SU1084112A1 - Apparatus for regulating gas exchange in mould - Google Patents

Abstract

1. A DEVICE FOR REGULATING A GAS EXCHANGE IN A CASTING FORM, comprising a housing and a diffuser attached to it, forming a cavity for placing the agent under pressure or creating a vacuum in it, attached to the end of the diffuser with a replaceable piece with cells filled with fusible material, and a chamber for melting coolant, hydraulically connected channels with the working cavity of the mold, characterized in that, in order to increase its efficiency, the removable cap is made in the form of two parallel and fastened around the periphery of the fins, fixed with holes in them. tubes forming the cells for the low-melting material, and the chamber for the melt-heat carrier is formed by facing surfaces of the end portions of the grid, the inner surface of the shell and the outer surfaces of the tubes. 2. Device - software item 1, characterized in that the tube grids are made constant along the length of the section. L 3. The device according to claim 1, characterized in that the tubes of the BbinOviHeHbi gratings are in the form of truncated cones. 00 GcE

Description

11: ;; k) reg ..-;:; -; refers to the foundry industry), namely, devices for controlling casting processes occurring in a gas-permeable form, and can be used mainly in the manufacture of responsible openwork and thin-walled parts of complex shape.

A device for regulating gas exchange in a mold, made in the form of an ampoule of a material, the melting point of which is chosen in the range of 60-400 ° C, is known.

Ampoules of material with the specified properties, containing agents enclosed in them for a given physicochemical interaction with the casting or metal poured, are placed in the required amount in the mold material when it is made at a distance from the casting surface, sufficient for thermal destruction of the shell material. During the period of pouring and hardening of the metal under the influence of heat transferred by the poured metal, the shell of the ampoule is destroyed and the gases outflow or suction from the surface with the evacuation of these gases into the volume of the ampoule in which the predetermined vacuum was created or the getter absorbing the gas was placed. When implementing the device, an improvement is achieved in the control of the gaseous medium in the casting mold, thereby improving the quality of castings or ingots.

However, this ampoule cannot be reused because of its unsuitability after the first use as a result of thermal destruction of the shell.

A device for regulating the gas volume in a casting mold, made in the form of a body made of a material more refractory than the metal being poured and provided with a removable metal cap attached to this body with a melting point of 50-350 ° C and an element of heat-conducting material that interacts with a replaceable lid, is known. 2

Agents of the required chemical composition under pressure, getters, or vacuum can be enclosed in the volume of the ampoule.

When forming, the required number of ampoules is placed in the mold material at a distance from the mold border with a casting sufficient to thermally destroy the ampoule cap under the influence of the transferred melt or heat cast through the heat-conducting elements. The number of ampoules filled with the necessary agents and their location is chosen depending on the material, size and configuration of the casting or ingots.

When pouring molten metal into its intended volume

the heat of the melt is transferred both through the mold material and through the heat-conducting elements of the replaceable lid of the ampoule. Under thermal action, the ampoule cover is heated in the contact zone with the heat-conducting element to its melting point, at which its local destruction takes place, and the agent enclosed in the ampoule gets access to the mold and interacts with the atmosphere of the mold at the surface of the melt or at the surface of the casting. If there is a vacuum in the ampoule, gases are sucked from the surface. The body of the ampoule can be reused in the manufacture of subsequent castings.

However, in the process of compaction of the molding material with a device for regulating gas exchange placed in it, a displacement or even a departure of the heat-conducting element from the ampoule cap may occur. Such waste and displacement of the heat-conducting element are accompanied by the penetration of the molding material into the zone of mechanical contact of the above-mentioned parts with a violation of the thermal contact of the melt necessary to pour into the mold to control the processes occurring in it and, consequently, decrease the reliability of the device.

It is also known a device comprising a housing provided with a cavity for placing an agent under pressure or creating a vacuum, a lid secured to the housing, and an element of heat-conducting material. The element is made in the form of a diffuser attached to the lid, the narrow part of which is equipped with a stopper made of low-melting material and facing the inside of the body cavity, and the gusher is equipped with a mesh fixed in it to protect the internal cavity of the diffuser from falling into the molding material 3.

During operation of this device, heat from the molten metal or hot casting that is in the form is transferred through the material and diffuser to the low-melting plug, which melts, in turn, opens the access of the active agent to the form containing the melt or hot casting. On the path of the agent to the form of a conically expanding channel of the diffuser, as the living cross section of the latter increases, the flow rate of the agent decreases and its pressure increases, i.e. The velocity head is organized and directed into the energy of its pressure, necessary for a uniform effect on the outlet of the diffuser on the material of the form, penetrating through its pores under pressure to the atmosphere of the form for a given interaction with it.

