JPS6134065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum furnace, and is particularly used for vacuum heat treatment of processed parts, in which the processed parts are charged and then processed in an environment below atmospheric pressure, after which the furnace operation is interrupted. It is removed from the furnace without any damage.

Prior to this invention, vacuum furnaces for heat treating and processing metal articles were commonly used. However, until now, the method of operating a vacuum furnace was batch processing (batch processing).
processing) has been commonly used. As a result, the applications and uses of furnaces used for bulk processing have been limited to some extent. In this regard, bulk heat treatments result in the furnace being shut down after each heat treatment cycle to remove the treated workpiece from the furnace. And the results obtained from such heat treatments are not to mention the considerable time and effort expended in shutting down the furnace, removing the parts from it, reloading the furnace with material, and then heat treating a new batch. It is clearly inefficient. This is because the furnace operation is completely stopped between the removal of processed workpieces and the loading of new parts.

Some efforts have been made to operate continuous heat treatment furnaces using conveyor belts. However, such furnaces usually have an atmospheric pressure environment, that is, atmospheric pressure is introduced into the heating chamber of the furnace. US Pat. No. 3,782,705 discloses a continuous working vacuum furnace. And the furnace shown therein is capable of heat-treating parts without compromising the vacuum inside the furnace. However, this device is somewhat complex in its door arrangement and conveyor mechanism, and therefore the manufacture of such a furnace is relatively expensive. Other attempts have been made to heat treat under vacuum in continuous working furnaces;
It has been a problem to load and remove workpieces without compromising the airtightness of the heating chamber of the furnace.

The present invention continuously charges and processes workpieces through a heating chamber for heat treatment without breaking the vacuum in the heating chamber, and maintains the heating chamber at a predetermined atmospheric pressure when the workpieces are conveyed through the heating chamber. Concerning a vacuum furnace maintained at the following pressures and temperatures: To provide continuous operation of the vacuum furnace here embodied, the charging chamber is equipped with a unique vacuum-sealed door arrangement operable to move from a sealed vertical position to a substantially horizontal position, thereby The workpiece is then introduced into the charging chamber in preparation for loading into the heating chamber. An additional vacuum-sealed door device is provided to protect the heating chamber and to make it possible to remove the workpiece from the cooling station of the furnace without interrupting the heating chamber operations or breaking the vacuum therein. provided within the system.

Vacuum-sealed door systems are constructed and arranged to avoid high lifting equipment which typically increases the overall height of the furnace. Instead, each door is provided with an actuation mechanism that provides a combination of lifting and pivoting actions when the door is opened and closed.

The vacuum furnace embodied herein further includes a unique movement mechanism that provides linear movement of an operable drive coil spring to move the workpiece through various stations within the furnace. After the drive coil spring is moved linearly by the electric motor to move the workpiece, a reversing mechanism is provided to cause the drive spring to move backward in preparation for the next moving operation. . An unloading transfer mechanism located at the quenching station of the furnace is also configured to retrieve the workpiece from the heating chamber into the quenching station following the heat treatment operation, and to deliver the workpiece from the quenching station following the cooling operation. and a vertically movable drive spring operable to retrieve the workpiece.

Another feature of the invention is that the hydraulic fluid is circulated in a chamber adjacent to the furnace heating cooling jacket for cooling the hydraulic fluid used to operate the various motors for operating the door system, etc. The heating chamber cooling jacket constitutes a heat exchanger for the hydraulic fluid for effective cooling of the hydraulic fluid.

It is therefore an object of the present invention to provide a continuously working vacuum furnace for heat treating metal articles in an atmosphere below atmospheric pressure, in which the workpiece is heated for its heat treatment. It is advanced periodically through various furnace stations without breaking the vacuum of the heating chamber within the furnace. The next workpiece is periodically introduced into the furnace and moved through the furnace in an atmosphere below atmospheric pressure for its processing, after which the cooled workpiece does not interrupt the work of the heating chamber of the furnace. It is then removed from the furnace without breaking the vacuum there.

Other objects, features and advantages of the invention will become apparent from the following description of the embodiments, taken in conjunction with the accompanying drawings.

1 and 2, a continuously operating vacuum furnace, generally designated 10, which is an embodiment of the present invention will now be described. As described below, this vacuum furnace 10 is used to heat treat metal parts under conditions below atmospheric pressure, and is capable of continuously receiving workpieces and without interrupting the operation of the furnace heating chamber.
And the workpiece can be processed without damaging the vacuum therein. This vacuum furnace 10 is used for various heat treatment operations such as sintering and brazing, and is particularly used for continuous decarburization of metal parts under vacuum.

Referring to FIGS. 3, 4, and 5, the illustrated vacuum furnace 10 includes a charging station 12 (FIG. 3), a heating chamber 14 (FIG. 4), a quenching station 16 (FIG. 5), and a discharge station. Station 18 (Figure 5)
It is equipped with As will be described later, the charging station 12, the heating chamber 14, the quenching station 16, and the delivery station 18 are adjacent and interconnected to form the vacuum furnace 10 described above. The units of these stations are easily assembled, and some of them are constructed into integral units or modules in order to change the position of the units according to requirements, as will be explained later.

Referring to FIG. 3, the charging station 12 is mounted on a foundation 20 that includes spaced beams 22 having casters 24 at the lower end to facilitate assembly of the charging station 12 with other furnace units. It is being Further, as shown in FIG. 6, a body 28 forming the charging chamber of the charging station 12
Mounted on the spaced apart beams 22 are supports 26 for supporting the beams. The body 28 includes a generally convex front wall 30 having a central opening for mounting a tubular door frame 32 thereon. Also,
A flange 34 is attached to the rear end of the body 28. In addition, a separable intermediate connection portion 38
is attached to a flange 34 of the fuselage 28 via a rear flange 36. Intermediate connecting portion 38 includes a forward flange 40 sealed to the flange of heating chamber 14 (FIG. 4), as will be explained further below. Also, a convex wall 41 is formed integrally with the connecting part 38, which together with the front wall 30 constitutes a fuselage structure. Further, a wall 43 is formed integrally with the connecting portion 38 and forms a front wall of the heating chamber 14 . Then, the inner door frame 44 is connected to the convex walls 41 and 43.
The charging chamber and the heating chamber 14 are connected to each other by this. Flanges 34 and 36 are secured together by suitable bolts;
The body 28 and the connecting portion 38 are modular so that they can be exchanged at various positions depending on the application.

