JPH03257119A - Roller hearth type vacuum furnace - Google Patents

Abstract

PURPOSE:To decrease the generation of the unequal cooling and distortion of a work by rotating the work together with a turn table around a perpendicular axial line in a cooling chamber and cooling the entire circumference of the side face thereof with the cooling gases ejected from stationary nozzles. CONSTITUTION:The work W subjected to a heating treatment in heating chambers 12a, 12b, 12c of an annealing furnace 1 is charged by transporting rollers 51 onto the turn table 50 in the cooling chamber 13 and the turn table 50 is rotated at a low speed around the perpendicular axial line by an electric motor 54. On the other hand, a circulating fan 37 is run to suck the gaseous N2 in the cooling chamber 13 and to blast the gas toward the nozzles 40 in a circulating path 38. The gases which are deprived of heat and cooled in a heat exchanger 39 are ejected via plural pieces of the nozzles 40 into the cooling chamber 13. The ejected cooling gases collide against the side faces of the work W rotating together with the turn table 50, thereby cooling the work W. The cooling of the work W is thus nearly uniformly executed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a roller hearth type vacuum furnace that heats a workpiece in a vacuum state.

[Conventional technology]

In roller hearth type vacuum furnaces, in order to sinter and heat treat the workpieces such as metal materials, a cooling chamber is installed on the exit side of the heating chamber that heats the workpieces in a vacuum state to cool the workpieces with cold air. It is common to have a separate room.

As a device for this cooling, as shown in FIG. 8, a circulation fan 82 is provided at the top of the cooling chamber 81 in a downward direction. A configuration in which the cooling gas is cooled by the heat exchanger 84 and then circulated from the side of the object W to the circulation fan 82 is often used. Note that 85 is an outlet of the cooling chamber, and 86 is a heating chamber for heating the workpiece W in a vacuum state.

[Problem to be solved by the invention]

However, in the conventional cooling method described above, since the cooling gas is only blown from the top surface of the workpiece W, it is difficult to uniformly cool the workpiece, and distortion occurs in the workpiece due to uneven cooling. Interference occurred between the gas blown onto the object to be treated and the gas flowing back upward along the furnace side wall, resulting in a decrease in cooling efficiency and a waste of power in the circulation fan 82.

This invention solves the above-mentioned conventional problems, and aims to provide a roller hearth type vacuum furnace that can uniformly cool a workpiece.

[Means for Solving the Problems] A roller hearth type vacuum furnace according to the first invention of this application is a roller hearth type vacuum furnace in which a cooling chamber is provided on the exit side of a heating chamber for heating a workpiece in a vacuum state. A rotary table is provided with multiple nozzles that eject cooling gas on the side of the workpiece conveyance path in the cooling chamber, and has a conveyance roller on the top surface for conveying the workpiece and is driven to rotate around a vertical axis. is provided in the cooling chamber, and the cooling gas ejected from the nozzle is sprayed onto the workpiece transported from the heating chamber and placed on the rotary table.

The roller hearth type vacuum furnace of the second invention of this application is cooled on the exit side of the heating chamber where the workpiece is heated in a vacuum state!
In a roller hearth type vacuum furnace equipped with a hollow main shaft that penetrates the top of the furnace body of the cooling chamber and is driven to rotate around a vertical axis, the roller hearth type vacuum furnace is provided with a plurality of nozzles are installed, an exhaust port provided in the furnace body and the main shaft are connected by a gas circulation path, and a blower for gas circulation and a heat exchanger for cooling the gas are provided in the gas circulation path, A feature of the present invention is that the cooling gas ejected from the nozzle is sprayed onto the workpiece that has been transported from the heating chamber and placed on a transport roller in the cooling chamber.

(Function) In the roller hearth vacuum furnace of the first invention, the workpiece charged into the cooling chamber is placed on the rotary table, rotates together with the rotary table around the vertical axis, and is ejected from the nozzle. As the cooling gas rotates, the cooling gas sequentially impinges on the entire circumference of the side surface of the workpiece, so that the workpiece is cooled almost uniformly.

Further, in the roller hearth type vacuum furnace of the second invention, the workpiece loaded into the cooling chamber and placed on the conveying roller is cooled by the cooling gas ejected from the nozzle that rotates around the vertical axis together with the main shaft. As the nozzle rotates, this cooling gas sequentially impinges on the entire circumference of the side surface of the object to be processed, so that the object to be processed is cooled almost uniformly.

(Embodiment) A first embodiment, which is an embodiment of the first invention, will be described below with reference to FIGS. 1 to 4.

