Apparatus for cutting and stirring curd
Apparatus for cutting and stirring curd, comprising a curd vat with a shaft drivable for rotation, which shaft carries a number of cutting frames extending radially from the shaft and arranged on the shaft in staggered relation, each cutting frame having two frame girders, which extend radially from the drivable shaft and between which a lattice work is situated formed from longitudinal knives and transverse knives, the transverse knives being mounted on the frame girders by welding. The transverse knives form openings which are in line, in which the longitudinal knives are received with ample play, while means are provided for substantially preventing displacement of the longitudinal knives in the longitudinal direction.
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This application is a continuation of Ser. No. 09/659,994, filed Sep. 12, 2000, now U.S. Pat. No. 6,257,129.
This invention relates to an apparatus for cutting and stirring curd. Such apparatuses are known from practice and comprise a tank in which a rotatable shaft is situated which carries cutting frames extending radially from the shaft, which cutting frames are mounted on the shaft in staggered relation. The cutting frames each comprise two spaced-apart parallel frame girders, which are mounted by one end on the rotatable shaft and whose other end extends to a point near the wall of the tank. The tank can be arranged horizontally or vertically, the rotatable shaft then being likewise horizontal or vertical.
Arranged between the frame girders is a lattice of longitudinal and transverse knives. The transverse knives extend transversely to the frame girders and are welded to them. The longitudinal knives extend parallel to the frame girders and are mounted on the transverse knives by welding.
Such an apparatus is, for instance, the curd vat marketed by Tetra Pak Tebel under the name of OST4. Such an apparatus is also described, for instance, in U.S. Pat. No. 4,108,058. A variant with two horizontal shafts in a horizontal oval tank is described in U.S. Pat. No. 4,989,504.
All known apparatuses are arranged for stirring and cutting curd which has formed in the tank in that the tank has been filled with milk to which starter and rennet have been added. To that end, the central shaft is driven for rotation, so that the cutting frames move through the curd formed. The cutting frames are usually designed such that the knives and the frame girders form a cutting edge along one edge and are blunt and rounded off along the other edge. Accordingly, rotation of the central shaft(s) in one direction substantially yields a cutting action, while rotation in the other direction substantially yields a stirring action.
A problem presenting itself in the known apparatuses is that they comprise many welds, which must all be polished very well to prevent accumulation of contaminants and bacterial growth. The longitudinal knives can be arranged, for instance, with interspaces of the order of 4 to 5 cm and the transverse knives with interspaces of, for instance, 14.5 to 17.5 cm. A cutting frame can, for instance, have a total width of the order of 50 cm and a length of, for instance, 150 cm. This means that a single cutting frame can comprise, for instance, about 100 rectangular lattice openings, each having four corners where a longitudinal knife or a frame girder is welded to a transverse knife. Each of those welds not only needs to be provided, but also needs to be accurately polished to satisfy the requirements set by government regulations with regard to cleanability. For the welding operation, and in particular also for the polishing operation, however, little space is available within the lattice openings formed by the longitudinal and transverse elements of a cutting frame. As a consequence, the welding work and the polishing work are very time consuming and costly.
In the past, it has been proposed to make the cutting frames of detachable design to obtained a better cleanability. A major drawback of such a solution is that each time a curd vat is to be cleaned, time consuming and cumbersome dismounting activities are necessary.
Accordingly, there is a need for an apparatus of the above-described kind, having a construction such that the necessary welling and polishing work is considerably reduced and simplified, while yet an effective cutting and stirring action and an excellent cleanability remain guaranteed.
According to the invention, to that end, an apparatus for cutting and stirring curd, comprising a curd vat with a shaft drivable for rotation, which shaft carries a number of cutting frames extending radially from the shaft and mounted on the shaft in staggered relation, each cutting frame having frame girders which extend radially from the drivable shaft and between which a lattice work is situated formed from longitudinal knives and transverse knives, the transverse knives being mounted on the frame girders by welding, is characterized in that the transverse knives form openings which are in line, in which the longitudinal knives are received with ample play, and means are provided to substantially prevent displacement of the longitudinal knives in the longitudinal direction.
In the following, the invention will be further described with reference to the accompanying drawings.
Outside the curd container, the shaft 5 is connected by means of a coupling 8 to a shaft 9, which is connected, in most cases coupled directly via transmission means 10, to a drive motor 11. The motor 11 is arranged for rotating the tool 6 around the centerline of the curd vat 1 alternately in one direction and the other.