A charging platform 42 formed as part of the charging station 12 externally to the charging chamber formed by the body 28 has spaced inclined supports 45 connected to the base 20 and at its top end. A horizontal support 46 is fixed. The inner end of this horizontal support 46 is locked into a sleeve 47 fixed to the underside of the door frame 32. Vertical support 4
8 are attached to horizontal supports 46 to support spaced loading tracks 50. This charging track 50
are formed in spaced apart members between which a plurality of rollers 52 are mounted for receiving a workpiece carrier 53 on which a workpiece 54, shown schematically in FIG. 3, is placed.

One of the unique features of this invention is the operable door system that seals and provides communication between each station. As will be explained later, each door system not only provides complete communication to the station with which it communicates, but also because these door systems do not protrude above the vacuum furnace, the entire vacuum furnace system It is configured to reduce the height of the

9 and 10, one of these door structures is illustrated and designated generally at 56. The illustrated door arrangement 56 is provided on the charging station 12 to interrupt communication between the charging platform 42 and the interior of the charging chamber within the fuselage 28. Note that the structural arrangement and function of the other vacuum-sealed door devices are the same as those shown in FIGS. 9 and 10. This door device 56 is a door member 58
, which is generally rectangular in general shape and designed to seal an opening formed in a door frame 32 attached to an opening in the front wall 30 of the fuselage 28 . To this end, a lip groove is formed in the inner surface of door member 58 to receive an O-ring seal 60, as shown in FIG. O-ring seal 60 typically engages the adjacent edge of door frame 32 in a sealing engagement when door assembly 56 is positioned in its closed position. An opening is formed in the door member 58 for receiving the frame to which the viewing port 62 is attached;
The viewing port allows observation of the interior of the fuselage 28, ie, the waiting room, after the door member 58 is moved to its closed position. A spaced trunnion 64 is secured to the exterior surface of door member 58, and the trunnion is connected to rod 66.
It is rotatably supported. A bearing block 68 is also secured to the outer surface of the door member 58 to support the sprocket gear as described below.

Fixed to the sides of the door frame 32 are spaced brackets 69 and 70 to which bearings 72 and 74 are mounted. These bearings 72
A drive shaft 76 is rotatably supported by and 74, and the end thereof is engageable with a hydraulic motor 78. A link 80 is fixed to the drive shaft 76 at a position remote from the side surface of the door member 58, and the other end of the link 80 is fixed to the outer end of the rod 66. Therefore, when the drive shaft 76 rotates, the link 80 rotates together with the shaft, causing the door member 58 to rotate.

A feature of the operation of the door device 56 is that when the door member 58 is rotated between the closed position and the open position, the door member 58 is rotated in the opposite direction around the axis of the rod 66. Due to the operation of the door member 58 in this manner, less space is required for its movement, thereby allowing the charging platform 42 to be located closer to the charging cylinder 28. Referring again to FIGS. 9 and 10, a sprocket gear 82 is shown secured to a hub mounted to the front wall of the fuselage 28. In addition, the sprocket gear 8 with a smaller diameter than the above-mentioned
4 is attached to a hub fixed to block 68, and block 68 is fixed to door member 58 as described above. A chain 86 interconnects sprocket gears 82 and 84.
This chain 86 is provided to perform rotational movement relative to the shaft 76 between the rod 66 and the door member 58 fixed thereto, as will be described later.
As shown in the figure, the diameter ratio of the sprocket gear 82 to the sprocket gear 84 is 2:1, so the amount of rotation of the door member 58 connected to the chain via the block 68 and the sprocket gear 84 is determined by the rotation of the drive shaft 76. This is twice the amount of movement. Therefore, the drive shaft 76 is connected to the link 80 and the door member 58 coupled thereto.
The interconnection of sprocket gears 82 and 84 by chain 86 produces a 2:1 counter-rotational movement of door member 58. As clearly shown in FIG. 10, when the link 80 fixed to the drive shaft 76 is moved upwards to a horizontal position, the door member 58 is moved simultaneously and vice versa, i.e., the shaft 76 and the link 8
It is rotated counter-rotated towards an upward position approximately horizontal to zero. that the counter-rotational movement of the door member 58 is achieved within a relatively small space;
It is shown in phantom in FIG. 10 that the reverse rotation of the door member not only effectively positions the door member in the open position as shown, but also places the O-ring seal 60 in an upper, protected position. This can be seen from the movement of the door members. As will be explained later, a door device located inside the furnace and adjacent to the heating chamber is operated in the same manner as described above and is protected behind the door member when the door member is opened. By positioning the O-ring seal 60 in a similar relationship, the seal within the internal door system is protected from heat radiated from the heating chamber.

Longitudinal spaced track portions 88 and 90 are mounted within the fuselage 28 in alignment with the track portions of the charging platform 42, comprising a pair of spaced track members 88 and 90, which A roller similar to the roller 52 is rotatably mounted between them. A workpiece carrier 53 carrying a workpiece 54 is supported by rollers in track sections 88 and 90 for movement through the body 28 and into the heating chamber 14 as will be explained below.

Another unique feature of this embodiment of the invention is the loading and unloading transport for moving the workpiece carrier 53 through the body 28 into the heating chamber and thereafter to the quench station and the unload station. It is a mechanism. 3rd, 11th and 1st
In FIG. 2, the entire loading and transferring mechanism is indicated at 92. As discussed below, the output transfer mechanism is generally similar in structure and operation to the charge transfer mechanism. The charge transfer mechanism 92 is provided with an elongated flexure drive spring 94, which is a conventional coil spring, and extends from the interior of the body 28 out of the body 28 and then within the tubular housing below the body 28, as shown in FIG. It has been extended to In order to send out the deflection drive spring 94 linearly in the vertical direction, this drive mechanism 92
is provided with a drive shaft 96, which is connected to a motor 98 mounted on a bracket support 100 by bolts 101, as shown in FIG. Bracket support 100 is mounted on a base 102 that is secured to a plate 104 that is internally secured to fuselage 28. Also supported by the base 102 are spaced apart brackets 106 with suitable bushings 107 mounted therein for supporting the shaft 96. Spaced pillow blocks 108 are also attached to a bracket 106 which supports a bearing 110 which rotatably supports shaft 96. The drive pulley 114 is attached to this bracket 10.
6, the drive pulley is formed with a recess 116 in which spaced teeth 117 are formed. As shown in FIG. 13a, these teeth 117 are formed only in the bottom portion of groove 116 and are pitched to accommodate the helical coil of flexure drive spring 94. By positioning the teeth 117 in this manner, the coil of the flexure drive spring 94 is engaged with the teeth 117 and is prevented from dislodging from the groove 116 as the spring is moved longitudinally during loading or retracting operations.

