CA1331287C

CA1331287C - Ice making apparatus

Info

Publication number: CA1331287C
Application number: CA000573478A
Authority: CA
Inventors: Stefan Ssoby Jensen; Douglas James Lyon; Jeffrey Bruce Cage; Robert Reid Niblock
Original assignee: VIKOOL Pty Ltd
Current assignee: Heat and Control Pty Ltd
Priority date: 1987-07-31
Filing date: 1988-07-29
Publication date: 1994-08-09
Anticipated expiration: 2011-08-09
Also published as: DE3855557D1; DK26290A; NZ225627A; DK172831B1; FI92758B; JP2927439B2; EP0380502A4; FI92758C; EP0380502A1; EP0380502B1; DE3855557T2; WO1989001120A1; FI900484A0; DK26290D0; ATE143126T1; JPH02504423A; ZA885628B

Abstract

ABSTRACT
This invention relates to apparatus for continuous production of flake ice. The apparatus comprises one or more refrigerated discs (20) mounted on a hollow shaft (18, 21) (71). Each disc (20) rotates in the vertical plane and includes a plurality of narrow internal channels (30) which extend substantially over all of the operative portion of the disc (20) and are of substantially equal length. The disc(s) (20) form(s) the evaporator of a refrigeration circuit, and an evaporative refrigerant is circulated to the channels (30) in each disc (20) via the hollow shaft (18, 21) (71). During each cycle, water is applied to both external flat surfaces of each disc (20) at a first angular location and the film of water which adheres thereto freezes a the disc (20) rotates. The ice sheet so formed is removed from both sides of the disc (20) at a second angular location by scraper blades (40) (75).

