US2776134A - Heat treating apparatus - Google Patents

Description

Jam 1957 D. E. WINGATE 2,776,134

HEAT TREATING APPARATUS Filed Aug. 10, 1954 3 Sheets-Sheet l g INVENTOR.

ATTO IVF 1957 D. E. WINGATE HEAT TREATING APPARATUS 3 Sheets-Sheet 2 Filed Aug. 10, 1954 INVENTOR. Deg/4L0 E VW/VGATE Jan. 1, 1957 E wlNGATE 2,776,134

HEAT TREATING APPARATUS Filed Aug. 10, 1954 3 Sheets-Sheet s PRO TE C 77VE A TMOSPHERE l OUENCH CHA MBEH COOL lNG CHA M851? INI 'E.\'TOR.

0 9N442) E W/NGATE United States Patent HEAT TREATING APPARATUS Donald E. Wingate, Toledo, Ohio, assignor to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio Application August 10, 1954, Serial No. 448,967

3 Claims. (Cl. 266-4) This invention relates to heat treating apparatus, and more particularly to apparatus in which a load of work, after being heated in a protective atmosphere, can be transferred to a cooling chamber without being removed from the protective atmosphere, and can be cooled in such cooling chamber to normal temperatures in contact with a protective atmosphere, so that the heating chamber can be used for heating a fresh load of work While'the former load of work is being cooled in the cooling chamher.

The principal object of the present invention is to provide simple and compact apparatus which can be employed to conduct a variety of heating and cooling operations as required in heat treatment to impart desired special properties to various metals. More specific obiects and advantages are apparent from the following description, in which reference is had to the accompanying drawings illustrating a preferred embodiment of the present invention.

Figure I of the drawings is a vertical section of the preferred apparatus, taken as indicated by the line I-I of Figure II, longitudinally through the heating chamber.

Figure 11 is a transverse vertical section taken on the line II-II of Figure I.

Figure III is a fragmentary transverse vertical section on a slightly larger scale.

Figure IV is a diagram showing a system for preventing the formation of an explosive mixture of gases during the charging of work into the apparatus.

Figure V is a schematic isometric view showing the unique layout of vestibule, heating chamber, quenching chamber, and cooling chamberof the applicants apparatus.

These specific drawings and the specific description that follows merely disclose and illustrate the invention, and are not intended to impose limitations upon the claims.

A heat treating apparatus embodying the present invention comprises, in combination, a heating chamber having a door, a vestibule outside of the door of the heating chamber, which is adapted to confine a protective atmosphere, and which has a charging door, a second door opening from the vestibule, and a cooling chamber outside of the second door, which is adapted to confine a protective atmosphere, and which is provided with means for circulating such atmosphere in contactwith workin the cooling chamber, whereby a charge may be transferred from the heating chamber to the cooling chamber through the vestibule, and the next charge may be transferred into the heating chamber through the vestibule while the former charge is being cooled.

in the apparatus disclosed in the drawings, a base is provided for supporting the heating chamber 11, which is constructed in a conventional manner and comprises a fire brick lining 12, surrounding insulating walls 13 and a concrete roof 14.

Located on the floor of the heating. chamberll .are rails 15 supporting two parallel series of rollers 16 (only one series of rollers being shown in Figure I). The rollers 16 are adapted to support baskets 17 for holding the work. Each of the baskets 17 rests on a tray that consists of a grating 18, and comprises a floor 19 of heavy wiremesh and corrugated side walls 20.

Gas inlets 21 are provided for admitting a protective atmosphere to the heating chamber.

The means for supplying heat to the heating chamber should be designed to avoid contamination of the atmosphere of the heating chamber, and may consist of an electrical heating element or a series of internally fired heating tubes 22 of the known type, only one of which is illustrated in Figure l. The construction of the heating tubes 22 is such as to confine the products of combustion entirely within the heating tubes so as to prevent the products of combustion from entering the heating chamber.

The heating chamber is provided with a door that comprises a lining 23 of fire brick, an outer face 24 of insulating material and a surrounding metal frame 25. The protective atmosphere that continuously enters the heating chamber through the gas inlets 21 also escapes continuously past the door of the heating chamber. If that door fits too tightly to permit sufi'icient escape of gas, a small passage may be provided for the escape of the protective atmosphere past the door of the heating chamber. In order to permit the door to be raised, a gas-tight hood 26 extends above the door, and a gas inlet pipe 27 is provided for admitting protective atmosphere at a point near the top of the hood 26. Mounted by means of a bracket 28 on top of the hood 26 is an air cylinder 29, which is used to raise the door by means of a lifting rod 30 pivoted to a bracket 31 that is secured to the top of the door frame 25. Arranged inside of the hood 26 is a -shield32 that protects the ceramic material that forms the upper portion of the heating chamber from being abraded during the movement of the door.

