FR2606790A1 - PROCESS FOR THERMALLY PROCESSING SMALL METAL PARTS AND INSTALLATION FOR ITS IMPLEMENTATION - Google Patents

Abstract

THE INVENTION RELATES TO THE HEAT TREATMENT OF SMALL METAL PARTS. THE PROCESS ACCORDING TO THE INVENTION, IN WHICH THE PARTS ARE TREATED IN A PROTECTIVE ATMOSPHERE 1 THEN IMMERSED IN AN OIL BATH 5 WHERE THEY ARE SOAKED, IS ESSENTIALLY CHARACTERIZED IN THAT THE POLLUTED ATMOSPHERE IS SUCKED ABOVE 13 FROM THE BATH, SEPARATE THE OIL 11 AND RETURN TO THE BATH, AND RETURN THE CLEANED ATMOSPHERE INTO THE HEAT-TREATMENT ENCLOSURE 1. APPLICATION TO CEMENTATION AND TEMPERING OF SMALL METAL PARTS.

Description

The present invention relates to a method of treating

  Thermal treatment of small parts or small items, in which the latter are treated in a protective gas atmosphere, then are immersed in an oil bath where they are quenched and quenched. The invention also covers an installation for the implementation

of the above process.

  Small heat treatment furnaces

  metal parts are known. It produces a cemen-

  these parts in a protected gas atmosphere.

  inert or inert. The parts are then processed in a subsequent oil quench chamber, containing a

  oil bath in which the cemented parts are plunged

  and soaked. For this purpose, the oven can

  continuously and have a quench tank in the open air or operate by successive charges and include a tempering chamber incorporated. In both cases, the treatment is done in a protective gas atmosphere. A disadvantage of the installations and processes

  known heat treatment of small metal parts-

  It is the fact that the oil vapors

  by the bath in the quench chamber diffuse into

  the heat treatment chamber. Where, in particular

  to bind, the hot parts are immersed in the oil, it releases large quantities of oil vapor. These vapors pollute the gaseous atmosphere of the treatment chamber and pollute moreover the parts to be treated, from

  deposition of oil droplets, which is detrimental to the outcome of operations.

  To treat the oil vapors and keep them away from the oven enclosure, the protective gas is

  until now repressed in large quantities

  bers, so that the gas stream maintains the vapors that emerge in the quench chamber away from the treatment chamber by allowing them to burn. Because the inert gas is also used

  as a flushing gas, a constant amount of

  larger than necessary for the heat treatment

  as such, resulting in high costs.

  Moreover, since the evaporated oil is burned, it is necessary to

  bring in bath new quantities.

  From these observations, the invention therefore aims at a method and an installation for eliminating

  oil vapors in a simple and economical way.

  According to the process according to the invention, the atmosphere of protective gas enriched with oil vapors is sucked above the oil bath, and this oil is then separated and returned to the bath and the oil. we also return the purified gas and rid of vapors

  of oil to the heat treatment chamber.

  This gives the advantage that the atmosphere

  of protective gas and oil follow

  the purified gas being returned to the processing chamber.

  thermal insulation and the separated oil is also

  seen in the oil bath. This creates a circulation of gas preventing the oil vapors

  get off the bath to get to the milking parlor

  because they are immediately sucked up. In addition, because the gas is recycled, only a small amount is consumed. Similarly, recycling

  oil decreases its consumption. We obtain a condition

  quick release of the protective gas.

  Aspiration is advantageously created before the insertion

  as the small parts are immersed in the oil bath, because it is especially when these hot parts are immersed in this bath that it emerges quantities

  considerable amounts of oil vapors which pollute the gas

  detector. According to another characteristic of the process, the composition is checked and corrected if necessary.

  of the recycled protective atmosphere. It is thus pos-

  sible to continuously and simply monitor the atmosphere in the heat treatment enclosure, without the need for special sampling lines

and replenishment.

  From an installation which comprises a heat treatment chamber under a protective gas atmosphere, followed by an oil quench chamber containing an oil bath, a door possibly being disposed between these chambers, an arrangement intended for the implementation of the method comprises, on the quenching chamber, a suction means of the gas polluted by the oil vapors released from the bath, a separator of

  the oil contained in this sucked gas, as well as

  return flow leaving said separator, firstly to the heat treatment chamber for the purified gas and secondly to the quenching chamber for the recovered oil. The suction means is advantageously a circulation pump which, according to another characteristic of the invention, is arranged in the

  led back to the heat treatment chamber.

  By means of this pump, it is technically easy to suck in the quenching chamber, the gas enriched with

  oil vapors. Having the circulating pump

  in the return duct to the treatment enclosure

  prevents it from being polluted by the oil.

  In an advantageous embodiment, the dis-

  positive separator comprises cooling coils traversed by a cooling fluid, the water by

  example, on which the aspirated atmosphere is passed.

  Such a coiled cooler is very easily achievable and otherwise works

very reliably.

  In the case where there is a door between

  heat treatment belt and the quenching chamber, its opening is coupled with the start of the suction means, which allows to take advantage of the advantage that, when the door is closed, the oil vapors can not diffuse the quenching chamber to the heat treatment chamber, so that there is no risk of pollution and so there is no need to vacuum to purify. Only when the door is open can oil vapors pass from the quench chamber to the treatment chamber. This risk is particularly great if the parts are immersed in the oil bath immediately after opening, releasing a large amount of heat because of their temperature.

  oil vapors which can then be very easily

  at the treatment chamber. However, because the startup of the suction means is coupled with the opening of the door, the oil vapors released

are sucked immediately.

