Description Field of the art

The present invention refers to the field of production of sausages, in particular of mortadella, and specifically it regards an improvement of the knife-holder rotors of the machines for producing sausages and more particularly mortadella. Prior art

In the description of the present patent application, reference will generally be made to mortadella; however, this term will more generally refer to the production of sausages, so as to not overly limit the present invention.

Known in the art of mortadella production lines are machines in which considerable quantities of cold meat (very hard) are continuously inserted in a meat passage channel, where this swine meat is pressed against a plurality of perforated discs (with progressively smaller holes) in order to render it soft and uniform. The meat thus processed is then filled, in separate portions (after the addition of additives known in the field, such as aromas etc.), in respective tubular casing elements for each portion, which are then closed.

These machines still today present many problems.

Indeed, for the processing, very high pressures must be applied in the processing channel/duct by the rotary system, which is constituted by the rotation shaft of the knife- holder rotors and by the knife-holder rotors themselves, as well as by the supply auger. The knives press the meat with these very high pressure and cutting forces against the perforated discs, which are fixed, in order to extrude the meat through the holes of the various discs. The diameter of these holes is narrowed between a fixed disc situated more upstream and a fixed disc placed more downstream in the channel. The knives of a rotor must be arranged directly adjacent to the corresponding perforated disc, in order to be able to apply the desired pressure on the meat and push it (in addition to cutting it) against the respective perforated disc, so as to make it exit from the holes of the perforated disc. Different units of this type are normally provided in the channel of the processing machine, i.e. various units comprising stationary perforated discs, as well as knife-holder rotors; for example, a pair of fixed perforated discs arranged in approached position encloses two knife-holder rotors arranged between said two fixed discs. Another knife-holder rotor can be arranged more upstream in the channel, always directly adjacent to the perforated disc arranged more upstream. The processing of the meat occurs via successive steps, from one unit to the next, and in each unit the knives slide (rotating) on the respective perforated disc. Unfortunately, notwithstanding the very high strength of the perforated discs (made of steel), the peaks of pressure acting on the central part of the perforated discs cause a convexity in this central part, such that the knives tend to generate very high friction forces against a stationary perforated disc that is deformed. The consequences are the following:

a considerable quantity of steel particles generated by such friction between the knives and the respective perforated disc is mixed with the meat and is found in the finished product;

- the worn components must be regularly replaced and/or repaired;

- the greater friction developed between the perforated disc which is bent and the knives (which are in contact therewith) generates considerable heat (e.g. a meat temperature up to 70°), causing the organoleptic characteristics of the swine meat to deteriorate; the effect of the heat is also visible to the naked eye in the finished product (rather dark spots in the mortadella), giving the consumer the impression that he has purchased a product of lower quality.

Hence, the object of the present invention is to remedy the preceding drawbacks of the conventional machines for processing swine meat for producing mortadella.

Brief description of the drawings The present invention will now be described as merely exemplifying, non-limiting and non- binding, with reference to a currently preferred embodiment thereof, illustrated in the enclosed drawings, in which: FIG. 1 is a plan view of a meat processing unit, according to the present invention, observing the direction F2 opposite the flow Fl of meat to the interior of the channel of the processing machine (see Fig. 2);

FIG. 2 is the respective side cross section view (executed along the section line A- A of Fig. 1);

FIG. 3 is a view analogous to that of Fig. 2, but for a variant embodiment.

Detailed description of the preferred embodiments

The present invention will now be described in a detailed manner, only for the purpose of assisting a man skilled in the art in comprehending and actuating the invention. All details that are obvious for the man skilled in the art, and in any case irrelevant for the purposes of comprehension of the present innovative concept, will be ignored. Equivalent reference numbers indicate the same components in all the figures. In addition, the details of the materials used for producing the components, subject of the present invention, will not be described; this because all of the already-known relevant materials and technologies can be used, so long as they are not in clear conflict i.e. in contradiction with the present invention and with its objects.

First of all, with reference to Figures 1 and 2, the machine, subject of the present invention, can comprise various units (or sets) like that represented in these figures, within a meat supply and processing channel. Figure 3 shows an improved variant that will be described hereinbelow. A ring nut 1 is fixed in a rigid but removable manner (the details are not essential) to the wall of the supply and processing channel (not illustrated) of the machine (also not shown), Fl (Fig. 2) indicating the direction of the flow of material (meat).