To produce this linear movement of the flexure drive spring, the teeth 117 of the drive pulley 114 are flexed to cause the drive spring 94 to flex.
A retaining roller 118 is provided to effectively hold the coil in engagement with the coil. As shown in FIGS. 11 and 13, the holding roller 118 also has groove 1.
20 whose groove matches the shape of the coil of spring 94 and fits into the coil to urge the spring into groove 116 of drive pulley 114. The needle bearing fixed to the roller 118 is the shaft 12
6 and thereby rotatably mount the roller 118 on the shaft 126. As will be explained later, this roller 118 is flexibly driven into a position such that the forwardmost end of the flexure drive spring 94 causes the workpiece carrier 53 to be transferred so that the workpiece carrier 53 is transferred into the heating chamber 14. It is provided to hold the spring. For this purpose, the roller 118 is mounted in position on a deflection drive spring 94 and a pivot bracket 128 on the shaft 126, and is held in position relative to the drive shaft 96 on which the drive pulley 114 is mounted.
As shown in FIG.
includes a spaced apart plate 130 having an upper opening 132 for receiving the reduced diameter shaft 124 and shaft 126;
It is equipped with Also, inside this plate 130, a shaft 9 is provided.
A larger lower aperture 134 is also formed to receive a suitable bushing 136 for bearing 6. A guide tube 138 (FIG. 11) having a slot 139 formed therein is secured between the plates 130 and extends forward thereof to receive the flexure drive spring 94. A lever 140 is provided and secured to one end of the shaft 126 for pivoting the pivot bracket 128 supporting the retaining roller 118 (FIG. 13). Lever 140 is fixed to a motor shaft 142, which shaft is connected to a hydraulically operated motor that is sequentially actuated to pivot lever 140, thereby pivoting bracket 128 and the support thereon. This causes a pivoting movement of the holding roller 118. Further, as shown in FIG. 12, a push rod 144 is fixed to the distal end of the flexure drive spring 94, and the push rod 144 extends beyond the guide tube 138 into the slot 1.
It has been extended to 46 (Fig. 11). Groove 1
Pusher element 1 is inserted into 46 by pin 148.
50 is fixed and the pusher element cooperates with the pusher rod 144 to drive the workpiece carrier, with the workpiece carrier and the pusher element being engaged during the transfer operation. The key stock 151 is the guide tube 1
38 through slot 139 and engages pusher rod 144 whose keystock prevents rotation of the pusher rod, thus allowing pusher element 150 to be inserted into the guide tube within body 28. I will guide you as follows. The deflection drive spring 94 is driven longitudinally by the rotation of the drive pulley 114 and is connected to the pusher rod 144 and pusher element 1 fixed thereto.
50 moves linearly with spring 94. 1st
As further shown in FIGS. 1 and 12, an elongate tubular guide member 152 is mounted within the fuselage between the track sections 90 and includes a slot 154 for receiving the pusher element 150. There is. The flexure drive spring 94 guides the pusher rod 144 within the body 28, the pusher element 150 is received within the slot 154, and the pusher rod 144 and flexure drive spring 94 are inserted into the tubular guide member 152. This pusher element 150 is engageable with the rear crossbar of the workpiece carrier 53. When drive spring 94 is then moved longitudinally within body 28 , the workpiece carrier is moved through body 28 and door frame 44 into heating chamber 16 .

As shown in FIG. 3, the rear portion of the flexure drive spring 94 projects outwardly from the body 28 and extends into and parallel to a sealed tube 156 which projects curvilinearly below the body. The flexural drive spring 94 therefore moves forward within the sealed tube 156 during the feed movement and when retracted the sealed tube 15
Move backward within 6. In order to effect a reverse movement of the flexure drive spring 94 to retract the pusher rod 144, it is necessary to reverse the operation of the motor 98 mentioned above, and a spring reversing device is provided for this purpose. A spring reversing device is illustrated in FIGS. 16 and 17 and includes a bustle 158 attached to the base 20 and receiving a sealed tube 156 therein.
The second bustle 1 is spaced apart from the bustle 158.
60, which is also attached to the base 20, with a cylinder 162 connecting the two husks in a sealing relationship. A sealed tube 156 projects in sealing relation through the bustle 158 and cylinder 162 into the bustle 160 through which the spring 94 extends.

As shown in FIG. 17, the flexure drive spring 94 housed within the sealed tube 156 has a tab 166 coupled to its end, which tab 166 is located within the portion of the sealed tube 156 located within the cylinder 162. and extends upwardly through a slot 168 formed in the. This tab 166 is connected to battles 158 and 160, respectively.
arm 170 mounted for pivoting within the
and 172, and tab 166 is located between motor 98 and 172.
is moved by the flexure drive spring 94 between arms 170 and 172 when the flexure drive spring 94 is moved during the feed operation. As shown in FIG.
Vacuum seals 173 and 174 to the outside of 60, respectively.
and are interconnected by a linkage to an elongated continuous rod. Elongated connecting rod 175 has limit stops 176 and 178 mounted intermediate its ends, and extending between limit stops 176 and 178 is a roller 180 secured to switch arm 182 of limit switch 184. Limit switch 184 is electrically interconnected to motor 98 and is configured to control the direction of rotation of motor 98 to send flexure drive spring 94 in either a forward or reverse direction. During the transfer stroke or charging stroke, the deflection drive spring 94
is moved to its extreme position, the tab 166 abuts the arm 170 and causes a corresponding longitudinal movement of the connecting rod 175, thereby reversing the action of the limit switch 184. Operation of limit switch 184 then reverses operation of motor 98, immediately retracting the drive spring to its initial position and positioning pusher rod 144 for the next transfer operation. When tab 166 is returned to its initial position, it engages arm 172, thereby moving connecting rod 175 to again reverse the operation of motor 98. A time delay relay can be utilized to delay activation of the motor for the next drive spring feed movement.

