US2741469A - Bit heating furnace - Google Patents

Description

April 10, 1956 J. WALLERIUS BIT HEATING FURNACE Q 5 Sheets-Sheet 1 Filed Jan. 12. 1952 INVENTOR JOHN WALLERIUS QR ww ATT'YS 5 Sheets-Sheet 2 J. WALLERIUS BIT HEATING FURNACE April 10, 1956 Filed Jan. 12, 1952 INVENTOR JOHN WALLERIUS ATT YS April 10, 1956 J. WALLERIUS BIT HEATING FURNACE 5 Sheets-Sheet 3 Filed Jan. 12, 1952 INVENTOR JOHN WALLERIUS BY 4 W 9 0M ATT'YS April 10, 1956 J. WALLERIUS BIT HEATING FURNACE Filed Jan.

5 Sheets-Sheet 4 R O T N E V N JOHN WALLERIUS April 10, 1956 J. WALLERlUS 2,741,469

BIT HEATING FURNACE Filed Jan. 12, 1952 5 Sheets-Sheet 5 INVENTOR JOHN WALLERIUS dclwi ATT'YS United States err HEATING FURNACE John Wallerius, Glen Ellyn, Ill., assignor to Sunbeam Corporation, Chicago, 111., a corporatien of filinois Application January 12, B52, Serial No. 266,125

4 Claims. (Cl. 263-2) The present invention relates to heat treating apparatus and more particularly to a bit heating furnace for heating drilling bits extensively used in drilling blast holes for various mining operations and the like.

In numerous mining and other operations it is necessary to drill blast holes into which the necessary explosive is placed for subsequent detonation to break away the stone, ore, or other material being drilled. For this purpose, extensive use is made of bits which are designed to perform four important functions; namely, (1) penetrating (2) crushing (3) reaming and (4) mixing. The penetrating action or function is accomplished by the cutting edge or point of the drill while the crushing function is accomplished by the face of the drill. The reaming function is obtained by the circumference or outer edge of the bit while the mixing function is accomplishedby longitudinally extending slots on either side of the drill bit throughwhich water and cuttings must pass when the bit is moved up and down the drill hole.

In difficult drilling operations these bits wear very rapidly particularly in hard material, and in manyapplications a bit is only run about an hour before it-vis changed. For the purpose of reconditioning these bitsfor further use generally termed bit dressing or bit sharpening, elaborate machinery has been developed which is much more effective and accurate than dressing the bits by hand. Machine dressed bits are of uniform shape with every bit being dressed in exactly the same manner. Hand dressed bits are, of course, less uniform and often result, if not properly dressed, in sticking of the tools during the drilling operation. A conventional bit dresser may comprise a horizontal arm and a radial hammer both adapted tostrike the bit alternately at as high as 500 blows a minute. This dressing operation occurs when the bit has been heated to a desired temperature generally over 2000 F. Prior to the present invention, it was necessary to heat the bits before dressing in a suitable forge and numerous difficulties were encountered in such prior arrangements. The bits are elongated elements of various diameters depending upon the size of hole to be drilled thereby which holes might vary in diameter from 5 to 12 inches. In prior art arr'angements the end of the bit to be dressed was inserted into a forge heated from the bottom. Because of the slow heating the shape of thebit was sometimes, lost during such heating. Moreover, a tremendous amount of heat was lost from the furnace and additionally the shank of the hits were heated up sufficiently so that during the subsequent bit dressing operation an undesirable upsetting of these shanks occurred. Actually, only about one-sixth of the length of the bit should be heated, but with a slow forging operation a great deal of heat would travel to the parts of the bit which should not be heated. Moreover, in prior art arangements, the forges required were such as to mitigate against portability. It would be desirable to provide a bit heating furnace which was suitable so that it could be readily moved to any locality where its use is desired since obviously such miningoperations in which bit heating furnaces are employed often are moved from time to time and a large fixed installation for machining and heating purposes is unsatisfactory; It is furthermoredesirable to provide a bit heating. furnace which provides uniform heating at high speed. It would furthermore be desirable to provide a bit heating furnace in which the bits may be preheated at lower temperature and then brought up to' the final temperature at high speed. 7

to provide a new and improved heat treating furnace.

