US2671655A - Shuffle muffle heat treating furnace - Google Patents

Description

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P. C. OSTERMAN ET AL SHUFFLE MUFFLE HEAT TREATING FURNACE o o 0 NI 0 MI. Q .9. & R Q

March 9, 1954 Filed Jan. 10, 1951 Patented Mar. 9, 1954 SHUFFLE MUFFLE HEAT TREATING FURNACE Philip C. Osterman, Elizabeth, and Frederick W. Hombruch, Roselle Park, N. J., assignors to American Gas Furnace Company, Elizabeth, N. 1., a corporation of New Jersey Application January 10, 1951, Serial No. 205,272

' 3 Claims. I l

The present invention relates to furnaces for heat treating metals and more particularly to furnaces wherein the work may be caused to move through the heating zone while maintained enveloped in a controlled atmosphere.

A primary aim of the invention is the construction of a furnace with means and mechanism arranged automatically to feed the work progressively from the entrance end thereof through the heating regions to the delivery end 'while simul- Q which the supporting arms extend are maintaneously maintaining the work somewhat in a state of agitation and all the while surrounded with a protective gaseous medium suited to the nature of the process or so that oxidation or dis coloration of the work will not take place.

A further aim of the invention is the construction of a combined muflie and work support adapted to be so actuated from the exterior of the furnace as to effect progressive movement of the work therealong.

Stillanother objective of the invention is to support a movable muflle in a substantially frictionless manner at a plurality of regions along the path traveled by the work to the end of relieving the load on the muilie actuating meansand of prolonging the life of the several component parts.

Th invention further aims to construct a furnace with a movable muliie supported in such manner that the heating chamber of the furnace is maintained closed to the ingresslon of external gases, e. g. atmosphere, that ordinarily would react unfavorably on the work or would tend to lowerthe temperature, and likewise closed to escape therefrom of furnace gases whereby to attain increased furnace efllciency.

Another main objective of the invention is to render available an improved work feeding means that is relatively quiet in operation, which may be disposed at a reasonable distance from the heated portion of the furnace so as to remain uneilected by the heat thereof. that may be constructed of relatively few parts easily to fabricate and assemble, and which may employ for as its primary power, compressed air, at pressures commonly available in industrial plants.

In carrying forward the aims of this invention it is proposed to construct a furnace with a reciprocable muille similar in some respects to the muflle shown in the patent to A. W. Machlet #2,021,072, but unlike the patent in that, among improved features, the mulile of the present invention is supported at its underside by a plurality of upstanding pivoted arms, the journals of which are disposed below the amine and prefertained fully closed. Th journals themselves are by the manner of mounting, constantly cooled by the ambient air and are readily accessible for water cooling if necessary.

The entrance end of the mufile is arranged to extend forwardly out of the heating chamber and provided with a flame curtain across its entrance end through which the work to be treated passes on its way to the heated regions within the furnace. The delivery end of the muflie is equipped with a down spout through which the work may fall by gravity into a quench tank. In the preferred embodiment of the invention, the mufile and its flame curtain, loading tray and down spout are arranged to be reciprocated from its forward end by pneumatic piston and cylinder means whose directions of stroke and the frequencies thereof are controlled by a cam actuated reversing. valve, the latter being powered by a small electric motor geared to provide the reciprocatory speed desired.

Other objects and advantages will be in part indicated in the following description and in partapprehend the underlying features hereof that they may embody the s e in the various ways contemplated by this in 'ention, drawings depicting a preferred typicahconstruction have been annexed as a part of this disclosure and, in such drawings, like characters), of reference denote corresponding parts throughout all the views, of which: 4%

Figure 1 of the drawings illustrates, partly in section, a heat treatingfffurnace embodying the invention.

Fig. 2 is a plan view, partly in section, of

Fig. 3 is a front end elevation of the furnace. Fig. 4 is a rear view of the furnace, shown partly in section in two planes. I Fig. 5 is an enlarged plan view of an air motor, valve and valve actuating means, with portions broken away to clarify the principles envolved.