Description

-~` 133~287 "ICE MAKING APPARATUS"
The present invention relates to ice making apparatus. In particular, the invention is directed to a machine for making flake ice.
BACKCROUND OF THE INVENTION
Flake ice is made in this sheets approximately 1.5-6.0 mm thick. ~he sheets may be aurved or flat and the thin ice is generally broken into random-sized flakes when harveæted.
Flake ice is particularly suitable for paaking products such as fish or frozen foods as the iC8 flakes can be packed close to the products. In other applications such as chemical processing and conorete cooling, where rapid cooling is important, flake ice is ideal because the flakes present the maximum amount of cooling surface for a given amount of ice.
Flake ice is commonly produced by the application of water to the inside or outside of a refrigerated cylindrical drum. The water ls applied at a first angular location on the drum and adhere~ thereto in a thin layer by surface tension. AB the drum rotates, the water freezes lnto a thin layer of ice, which i6 fraatured by an ice removal device at a second angular location downstream from the first angular looation in the dir~ction of rotation.
The thickness of the flake ice can be varied by ~adjusting the speed of the rotating drum, varying the evaporator temperature, and regulating the water flow on to the fre~ezing surfaae. Sinae flake ice can be made in a continuous operation without being interrupted for a harvest cyale, less refrigeration tonnage is required to produce a tonne of ioe than any other type of manufactured ice when slmilar make up~water and evaporating temperatures are compared.
In known maahines, water i8 applied to only one side of the drum, i.e. either the outside or inside, but not both. As a result, the refrigerated surface on the other side of the drum is unused, and the ice making operation represents an inefficient use of the refrigeration aapacity ' '~
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of the machine.
Furthermore, as the ice removal device is located only on the side of the drum on which ice is formed, the continual unbalanced force applied to that side of the drum to fracture the ice from the freezing surface accelerates the wear on the drum bearings.
A further disadvantage of knoTwn ice making ma¢hines of the drum type is that their capacity cannot ~e readily increased. If increaRed capacity i~ desired, it is usually necessary to install a whole new machine. That is, in addition to installing an extra refrigerated drum, it is also necesæary to in~tall another rsfrlgeration unit inoluding motor, compres~or and conden60r, and a new drive unit. Any upgrading in capacity will therefore involve considerable expensQ.
With a view to overcoming the above deficribed problems and inoreasing the produat-ion oapacity of ioe making machines, it has been proposed to use refrigerated discs. U.S. Patent No.-3,863,462 describes a large scale flake ice producing machine which oomprises one or more upright refrigerated disas rotatable on a horizontal ~ha~t.
Water or other congealable liquid ~is applied to both surfaces of the disc and frozen lnto sheets of ice as the ;~ disc rotates. Thereafter, the sheets are removed from the disc in ice flakes. Each disc is approxima,~ely 1.8m in diameter and comprises a pair of large round aluminium plates spaced apart about 20mm and sealed at their periphery to form an enclo~ed space. Baffles are placed within the interior of the pace to form rudimentary passage~ through which a coolant is pumped in order to refrigerate the disc surfaces.
However, the flake ice producing machine of U.S.
Patent No. 3,863,462 possesses several inherent disadvantages, including:
~ (a) Due to the large flow passages inside the disc, it is necessary to use a non-evaporative coolant such as brine or glycol. That is, a "boiling" or evaporative refrigerant which cool~ by direct ~ : ~
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3 1331~7 expansion is not suitable for use in the disc of U.S. Patent No. 3,863,462. Brine and glycol have low cooling capacity and large amounts of such coolants must be pumped through the disc in order to achieve the required eooling.
tb) Since a aoolant such a~ brine or glycol must be used, a separate refrigeration plant is required in order to chill the brine or glycol.
(e) The discs are diffieult to manufacture accordiny to the toleranees required. The 1.8m diameter discs must be cast and machined, and welded at their periphery, yet the flat outer surfaces of the discs must not vary from the plane in which they rotate by more than 1/8 mm.
For the foregoing reasons, the ice making machine of U.S. Patent No. 3,863,462 is not considsred to be co~mereially aceeptable.
It i8 an object of the prssent invention to overeome or ameliorate at least ~ome of the abovede6eribed disadvantages of the prior art by providing an improved iee making maehins.
It is another objeet of the present invention to provide an improved refrigerated diso for use with the iC8 maki~g machine.
SUMMARY OF ~HE INVENTION
. ~ Aeeording to a first aspeet of the pre3ent invention, thare is provided an ia9 making apparatus eomprising at least one rotatable refrigerated di~c member;
means for applying liquid to both sides of said dise member at a first location, whereby at least some of said liquid ii adheres to both surfaees of said disc member and is frozen as said dise member rotatesj and means for removing the frozen liquid ~rom the sides of said disc member at a second loeation angularly displaced from said first location in the directio~ of rotation; characterised in that each said disc member has a plurality of relatively narrow internal channels for pa~sage of an evaporative coolant therethrough, said ~;channels extending substantially over all of the operative .

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4 ~ 33~87 portion of the disc member.
Typically, the liquid applied to the disc member is water which is frozen to form ice. The ice is removed in the form of flake ice as hereinbefore described.
The water may be applied to the surface of the disc by rotating the disc through a water trough or the like.
Alternatively, the water may be sprayed onto the disa.
Preferably, the ice removal means comprises a pair of harvesting blades juxtaposed with, and extending radially along respective opposite sides of the disc. Each harve~ting blade does not contact the disc but is spaced therefrom by a small cleara~ce, typically 0.05 -1.0 mm. ~he ice is removed without introduced heat.
- As the disc rotates, each point on the operative surfaces of the disc will undergo the following s~eps in sequence: (1) water will be applied to the disc surface, (2) the water will freeze into ice as the disc rotates with time, (3) the lce will be removed by the ice removal means, and the above sequence is repaated with each revolution of the disc in a continuous process.
It will be apparent to those skilled in the art that ice making apparatus of the present invention has few moving part~ and i8 relativ~ly economical to manufacture.
Furthermore, the ice making apparatus is able to utilize direct expansion rafrigeration with a "boiling" or evaporative refrigsrant thereby enabling higher efficiency and ~reezing capacity to be achieved. Only one refrigeration system is required, the disc(s) constituting the evaporator of the refrigeration system.
According to a second aspect of the invention, there is provided a refrigerating disc suitable for use in an ice making machine, said disc having a plurality of relatively narrow internal channels for passage of an evaporative coolant therethrough, said channels extending substantially over all of the operative portion of the disc.
The disc typically is circular in shape and is adapted for rotation about an axis passing through its geometric~centre.