It is another object of the present invention to provide an improved bit heating. furnace for heating drill bits prior to a bit dressingt operation in a manner to heat them at high speed, to heat substantially only the portion thereof to be dressed and to accomplish this with a simple, compact and portable unit.

it is a further object of the present invention to provide an improved bit heating furnace having a single high heat chamber in which theheating gases whirl around the bit to heat the same at high speed and a plurality of preheat chambers which utilize waste gases from the high heat chamber.

It is another object of the present invention to provide a portable heat treating furnace for heating the ends of rather elongated objects without efiectively heating the other portions of these objects and without substantial loss of heat around the objects being heated.

Further objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present invention reference may be had tothe accompanying drawings in which,

Fig. l is a somewhat perspective front view of a bit heating furnace embodying the present invention in which hits are being heated in the high heat chamber and in one of the preheating chambers with the other preheating chamber shown in the closed positions and with adapters associated with each heating chamber;

Fig. 2 is a top view of the bit heating furnace of Fig. l ith portions of the top cut away to show the interior construction without any adapters being employed, and with the covers for the heating chambers all in the closed positions;

Fig. 3 is a sectional view on line 3-3 of Fig. 2 assuming that Fig. 2 shows the complete structure;

Fig. 4 is a sectional view taken on line 44 of Fig. 2 again assuming that Fig. 2 shows the complete structure but with the covers removed and with the adapters in position as shown in Fig. 1;

Fig. 5 is a front view adjacent one of the chambers of the furnace of Fig.- l to show the adapter arrangement for adapting the furnace to'heat different size bits;

Fig. 6 is a sectional view taken on line 6-6 of Fig. 5 with a bit to be heated disposed in position and indicated by dotted lines;

Fig. 7 is a perspective view of a representative bit to be heated by the furnace of the present invention; and

Fig. 8 is a view similar to Fig. 6 illustrating another size of adapter for use with the furnace of the present invention.

Briefly the bit heating furnace of the present invention comprises a central heating chamber for heating about a 9 inch length of a bit which may be up to 12 inches in diameter and two side heating chambers which are heated by Waste gases from the central heating chamher for preheating bits prior to their being inserted in the Patented Apr; .10,

Accordingly, it is an object of the present invention central chamber for heating them to temperatmes in excess of ZOOOTF. prior to dressing the same. By means of a plurality of oil burners tangentially disposed with respect to a cylindrical heating chamber, a flame is pro- Referringnow to the drawings there 18 illustrated a bit heating furnace unit generally designated by the reference numeral which is indicated as a completely portable unit including a suitable stand or frame 11 which maybe formed of angle members or the likeforj supporting the bits to be heated by the furnace. The furnace proper generally designated by the reference numeral 12 comprises a front wall 13 and a back wall 14, which front and back walls may be formed of suitable castings of substantially identical configuration. As best shown in Fig. 3 of the drawings, these front and back walls essentially define a large circular central portion with a pair ofsmaller circular diametrically opposed-end portions joined to the central portion. Preferably for manufacturing purposes, the front and back walls-13 and 14 I each comprise a plurality of separate casting sections. .As specifically illustrated, the front wall 13 comprises a top front section 13a, side front sections 13b and 130 respectively, and a bottom front section 13d. Similarly the back wall 14 comprises sections 14a, 14b, 14c and 14d. The adjacent'edges of these sections are preferably provided with suitable flanges 16, through which fastening means such as bolts 17 may extend whereby the sections are united into an effectively integral front wall 13 and rear furnace wall 14. Preferably these front and rear' walls are formed ofcastiron which provides good rigidity and resistance-to-warping when subject to the high temperatures encountered in furnaces of this type.