Figs. 6 and 7 are vertical sectional views of one of the pairs of muflle supports and its mounting. Referring more particularly to Figs. 1-4, the furnace illustrated comprises a main frame ID, that supports an elongated generally rectangular and hollow furnace ii, the walls of which are 3 constructed of the usual iirebrick and insulating materials as will be understood. A series of burners II are positioned at suitable intervals in the side walls and by means of which the hollow interior of the furnace may be heated to the temperature desired to process the work.

A work supporting and conveying muflie II is disposed within and substantially the full length of the combustion chamber ll of the furnace. The forward end of the tube like muilie extends through the front end wall of the furnace and is partially cut away to form a work receiving tray lie. The delivery end of the tunnel is closed but provided with a discharge tube ll leading into a quench tank "a. customarily the lower end ll of the discharge tube is submerged in the quench liquid, and to prevent upward splash of the quench medium incident to the falling of the workpieces thereinto the tube is provided with fluid cascade mechanism indicated at H. Line It indicates a gas line by which a gaseous medium may be introduced into the muflle for protecting the work, treating, or flushing purposes. Excess gases escaping from the entrance end of the tunnel are burned at the flame curtain It provided. A fume exhausting line Ila connects with the interior of the chute II and leads to a burner lib. Combustion air, and fuel if desired, is supplied to the burner lib by a line lic. By this construction fumes rising from the quench medium are drawn of! and burned and hence do not enter the muine l3.

As illustrated in Figs. 3, 4, and 6, the muiile l! is hollow and generally rectangular in crosssection. Its underside rests upon spaced supports 2|, II, and 2!. Supports II and Il are in pairs and have their upper ends curved as at 24, with the center of the radius at the axis of the shafts newness 1 3|. The pair of supports ll, at the entrance end of the muiiie, are also notched at their upper ends to interlock with a rib formed upon the underside of the muiile ll. The lower ends of the supports 2| are secured to a rock shaft 26 iournaled in bearing brackets 21 mounted securely to the main frame ll. The outer end of the rock shaft It carries a lever 20 that has a pivotal connection with a long link 2!. Link 28 extends under the furnace and is pivotally connected with each of rock shafts 30 through the medium of similar levers ll.

Each of the rock shafts ll, in the instant disclosure, there being flve in all, are journaled in bearing brackets 32. The bearing brackets are each constructed to cradle a pair of supports Ill, and each has closed side and end walls 33 and 34 respectively, with their upper margins flanged as at ll. The flange OI extends completely around the journal bracket and is securely fastened to the underside of the furnace structure ll. Within the margins of the flange suitable openings a are provided in the lower wall of the furnace through which the levers 20 project, the lower end of each lever being keyed or otherwise secured to an associated rock shaft 3.. Numeral 31 indicates bearing elements in the brackets in which each rock shaft may oscillate with case. If, due to the maintenance of relatively high furnace temperatures, the rock shafts heat up unduly, they may be cooled by passing a cooling agent, e. g. water, through their interiors which are drilled out as at '38 for that purpose.

In accordance with this invention the entrance end of the mulile projects through an opening 40 in the furnace and overlays the top ll of supplementary frame structure 42. The frame 42 22 whichinthisinstanceisintheformofa pair of anti-friction rollers.

The extreme forward end of the mullle is pivotally connected to a short link member 48 whichinturnisconnectedtoonearmllofa.

naledinabearingblocklisecurelyfastued cross brace ll. The other arm ll of the 4| is relatively long and massive and is connected with a short link ll that in otally connects with the upper end of a rod I2. The piston rod projects from the upper end of an air motor 53 that is mounted on the shelf 44.

