Isothermal quenching pool for nodular cast iron

Abstract

The invention discloses a spheroidal graphite cast iron isothermal quenching pool, and relates to the technical field of isothermal quenching, the spheroidal graphite cast iron isothermal quenching pool comprises a pool body, a salt bath solution is contained in the pool body, a plurality of heat exchange pipes are arranged between two opposite directions in the pool body, the heat exchange pipes are distributed on the surface of a workpiece, and a heat exchange medium circularly circulates in the heat exchange pipes and exchanges heat with the solution in the pool. A plurality of independent magnetic bodies are arranged on the heat exchange pipe in the length direction of the heat exchange pipe, abutting pieces capable of being heated to deform are further arranged on the heat exchange pipe at intervals, when a workpiece enters the pool body, the magnetic bodies are attracted by attractive force and change the orientation of the abutting pieces, and heat radiation of heat exchange of the workpiece enables the abutting pieces to extend and unfold towards the workpiece in the length direction. According to the spheroidal graphite cast iron isothermal quenching pool, the heat exchange pipes are arranged to be in a movable form and can be adaptively adjusted according to the shape of the surface of a workpiece, so that all the heat exchange pipes are located on the same isothermal surface, the stability of the temperature of a solution in the edge area of the workpiece is better ensured, and the quenching effect is better.

Description

Technical Field

[0001] The invention relates to the technical field of isothermal quenching, in particular to a ductile iron isothermal quenching pool. Background Art

[0002] Isothermal quenching refers to the quenching method in which the workpiece is kept at the temperature of the lower bainite transformation zone for a long time after quenching and heating, so that the isothermal transformation of austenite is completed and the lower bainite structure is obtained. The typical process of isothermal quenching of ductile iron is as follows: first, the ductile iron original is heated to the austenitizing temperature (840-950℃), kept warm for 1-2 hours, so that it is completely transformed into carbon-rich austenite, and then it is quickly quenched into a salt bath at the isothermal transformation temperature of austenite (250-400℃), kept warm at this temperature for 1-2 hours, and then taken out of the furnace and air-cooled to room temperature.

[0003] When the cast iron workpiece is quenched in the quenching pool, because its temperature is much higher than the temperature in the pool, it will exchange heat with the medium in the pool (salt bath solution). Therefore, the salt bath solution in the pool forms a stepped isothermal surface on the surface of the workpiece according to the distance. The heat exchange system of the salt bath solution generally circulates the heat exchange medium through a pipeline to maintain the temperature stability of the salt bath solution. This method can keep the temperature in the pool within a relatively stable range, but there is still a large temperature difference locally, especially after the workpiece enters the pool. The surface of the workpiece has various shapes, so the distance between the heat exchange system and the workpiece surface is different, which makes a certain heat exchange temperature difference at various places on the workpiece surface, which is not conducive to the overall balanced quenching of the workpiece. Different temperatures cause different strength differences in different areas of the workpiece surface. To this end, we propose a ductile iron isothermal quenching pool. Summary of the invention

[0004] The object of the present invention is to provide a ductile iron austempering pool to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a ductile iron isothermal quenching pool, comprising a pool body, a salt bath solution is contained in the pool body, a workpiece is placed in the middle area of ​​the pool body through a hanger, a plurality of heat exchange tubes are arranged between two opposite directions in the pool body, the heat exchange tubes are distributed on the surface of the workpiece, the heat exchange tubes are metal hoses, and a heat exchange medium circulates in the heat exchange tubes to exchange heat with the solution in the pool, a plurality of independent magnetic bodies are arranged on the heat exchange tubes along their length direction, and heat-deformable resistance pieces are also arranged at intervals on the heat exchange tubes, when the workpiece enters the pool body, the magnetic body is attracted by gravity and changes the direction of the resistance piece, and the heat radiation of the heat exchange of the workpiece causes the resistance piece to extend and unfold toward the workpiece along the length direction.

[0006] Preferably, the heat exchange tube is a metal bellows.

[0007] Preferably, the outer wall of the heat exchange tube is provided with a plurality of ring sheets at intervals along the axial direction thereof, and the magnetic body is fixed on the ring sheets and is located in an area where the ring sheets are close to the workpiece.

[0008] Preferably, the abutment is disposed on the ring sheet and is located at the same position as the magnetic body, and when the magnetic body is in an attracted state, the extending direction of the abutment is consistent with the direction of attraction.

[0009] Preferably, the main body of the ring sheet is made of a material with a lower density than the salt bath solution in the tank body, and the overall average density of the heat exchange medium contained in the heat exchange tube and the part of the heat exchange tube in the tank body is equal to the density of the salt bath solution in the tank body.