' To complete the enclosure there is provided in addition to the front and rear walls 13 and 14, a steel sheli 18 which with the front and rear walls completes the furnace housing. Preferably, the front and rear walls 13 and 14 are provided with peripheral flanges 19 which.

overlap the shell 18. Also, the front and rear walls are provided with means for receiving suitable tension bolts such as 20 to hold the walls 13 and 14 and the shell 18 in assembled relationship. The lower casting sections 13d and 14d are provided with integral leg portions 23 for supporting the furnace proper 12 on any suitable surface.

Similarly, the upper casting section 13a of the front wall and the upper casting section 14:: of the rear wall are provided with suitable integral extensions 24 for receiving a suitable beam 25 having an integral extension 25a with a suitable opening 26 therein to permit engagement by suitable crane or the like, thus assuring complete portability of the unit.

The casting sections defining the front wall 13 are provided with suitable openings defined by flanges 26, 27 and 28 respectively, the flange 26 defining the opening to the main or center heating chamber and the flanges 27 and 28 defining the openings to the preheating chambers. In order that these openings may be closed to conserve the heat within'the furnace when the furnace is brought up totemperature or when no bit is being heated, suitable closure members 30, 31 and 32 are provided respectively for the openings at least in part defined by the flanges 26, 27 and 28. As illustrated,rthese closure members are generally circular configuration with a flattened bottom as indicated at 34. Preferably, the covers 30, 31 and 32 comprise a castiron member having a cross section as best shown in Fig. 2 of the drawings which castiron cover members also support a suitable insulating brick generally designated at 35. Preferably, the covers are hinged by suitable hinges 38, fastened 4 to the front wall 13. Each door is preferably also provided witha pair of, handles 39 for ready manipulation thereof.

Any suitable means for supporting the bits to be heated by the furnace 10 of the present invention maybe employed. Since a large portion of the bit will extend outside the furnace during the heating operation, there preferably is provided suitable bit charging equipment which, as illustrated in Fig. .1, may comprise a plurality of bit carriages generally designated at 40, one disposed adjacent each of the openings closed by'covers 30-, 31 and 32. These bit carriages 49 are mounted on suitable anti-friction bearings: forming no part of the present invention which ride on. rails whose longitudinal axis 'is' parallel with the axis of the openings into the furnace l9 controlled by the covers 30, 31 and 32. border to illustrate the operation of the carriages 40, there is shown in Fig. 1 a bit 41 disposed in heating position in the main heating chamber of the furnace 10 and a bit 42 disposed in'heating position in the preheat chamber with which is associated cover 32. These bits are supported on the carriages 40 which are provided with suitable adjustable chain slings 45 to properly position the bits on the carriages in dependence upon the particular size bit involved: As illustrated, the bit carriages are disposed on the frame or support 11 and by using the adjustable chain slings 45, any size bits up to 12 inches may be accommodated. It will be understood that by means of suitable lifting mechanism such as crane or the like, the bits maybe transferred to the bit carriages 40 and from one bit carriage to another where they may be readily moved into and out of the furnace as desired. p

'It will be understood that a very high heat is developed 2 within the furnace 10, approximately-1500 Erin the preheating chambers and 2250-F. in'the high or main heating chamber. Obviously, to prevent heat loss and to protect operators against the high heat, the furnace chambers are provided with suitable insulating and fire resistant linings. As illustrated, 'the furnace' is lined throughout with a layer of insulating brick generally designated by' the reference numeral-49. This insulating brick is provided all around the furnace chamber and is disposed, in

