GB2549295A - A food manufacturing apparatus, a tortilla manufacturing system and a method for manufacturing food - Google Patents

Abstract

A food manufacturing apparatus 2, particularly for making tortillas, comprises a conveyor mechanism 8 for carrying food articles, such as dough, along a first direction, and a press system 12 having at least a first platen 14 to press the dough with respect to a support 16 to shape the food article. A drive mechanism provides the system 12 with reciprocating linear motion so that it can press the dough while moving in the same direction and at the same speed as the conveyor belt 8. The process is repeated for the next batch of food articles on the conveyor. The drive mechanism uses a linear electric motor 18 which allows precise and smooth motion of the press 12 and is cleaner than hydraulic or rack and pinion systems. Servomotors 26 may control the vertical movement of the upper platen 14 to control the thickness profile of the tortilla.

Description

A Food Manufacturing Apparatus, a Tortilla Manufacturing System and a Method For Manufacturing Food

The present invention relates to a food manufacturing apparatus, a tortilla manufacturing system and a method for manufacturing food.

In embodiments, the invention relates to a tortilla manufacturing system and system for manufacturing shaped baked products. The invention also relates to a method manufacturing shaped baked products.

The field of systems and methods for the manufacture of dough-based food products includes a number of systems and devices by which a substantially continuous process can be used. Such systems and methods find particular use and application in factories for the production of plural food articles such as tortillas, pancakes, bread rolls, pizza bases and even ice cream articles and the like. Indeed the specific food article that is made can be anything where an initial item or sample of mouldable material is shaped by the application of pressure and possibly also heated so as to be cooked at the same time or just after shaping. US-A-8,770,967 describes and discloses a press for use with a continuously moving conveyor belt such as a press for flattening dough pieces into tortillas on a moving conveyor belt. As explained therein, a difficulty arises in the portion of the manufacturing process directed to the pressing the dough into flat shapes. The elastic nature of bread dough is a problem which necessitates a significant amount of work in the pressing of a ball such as a dough ball into a flat pancake or tortilla-like shape.

In the manufacture of other baked products, similar problems arise. Other examples of baked products might include rolls, pizza bases, pancakes and the like.

Known devices for the pressing of balls of dough into tortilla shapes are disclosed in US-A-5,006,358 and US-A-5,388,503. US-A-5,006,358 discloses an apparatus including a non-stick heat tolerant endless conveyor belt moving at a desired constant speed to position tortilla dough balls between the heated platens of a tortilla press. The press is movable in the direction of the path of travel of the belt at the same speed as the belt when the platens are in their closed position with the dough balls squeezed between them. Thereafter, the press may be opened sufficiently for the upper platen to disengage the flattened dough and then slowed, stopped and move counter-directionally to the direction of travel of the belt. At a pre-determined position, the press is again stopped and reversed to cause it to travel again in the direction of travel of the belt. The platens then close on the dough balls when the press has reached the same speed of travel as the belt, repeating the pressing cycle on the group of dough balls next to the last batch of tortillas that was formed by the press. Thus, by a continual reciprocating horizontal movement of the platens, a continuous stream of formed and pressed tortillas can be made.

The drive mechanism of the ‘358 patent incorporates an electric motor, a drive belt driven by the motor, a gear reduction device having a rotating output shaft and an oscillator drive. The oscillator drive includes gears configured to convert the rotation motion of the output shaft of the gear reduction device into an oscillating motion of a pivot arm. The pivot arm is, in turn, connected to the reciprocating frame so as to move the press in the forward and backward directions. US-A-5,388,503 discloses a high speed food processing device wherein the device has a continuous moving belt of non-stick material for carrying a food product, and upper and lower heat platens capable of moving with the food product so that there is no interruption of the forward movement of the continuously moving belt. The platens start in a rear-most position, clamp the mouldable dough on the non-stick belt and move forward with the continuously moving belt cooking the food product at the same time. Then, the platens release the cooked product and return to the rear-most position starting the cycle again. A single drive mechanism simultaneously drives the continuous forward movement of the non-stick belt and the back and forth movement of the upper and lower platens. The system thus incorporates a number of gear reduction devices and chains or drive belts so as to enable a single drive mechanism to simultaneously drive both the belt and the platens. US-A-2008/0102152 discloses a reciprocating press configured to press articles while moving in synchronicity with a conveyor belt carrying the articles. The press is driven with a rack and pinion system. The press is used for pressing any type of article but is specifically designed for the pressing of pieces of dough for forming tortillas.