In this example, the curd vat 1 in its upper part has a manhole 13 which is covered by a manhole cover 13a. In this example, further, another opening is provided in the upper part of the curd container 1, which opening is designated by 14 and is intended for the immersion of a whey sieve 15 in the curd container 1. The whey sieve 15 in this example is supported by a bent pipe 16 which at 17 is rotatably connected to the curd container 1. The curd vat 1 has an outlet 18 at its lowest part. A triangle P indicates a usual level of the curd in the curd vat. It is noted that the invention is also applicable to differently designed curd vats.
The tool 6 comprises a number of cutting frames 19 which are located side by side along the shaft 5, as appears from
Each of the sections may further be fitted at an angle to the shaft 5, as illustrated in
It is noted that in
The openings in the transverse knives can have various shapes, for instance a circular, oval, rectangular or diamond-shaped shape. The edges of the openings, or at least the lower portion thereof, can be provided with cutting edges. Advantageously, the upper edges, or all edges, of the openings may also be sharp so as to obtain a smallest possible contact surface and a smallest possible risk of dirt incrustation.
Examples of receiving openings for a longitudinal knife as provided in a transverse knife are schematically shown in
To enhance strength, the transverse knives can optionally have a curved or bent shape, as viewed in cross section, as shown schematically in
In the exemplary embodiment schematically shown in
The above-described construction of a cutting frame enables a relatively simple assembly of the cutting frame with relatively little welding work. Also, by virtue of the nature of the construction with the longitudinal knives mounted in the cutting frame with relatively large play, caking of dirt at the intersections of the longitudinal and transverse knives and adjacent the fixing pin 46 can be effectively prevented.
It is noted that after the foregoing, various modifications will readily occur to those skilled in the art. Thus, as already noted, it is possible to use, at will, single relatively broad transverse knives with an opening therein for the longitudinal knives or pairs of two transverse knives located above each other with recesses located opposite each other. It is also possible to use long U-shaped knives extending substantially throughout the length of a cutting frame, which are optionally fitted in alternation from one end of the cutting frame and from the other end. Further, instead of longitudinal knives bent into a U-shape, straight longitudinal knives having the same length as the cutting frame can be used. It is also possible to use shorter knives which can overlap to allow them to be fixed with a single fixing pin. Alternatively, more than one fixing pin, for instance two, can be used. This also holds if the U-shaped bent longitudinal knives are designed with legs of equal length. Furthermore, when U-shaped longitudinal knives are used, it is, of course, possible to make the legs as long as the cutting frame. Then a single fixing pin will suffice again.
The fixing pin shown in the figures has two bent ends, which means that at least one end has to be bent over after the pin has been placed. Alternatively, other fixing methods are conceivable, such as, for instance, welding the pin to one or both frame girders, or the use of a pin consisting of two parts, which parts, after being arranged at an appropriate position between the frame girders, are attached to each other by screws or welds or the like.
Further, the longitudinal knives can be provided with recesses instead of openings, which recesses receive, with play, a fixing pin which prevents the longitudinal knives from shifting in their longitudinal direction. Instead of a fixing pin inserted through openings, a special transverse knife or transverse element may then be used, which extends in the recesses and which, after positioning of the longitudinal knives, is welded to the frame girders of the cutting frame. Such a fixing method is schematically shown in
According to another alternative, the longitudinal knives can be connected at one of their ends to a transverse knife or a special transverse element by welding.
The free end 58 of the long leg of the longitudinal knife that reaches beyond the transverse knife or transverse element can, if desired, be bent over or be provided with a transverse section, as shown in
These and similar modifications will readily occur to those skilled in the art.
Claims
1. An apparatus for cutting and stirring curd, comprising a curd vat with a shaft drivable for rotation, which shaft carries a number of cutting frames extending radially from the shaft and arranged on the shaft in staggered relation, each cutting frame having two frame girders, which extend radially from the drivable shaft and between which a lattice work is situated formed from longitudinal knives and transverse knives, the transverse knives being mounted on the frame girders by welding wherein the transverse knives have openings which are in line, in which the longitudinal knives are received, while means are provided for substantially preventing displacement of the longitudinal knives in the longitudinal direction and wherein at least a number of said opening are of essentially circular or oval shape each longitudinal knife has a size relative to the size of the openings such that the longitudinal knives are loosely disposed in the openings with a relatively large play.
