US2165573A - Method of and apparatus for cubing ice - Google Patents

Description

July 11, 1939. w C. PFEIL 1 2,165,573

' MISTI-10D OF AND APPARATUS FOR CUBING ICE Filed sept. a, i958 s sheets-sheet 1 July 11, 1939.

W. C. PFEIL METHOD OF AND APPARATUS FOR CUBING ICE Filed Sept. 8, 1938 3 Sheets-Sheet 2 ZMS @@MK @5 July 11, 1939. w, C, PFElL 2,165,573

METHOD OF AND APPARATUS FOR CUBING ICE Filed Sept. 8, 1938 .'5 Sheets-Sheet C5 f( n f2.1

Patented July 11, 1939 PATENT OFFICET '2,165,573 ME'rnon 'or ANnArIPAnATUs Fon. oUBlNG.

Y l or.

'William Giri Pfeil,V Chicagmlll. Y Application September 8, 1938, Serial No. 228,895

zo claims.

This invention relates to a new and novel method of and apparatus for cubing ice.

The invention is particularly directed to certain valuable improvements providing a practical and commercial machinecapable of cubing large quantities of ice with minimum waste.

Machines of this type have heretofore been generally unsatisfactory and have not been commercially successful. Blocks of ice that are to be 1 vcut into small` cubes must be handled quickly if unnecessary loss in the cutting is to be prevented and a sufficient quantity is to be cut, warranting the cost of the construction and operation cfa machine of this type. Moreover, the construc- 'tion must be of a character that the cutting elements will not be distorted as the result of the weight and low temperature of the ice coming into contact therewith. The cutting elements or tubes must be capable oft uniformly producing suflicient heat to effect uniform cutting and should be arranged so that .they will `not be permanently distorted and yet be readily replaceable,

if necessary. Electrically heated elements ,have` been proposed. While certain; features herein disclosed lend themselves to a machine employing electrically heatedv elements, the latter gen- Uerally cool rapidly and loose their heat when brought into contact with ice. They are of'small cross section and tend toretain apermanent stretch when expandedor flexed. On` the ,other hand, where fluid heated tubes have beenV used,

end headers rigidly carrying the tubes have prevented any possibility of compensating for the expansion and stretching of the tubes or for be brought into direct contactwiththe h ot tubes. Moreover, the heated iiuid has been forced to flow from the inlet header to the outlet header in the same direction throughout all the heated tubes. The absence of uniform distribution of heat when all the hot inlet ends are on one side, has caused large blocks to be cut more rapidlyalong this hot side with the result thatthe cutting has been uneven and a greater loss sustained.

' An object of the invention is to provide a machine overcoming the above diiiiculties by means of a structure whichwill receive a cake of ice at one end-and cause the same to move forwardly through the 'machine passing first through a 50 grid of cutting'eleinents to' cut the cake into, say

horizontal slabs, and then to continue the movementof these slabs forwardly along an apron untilthey slide upon va second grid of cutting elements under which "a third grid may be located, wherebylthe slabs are cut into cubes and allowed the rapid contraction .when thecold -ice wouldy (ci. sz-i12) to drop between the cutting elements andinto a receptacle.

Y A further object of the invention is toprov'lde an improved type of cutting element adapted to be suitably carried upon a frame so that it may 5 be readily rremoved for replacement, or repair, if

necessary. f

A still further object of the invention is to provide anrimproved form of-resilient mounting for y the cutting elements to compensate for expanl0 sion, contractionl or i, flexing'movements lthereof and to prevent thereby any tendency toward permanent distortion. .y

Another objectof the inventionV is to provide an improvedI resilient connection foi-*the cutting 15 whereby thev block of ice will be cut relatively uni- 25 formly from side to side. y

Movingparts are eliminated in the operation of the machine. The cake of ice is initially placed uponan inclinedapron. AThe weight of the ice .moves it forwardly against the first grid having 30 its cutting elements preferably horizontally arranged which cut the ice into horizontal slabs as its weight forces it therebeyond. The inclined apron causes the ice to continue itsV own vmov'ement vuntil the 'ice drops upon a second grid, 35 which, while its cutting elements arelikewise horizontally arranged relatively speaking, places these cutting elements transversely'with respect to the cutting elements of the first" grid. A third grid with horizontal cutting elements is disposed o below the second grid whereby thecontinued movement of the ice slabs alongrthe apron and upon the second grid will cause these slabsto be quickly cut into cubes. Thereare no swinging or moving parts which v must change position so 45 as to slow up the cutting `operation ofsuccessive cakes of iceplaced upon the apron at the starting end or cause unevenlycut cubes'. j Other objects and` advantages of the invention will be apparent from vthe ,followingspeciiication when taken in .connection with the accompanyingdrawi'ngsv g n.7. In the'drawingm v kFigure 1 isjaftop pianviewofa machineembodying'the'inventiom- 55 Fig. 2 is a side elevation of this machine;