[0010] Preferably, the ring sheet and the heat exchange tube can rotate relative to each other, and the relative rotation angle is β, and β is less than 90°.

[0011] Preferably, the abutment member is in a spiral shape with a gradually decreasing diameter from the ring sheet end to the workpiece end.

[0012] Preferably, the spiral of the abutment is a rectangular spiral, which is initially fixed to the outer peripheral side wall of the ring sheet, and when the magnetic body is in an attracted state, the extending direction of the abutment is consistent with the direction of attraction.

[0013] Preferably, the cross section of the ring piece is waist-shaped

[0014] Preferably, the ends of the heat exchange tubes can be telescopically arranged between the tank wall.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention arranges the heat exchange tubes in a movable form and makes adaptive adjustments according to the shape of the workpiece surface, so that each heat exchange tube is on the same isothermal surface, thereby better ensuring the stability of the solution temperature in the edge area of ​​the workpiece and achieving a better quenching effect;

[0017] The ring sheet in the present invention can not only avoid excessive bending of the heat exchange tube, but also achieve the same effect as gravity through the inclination of its end surface, and play a supplementary role when the initial temperature of the workpiece is high and the magnetism is weak. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a virtual isothermal surface of the entire surface of a workpiece of the present invention;

[0019] Figure 2 for Figure 1 Schematic diagram of the AA section structure;

[0020] Figure 3 It is a schematic diagram of the structure of the heat exchange tube;

[0021] Figure 4 for Figure 2 Schematic diagram of the structure between the heat exchange tube and the workpiece in the middle BB section state;

[0022] Figure 5 Schematic diagram of different installation methods of the magnetic body on the ring sheet;

[0023] Figure 6 is a schematic diagram of the initial state of the magnetic body;

[0024] Figure 7 It is a schematic diagram of the rotation angle of the magnetic body relative to the initial state of the heat exchange tube after rotation.

[0025] In the figure: 1- pool body; 2- heat exchange tube; 3- magnetic body; 4- resistance member; 5- ring plate. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] See also Figure 1 , Figure 2 and Figure 4 The present invention provides a technical solution: a ductile iron isothermal quenching pool, comprising a pool body 1, in which a salt bath solution is contained, and the heated ductile iron workpiece is transferred to the pool body 1 through a hanger for isothermal quenching. In order to keep the temperature of the solution in the pool body 1 stable, a heat exchange system is arranged in the pool, generally through a heat exchange tube 2, a heat exchange medium circulates in the heat exchange tube 2, so as to keep the temperature stable. In the prior art, the heat exchange tube 2 is a fixed tube, that is, the position is fixed, and the surface of the workpiece generally has various shapes, which will cause the distances between each section of the heat exchange tube 2 and the surface of the workpiece to be different. After the workpiece enters the pool, because the temperature is much higher than that of the solution, it will quickly exchange heat, and at the same time, the solution rises steadily and exchanges heat with the heat exchange medium. Because the distances between the heat exchange tube 2 and the surface of the workpiece are different, the influence of each section of the heat exchange tube 2 on the heat exchange of the workpiece surface is different. Therefore, in this solution, the heat exchange tube 2 adopts a movable metal hose to facilitate the adaptive adjustment of the distance according to the surface of the workpiece, as follows;

[0028] See also Figure 1After the workpiece is placed in the pool, the salt bath solution forms an isothermal surface covering the workpiece at an equal distance on its surface. Because of the shape of the workpiece surface, the isothermal surface is also the same as the workpiece surface. Therefore, as long as the heat exchange tube 2 is on the same isothermal surface, the temperature around the workpiece can be stabilized. Because the surfaces of workpieces to be quenched are different, the heat exchange tube 2 in the form of a metal hose can change the distance from the workpiece surface according to the workpiece;

[0029] like Figure 2 and Figure 4 As shown, in order to control the position of the heat exchange tube 2, a magnetic body 3 is installed on the heat exchange tube 2. When the temperature of ductile iron drops to the Curie point (about 770°C), the magnetic body 3 on the heat exchange tube 2 will begin to recover its magnetism. At this time, the magnetic body 3 on the heat exchange tube 2 will move closer to the workpiece under the action of gravity. In order to make each section of the heat exchange tube 2 on the same isothermal surface ( Figure 2 is the isotherm of the cross section), a resistance piece 4 is arranged at intervals on the heat exchange tube 2, and the resistance piece 4 is divided into two parts, the outer surface is a high temperature resistant heat insulating flexible material, and the inner part is a memory metal skeleton. When the workpiece enters the pool for quenching and heat exchange, the resistance piece 4 will also be affected by the temperature and begin to deform and expand, and one end contacts the surface of the workpiece, thereby generating a fixed distance, and the heat exchange tube 2 is balanced by the gravity and the reaction force generated by the resistance piece 4, so that each section of the heat exchange tube 2 is maintained at the same or close distance from the corresponding surface of the workpiece;

