JP2002372373A - Vacuum furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum furnace in which maintenance frequency can be decreased as much as possible by preventing scattering of wax, metal vapor, or the like, while ensuring efficient exhaustion. SOLUTION: An enclosed container V comprises a tray 3 for carrying an article M, and a semi-container cover 4 being applied to the tray 3. The tray 3 is provided with an exhaust opening 31 which is interconnected with an opening at the forward end 51 of an evacuation pipe 5 by advancing it toward the enclosed container V through a drive cylinder 56. The cover 4 is provided with a gas conduction hole 42 for feeding gas in the furnace into the enclosed container V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vacuum furnace, and more particularly to a vacuum furnace suitable for forming a dewaxing chamber, a degassing chamber, and the like of a vacuum sintering furnace.

[0002]

2. Description of the Related Art In a continuous vacuum sintering furnace, a transfer mechanism such as a transfer roller transfers a dewaxing chamber, a degassing chamber, a sintering chamber, and a cooling chamber from a front chamber for isolating the atmosphere from the inside of the furnace. The object is continuously transported. In the dewaxing chamber and the degassing chamber, the objects to be processed are, for example, 600 ° C.
While heating to about 00 ° C., vacuum evacuation is performed to perform dewaxing and degassing. In the sintering chamber, the object to be processed is heated to, for example, about 1400 ° C. while evacuating to sinter.

[0003]

In the above-mentioned conventional continuous vacuum sintering furnace, an object to be processed is placed on an open tray or the like for efficient heating, and each chamber is exposed. In the dewaxing chamber and the degassing chamber, there is a problem that wax and metal evaporate evaporated from the processing object adhere to the furnace wall and the like, and the maintenance frequency of the furnace increases in order to remove them. . Further, there is also a problem that the wax and the metal evaporate adhering to the furnace wall and the like evaporate again and adhere to the object to be processed, thereby deteriorating the quality.
Further, dewaxing and degassing of the object to be treated while the entire furnace having a large volume is evacuated has a problem that the exhaust efficiency is low.

Accordingly, the present invention has been made to solve such a problem, and a vacuum furnace capable of preventing scattering of wax and metal evaporates, thereby reducing the frequency of furnace maintenance and performing efficient exhaust. The purpose is to provide.

[0005]

According to a first aspect of the present invention, an exhaust port (31) communicating with the inside of a container is provided.
A closed container (V) that accommodates the object to be treated (M) and is carried into the furnace, and a vacuum exhaust pipe (5) is advanced toward the closed container (V) to open the front end opening thereof. Exhaust holes (3
Exhaust pipe driving means (56) for communicating with 1).

In the first aspect of the present invention, it is only necessary to evacuate the inside of the closed container having a small volume containing the object to be processed, instead of exhausting the entire interior of the furnace. Since the evaporant from the processed material is exhausted without dissipating from inside the closed container, the evaporate adheres to the furnace wall, etc., and frequent maintenance is required. It does not reattach to the object and cause quality deterioration.

[0007] In the second invention, the closed container (V) includes:
A gas flow hole (42) for letting gas in the furnace flow into the closed vessel (V) is provided. In the second aspect of the present invention, since the nitrogen gas or the like introduced into the furnace forms a flow that flows from the furnace through the gas flow holes into the closed vessel, the wax or metal vapor separated and evaporated from the object to be processed is formed. Etc. are reliably prevented from scattering into the furnace, and are quickly discharged through the vacuum exhaust pipe.

In the third invention, the closed container (V) is
Tray (3) for transporting the workpiece, and the tray (3)
And a semi-container-shaped lid (4) covered with the cover. In the third aspect of the present invention, the closed container can be easily realized by using the transport tray and covering the cover with the lid.

The reference numerals in parentheses indicate the correspondence with the specific means described in the embodiments described later.

