Wheel antigravity casting equipment with crucible heat preservation stove
阅读说明：本技术 一种带有坩埚保温炉的车轮反重力铸造设备 (Wheel antigravity casting equipment with crucible heat preservation stove ) 是由 张虎 张花蕊 于 2020-08-20 设计创作，主要内容包括：本发明公开了带有坩埚保温炉的车轮反重力铸造设备,包括模具和坩埚保温炉,坩埚保温炉内设有坩埚,坩埚内盛有金属熔体,炉体上设有电加热装置,测温热电偶,两侧升液管,高压气源；两侧升液管上方连接浇口杯和浇口套,浇口杯与下方的两侧升液管连通,浇口套对应于车轮模具轮辋正下方的位置,与浇入模具型腔用的型腔入口相连通,并将上升的金属熔体压边浇注入型腔。本发明适应于浇口设置在车轮的轮辋正下方的多浇口边注方式,解决了传统大尺寸车轮单升液管技术长距离补缩效果差、强化冷却后难以控制凝固温度场的难题,提高了车轮的性能及生产稳定性,还缩短了生产节拍,提高了生产效率和车轮的合格率。(The invention discloses a wheel antigravity casting device with a crucible holding furnace, which comprises a mold and the crucible holding furnace, wherein a crucible is arranged in the crucible holding furnace, a metal melt is filled in the crucible, and an electric heating device, a temperature measuring thermocouple, two side liquid rising pipes and a high-pressure air source are arranged on a furnace body; and the sprue cup and the sprue bush are connected above the liquid lifting pipes on the two sides, the sprue cup is communicated with the liquid lifting pipes on the two sides below the sprue cup, the sprue bush corresponds to the position right below the rim of the wheel mold and is communicated with a cavity inlet for pouring into a cavity of the mold, and the raised metal melt is subjected to edge pressing and pouring into the cavity. The invention is suitable for a multi-gate side pouring mode that the gates are arranged right below the wheel rim of the wheel, solves the problems of poor long-distance feeding effect and difficulty in controlling a solidification temperature field after intensive cooling of the traditional large-size wheel single lift tube technology, improves the performance and production stability of the wheel, shortens the production beat, and improves the production efficiency and the qualification rate of the wheel.)
1. The anti-gravity casting equipment for the wheels with the crucible holding furnace is characterized by at least comprising the crucible holding furnace and a mold;
the crucible heat preservation furnace comprises a furnace body, wherein a heat preservation layer made of refractory materials is arranged on the inner wall of the furnace body, a crucible is arranged in the furnace body, a metal melt is filled in the crucible, an electric heating device is arranged in the furnace body, a furnace cover is arranged at the upper part of the furnace body, a temperature thermocouple is arranged on the furnace cover, the furnace cover is connected with liquid lifting pipes at two sides, and the furnace cover is connected with a high-pressure air; the thermocouple measures the temperature of the metal melt in the crucible heat-preserving furnace, the electric heating device is controlled to keep the temperature of the electric heating device at the mold filling temperature, and the high-pressure air source is used for enabling the metal melt to rise into the mold cavity.
The pouring assembly is connected above the liquid lifting pipes on the two sides and comprises a pouring cup and pouring gate sleeves, the pouring cup is communicated with the liquid lifting pipes on the two sides below the pouring cup, the pouring gate sleeves are arranged above the pouring cup and correspond to positions right below a wheel mold rim and are communicated with cavity inlets for pouring metal melt into a mold cavity, the metal melt which rises is poured into the mold cavity in a pressing mode, and the mold cavity inlets corresponding to the pouring gate sleeves are arranged on a circular ring surface right below the wheel rim.
2. The antigravity casting apparatus with a crucible holding furnace as claimed in claim 1, wherein the sprue bush and the cavity entrance are disposed on the annular surface at positions corresponding to the outside of the window region and the rim and the spoke.
3. The wheel antigravity casting device with the crucible heat preservation furnace as claimed in claim 1, wherein the heat preservation layer is also arranged below the furnace cover, and a feeding port is formed in one side of the furnace cover and used for adding aluminum liquid.
