KR102385162B1 - Casting method of vehicle axle box - Google Patents

Abstract

The present invention relates to a method for casting an axle box for a vehicle, comprising: a joining step of separating and preparing a mold formed with a pattern corresponding to the axle box into an upper mold and a lower mold, installing a core for forming a core in the lower mold, and then raising the upper mold for joining; a molten metal injection step of injecting molten metal obtained by melting cast iron into the mold; a casting acquisition step of acquiring a casting maintaining a molding pattern by removing the molten metal from the mold after the molten metal injected into the mold is cooled and solidified for a predetermined time when the injection of the molten metal corresponding to a volume of the mold is completed; and a quality inspection step of performing a quality inspection of the casting by performing a non-destructive test on the casting after heat treating the casting at a preset temperature. Therefore, the present invention has an effect of minimizing the occurrence of a defect in an axle box when casting the axle box provided to protect an axle, which is a device for supporting the weight of a vehicle and transmitting power to a wheel.

Description

Casting method of axle box for vehicle {CASTING METHOD OF VEHICLE AXLE BOX}

The present invention relates to a method of casting an axle box for a vehicle, and specifically, to minimize the occurrence of defects in the axle box during casting of the axle box provided to protect the axle, which is a device that supports the weight of a vehicle and transmits power to the wheels. It relates to a casting method of an axle box for a vehicle.

In general, an axle box (or journal box) is a device that supports the weight of a vehicle and transmits power to the wheels of the vehicle by being supported on a bogie frame by an elastic support member made of a rubber spring such as a coil spring, conical or chevron. am.

These axle boxes are usually applied to bogies such as high-speed trains moving along railroad tracks to support the vertical load of the bogie frame and to maintain the stability of vehicle driving. It has great relevance to increasing the driving stability of

On the other hand, in the conventional axle box, a finished product is generally produced through machining after casting using cast steel, but cast steel has limitations in that it has poor castability and lacks wear resistance and damping ability.

Accordingly, Korean Patent Registration No. 10-1735340 discloses a technology in which the axle box is made of forged aluminum alloy to reduce the weight of the axle box and increase the ease of manufacturing the axle box.

However, in the prior art described above, since the material of the axle box is used as an aluminum forging alloy, there is a problem that durability in a high temperature environment is lower than that of an axle box made of cast steel or cast iron.

Therefore, there is a need for a casting technology of an axle box for a vehicle that has high durability compared to an axle box made of cast steel or aluminum, and can improve castability of cast steel.

Accordingly, the present invention provides a casting method of an axle box for a vehicle that minimizes the occurrence of defects in the axle box when casting an axle box provided to protect an axle, which is a device that supports the weight of a vehicle and transmits power to the wheels. There is a purpose.

In order to achieve the above object, in the casting method of an axle box for a vehicle according to an embodiment of the present invention, a mold having a pattern corresponding to the axle box is prepared by being separated into an upper mold and a lower mold, and a core is provided in the lower mold After installing the core for forming, the step of merging by raising the upper mold; A molten metal injection step of injecting molten metal obtained by melting cast iron into the molding; When the injection of the molten metal corresponding to the capacity of the molding is completed, the molten metal injected into the molding is cooled and solidified for a preset time, and then demolded in the molding to obtain the casting maintaining the molding pattern; and, after heat-treating the casting at a preset temperature, a quality inspection step of performing a quality inspection of the casting by performing a non-destructive test on the casting.

In the above-mentioned molten metal injection step, it is preferable to arrange the injection hole of the earth pipe for injecting the molten metal into the molding at the lower side of the molding, and to inject the molten metal by a bottom injection method that fills up the molten metal from the bottom of the molding.

In addition, in the above-described molten metal injection step, a press installed to communicate with the inner cavity of the molding is provided, so that the molten metal corresponding to the capacity contracted as the molten metal is cooled and solidified is pressurized and supplemented, but the press is coupled to the axle in the upper mold of the molding It is preferable that three or more are provided in the area corresponding to the area.