As previously mentioned, a retaining roller 118 is provided to positively urge the flexure drive spring 94 into engagement with the drive pulley 114. Once the workpiece carrier 53 is introduced into the fuselage 28, the rollers 118 will normally limit inward movement of the workpiece carrier. To allow free movement into the body 28 of the workpiece carrier, the pressure roller is pivoted forward of its normal position by the pivot bracket 128 from the position shown in solid lines to the position shown in dotted lines in FIG. is pressed down, thereby pushing down roller 118, guide tube 138, pusher rod 144 and pusher element 150. The processed parts carrier 53 is mounted on the body 28 in front of the pusher element 150.
After entering, the pivoting bracket 128 is then returned to its normal position by a pivoting movement of the lever 140, so that the pusher element 150 is moved into engagement with the rear crossbar of the workpiece carrier 53; Then, the holding roller 118 is bent again and the drive spring 94
and urges it into driving relationship with drive pulley 114.

When the workpiece carrier 53 is guided into the body 28 , an inner door 186 placed in a vacuum-sealed position relative to the door frame 44 connects the body 28 and the heating chamber 16 .
Seal the space between. Door device 18 including door member 188
6 is moved into and out of the vacuum sealed position in the manner described above with respect to the door member 58 of the door arrangement 56. In this regard, door member 188 is normally in a sealed position when door member 58 is opened to receive workpiece carrier 53 for introducing workpieces into body 28. As will be explained, since the heating chamber 14 is always maintained under a predetermined vacuum and temperature, the operation of the furnace is such that a vacuum and a predetermined temperature are maintained within the heating chamber 14 during all stages of furnace operation. is continuous.

Before introducing the workpiece into the body 28, the door device 1
86 is moved to a sealed position, after which atmospheric air is introduced into the fuselage until atmospheric pressure is achieved. According to the cycle of work, the door device 56 is operated to move the door member 58 to its open position. After the workpiece has been moved into the fuselage 28 and the door member 18
8 is still in the closed position, the door member 58 is sealed and the body 28 is closed so that the vacuum therein is removed from the heating chamber 14.
It is evacuated until the vacuum is approximately the same as that of . The door member is then moved to the open position and the workpiece 54
is transported through the door frame 44 into the heating chamber by the longitudinal feed movement of the flexure drive spring 94.

4 and 7, the heating chamber 14 has an inner shell 1 having a roughly circular cross-sectional shape as shown.
90 and is mounted within an outer shell 192, which outer shell has a generally rectangular cross-sectional shape as shown in FIG. Outer trunk 192
Suitable supports are provided for positioning the inner shell 190 therein, and the outer shell is supported by spaced beams 22 extending longitudinally of the furnace. The inner shell 190 is water cooled, and the space formed between the inner shell and the outer shell forms a water jacket;
Water is circulated therethrough to effectively cool the inner shell 190 during operation of the furnace. Inward slope wall 1
94 (FIG. 7) is an inner chamber 1 extending the full length of the outer shell 192 and in which hydraulic fluid is circulated.
96, this inner chamber 196 serves as a cooling chamber for the hydraulic fluid used in the various motors throughout the system.

The front end of the inner barrel 190 has an annular flange 197 fixed thereto, which flange connects the connecting portion 38.
and is secured to a flange 40 for interconnecting in sealing relation with the heating chamber. The other end of the inner barrel 190 also has an annular flange 198 fixed thereto, which is connected to the flange 199 of the intermediate connecting portion 200.
The connecting portion is fixed to the dome wall 2 with an opening formed therein to receive the door frame 202.
01 is formed. A vacuum-sealed door system 203 is attached to the door frame 202 and includes a door member 204 that is constructed and operated similarly to the door system 56 and that is connected to a quench station from the heating chamber 14. 16.

A heating area defined by a cage, indicated at 205, is provided inside the inner shell 190 of the heating chamber 14. A support 206 for the cage 205 mounted inside the inner barrel 190 is provided on the outside of the cage 205 . Cage 20 is a mesh of mild steel wire.
5, comprising outer layers 208, 210, 214 of alumina silica fibers and inner layers 209, 211, 212 of graphite fibers therebetween.
are fixed, and these inner and outer layers form a heating area. There are terminal portions of a plurality of heating elements 216 protruding through the outer layers 212 and 214 and the wire mesh 207 of the cage 205, which are of tubular construction and which are also woven of the type described in U.S. Pat. No. 3,525,795. Made of graphite material. A rod 217 electrically connected to a terminal 218 is coupled to the terminal portion of the heating element 216, and the terminal 218 is coupled to a suitable electrical connection extending outside the heating chamber 14 and interconnected to a power source external to the furnace. connected to the device. Thermal doors 220 and 222 are mounted adjacent the outer edge of gauge 205, as shown more clearly in FIG. thermal door 22
0 controls entry and exit through the front opening 223 of the cage 205, while the thermal door 222 controls entry and exit through the rear opening 224. Both thermal doors 220 and 2
22 is connected to an adjacent vacuum-sealed door system, and activation of door system 186 causes corresponding activation of thermal door 220. Similarly, the heating door 222 is moved to the open and closed positions in accordance with the operation of the vacuum sealing door device 203 that controls access between the heating chamber 14 and the quenching station 16. Furthermore, as shown in FIGS. 3 and 4, the track portion 228 is connected to the door frame 44.
It extends from the thermal door 220 to the thermal door 220 . The pusher rod 1 is aligned with the guide member 152 during the workpiece transfer operation.
44 and a flexure drive spring 94 received therein is a tubular guide member 229 located intermediate the track elements of track section 228. A separately mounted track section 230 is located within the heating area inside the cage 205, while a track section 232 is located downstream of the cage 2.
05 and extends into a tubular door frame 202 located on the discharge side of the heating chamber 14. A tubular guide member 233 is located intermediate the track elements of track section 232 to receive a pull bar and a retraction spring therein as described below. cage 2
The longitudinal dimensions of 05 are such that three workpiece carriers 53 arranged vertically next to each other are accommodated therein. Therefore, as each carrier 53 is introduced into the charging barrel and subsequently moved into the heating chamber 14, the last loaded carrier engages the preceding one and the subsequent actuation of the transfer mechanism. The deflection causes the drive spring 94 to advance the vehicle and the load therein forward to the next position. A retraction or unloading mechanism is utilized to remove the front load from the heating chamber to position it at the quench station 16, and a loading and unloading mechanism cooperates to sequentially move the workpiece through the various stations. to move forward. The workpiece is positioned in the heating chamber during at least three feeding operations, so that the heat treatment operation of the workpiece contained on the carrier within the heating chamber is suitably controlled. If desired, a fan 238 communicates with the duct for circulating the decarburizing gas within the heating chamber during the decarburizing operation.
may be installed within the heating chamber 14.