4. The wheel antigravity casting apparatus with crucible holding furnace of claim 1, wherein the bottom of the furnace body is provided with rollers, and the rollers are located on the rail and can move along the rail.
5. The wheel antigravity casting apparatus with the crucible holding furnace as set forth in claim 1, wherein the cross-sectional shape of the sprue bush in communication with the cavity entrance is: including first segmental arc and second segmental arc, first segmental arc and second segmental arc are concentric, and the radius and the size of first segmental arc all are less than the second segmental arc, and first segmental arc and second segmental arc both sides are passed through the linkage segment and are connected.
6. The anti-gravity wheel casting equipment with the crucible holding furnace as claimed in claim 1, wherein the sprue bush and the sprue cup are positioned and installed through a step portion, a certain installation allowance is reserved between the outer wall of the sprue bush and the inner wall of the sprue cup, the lower opening of the sprue bush is communicated with the upper opening of the sprue cup, the upper opening of the sprue bush is a special-shaped opening and is communicated with an inlet of a mold cavity, a net placing groove is formed in the upper opening of the sprue bush and used for placing a filter net, and the lower opening of the sprue cup is communicated with a liquid lifting pipe.
7. The wheel antigravity casting apparatus with a crucible holding furnace as claimed in claim 6, wherein the filter screen has a cross-sectional shape identical to that of the liquid inlet passage.
Technical Field
The invention relates to the technical field of casting, in particular to a wheel antigravity casting device with a crucible holding furnace.
Background
The light weight is one of the most important ways for saving energy and reducing emission of fuel automobiles and reducing consumption and increasing range of new energy automobiles, and light weight materials such as aluminum alloy and the like are used for replacing traditional steel materials, so that the light weight materials become necessary choices for the updating of automobile design. Aluminum alloys used in automobiles can be classified into cast aluminum alloys and wrought aluminum alloys, and the cast aluminum alloys are mainly used for manufacturing parts such as engines, clutch housings, wheels, chassis parts, and the like. With the demand for improving the quality of castings and the development of casting technology, more parts are produced by adopting low-pressure casting, differential pressure casting and pressure-regulating casting, and all belong to anti-gravity casting methods. The basic principle of the casting is that low-pressure gas is used for driving metal melt in a crucible or a heat preservation furnace to rise through a riser tube and enter a mold cavity, and after mold filling is finished, the metal melt in the mold is solidified and fed under the action of pressure.
The traditional aluminum alloy low-pressure, differential-pressure and pressure-regulating wheel casting technology generally adopts a single-sprue single-riser tube mold filling technology. Taking an aluminum alloy wheel as an example, a riser tube is arranged at the center of the wheel, namely the wheel center of the wheel, so that metal melt enters a cavity and is filled and solidified. In order to refine the structure and eliminate the casting defects of shrinkage cavity, shrinkage porosity and the like, the cooling of a wheel mold is generally enhanced in the prior art by adopting water cooling, water mist cooling and the like, however, the enhanced cooling greatly shortens the solidification time of the wheel, for example, the solidification time of the large-size wheel after the enhanced cooling can be shortened to be within 100s, but the problem that the temperature field in the processes of cooling and solidifying the wheel in the production process is difficult to control is caused, so that the sequential solidification is difficult to realize, the product performance is unstable, and the qualification rate is low.
Other filling approaches have been attempted in the prior art for wheels. Patent CN201010107026.8 discloses a bilateral casting technology and device of aluminum alloy wheel low pressure casting sets up the runner in wheel both sides, makes aluminium liquid get into from rim, makes aluminium liquid crystallize to the rim by the wheel center under the mould temperature of quench through to cooling control, has shortened the distance that aluminium liquid flows, and the shrinkage porosity defect at R angle or rim position has been reduced in the cooperation cooling. Documents CN201310557627.2 and CN201410825962.0 disclose that a center gate and two side gates are combined to reduce the weight of the hub and improve the mechanical strength. CN201610390494.8 adopts a quick-witted bimodulus wheel hub mould, and the runner sets up on the rim position equally, realizes once pouring two wheel hubs.