[0030] like Figure 2 As shown, the different heat exchange tubes 2 are initially approximately parallel and form an annular cylindrical space, so their two ends are respectively fixed to the corresponding two sides of the inner wall of the pool body 1 (which can be the corners). When the workpiece is placed, the heat exchange tube 2 on the upper side of the above-mentioned columnar space needs to be pushed away, and then pushed back after the workpiece is placed. Then, when the gravity is generated, it reaches the isothermal surface. The magnetic body 3 is only located in a partial area on one side of the radial direction of the heat exchange tube 2, rather than the entire circumferential side, so that the gravity can adjust the direction of the pipeline, that is, adjust the extension direction of the resistance member 4 to avoid the direction error of the resistance member 4, because in the initial state of the workpiece being placed, the sinking of the workpiece causes the heat exchange tube 2 to be pushed in the direction away from the workpiece, and the heat exchange tube 2 will also locally twist itself, so the direction is corrected by the magnetic body 3.

[0031] Different workpieces have different volumes, so the required lengths of the heat exchange tube 2 are different. Therefore, a telescopic mechanism is set between the end of the heat exchange tube 2 and the inner wall of the pool body 1 to control the length of the heat exchange tube 2 in the pool to prevent the heat exchange tube 2 from being too long and fitting to the surface of the workpiece under the action of gravity, thereby destroying the stable state on the same isothermal surface.

[0032] As one of the embodiments, the heat exchange tube 2 is a metal bellows. Due to the corrugated structure, the metal bellows has a minimum bending diameter when bent and cannot fold, thereby avoiding excessive bending of the heat exchange tube 2 due to local protrusion or depression of a certain part of the workpiece, which affects the change of the fluid cross-sectional flow rate of the heat exchange medium, thereby affecting the isothermal state.

[0033] As another embodiment, a plurality of ring sheets 5 are evenly spaced along the axial direction on the surface of the heat exchange tube 2 to produce the same effect of the corrugated structure. When the heat exchange tube 2 is bent and reaches the maximum bending degree, the edges of adjacent ring sheets 5 will touch each other, thereby generating interference and preventing further bending. The magnetic body 3 is fixed on the ring sheet 5 and is located in the area where the ring sheet 5 is close to the workpiece. The orientation of the magnetic body 3 on different heat exchange tubes 2 is different, such as Figure 2 As shown, the magnetic body 3 on the heat exchange tube 2 located above the workpiece is fixed in the area below the axis of the ring sheet 5, while the magnetic body 3 located below the workpiece is fixed in the area below the axis of the ring sheet 5, and the magnetic body 3 on the heat exchange tube 2 located above ...

[0034] like Figure 4 As shown, one of the functions of the magnetic body 3 is to change the direction of the resistance member 4. Therefore, only when the magnetic body 3 is attracted by gravity, the resistance member 4 is located in the area between the magnetic body 3 and the workpiece and the extension direction of the resistance member 4 is the gravity direction, can the resistance member 4 be extended to contact the corresponding position of the workpiece. If the resistance member 4 deviates, it may be tilted under the action of gravity, and finally the heat exchange tube 2 is attached to the workpiece.

[0035] When the heat exchange tube 2 is a metal hose, its density is greater than the density of the solution in the pool, so the heat exchange tube 2 as a whole will sink, which also leads to the fact that under the action of gravity, Figure 2 In this state, the forces on the heat exchange tubes 2 in different areas are different. The direction of gravity is the same but the direction of attraction is different. If the attraction is small, it is not enough to make the heat exchange tubes 2 reach the isothermal surface. Therefore, the density of the ring sheet 5 is used to make the overall density of the ring sheet 5 and the heat exchange tube 2 equal to the density of the solution in the pool. Here, equal means close, because the solution in the pool will evaporate and be consumed. Although there is a replenishment mechanism, the overall density is also in a dynamic equilibrium state. Therefore, it is only necessary to make the density close to minimize the influence of gravity.