[0010]

(First Embodiment) FIG. 1 shows an example in which the vacuum furnace of the present invention is used in a degassing chamber of a vacuum sintering furnace.
Openings provided at both ends of the cylindrical chamber wall of the degassing chamber 1 are closed by airtight doors 12 and 13. Each of the airtight doors 12 and 13 is connected to an operator 22 at the tip of a rod 21 extending downward from the drive cylinders 2A and 2B by a parallel link 23, and is opened as the operator 22 rises. A large number of transport rollers 14 are arranged at regular intervals from the dewaxing chamber AF in the preceding stage to the sintering chamber BF in the subsequent stage via the degassing chamber 1, and the workpieces M loaded on the tray 3 are transported by the transporting rollers 14. And is carried into the degassing chamber 1. Tray 3
Is covered with a rectangular semi-container-shaped lid 4 which is approximately the same size and is opened downward, and the opening edge flange 41 of the lid 4 is in contact with the outer peripheral edge of the tray 3 to cover the workpiece M. This constitutes a container V. The lid 4 has gas circulation holes 42 formed in the front and rear (left and right in FIG. 1) side walls.
Is provided with an exhaust hole 31 at the center. Transport roller 1
Numeral 4 is made of a carbon fiber composite material having excellent heat resistance, and stops rotating and stands still with the tray 3 positioned at substantially the center of the degassing chamber 1.

In the degassing chamber 1, a chamber wall 11 and an airtight door 12,
A heat insulating wall 15 is provided on the inner side along the inner surface of 13, and a heater 16 is provided inside the upper and lower heat insulating walls 15. In addition, an upper heat insulating wall 15 is provided on the top wall of the degassing chamber 1.
The base end of a gas injection pipe 45 penetrating downward is fixed, and a nitrogen gas pipe 46 is connected to the gas injection pipe 45.

An evacuation pipe 5 is provided through the center of the bottom wall of the degassing chamber 1, and the evacuation pipe 5 penetrates the lower heat insulating wall 15, and an upper end 51 is provided with an evacuation hole 31. Tray 3
Is in contact with the lower surface of the center of the. Thereby, the vacuum exhaust pipe 5
The upper end 51 is opened to the exhaust hole 31. The lower end 52 of the vacuum exhaust pipe 5 is bent at a right angle in the horizontal direction outside the degassing chamber 1, and is connected to an exhaust main pipe 54 via a bellows 53. The exhaust main pipe 54 leads to an unillustrated vacuum exhaust device. The evacuation pipe 5 penetrates a flange 55 that keeps airtight and slidably holds the pipe vertically.
The lower end 52 of the vacuum exhaust pipe 5 is the rod 5 of the drive cylinder 56.
It is connected to the upper end of 61 and is supported by it.

When the degassing process is performed in the degassing chamber 1, the airtight door 12 is opened and the transport rollers 14 are opened.
As a result, the processing object M accommodated in the closed container V is carried into the degassing chamber 1 from the dewaxing chamber AF. At this time, the vacuum exhaust pipe 5 is lowered by the driving cylinder 56 to a position lower than the transport roller 14 which does not interfere with the tray 3. When the closed container V is positioned at a predetermined position in the degassing chamber 1, the vacuum exhaust pipe 5 is raised, and the opening edge of the upper end 51 comes into contact with the periphery of the exhaust hole 31 on the lower surface of the tray 3 (see FIG. 1). (State) The vacuum exhaust pipe 5 and the inside of the closed vessel V communicate with each other through the exhaust hole 31.

Thereafter, the heater 16 is energized to supply the workpiece M
Is heated to a predetermined temperature (about 1000 ° C.), and the inside of the closed container V is exhausted while supplying a predetermined amount of nitrogen gas from the gas supply pipe 45 to perform degassing processing. At this time, the closed vessel V having a small volume is efficiently exhausted, and a flow of nitrogen gas flowing from the chamber of the degassing chamber 1 into the closed vessel V through the gas circulation holes 42 is formed. The metal vapor separated and evaporated from M is quickly discharged through the vacuum exhaust pipe 5 without being scattered into the degassing chamber. As a result, an efficient degassing process is performed, and the metal vapor evaporated from the processing target M adheres to a chamber wall or the like, which requires frequent maintenance or lowers the quality of the processing target M. The problem is solved. When the degassing process is completed, the vacuum exhaust pipe 5 is lowered, the hermetic door 13 is opened, and the workpiece M accommodated in the closed container V is sent to the subsequent sintering chamber BF by the transport roller 14.