It is thus clear that there are a number of systems and devices for the continuous formation of tortillas. However the drive mechanisms for the various known systems are complex and often involve the use of hydraulics. This is undesirable in view of the proximity to a food item and the risk of leakage of hydraulic fluid. US-A-4,938,126 discloses apparatus and methods for producing tortillas. The apparatus comprises a non-stick, heat-tolerant, endless conveyor belt moving at desired constant speeds to position tortilla dough balls between the heated platens of a tortilla press. The press is moveable in the direction of the path of travel of the belt at the same speed as the belt when the platens are in their closed position with the dough balls squeezed between them. Thereafter, the press is opened sufficiently for the upper platen to disengage the flattened dough and then slowed, stopped and moved counter-directionally to the direction of travel of the belt. At a pre-determined position, the press is again stopped and reversed to cause it to travel again in the direction of travel of the belt. The platens then close on the dough balls when the press has reached the same speed of travel as the belt, repeating the pressing cycle on the group of doughballs next to the last batch of tortillas that was formed by the press. The movement of the platens is controlled and driven by wheels and rails. A further example of an apparatus for use in the manufacture of food products is disclosed and described in GB-A-1,504,171. This discloses apparatus including a conveyor belt and a work station which is reciprocally movable along a part of the length of the belt. The work station comprises a press which is adapted to be releasably locked to the belt and to move at the speed of the belt in the direction of movement of the belt. The press is operated at least in part by pneumatically actuated mechanical linkages.

According to a first aspect of the present invention, there is provided a food manufacturing apparatus, comprising, a conveyor belt arranged and configured to carry food articles linearly along a first direction; a press system comprising at least a first platen arranged to cyclically apply compressive force to the food article by pressing the food article with respect to a support, thereby to shape the said food article; a drive mechanism to cause the press system to move in reciprocating linear motion so as to be able to press a first article whilst moving in the same direction and at the same speed as the conveyor belt, and then to repeat the process for a next food article on the conveyor belt, wherein the drive mechanism comprises a linear electric motor. A food manufacturing apparatus is provided that is capable of producing a continuous stream of food articles with the use of a linear electric motor to control the reciprocating movement of a press system with respect to a moving conveyor, in contrast to known system where the movement of such a press system is achieved with complex hydraulics or rack and pinion system, the present system utilises a linear motor. The use of such a motor provides significant advantages. It enables a more precise and smoother reciprocating movement to be achieved. The control of such a device is easier to achieve and such devices typically require less maintenance than known system. The present inventor shave recognised that systems that rely upon conventional lead screw mechanisms to control the movement of the press system are prone to error and breakdown. The use of a linear electric motor addresses this problem.

In an embodiment, a plurality of servomotors are arranged to move vertically the first platen with respect to the support.

The use of servomotors enables accurate control of the vertical position of the first platen with respect to the support. This means that the thickness of food articles to be formed can easily and accurately be controlled or managed.

In an embodiment, the support is a second platen and the press system comprises a plurality of servomotors arranged to move vertically the first platen with respect to the second.

In an embodiment, the food manufacturing apparatus comprises at least two servo motors placed at opposite ends of the upper platen, to independently control the position of the end of the platen to which it is connected.

The provision of a servomotor at each end (either considering length to be along the main axial length of the belt or transverse thereto) enables the relative orientation of the first platen with respect to the support to be controlled and varied as desired. For example it might be that some variation in the thickness of the food article is desired.

The use of independent control of the relative height of different sides or ends of the first platen means this can be easily and accurately achieved.

In an embodiment, the food manufacturing apparatus comprises at least 4 servo motors each independently controllable, each of the 4 servomotors being positioned at a corner of the upper platen.