In the figure, 1 is a sintering furnace which is an example of a roller hearth type vacuum furnace, 2 is a furnace body, 3 is an inlet for charging a workpiece, and 4 is an outlet for taking out the same. 5 is the door of entrance 3, 6 is the door of exit 4
The doors are driven up and down by lifting devices 7 and 8, respectively. Further, the furnace body 2 is roughly divided into three parts by partition walls 9 and 10, and inside thereof there are a vacuum standby chamber 11, a heating chamber 12a which is a dewaxing chamber, a heating chamber 12b which is a sintered seedling chamber, and an aging treatment chamber. A heating chamber 12c and a cooling chamber 13 are formed. Each heating chamber 12a to 12C
(hereinafter collectively referred to as the heating chamber 12, and the other parts are also collectively referred to in the same manner) is surrounded on all four sides by a heat insulating wall 14 made of graphite, and its population 15 and outlet 16 are respectively opened and closed by n17. ing. Reference numeral 18 denotes an opening/closing device for the door 17, which connects the frame 19, which is guided so as to be raised and lowered by a guide (not shown) fixed to the furnace body 2, to the piston rod of the air cylinder 20, and connects the frame 19 via a parallel link 21 to the piston rod of the air cylinder 20. It is made by connecting f117. The door 17, whose lower end abuts a stopper (not shown), seals the inlet 15 and the outlet 16 by lowering the frame 19 further, and by pulling up the frame 19, the door 17 is separated from the inlet 15 and the outlet 16 and then moved upward. It is now possible to be raised to 22 is the heating chamber 12
This is a heating device consisting of an electric heater installed inside. Also 2
3 is a conveyance roller provided in the furnace body 2, which is a roller made of heat-resistant metal that is rotationally driven by a known drive mechanism;
A workpiece transport path 24 extending from the inlet 3 to the outlet 4 is formed above the transport row 523 .

On the other hand, the cooling chamber 13 has a partition wall 31 made of metal plates and a side wall 32.
32 and a ceiling wall 33, and an entrance 34 provided in the partition wall 31 is opened and closed by a door 35. This i'i35 is opened and closed in the same manner as the door 17 by the opening/closing device W118. 36 is the ceiling 133
A circulation fan 37 is provided directly above the exhaust port 36. Further, 38 is a circulation path formed between the furnace body 2 and the wall body 30, and 39 is a cooling heat exchanger provided within this circulation path 38 to cross the gas flow. 4
Reference numeral 0 designates a number of nozzles for ejecting cooling gas provided on the side wall 32, with their ejection ports directed into the cooling chamber 13 and in a substantially horizontal direction. Further, the arrangement of the nozzles 40 is as shown in FIG.
1 are arranged in multiple rows (5 rows in this example), but the nozzle positions of adjacent nozzle rows 41 and 41 are slightly shifted in the vertical direction, and the nozzle rows 41 and 41 are arranged horizontally as shown by the chain line 42 in FIG. The nozzle centers are arranged on a straight line that is slightly inclined with respect to the direction.

Reference numeral 50 denotes a rotary table, which has conveyance rollers 51 on its upper surface, a support shaft 52 protruding from its lower surface, which is rotatably supported around a vertical axis by a bearing 53 provided at the bottom of the furnace.
4. The configuration is such that it is rotationally driven by 4. Further, the conveying roller 51 is rotatably driven by a driver 55 equipped with a brake attached to the rotary table 50 so that the object to be processed W can be conveyed.

To perform a vacuum sintering process in the sintering furnace 1 having the above configuration, the workpiece W charged from the inlet 3 is made to wait in the vacuum waiting chamber 11, and then dewaxed in vacuum in the heating chamber 12a. The material is sintered in a vacuum state in the heating chamber 12b, then kept at high temperature for a predetermined time in the heating chamber 12C for aging treatment, and then charged into the cooling chamber 13 through the inlet 34 to be cooled. At this time, when the workpiece W reaches the rotating table 50, the conveying roller 51 is stopped, and the electric motor 5
4 rotates the turntable 50 around the vertical axis at low speed. On the other hand, the circulation fan 37 is operated to suck up gas (for example, N2 gas) in the cooling chamber 13 and blow it through the circulation path 38 toward the nozzle 40. At this time, the gas is removed by passing through the heat exchanger 39. It is thermally cooled and ejected from each nozzle 40 into the cooling chamber 13 as a low-temperature cooling gas. This ejected cooling gas is transferred to the workpiece W rotating together with the rotary table 50.
The object to be processed W is cooled. As the workpiece W rotates, the angle at which the cooling gas from each nozzle 40 collides with each part of the workpiece W changes sequentially, and the rotation of the workpiece W changes sequentially.
Since the cooling gas sequentially collides with the entire circumference of the side surface, the object to be processed W is cooled almost uniformly with little uneven cooling. In particular, in this embodiment, the adjacent nozzle rows 4
Since the vertical positions of the nozzles 1 and 1 are shifted, the rotating workpiece W is passed through a large number of nozzles 40 with exactly fine vertical pitches.
This results in a cooling effect similar to that achieved by cooling, and a more uniform cooling effect can be obtained.