However, the device and the method also have obvious defects, and for the mode that the aluminum liquid only enters from the rim, the inlet is arranged in the middle of the rim, and the aluminum liquid can be shunted after entering, namely the aluminum liquid is filled to the wheel center and the wheel edge at the same time, so that the filling time at each position is uncontrollable, the solidification sequence is uncontrollable, and the defects of shrinkage cavity and shrinkage porosity are easily formed. And for the mode of combining the central gate and the gates at two sides, because the aluminum liquid enters from the two inlets, confluence can be formed at the middle position, and cold shut and the like are easily caused by reasons such as unsmooth gas discharge and the like.
The applicant designs a multi-riser-tube-based rapid sequential solidification wheel forming device and method, wherein a pouring gate of a mold is arranged right below a rim of a wheel or outside an upper R corner of a lower wheel flange. The problem of long-distance feeding after filling is solved by the liquid lifting and filling of a plurality of liquid lifting pipes. However, the position and shape of the pouring gate are changed, and the traditional circular pouring component can not be adopted for mold filling, so that how to adopt a reasonable heat preservation furnace for heating and a matched pouring device to realize stable mold filling in the mode becomes a problem to be solved urgently.
Disclosure of Invention
In order to solve the technical problem, the invention provides wheel differential pressure casting equipment with a crucible holding furnace.
The complete technical scheme of the invention comprises the following steps:
the anti-gravity casting equipment for the wheels with the crucible holding furnace is characterized by at least comprising the crucible holding furnace and a mold;
the crucible heat preservation furnace comprises a furnace body, wherein a heat preservation layer made of refractory materials is arranged on the inner wall of the furnace body, a crucible is arranged in the furnace body, a metal melt is filled in the crucible, an electric heating device is arranged in the furnace body, a furnace cover is arranged at the upper part of the furnace body, a temperature thermocouple is arranged on the furnace cover, the furnace cover is connected with liquid lifting pipes at two sides, and the furnace cover is connected with a high-pressure air; the thermocouple measures the temperature of the metal melt in the crucible heat-preserving furnace, the electric heating device is controlled to keep the temperature of the electric heating device at the mold filling temperature, and the high-pressure air source is used for enabling the metal melt to rise into the mold cavity.
The pouring assembly is connected above the liquid lifting pipes on the two sides and comprises a pouring cup and pouring gate sleeves, the pouring cup is communicated with the liquid lifting pipes on the two sides below the pouring cup, the pouring gate sleeves are arranged above the pouring cup and correspond to positions right below a wheel mold rim and are communicated with cavity inlets for pouring metal melt into a mold cavity, the metal melt which rises is poured into the mold cavity in a pressing mode, and the mold cavity inlets corresponding to the pouring gate sleeves are arranged on a circular ring surface right below the wheel rim.
The sprue bush and the cavity inlet can be arranged at the positions corresponding to the outer sides of the window areas on the circular ring surface, and can also be arranged at the positions corresponding to the connection of the wheel rims and the wheel spokes on the circular ring surface.
A heat preservation layer is also arranged below the furnace cover, a feeding port is formed in one side of the furnace cover, and the feeding port is used for adding aluminum liquid.
The bottom of the furnace body is provided with rollers which are positioned on the tracks and can move along the tracks.
The cross section shape that sprue bush and die cavity entry are linked together is: including first segmental arc and second segmental arc, first segmental arc and second segmental arc are concentric, and the radius and the size of first segmental arc all are less than the second segmental arc, and first segmental arc and second segmental arc both sides are passed through the linkage segment and are connected.
The sprue bush and the sprue cup are positioned and installed through the step portion, a certain installation allowance is reserved between the outer wall of the sprue bush and the inner wall of the sprue cup, the lower opening of the sprue bush is communicated with the upper opening of the sprue cup, the upper opening of the sprue bush is a special-shaped opening and is communicated with an inlet of a mold cavity, a net placing groove is formed in the upper opening of the sprue bush and used for placing a filter screen, and the lower opening of the sprue cup is communicated with a liquid lifting pipe.
