars l2 are not journalled for free rotation about their axes, as are rollers l0, l0a-l0d, but are pivotally suspended through arms l3 from pivoting shafts l4 extending in spaced parallel relationship to bars l2 in a frame l5 that can be mounted in an adjustable manner above a movable carrier l (Fig. l). Each bar can pivot from the position shown dotted in Fig. l about its own axis to the position shown in solid lines under the influence of the lateral displacement of a transverse zone Z of a dough roll 7 that is in contact with the bar in question. Fig. 5 shows an embodiment of the compression bed of Fig. l or Fig. 3 in which at least some of the compression rollers l0 are driven through draggers l6, mounted at one of the roller ends, ropes l7 and driving disks l8 mounted on a common drive shaft l9. Differentiation can be effected by varying the diameter of the draggers and/or of the driving disks l8. In the embodiment shown, the diameter of the draggers l6 decreases from the middle to the lateral ends, so that rollers l0 are driven to increasing extent from the middle laterally. When driven rollers l0 are used in a compression bed divided into successive sections, as shown in Fig. 3, the drive can be limited to the last section d or the last sections c and d .

Claims: A method of moulding a piece of dough (7) into a long thin cylinder (7c), which comprises rolling the piece of dough (7) through a tapering (β) space (T) between a carrying surface (1) and at least one transverse row of elongated, substantially rod-shaped elements (10,12) arranged with their axis substantially parallel to the direction of movement of the carrying surface (1) while exerting pressure on each half of the dough piece (7) by means of said rod-shaped elements (10,12) that are distributed over a plurality of adjoining transverse zones (Z1,Z2,..), said elements (10,12) having at least at their underside facing the carrying surface (1) a curved sectional profile, wherein at least said undersides of said pressure exerting elements (10,12) are, at each moment, laterally displaced parallel to and in proportion to the instantaneous rate of lateral dough movement in the underlying transverse zone (Z, Z1,..) of the doughpiece (7). A method of moulding a piece of dough into a long thin cylinder as claimed in claim 1, wherein use is made of pressure exerting elements in the form of rollers (10) mounted for rotation about their axis, characterized by driving (16-18) each of said pressure exerting rollers (10) at a rate substantially in proportion to the calculated rate of local dough migration in underlying transverse zone (Z, Z1,..) of the doughpiece (7) between said particular roller (10) and said carrying surface (1). A method as claimed in claim 1, characterized in that, as viewed from the middle (C) of the rolling zone to the lateral ends thereof and/or from the beginning (d) of the rolling zone to the end (a) thereof the rollers (10) are driven to an increasing extent. A dough extending apparatus (3) for moulding a piece of dough (7) into a long thin cylinder (7c), which comprises a carrying surface (1) and a compression bed (8) having a frame (9) mounted over said carrying surface (1) in an adjustable manner to form a space (T) therewith tapering (β) in the direction of movement of the carrying surface (1), characterised in that longitudinally oriented pressure exerting rollers (10) are rotatably mounted in said frame (9) and distributed over a plurality of adjoining transverse zones (Z, Z1, ..), and in that driving means (16-18) are provided for driving each of said pressure exerting rollers (10) at a rate substantially in proportion to the calculated rate of local dough migration in the transverse zone (Z, Z1,..) between each particular roller (10) and said carrying surface (1).

Inventors: BENIER, JOHAN
Applicants: BENIER B.V.
Application year: 1987
Main classification: A21C3
IPC codes: A21D8, A21C3, A21C7, A21C11, B65G15