2. An apparatus as claimed in claim 1, wherein at least a number of said openings are of diamond shape.
3. An apparatus as claimed in claim 1, wherein at least a number of transverse knives, viewed in cross-section have a bent shape.
4. An apparatus as claimed in claim 1, wherein the means for preventing displacement of the longitudinal knives comprise a transverse knife which is secured to both frame girders and which is connected to the longitudinal knivesthrough welding.
5. An apparatus as claimed in claim 4, wherein said transverse knife has a bent shape in cross-section.
6. An apparatus as claimed in claim 1, wherein the longitudinal knives include a number of U-shapes bent strip like knives, the legs of said U-shaped knives being inserted in adjacent openings of the transverse knives.
7. A cutting frame comprising: a pair of parallel girders, the girders being spaced apart and having a plurality of transverse knives extending transversely between the girders and secured to the girders by welding, the transverse knives having a cutting edge extending transversely of the girders and the transverse knives having a plurality of openings, the openings in one of the transverse knives being aligned with openings in adjacent transverse knives, longitudinal knives each having a longitudinal cutting edge, the longitudinal knives extending through the openings in the transverse knives, the openings being larger in size than the longitudinal knives, the longitudinal knives having means for preventing the longitudinal knives from longitudinal movement.
8. The cutting frame according to claim 7, wherein the longitudinal knives have openings, and wherein the girders have openings aligned with the openings in the longitudinal knives, and wherein the means for preventing the longitudinal knives from longitudinal movement relative to the transverse knives comprises a pin extending through the longitudinal knives openings and through the girder openings that are aligned with the longitudinal knives openings.
9. The cutting frame according to claim 8, wherein each opening in the longitudinal knives is of a size relative to the cross-section of the pin to provide space in the openings around the pin.
10. A cutting frame comprising: a pair of parallel girders, the girders being spaced apart and having a plurality of transverse knives extending transversely between the girders and secured to the girders by welding, the transverse knives having a cutting edge extending transversely of the girders and the transverse knives having a plurality of openings, the openings in one of the transverse knives being aligned with openings in adjacent transverse knives, longitudinal knives extending through the openings in the transverse knives, the longitudinal knives being loosely disposed in the openings with a relatively large play, and means for substantially preventing displacement of the longitudinal knives in the longitudinal direction.
11. The cutting frame according to claim 10, wherein the longitudinal knives have a leading side having a longitudinal cutting edge and a trailing edge, and each opening has a size greater than the size of each longitudinal knife, the openings comprising recesses aligned with the longitudinal knives and having the leading and trailing edges received in the recesses.
12. A cutting frame comprising:
- a pair of girders, said girders being spaced apart from each other and having a plurality of transverse knives extending between the girders, the transverse knives being connected to the girders by welding,
- a plurality of longitudinal knives arranged in substantially parallel relation to the girders and being spaced apart from each other, the longitudinal knives being secured against longitudinal displacement relative to the girders,
- the transverse knives having a plurality of openings, the openings in each transverse knife being in register with corresponding openings of others of the transverse knives and through which the longitudinal knives pass, each longitudinal knife comprising two legs connected by a part.
13. The cutting frame according to claim 12, wherein the part has a “U” shape.
14. The cutting frame according to claim 13, wherein the part is a bent part joining an adjacent pair of the longitudinal knives of unequal length.
15. An apparatus as claimed in claim 1 wherein at least a number of the openings are essentially circular.
16. An apparatus as claimed in claim 1 wherein at least a number of the openings are oval shape.
17. An apparatus as claimed in claim 1, wherein the means for substantially preventing displacement of the longitudinal knives in the longitudinal direction comprises one end of the longitudinal knives being welded to one of the transverse knives.
18. An apparatus as claimed in claim 7, wherein the means for preventing the longitudinal knives from longitudinal movement comprises one end of the longitudinal knives being welded to one of the transverse knives.
19. An apparatus as claimed in claim 10, wherein the means for substantially preventing displacement of the longitudinal knives in the longitudinal direction comprises one end of the longitudinal knives being welded to one of the transverse knives.
Type: Grant
Filed: Apr 9, 2004
Date of Patent: Nov 22, 2011
Assignee: Tetra Laval Holdings & Finance S.A. (Pully)
Inventors: Sijmen Sipma (De Knipe), Sjoerd Huitema (Koudum)
Primary Examiner: Reginald L. Alexander
Attorney: Buchanan Ingersoll & Rooney PC
Application Number: 10/821,280
International Classification: A23L 1/00 (20060101);