The present invention relates to a machine for the production of pulled-curd cheeses, provided with means of transport of the material using twin augers.

As is known, in the production of pulled-curd cheeses, the curd is rendered plastic or "stringy" by typically soaking it with hot water until it reaches a temperature of at least 60°C.

The curd is then mixed in a stretching machine so as to obtain a fibrous mix; this mix is then reduced into globoid or cylindrical shapes, which are then firmed up by cooling.

The curd or pulled curd, depending on the step of the process, can be made to advance along the processing line and at the same time be mixed by a pair of augers having a center distance that is smaller than the sum of their radii. The augers usually operate inside a channel into which hot water or steam can be fed, depending on the process step.

By way of example, in some known machines the augers may be located in the initial and final parts of the stretching machine and/or, if present, in the final part of the salt dosage unit.

Currently, the augers are driven by an electric motor connected, depending on the power required, either directly to a double reduction unit or, by virtue of a transmission chain, to two mutually meshing gears.

In any case, in currently known machines the two augers move at a constant speed with a fixed offset, which is normally zero, i.e., the helixes of one auger are inserted exactly halfway between the helixes of the other auger.

A different offset can be chosen at the design stage, but once defined, it can no longer be adjusted.

The aim of the present invention is to provide a machine for the production of pulled-curd cheeses, provided with means of transport of the material using twin augers which offer greater possibilities of adjustment in relation to the transport and mixing actions performed by the augers on the curd or on the pulled curd.

Within the scope of this aim, an object of the invention is to provide a machine that allows to perform said adjustment in a simple manner and without requiring the disassembly of components.

Another object of the present invention is to provide a machine that is compact, with low production and maintenance costs and limited energy consumption.

This aim and these and other objects that will become better apparent hereinafter are achieved by a machine for the production of pulled-curd cheeses, provided with means of transport of the material using twin augers, having the characteristics illustrated in claim 1, while the dependent claims define other advantageous characteristics of the invention.

Further characteristics and advantages of the invention will become better apparent from the description of a preferred but not exclusive embodiment of the machine, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a schematic lateral elevation view of a portion of a generic machine for the production of pulled-curd cheeses according to the invention;

Figure 2 is a sectional view of the machine of Figure 1 taken along the sectional plane II-II;

Figures 3 and 4 are two views, similar to Figure 2, of the machine programed according to a first embodiment of the invention in two different operating configurations;

Figure 5 is a chart which plots the speed profiles of the two augers in a second embodiment of the invention;

Figure 6 is a chart which plots the speed profiles of the two augers in a third embodiment of the invention;

Figure 7 is a chart which plots the trend over time of the distance between two homologous points of the two augers that can be obtained by means of the speed profiles of Figures 5 or 6;

Figure 8 is a chart which plots the speed profiles of the two augers in a fourth embodiment of the invention;

Figure 9 is a chart which plots the trend over time of the distance between two homologous points of the two augers that can be obtained by means of the speed profiles of Figure 8;

Figure 10 is a chart which plots the speed profiles of the two augers in a fifth embodiment of the invention;

Figure 11 is a chart which plots the trend over time of the distance between two homologous points of the two augers that can be obtained by means of the speed profiles of Figure 10;

Figure 12 is a chart which plots the trend over time of the distance between two homologous points of the two augers according to a sixth embodiment of the invention.

By way of non-limiting example, the figures cited above show a generic machine for the production of pulled-curd cheeses, generally designated by the reference numeral 1. The machine 1, which can be a stand-alone apparatus for the transport and mixing of material such as curd to be stretched or pulled curd, or a portion of a complex machine, for example the initial portion of a stretching machine, comprises:

- a hopper 2 for loading the material;

- a transport channel 3 arranged at the bottom of the hopper 2 which in the example described here is open in an upper region in order to receive the material from the hopper 2 and has an outlet end 5 which is open to discharge the material;

- transport means 6 accommodated in the transport channel 3 in order to guide the material toward the outlet end 5. In a per se known manner, the transport means 6 comprise a pair of motorized augers 8, 9 having parallel axes and, preferably, a center distance smaller than the sum of their radii.

