JPH0129215Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dewaxing device attached to a sintering furnace for sintering a powder molded product.

[Prior Art] As is well known, various sintered materials such as metals and ceramics are manufactured by molding raw material powder into a desired shape and then sintering it at a high temperature. Therefore, at the stage of first making powder molded products from raw powder, various organic auxiliaries (hereinafter collectively referred to as wax) are added to ensure the moldability of the powder particles, but on the other hand, in the sintering process, The mixed wax acts as a harmful substance that has various adverse effects on the sintered product. Therefore, before sintering a powder molded product, the wax contained in the molded product must be removed as a pretreatment. In recent sintering furnaces, the dewaxing process and the subsequent preliminary to main sintering processes are carried out in a single furnace as part of an integrated process to improve processing efficiency and thermal efficiency. Furthermore, this type of sintering furnace is usually equipped with a dewaxing device (wax trap tower) necessary for vacuum suction and recovery of the wax vapor generated from the powder molded product during the dewaxing process. be.

Conventionally, this dewaxing device has been constructed by interposing trap elements such as cooling fans, baffles, and other mechanical traps in a conduit through which gas containing wax vapor discharged from a sintering furnace flows. has been done. That is, when gas containing wax vapor is passed through the trap element, the wax dews and condenses on the surface of the trap element, thereby cooling and trapping the wax from the exhaust gas.

[Problems to be solved by the invention] However, such conventional devices suffer from insufficient dewaxing performance and complicated maintenance management.
It can be said that this has reached its practical limit. The details of these problems are as follows. First, from the standpoint of dewaxing performance, in the case of conventional devices, the trapping element inserted in the conduit loses its trapping ability as wax vapor adheres to the surface as it is used and as the temperature rises. In addition to this, it is necessary to keep the wax warm by using a heater around the outer circumference of the conduit to prevent wax from sticking to the inner wall.
Due to poor trapping efficiency, it is inevitable that a portion of the wax vapor will be sucked into the downstream exhaust system without being dewaxed. For this reason, currently the exhaust system is not equipped with a heat insulating heater just before the vacuum pump (vacuum pumps require water or air cooling for operation and cannot be kept warm up to the vicinity of their inlets, and if kept warm, wax vapor will build up inside the vacuum pump). (due to the circumstances in which wax reaches the pipe), there are frequent cases where wax vapor adheres to the inner wall of the pipe and accumulates, clogging the pipe.

In addition, in this conventional dewaxing device, cooling means and heating means for the trap element are attached or prepared, and the step of cooling the trap element and the step of melting and removing wax from the trap element every one to several charges are repeated. Coupled with the necessity of periodic removal of the wax clogging the piping, the maintenance and management of the apparatus body and the exhaust system becomes unbearable.

Based on this technical background, the present invention is designed to remove wax vapor from the exhaust gas by intervening in the exhaust system between the sintering furnace and the vacuum pump, and is far more effective than current methods. This new method is expected to have high trapping efficiency, and based on this, the problems of piping blockages and vacuum pump performance deterioration mentioned above can be prevented for a long time, and at the same time, maintenance and management are significantly simplified. The aim is to provide a new dewaxing device.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a cooling drum rotatably disposed in a dewaxing tank through which gas containing wax vapor flows, and a surface of the cooling drum. It is characterized in that a cutter for cutting the drum surface is attached to the drum.

[Function] With the dewaxing device having such a configuration, when the gas flowing in the dewaxing tank passes near the cooling drum, the wax vapor contained therein condenses and adheres to the surface of the cooling drum, while the wax adhering to the surface of the cooling drum is The wax is continuously cut and scraped off by a cutter attached to the drum, and is deposited as solid wax in the dewax tank. In other words, according to this cooling drum method, the cooling drum that traps the wax vapor is constantly forcedly cooled so that its trapping ability does not deteriorate, and the surface of the cooling drum is cut with cutters so that it is fresh and has no wax attached. Since the surface condition is updated and the trap is brought into contact with the circulating gas, the deterioration of trapping ability caused by temperature rise over time and wax adhesion on the surface, which is the case with conventional mechanical traps, is eliminated, resulting in excellent dewaxing. Performance is permanently maintained. On the other hand, the trapped wax can be immediately cut out from the cooling drum with a cutter and recovered from the dewaxing tank whenever necessary, which eliminates the troublesome conventional dewaxing process in which wax is heated and melted and then flowed out. No process is required.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an outline of an exhaust gas treatment system for a vacuum sintering furnace equipped with a dewaxing device according to the present invention, and this embodiment is intended to further improve the dewaxing performance of an existing dewaxing device (wax strap tower). In this case, a dewaxing device according to the present invention is added. Therefore, to explain the drawings, 1 is a vacuum sintering furnace (chamber), 2 is a tight box placed in the core part of this chamber 1, and inside the tight box is a target processed material (powder molded product) a. to store. This processed material a is heated by a heater 3 disposed around the outer periphery of the tight box 2 and subjected to a series of heat treatments. In the dewaxing step of dewaxing the material a, an inert gas (flow gas) is introduced into the chamber 1 from the introduction pipe 1a connected to the chamber 1, while
Vacuum suction is carried out into the tight box 2 from an exhaust pipe 2a directly connected to the tight box 2, and wax vapor evaporated from the processed material a is discharged to the outside together with the flow gas supplied into the chamber 1 without leaking. 4 is a line from the exhaust pipe 2a to an exhaust line 5a, a wax strap tower 6, and an exhaust line 5.
b. A vacuum pump for sucking and exhausting gas containing wax vapor from inside the tight box 2 via the dewaxing device 7 and the exhaust system line 5c.