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, ., ~ . . , Preferably, the disc is of sandwich or laminate construction comprising two halves in which open channels have been etched or machined in patterns which are mirror images of each other. When the two halves are sandwiched together to form the composite disc, opposed open channels form closed internal channels. The pattern of the ahannels i8 such that they extend over substantially all of the plane of the disc and are substantially of equal length so that the disc is cooled evenly.
In a single disc machine, the refrigerated disc has I a central aperture having a collar fitted therein. On one side, the collar receives a hollow shaft delivering the aompressed refrigerant. The collar has a series of-radial ¦ bores, communiaating at their inner ends with the hollo~
lS shaft. At their outer ends, the radial bores communicate I with respective i~lets to the channels extending through the ¦ disa, the channel inlets being located o~ the cylindrical surface of the disc aperture. ~he liquid refrigerant paQses through the hollow shaft and into the internal channels of the disc whereat it evaporates to thereby cool the disc.
~ he channel outlets communicate with another hollow shaft on the oppo~ite side of the collar via a second set of radial bores in the collar. The evaporated refrigerant is extraated through this hollow shaft to the aompressor. The disc, collar and shafts form a single asssmbly which is ; rotated by a motor u~ing a belt or chain drive to a pulley or sprocket on one of the ~hafts.
However, the disc can be rotated in any other suitable manner. For example, the disc can be provided with a toothed perimeter so that the disc can be driven by a cog-wheel gear, either directly or chain-driven.
In a multiple aiSc machine, a number of discs are mounted on a common shaft and refrigerant is fed to the :: :
35~ channels in each disc via a distributer and pipe lead system.
The discs are fed in parallel, and the lengths of the pipe leads are made substantially equal to ensure equal pressure drop in the refrigerant feed to the discs. ~he evaporated ~:
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~33~287 refrigerant can be extracted via the common hollow shaft.
Preferred embodiments of the invention will now be described by way of axample with reference to the accompanying drawings.
5BRIEF DESCRIPTION OF THE DR~WINGS
Fig. 1 is a side elevational view of the ice making apparatus of one embodiment of the invention;
Fig. 2 is a sectional elevational view along A-A of Fig. 1;
10Fig. 3 is a sectional side elevational vi~e,w of the disc mounting arrangement of Fig. 1;
Fig. 4 is a sec~ional vi~w of a quadrant of the di~c of the ice making apparatus of Fig. 1;
Fig. 5 is a s~ctional view of part of the disc of' Fig. 4;
Fig. 6 is a sectional view of part of one half diso of Fig. 4;
Fig. 7 is a sectional elevational view along B-B of Fig. 3;
20Fig. 8 is a sectional slevational view along C-C of Fig. 3;
Fig. 9 is an elevational view of the ice removal means of Fig. 2;
Fig. 10 is an end elevational view of the ice removal means of Fig. 9;
Fig. 11 is a plan view of the ice removal means of Fig. 9;
Fig. 12 is a perspective Vi8W of a multiple disc ice making apparatus according to another embodiment;
3Q Fig. 13 i8 a sectional view of the multipl8 di,sc machine of Fig. 12;
Fig. 14 is a plan view of the ice removal means of Fig. 12;
Fig. lS i6 a side view of the ice removal means of Fig. 14;
Fig. 16 is a sectional view of the shaft of Fig. 12;
and Fig. 17 is a sectional view of the disc mounting on 'r:,. i '~ ,, ' 7 1331~87 the shaft of Fig. 16.
DESCRIPTION OF PREFERRED EMBODIMENT
AS shown in the Figs. 1 and 2, the ice making machine 10 of a first embodiment of the invention oomprises a frame 12 on which are mounted a water reservoir 11 and a pump 13. Water rom the reservoir 11 is pumped by pump 13 through upwardly extending pipe 14 to a pair of water sprays 15 loaated abovs and on respective sides of a rotating refxigerated disc 20. The water sprays are orie~ted to direct water o~to both surfaces of the disc to thereby leave a fllm of water adhering to both disc surfaces. The disc 20 ¦ rota~ec in the direction indicated by the arrow in Fig. 1 and is driven by motor 16 via a belt or chain 17 and pulley 18.
However, the disc 20 may be rotated by any other sui~able means. For example, the disc 20 may be pxovided with a toothed perimeter and driven by a cog-wheel gear either direct~y or by chain.
The refrigerated disc 20 has a plurality of channel~
the~ein and constitutes the evaporator in a refrigeration circuit. The mounting of the refrigerated diso 20 is shown in more detail in Fig. 3. As can ~e sean in that drawing, the disc 20 has a central circular aperture having a circular colla~ 22 inserted therein. On one side, the collar 22 receives a hollow æhaft 18 delivering refrigerant while on it6 other side, the collar 22 receives another hoLlow shaft 21 for removing the evaporated refrigerant. The sha~ts 18, 21, collar 22 and disc 20 are fixed relative to each other and rotate as a single assembly. To enable rotation, shaft 18 is mounted in bearing 25 while shaft 21 is mounted in bearing 23. The bearings 23, 25 are located in respective bearing blocks which preferably are adjustably and removably mounted within the frame 12 of the ice making machine.
Hollow shafts 18 and 21 communicate respectively with the condensor and compressor (not ~hown) of a refrigeration circuit.~ O-ring~ 26, 24 are provided to seal the connections to the hafts 18~ 21 respectively.
Shaft 21 ha~ attached thereto a pulley, sprocket or cog 18 which is rotated by motor 16 via belt or chain 17.