As with the previous example, in the example, the provision of a servomotor at each comer of the first platen enables an even greater degree of control to be achieved in the final article thickness.

In an embodiment, the food article is a dough ball for formation of a tortilla. In other embodiments, the food article could be anything that is formable on such a conveyor system. Examples include pizza bases, bread rolls, even ice cream articles. In this case refrigeration may be needed in the system as whole and in the platens as well.

According to a second aspect of the present invention, there is provided a method of manufacturing food, the method comprising: conveying on a conveyor belt food articles linearly along a first direction; with a press system comprising at least a first platen, cyclically applying compressive force to the food article with respect to a support, thereby shaping the said food article; with a drive mechanism, causing the press system to move in reciprocating linear motion so as to be able to press a first article whilst moving in the same direction and at the same speed as the conveyor belt, and then to repeat the process for a next food article on the conveyor belt, wherein the drive mechanism comprises a linear electric motor. A food manufacturing method is provided that produces a stream of food articles with the use of a linear motor to control the reciprocating movement of a press system with respect to a moving conveyor. As above, in contrast to known system where the movement of such a press system is achieved with complex hydraulics or rack and pinion system, the present system utilises a linear electric motor providing the same significant advantages. For example, such a method enables a more precise and smooth reciprocating movement to be achieved with accurate control.

In an embodiment, the method comprises controlling the vertical position of the first platen with respect to the second with a plurality of servomotors.

In an embodiment, there are at least two servo motors placed at opposite ends of the upper platen, and the method comprises independently controlling the position of the ends of the platen to which each servomotor is connected.

In an embodiment, the method comprises providing at least 4 servo motors, and controlling each one independently.

In an embodiment, the method comprises positioning each of the 4 servomotors at a corner of the upper platen.

In an embodiment, the food article is a dough ball for formation of a tortilla.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a tortilla manufacturing system;

Figure 2 is a side-on view of the tortilla manufacturing system of Figure 1; and

Figure 3 is an end view of the tortilla manufacturing system of Figures 1 and 2.

Referring again to Figure 1, a perspective view of a tortilla manufacturing system is shown. The manufacturing system 2 although described herein as a system for manufacturing tortillas, could be used for manufacturing any products such as food products whereby a continuous production line is required and shaping of an article on a moving conveyor is performed. For example, the process could be used for the production of shaped bread items, ice-cream articles, pizza bases and indeed any other type of product. The system 2 comprises a base 4 which in use is coupled or secured to the ground 6. A conveyor mechanism 8 is provided. A conveyor belt is arranged to continuously rotate around rollers 10 such as to provide a continuously moving surface for articles such as food articles. In the example of Figure 1, the belt itself is not shown. A press system 12 is provided which comprises, in this example, an upper platen 14 and a lower platen 16. The platens 14 and 16 are preferably heated platens although whether or not they are heated can depend on the type of food article being manufactured on the system 2. For example, for the manufacture of tortillas they are preferably heated but for the manufacture of ice cream they may not be. As will be described below, the press system 12 is configured for reciprocating motion in a generally horizontal direction as shown by the arrow X-X’ seen clearly in Figures 1 and 2.

In the example shown, the press system 12 comprises two moveable platens 14 and 16. In one embodiment, the press system comprises a single moveable upper platen and a lower stationary plate. The lower stationary plate, or the moveable lower platen provide a support which, together with the upper platen enables a food article to be pressed. The upper and/or lower platens are shaped such as to ensure that the article formed has a desired shape. For example they could simply be planar and flat or could be provided with mouldings or detents so as to form markings on the food articles being formed. A linear electric motor 18 is provided to control movement of the press system 12 in the horizontal direction. A linear electric motor includes a stator 20 and rotor 28 and is controlled such as to cause movement of the press system backwards and forwards in the horizontal direction as will be described in greater detail below. In this example a linear electric motor is provided on each lateral side of the apparatus and the two work in synchronisation to ensure that he press assembly does not change its transverse alignment during a cycle of operation. In one embodiment a single linear motor is used which is appropriately coupled to the press system to achieve the required movement in the direction XX’. Caterpillar tracks 15 are provided at the sides and can serve to maintain the transverse alignment of the press system during its operation. The tracks 15 serve to guide the power cables to the servo motors and the rotor and do not typically provide mechanical rigidity for the movement of the press system 12.