In addition, when performing the above-described molten metal injection step, the molding is further provided with a chiller for accelerating the directional heat release rate, wherein the chiller is provided as a first chiller attached to the lower mold of the mold and a second chiller attached to the core The first cooling element is attached to the area corresponding to the seating area where the front and rear axle springs are seated in the lower mold of the molding, and the second cooling metal is attached to the area corresponding to the axle coupling area in the lower mold of the molding. It is preferable to do so.

In addition, when performing the above-described molten metal injection step, a gas vent (Gas Vent) for discharging gas generated during molten metal injection is further provided in the molding, and the gas vent is an axle coupling area, front and rear sides in the upper mold of the molding It is preferable to arrange in an area corresponding to the seating area where the axle spring is seated, so that three or more gas vents are provided.

In addition, in the above-described quality inspection step, performing a non-destructive inspection including at least one of a magnetic inspection (MT) and a radiographic inspection (RT) for the casting, to perform a quality inspection for the presence or absence of defects in the casting desirable.

In addition, as a result of performing the above-described quality inspection step, when a surface defect for the casting is found, by performing the surface treatment of the casting using a grinder, a machining step of processing the found surface defect in a mechanical way; further It is preferable to include

In addition, it is preferable to further include a preheating step of preheating the molding to a preset temperature before performing the above-described molten metal injection step.

According to an embodiment of the present invention, when casting an axle box provided to protect an axle, which is a device that supports the weight of a vehicle and transmits power to the wheels, casting of an axle box for a vehicle to minimize the occurrence of defects in the axle box It has the effect of being able to

In addition, according to an embodiment of the present invention, by providing a technique for casting an axle box using cast iron, the problem of poor castability of an axle box made of conventional cast steel and the problem of poor durability of an axle box made of aluminum It has a resolving effect.

In addition, according to an embodiment of the present invention, by injecting the molten metal into the molding in a lower injection method, it can function to minimize erosion and turbulence in the molding, and accordingly, the effect of improving the quality of the casting corresponding to the axle box there is.

In addition, according to an embodiment of the present invention, by installing a hot water, a chiller, and a gas vent in the molding in which the axle box is cast, the thermal gradient of the casting can be easily improved, the man-hours for removing the injection hole are saved, and the shrinkage hole A chiller to promote the solidification of the molten metal is installed in an area where there is a high risk of occurrence of molten metal, so that the solidification rate is uniformed, and bubble defects that adversely affect the mechanical properties of the casting can be minimized or prevented.

1 to 3 are examples of a flowchart of a casting method of an axle box for a vehicle.
Figure 4 is a form diagram of an axle box according to an embodiment of the present invention.
5 is a view showing an area in which a press is installed in an axle box according to an embodiment of the present invention.
6 is a view showing an area in which a chiller is installed in an axle box according to an embodiment of the present invention.
7 is a view showing an area in which a gas vent is installed in an axle box according to an embodiment of the present invention.

Hereinafter, various embodiments and/or aspects are disclosed with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of one or more aspects. However, it will also be recognized by one of ordinary skill in the art that such aspect(s) may be practiced without these specific details. The following description and accompanying drawings set forth in detail certain illustrative aspects of one or more aspects. These aspects are illustrative, however, and some of various methods may be employed in the principles of the various aspects, and the descriptions set forth are intended to include all such aspects and their equivalents.

As used herein, “embodiment”, “example”, “aspect”, “exemplary”, etc. may not be construed as an advantage or advantage in any aspect or design described above over other aspects or designs. .

Also, the terms "comprises" and/or "comprising" mean that the feature and/or element is present, but excludes the presence or addition of one or more other features, elements, and/or groups thereof. should be understood as not

Also, terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

In addition, in the embodiments of the present invention, unless otherwise defined, all terms used herein, including technical or scientific terms, are those commonly understood by those of ordinary skill in the art to which the present invention belongs. have the same meaning. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with the meanings in the context of the related art, and unless explicitly defined in the embodiment of the present invention, ideal or excessively formal meanings is not interpreted as

The present invention relates to a casting method of an axle box for a vehicle, and the present invention is to minimize the occurrence of defects in the axle box during casting of the axle box provided to protect the axle, which is a device that supports the weight of a vehicle and transmits power to the wheels. An object of the present invention is to provide a casting method of an axle box for a vehicle.