The cross section of the filter screen is the same as that of the liquid inlet channel.
Compared with the prior art, the invention has the advantages that:
the applicant proposes a multi-riser tube-based rapid sequential solidification wheel forming device and method, wherein a pouring gate of a mold is arranged right below a rim of a wheel. By using the liquid lifting and filling of the plurality of liquid lifting pipes, the filling distance of the metal melt is shortened by more than half compared with the existing single liquid lifting pipe mode, the temperature of the metal mold can be reduced to be lower than 320 ℃ from the existing 420 ℃, the cooling speed and the cooling effect of the wheel are naturally accelerated, and the rapid sequential solidification is realized. Because the position and the shape of the pouring gate are changed, the traditional round pouring component can not be adopted for filling. The antigravity casting device of the crucible holding furnace is suitable for a multi-sprue side-pouring mode in which the sprue is arranged right below the rim of the wheel, and realizes a stable pouring and mold filling mode at the edge of the wheel. The filling distance of the metal melt can be shortened by more than half compared with the existing stage by matching with a multi-riser tube side-pouring mode, and the problem that the existing large-size wheel is difficult to be fed for a long distance is solved. And meanwhile, the solidification time is further shortened, and the production efficiency and the mechanical property of the wheel are obviously improved. Through the optimized two-section type filling and pressurizing process design, the metal melt in the initial filling stage flows stably, then the cavity is filled quickly, the advantage of quick filling of the multiple lift tubes is played, and the production efficiency is improved.
Drawings
FIG. 1 is a schematic structural diagram of a wheel antigravity casting apparatus with a crucible holding furnace according to the present invention.
Fig. 2 is a cross-sectional view of fig. 1.
FIG. 3 is a schematic view of the distribution of the gate sleeve on the torus right under the rim according to the present invention.
Fig. 4 is a schematic view of the structure of a pouring cup and a pouring cup sleeve of the invention.
Fig. 5 is a schematic view of a structure with a partial pressurizing and attenuating device.
Fig. 6 is a schematic view of a prior art wheel structure.
FIG. 7a shows a portion of the device of FIG. 1 that is susceptible to air entrapment during the filling process.
Fig. 7b is a partial enlarged view of fig. 7 a.
FIG. 7c is a schematic view of the slow charging sequence of FIG. 7 a.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
As shown in the figures 1-2, the wheel antigravity casting equipment with a crucible holding furnace of the invention, which takes low-pressure casting as an example, comprises a crucible holding furnace 1 and a
the crucible heat preservation furnace 1 comprises a furnace body, a
And a pouring assembly is connected above the liquid lifting pipes on the two sides, the pouring assembly comprises a pouring cup 8 and a
The bottom of the furnace body is provided with rollers which are positioned on the tracks and can move along the tracks. This is prior art and is not shown in the figure for simplicity of illustration.
The mold cavity inlet corresponding to each sprue bush is arranged on a
In particular, the sprue bush and the cavity entrance may be provided on the annular surface at positions corresponding to the outer sides of the window regions, or may be provided on the annular surface at positions corresponding to the connection of the rim and the spokes.
In particular, the cross-section of the sprue bush, which is in communication with the cavity entrance, is substantially conformal to the shape of the cavity entrance at the filling location of the mold.
Specifically, as shown in fig. 3, the cross-sectional shape of the
The length of first segmental arc is 72 ~ 76mm, and the length of second segmental arc is 76 ~ 80mm, and the length of both sides linkage segment is 8 ~ 12 mm.
The specific connection relationship between the pouring cup 8 and the pouring
The liquid inlet channel formed by the inner surface of the sprue bush is approximately following the shape of a cavity sprue at the mold filling position of the casting mold, and the shape of the liquid inlet channel is as the shape of the section of the
In a preferred embodiment, the filter screen has the same cross-sectional shape as the inlet passage.