direct contact with the front and rear walls 13 and 14 respectively and the shell 18. In a commercial embodiment builtin accordance with the present invention, the insulating brick provided a wall thickness of 5 /2. inches around the high heat chamber. Additionally, in accordance with the present invention, a molded fire clay tile lining generally designated at 50 is provided for the interior of the furnace for direct engagement with the hot flames and gases of the heating equipment described hereinafter. This fire clay lining is inside the insulating brick 49 and in the commercial embodiment built in accordance with the present invention, this lining comprised a thickness of 4 /2 inches. These thicknesses 'of linings of fire clay 50 and insulating brick 49 provide adequate insulation for temperatures encountered in the furnace as set forth above and assure minimum heat losses and economical furnace operation. The fire clay lining is also provided around each of the openings into the furnace which lining is designated by the reference numeral 51 around each opening into which material to be heated is'inserted. These openings defined by linings 51, are de-' signed so as to" accommodate the maximum size bit generally 12 inches in diameter; As illustrated the fire clay lining 51 around each of the openings is provided with a portion of enlarged diameter generally designated at 52, the purpose of which will become apparent as the following description proceeds. V

As may best be observed by an examination of Figs; 2 and 4, the opening 53 defined by the lining 51 leads directly into the high heat chamber 54 of generally circular configuration defined by the layer of fire clay 50. In accordance with the present invention,-in addition to the opening 53 leading into the chamber 54, there area plurality of additional openings 55, 56, 57, 5'8, 5'9'and leading to the high heat chamber 54. The openings 55 and 56 disposed in diametrically opposed positions lead to the preheat chambers 62 and 63'respectively and are eflfectively, throats or passageways for the gases from the high heat chamber 54' to the low heat chambers 62 and 63'. The openings 57 and 58 are provided to accommo date suitable oil burner units to be described hereinafter and designated by the reference numeral 65 and 66 respectively. The oil burner unit 66 disposed adjacent the lower portion of the high heat chamber 54 is arranged tially with the periphery of the high heat chamber a, s

that the burning oil flame produced by the oil burner causes tangential flow'of gases around the heating chamber 54'and efiectively around the bit such as 41 disposed therein. The oil burning unit 65 on the other hand is tangentially disposed with respect to the upper portion of the more or less circular periphery of the high heat chamber 54. As illustrated, the upper burner 65 is disposed on a horizontal axis so as to reduce to a minimum or entirely eliminate any carbonizing of the upper burner which could occur if the upper burner were disposed with its axis in a vertical direction or some component of its axis in a vertical direction.

The opening 59 on the other hand connects the high heat chamber 54' directly to atmosphere and comprises a control vent which is preferably defined throughout by a fire clay wall including the fire clay wall portion'66. A suitable casting 67 having th'e'opening' 68 defined therein is provided at the outside of the casting adjacent the opening 59. The vent 59 therefore provides an adjustable controlfor the gases escaping to atmosphere, and, hence, a control of the temperature in the preheat chambers 62 and 63, since the more gas. that is'permitted to escape to atmosphere directly from. the high heat chamber 54 through thevent 59; the lower will be the temperatures of the preheat chambers 62 and: 63 which depend entirely for heating thereof upon the gases passing through the passageways 55 and 56. The upper end of the opening 68' may be controlled by a suitable closure member such as apiece of firebn'ck which may completely close the open ing or partially close it as desired.

The other opening 61 into the combustion chamber 54 is to accommodate a. suitable thermocouple, not shown, connected to a suitable indicatin'g pyrometer 7% so that the operator may have an indication of the temperature existing-within the'highh'eat" chamber at all times.

The preheat chambers'62and'63 are of circular cross section defined by the inner fire clay' lining 51' between which and' the shell 18' isthe insulating brick layer. 49. The preheat-chamber 62 is provided with a vent to atmosphere 71 through which the hot gases may escape to atmosphere. This opening. 71 is also completely defined by firebrick including a firebrickl lining 72. A suitable shield 73in the form of a casting or the like is attached to the shell 18 where the opening 71 comes out of the furnace to shield the oil burner 65 from the hot gases escaping. Similarly, the preheat chamber 63 is provided with a vent to atmosphere 74 completely defined by firebrick including the firebrick lining 75. A short casting 76 is attached to the shell 18 adjacent the point where the opening 74 comes outside the furnace wall to define the vent opening.