Following the heat treatment operation, the workpiece is transferred from the heating chamber 14 to the quenching station 16 into which it is controlled by a vacuum-sealed door arrangement 203. This vacuum sealed door device 203
The operation is similar to that of the door device 56 described above, and the movement of the door member 204 of this vacuum-sealed door device 203 is the same as that of the door member 58 described above. A door frame 202 extending into the quench station 16 provides communication between the heating chamber 14 and the quench station 16.
And, as shown in FIG. 5, the door device 203 is operable to seal the communication between the heating chamber 14 and the quenching station 16 as required.

As shown in FIG. 5, the quench station 16 is comprised of a quench tank and includes an inner shell 240, the axis of which is perpendicular to the shell 28 and the heating chamber 14. The inner shell of quench station 16 is mounted in spaced relation to outer shell 242, which matches the surface of the furnace. Inner and outer shells 260 and 242 define a cooling space 244 therebetween, through which a cooling fluid is circulated to effectively cool the quench station, as is well known in the art. A dome 246 is attached to the inner shell 240 and the outer shell 242;
Additionally, a cooling space is provided to effectively cool the dome 246. Connected to the outer shell 242 is a connecting portion 200 which together with the outer shell forms part of a cooling jacket through which coolant is circulated. An opening is also formed in the wall of the inner shell 240 through which the door frame 202 extends into sealing engagement therein. A hydraulic ram 250 is attached to a support 248 located at the bottom of the outer shell 242. A piston 252 is mounted to reciprocate within a hydraulic ram 250, and a pulley 25 is attached to the upper end of the piston 252.
4 is fixed. A cross beam 256 is located at the top of the quench station 16 with idler wheels 258 and 260 rotatably mounted therebetween. There are spaced track members 262 fixed to suitable supports and extending approximately the height of the quench station 16, with an elevator 264 mounted therebetween for raising and lowering movement. elevator 2
64 includes a frame 266 with spaced apart track elements 26 on the lowest end of the frame.
A portion of the track constituted by 8 is attached. Rollers 269 are mounted on this section 268 of the track and support the workpiece carrier 53.
The elevator 264, together with the workpiece carrier 53 placed on the track section, moves vertically toward and away from the bottom of the quenching tank in order to rapidly cool the workpiece load 54 located on the carrier vehicle 53. It is configured. A cable or chain 270 is provided for this purpose and is connected to a pulley 25 to be fixed at one end to a fixed point on the quench tank and at the other end to the top of the elevator 264.
It extends around 4. In this manner, when hydraulic ram 250 vertically moves pulley 254 to the position shown in phantom in FIG.
, along with the workpiece carrier and workpieces thereon, descend to the bottom of the quench station to submerge the workpiece carrier and workpieces thereon into the quench liquid 272 . A motor 273 is attached to the bottom end of the quenching station,
During the quenching operation, a circulation fan 271 is operated to effectively circulate the quenching liquid 272 as indicated by the arrow in FIG. As shown in FIGS. 5 and 8, a spring-actuated clamping element 275 is mounted at the end adjacent the portion of the elevator track, and the clamping element 275 is moved upwardly as the elevator descends; An end barrier is formed to hold the vehicle above the elevator.

Also, the portion of the track 274 located between the door assembly 203 and the elevator 264 is mounted on a suitable support within the quenching station to transport the workpiece carrier 53 from the door frame 202 to the portion of the track of the elevator 264. I will guide you to the top. A section 276 of the track is also located downstream of the elevator 264 and receives the workpiece carrier 53 thereon after the quenching operation. A guide tube 277 for guiding the drive spring is mounted in the middle of the track elements on track section 274 and is aligned with another guide tube 232 . Moreover, as shown in FIG. 8, the track element 268 is further
64, which guide tube 278 is supported by guide tube 23 when the elevator is in the raised position.
2 and 277. Guide member 290
is attached between the track elements of track section 276;
All of these aligned guide tubes accommodate the unloading rod and retraction drive spring of the unloading mechanism 281. The unloading mechanism 281 operates in a manner generally similar to that described above for the loading mechanism and is received on a drive pulley 283 similar to drive pulley 114. Drive pulley 283 is mounted on a drive shaft for rotation and is rotatably driven by the same drive motor as drive motor 98 . The holding roller 284 engages with the drive pulley 283, and the thirteenth
It can be tilted inwardly toward the quenching station by a loading tilting device similar to the loading tilting device 128 shown. A second retaining roller 286 is located downstream and adjacent to the drive pulley 283 and includes a drive spring 282 similar to the flexure drive spring 94 described above, which is attached to a sealed tube 288 disposed in a generally vertical position below the drive spring 282 . Push it inside. Unloading rod 29 with a pivot retraction element 292 attached to its end
0 is fixed to the innermost end of the drive spring 282.
The holding roller 284 is attached to the elevator 2 following the quenching operation.
During the unloading operation of the transport vehicle 53 from 64, the unloading tilting device can move the unloading rod 290 and the retraction element 292 in a downward direction. The vehicle is retracted from the elevator track section onto the track section 276. It is clear that since the normal working tension on both springs 94 and 282 is less than their breaking tension, the springs will not stretch sufficiently to operate the loading and unloading mechanism.

Further, as shown in FIG. 5, a door frame 294 is mounted within the inner and outer shells 240 and 242 of the quenching station, and the unloading mechanism 281 is mounted therein. A door arrangement 296 is attached to the outermost end of the door frame 294 and includes a door member 298 that controls access through an aperture 300 formed in the door frame. Door device 296 has a similar structure to door device 56 described above and operates in the same manner. Door member 298 is movable toward and from a closed position for vacuum sealing an opening 300 in door frame 294 and for receiving transport vehicle 53 as it is removed from the furnace following a quench operation. discharge station
The portion 302 of the track forming the door device 296
It is located outside of.