First, the configuration of the conventional type wax strap tower 6 provided on the upstream side of the exhaust system will be explained. The wax strap tower 6 has a gas inlet 6a connected to the exhaust system passage 5a on one side of its lower part, and a gas outlet 6b connected to the exhaust system passage 5b on one side of its upper part. A vertical cylindrical conduit 6A, through which gas containing wax vapor discharged from the sintering furnace 1 flows upward, and trap elements interposed in multiple stages within the conduit 6A. 8. In this case, the trap elements 8 are specifically trap plates 8A each having a large number of ventilation holes 8a and partitioning the inside of the conduit 6A into a plurality of stages.
and trap pieces 8B, such as lashing rings, which are densely stacked on each trap plate 8A. In addition, this wax strap tower 6
A tape heater, which will be described later, is wound around its outer periphery, and an internal heater 9 is inserted through the conduit 6A. Further, w in the figure indicates the molten wax collected at the bottom of the conduit 6A.

Next, the dewaxing device 7 according to the present invention will be explained. This device 7 cools the gas discharged from the wax trap tower 6 (containing wax vapor that has not yet been completely trapped) into a dewaxing tank 10 through which it flows. A drum 11 is rotatably disposed, and a cutter 12 for cutting the surface of the drum is attached to one side of the cooling drum. The dewaxing tank 10 has a gas inlet 10a that is connected to the exhaust system path 5b on one side, and a gas outlet 10b that is connected to the exhaust system path 5c on the opposite side, and has an upper part that connects the two. The cooling drum 11 is housed in the inner space 10A, and the lower space 10B
The solid wax W cut from the cooling drum 11
It is used in the sedimentation tank of Note that an opening/closing door 10c is provided on one side of the lower space 10B for collecting the solid wax W at any time.
Further, the cooling drum 11 is disposed in the upper space 10A corresponding to the gas flow path in the dewaxing tank 10 so as to be rotatable in the direction of the illustrated arrow. The cooling drum 11 is formed into a hollow body, and water, liquid nitrogen, or other appropriate refrigerant is circulated inside the drum so that the drum surface 11s is constantly forcedly cooled. And this cooling drum 1
The cutter 12 is attached to one side of the lower part corresponding to the gas outlet 10b of the gas outlet 1 over the entire width thereof. The cutter 12 has its base end 12b pivotably supported within the dewax tank 10, and
A traction spring 13 for urging the cutter 12 toward the cooling drum 11 is suspended on the inner surface of the dewaxing tank 10,
The sharp cutting edge 12a is made to bounce against the drum surface 11s with an appropriate contact pressure.

A specific example of the structure of the cooling drum 11 disposed within the dewaxing tank 10 is shown in FIG. 2. That is, the cooling drum 11 includes a hollow drum body 11A, lids 11B at both ends, and a body 1.
The drum body 11A is constructed as an assembly of a drum shaft 11C that is penetrated into the drum body 1A, and the drum body 11A has a chain sprocket mechanism (driving sprocket 14, driven sprocket 15) attached to the shaft 11C.
and a chain 16) to be rotated by an external source electric machine. Refrigerant is supplied into the drum main body 11A from an inflow pipe 17 connected to the shaft 11C at one end through an inflow hole 18 in the shaft 11C, and a refrigerant is supplied into the drum main body 11A from an outflow hole 19 provided in the shaft 11C. The refrigerant inside is discharged to the outflow pipe 20, and the refrigerant is circulated within the drum body 11A, so that the drum surface 11s is constantly forcedly cooled from the inner side.

Note that the gas outlet 10 of this dewaxing device 7
As shown in the figure, a tape heater 21 for heat retention is wound around the outer periphery of the exhaust system paths 5a and 5b and the wax strap tower 6 up to the point 5b. Also, although not shown, the dewaxing tank 10
A guide member is provided inside the cooling drum 11 as necessary so that the gas introduced from the gas inlet 10a flows along the surface of the cooling drum 11. and,
The shape and size of the dewaxing tank 10 are designed based on the viewpoint that the gas flowing therein can come into contact with the drum surface 11s as effectively as possible.