For the purpose of supporting a suitable compressor unit and oil burning equipment connected to the burners 65 and 66, there preferably is provided at the rear of the furnace a suitable angle iron support 80 as shown in Figs. 2 and 4 of the drawings. It will be understood that suitable piping, oil and air proportioning valves and the like will be provided to supply the burners 65 and 66 with a uniform supply of fuel at constant pressure with manual means for proportioning the air and oil ratio at any desired selected value. Since the details of the oil burner control form no part of the present invention, no disclosure thereof is made herein.

For the purpose ofcausing the furnace 10 to be cap;- able of heating bits of all sizes up to 12 inches, and articularly bits of small diameter Where there would be an annular space around each opening into the furnace and the bit, there are provided in accordance with the present invention suitable adapters as shown in Figs; 4, 5, 6 and 8 of the drawings insertable into the openings such as 53 for the main'he'ating chamber 54, or the openings 83 into the preheat chambers 62, etc. As illustrated, theadapter comprises a ring formed of a suitable alloy generally designated at 35 and a number of pieces of refractory material S6arranged to define a somewhat rectangular central opening 87.- The'pieces' of refractory material 86 are cemented together and to the ring to provide an adapter unit providing a somewhat rectangular opening for closely conforming to the exterior shape of bits such as 41 or 42. In Fig. 7 of the drawings there is illustrated a bit 99 representative of the type of bits for which the present furnace is adapted. It will be understood that the adapter unit shown in Figs. 5 and 6 will accommodate one size of bit and depending upon a particular size of adapter units employed, other bit sizes may be used.

in Fig; 8 of the drawings there is illustrated another adapter unit of different size for accommodating a still smaller bit than that for which Figs. 5 and 6 are designed. These adapter units will be inserted into the opening 53' as is clearly shown in Fig. 6, or the openings 83 to the preheating chambers all of which openings are identical so that the adapters are interchangeable. it will be understood-that in operating the furnace of the present invention, the openings 53 and 523 'Will all be provided with identical adapters since for most efficient heat treatment a single size bit should be heated in all'th ree units at the same time.

In View of the detailed' description' above, the operation" of the present invention willbe readily understood by those skilled ini the art. In heating bits for the dressing operation, the furnace is set in operation with the covers 30', 31' and 32 in a closed position so that the chambers" may be brought up to temperature. if desired,'ouly the cover 30 need be closed and a bit may be placed in each' of the preheat chambers 62 and 63 for preheating; After the bit in one of the preheat chambers is heated-to at least l0tl0 F. (adull red heat); it is placed in the high" heat chamber 5 3 and'another bit is placed into thep'relie'a'tchamber from which the bit has just been removed. Thus one bit is in the high heat chamber and two other bits are disposed in the preheat chambers. The temperature to'which the bits are heated in the preheat chamber may be controlled by controlling the size of the vent 59. When the bit in the high heat chamber is heated to a forging heat somewhere betweenQOOOand 2100 R, it is removed for dressing and'one ofthe bits from the preheat cham-' hers is moved into the high heat' chamber. Bits are maintained in the preheat chambers for aperiod twice as long as they are in the high heat chamber. Depending upon the particular size of the bits to be heated, the appropriate adapter units will be employed whereupon only the portion of the bits desired to be heated will be. heated. Moreover, the hot gases whirling around the bitin the high heat chamber by virtue of the tangential position of the burners 65 and 66 will cause the bit in the high heat chamber to be uniformly heated throughout without any movement thereof. The same is also true of the bits in the preheat chambers since the disposition. of the openings 55 and 56 and the vents 71 and 74 insure such circular motion of the hot gases in the preheat chambers 62 and 63 as well as in the high heat chamber 54.