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8 1331~87 Rotation of the pulley 18 in turn rotates the disc/collar/pipe assembly.
The refrigerated disc 20 is shown in more detail in Figs. 4-6. The disc 20 is of laminated construction and comprises two discs 20A and 20B sandwiched together. Each disc 20A, 20B has a pattern of Open channels 30A formed in a ~urface thereof, for example by etching or machining. The channel patterns are mirror images of each other so that when the discs 20A and 20B are bonded together, closed channels 30 are formed. The disc is typically 4-10 mm thick, and the ahannels are typically 3.5 mm wide x 2.5 mm high.
The channel pattern for a quadrant of the disc 20 is shown in Fig. 4. ~he pattern for the bottom right quadrant is the inverse to the illustrated pattern for the top right quadrant, and the patterns for the top and bottom left quadrants are mirror images of the patter~s for the top and bottom right quadrants, respsctively. The chan~el pattern is ~o designed that (a? the ohannels are spread over substantially the whole operative surface of the disc 50 that all points on the surface are close to the refrigerant, and (b) the channals are of substantially equal lsngth 80 that there is uniform pressure drop in the ` rafrigerant in all the channels.
These two features ensure that th~ disc is refrigerated aR uniformly and evenly as possible. Moreover, the provision of a pattern of thin channeIfi enables the disc to be ~refrigerated using an evaporative or "boiling"
refrigerant as opposed to brine. Faster and more efficient cooling of the disa is therefore obtained.
;i Although the illustrated disc is composed of two layers, more than two layers can be used to form the laminated disc if desired.
Each channel 30 has an inlet 31 communicating with the central aperture in the disc. The outlets of the channels 30 are also located on the inner cylindrical surface of the disc, on the opposite side to the inlets.
As shown in Figs.- 3, 7 and 8, the collar 22 has a ~ .
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9 ~331~87 plurality of radial bores 27 on one half which communicate at their inner ends 32 with ths hollow shaft 18 and at their outer ends with the inlets 31 of the channels 30 in the disc 20. On the opposite half, the collar 22 is provided with a plurality of radial bores 29 having outer ends communicating with the outlets 33 of channels 30 and inner ends communicating with axial bores 28 which, in turn, communicate with the hollow shaft 21.
Conden~ed liquid refrigerant is fed via shaft 18 through radial bores 27 in the collar 22 and into the channels 30 in the disc 20 where it evaporates to cool the disc. The evaporated refrigerant is drawn from the channel outlet~ 33 through bores 20 and 28 and out through the hollow shaft 21 to the compressor (not ~how~) in the refrigeration circuit. In this manner, the disc acts as tha evaporator in the refri0eration circuit.
As shown in Fig. 2, ice removal maans 40 are mounted on frame 12 for fracturing the ice formed on the disc from the refrigerated 6urfaces. After being broken off the disc, the ice falls down chute 50 to be collscted in ice bin 51.
An embodiment of a harvesting blada assambly ls ~ shown in Figs. 9 - 11. In this embodiment, harvesting blades i 52 are fixed to the bottom edge of a respective one of a pair of radial arm members 53 whiah in turn are fixed to ~upport 25 plate 51 which i8 fastened by bolt 59 to cross beam 56 in the frame 12 of the ice making machine. The inner ends of arms 53 are supported by pendant arm 54 which i8 pivotally attached to bracket 55 on the machine frame. As this mounting arrangement is supported by the ~ain frame rathsr 30 than the shafts 18, 21, it eliminates pressure on bearings 23 and 25 and prolongs the life of such bearings.
The harvesting blade assembly shown in Figs. 9 - 11 also comprises a bearlng block 58 hsld between a pair of brackets 57 to maintain correct relative alignment between the disc 20 and the working edges of the harvesting blades 52.
The harvesting blade assembly is of simple economic construction yet is easy to adjust and to ~aintain.