A bracket-33 extending from the front of the heating chamber supports an extension of the floor of the heating chamber, and the rails 15 and rollers 16 pass beneath the door frame 25 and extend in front of the heating chamher.

The extended portions of the rails 15 are supported .upon a vertical wall 34 of a quench tank that is filled with a suitable quenching liquid 35. Supported on the opposite wall 36 of the quench tank are a set of rails 37 and rollers 38 aligned with the rails 15 and rollers 16. Erected upon the floor 39 ofthequench tank is a frame work 40. A bracket41 attached to the frame work 40 assists in supporting-the extended portions of the rails 15, and a bracket 42 attached to the opposite side of the frame work 40 assists in supporting the rails 37.

.A metal plate 43 forms an impervious floor beneath the extended portions of the rails 15, and another metal plate 44 forms an impervious floor under the rails 37. A gas-tight hood 45 cooperates with the metal platesj43 and to form an enclosed vestibule lying immediately outside of thedoor of the heating chamber.

As shown in Figure II, the left wall 46 of the quench tank is aligned with the left wall of the hood 45, and the quench tankhas a portion extending to the right, beyond the heating chamber, that is bounded by the right wall '47 of the quench tank. In order to form a seal around the bottom of the vestibule, a plate 48, forming an ex tension of-the right side of the hood 45, extends below the surface of the liquid in the quench tank. Similar hood 45, and is provided with a jacket 53 for a cooling liquid, which jacket covers the bottom and all the vertical walls of the cooling chamber except the wall that separates the cooling chamber from the vestibule. Suitable pipe connections, not shown, are provided for flow of a cooling liquid, such as water, into and out of the various portions of the jacket 53. The jacket 53 also covers the top of the cooling chamber except the central portion thereof on which is located a bearing bracket 54. The bearing bracket 54 supports a vertical shaft 55 on which are mounted a fan 56 and a pulley 57. The pulley 57 is driven by means of a V-belt 58 from a motor 59 that is mounted on the left side of the cooling chamber 51. A protective atmosphere is admitted to the cooling chamber through an inlet 60. The fan 56 is designed to draw the protective gas upward at the center of the cooling chamber 51, and to force the protective gas downward along the walls of the cooling chamber. The protective gas that enters the cooling chamber continuously through the inlet 60 flows from the cooling chamber into the vestibule past a door 61, which separates the cooling chamber from the vestibule.

The door 61 comprises a layer of insulation 62, and a jacket 63 through which a cooling liquid is circulated by means of flexible hose connections not shown. An air cylinder 64 is supported by a bracket 65 on top of a small hood 66 that extends upward at the right side of the cooling chamber 51, and the air cylinder 64 is adapted to raise the door 61 by means of a lifting rod 67 that is pivoted to the top of the door at 68.

Mounted within the frame work 40 is an elevator 69 that includes an upper platform 70 and a lower platform 71. The elevator 69 can be raised or lowered by means of a rod 72 which is pivoted to the elevator at 73. The rod 72 is actuated by means of an air cylinder 74 that is mounted by means of a bracket 75 on top of the hood 45. It will be understood that suitable seals are provided at the points where the rods 72, 30 and 67 enter the respective hoods.

The elevator 69 is provided with adjustable stops 76 that determine the lower most position of the elevator. In order to guide its vertical movement, the elevator is provided with rollers 77 that run in channels in the frame work 40.

The upper platform 70 of the elevator is provided with a pair of tracks 78, which run from right to left in Figure II. A carriage 79 is provided with rollers 80 that run on the tracks 78. Fixed to the top of the carriage 79 are rails 81 supporting two parallel series of rollers 82. As shown in Figure I, when the elevator 69 is in its lower most position and when the carriage 79 is in its extreme right hand position, the rollers 82 are in alignment with the rollers 38 and 16. Extending from the carriage 79 into the cooling chamber 51 is an arm 83 that is connected to a chain 84 that runs on sprockets 85 and 86. The sprocket 86 is rotatably mounted within a small chamber 87 that forms an extension of the cooling chamber 51, and the sprocket 86 can be driven by means of a handle 88 in order to drive the chain 84 so as to move the carriage 79 back and forth between the cooling chamber and the vestibule.

Mounted on the upper platform 70 of the elevator are rails 89 which support two sets of rollers 90. As shown in Figure I, each set of rollers 90 is interrupted at two points by the rails 78, but the tops of the rails 78 are at a lower level than the tops of the rollers 90 so that a basket of work riding on the rollers 90 will clear the rails 78. The rails 78 themselves are interrupted by a cross member 91 on the elevator platform 70, but this cross member also lies below the tops of the rails 78 so that the carriage 79 in riding upon the rails 78 will clear the cross member 91.