The motor It includes a cylinder member 84, and a cooperating piston II that is fastened to the piston rod 52. Above and below the piston, air chambers It and I! respectively are formed in the cylinder, each chamber being in communication with an air line II or 5! leading to a control valve ill. Inside the cylinder at the undersideof the piston a cushion I is installed to absorb the shock and noise as the piston reaches that end of its stroke.

The control valve BI, is of the reversing type having a valve piston member 02 reciprocably mounted therein. The piston is formed with two enlarged valve portions I and M spaced from one another so as to divide the valve cylinder into three chambers. The center chamber may be regarded as a pressure chamber which constantly communicates with a compressed air line 65, and alternately with cylinder lines 58 and is. The end chambers constantly communicate with exhaust lines 86 and i1, and each in alternation with the cylinder lines it and it as the valve piston is shifted from one of its extreme positions in the cylinder I to its other extreme position. The core portion "a of the valve piston is arranged to extend through one end of the valve body and normally is urged by a compression spring I, against the face of a hammer cam ll. The cam is in the form of a spiral having an ascending portion "a, an abrupt descending portion llb, and is mounted upon the output shaft of a power transmission herein illustrated as geared motor ll, though other forms of drive, such as a variable speed drive, may be employed.

When the motor switch (not shown) is closed, the hammer cam II is caused to revolve whereby the piston 82 is moved relatively slowly'to the ill:

' left (Figs. 3 and 5) and then quickly to the right,

in alternation and continuously. When the valve piston is in the position shown in Fig. 5, compressed air from line I is directed through the valve to line I! and reacts against the underside of the motor piston and the latter moves upwardly. Through the linkage and connections II, II, ll, 48, 41, and ll, the muiile is withdrawn from the furnace a limited distance. When the air valve is shifted to the right in Fig. 5, pressure air is directed to the upper side of the motor piston and the latter moves downwardly. Through the linkages mentioned, the muflle is thereby caused to move into the furnace a limited distance. When the reversing valve is in either of its effective positions, air exhausted from the forward side of the motor piston is expelled through one of the end chambers of the valve and the associated exhaust line I or 81, as will be understood.

In the positlon of the'parts illustrated in Figs.

, bearing ends 24 are thus caused to move in 1 and 3, the muille It has been withdrawn and is at rest against the stop 15, the piston 55 ofthe air motor is in its upper limited position and the valve is still moving to the left and continues so to move until the line 59 leading to the bottom of the air cylinder is wide open. As soon as the hammer cam "revolves sufficiently to let the valve piston move past or down the steep decline b, the spring 68 shifts the valve quickly to the right. This movementopens the lower end of the cylinder to exhaust and the upper end quickly to pressure from the line 55. Through the linkforward into the furnace rather quickly, and the workpieces thereon are also carried forward, the

' movement in'the forward direction being assisted by the weight of the arm 50, piston rod 52 and the piston 55. As the mufile moves forward, the

not positively restrained, they are caused to slide a short distance further along the muflle when the latter is abruptly stopped by reason of the ages referred to, the muiile l3 iscaused to move workpieces gather momentum and as they are son and partake of a rolling motion with the muille without actually shifting, hence there is no wear on the arms or muflle and the latter can be reciprocated with a minimum effort. It will be further observed that with this character of support, the muffle may be anchored at one end,

preferably the loading end, as by the lever 41 be mounted upon the quench tank lie or be a part of a bracket secured to the main frame it.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily I adapt it for various utilizations by retaining one muffle. The workpieces thereon, which previously had slid forward hold their new positions and move back with the muiile. As the muflle is brought to a stop against the abutment 15, the workpieces, which have not gathered sumcient momentum to slide, retain their positions on and relative to the muiiie floor. The pafts are so related and coordinated that on completion of the retracting stroke of the muflie, as determined by the stop 15, the valve has still some distance to travel before line 59 is fully opened. In consequence of this relation the piston of the air motor, and also the muilie, never attain the speed on the retracting stroke that they attain on the forward stroke, with the result that the workpieces 'slide forward at the end of the forward stroke and hold their positions on the muiiie at the end of the retracting stroke. The repeated cyclic movement of the muffle thus causes the work to advance step-by-step through the muiile. With the mufiie heated to a given temperature the rate of progress of the work through the muiiie may be controlled by varying the stroke imparted to the muiile and the rapidity thereof with due regard to the mass of the individual pieces being processed. On a run of workpieces round by 2 inches long, ten valve cycles per minute gave a desirable feeding rate through the muflie.