According to the invention, the augers 8, 9 are driven by respective independent motors 10, 11 which are controlled individually by a control unit CU which is programmed to allow continuous adjustment of the offset between the augers 8, 9 by varying the speeds of the motors 10, 11.

In a preferred embodiment, shown in Figures 1-4, the augers have helixes with discordant orientations and rotate in opposite directions in order to maximize the mixing action.

In the simplest case, the control unit can be programmed to turn the augers 8 and 9 at a same speed, which can be constant or variable. In this case, the difference between the speeds remains constant and so does the distance between two homologous points of the augers. By virtue of the use of independent motors, said distance can be adjusted quickly and continuously so that the helixes of one auger are exactly halfway between the helixes of the other auger, as shown in Figure 3, or in any position between the two extreme positions shown in Figures 2 and 4, said extreme positions being determined by the need to avoid interference between the augers.

The charts of Figures 7, 9, 11 and 12 plot the trend over the time t of the distance d between two homologous points of the augers, by applying thereto differentiated speed profiles according to different embodiments of the invention, said speed profiles being shown in the charts of Figures 5, 6, 8 and 10.

In particular, in Figure 5 one of the two augers moves at a constant speed v, as shown by the line Al, while the other auger varies its own speed v according to a sinusoidal curve as shown by the line A2. Therefore, the difference between the speeds follows a sinusoidal curve as shown by the line AV, and the distance d also varies according to a sinusoidal curve, as shown by the line D in Figure 7.

As the person skilled in the art will appreciate, advantageously the direction of rotation of the auger that rotates at a variable speed is never reversed, and this allows to limit losses due to inertia and to the wear of the transmission elements.

In Figure 6 both augers vary their own speeds v according to sinusoidal curves in phase opposition, as shown by the lines Al', A2'. Therefore, the difference between the speeds v varies according to a sinusoidal curve, as shown by the line AV and in this case also the distance d varies according to the sinusoidal curve shown by the line D' in Figure 7.

As the person skilled in the art will appreciate, advantageously the direction of rotation is never reversed in this case also.

Moreover, the use of two augers that vary their speeds in phase opposition, with respect to the background art in which one of the augers rotated at a constant speed, allows to reduce the maximum rotation speed and accordingly reduce the power of the motor and therefore the energy consumption.

In Figure 8 the two augers have speed profiles which substantially follow square wave curves in phase opposition, shown by the lines Al", A2". The maximum difference between the speeds v is such that the distance d varies according to a substantially sawtooth curve, as shown by the line D" in Figure 9.

In Figure 10 the two augers have speed profiles which substantially follow square wave curves in phase opposition, shown by the lines Al'", A2'", but the maximum difference between the speeds v is reduced with respect to the background art and is such that the distance varies according to a substantially triangular curve, as shown by the line D'" in Figure 11.

Naturally, the person skilled in the art may devise other speed profiles based on those illustrated above by way of non-limiting example. For example, in Figure 12 the distance d varies according to a trapezoidal curve as shown by the line D ^IV and said profile can be generated by a square wave interspersed with periods in which the augers rotate synchronously.

The operation of the machine 1 according to the invention derives directly from what has just been described.

In practice it has been found that the machine according to the present invention, achieves the intended aim and objects.

In fact, as the person skilled in the art may appreciate, the machine according to the invention offers greater flexibility and greater adjustment possibilities in relation to the transport and mixing actions performed by the augers on the curd or on the pulled curd, with consequent optimization of the process to which is dedicated.

Furthermore, the machine according to the invention allows to perform said adjustment in a simple manner and without requiring the disassembly of components.

Furthermore, the machine according to the invention is compact, with low production and maintenance costs and limited energy consumption.

The machine thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the accompanying claims.

For example, although in the embodiment described here by way of example specific reference has been made to the inlet portion of a stretching machine, the mixing and wringing action performed by the augers can be very important in other machines as well, for example in the loading tunnel located at the outlet of said stretching machine or again, where present, at the outlet of the salt dosage unit, where the augers can perform the additional function of homogenizing the product.

Furthermore, according to the specific application, in a different embodiment the helixes might have concordant orientations and rotate in the same direction, thus combining a gentler mixing action with an alternating wringing-expansion effect determined by the different speed profiles of the two augers.

All the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. 102022000005096, from which this application claims priority, are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility; and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.