As previously mentioned, the carriage 53 with the workpiece 54 placed thereon is moved through the body 28 into the heating chamber by means of a drive spring and a pusher rod 144 to which a pusher element is fixed. The vehicle loaded into the body 28 is moved forward by the drive spring 94 until it engages the previous vehicle in the heating chamber. In this way, the forward transport vehicle is pushed and moved one after another by the following transport vehicle. The last carriage is then conveyed into the heating chamber by the drive spring 94 and pusher rod 144, which extend through guide tubes 152 and 229 during its transport movement. The processed parts transport vehicle 53 then extends the unloading rod 290 and the unloading drive spring 282 into the heating chamber 14 through the guide pipes 276, 278, 277, 233. It is discharged from. The retraction element 292 is pivotable and movable behind the crossbar of the workpiece carrier upon engagement with the transverse bar of the workpiece carrier;
There it is locked behind the transport bar. The retracting movement of the drive spring then positions the forwardmost vehicle in the heating chamber on the track section of the elevator 264 with the heated door opened through the door frame 202 by means of 222 and by means of the opened door device 203.
Pull. At this point spring 282 and unloading rod 290
The tilting device is actuated to push down the unloading bar and disengage the retraction element 292 from the vehicle crossbar. Continued rearward movement of drive spring 282 by its drive motor causes the unloading bar to retreat from the elevator, now freely descending into the quench liquid.
Following the quenching operation and the raising of the workpiece to the upper position, the unloading mechanism again moves the unloading rod 2 until the retraction element once again engages the crossbar of the workpiece carrier.
90 and retraction element 292 are actuated to advance toward the carrier. The reverse movement of the drive spring 282 causes the portion 3 of the track at the delivery station 18 to
Pull the cart from the elevator onto the track section in the door frame 294 for unloading to 02.

As stated above, the sections of each track located in the furnace station are all of generally identical construction; and to illustrate the construction of the sections of track and the rollers mounted thereon, 14th
Please refer to the figure and FIG. In this connection, reference is made to the track section 230 and the rollers mounted thereon. This is because the part of this orbit is the heating chamber 14.
This is because they are located inside and are made of special materials to withstand the high temperatures experienced during heat treatment operations. Track section 230 includes pairs of spaced members 304 supported by a series of notched bridge supports 306 . Track member 30
4 and the bridge support 306 are preferably made of molybdenum. This is because this material is capable of withstanding the relatively high temperatures experienced during furnace heat treatment operations. a plurality of spacer elements are spaced apart from the track member 304;
A bolt 310 extends through them, with the end of the bolt 310 projecting through a suitable opening formed in member 304 and having a receiving nut thereon. Spacer 308, bolt 310 and nut 312 are also formed of molybdenum material. Roller 3 installed between members 304
13 is formed of graphite material and is therefore heat resistant and is rotatably mounted on tungsten pin 314. To secure pin 314 within member 304, a recess is formed in the member, as shown at 316, in which pin 314 is received. As previously mentioned, the side frames of the carrier 53 are received on rollers 313 and
3 is free to rotate about pin 314 thereby imparting movement to carriage 53 on portion 230 of the track through heating chamber 14 . The portion of the track 232 located within the heating chamber 14 is also constructed similarly to the portion of the track 230, and the portions of the track that are not exposed to excessively high temperatures are similarly constructed, except that the components of these track portions are The material used is mild steel. Furthermore, the rollers of these latter track sections are provided with internal bearings to facilitate their rotation.

A chamber 196 is formed within the outer shell 192 of the heating chamber 14 by positioning a plate 194 within the outer shell 192 and at an angle thereto. Further illustrated in FIG. 18 is a chamber 196 provided for the circulation of hydraulic fluid used to operate the various hydraulic motors of the system. An inlet 318 in communication with the hydraulic system extends into chamber 196 and directs hydraulic fluid therein. A filter 320 is also located within chamber 196 and communicates with suction pump 322 .
22 directs hydraulic fluid to the hydraulic system. It will be appreciated that the cooling chamber defined between the inner shell 190 and the outer shell 192 of the heating chamber 14 is effective in extracting heat from the hydraulic fluid circulating through the chamber 196. Cooling room 19
6 thus avoids the use of external heat exchanger units for the hydraulic system. and it would normally be used in furnaces of the type implementing the present invention.

During operation of the device, the charging cylinder 28 in the charging station 12, the heating chamber 14 and the quenching station 1
6 are all operated under vacuum conditions during the various stages of furnace operation and for this purpose the first
It is understood that it is in communication with the vacuum pump 324 shown. Vacuum line 326 is interconnected with vacuum lines 328, 333 and 332 to evacuate the various stations of the furnace at the required time intervals. Although not shown, conventional valves are utilized to control the vacuum at each site, and conventional discharge lines are also provided at the charging station and quench station to introduce atmospheric air into the station. There is.

Operation To explain the operation of this vacuum furnace 10, it is assumed that the heating chamber 14 and the quenching station 16 are in normal operation and evacuated to a predetermined vacuum pressure. At this point, the heating chamber is evacuated to less than 500 microns and the quench station is backfilled with nitrogen and operating at a vacuum of 250 mm of mercury.
All doors are closed and sealed, and the pressure inside the fuselage is atmospheric. Assume further that there is a workpiece on elevator 264, placed in a quench liquid, and undergoing a quench cycle. The workpieces are located in a charging chamber within the fuselage 28, and three workpieces are placed vertically end-to-end within the heating chamber 14. A workpiece is positioned on the charging platform 42 in preparation for entering the charging chamber. While maintaining the conditions as described above, the elevator 264 ascends to the unloading station with the workpiece thereon. The quench station 16 is then purged with nitrogen to atmospheric pressure, after which the door device 296
is operated to open the door member 300. The now fully heat treated quench load is manually collected onto the track section 302 at the discharge station for removal. Door assembly 296 then closes door member 298 and the quench tank is evacuated to approximately 500 microns to remove contaminants created when the last load was quenched and then removed from the quench station. After that, the quench tank was filled with nitrogen to 254 mm.
Refill the Hg vacuum and then maintain it for the predetermined immersion period. Heating chamber 14 was then heated to 254 mm with nitrogen.
Refilled with Hg vacuum. After both the heating chamber and the quench station are at a 254 mmHg vacuum, door device 203 is actuated to open door member 204, which simultaneously opens thermal door 222. The unloading mechanism is actuated to transfer the next load to elevator 264, which immediately descends into the quench liquid to begin the quench cycle. The door device 203 is the door member 204
and the thermal door 222 is also closed. The heating chamber is then evacuated again to approximately 500 microns.

In preparation for moving the workpieces in the charging chamber into the heating chamber, the body 28 is evacuated to 500 microns and the door device 186 is operated to open the door member 188, which simultaneously opens the thermal door 220. The loading mechanism is operated to transfer the workpiece from the charging chamber into the heating chamber, and the transfer operation advances the two remaining workpieces within the heating chamber. Door device 186 then seals door member 188, which door member is connected to thermal door 220.
is closed and the fuselage 28 is refilled with nitrogen to a vacuum of 127 mm Hg. Thereafter, the shell is brought to atmospheric pressure and the charging door 56 opens the door member 5 for charging workpieces on the platform into the shell 28.
8 is operated to open. Door member 58 is then closed and the cycle repeats.