Meanwhile, the present invention will be described in more detail below with reference to the accompanying drawings, and some drawings may be simultaneously referenced to describe one or more technical features or components constituting the invention.

Referring to the flowchart of the casting method of the axle box for a vehicle with reference to FIG. 1, first, in the present invention, the molding 100 on which the pattern corresponding to the axle box is formed is prepared by being separated into an upper mold and a lower mold, and a core is formed in the lower mold. After the core is installed, the mixing step (S10) of raising the upper mold and mixing may be performed.

At this time, the modeling 100 is a model of an axle box with a casting sand, and it will be understood as a concept of a sand house in which molten metal, that is, molten metal is poured to produce an axle box, and the modeling 100 used in the present invention It may be understood that the modeling 100 is provided for manufacturing an axle box having the shape as shown in FIG. 4 .

Returning to FIG. 1 again, the above-mentioned core can be understood as a core member for making a casting with an empty interior, and if the installation is not stable, the core shakes or tilts, resulting in an abnormal shape of the casting, step S10 It would be desirable to perform a fixing operation for stabilization in

As an example of such a fixing operation of the core, a region in which the core is placed is separately provided on the lower mold and the upper mold of the molding 100 to fix the core, or a reinforcing bar is inserted inside the core and bolts are hung on the reinforcing bar to form 100 A method of fixing to the can be used.

In addition, a mold release agent may be applied to the mold 100 composed of the upper mold and the lower mold in step S10 to easily separate the casting obtained after the molten metal is injected, but the present invention is not limited thereto.

Next, after performing the above-described step S10, the molten metal injection step (S20) of injecting the molten metal obtained by melting cast iron into the mold 100 is performed.

As described above, in the present invention, cast iron is preferably used as the molten metal to be processed into molten metal, and such cast iron has a carbon solid solution limit of 1.7% or more among iron-carbon alloys (most preferably, a carbon solid solution limit of 2.0 to 4.5). %) and cast steel commonly used in castings such as axle boxes (carbon 0.1-0.5%, manganese 0.4-1.0%, silicon 0.2-0.4%, phosphorus 0.005% or less, sulfur 0.006% or less Compared to steel), castability is good, and it has excellent wear resistance, machinability, and damping ability to absorb vibrations of objects. It works.

In addition, in injecting the molten metal molten cast iron into the molding 100 in the step S20 described above, in the present invention, the injection hole of the earth pipe 10 for injecting the molten metal into the molding 100 is arranged at the lower side of the molding 100. , it is preferable to use a lower injection method that fills the molten metal from the bottom of the inner cavity of the molding 100. This lower injection method functions to minimize erosion and turbulence in the molding 100, thereby improving the quality of the casting. This has the effect of contributing to the reduction of the defect rate.

However, in this lower injection method, the solidification rate of the molten metal is slower in the area around the inlet of the earth pipe 10 into which the molten metal is injected than in other areas except for the inlet area of the earth pipe 10, so hot spots may occur. There is a concern that the defect of the shrinkage hole may be caused.

Therefore, in the present invention, in order to minimize the hot spots that may occur in the area around the inlet of the earth pipe 10, the inlet diameter of the earth pipe 10 is used as small as 20 to 40 mm to reduce the area where the hot spots can occur. desirable.

More preferably, the inlet diameter of the earth pipe 10 is 30 mm to minimize the area of occurrence of hot spots, and even more preferably, two or more earth pipes 10 are dispersed at a preset interval, and then the molding 100 By injecting molten metal into the molten metal, it would be desirable to maintain the solidification rate at a constant level to prevent the occurrence of hot spots and prevent the occurrence of shrinkage cavities.