From the above description, it will be apparent that there has been described a bit heating furnace which is designed for many years of service with a minimum of maintenance. It will, moreover, provide heating at, high production rates. Moreover, this heating will be. even heating throughout with close temperature controh a 7 In a particular furnace built in accordance with the present invention bits up to 12 inches in diameter could be heated with heat distribution along 9 inches of the bits.

While there has been illustrated and described one embodiment of the present invention, it will be understood that numerous changes and modifications will occur to those skilled in the art and it is aimed in the appended claims to cover all such changes and modifications as fall within the tru'e'spiritand scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of, the United States is: v 1 1. A furnace for uniformly heating to a temperature of the order of 2000 F; the end portion only of an elongated work piece, comprising a generally cylindrical high 1 heat chamber, a preheat chamber disposed adjacent said high heat chamber, means for introducing hot gases along a tangent with respect to the circumference of said high heat chamber to produce a rotation of hot gases around the longitudinal axis of said high heat chamber, means defining a first opening for introducing the end of a work piece to be heated along said axis of said high heat chamber, passageway means for-said hot gases from said high heat chamber to said preheat chamber whereby said hot gases from said high heat chamber provide the source of heat for said preheat chamber for preheating a work piece in said preheat chamber to the order of 1500 F., means for controlling the temperature of said preheat chamber. comprising vent means from the upper' part 'of said high heat chamber to atmosphere, and a closure 7 for said first opening to prevent loss of heat from said high heatchamber when no work piece is disposed therein.

2. A furnace for uniformly heating the ends of drilling bitsprior to a bit'dressing operation comprising a hous ing having threespaced circular openings disposed alonga horizontal line across the front thereof, a centrally discylindricalpreheat chambers one disposedon either side 7' of said high heat chamber with their longitudinal axes parallel with said longitudinal axis of said high heat cham' 3. A furnace for heating the ends of drilling bits prior ber, said other two openings each leading to a different, one of said preheat chambers, means for supporting an elongated work piece along the axis of each of said charn-.

'bers in a manner to permit insertion of the'end of said to a bit dressing operation comprising a'housing having three spaced circular openings disposed along a horizontal line across the front thereof, a centrally disposed cylindrical high heat chamber having its longitudinal axis dis:

posed in a horizontal position, said central opening leading to said high heat chamber, a pair of cylindrical preheat chambers one disposed on either side of said high heat chamber with their longitudinal axes parallel with said longitudinal axis of said high heat chambensaid other two openings each leading to a different one of said preheat chambers, means for supporting an elongated work piece along said axis. of each of said chambers in a manner to permit insertion of the end of said work piece into one of said chambers for heating, a source of hot gases, means for introducing said hot gases into .said high heat chamber for producing rotating hot gases around the end of a work piece disposed in said high heat chamber, means for causing hot gases from 'said high heat chamber to enter each of said preheat chambers and swirl around the end of anywork pieces disposed therein, vent means at the 'top of each of said preheat chambers, and means comprising a vent in said high heat chamber for controlling the temperature in said preheat chamber.

4. A furnace for uniformly heating the end vportion only of a drilling bit prior to a bit dressing operation,

opening to said chamber having a diameter sufiiciently large to conform closely to the cross section of the largest bit to be heated in said: chamber, and an adapter insertable in said opening for efiectively reducing the dimension of said opening toconform closely to the cross sec:

tion of a drilling bit of a size smaller than that of said largest bit, said adapter comprising a ring and a plurality of pieces of, refractory material cemented together and to said ring to form a unit, said pieces of refractory material being shaped to define a somewhat rectangular opening.

References Cited in thelfile of this patent UNITED STATES PATENTS 310,402 Fox Ian. 6, 1885 515,261 Sperry Feb. 20, 1894 932,508 Smith Aug. 31, 1909 1,582,036 Grunewald Apr, 27, 1926 1,716,695 Hinderliter June 11, 1929 OTHER REFERENCES Pages 8 and 9, Industrial Furnaces, by W. Trinks, John Wiley; and Sons, Inc., New York, third edition, 1934, volume

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