The number of the sprue bush is two, and the sprue bush is symmetrically arranged on two sides of the wheel axis. The number of sprue bushings may also be greater than two, arranged around the wheel axis.
Particularly preferably, the mold further comprises a local pressurizing device arranged below the wheel center position of the corresponding wheel on the mold to promote feeding at the wheel center position, as shown in fig. 5, the local pressurizing device comprises a
In particular, the pressure driving mechanism may be a hydraulic cylinder, the pressure transmission mechanism may be a hydraulic rod, and the pressure applying mechanism may be a pressure block. The specific pressurizing process is to apply mechanical pressure of 1000-12000 KPa after the filling is finished. So that the aluminum liquid is solidified under extremely high pressure, and the defect of shrinkage cavity and shrinkage porosity formed at the position due to insufficient edge feeding pressure is prevented.
The thinning mechanism can be an ultrasonic thinning mechanism or a vibration thinning mechanism. If the
The anti-gravity wheel forming process used in conjunction with the present invention is described below.
Fig. 6 is a view showing a typical wheel construction in which the central position of the wheel is generally referred to as the center of the wheel, the portion of the wheel on the outside of the wheel is fitted and fitted with a tire, the portion supporting the tire is referred to as the rim, the portion mounted and connected to the center of the wheel axle, and the portion of the wheel supporting the rim is referred to as the spoke, with a window being left between the spokes in the prior art. The portion of the rim that holds and supports the tire orientation is called the rim.
In the existing production of low-pressure or differential-pressure cast aluminum alloy wheels, a liquid lifting pipe is almost arranged at the center wheel center of the wheel, a melt enters a cavity from a pouring gate at the wheel center through a heat insulation cup and a pouring component connected to the liquid lifting pipe, the melt is divided under the action of a dividing cone, the mold is sequentially filled along the sequence of the wheel center, a spoke, a rim and a rim, and the solidification is realized after the cavity is filled. Meanwhile, the area of the sprue is large, so that the mold filling speed is high. However, some problems caused by the above pouring and filling manner cannot be solved well all the time, for example, the gate distance is long, the filling distance is too long, the hot spot parts such as the connection of the rim and the spoke are very difficult to be fed, shrinkage cavities and shrinkage porosity are easy to form, and the problem that the production in the wheel industry is disturbed is solved. Although the cooling is enhanced by adopting water cooling, water mist cooling and the like to the part to realize sequential solidification, the wheel filling and the solidification time are short, so that the temperature field is difficult to control accurately, and waste products with a certain proportion are still generated inevitably.
In the prior art, a mode of bilateral pouring is adopted in the middle of the side surface of the rim, and the defects of shrinkage cavity and shrinkage porosity are easily formed due to uncontrollable filling and solidification sequences caused by filling and shunting.
The invention also discloses an antigravity casting process suitable for the mold filling mode, and because the pouring mold filling mode of the antigravity casting process is greatly changed compared with the prior art, the original mold filling mode and the original solidification process cannot be suitable for the antigravity casting process.
The method specifically comprises the following steps:
(1) liquid lifting: pressurizing the aluminum liquid in the heat preservation furnace through a high-pressure air source, so that the aluminum liquid rises to the position of the pouring gate along the liquid lifting pipe under the pressure, wherein the pressure rising speed at the stage is 2.8-4.0 KPa/s, and the pressure is increased to 20 KPa;
(2) filling a mold: continuously boosting to enable the aluminum liquid to enter the cavity through the pouring gate, wherein the filling stage is two-stage pressurization, the boosting speed of the first stage is 0.1-0.2 KPa/s, the time is 2-4 s, and then the second stage is started to boost quickly until the cavity is full, and the pressure reaches 35KPa at the moment;
the boosting speed P' in the second stage is determined as follows:
in the formula:
p' is the pressure increasing speed with the unit of kPa/s; h is the total height of the cavity and the unit is mm; rho is the density of the metal melt and has the unit of g/cm3(ii) a K is a resistance coefficient, and the value range of K is 1-1.5; t is preset mold filling time with the unit of s, preferably 10 s; 102 is a unit conversion coefficient; n is the number of the lift tubes, the value range of N is 2-6, the number can be selected according to the number of windows of wheels of different types, and 2-4 is preferred; and x is the liquid raising index of the steel plate, the value range is 0.2-0.8, and in the wheel type scheme adopted in the embodiment, the value is 0.5.