It should be understood that the vacuum pressures cited in the work cycle description above are only representative of one work cycle and that the work conditions used will be predetermined by the heat treatment requirements of the workpiece. . The temperature within the heating chamber will also be varied according to the workpiece to be heat treated and the time intervals for the cycles will again be predetermined according to the heat treatment requirements.

Because of the modular construction of the fuselage 28 and connecting sections 38 and 200, it was also contemplated to include an atmospheric cooling chamber in place of or in conjunction with a liquid quench station. Various heat treatment operations can be performed by the furnace, and include carburizing, sintering,
Brazing and other conventional processing could be accomplished with the furnace without any changes to the furnace construction.

The loading mechanism, the unloading mechanism, the evacuation and scavenging of the fuselage 28 and the quench station 16, the operation of the various motors controlling the movement of the quench elevator are all automatic and the operation of the various motors controlling the movement of the metal parts to be heat treated are all automatic. It goes without saying that the timing is adjusted according to the characteristics. With a suitable console located near the vacuum furnace 10 and electrically connected to the various operating mechanisms, the system is preconfigured and upon actuation of the starter motor, a cycle is initiated and executed automatically. . Of course, the loading of the carrier into the charging shell 28 and its withdrawal at the discharge station can of course be carried out manually, but it can also be accomplished automatically if required. It is possible.

While the specific construction of embodiments of the invention is illustrated and described herein, those skilled in the art will appreciate that various modifications and rearrangements of parts may be made within the spirit and scope of the underlying inventive concept. It will be obvious that what may be done without departing from this and that the invention is not limited to the particular forms shown and described herein except as indicated by the appended claims.

[Brief explanation of the drawing]

FIG. 1 is a side view of a continuous heat treatment vacuum furnace according to an embodiment of the present invention, FIG. 2 is a plan view thereof, and FIG.
A cross-sectional view taken along line 3--3 of the figure shows the charging chamber including the loading vestibule and the workpiece vehicle transfer mechanism. FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 2, showing the heating chamber. FIG. 5 is a cross-sectional view taken along line 5--5 of FIG. 2, showing the quenching station, the heating chamber, and the delivery station including the unloading mechanism for retracting the workpiece carrier from the quenching station. FIG. 6 is a front view of the vacuum furnace embodiment taken along line 6--6 of FIG. FIG. 7 is a cross-sectional view of the furnace heating chamber along line 7--7 of FIG. Figure 8 is line 8 in Figure 1.
FIG. 8 is a cross-sectional view of the quenching station along line -8. FIG. 9 is a perspective view of the door device and its operating mechanism located on the charging station. FIG. 10 is a partial vertical cross-sectional view of the charging station door assembly showing the successive movement of the door member from the closed position to the open position. FIG. 11 is a plan view of the workpiece carrier transport mechanism, the pressure roller device for the drive spring, and the tilting mechanism therefor. 12 is a cross-sectional view taken along line 12-12 in FIG. 11; FIG. 13 is a cross-sectional view taken along line 13-13 in FIG. 11; and FIG. 13a is an end view of the drive pulley used in the transfer mechanism. It is. 14 is a side view of the portion of the track within the heating chamber over which the workpiece carrier is transported, and FIG. 15 is a cross-sectional view taken along line 15--15 of FIG. 14. FIG. 16 is a partially cut-away plan view of the reversing mechanism utilized to return the workpiece transfer mechanism to its initial position following a transfer operation.
17 is a cross-sectional view taken along line 17-17 of FIG. 16, and FIG. 18 is a cross-sectional view taken along line 18-18 of FIG. 7, illustrating the hydraulic fluid cooling system. 10... Vacuum furnace, 12... Charging station,
14... Heating chamber, 16... Quenching station, 1
8... Sending station, 20... Base, 28
...body, 32 ... tubular door frame, 38 ... intermediate connection part, 42 ... charging platform, 44
...Door frame, 45...Slanted support, 46...
Horizontal support, 50... Charging track, 52... Roller, 53... Transport vehicle, 54... Processed parts, 56...
... Door device, 58 ... Door member, 66 ... Rod, 69,
70... Spaced bracket, 76... Drive shaft, 78... Hydraulic motor, 80... Link, 8
8, 90... spaced track sections, 92... workpiece transfer mechanism, 94... deflection drive spring, 98...
...Motor, 114...Drive pulley, 117...
Teeth, 118...Holding roller, 126...Shaft, 12
8... Swivel bracket, 138... Guide tube, 13
9... Groove, 140... Lever, 142... Motor shaft, 144... Pusher rod, 146... Groove, 148... Pin, 150... Pusher element,
152... Guide pipe, 175... Connecting rod, 176,
178...Limit stopper, 180...Roller, 1
84... Limit switch, 186... Inner door device, 188... Door member, 190... Inner body, 19
2...Outer body, 194...Inner inclined wall, 200...
... Connection part, 202 ... Door frame, 203 ...
... Door device, 204 ... Door member, 216 ... Heating element, 218 ... Terminal, 220, 222 ... Heat door, 228 ... Track portion, 229 ... Guide tube,
230... Track part, 233... Guide tube, 23
8...Fan, 240...Inner shell, 242...Outer shell, 244...Cooling space, 250...Hydraulic ram, 252...Piston, 254...Pulley, 2
56...Horizontal bar, 262...Spaced track member, 264...Elevator, 266...Frame, 268...Spaced track element, 270...
... Cable or chain, 271 ... Circulation fan, 272 ... Quenching liquid, 273 ... Motor, 2
74,276...orbital part, 277,278...
Guide pipe, 281... Unloading mechanism, 282... Drive spring, 283... Drive pulley, 284... Holding roller, 290... Loading rod, 292... Backward element, 294... Door frame , 296... Door device, 298... Door member, 302... Track portion,
304...Members spaced apart.