The sets of rollers 90 on the upper platform 70 of the elevator are intended to be used in transferring baskets of work into the heating chamber while the carriage 79 is in the cooling chamber 51 and is being used to support baskets of work being cooled in the cooling chamber. In order to permit the rollers to be used in transferring work into the heating chamber, the elevator 69 is raised to a position slightly above the lower most position that is shown in the drawings, so as to bring the rollers 90 into alignment with the rollers 16. Mechanism for locating the elevator 69 so as to position the rollers 90 in alignment with the rollers 16 is shown in Figure III. That mechanism acts to position a stop 92 above a lug 93 on the side of the upper platform 70 of the elevator, so that as the elevator is raised from its lower most position the lug 93 will come against the stop 92 just as the rollers 90 come into alignment with the rollers 16. In order that the stop 92 may be moved into position above the lug 93, and also may be moved out of such position to permit the elevator to be moved to the upper limit of its travel, the stop 92 is carried on a horizontally slidable arm 94 which is supported by rollers 95 mounted on the frame work 40. The arm 94 can be moved horizontally by means of a bell crank 96 that is pivoted to the arm 94 at 97. The bell crank 96 is provided with a hand grip 98 that can be used in positioning the stop 92 to determine whether or not the stop will be in the path of movement of the lug 93.

The lower platform 71 of the elevator is provided with rails 99 carrying two sets of rollers 100, and the rollers 100 are in alignment with the rollers 16 when the elevator 69 is in its upper most position.

As shown in Figure I, a charging door 101 is provided at the front of the hood 45. The charging door is mounted for up and down movement in a guideway 102, and is supported by a chain 103 that runs over a pair of pulleys 104. The opposite end of the chain 103 is attached to a counterweight 105 housed within a shield 106. Attached to the chain at an intermediate point above the counterweight 105 is a pivoted handle 107.

So long as the door 101 is closed, a cam 108 on the handle 107 depresses a switch 109. Then when the door 101 is raised by lowering the handle 107 the lowering of the handle 107 releases the switch 109. As shown in Figure IV, the switch 109 is connected in an electrical circuit with a solenoid valve 110 located in a gas line 111 that supplies gas to a burner that is in the form of a perforated pipe 112. Thus when the door 101 is opened, the releasing of the switch 109 causes gas to be supplied to the burner 112, and such gas is ignited by a conventional pilot light 113, so that a curtain of flame is directed in front of the opening in the hood 45.

The provision of a curtain of flame whenever the door 101 is opened is necessary if a combustible gas is being used as the protective atmosphere, in order to burn the gas that issues from the vestibule whenever the door 101 is opened and thus prevent the formation of an explosive air-gas mixture in the vestibule. When a carburizing operation is being carried out in the heating chamber, for example, the atmosphere supplied to the heating chamber and to the other portions of the apparatus may be an inflammable mixture of gases containing a large proportion of carbon monoxide as well as hydrocarbons.

Any of the various atmospheres used in heat treating operations may be employed in the present apparatus. If the protective atmosphere used is a non-inflammable atmosphere, such as an atmosphere consisting essentially of nitrogen containing only a small proportion of hydrogen or carbon monoxide, the burner 112 and the control apparatus shown in Figure IV may be omit-ted.

As the protective gas is supplied to the apparatus through the inlets 21, 27 and 60, the gas escapes past the door 101, and a vent may be provided in or adjacent the door if the normal leakage past the door is not sulficient.

The quenching liquid 35, which may consist of one of the known quenching oils or any other desired quenching liquid, is circulated in the quench tank by means of a propeller 114 that is driven through a shaft 115 by means of a motor 116 that is supported by a bracket 1 17. The bracket 117 is mounted on a plate 118 which forms a cover for an opening in the upper wall 119 of the quench tank. The quenching liquid is conducted to the propeller 114 through a passage formed in the bottom of the quench tank by a horizontal bafile 120 that partitions off the lower part of the quench tank. Depending from the plate 118 is a housing 121 containing curved baflles 122. The quenching liquid that is forced upward by the propeller 114 enters the housing 121 and thus is directed toward the left by the curved bafiles 122. A vertical baffle 123 that extends upward in the quench tank from the horizontal baffle 12%, and a registering vertical bafile 124 carried by the elevator 69 also restrict the flow of the quenching liquid so as to cause the liquid to flow downward through work contained in baskets supported on the lower platform 71 of the elevator.