~ ", t3312~7 Moreover, the harvesting blade assembly harvests the ice on both sides of the disc 20 at the same angular location so that the forces on the disc are balanced.
Since ice is formed on both sides of the disc 20, the ice making machine of the present invention can be made more compact than known drum machines in which ice i6 formed on only one side of the drum. Moreover, as the freezing surfaces of the di~c are in close proximity to the refrigerant, grsater efficiency i8 achievad. The ice making machine has few moving parts, thereby reguiring less maintenance than existing machines. In the event that maintenance i6 required, the disc/shaft/beaxing assembly shown in Fig. 3 can easily be removed from the bearing mounts in the machine.
The machine can be started and stopped intermittently and the speed of the disc can be varied to produce product~ of different clarity and con~i6tency. A
single 500 mm diameter disc can produce over half a tonns of ice in a twenty-four hour period.
Another embodiment of the present invention i~
illustrated in Figs. 12 to 17, this embodiment utilising a ~- - plurality of refrigerated di6cs. A~ shown in Figs. 12 and 13, the multi-disc ice making maohine of the invention comprises a number of refrigerated discs 70 mounted on a common hollow shaft 71. The shaft 71 is mounted at its ends on oombined bearing and seal assemblies 65. An inlet port 68 : i8 provided at one end of the hollow shaft 71 for connection to a source of condensed liquid refrigerant, while the opposite end of the shaft 71 has an outlet port 67 for a suction connection for the evaporated refrigsrant. The discs 70 constitute the evaporator of a refrigeration circuit in a similar manner to the embodiment of Figs. 1 to 11.
The discs 70 are mounted in a water tank 69, which typ~cally is made of stainless steel or glass reinforced plastic. The tank 69 is mounted on a base 61, which is suitably madP of cast aluminium alioy. Spaced pairs of flanges 72 are formed on the tank 69, each disc 70 passing between a respective pair of flanges 72. Scraper blades 75 l : .

