Food processing apparatus

A closed food processing vat particularly for use as a cheese curd vat where at least one rotatable vertical shaft within the vat has a pivotally associated cutter frame stopped so the frame when the shaft is rotated in one direction is moved to a cutting position extending as a radius from the shaft with the cutting edge of the blades in the frame leading to a stirring position when the shaft is rotated in the opposite direction with the frame automatically moved as a reaction against the product in the vat to a position at an angle to the radius so that the projection of blades in the frame relative to the direction of rotation is increased to stir the product. The present invention relates to food processing apparatus which has been particularly although not solely designed for use in cheese making.

BACKGROUND TO THE INVENTION 
Modern cheese making techniques require a high level of cleanliness to be 
maintained and this is facilitated by a sealed or totally enclosed cheese 
vat. In such a vat it is necessary to provide means which will cut the 
curd once it has been set and will arrange for the curd to be stirred 
while being "cooked". A typical vat of this more modern type is described 
and claimed in New Zealand Pat. No. 172,299. Different forces require to 
be generated during the cutting and stirring cycles. Preferably, this 
should be achieved simply and in a manner which will allow for some 
adjustment. 
SUMMARY OF THE INVENTION 
Accordingly the invention consists in food processing apparatus comprising 
a vat, at least one rotatable vertical shaft disposed within said vat, 
drive means operable to rotate the shaft in either direction, frame 
support means projecting from said shaft, a cutter/stirrer frame with a 
plurality of blades incorporated therein, said cutter/stirrer frame being 
pivotally mounted on said frame support means to move between two 
positions, with the pivotal axis parallel to said shaft and parallel to 
the blades in said cutter/stirrer frame, the first of the said two 
positions being assumed when the shaft is rotated in one direction with 
the cutter/stirrer frame extending as a radius from the shaft and the 
cutter blades acting as knives projecting a minimum cutting edge to the 
product in the vat, and the second of the two positions being assumed when 
the shaft is rotated in the opposite direction with the cutter/stirrer 
frame located at an angle to the radius so that the projection of the 
blades in the cutter/stirrer frame relative to the direction of rotation 
is increased to stir the product. 
More particularly the invention may be said to consist in food processing 
apparatus comprising a vat with vertical walls defining two communicating 
partially cylindrical chambers of an open figure eight configuration, a 
double coned top closing said vat, a sub frame mounted above said coned 
top, a rotatably mounted vertical shaft centrally located in each 
interconnecting chamber of the vat the upper end of each shaft being 
supported in said sub frame and drivably connected to the said drive 
means, a cutter/stirrer frame supported from each shaft to extend from 
adjacent the shaft to adjacent the walls of said vat with an area of 
intersection through which both frames pass, each frame having a plurality 
of vertical blades with the axis of the blades at right angles to the main 
plane of the frame, a pivotal mounting between the shaft and its 
associated frame with the axis of said pivotal mounting parallel to the 
shaft and located at a distance of less than half the width of the frame 
from the shaft, stop means to control the position of the frame relative 
to the shaft so that when the shaft rotates in one direction the frame 
will extend substantially as a radius from said shaft with the cutting 
edge of the blades in the frame leading and when the shaft rotates in the 
opposite direction the cutter/stirrer frame is moved by reaction against 
the contents of the vat to a second position at an angle to the radius so 
that the projection of the blades in the cutter/stirrer frame relative to 
the direction of rotation is increased to stir the product.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred form of the invention is used as a cheese making vat but it 
will be appreciated that the invention would have application in a broader 
area of food processing technology where it was necessary to both cut and 
stir the contents in the vat. 
The cheese vat 1 comprises a base frame which use a pair of intersecting 
cylindrical vertical wall sections to define an interior of an open FIG. 8 
configuration with chambers 2 and 3. The vat is closed with a double coned 
top 4 through which an access hatch 5 is provided. The vat is normally 
sealed and milk is delivered thereto through a milk inlet 6. A bank of 
valves 7 are located in the walls to remove the contents from the vat 
during the various stages of processing. 
Details of cheese processing will be well known to experts in the art and 
are not described in detail herein. The milk once introduced into the vat 
is set as a curd, the curd is cut and then stirred during "cooking" or 
heating. The present invention is primarily concerned with the cutting and 
stirring device incorporated in the vat. 