Fig. 3 is a detail sectional view illustrating the sloping apron;

Fig. 4 is an enlarged detail View looking downwardly upon the cutting elements disposed at the end of the apron for cubing the ice after it has been cut into horizontal slabs;

Fig. 5 is a sectional detail view taken on line 5-5 of Fig. 7 illustrating the resilient mounting provided at the ends of each cutting element;

Fig. 6 is asimilar view taken on line 5 5 of Fig. 7 to illustrate a resilient connection provided between the resilient mounting and the inlet and outlet headers circumscribing the grid frame;

Fig. 7 is a detail view of a portion of a side of one of the grids carrying the cutting elements;

Fig. 8 illustrates diagrammatically the action of the resilient mountings when the cutting ele'- ments are caused to flex by the weight of the ice;

Fig. 9 is an enlarged sectional detail taken on line 9 9 of Fig. 4;

Fig. 10 is a detail view of the cutting elements for first slabbing the the cake of ice horizontally;

Fig. 11 is a detail view illustrating the mountings of these cutting elements at one end and the resilient connections provided between these mountings and the inlet and outlet headers;

Fig. 12 is a detail sectional view taken on line |2--l2 of Fig. 10;

Fig. 13 is a view ofthe forward end of the apron; and

Fig. 14 is a cross-sectional view of a modified form of cutting element. 1

Any suitable frame may be employed to support the parts to be hereinafter described. The drawings illustrate,v however, .vertical uprights 2 and 3 at the front and rear ends, respectively.'

and intermediate vertical uprights 4- and 5. Lower and upper longitudinal irons 5 and I and transverse corner irons 3 connect these uprights into a suitable framework. An apron I5 is supported bythe framework to slope or tilt downwardly from the front end of the machine. Apron i0 may be suitably secured at the front end, say to a transverse iron II, supported by the .end uprights 2 that may extend above longitudinal iron 1 a distance to give apron I5 the proper pitch. Intermediate uprights 4 likewise extend above longitudinal Yirons I to support a frame l2 of a grid I3 carrying .a series of cutting elements I5. Frame I2 may have vertical side members I5 and a top cross: member II, all of suitable angle iron, to permit the mountings kof cutting elements I5 to be carried in one leg of each side member I5. No specific form of at-` tachment between frame i2 and the frame of the machine is necessary.

Apron I0 is preferably ribbed at i9 and provided with side anges 2li, as illustrated in Fig. 13. Flanges 2li may rest upon angle frames 2l, suitably carried by the frame of the machine and supported uponthe uprights 2, 4 and 5 as illustrated in Fig. 2. Ribs I3 eliminate surface contact between the ice cake and apron i3, and thereby facilitate movement of the ice cake downwardly along apron I3 to bring it into quick contact with heated cutting elements l5. The weight of. the ice tends to force the cake into cutting elements l5 so as to allow these cutting elements rapidly to perform their work of slicing the cake into horizontal slabs, which has been illustrated in dotted lines in Fig. 2. At` the discharge end 2|, the apron is preferably curved downwardly, as illustrated particularly inFig. 9, and is cut away at 22 so that a portion of the end may lie between and extend below cutting elements 25.

This second set of cutting elements 25 are arranged as a grid positioned at the end of apron 2li and arranged to lie in the same general direction as apron I0 so as to readily receive the cake of ice sliding along the apron after it has been slabbed by cutting elements I5. In other words, the position of cutting elements 25 allows the cake of ice to slide forwardly, drop from the end 2| of apron ill upon these cutting elements 25, and, if necessary, cause the cake to move forwardly along these cutting elements until it lrests completely thereon, as illustrated by the dotted lines at 30 in Fig. 2. Heated elements 25 will immediately cut into the ice by reason of the weight of the ice forcing it therebeyond. This second cutting causes these slabs of ice cut by elements I5 to be cut into long bars. To cube the ice, a third set of cutting elements 35 are provided below cutting elements 25. Cutting elements 35 are, of course, arranged transverse to cutting elements 25.