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are provided at the top of respective flanges 72 for fracturing the ice sheet formed on the discs 70 as the discs rotate past the blades.
~he discs 70 and shaft 71 are rotated by a pulley or sprocket 64 coaxially mounted on the shaft 71 and driven, by chain or belt, by a drive motor 63 via a reduction gear box 62. However, it will be apparent to those ~killed in ~he art that other means of rotating the discs 70 may be provided.
For example, the pulley or sprocket 64, or one or more of the disc~ 70, may be provided with a toothed circumference and driven directly by a oog-wheel gear.
The tank 69 is fil}ed with water to the level 80 as indicated in Fig. 13. ~s the disc 70 moves through the water in tank 69, a film o~ water will adhere to both surfaces of the disc due to surface ten6ion. As the refrigerated disc 70 rotates in the clockwise direction as shown, the water adhering to the refrigerated surfaces of ths disc will freeze to form a thin sheet of ice which is subsequently fractured from the disc surface by scraper blades 75 positioned as shown. Any water not adhering to the surface of the disc 70 or not being frozen will fiimply trickle back into the tank 69. Accordingly, there is little wastage of the liguid to be frozen.
Ice production can be increased by reducing the temperature of water in tank 69 to close to freezing point, increasing the speed of rotation of disc 70 and increasing the ilow of refrigerant through the disc 70.
The des`ign and construction of each refrigerated disc i8 substantially as hereinbsfore described with reference to Figs. 4-6.
An exemplary ~orm of the scraper blade is illustrated in Fig6. 14 and 15. Each scraper blade 75 is removably mounted on top of its respective flange 72 by sultable fasteners through holes 77. Each scraper blade 75 comprises a ~eries o~ teeth 76 for fracturing the sheet ice - from the refrigerated surfaces of the discs 70. The scraper blades are hardened and tempered to resist wear. The only substantial wear in the machine is the abrasion of the ice . .... . ~ . ., . . .. ~ .

-12 ~3312~7 against the scraper blades, and the scraper blades 75 can easily be removed for replacement and/or re~harpening.
The feeding of refrigerant to the discs 70 is illustrated in Figs. 16 and 17. A four-way liquid refrigerant distributor is provided at the inlet port 68 of the hollow shaft 71. The four-way distributor comprise~ four copper distributor tubes 81-84 which communicate with the channelz in re~pective disc~ 70. The lengths of the distributor tubes 81-84 from ~he inlet port 68 to thei~
respective discs 70 are made equal in order to obtain equal pressure drop in the refrigerant feed to each disc.
The delivery end of each distributor tube 81-84 is raoeived in a radial bore in a respective collared portion of the hollow shaft 71 on which an associated diia 70 is mounted. Each disc 70 is mounted to a collared portion by ~ean~ of a clamping ring-nut 78. ~n internal elliptloal bore formed i~ the centre of each clamping ring-nut 78 to provide an inlet ohamber 73 between the delivery end o~ the respeetive delivery tube 81-84 and the cha~neils i~ the associated disk. Refrigerant delivered through tubes 81-84 fills the receptiv6 chamber6 73 which communicate with the channel openings 31 of each respective disc 70. Re~rigerant flows through the channels 30 of each respective disc whereat it i6 evaporated to cool the di6cs. The evaporated refrigerant is extraeted via the channel outlets which aommunicate with a suction chamber 74 formed between the shafts 71 and the disc 70 by the elliptical aperture in the elamping ring-nut 78. The suction cha~ber 74, in turn, communicates with the interior of the hollow shaft 71 via slots 79 cut into the shaft 71. The refrigerant is extracted from the interior 80 of the hollow shaft 71 via the outlet port 67 for delivery to the compressor of the refrigeration circuit.
The foregoing descr$bes only some embodiments of the pre ent invention and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention. For example, although a circular disc i6 preferred, the ice making `;:
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machine may use a disc of other shape such as hexagonal or octagonal. ~he construction of the disc can be varied to include more than two layers bonded or brazed together, or alternatively, the disc can be manufactured by sandwiching a pipe coil between two flat metal discs.
In an alternative embodiment of the invention (not illustrated), the disc is held stationary and the ice removed by a rotating blade. The blade can be ~itted with wa~er application means on its trailing side so that as the lsading edge removes the ice from the disc, the trailing edge leaves a layer of water which freezes by the time that the leading edge completes a full revolution. ~he water application means can take the form o~ a series of water jets or sprays.
While the ice making machines have been described with particular reference to flake ice manufacture, the invention i8 not limited thereto. For example, the ice making machine~ of the pre3ent invention may also be use~ to manufacture a ~lush ice product ~rom ~ruit juice or cordial.
On a larger scale, the machines could al80 be u~ed to make imitation snow.
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Claims

1. Ice making apparatus comprising at least one rotatable refrigerated disc member; means for applying liquid to both sides of said disc member at a first location, whereby at least some of said liquid adheres to both surfaces of said disc member and is frozen as said disc member rotates; and means for removing the frozen liquid from the sides of said disc member at a second location angularly displaced from said first location in the direction of rotation of the disc member; characterised in that each said disc member has a plurality of relatively narrow internal channels, and the apparatus further comprises means for passing an evaporative refrigerant through the channels such that the vaporisation of the refrigerant cools the disc member directly.