In addition or instead guides such as a key and slot guiding mechanism can be provided (not shown) to ensure that the press system is only able to move in a straight line during operation. For example, this could be achieved by a guide slot being provided in the housing of the system with a key being provided on a side edge of the lower platen.

The press system 12 comprises an upper platen 14 and a lower platen 16. Both move in parallel with the continually moving conveyor belt such that at all points of their reciprocating horizontal movement, the upper platen 14 is arranged vertically above the lower platen 16. Preferably the belt moves at a fixed speed such that the translational horizontal movement of the belt is a fixed value.

As explained above, in one example, the lower platen is configured not to move and extends for the entire length of the system 2, thereby providing a support for the belt and food articles thereon and a counter surface for the application of pressure with the upper platen. Only the upper platen 14 therefore is configured to move relative to the lower platen 16.

At the input to the tortilla manufacturing system, in the area at the end designated X in Figure 2 and where there is shown an operator 22, raw articles 24 are fed onto the conveyor belt. They can be fed from a previous cutting and shaping machine or manually if desired. Given the high speed of operation of the device and generally automated function, it is preferred that the articles 24 for moulding are fed from an earlier machine in a production line.

The mode by which the food articles are conveyed and then generally subject to a forming pressure is similar to that described in US-A-8,770,960, the entire contents of which are hereby incorporated by reference. As described therein, with particular reference to Figure 18 of that patent, the food articles are conveyed in the direction towards X’ and during their progression, they experience a compressive force from the upper and lower platens 14 and 16 of the press system 12. The press system, under action of the linear motor 20 is controlled to move with the conveyor belt at the same speed and thereby the relative horizontal motion as between the conveyor belt and the press system is substantially zero during the period of actual compression or shaping of a food article. This means that a food article can be compressed as if it were on a stationary compression board as opposed to on a moving conveyor belt.

The mechanism by which the press system is controlled and moved is with use of an electric linear motor. An example of a suitable motor would be a linear electric motor such as that manufactured by Bosch Rexrouth.

The typical mass of press system 12 is approximately 3 tons and it is configured to reciprocate at between 20 and 25 cycles per minute.

The rollers 10 take and guide the continually moving conveyor belt which passes between the upper and lower heated platens. The upper platen is arranged to be moved in a vertical direction, as indicated by the axis Y-Y’ in Figure 1. Servomotors 26 are provided to control the movement of the upper platen 14 relative to the lower platen. Typically, motors which are able to provide ten ton of force are used.

The belt is preferably continuously moving so as to enable a continual production of shaped articles. In some examples the belt can be controlled to have a stop/start movement but clearly this may have an impact on the rate at which articles can be produced and so it is preferred that the belt is continuously moving. The press system 12 is controlled irrespective of whether the belt moves continuously or not so as to ensure that when the platens engage with mouldable food articles it is moving at the same horizontal speed as the belt.

The electric linear motor 18 comprises a magnet stator 20 which is generally fixed to the frame 4 of the device. The driving coils 28 travel with the press assembly 12.

The use of a linear motor together with servomotors for controlling the vertical movement of the platens provides a simple and low stress device. This ensures it will be able to last for longer without encountering technical faults.

The various known systems, as described above, rely on the use of ball screws, hydraulics or rack and pinion. Such systems are likely to be dirtier in operation and require greater amounts of lubricant which is undesirable in a food processing environment. The use of a linear motor addresses this problem.

The servomotors 26 are preferably individually controllable by a controller (not shown). This enables the relative position of each of the four corners of the upper platen 14 to be separately controlled and, if desired therefore enable a variation in the thickness of the articles produced. Whilst it will typically be required that an entirely parallel configuration be provided between the lower platen 16 (or support) and upper platen 14, it is certainly possible that in some applications, depending on the food article being manufactured, that a variation in the thickness will be desired. The use of servo motors to drive the upper platen relative to the lower platen in a vertical direction enables this easily to be achieved.