These cutting elements 25 and 35 form a grid with a frame 35. Frame 35 is rectangular and is provided with a series of spaced slots 31 that are open at the top and disposed in the vertical leg of frame 35 on all four sides. The frame of the machine may be arranged to receive the horizontal leg of frame 35 as the means of `mounting this grid unit of two sets of cutting elements upon the machine at the end of apron I 0. Slots 31 may be cut along the top of frame 33 so as to admit of ready removal of either of the cutting elements 25 or 35 without disturbing the mounting of the frame itself or any oi' the other structural parts.

Inlet end outlet connections between the source of heat supply and cutting elements 25 and 35 may be any simple form of piping. Such piping may include the inlet pipe 40 supplying heated fluid to cutting elements 25 and 35, and an outlet pipe 4I acting as a return. The mounting carrying the ends of these tubes for heated ele- -ments 25 and -35 in open slots 31 and the connections between these mountings and the inlet and outlet pipes 40 and 4| are shown in detail in Figs. 5, 6 and 7, and will now be described.

Fig. 8 illustrates diagrammatically the manner in which heating elements of the diameter herein disclosed and used in my'machine will tend to bow or flex when hot and the weight of the ice is carried thereby. In Fig. 8, a cake of ice is shown in dotted lines and partially passed beyond the cutting elem'ent'to illustrate how the cutting element will tend to bow during the cutting action. The mounting herein disclosed allows the cutting elements to flex in the manner illustrated without permitting a permanent distortion to occur. These cutting elements are in the form of a thin walled tube of small diameter through which steam (superheated if desired) is passed. The thin walled tube willallow rapid heat transfer s and amore eiilcient and rapid cutting action.

The small diameter will eiTect a very definite cut with minimum loss of material. Each tube is fixedly secured within a bushing 42 lying in a slot 31 and having an enlarged head 43 at the outer end to form a shoulder at'this end which cooperates` with av washer 44 at the slot to confine a spring 45 therebetween. 'I'he tube continues beyond bushing 42 and is coiled at 45, the end of the tube being fixedly secured within a sleeve 4I that forms a part of the detachable con nection 45 in the form of a nut 43 threaded upon one end of a nipple 56.` Nipple idias the other end threaded into either inlet pipe or outlet pipe 4I, as the case may be. In other words, connection 48 maybe the same for the end of a tube whether the end connects with inlet 46 or with outlet 4I.

A resilient mounting formed by bushings 42 and springs allows such freedom at the end of each tube by the tilting of the bushings 42 in slots 31. as illustrated in Fig. 8, when the tube is flexed, that no permanent distortion will result and the tube will be readily permitted to return to its original position.

Cutting elements I5 are mountedv substantially in the same manner as cutting elements 25 and r35. Vertical members I6 of frame I2 have their inside legs I6' slotted, as indicated at 52 in Fig. 1,1,t0` receive the tube mountings. Slots 52 are similar to slots 3'I in frame 36. Inlet and outlet pipes 53 and 54 are similar to inlet and outlet pipes 40 and 4 I. The mountings likewise comprise bushings 42 having heads 43 thereon between which and legs I6' springs 45 are disposed so as to permit cutting elements I5 to flex against the action of springs 45 and thereby permit their return to normal position without causing a permanent distortion. The ends of cutting elements I5 extend through bushings 42 and are coiled at 46, the extremities thereof being similarly secured in a sleeve 41, as illustrated in Fig. 6, which is detachably connected by a connection 48 to either the inlet or outlet pipes 53 and 54 as the case may be. Any suitable source of heat supply may be provided. v

\ For the purpose of illustration only, a steam generator is disclosed inFig. 2. Inlet connections 53 having cutting elements I5 are connected to a pipe 6I leading to generator 60. Inletv connections 40 of cutting elements 25 and 35 are connected to a pipe 62. The return connections 4I that extend about frame 36 have cutting'elements 25 and 35 connected at 63 to a pipe 64. Returnl connections 54'on opposite sides of frame I2 having cutting elements I5 are connected to a pipe 65. Pipes 64 and 65 are connected to a common return pipe 66 leading to generator 60. It will be understood that inlet connections 6I and 62 may receive their heat supply from any suitable source and that return connection 66 may be likewise connected. Generator 60 is merely disclosed for the purpose of illustration'.

It will be understood that the novel type of mounting exemplified by the springs 45 and the bushings 42 removably resting in open slots, together with the coiled ends 46, may be advantageously used in connection with electrically .k

heated cutting elements, and consequently, in so far as these features are concerned, the disclosure is not to be limited to a uid heating medium.