2. Ice making apparatus as claimed in Claim 1, wherein said channels are substantially of equal length.

3. Ice making apparatus as claimed in Claim 1 or 2, wherein each said disc member is of laminate construction and comprises at least two disc portions in which open channels have been formed in respective patterns which are mirror images of each other, said disc portions being bonded together to form said disc member, and said internal channels being formed by opposed open channels.

4. Ice making apparatus as claimed in Claim 1 or 2, wherein said liquid is water, and the frozen liquid is removed from each disc member in the form of flake ice.

5. Ice making apparatus as claimed in Claim 1 or 2, wherein said means for applying liquid comprises a reservoir of said liquid in which each said disc member is partially immersed.

6. Ice making apparatus as claimed in Claim 1 or 2, wherein said ice removal means comprises a pair of radial blade members juxtaposed with each disc member on respective opposite sides thereof.

7. Ice making apparatus as claimed in Claim 1 or 2, wherein the disc member has a central aperture in which a collar member is fitted, said collar member having a first plurality of radial bores which communicate at their inner ends with a hollow shaft fitted to one side of said collar member and at their outer ends with respective inlets to the channels in the disc member, and a second plurality of radial bores having outer ends communicating with respective outlets of the channels in said disc member and having inner ends communicating with a second hollow shaft inserted on the opposite side of said collar member.

8. Apparatus as claimed in any one of Claims 1 or 2, wherein said apparatus comprises a plurality of refrigerated disc members mounted on a common hollow shaft having an inlet and outlet end, said apparatus further comprising coolant delivery tubes extending between the inlet end of said hollow shaft and the respective mounting of each said disc member on said shaft said delivery tubes being substantially of equal length, and at least one aperture in said shaft at the mounting of each respective disc member on said shaft to provide fluid communication between the outlets of the channels in the respective disc members and the interior of said shaft.

9. A rotatable refrigerating disc for use in an ice making machine, said disc comprising:
a planar member having a plurality of relatively narrow internal channels for passage of an evaporative refrigerant therethrough such that the vaporisation of the refrigerant cools the disc directly, said channels extend-ing substantially over all of the operative portion of the disc, each said internal channel having an inlet and an outlet located near the centre portion of the planar member, the internal channels generally coursing from their respective inlets outwardly towards the perimeter of said disc and thence generally inwardly to their respective outlets.

10. A refrigerating disc, as claimed in Claim 9, characterised in that said disc is of laminate construction and comprises at least two disc portions in which open channels have been formed in respective patterns which are mirror images of each other, said disc portions being bonded together to form said disc member, said internal channels being formed by opposed open channels.

11. A disc as claimed in Claim 10, characterised in that said open channels are formed in said disc portions by etching.

12. A disc as claimed in Claim 9, wherein the channels are of equal length.

13. An ice making machine comprising:
a rotatable refrigerated disc, the disc having a plurality of narrow internal channels of generally equal length extending substantially throughout all of the disc;
means for passing an evaporative refrigerant through the channels such that the vaporisation of the refrigerant cools the disc directly;
means for rotating the disc;
means for applying water to both sides of the disc at a first location in the machine whereby, in use, a thin layer of water remains on the surfaces of the disc and is frozen as the disc rotates; and ice removal means located at a second location in the machine for scraping off the ice so formed on the surfaces of the disc.

14. An ice making machine as claimed in Claim 13, characterised in that the disc comprises two halves having open channels formed therein in mirror image patterns, the said internal channels of the disc being composite bores formed by opposed open channels of the halves when the two halves are bonded together.

15. An ice making machine as claimed in Claim 13, characterised in that the means for applying water to the disc comprises water spray means on both sides of the disc.

16. An ice making machine as claimed in Claim 13, characterised in that the means for applying water to the disc comprises a reservoir of water in which the disc is partially immersed.