The ring nut 1 rigidly supports two fixed perforated discs 2a and 2b, i.e. stationary with respect to the supply channel of the material, in which 2a indicates the "front" fixed perforated disc and 2b the "rear" fixed perforated disc, front/rear with respect to the arrow Fl . A rotor with knives 3, of conventional type, is mounted "on the front part" with respect to the front disc 2a. The motorized rotation shaft (not shown) of the machine is coaxial with the longitudinal geometric axis of the channel (axis of symmetry of the unit of Fig. 2) and is integral with the supply auger (also not illustrated) which makes the material advance in the channel by pushing it downstream with very high pressures. The same rotation shaft, in addition to rotating the conventional knife-holder rotor 3, to which it is connected, also rotates two knife-holder rotors 4a and 4b according to the present invention, in which 4a indicates the "front" knife-holder rotor of the invention, and 4b the "rear" knife-holder rotor of the invention (the terms front and rear always refer to the direction Fl of the material flow).

The abovementioned supply auger (not shown) is of course situated "above" the conventional rotor 3 in the drawing of Figure 2 and is connected thereto in a manner so as to rotate together therewith.

The knife-holder rotors 4a, 4b according to the present invention have different "spokes" or radial arms, respectively 5a and 5b, which meet at the central hub traversed by the rotation shaft (not shown); see Fig. 1. In other words, as is clear from Figures 1 and 2, the rotor 4a has - in this embodiment - four arms 5a, just like the rotor 4b has - in this embodiment - four arms 5b, said arms 5a and 5b alternating with each other and the two rotors of course being superimposed. In addition, each radial arm (5a or 5b) of these innovative rotors 4a and 4b has a respective substantially rectangular recess for housing a corresponding knife, 6a or 6b. The knives 6a project "upward" from their seat, while the knives 6b project "downward" from their seat, in Figure 2. According to the present invention, unlike the prior art, the knives 6a and 6b are housed in a movable (rather than rigid) manner within the respective seat. Specifically, each knife 6a or 6b is mounted in the relative recess/seat in a manner so as to be able to rotate around a pin, respectively 7a or 7b, inserted transverse (perpendicular) to the radial direction of each spoke, respectively 5a or 5b. This is in particular inferred from figure 1 (double dashed lines).

During the operation of the meat processing machine, the very high pressure of the meat mass over time generates a convexity in the central zone of the front perforated disc 2a and/or in the central zone of the rear perforated disc 2b, more exposed to the pressure peaks; the deformations can also partly occur in the components (spokes) of the rotors, and it is difficult to predict the exact behavior of these deformations. In any case, it is important that the pins 7a and 7b are adapted to allow the oscillation of the respective knife 6a and 6b around them; such knife can thus follow the deformation of the corresponding fixed perforated disc, 2a and 2b.

Before describing the embodiment of Figure 3, it is observed that the embodiment of Figure 2 could be modified by the man skilled in the art in various ways without departing from the protective scope due to such embodiment based on the present inventive concept. For example, on each arm 5 a and/or 5b, there could be more than one knife, for example two shorter knives arranged in a row, inserted in respective recesses with relative transverse pins 7a or 7b.

Preferably, the length of the housing recesses is adapted (even if with suitable minimum clearances for allowing the rotation of the knife around the pin) to the length of the respective knife 6a or 6b; this is so in order to prevent small amounts of meat from entering into the recess, remaining embedded therein, since once hardened such meat could then be difficult to remove. Nevertheless, an elastic material could also be present on the bottom of a recess, in order to render the oscillation of the relative knife "soft" or springy.

Even if, in the figure, the knives have a rectilinear blade that projects from the relative spoke, or radial arm, such blade could also have a slightly curved form. Although in the figures the rotors are formed by a central hub and by four spokes, the number of spokes and/or their form or arrangement could vary according to needs. Also the arrangement of the spokes of one rotor with respect to the other could be different from that illustrated in the figures.

In addition, it is not necessary that each processing unit have a structure like that shown; for example, also the conventional knife-holder rotor 3 (with knives rigidly fixed in the radial arms) could be substituted by a rotor with oscillating knives, according to the present invention, e.g. of the type of a rotor 4a or 4b.

A processing unit can be replaced if it has been excessively deformed.

Various processing units can follow each other along the supply and processing channel, with holes - of the perforated discs - with progressively decreasing diameter.

Preferably, the two rotors 4a and 4b do not form a single body, but rather are simply superimposed, i.e. they are simply separately inserted on the rotation shaft (not represented) of the machine, by means of the non-circular hole of their central hub.

Figure 3 shows a variant with respect to figure 2, in which the hubs of the knife-holder rotors (which are indicated here with 4a' and 4b', respectively), are modified, having respective depressions - on the sides of the rotors that face each other - for receiving a helical spring. Such helical spring 8 acts as a spacer for preventing the two rotors from adhering to each other due to the very high operating pressures.

Otherwise, the embodiment of Figure 3 coincides with that illustrated in Figure 2.