Any of the cutting elements I5, 25 and 35 may be readily replaced, if desired, bydetachably connecting the ends thereof at 48 and lifting the bushings 42 out of slots 31 or. 52. elements are to be heated by steam orother suitable fluid, they may be tubes of exceptionally small` diameter which is desirable in order to reduce the heating iluid and eiicient heat distribution.

For example, in order to obtain a cutting element of increased strength and cutting capacity but the cutting element, attachedftoy ting elements 25are longitu If these cutting l so as to eliminate excessive W te- 'l very rapid cutting action in `orde It will also be understood that the cutting ele-L ments may be in different shapes cross sectionally.- u l V y A;

A minutes bythe machine disclos cut whereby a minimum cuttiV vided, a substantially circul what flattened in one direct in Fig. 14.

the cutting area covered by the; I By arranging the inlet and ,s parallel arrangement about h" fra'v grid, say pipes 53 and 54 on 'Mch/ id` and pipes 46 and 4I about t 'fra e, of the cutting elements may e nected along one side to theln nections. For example, as illustrated i the uppermost cutting elementi right-hand end connected shown in Fig. 1l, while its connected to the inlet pipe 53 of frame I2 so that the flow o t will be'frorn left to right asV The second uppermost cutti have its right-hand end conn ted 53, as shown in Fig. 1l, and connected to the outlet pipe,.,5 side of frame I2, so that th` `lio medium vwill be from right tofjl arrow. This method of connect the cutting elements I5 witlfrfe and outlet connections 53 anfd,54 of frame I2 may be continue elementsk whereby the final the heating medium owing with respect to adjacent cuttin sequently,`if there is any tenden het.

tion, being hotter than theleI outlet connection, a uniform"lis rbu will be obtained over the enti ,rea all the cutting elements of oiifehgriz'i,` Q the mock of ice win not be cut at to result in unevenI cutting. 'T attachingy the ends n of cuttin y will be noted in FigsA to. 7, inclusi By referring to Fig.'13, it will 'be observed that.. side anges 20 of apro higher than ribs H guide the ice as it t slopingapron I Il.

.nsefzfleiem snow hot to slab* the ice horizontally, 1l dotted lines in Fig. 2. WherrfthelentJ ice has been slabbed, it will sli'difrdm end 2| of apron Il) on to the seco cutting elements 25, it being respect to apron I0. Thew force the'cutting elements 2.5 e the ice `'will drop downwardly-upc cutting elements 35. Thegfsarne, actioni will occur in ,ordertol produc, drop intoareceptacle 65.

Thearrangementdisclose pe heated cutting elements of ,mintmumw mum capacity. I have foun cake of ice may bey complete pound cake of ice by a machine having electrically heated resist-ance wires as the cutting elements. Moreover, the three sets of cutting elements 4are arranged with respect to apron IU to assure self movement of the cake of ice throughout the machine after it has been placed upon the forward end of apron l0.

Without further elaboration, the foregoing will sol fully explain the gist of my invention that others may, by applying current knowledge, readily adopt the same for use under varying conditions of service, without eliminating certain features, which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and securedto me by the following claims.

I claim:

1. In an ice cutting machine, the combination of a frame, a table carried by said frame and arranged for feeding a cake of ice forwardly, a grid interposed in the normal path of travel of such cake of ice and substantially perpendicular to such path, said grid comprising a plurality of parallel pipes for conducting a heating medium therethrough to divide such cake into a set of superimposed slabs, a second .grid 'including a plurality of parallel pipes for conducting a heating medium therethrough and` arranged to receive said set of slabs and convert the same into a plurality of ice cubes, each of said grids including a frame, and means for resiliently supporting the respective parallel pipes of the grid by the frame thereof to compensate for expansion caused by heating and for bowing caused by the weight or pressure of the ice against the grids.

2. In an ice cutting machine, the combination of a frame, a table carried by said frame and arconnections between said supply means and said pipes.

3. In an ice cutting machine, the combination of a frame, a table carried by said frame and arranged for feeding a cake of ice forwardly, a grid interposed inthe normal path of travel of such cake of ice and substantially perpendicular to such path, said grid comprising a plurality of parallel pipes for conducting a heating medium therethrough to divide such cake into a set of superimposed slabs, a second grid including a plurality of parallel pipes for conducting a heatin'g medium therethrough and arranged to receive said set of slabs and convert the same into a plurality of ice cubes, means for supplying a heating medium to said pipes, resilient connections between said supply means and said pipes, each of said grids including a frame, and means for resiliently supporting the respective parallel pipes of the grid by the frame thereof to compensate for expansion caused by heating and for bowingl caused by the weight or pressure of the ice against the grids.