When using the device as a suction and when the atmosphere in the case is withdrawn from the surface of the melt or the surface of a casting into a vial ampoule, the diffuser also functions as organizing a flow wide for the intake of gases and a channel narrowing in the vial into the ampoule. The diffuser works as a confuser. The removal of the corrosive atmosphere from the surface of the mold, as in the first case, begins after the melting of the plug of low-melting material. The presence of reliable thermal contact between the sealed heat-conducting diffuser and the low-melting plug ensures reliable and trouble-free operation of the device.

However, the volume of the device is not fully utilized. Thus, the volume of the cavity of the diffuser, in its original state, remains unused to accommodate an agent or vacuum in it.

The closest to the proposed technical essence and the achieved result is a device comprising a housing with a cavity for placing an agent under pressure or creating a vacuum in it and a diffuser attached to it carrying a mesh fixed in it, a replaceable cell cover made of heat-conducting material the openings of which are hermetically sealed with a stopper of a low-melting material, as well as a chamber for melting the heat transfer fluid, which is hydraulically connected to the working cavity of the mold with tubes (channels) 4.

When the metal is cast by the casting mold, the natural level of the melt rises naturally and the chamber is filled with melt. The heat flux is transferred from the melt-heat carrier to the low-melting material of the plug through the walls of this chamber and the safety net to melt the plug material and start the operation of the device. Further action of the device is similar to the action of the devices described above.

Using the volume of the diffuser as an additional container for enclosing the desired agent or vacuum and forming a chamber for the melt-heat carrier, which is special to the low-melting plug through the channel from the working volume of the mold, increases the efficiency of the device.

However, the effectiveness of the known device is not high enough and is due to the duration of melting of the plug material in connection with the separation of the annular chamber for the melt-heat carrier from the central part of the grid, which carries in the cells a low-melting material of the plug. When the coolant is already filled with the annular chamber, the plug material is initially melted, enclosed in the cells of the peripheral part of the grid adjacent to the annular chamber, and finally in the central part.

The purpose of the invention is to increase the efficiency of the device.

This goal is achieved by the fact that in a device for regulating gas exchange in a mold containing a housing and a diffuser attached to it, forming a cavity for placing the agent under pressure or creating a vacuum in it, fixed to the end of the diffuser a replaceable cap with cells filled with a low-melting material and melt heat transfer chamber, hydraulically

The interchangeable lid connected with channels with the working cavity of the mold is made in the form of two lattices arranged parallelly and bonded around the periphery with shells with tubes fixed in their holes forming cells for a fusible material, and the chamber for the melt-heat carrier is formed by facing end surfaces lattice parts, the inner surface of the shell and the outer surfaces of the tubes.

In this case, the tubes of the gratings can be made constant along the length of the section, or in the form of truncated cones.

FIG. 1 schematically presents the proposed device, a longitudinal section; in fig. 2 is a view A of FIG. one.

The arrows in the drawing denote the entrance of the molten metal into the chamber when it fills the mold and the exit of air and / or gases from this chamber as it is filled with the melt-heat carrier (upper arrow).

The device comprises a housing 1 with a cavity 2 therein for accommodating the agent under pressure or creating a vacuum therein and a diffuser 3 with a cavity 4 therein, attached to the housing and carrying a chamber 5 for melting metal (not shown) fixed therein, performing in this chamber role of coolant.