Further, since the cooling gas circulation path is partitioned by the wall 30, interference between the gases before and after colliding with the object to be processed is prevented, and smooth and efficient cooling is performed.

After cooling for a predetermined time as described above, the rotary table 50 is stopped, the conveying rollers 51 are driven to send the workpiece W out of the furnace from the outlet 4, and the same process is repeated.

In the sintering furnace 1 having the above configuration, the sintered crystal (with a diameter of 30 am and a length of 100 mm) obtained by sintering in the heating chamber 12 (
The workpieces W made up of 150 pieces of material 5LJS410L) placed in a tray were heated to 1200°C in the heating chamber 1.
Charge the cooling chamber 13 from 2G, and the rotation speed of the turntable 50:
When the crystals were cooled for 60 minutes under the following conditions: 5 rpm, cooling gas (N2) temperature: 50°C, and circulating air flow rate = 150/min, the strain of the fired crystal was 0.02 (average value). Ta. On the other hand, as a comparative example, a sintering furnace having the cooling chamber 81 shown in FIG.
When cooling was performed, the strain of the fired crystal was 0.15 (
average value).

Next, a second embodiment, which is an embodiment of the second invention, will be described with reference to FIGS. 5 to 7.

In the figure, the same parts as in FIG. 1 are given the same reference numerals, and the structure of the furnace on the furnace inlet side from the heating chamber 12G is the same as in FIG. 1. Reference numeral 61 denotes a cylindrical main shaft made of heat-resistant steel, which passes through the top of the furnace body 2 and is connected to the cooling chamber 13 by a bearing 62 attached to the furnace body 2.
It is rotatably supported around a vertical axis passing near the center of. 63 is an electric motor installed on the furnace body 2, and the main shaft 6
1 to drive the chain. 64 is the main shaft 61
This is a rotary joint that fits into the upper end of the

- Man 65 is a nozzle support tube made of heat-resistant steel that is connected to the lower end of the main shaft 61, which includes a main pipe 66 whose middle part is connected to the main shaft 61 and extends in the horizontal direction, and a curved tubular shape connected to both ends of this main pipe 66. It consists of a branch pipe 67 and a branch pipe 68 whose upper end is connected to the branch pipe 67 and whose lower end is sealed. Main shaft 6
1. The main pipe 66, the branch pipe 67, and the branch pipe 68 have internal hollow portions that communicate with each other. When the main shaft 61 is in a stopped state, each branch pipe 68 is located at a side position of the workpiece transport path 24 so as not to collide with the workpiece W being transported. A plurality of nozzles 69 are provided which face the object to be processed W and have ejection ports extending in a substantially horizontal direction. Further, the arrangement of these nozzles 69 is such that the positions of the nozzles provided on adjacent branch pipes 68, 68 are slightly shifted in the vertical direction, as in the previous embodiment. Further, in FIG. 7, 71 is an exhaust port provided in the furnace body 2, and a gas circulation path 72 for circulating cooling gas is provided between the exhaust lower 1 and the fixed pipe portion of the rotary joint 64 at the top of the furnace. Connected, 73
is a blower provided in the gas circulation path 72, and 74 is a heat exchanger for cooling the gas.

In the sintering furnace 75 having the above configuration, after the workpiece W is charged into the cooling chamber 13 from the outlet 16 of the heating chamber 12C, the workpiece W is stopped on the conveying roller 23, and the main shaft 61 is stopped by the electric motor 163. And the nozzle support tube 65 integrated therewith is rotated at low speed around the vertical axis. On the other hand, the blower 73 is operated to suck the gas in the cooling chamber 13 and the gas circulation path 72
Air is blown inside toward the rotary joint 64, and at this time, the gas is cooled by absorbing heat by passing through the heat exchanger 74.

The obtained low-temperature cooling gas passes through the main shaft 61, the nozzle support tube 65, and is ejected from each nozzle 69 into the cooling chamber 13. Since each nozzle 69 rotates around the workpiece W, the cooling gas from each nozzle 69 is rotated around the workpiece W.
The angle at which the cooling gas collides with each part changes sequentially, and the cooling gas collides sequentially with the entire circumference of the side surface of the workpiece W.
The object W to be processed is cooled almost uniformly with little uneven cooling. The gas whose temperature has increased due to collision with the object to be processed is exhausted from the exhaust lower 1.
The gas then passes through the gas circulation path 72, is cooled, and is again circulated and supplied into the furnace.

After cooling for a predetermined time as described above, the main shaft 61 is stopped, the conveyance rollers 23 are driven to send the workpiece W out of the furnace, and the same steps are repeated.