As another embodiment, in the above-described step S20, the feeder 110 installed to communicate with the internal cavity of the modeling 100 may be provided, and the feeder 110 is cooled and solidified while the molten metal injected into the modeling 100 is cooled and solidified. It performs the function of replenishing the molten metal corresponding to the contracted capacity under pressure.

On the other hand, referring to FIG. 5 for explanation of the installation location of the feeder 110 , in FIGS. 5 a and b, the location at which the feeder 110 is installed is shown in the modeling 100 where the axle box pattern is formed. is indicated.

5a is a plan view of the design of the molding 100 for casting the axle box, and in FIG. 5b, the diagram of the molding 100 for casting the axle box is shown from a side cross-section. has been

As shown in FIGS. 5 a and b, at least three indentations 110 are triangular in the area corresponding to the axle coupling area 101 of the vehicle on the upper surface of the upper mold of the press-in 110 referred to in the present invention. It may be installed in a form to achieve a , and it is preferable that the shape of the feeder 110 is spherical.

In addition, in FIG. 5 b, the earth pipe 10 for injecting the molten metal in the lower injection method can be seen, and in the present invention, the thermal gradient of the casting is injected by the lower injection method into the molding 100 in which the press 110 is installed. can be easily improved, and the man-hours for removing the inlet can be saved.

On the other hand, in performing step S20 of FIG. 1 , in another embodiment of the present invention, the mold 100 may be further provided with a chiller 120 , which will be described with reference to the drawing of FIG. 6 at the same time. decide to go

The chiller 120 referred to in the present invention can be understood as a configuration for accelerating the directional heat release rate, and the chiller 120 of the present invention is preferably a first chiller 120 attached to the lower mold of the molding 100 . and a second chiller 120 attached to the core.

At this time, the above-described first chiller 120 may be respectively attached to regions corresponding to the seating regions 102 and 103 in which the front and rear axle springs are seated in the lower mold of the molding 100, and the second chiller described above. Reference numeral 120 is attached to a region corresponding to the axle coupling region 101 in the lower mold of the modeling 100 (in detail, a region corresponding to the length in which the vehicle axle is inserted into the axle box), and three or more The chiller 120 may have an attachment point.

The attachment point of the chiller 120 shown in FIG. 6 is a place where the thickness of the casting is not uniform, the supply of the molten metal does not reach only the feeder 110, or the place where the effect of the feeder 110 is expected to be insufficient. It can be understood that this is an area where shrinkage pore often occurs.

That is, in the present invention, it is possible to provide the effect of achieving uniformity of the solidification rate by installing the chiller 120 to promote the solidification of the molten metal in an area where there is a high risk of shrinkage.

On the other hand, as the material of the above-mentioned chiller 120, a material containing at least one of copper, steel, and cast iron may be preferably used, and in FIG. 6, the external chiller 120 attached to the outside of the mold 100 Although limitedly described, the design change of the molding 100 protrudes from the inner cavity of the molding 100 and thus fused with the casting, or the cooling material 120 is changed to an internal cooling material 120 that becomes a part of the casting and may be used. and the present invention is not limited thereto.

On the other hand, in another embodiment of the present invention, when step S20 of FIG. 1 is performed, the molding 100 may be further provided with a gas vent 130 for discharging gas generated when the molten metal is injected.

Specifically, the above-described gas vent 130 is configured to discharge air existing in the inner cavity of the modeling 100 or gas generated from the molten metal to the outside when the molten metal is injected into the inner cavity of the modeling 100 . can be understood, and the installation position of the gas vent 130 will be described with reference to FIG. 7 .

As shown in FIG. 7 , in the present invention, the gas vent 130 corresponds to the seating areas 102 and 103 in which the axle springs are seated, the axle coupling area 101 and the front and rear side axle springs of the upper die of the molding 100 . may be provided in each region, and at least three gas vents 130 are installed to smoothly discharge the bubbles generated inside the molten metal to the outside.

Meanwhile, in the present invention, due to the installation of the gas vent 130, there is an effect that it is possible to prevent bubble defects that adversely affect the mechanical properties of the casting.