(3) And (3) crystallization, pressurization and pressure maintaining: after the mold filling is finished, the pressure is rapidly increased to 150KPa at the boosting speed of 8-10 KPa/and is maintained for 60-150 s, and the wheel solidification is finished.
(4) Pressure relief and air release: and (4) after the aluminum alloy wheel is solidified, relieving the gas pressure in the heat preservation furnace, and enabling the aluminum liquid which is not solidified at the riser tube and the pouring gate to flow back to the heat preservation furnace.
For the selection of the pressure increasing speed in the liquid lifting stage and the mold filling stage, the inner diameter of the liquid lifting pipe is fixed during liquid lifting, and turbulence is basically not generated, so that the metal melt can quickly lift to the position of a pouring gate by adopting the quick pressure increasing speed, and the liquid lifting time is shortened. In the mold filling stage, the complicated shapes of the cavity and the sprue are considered, in the traditional mold filling mode, because a mode of pouring from the position of the wheel center is adopted, the sectional areas of the liquid lifting pipe and the sprue are not greatly different, and the sectional area of the cavity at the wheel center is large, turbulence is not easy to generate, so that the mold filling and pressure boosting speed can be obtained by experience or experiment. The invention adopts the mould filling mode on the circular ring surface of the rim, the mould filling mode is an irregular conformal gate, the shape area difference between the liquid lifting pipe and the gate is large, and the space at the rim is small, so that turbulent air entrainment is easy to generate if the mould filling pressure is unreasonable, and the defect of air holes is caused. The mold filling pressure design in the prior art adopts a calculation mode in an ideal state and is corrected by combining a resistance coefficient and the like. No consideration is given to the change in the flow conditions caused by the change in the cross-sectional areas of the lift tube and the gate. Therefore, the ideal mold-filling boosting speed cannot be obtained by adopting the empirical formula in the prior art.
The present inventors have therefore studied the above problems in combination with the riser, the gate, the shape and cross-sectional area of the cavity above the gate, and the flow characteristics of the molten metal. It was found that for the wheel rim position, as indicated by the arrow in fig. 7a, there are two locations with significantly varying areas in the initial stage of the mold filling, as indicated by the arrow in fig. 7b, where the gas entrapment is very likely to form if turbulence is generated, and it was designed and calculated that the present invention employs two-stage pressurization, the first stage significantly reduces the pressure rise rate to allow the molten metal to flow smoothly in the initial stage of the mold filling, fills the above-mentioned areas to avoid gas entrapment, as shown in fig. 7c (where the arrow is the direction of the melt filling), and then enters the second stage for rapid pressure rise to shorten the mold filling time. In the second stage of the mold filling process, researches show that the mold filling stability and the number of the liquid lifting pipes are obviously related, and because the traditional mode of pouring from the position of the center of the wheel only has one liquid lifting pipe and one pouring gate, the rules can be obtained through tests and quantitative treatment can be carried out. In the mold filling mode of the invention, the number of the liquid lifting pipes and the gates can be 2 or more. Under the same pressure increasing condition, the flow rate at the pouring gate and the flow rate in the square cavity above the pouring gate can be obviously changed, so that the mold filling flow mode is uncontrollable. Therefore, the invention obtains the pressure boosting mode of the second stage through research, and as can be seen from the formula (1), the applicable pressure boosting speed can be gradually increased along with the increase of the number of the liquid lifting pipes in the same preset mold filling time, and the problems of turbulent air entrainment and the like can not be caused. The resistance coefficient value is related to the viscosity of molten metal, the complexity of a casting cavity and the like, the lower limit is taken when the resistance is small, and the upper limit is taken when the resistance is large.
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