Claims (1)

[Scope of Claims] 1. A vacuum furnace for heat-treating processed parts in an environment below atmospheric pressure in a heating chamber of the furnace, comprising: a housing forming the heating chamber; a housing located in front of the heating chamber; a charging station for receiving the workpiece before transporting the workpiece to the heating chamber; a quenching station communicating with the heating chamber; a delivery station communicating with the quenching station; from the charging station into the heating chamber; means for transporting said workpiece and means for transporting said workpiece from said heating chamber to said quenching station and delivery station, sealing communication between adjacent stations during processing of said workpiece in said furnace; The door device includes a fixed frame forming an opening for communication between the stations, a plate-like door member attached to open and close the opening of the frame, and the door A sealing member is provided on the inner surface of the member adjacent the edge thereof, the sealing member being adapted to seal the door member to the frame when the door member is in the closed position. comprising door drive means for sealing against a sealing surface and connected to said door member for simultaneously moving said door member from a closed and sealed position to an open upper horizontal position by vertical and rotational movement; wherein the door member and the sealing member attached thereto face upwardly and away from the interior of the heating chamber, and the outer surface of the door member faces downwardly and is exposed to high temperatures emanating from the interior of the heating chamber. On the other hand, a continuous heat treatment vacuum furnace in which the door member itself forms a buffer for the sealing member. 2. A drive member in which the door drive means is mounted for rotation on the frame, a link member interconnecting the drive member to the door member, gear means interconnecting the drive member to the door member, and the door member. 2. A vacuum furnace as claimed in claim 1, including actuating means for rotating said drive member to raise and pivot the vacuum furnace from a sealed position to an open position. 3. A rod is rotatably attached to the other surface of the door member, and the link member is fixed to the rod so that rotation of the drive member causes the rod and the door member to move together with the link member. I can do it,
the gear means interconnecting a first gear attached to and fixed to the drive member, a second gear attached to and fixed to the rod, and the first and second gears; and a chain operable to cause pivoting movement of the door member when the door member is lifted by the drive member and the link member coupled thereto.
Vacuum furnace as described in section. 4 The ratio of the diameters of the first gear to the second gear is 2:
1, the first gear is fixed to the housing and the second gear is fixed to the door member, such that rotation of the drive member is controlled when the door member moves from a closed position to an open position. 4. The vacuum furnace according to claim 3, wherein the door member is not only raised but also rotated. 5. A patent comprising a series of tracks located in spaced relation to said charging station, heating chamber, cooling station and delivery station, and a carrier for placing said workpiece for advancement on said tracks. A vacuum furnace according to claim 1. 6. said transfer means comprises an elongate flexible drive spring connected at its end to the transfer element, means for engaging said spring to produce linear movement of said drive spring, means for rotating said gear means, and a positive 6. A vacuum furnace as claimed in claim 5, including means for urging said spring into intimate engagement with said gear means to create a positive drive therebetween. 7. The vacuum of claim 6, wherein said propulsion means includes a roller configured to engage said drive spring to urge said spring into intimate contact with said gear means. Furnace. 8 a pawl fixed to the outermost end of the transfer element, a guide tube disposed concentrically with the transfer element coupled to a drive spring located in and extending into the charging station; 10. A transfer element which is adapted to receive a transfer element located at said charging station during a transfer movement of a transport vehicle, said pawl being engageable with said transport vehicle and causing movement of the transport vehicle upon linear movement of said drive spring. The vacuum furnace according to item 6. 9 the guide tube has a longitudinally extending slot;
9. A vacuum furnace as claimed in claim 8, wherein it receives said pawl during transfer operations of said vehicle. 10 pressing the drive spring against the gear means so that the carrier can be moved forward of the pawl and into the charging station prior to actuation of the transfer of the carrier into the heating chamber; means for pivoting the roller downwardly against the drive spring to temporarily hold the roller in a position such that the transfer element and the drive spring coupled thereto move the vehicle; 9. The vacuum furnace according to claim 8, which is movable in a straight line. 11 comprising means for reversing the rotation of said means for rotation in accordance with a predetermined linear movement of said drive spring, whereby said drive spring is activated in preparation for transferring another vehicle to said heating chamber; 9. A vacuum furnace according to claim 8, wherein the vacuum furnace is retracted to its initial position. 12. said means for reversing includes a switch electrically interconnected with said means for rotating, an elongated bar engageable with said switch means in response to linear movement of a drive spring for transferring the vehicle to the heating chamber; 12. A vacuum furnace as claimed in claim 11, wherein the operation of said rotation means is reversed, thereby retracting said transfer element in preparation for the next conveyance operation. 13 an elongate tubular housing for receiving the drive spring therein extends downwardly from the charging station parallel to the elongate bar, the spring in the tubular housing being movable therein during the transfer operation and for the rotation 13. A vacuum furnace as claimed in claim 12, operable to effect a reversal operation of the means. 14 a second elongate drive spring, the transfer means being able to extend into the cooling station and heating chamber; a second elongate drive spring engaged with the second drive spring to effect linear movement of the second drive spring; gear means for driving the second gear means to produce a linear movement of the second drive spring, the second rotation means for rotating the workpiece following the heating operation; 7. A vacuum furnace as claimed in claim 6, wherein the vacuum furnace is operable to pull a conveyor carrying a carrier from said heating chamber to a quenching station and, after cooling, to said delivery station. 15 a quench tank in which the quench station forms a liquid reservoir located below the track;
an elevator having a track section mounted thereon to receive a vehicle thereon; means for securing said vehicle on said track section in response to lowering of said elevator into a liquid sump section of said quench tank; ,
Claims 1 and 2 include hydraulic operating means interconnected to said elevator for producing vertical movement of said elevator, and means in a liquid reservoir for circulation of quench liquid within said liquid reservoir during a quench operation. Vacuum furnace according to item 5. 16 including a chain interconnecting the elevator to the hydraulic operating means, the chain being fixed at one end to the housing and at the other end to the top of the elevator, thereby controlling the fluid in the hydraulic operating means; 16. The vacuum furnace of claim 15, wherein vertical movement of the pressure ram causes a corresponding movement of the elevator. 17. the housing includes an inner tubular shell and an outer shell having a rectangular shape in cross section, the inner shell being located within the outer shell, and the outer shell forming a cooling jacket around the inner shell; cooling fluid is thereby circulated between them, the corners of the space defined by said inner and outer shells having longitudinally extending plates therein for hydraulic fluid cooling. Claims 1 and 2 include means for continuously circulating, with heat exchange, a hydraulic fluid used to form a cooling space and operate various motors associated with the furnace, through said cooling space. Vacuum furnace according to item 1. 18 each of said tracks having a pair of spaced apart opposing members, a spacer disposed between said spaced members to locate said spaced position, and said track member intermediate said spacers; a plurality of wheel assemblies mounted thereon, each said wheel assemblage including a roller mounted on a pin extending along an axis thereof, the pin being mounted in opposing recesses of opposed members in fixed relation; 6. A vacuum furnace according to claim 5, wherein the roller is rotatably mounted with respect to said member.