Returning to FIG. 1 again, after performing step S20, when the injection of the molten metal corresponding to the capacity of the molding 100 is completed, the molten metal injected into the molding 100 is cooled and solidified for a preset time, and then the molding 100 By demolding in the casting acquisition step (S30) of obtaining a casting maintaining the pattern of the molding 100 is performed.

That is, the above-described step S30 removes at least any one of the hot metal 110 , the chiller 120 , and the gas vent installed in the molding 100 , and dismantles the molding 100 to form a casting corresponding to the shape of the axle box. It can be understood as obtaining

On the other hand, after performing the above-described step S30, a quality inspection step (S40) of heat-treating the casting at a preset temperature and performing a non-destructive inspection on the casting to perform a quality inspection of the casting is performed.

At this time, the above-mentioned heat treatment of the casting increases the toughness of the casting, strengthens the internal stress, and removes the non-uniform crystal structure by heating the demolded casting to a high temperature and then immersing it in water or oil to cool it at least once. there is an effect

In addition, the implementation of the non-destructive inspection on the casting in the above-described step S40, it is preferable to perform the non-destructive inspection using at least one inspection method of the magnetic inspection (MT) and radiographic inspection of the casting. .

Specifically, the magnetic flaw inspection described above is an inspection method that detects minute defects on the surface or inner surface of the casting by using the change in the magnetic force flux. A magnetic powder inspection method that allows the area to be visually identified may be used.

In addition, the above-mentioned radiographic inspection is a method of detecting defects by transmitting X-rays or gamma rays through the casting, and by observing the concentration of the transmission picture determined by the intensity of the attenuated radiation in the casting, defects in the casting are detected.

At this time, since the radiographic test is somewhat difficult to detect a flat defect raised vertically with respect to the transmitted radiation, in the present invention, the radiographic test and the magnetic flaw inspection described above are performed in parallel to determine the presence or absence of defects in the casting. It is desirable to perform a quality inspection for

On the other hand, in a preferred embodiment of the present invention, after performing the quality inspection step of step S40, when a surface defect for the casting is found as a result of the execution of step S40, in the present invention, the surface defect found in the casting using a grinder It may further include a processing step (S50) of machining in a mechanical manner.

At this time, the above-described step S50 may be performed more than once, and preferably, after performing step S50, the reliability of quality inspection of the axle box is improved by re-performing step S40 to verify whether the found defect is removed. It would be desirable to raise it.

Meanwhile, as another embodiment of the present invention, referring to FIG. 3 , the present invention may further include a preheating step (S11) of preheating the molding 100 to a preset temperature before performing the aforementioned step S20.

At this time, the preset temperature used for preheating of the above-described molding 100 may be performed at a temperature 30 to 50% lower than the injection temperature of the molten metal, for example, if the injection temperature of the molten metal is 1400° C., the preheating temperature is to be made at a temperature of 700 to 980 ℃.

On the other hand, the performance of step S11 can be understood as a pre-treatment process performed to reduce the chilling action of the casting obtained in the molding 100, and the above-described chilling action reduces the fluidity of the metal, such as wrinkles or air bubbles in the casting. It is preferable to perform sufficient preheating before injecting the molten metal into the molding 100 because it causes defects.

Moreover, in the present invention, since the effect of preheating the molding 100 in step S11 to minimize thermal damage caused by repeatedly contacting the molding 100 with the molten metal several times can be expected and seen, the above-described step S11 is It is desirable to include it in the casting process.

Overall, according to an embodiment of the present invention, when casting an axle box provided to protect an axle, which is a device that supports the weight of a vehicle and transmits power to the wheels, the axle box for a vehicle is designed to minimize the occurrence of defects in the axle box. It has the effect of being able to cast.

In addition, according to an embodiment of the present invention, by providing a technique for casting an axle box using cast iron, the problem of poor castability of an axle box made of conventional cast steel and the problem of poor durability of an axle box made of aluminum It has a resolving effect.

In addition, according to an embodiment of the present invention, by injecting the molten metal into the molding 100 in a lower injection method, it is possible to function to minimize erosion and turbulence in the molding 100, and accordingly, the casting corresponding to the axle box It has the effect of promoting quality improvement.