4. In an ice cubing machine, the combination of a frame, a table carried by said frame and arranged for feeding a cake of ice forwardly, a

grid interposed in the path of travel of such cake of ice, said grid comprising a plurality of parallel pipes for conducting a heating medium therethrough, a second grid including a plurality of parallel pipes for conducting a heating medium therethrough, the pipes of both said grids being arranged to perform cutting operations converting the cake of ice into a plurality of cubes, each of said grids including a frame, and resilient means for mounting the respective pipes of each grid upon the frame thereof, said resilient means including springs at opposite ends of each pipe to compensate for any tendency of said pipes to expand or bow. s

5. In an ice cubing machine, the combination of a table for feeding a cake of ice forwardly, a grid interposed in the normal path of travel of such cake of ice and substantially perpendicular to such path, said grid comprising a plurality of parallel pipes for conducting ay heating medium therethrough, a second grid including a plurality of parallel pipes for conducting a heating medium therethrough, connections for supplying a heating medium to said pipes, the pipes of said grids being arranged to perform consecutive cutting operations converting the cake of ice into a plurality of cubes, each of said grids including a frame, mounting means for resiliently suspending the respective parallel pipes of each grid upon the frame thereof, and resilient means in said supply connections to compensate at said supply connections for any movement at said mounting means.

6. In an ice cubing machine, the combination of a frame, a plurality of pipes for conducting a heating medium therethrough to convert a cake of ice into a plurality of cubes, means for yieldably supporting said pipes upon said frame Whereby they are held under tension in their operating relation upon said frame, and structure for supplying a heating medium to said pipes, said structure including resilient means yieldable to any movement of said pipes at their said yieldable supporting means.

7. In an ice cubing machine, the combination of a plurality of pipes to which a cake of ice is fed for a cutting operation, a frame, means for yieldably supporting said pipes under tension `upon said frame, inlet and outlet headers adjacent said frame for supplying a heating medium to said pipes, and yieldable means so connecting said inlet and outlet headers to said pipes that the heating medium may now in one direction through alternate pipes and in the opposite direction through' the rest of the pipes and thereby provide substantially the same cutting heat at said pipes relative to a'crosswise dimension of the cake of ice whereby to secure uniform cutting without any tendency for the cake to twist and crack by too rapid cutting at one side.

8. In an ice cubing machine, the combination of means for feeding a cake of ice forwardly, a grid comprising a plurality of parallel pipes to which' such cake of ice is fed for a cutting operation, a second grid comprising a pluralityof parallel pipes to which the ice is fed for further cutting, connections for supplying a heating medium to said pipes, said connections feeding the heating medium to said pipes of each grid so that they act as a whole to apply substantially uniform heat crosswise of, the cake to prevent thereby any tendency of the cake to shift sidewise during the cutting operation, and supporting means for said pipes acting to keep said pipes substantially uniformly spaced from each other at all times whereby uniform cutting may be obtained.

9. In an ice cubing machine, the combination of means for feeding a cake of ice forwardly, a plurality of grids each containing a plurality of pipes to which such cake of `ice is fed for a cutting operation, means for so providing a substantially uniform heat to said pipes of each grid that they acting as a whole will apply substantially uniform heat to the cake crosswise of the grid to prevent thereby any tendency of the cake to shift sidewise during the cutting operation, and means tending to keep said pipes substantially equally spaced lengthwise of each other by compensating for expansion and bowing of said heated pipes.

l0. In an ice cubing machine, the combination of a grid comprising a plurality of pipes for cutting a cake of ice, means for so supplying a substantially uniform heat to said Jpipes that they as a unit will apply substantially uniform heat to the cake crosswise of the grid to prevent thereby any tendency of the cake to shift sidewise during the cutting operation.

11. In an ice cubing machine, the combination of a grid comprising'a plurality of. pipes for cutting a cake of ice fed thereto, means for so supplying a substantially uniform heat to said pipes that they as a unit will apply substantially uniform heat to the cake crosswise of the said pipes to prevent thereby any tendency of the cake to shift sidewise during the cutting operation, and supporting means for said pipes acting to keep said pipes spaced a predetermined distance from each other whereby uniform cutting may be obtained.