The platens could simply be components used to apply pressure to the food articles or they could also be used to apply heat and to actually cook the articles during, or after, shaping. Indeed the system 2 preferably includes some means for control of the temperature of the platens during the pressing cycle. Depending on the food article being produced the desired temperature profile of the platens can be varied. If cooking or part cooking is required ten one or both of the platens will be controlled to be heated during a compression cycle. If the article is an ice cream then they can be controlled to be at a sufficiently cold temperature so as not to cause undesired melting. However accurate control in terms of timing and temperature is enabled such that a momentary increase in temperature could be applied at the point of release to facilitate clean removal of the moulded ice cream article from the platen.

For clarity and ease of understanding the relative movement of the belt is defined as “horizontal” and the movement of the platens (in the pressing direction) is defined as “vertical”. In normal arrangement within a manufacturing setting these terms will be interpreted as being relative to the floor of the factory. It will be appreciated though that such a limitation in terms of interpretation is not strictly necessary. What is important is that the movement of the belt is in a first direction and the pressing movement of the platens is in a direction substantially perpendicular to it. For example the belt, relative to a factory floor could move upwards or downwards at an angle of, say, 45 degrees, and the platens during pressing could move perpendicular to the belt.

Embodiments of the present invention have been described with particular reference to the examples illustrated. However, it will be appreciated that variations and modifications may be made to the examples described within the scope of the present invention.

Claims (13)

Claims

1. A food manufacturing apparatus, comprising a conveyor belt arranged and configured to carry food articles linearly along a first direction; a press system comprising at least a first platen arranged to cyclically apply compressive force to the food article by pressing the food article with respect to a support, thereby to shape the said food article; a drive mechanism to cause the press system to move in reciprocating linear motion so as to be able to press a first article whilst moving in the same direction and at the same speed as the conveyor belt, and then to repeat the process for a next food article on the conveyor belt, wherein the drive mechanism comprises a linear electric motor.

2. A food manufacturing apparatus according to claim 1, in which the press system comprises a plurality of servomotors arranged to move vertically the first platen with respect to the second.

3. A food manufacturing apparatus according to claim 2, comprising at least two servo motors placed at opposite ends of the upper platen, to independently control the position of the end of the platen to which it is connected.

4. A food manufacturing apparatus according to claim 3, comprising at least 4 servo motors each independently controllable, each of the 4 servomotors being positioned at a corner of the upper platen.

5. A food manufacturing apparatus according to any of claims 1 to 4, wherein the food article is a dough ball for formation of a tortilla.

6. A method of manufacturing food, the method comprising conveying on a conveyor belt food articles linearly along a first direction; with a press system comprising at least a first platen, cyclically applying compressive force to the food article with respect to a support, thereby shaping the said food article; with a drive mechanism, causing the press system to move in reciprocating linear motion so as to be able to press a first article whilst moving in the same direction and at the same speed as the conveyor belt, and then to repeat the process for a next food article on the conveyor belt, wherein the drive mechanism comprises a linear electric motor.

7. A method according to claim 6, comprising controlling the vertical position of the first platen with respect to the second with a plurality of servomotors.

8. A method according to claim 7, wherein there are at least two servo motors placed at opposite ends of the upper platen, and the method comprises independently controlling the position of the ends of the platen to which each servomotor is connected.

9. A method according to claim 8, comprising providing at least 4 servo motors, and controlling each one independently.

10. A method according to claim, comprising positioning each of the 4 servomotors at a comer of the upper platen.

11. A method according to any of claims 6 to 10, wherein the food article is a dough ball for formation of a tortilla.

12. A food manufacturing apparatus substantially as shown in and/or described with reference to any one or more of Figures 1 to 3 of the accompanying drawings.

13. A method of manufacturing a food article, the method being substantially as shown in and/or described with reference to any one or more of Figures 1 to 3 of the accompanying drawings.