As indicated in Fig. l, outward movement of the muiile is limitediby the adjustable screw stop 15, and the inward movement of the muflle is limited by the motor piston 55 engaging the shock absorber 6 I the former providing a simple means for varying the stroke of reciprocation of the muflle, and the latter a silencer at the end of the forward stroke.

As the. muiile is reciprocated, the rib 25 on the underside thereof being interlocked with rocker arms 2|, causes the arms 2| to oscillate in synchronism. The arms 2| are, as hereinabove explained, operatively connected with each of the pairs of rocker arms 20, whereby the latter are also power operated. The upper curved load m.

or more of the features that, from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims:

Having thus revealed this invention, we claim as new and desire to secure the following combinations and elements, or equivalents thereof,

by Letters Patent of the United States:

1. A work treating machine combining a furnace having an elongated heating chamber therein defined by integrallyconnected upper, lower, side and end walls with a work receiving opening in one of the end walls, an elongated work treating muffle mounted for reciprocation in a linear path within the heating chamber, said muflle having a work-entrance end projecting through the said opening in one of the end walls, means for supporting the muflle for reciprocation within the heating chamber of the furnace comprising a plurality of longitudinally spaced muffle-supporting arm members pivotally connected to the exterior surface of the lower wall of the furnace and projecting upwardly through correspondingly positioned openings provided in the said lower wall, said arm members having end portions extending into the furnace chamber in abutting relation with the muiile for supporting the latter, each of said arm members havingan end face upon which the muflie rests for supporting the weight of the muflle shaped in the form of a segment of a cylinder having a. radius equal to the radial length of the latory'movement to the muffle supporting arm members thereby to cause their respective segmental end faces to move through a circular distance equal to the linear distance the muilie is reciprocated so that irrespective of changes in muille length incident to changes in temperature and the resulting changes in the positions of contact with the end faces of said arm members 7 the reciprocating forces are applied to the muflle at a pluralit of points lengthwise thereof, said linkage means including a two-armed lever movable about a fixed pivot and having one of its arms connected with the mume and its other arm connected with said first named muifle-supporting arms, said two arms being relatively proportioned to efiect movement of the mumesupporting arms synchronously with the linear reciprocations of the muflie.

2. The combination of claim 1 in which said arm members spaced longitudinally of the iurnace are arranged in pairs and each pair being secured on a common rock-shaft and in which the said other arm of the said two-armed lever operatively connects with the rock-shaft of each pair of arms for oscillating the arms of each pair in unison.

3. The combination of claim. 1 in which the pivoted ends of the supporting arms are journaled in flanged housings, portions 01 which surround and form closures for the corresponding armopenings in the lower wall of the furnace to exclude surrounding air from the heating chamber of the furnace.

PHILIP C. OS'I'ERMAN. FREDERICK W. HORN'BRUCH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,611,098 Borner Dec. 14, 1926 1,695,950 Carpenter Dec. 18, 1928 2,021,072 Machlet Nov. 12, 1935 2,331,419 Patterson Oct. 12, 1943 2,365,978 Strain Dec. 26, 1944 2,447,393 Campion, Sr. Aug. 17, 1948 2,473,193 Campion June 14, 1949 2,600,401 Gilbert June 17, 1952 FOREIGN PATENTS Number Country Date 117,849 Australia Dec. 16, 1942

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