In addition, according to an embodiment of the present invention, by installing the hot water 110 , the chiller 120 , and the gas vent in the molding 100 in which the axle box is cast, the thermal gradient of the casting can be easily improved, and the injection hole is removed. In order to save the man-hours and to promote the solidification of the molten metal in the area where there is a high risk of shrinkage, the chiller 120 is installed to promote the uniformity of the solidification rate, and minimize the bubble defects that adversely affect the mechanical properties of the casting There is an effect that it can be prevented.

In addition, terms such as "comprises", "comprises" or "have" described above mean that the corresponding component may be embedded, unless otherwise specified, excluding other components. Rather, it should be construed as being able to further include other components. All terms, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, unless otherwise defined. Terms commonly used, such as those defined in the dictionary, should be interpreted as being consistent with the meaning of the context of the related art, and are not interpreted in an ideal or excessively formal meaning unless explicitly defined in the present invention.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (8)

In the casting method of an axle box for a vehicle,
A molding step of preparing a mold in which a pattern corresponding to the axle box is formed is separated into an upper mold and a lower mold, installing a core for forming a core in the lower mold, and raising the upper mold to form a mold;
a molten metal injection step of injecting molten metal obtained by melting cast iron having a carbon solid solution limit of 2.0 to 4.5% into the molding;
When the injection of the molten metal corresponding to the capacity of the molding is completed, the molten metal injected into the molding is cooled and solidified for a preset time, and then demolded in the molding to obtain a casting maintaining the pattern of the molding. step; and,
A quality inspection step of performing a quality inspection of the casting by performing a non-destructive inspection on the casting after heat-treating the casting at a preset temperature;
In the molten metal injection step,
The injection hole of the earth pipe for injecting the molten metal into the molding is disposed at the lower side of the molding, and the molten metal is injected in a lower injection method to fill up from the bottom of the molding,
The earth pipe uses that the diameter of the injection hole is 20 to 40 mm, and by dispersing two or more earth pipes at a preset interval and then injecting the molten metal into the molding, the occurrence of hot spots and shrinkage holes is minimized,
Provided with; a press installed so as to communicate with the internal cavity of the molding;
As the molten metal is cooled and solidified, the molten metal corresponding to the contracted capacity is pressurized and supplemented,
The press is
In the upper mold of the molding, three presses are installed in the area corresponding to the axle coupling area to form a triangle,
The molding is further provided with a chiller for accelerating the rate of directional heat release;
The cooling is
It is provided with a first chiller attached to the lower mold of the molding and a second chiller attached to the core,
The first cooling element is respectively attached to a region corresponding to a seating region in which the front and rear axle springs are seated in the lower mold of the molding,
The second coolant,
In the lower mold of the model, it is attached to an area corresponding to the axle coupling area so as to have at least three cooling attachment points,
When performing the molten metal injection step,
A gas vent (Gas Vent) for discharging gas generated when molten metal is injected is further provided in the modeling;
The gas vent,
In the upper mold of the molding, at least three are arranged in the area corresponding to the seating area where the axle springs are seated and the front and rear axle springs are disposed to discharge the bubbles generated inside the molten metal to the outside,
The quality inspection step is
Conducting a non-destructive inspection including magnetic inspection (MT) and radiographic inspection (RT) for the casting to perform a quality inspection for the presence or absence of defects in the casting,
As a result of performing the quality inspection step,
When a surface defect for the casting is found, by performing the surface treatment of the casting using a grinder, a processing step of processing the found surface defect in a mechanical manner; to be further included,
Before performing the molten metal injection step,
A preheating step of preheating the molding to a temperature 30 to 50% lower than the injection temperature of the molten metal is further included to reduce defects such as wrinkles or air bubbles in the casting obtained from the molding, and the molding and the molten metal several times A method of casting an axle box for a vehicle, characterized in that it minimizes thermal damage caused by repeated contact. delete delete delete delete delete delete delete

Images