The melt-heat transfer chamber 5 is a lattice 6 connected by a shell 7 and tubes 8 fixed in the lattices by flaring and / or welding. The shell 7 with gratings b is connected by welding and is made with a screw thread 9 for connection with the diffuser 3 and the possibility of subsequent replacement of the chamber 5 for the melt-coolant. The diffuser 3 for this is also provided with a screw thread. In order to achieve density, the joint junction can be lost or compacted by one of the known methods, for example using an annealed red copper ring (not shown). The tubes 8 (in longitudinal section) can be made both constant along the section and variable - in the form of truncated conical shells. Tubes 8, having the form of conical shells, can be installed in the grids 6 with a large base of the cone both towards the mold and towards the cavity 4 of the diffuser 3. In the initial state of the device, the holes in the tubes 8, as well as cells in the grid of the prototype device , filled with low-melting material 10 of the plug 11, for example, tin nystosyvtsymi, by pouring the material. The direction of installation of the tubes 8, made in the form of conical shells, a large base of the cone in one direction or another is determined by the conditions for increasing the reliability of fixing the low-melting material 10 of the plug 11 when the loads are applied to this material in the initial state of the device. As such loads, the pressure of the agent placed in cavities 2 and 4 of device 1 and diffuser 3, as well as the effect of atmospheric pressure when there is a vacuum in the cavity 2 of device 1 and the pressure of material 2 of the mold 13 under vacuum, is taken into account. in the cavity 2. For the case of pressure of the agent placed in the cavity 2 of the device 1, it is better to install the tubes 8 with a large base towards the cavity 2. For the case of a vacuum in the cavity 2 of the device I of the tube 8 it is better to install with a large base towards of the material 12 of the casting mold 13. Thus, the installation of tubes 8 made in the form of truncated conical shells with a large base towards greater pressure increases the reliability of fixing the low-melting material 10 of the plug 11 in the pipes. The installation of tubes 8, made in the form of truncated conical shells, with a large base towards the material 12 of the mold 13 when the agent is supplied under pressure while regulating gas exchange improves the conditions for the agent to be supplied to the metal melt, because when the pressure head in the tubes 8 in this case, the function of diffusers is transformed into pressure energy, providing better conditions for. penetration of the agent through the material of the mold. The tubes 8 installed in this position also provide the best conditions for the removal of gas from the mold 13 when the vacuum is contained in the housing 1, since the holes are directed with large bases towards the extraction of gases. The annular space of chamber 5 is designed to be filled with melt-coolant. For this purpose, tubes 15 and 16 are fixed in the outer tube sheet 14, the free ends of which go out into the volume of the mold 13. In this case, the bottom of the tubes 15 is designed to introduce the molten metal into the annular volume of the chamber 5, the top 16 to drain air or gases from of this volume when the melt is introduced into the chamber and its level is raised in it. Thus, the implementation of the melt-heat transfer chamber 5 in the grid is understood to mean the implementation of the chamber with walls with gratings in the holes of which tubes are fixed, the inner surfaces of which, in combination with the outer surfaces of the grids in which they are fixed, function as cells the known mesh (as in the prototype), and the outer surfaces of the tubes, together with the inner surfaces of the grids in which the tubes are fixed, perform the functions of the chamber for the melt-coolant. The proposed embodiment of the melt chamber 5 increases the efficiency of the device by accelerating the melting of the material with a fusible plug, since the melt-coolant introduced into the annular space of chamber 5 is fed into each tube 8 (cell) filled with the low-melting material 10 of the plug P. During operation, this is similar supplying the melt-heat carrier along hollow mesh threads to the cells filled with solidified fusible material 10 of the plug 11, i.e. the annular space in chamber 5 performs the functions of channels that could be discharged. in each thread of the grid to increase the efficiency of the device. Installing the tubes 8 between the grids 6 is guviped when using the device, the stability of the shape and the strength of the chamber 5 for melt heat carrier working in a diffuser under pressure instead of the mesh B is the device of the prototype. In the initial state, the cavity 2 of the device housing 1 and the cavity 4 in the diffuser 3 are hydraulically connected, and the cavity of the melt-heat transfer chamber 5 is hydraulically connected to the volume of the mold 13 by tubes 15 and 16. The device in the material 12 of the mold 13 is stirred at the rate of the most efficient the use of agents introduced in the regulation, or vacuum. The number of devices is chosen depending on the type and grade of material, the size and configuration of the castings, as well as the responsibility of the casting or ingot. The peculiarity of the proposed device is the melting of low-melting material 10 of the plug 11 under the thermal effects of the melt-heat carrier directly on the walls of the tubes 8 (cells) while filling the annular chamber space with this melt. To reuse the device intended for regulating gas exchange in a mold, it is enough to replace in it the already used chamber 5 with the melt-coolant frozen in it. This embodiment of the melt chamber 5 also increases the reliability of the device, as it reduces the mechanical deformations of the cellular device (chamber 5 for the molten heat carrier used instead of the mesh mounted in the surrounding it in its chamber) when the control devices are mixed in the material 12 of the mold 13 and then molded .

The proposed improvement of the listed properties of the device designed to regulate the gas exchange in the casting mold, as well as its simplicity, reliability, and using only the heat energy of the molten metal to be used to activate the device will allow it to be widely used in the national economy and to receive savings due to the improvement of physical mechanical properties of the material castings or ingots.

FIG. 2

Claims (3)

1. DEVICE FOR REGULATING GAS EXCHANGE IN A CASTING FORM, containing a body and a diffuser fastened with it, forming a cavity for placing the agent under pressure or creating a vacuum in it, an exchangeable core fixed on the end of the diffuser with cells filled with easily fusible material, and a chamber for melt -heater, hydraulically connected by channels with a working cavity of the mold, characterized in that, in order to increase its efficiency, the replaceable cover is made in the form of two parallel and fastened about the periphery of the shell arrays with fixed openings at their · tubes forming the cell for the low-melting material and the heating medium chamber-melt is formed by the facing surfaces of end portions of the lattice, the internal surface of the sleeve and the outer surfaces of the tubes. 2. The device according to π. 1, characterized in that the tube lattices are made constant along the length of the section. 3. The device according to π. 1, characterized in that the tube grilles are made in the form of truncated cones.