  According to another characteristic of the invention, to facilitate aspiration and flow, a convergent cone is arranged in the suction zone of the

quenching chamber.

  Finally, according to yet another characteristic

  a device for controlling and correcting the composition of the protective atmosphere is mounted in the return duct towards the treatment enclosure or

  in this chamber. It allows to control and possibly

  to correct the composition of this atmosphere

  without the need for auxiliary connections. As -

  the suction circulates the gas continuously, it is possible to continuously perform this control or correction, so that the heat treatment of

  parts remains uniform over a long period.

  The invention will now be described in detail with reference to the accompanying drawing by way of non-limiting example, showing a schematic elevational view of an installation, comprising a heat treatment chamber and an oil quench chamber, intended for the heat treatment of small

metal parts.

  A heat treatment chamber 1 comprises (on the left in the figure) a door 2 through which the

  parts are introduced for treatment.

  This is carried out in a protective gas atmosphere, the treatment chamber comprising at the top a conduit 3 for the arrival of this gas. Arrows symbolize the meaning

  the flow of gas in the chamber 1.

  An oil quench chamber 4, containing an oil bath 5, follows, to the right of the figure, to the treatment chamber 1. A door 6 separates the chamber 1 from the chamber 4. The parts are removed from the room

  4 by another door 7. The cemen-

  In the bath, the bathers undergo a complementary treatment.

which consists of a quench.

  The quenching chamber 4 has in its upper part

  a device 8 for burning the oil.

  This room 4 has a private bathroom.

  suction and an oil separator, which are

  designed to suck the enriched and polluted gas atmosphere of oil vapors released by the bath 5 and to separate this oil. For this purpose, a circulation pump 9 draws through a conduit this polluted gas from the chamber 4 and drives it into a separator 11. This may comprise, for example, coils traversed by a cooling fluid such as water, on which passes the sucked gas and deposits the oil entrained. This deposited oil is returned to the bath 5 of the quenching chamber 4 by a return pipe 12. To improve the introduction of the atmosphere

  polluted which is above the bath 5, in the

  10, it is connected to the chamber 4 by

  through a convergent cone 13.

  The polluted atmosphere driven by suction being freed from oil vapors in the separator

  11 and thus purified, it is brought back to the

  1 by a conduit 14, in which is

also arranged the pump 9.

  The operation of the pump 9 can be coupled with the operation of the door 6 located between the treatment chamber 1 and the quenching chamber 4; that is to say that said pump 9 is turned on when this door 6 is opened to pass a load of cemented parts of this treatment chamber 1 to this

quenching chamber 4.

  Furthermore, a device for controlling and correcting the composition of the purified gas can be mounted in the return duct 14, between the separator 11 and

  treatment enclosure 1. This control and correction

  may be carried out by the regulating equipment

oven.

  The described arrangement creates for the protective atmosphere

  a circuit formed by the heat treatment chamber 1

  the oil quench chamber 4, the pipe 10, the separator 11, the return pipe 14 and the pump 9, which prevents the oil vapors that emerge from the bath 5 from reaching said enclosure. treatment, to pollute the atmosphere and to contaminate the parts in it. These vapors are eliminated immediately

thanks to the suction circuit.

  It goes without saying that it is possible to bring diversity

  its modifications to the process and the installation of

  thermal insulation of small metal parts,

  described and described without departing from the realm of

tion.

Claims (11)

  1. Process for the heat treatment of small parts, in which these parts are thermally treated in a protective gas atmosphere, then immersed in an oil bath where they are quenched, characterized in that the atmosphere is sucked up. polluted with oil vapors above the bath; this oil is separated and returned to the bath; and we send back the purified atmosphere, rid of   oil vapors, in the heat treatment chamber.   2. Method according to claim 1, characterized in that the suction current is created just before   to immerse the pieces in the oil bath.   3. Method according to one of claims 1 or   2, characterized in that the case is checked and corrected   the composition of the purified recycled atmosphere.   4. Process according to any one of the claims   1 to 3, characterized in that the   control and possible correction in combination with oven regulation.   5. Installation for the implementation of the process   according to any one of claims 1 to 4, comprising   an enclosure (1) for heat treatment in atmospheric   protector gas, followed by an oil quench chamber (4) containing an oil bath (5), a door (6) arranged between said enclosure (1) and said chamber (4), installation characterized in that it comprises: on the quenching chamber (4) a suction means (9) of the gaseous atmosphere polluted by the oil vapors released by the bath (5); a separator (11) of the oil contained in this polluted atmosphere, and return lines (12, 14) from said separator (11), on the one hand to the heat treatment chamber (1), for the refined atmosphere, and secondly   to the quenching chamber (4) for recovered oil.   6. Installation according to claim 5, characterized   in that the suction means is a circulation pump (9).   7. Installation according to claim 6, characterized   characterized in that the pump (9) is mounted in the conduit   (14) back to the heat treatment chamber (1).   8. Installation according to any one of the   5 to 7, characterized in that the separator (11) comprises a cooling coil traversed by a cooling fluid, such as water, and   over which the polluted gas sucked.   9. Installation according to any one of the   5 to 8, characterized in that, in the case where there is a door (6) between the heat treatment chamber (1) and the quenching chamber (4), its opening is coupled with the commissioning of the suction means (9).   10. Installation according to any one of the   5 to 9, characterized in that the quenching chamber (4) has a convergent cone (13) in the suction zone.   11. Installation according to any one of the   5 to 10, characterized in that a device   control and correction of the composition of the atmos-   purified protective phere is mounted in the conduit of   return (14) to the heat treatment enclosure (1) nomic.