[0036] like Figure 3 , Figure 6 and Figure 7As shown, the ring sheet 5 can be arranged on the heat exchange tube 2 in a rotatable manner relative to the surface of the heat exchange tube 2. For example, an annular groove is provided and a limit is provided in the annular groove to enable the heat exchange tube 2 to rotate within a range. Theoretically, the relative rotation angle β can be rotated and reset under the action of gravity as long as the magnetic body 3 is not rotated to the position of the farthest point on the side of the heat exchange tube 2 away from the workpiece. However, considering the friction of rotation and the torsion of the heat exchange tube 2 itself, the angle is preferably less than 90 degrees, and angles such as 60° and 45° can be used. The specific needs are selected according to different diameters of the heat exchange tube 2.

[0037] If the resistance member 4 is only in the form of a single rod, it is not easy to produce a stable supporting state. Therefore, the resistance member 4 is configured to have a structure similar to a coil spring to increase the contact range with the workpiece surface, thereby forming a stable support. The spiral resistance member 4 also stretches more evenly when heated.

[0038] like Figure 4 and Figure 5 As shown, the cross section of the ring piece 5 is waist-shaped, that is, trapezoidal, and the magnetic body 3 is installed in the side area of ​​the ring piece 5 where the cross section thickness is relatively thin. Because when the workpiece is quenched and heat exchanged, the high-temperature solution will flow to the low-temperature area, and then the solution flow will produce the same effect as gravity, which acts on the inclined surfaces of the two end faces of the ring piece 5, and the ring piece 5 will be forced to rotate;

[0039] Further, the resisting member 4 is fixed to the outer edge surface of the thinner region of the ring piece 5, so that when the ring piece 5 rotates under the action of gravity or the like, it drives the corresponding position direction to expand.

[0040] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0041] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A ductile iron isothermal quenching tank, comprising a tank body (1), characterized in that: A salt bath solution is contained in a pool body (1), and a workpiece is placed in the middle area of ​​the pool body (1) through a sling. A plurality of heat exchange tubes (2) are provided between two opposite directions in the pool body (1), and the heat exchange tubes (2) are distributed on the surface of the workpiece. The heat exchange tubes (2) are metal hoses, and a heat exchange medium circulates in the heat exchange tubes (2) to exchange heat with the solution in the pool. A plurality of independent magnetic bodies (3) are provided on the heat exchange tubes (2) along their length direction, and heat-deformable resistance pieces (4) are also provided at intervals on the heat exchange tubes (2). When the workpiece enters the pool body (1), the magnetic body (3) is attracted by gravity and changes the direction of the resistance piece (4), and the heat radiation of the workpiece during heat exchange causes the resistance piece (4) to extend and expand toward the workpiece along the length direction.

2. A ductile iron austempering tank according to claim 1, characterized in that: The heat exchange tube (2) is a metal bellows tube.

3. A ductile iron austempering tank according to claim 1, characterized in that: The outer wall of the heat exchange tube (2) is provided with a plurality of ring sheets (5) at intervals along the axial direction thereof, and the magnetic body (3) is fixed on the ring sheet (5) and is located in an area of ​​the ring sheet (5) close to the workpiece.

4. A ductile iron isothermal quenching tank according to claim 3, characterized in that: The resisting member (4) is arranged on the ring sheet (5) and is located at the same position as the magnetic body (3); and when the magnetic body (3) is in an attracted state, the extending direction of the resisting member (4) is consistent with the direction of attraction.

5. A ductile iron austempering tank according to claim 3, characterized in that: The main body of the ring sheet (5) is made of a material having a lower density than the salt bath solution in the tank body (1), and the overall average density of the heat exchange medium contained in the heat exchange tube (2) and the portion of the heat exchange tube (2) in the tank body (1) is equal to the density of the salt bath solution in the tank body (1).

6. A ductile iron austempering tank according to claim 3, characterized in that: The ring sheet (5) and the heat exchange tube (2) can rotate relative to each other, and the relative rotation angle is β, and β is less than 90°.

7. A ductile iron austempering tank according to claim 3 or 4, characterized in that: The abutment member (4) is in a spiral shape with a gradually increasing diameter from the ring sheet (5) end to the workpiece end.

8. A ductile iron austempering tank according to claim 7, characterized in that: The spiral of the resisting member (4) is a rectangular spiral, which is initially fixed to the outer peripheral side wall of the ring sheet (5), and when the magnetic body (3) is in an attracted state, the extending direction of the resisting member (4) is consistent with the direction of attraction.

9. A ductile iron austempering tank according to claim 3, characterized in that: The cross section of the ring piece (5) is waist-shaped.

10. A ductile iron austempering tank according to claim 1, characterized in that: The two ends of the heat exchange tube (2) and the wall of the pool body (1) are telescopically arranged.

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