Now, if the apparatus is equipped with the above-mentioned components, in the dewaxing process of the sintering furnace 1, the exhaust gas sucked from the sintering furnace 1 is first treated in the wax strap tower 6. The wax trap in this wax trap tower 6 is similar to the conventional system, and the wax vapor in the circulating gas is removed by condensation and adhesion to the trap element 8 (trap plate 8A, trap piece 8B). It turns out.

The exhaust gas that has passed through the wax trap tower 6 still contains a considerable amount of wax vapor, and the newly added dewaxing device 7 on the downstream side removes the wax vapor almost completely from the circulating gas. become. That is, the gas introduced into the dewaxing tank 10 is
1, all the remaining wax vapor adheres to the drum surface 11s and is removed. This is because the cooling drum 11 is constantly forcedly cooled and the cooling efficiency of the circulating gas is good, and the wax adhering to the drum surface 11s is continuously cut off by the cutter 12 attached to the gas outlet 10b side. This is because the surface 11s is brought into contact with the gas containing wax vapor in a fresh surface state with no attached wax. Therefore, the exhaust gas that has passed through the dewaxing tank 10 no longer contains almost any wax vapor, and therefore the downstream exhaust system path 5c and the vacuum pump 4 which are not kept warm.
The progress of the phenomenon of wax adhesion will be greatly eased compared to before. On the other hand, when focusing on the wax trapped in the dewaxing tank 10, the gas inlet 1 is placed in the cooling drum 11.
The solid wax adhering to the 0a side is continuously removed from the surface 11s by a cutter 12 attached to the cooling drum 11 on the opposite side, and is collected as solid wax W in the lower deposition tank 10B. In other words, the wax adhering to the cooling drum 11 is automatically removed each time the drum 11 rotates, and there is no need for troublesome work such as heating and melting in the wax strap tower 6. . In other words, maintenance-free working conditions are established for removing the wax, and no extra energy is consumed in remelting the wax. This also greatly simplifies maintenance and management, in addition to significantly reducing the conventional inspection and repair work that required frequent inspection and cleaning of piping on the exhaust system path 5c side. It will bring about change. The solid wax w deposited in the dewax tank 10 may be taken out and collected by opening the door 10c at an appropriate time.

Although one embodiment has been described above, the embodiment of the present invention is not necessarily limited to the embodiment described above. In particular, in the above embodiment, the dewaxing device 7 according to the present invention is added to the existing dewaxing device (wax strap tower 6) and used, but the dewaxing device according to the present invention is used. Of course, only 7 may be used. FIG. 3 shows an example of the configuration in such a case, in which a necessary number of dewaxing devices 7 having the internal configuration described above are interposed in series in the exhaust system 5 of the sintering furnace 1. ing. By arranging only the novel dewaxing device 7 in an appropriate number of stages in the exhaust system 5, the inherent advantages of the above-described dewaxing device 7 will be doubled.

[Effects of the invention] As mentioned above, if the dewaxing device of the present invention is used by interposing it in the exhaust system of a sintering furnace, it is possible to guarantee much higher dewaxing performance than before, so that the The problem of wax solidifying inside the vacuum pump in the piping of the exhaust system due to wax vapor can be greatly alleviated, and stable operation of the device can be ensured over a long period of time. Also,
In addition to this, since the dewaxing device itself can be used without maintenance, there is also the advantage that the maintenance and management of the entire exhaust system is significantly simplified.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an exhaust system for a sintering furnace showing an embodiment of the present invention, and FIG. 2 is a perspective view showing a specific example of the structure of a cooling drum incorporated in the dewaxing device. FIG. 3 is a schematic cross-sectional view of an exhaust system for a sintering furnace showing another embodiment of the present invention. 1...Sintering furnace (chamber), 2...Tight box, 2a...Exhaust pipe, a...Processed product (powder molded product), 3...Heater, 4...Vacuum pump, 5,
5a, 5b, 5c... Exhaust system line, 6... Wax trap tower, 6A... Conduit, 7... Dewaxing device, 8... Trap element, 10... Dewaxing tank, 10a... Gas inlet, 10b... ...Gas outlet, 10A...Upper space, 10B...Lower space, 11...Cooling drum, 11A...Cooling drum body, 11B...Cooling drum lid, 11C...Cooling drum shaft, 11s... drum surface, 12
...Katsuta, 13...Traction spring, 14,15...
Sprocket, 16... Chain, 17... Inflow pipe, 18... Inflow hole, 19... Outflow hole, 20...
outflow pipe.

Claims (1)

[Scope of utility model registration request] A dewaxing device characterized in that a cooling drum is rotatably disposed in a dewaxing tank through which gas containing wax vapor flows, and a cutter for cutting the drum surface is attached to the surface of the cooling drum.