(Second Embodiment) When the tray lifting device 7 as shown in FIG. 2 is further provided in the degassing chamber 1 having the structure shown in the first embodiment, the conveyance roller 14 can be oscillated. That is, in FIG. 2, a drive cylinder 71 is further provided on the bottom wall of the degassing chamber 1, and a support base 72 is fixed to the tip of the rod 711.
The upright frame 721 of the support base 72 extends above the transport roller 14 through the heat insulating wall 15, contacts the lower surface of the tray 3, and lifts the tray 3 upward away from the transport roller 14. The opening of the upper end 51 of the vacuum exhaust pipe 5 is in contact with the lower surface of the tray 3, and exhausts the inside of the closed container V through the exhaust hole 31. Thereby, oscillation of the transport roller 14 is possible.

The upright frame 721 of the support base 72 is normally lowered at the upper end thereof to a position lower than the conveying roller 14, and the object M accommodated in the closed container V is degassed by the conveying roller 14. When it is carried into the chamber 1 and positioned, the upright frame 721 (that is, the support base 72) is raised while lifting the tray 3 as shown in FIG. The vacuum exhaust pipe 5 is raised with respect to the lifted tray 3 so that the opening of the upper end 51 is brought into contact with the lower surface of the tray 3, and the inside of the closed container V is evacuated.

(Other Embodiments) n Although the gas circulation holes 42 are not essential in each of the above-described embodiments, it is possible to reliably prevent the evaporated metal from flowing back into the degassing chamber 1 by forming a flow of nitrogen gas. It is preferable to provide at this point. Further, the vacuum exhaust pipe 5 does not necessarily need to be in contact with the tray 3, and an exhaust hole 31 is provided on the lid 4 side, and the vacuum exhaust pipe 5 is connected to the lid 4.
It is good also as a structure made to contact communication. In each of the above embodiments, the case where the vacuum furnace of the present invention is used as a degassing chamber of a continuous vacuum sintering furnace is described. However, the present invention can also be used in a batch type, and is not limited to degassing. Can be applied to In addition, it is a matter of course that the transport of the workpiece is not limited to the transport roller.

[0018]

As described above, according to the vacuum furnace of the present invention, the frequency of furnace maintenance can be reduced by preventing scattering of wax and metal evaporation, and efficient exhaust can be performed.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of a vacuum furnace showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a vacuum furnace showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Degas chamber, 11 ... Chamber wall, 3 ... Tray, 31 ... Exhaust hole, 4 ... Lid, 5 ... Vacuum exhaust pipe, 51 ... Upper end, 56 ... Drive cylinder, M ... Workpiece, V ... Closed container .

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K018 DA04 4K055 AA05 GA01 4K061 AA05 BA02 BA09 CA08 CA21 DA05 GA04 4K063 AA06 AA07 AA16 CA05 CA06 DA19

Claims (3)

[Claims] An exhaust hole communicating with the inside of a container is provided, a closed container for containing an object to be treated and carried into a furnace, and an evacuation pipe is advanced toward the closed container to open the front end opening thereof. A vacuum furnace comprising an exhaust pipe driving means communicating with an exhaust hole. 2. The vacuum furnace according to claim 1, wherein the closed vessel is provided with a gas flow hole through which gas in the furnace flows into the closed vessel. 3. The vacuum furnace according to claim 1, wherein the closed container includes a tray for transporting the object to be processed, and a semi-container-shaped lid covered by the tray.