In the sintering furnace 75 having the above configuration, cooling treatment was performed on the same workpiece W as in the first embodiment under the same conditions (however, the rotation speed of the main shaft 61: 5 ROM), and the strain of the sintered crystal was 0. 015 Mm (average value).

The present invention is not limited to the above embodiments; for example, the nozzle 40 of the first embodiment
Instead of providing the wall 32 on the side wall 32, a plurality of nozzles 40 for each nozzle row 41 are provided on the pipe wall of a pipe material extending in the vertical direction as in the second embodiment. A plurality of them may be arranged in parallel, and the gas drawn from the cooling chamber 13 to the outside of the furnace body 2 may be cooled by a heat exchanger, and then supplied to the pipe material and ejected into the cooling chamber. Also the second
Instead of the nozzle support tube 65 in the embodiment, a flat wind box-shaped nozzle support whose side surface faces the object to be processed is used,
A plurality of nozzles 69 may be provided here. Also nozzle 40. ? As i and 69, those having slit-like openings that are continuous in the vertical direction may be used.

Furthermore, an auxiliary nozzle may be provided for spraying cooling gas onto the object to be processed from above or below.

The present invention can also be applied to roller hearth type vacuum furnaces of various uses and structures other than sintering furnaces.

〔Effect of the invention〕

As explained above, according to the present invention, in the cooling chamber, the workpiece rotates around the vertical axis together with the rotary table, and the entire circumference of the side surface of the workpiece is cooled by the cooling gas ejected from the fixed nozzle (the first invention), or the entire circumference of the side surface of the stopped workpiece is cooled by the cooling gas jetted from a nozzle that rotates around the vertical axis together with the main shaft (second invention), thereby reducing uneven cooling of the workpiece. and the generation of distortion associated with it is reduced.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of a sintering furnace showing a first embodiment of the present invention, Fig. 2 is a sectional view taken along A-AI in Fig. 7, and Fig. 3 is the same <B
-B sectional view, Figure 4 is a C-C sectional view of Figure 3,
The figure is a longitudinal sectional view of the cooling chamber portion of a sintering furnace showing a second embodiment of the present invention, FIG. 6 is a sectional view taken along line D-D in FIG. 5, and FIG. 7 is a sectional view taken along line E-E of the same < , FIG. 8 is a longitudinal sectional view of a cooling chamber portion showing an example of a conventional sintering furnace. DESCRIPTION OF SYMBOLS 1... Sintering furnace, 2... Furnace body, 11... Vacuum standby chamber, 12a-12G... Heating chamber, 13... Cooling chamber, 2
2... Heating device, 23... Conveyance roller, 24...
・Workpiece conveyance path, 30... wall, 32... side wall,
37...Circulation fan, 38...Circulation path, 39...
Heat exchanger, 40... Nozzle, 50... Turntable, 51
... Conveyance roller, 52 ... Support shaft, 53 ... Bearing, 54 ... Electric motor, 55 ... Drive machine 61 ... Main shaft, 62 ... Bearing, 63 ... Electric motor, 64... Rotary joint 1.65... Nozzle support tube, 68...
... Branch pipe, 69 ... Nozzle, 71 ... Exhaust port, 72
... Gas circulation path, 73 ... Blower, 74 ... Heat exchanger, 75 ... Sintering furnace. 50 30 0 8 Figure 5 6th Box 7

Claims (1)

[Scope of Claims] 1. In a roller hearth vacuum furnace in which a cooling chamber is provided on the exit side of a heating chamber that heats a workpiece in a vacuum state, a cooling chamber is provided on the side of a workpiece transport path in the cooling chamber. A rotary table having a plurality of nozzles for ejecting gas, and having a conveyance roller on the upper surface for conveying the workpiece and being driven to rotate around a vertical axis is provided in the cooling chamber, and the workpiece is conveyed from the heating chamber. A roller hearth type vacuum furnace characterized in that cooling gas ejected from the nozzle is blown onto the workpiece placed on the rotary table. 2. In a roller hearth vacuum furnace that heats the workpiece in a vacuum and has a cooling chamber on the exit side of a heating chamber, the roller hearth is driven to rotate around a vertical axis through the top of the furnace body of the cooling chamber. A plurality of nozzles arranged on the side of the workpiece conveyance path in the cooling chamber are attached to the hollow main shaft, and the exhaust port provided in the furnace body and the main shaft are connected by a gas circulation path. A blower for gas circulation and a heat exchanger for cooling the gas are provided in the circulation path, and the cooling air jetted from the nozzle onto the workpiece transported from the heating chamber and placed on the transport roller in the cooling chamber. A roller hearth vacuum furnace characterized by blowing gas.