12. In an ice cubing machine, the combination of a grid comprising a plurality of pipes for cutting a cake of ice fed thereto, connections for supplying a heating medium to said pipes, said connections including a pair of. inlet headers positioned on opposite sides of said grid receiving the ends of said pipes, and means for connecting one of said headers on each side to alternate pipes, and means for connecting the other header to the rest of the pipes whereby to cause the heating medium to flow in opposite directions in adjacent pipes and provide thereby a substantially uniform cutting action crosswise of the grid to prevent any tendency of the cake of ice being fed to the grid to shift sidewise during the cutting operation.

13. In an ice cubing machine, the combination of a grid comprising a frame and a plurality of pipes for cutting a cake of ice fed thereto, connections for supplying a heating medium to said pipes, said connections including inlet and outlet headers, there being looped portions between said inlet and outlet headers and the ends of said pipes, said looped portions being yieldable to movement caused by expansion or tendency of said pipes to bow during the cutting operation, and yieldable means for supporting said pipes upon said frame to compensate for said expansion or tendency of said pipes to bow.

14. In an ice Vcubing machine, the combination of a grid comprising a plurality of pipes for cutting a cake of ice fed thereto, connections for supplying a heating medium to` said pipes, said connections including inlet and outlet headers positioned on opposite sides of said grid for connecting to the ends of said pipes, and means on each side for connecting said inlet header to alternate pipes and said outlet header to the rest dium to flow in opposite directions in adjacent pipes and provide thereby a substantially uniform cutting action crosswise of. said grid as the cake is fed thereto, saidl means including a yieldable portion adapted tol compensate for movement of said pipes.

15. In an ice cubing machine, the combination of a grid comprising a plurality of pipes for cutting a cake of ice fed thereto, connections for supplying a heating medium to said pipes, a frame, means for carrying said pipes upon said frame comprising spring means at the ends of each of said pipes for holding the latter under tension upon said frame whereby to compensate for expansion due to heat and for any tendency of said pipes to bend when subjected to the pressure of the ice being cut thereby, said pipes thereby being held substantially uniformly spaced during the cutting operation.

16. In an ice cubing machine, the combination of a grid comprising a plurality of pipes for cutting a cake of ice fed thereto, connections for supplying a heating medium to said pipes, a frame, there being means upon said frame for removably supporting said pipes, and means along the sides of said frame and at the ends of said pipes for holding said pipes under tension upon said grid whereby to keep said pipes substantially parallel to each other in a predetermined spaced relation.

17. In an ice cubing machine, the combination of a grid comprising a plurality of parallel pipes for cutting a cake of ice fed thereto, connections for supplying a heating medium to said pipes, a frame, there being means upon said frame for removably supporting said pipes, means along the sides of said frame and at the ends of said heated pipes for holding said pipes under tension upon said grid whereby to keep said pipes substantially parallel to each other in a predetermined spaced relation, said supply connections including means adapted to compensate for any movement of said heated pipes.

18. In an ice cutting machine, a grid unit comprising a frame defining an opening through which ice to be cut may be moved, two sets of parallel pipes, the pipes of one set being arranged at right angles to the pipes of the other set for conducting a heating medium therethrough, means for carrying said pipes upon said frame over said opening, an inlet header and anvoutlet header, each being arranged substantially in four communicating sections, there being a section. on each side of said frame for connection with the ends of certain of the pipes, means for connecting both said inlet and outlet headers in a predetermined order to said pipe ends, a source of supply for the heating medium, and means for connecting said source of supply substantially at the corners of said sections of said inlet header Where they are joined. y

19. In an ice cutting machine, a grid unit comprising a. frame having four sides which define a substantially rectangular opening through which ice adapted to be cut is moved, two sets of parallel pipes, the pipes of one set being arranged substantially over said opening at right angles to the pipes of the other set for conducting a heating medium therethrough, means for supporting the opposite ends of each set of parallel pipes upon opposite sides of said frame, outlet and inlet headers for said pipes, said inlet'header extending about the four sides of said frame, a source of supply for the heating medium, and means for' of the pipes whereby to cause the heating meconnecting said source of supply to said inlet header substantially at the four 'corners of said frame.

20. In an ice cutting machine. a grid unit comprising two sets of parallel pipes, the pipes of one set being arranged at right angles to the pipes of the other set, a. frame for supporting said pipes substantially at their ends, a pair of inlet header sections for the ends of the pipes of each set, and a, connection for supplying a heating medium to each header section from each end thereof.

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