In order to control the flow of the quenching liquid, a vertically slidable gate 125 is provided in the passage that conducts the quenching liquid to the propeller. The gate 125 can be moved vertically by a rod 126 that is adjustable by means of a hand wheel 127 threaded on the upper end of the rod, and is guided in its vertical movement by means of guides 128 extending along both of the lateral edges of the gate.

In order to maintain the quenching liquid at the desired temperature, cooling means or heating means, or both, may be provided in the quench tank. As an example of such means, Figure II illustrates an internally fired heating tube 129, similar to the internally fired heating tube 22 in the heating chamber 11.

In the operation of the apparatus illustrated in the drawings, the elevator 69 is initially in its upper position so that the rollers 100 on the lower platform 71 are aligned with the rollers 16 and 38. With the elevator in that position, baskets of work can be moved through the vestibule into the heating chamber. However, if the heating chamber is hot, the work should be permitted to remain in the vestibule, with the door 101 closed, for a period of time suflicient to permit substantially all traces of air to be purged from the vestibule by the protective gas that enters the vestibule continuously from the heating chamber and the cooling chamber.

If desired, a fan similar to the fan 56 may be provided in the heating chamber for circulating the atmosphere in the heating chamber during the heating operation.

After the heating of the baskets of work in the heating chamber has been completed, the work may be subjected either to rapid cooling by the quenching liquid or to slow cooling by the protective atmosphere circulating in the cooling chamber 51. Rapid cooling, for example, is use ful in quench-hardening operations, whereas slow cooling is useful after heating operations that are intended for relieving stresses or for age-hardening.

If the work is to be subjected to rapid cooling, the elevator 69 is brought to its upper position, and the baskets of work are moved from the heating chamber onto the lower platform 71 of the elevator.

The elevator then is lowered, under control of the air cylinder 74, to immerse the work in the quench liquid 35. While the work remains thus immersed, additional baskets of work may be charged through the vestibule into the heating chamber in the same manner as before.

Whenever it is desired to use slow cooling after a heating operation, the elevator is in its lowermost position when the baskets are transferred from the heating chamber to the vestibule, so that after it is transferred to the vestibule the work is supported on the carriage 79.

Then the carriage is moved into the cooling chamber 51 by means of the handle 88, and the door 61 is closed while the slow cooling operation takes place. During such a slow cooling operation, work may be transferred through the vestibule into the heating chamber after the elevator 69 is first raised slightly, using the positioning apparatus shown in Figure III to locate the elevator so that the rollers 90 on the upper platform 70 are in alignment with the rollers 38 and 16.

The baskets can be moved between the heating chamher and the vestibule in the known manner, without opening the door 101, by means of an operating rod inserted through a small opening that is provided in the door 101.

Having described the invention, I claim:

1. In a heat treating apparatus comprising a vestibule adapted to confine a protective atmosphere, a heating chamber extending from the rear of the vestibule, an auxiliary chamber extending from the side of the vestibule, and a tank of quenching fluid below the vestibule, in combination, an elevator openating between the vestibule and the tank, having a lower platform for receiving, from the heating chamber, work to be lowered into the tank, and an upper platform; tracks on the lower platform of the elevator and in the heating chamber that are in alignment when the elevator is in its upper position, to permit work to be moved along such tracks from the heating chamber onto the lower platform of the elevator; carriage tracks on the upper platform of the elevator and in the auxiliary chamber that are in alignment when the elevator is in its lower position, a work carriage movable along such tracks between a position on the upper platform of the elevator and a position that is in the auxiliary chamber and is entirely off the elevator; and additional tracks on the work carriage that are in alignment with the tracks in the heating chamber when the elevator is in its lower position and the work carriage is on the upper platform of the elevator, to permit work to be moved from the heating chamber onto the carriage.

2. In a heat treating apparatus as claimed in claim 1, a charging door in the front of the vestibule, and tracks on the upper platform of the elevator that are in alignment with the tracks in the heating chamber when the work carriage is off the elevator and the elevator is raised slightly from its lower position, to permit work to be moved through the charging door across the upper platform of the elevator along such tracks into the heating chamber.

3. In a heat treating apparatus as claimed in claim 2, a stop for arresting the elevator in its downward movement when the tracks in the auxiliary chamber are in alignment with tracks on the upper platform of the elevaltor, and a removable stop for arresting the elevator in its upward movement when the tracks in the heating chamber are in alignment with tracks on the upper platform of the elevator.

References Cited in the file of this patent UNITED STATES PATENTS 1,070,487 Knox Aug. 19, 1913 1,811,979 Smalley June 30, 1931 2,639,047 Ipsen May 19, 1953 2,639,138 Dow May 19, 1953 FOREIGN PATENTS 263,312 Great Britain Dec. 30, 1926

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