Vertical shafts 8 and 9 are centrally located in the chambers 2 and 3. The 
shafts are carried at their upper end by a frame 10 mounted above the top 
4. The frame 10 also supports the drive mechanism 11 having a motor 12 and 
necessary transmission and interconnecting drives which will allow the 
shafts 8 and 9 to be driven in synchronism in either direction. The drive 
is transmitted from a two speed three phase electric motor via multiple 
V-pulleys and two heavy duty reduction units which are hydrostatically 
sealed to prevent escape of lubricants into the vat. It would be possible 
to incorporate a variable speed drive if this was a customer requirement 
and this may be directly coupled to the motor. The sub-frame 10 is a 
stainless steel sub-frame and the drive unit is totally contained within a 
stainless steel cover 13. 
The lower end of each shaft 8 and 9 is supported in a suitable bearing 14. 
Each shaft 8 and 9 has extending therefrom frame support means provided by 
spaced apart arms 15 and 16 projecting normally from the shaft. The top 
arm 15 is braced back to the shaft and pivotal connections are provided at 
the end of each arm to allow the cutter/stirrer frame 17 to be pivotally 
supported. 
The cutter/stirrer frame 17 (illustrated in more detail in FIGS. 4 and 5) 
has a top transverse member 18 and a lower transverse member 19. 
A plurality of vertical blades 22 extend between the transverse members. 
The vertical blades have a sharpened forward edge 23 and a rounded rear 
edge 24. As with the remainder of the vat the whole assembly is stainless 
steel. 
A bottom transverse member 25 is positioned below the transverse member 19 
and a number of the blades 22 extend down to the bottom transverse member. 
The bottom transverse member has a width such as to generate a stirring 
action close to the bottom of the vat during rotation. 
A pivotal connection 20 is provided between the arm 15 and a hinge lug 20a 
projecting from the top transverse member. A similar pivotal connection 21 
is provided between the arms 16 and the lower transverse member 19. The 
pivotal connections 20 and 21 provide a pivotal axis parallel to the shaft 
and are located along the transverse members at a point less than half the 
width of the frame. 
The thus pivotally supported frame is confined to move between two 
positions. 
In one position the cutter will assume a radius extending out from the 
shaft having the inner edge adjacent the shaft and the outer edge adjacent 
the wall of the vat. As the part of the cutter frame extending beyond the 
pivot points 20 and 21 is greater than that between the pivot points and 
the shaft the force generated on this outer part when the frame is moved 
through a substance in the vat may be used to change the position of the 
food. 
The frame 17 is pivotally movable between two stopped positions. A guide 
lug 26 with an aperture therethrough extends from the top of the 
cutter/stirrer frame. A quadrant rod 27 extends from the top of the arm 15 
and passes through the aperture in the guide leg 26. Stops on the quadrant 
tube 27 against which the lug engages to control the position of the 
frame. 
The operating mode of the invention is depicted diagrammatically in FIGS. 2 
and 3. In the first or cutting mode, (as shown in FIG. 2) the frames 17 
are caused to move to a position where they extend as a radius from the 
shafts 8 and 9 and have the cutting edge 23 leading to cut the curd. The 
blades 22 at this position will project a minimum area relative to the 
direction of rotation and a clean cutting action will be achieved. As 
stated above the resistance generated by movement through the curd will 
automatically cause the frames to move to the position as illustrated in 
FIG. 2 when rotated counter-clockwise. There is an area of intersection 
where the curd is cut by both frames. Also movement of the frames tends to 
advance the curd so that eventually it is all caused to move through the 
area of intersection. The frames in their cutting mode are able to produce 
an evenly cut curd. 
When the shafts 8 and 9 are rotated in the opposite direction, i.e. 
clockwise, the cutter/stirrer frames 17 move to the stirring position, as 
shown in FIG. 3. The resistance to movement of the frame through the curd 
rotates the frame about the pivots 20 and 21 until the stop on the 
quadrant tube 27 is engaged. The frames are now arranged at an angle to 
the radius. This means a projection of the area of the members of the 
frame and particularly the blades produce a rolling stirring action to 
within the vat. The stop 28 along the quadrant 27 is preferably adjustable 
to control the position of the frame in the stirring mode and this allows 
a means to regulate the stirring action. 
The stirring action can take place during the part of the process when heat 
is being applied to "cook" or harden the curd. The heat is applied during 
the cooking cycle by a controlled falling film of hot water passing down 
over the outer wall of the vat. This film of water passes down through an 
insulated water jacket and is controlled so that the surface temperature 
does not exceed 60.degree. C. This effectively avoids "burn on" problems. 
Because of the controlled cooking temperature and the complete and complex 
agitation caused by the stirring mechanism according to the present 
invention each curd particle is gently and properly cooked.