CN1640586A - Thixotropic forming process and equipment for metal alloys - Google Patents

Abstract

The invention discloses a thixoforming process and equipment for metal alloy, wherein the thixoforming process comprises the following steps: 1) preheating the metal alloy block material by using a preheating device until the metal alloy block material can avoid the occurrence of recrystallized grains but is close to the temperature Tr of the metal alloy block material for recrystallization; 2) delivering the metal alloy slab stock into an injection unit in a high pressure cold chamber die casting machine at a temperature of Tr; 3) heating the metal alloy block again to a temperature Ts1 at which it is in a semi-solid paste state using an induction heating device in the injection device; 4) injecting the semi-solid pasty metal alloy block obtained in the step 3) into a die cavity of a high-pressure cold chamber die casting machine at a temperature Ts1, filling the die cavity and carrying out thixoforming. The process is additionally reheated in the injection unit of the die casting apparatus by means of induction heating coils to bring the metal alloy slab into a semi-solid state.

Description

Thixotropic forming process and equipment for metal alloys

technical field

The present invention relates to a high-pressure die-casting process and its equipment, more specifically, to a high-pressure cold-chamber die-casting process and its equipment for metal alloys.

Background technique

At present, the process and equipment for thixotropic deformation of metal alloys by means of high-pressure cold chamber die-casting equipment are to pre-heat the metal alloy to a semi-solid or semi-liquid state, and then transport it to the injection device of the high-pressure die-casting machine by the delivery device. , injected into the mold cavity to form.

Among them, preheating, as disclosed in patent EP 0,808,680 A1 and US 6,089,846, is to preheat the metal alloy block material located outside the injection device of the high pressure die casting machine to a temperature in a semi-solid state in a ceramic tube. It lies between the solidus temperature and the liquidus temperature. For example, the traditional magnesium alloy AZ91 is injection-formed in such a way that it is first heated to a temperature between 560°C and 590°C so that the magnesium alloy is in a semi-solid state before injection.

And the conveying process, as disclosed in the patents Fr 92/0008 3 and WO 92/11362, the conveying of the metal alloy block in the semi-solid state is carried out by means of a piston located in a duct completely located in the cooling chamber. chamber die casting machine injection device; also in the system described by Creeden, CorrenTl, Tims and Dax (Tooling Design for Semi-solid Metal Working, Transaction of the 18th Intlrnational Die Casting Congress and Exposition, NADCA, Indianapolis, the UniTld StaTls, p 373-380, 1995) the transfer of the metal alloy block in the semi-solid state is carried out by means of a complex and expensive multi-axis robot which transfers the metal alloy block from a die casting machine located in a high pressure cold chamber Take it out from the nearby induction melting furnace equipment, that is, the metal alloy block in the paste state is taken out by a special grasping tool covered with insulating material. At this time, the temperature of the metal alloy block is between the solidus temperature and the liquidus temperature Between, but the metal alloy block conveying speed with this robot is very slow, it takes about 10 seconds.

From the above, it can be seen that the existing high-pressure cold chamber die-casting process and its equipment have the following shortcomings:

1. Because the metal alloy block is in a semi-solid state with paste characteristics at such a high temperature, it is prone to oxidation during transportation;

2. In the process of falling in the relevant container of the injection device or the ejection sleeve, the metal alloy block in the pasty state is easily deformed under the action of its own weight, which may cause problems during the injection process;

Third, when applying these processes on magnesium alloys, for safety purposes, protective gases such as sulfur fluoride (SF ₆ ), carbon dioxide (CO ₂ ), argon and sulfur dioxide (SO ₂ ) must be used.

Existing equipment must have several groups of synchronously working inductance devices to adapt to the production speed, because for magnesium alloy AZ91, the heating time from room temperature to semi-solid temperature is close to 80 seconds, and for aluminum alloys, the heating time from room temperature The heating time to the semi-solid temperature is 140 seconds or more, a lengthy heating time that would not be compatible with the typical production speed of conventional high pressure cold chamber die casting equipment.

Contents of the invention

The main purpose of the present invention is to solve the problem that the metal alloy thixotropy forming process and equipment existing in the high-pressure cold chamber die-casting machine are easily oxidized due to high temperature and easily deformed due to its own weight during the transportation process.

Another object of the present invention is to solve the problem that protective gas needs to be fed into the existing process and equipment when it is used for magnesium alloy.

The metal alloy thixotropic forming process adopting high-pressure cold chamber die-casting machine comprises the following steps among the present invention:

1) Preheating the metal alloy block material with a preheating device until the metal alloy block material can avoid recrystallization particles but is close to the recrystallization temperature Tr of the metal alloy block material;

2) Transporting the metal alloy block material to the injection device in the high-pressure cold chamber die-casting machine at Tr temperature;

3) Utilize the induction heating device in the injection device to heat the metal alloy block again to the temperature Ts1 that makes it in a semi-solid paste state;

4) At the temperature Ts1, inject the semi-solid paste-like metal alloy block material in step 3) into the mold cavity of the high-pressure cold chamber die-casting machine, fill the mold cavity and perform thixotropic deformation.

The material of the metal alloy block is a thixotropic metal alloy, and the material of the thixotropic metal alloy can be AZ91, AM60, AM50, ZE33, ZE52, ZE55, AZ95 magnesium alloy obtained by continuous casting or hot or warm extrusion etc. It can also be A356, AlSi6Cu1Mg, AlMg5Si2, AlSi6Cu3Mg, A356, A357 aluminum alloys obtained by continuous casting or hot or warm extrusion.

The temperature Tr is higher than the room temperature Ta, but lower than the solidus temperature Ts of the metal alloy. The optimum temperature is close to but slightly lower than the recrystallization temperature of the metal alloy material, and the temperature Ts1 is lower than the liquidus temperature of the metal alloy. The phase line temperature Tl, but higher than the solidus line temperature Ts, that is, Ta<Tr<Ts<Ts1<Tl.

The thixoforming equipment of the metal alloy in the present invention includes a high-pressure cold chamber die-casting equipment and a preheating equipment, and the elastic sleeve of the high-pressure cold chamber die-casting equipment is provided with a device capable of reheating the metal alloy block. heated induction heating means, the axis of the induction heating means being the same as the axis of the ejection sleeve, and the preheating means for receiving the solid metal alloy block and preheating the solid metal alloy block in advance to an approximate The recrystallization temperature of the metal alloy material is lower than the solidus temperature of the metal alloy, and the preheating device is connected with the metal alloy block inlet of the injection device.

The elastic sleeve includes a pipe (C) connected to the mould, a pipe (A) with an inductive heating device, a pipe (B) for inputting metal alloy blocks, the pipe (A) and the pipes (B, C ) are on the same straight line.

The induction heating device is an induction coil with a rectangular or square section surrounding the catheter.

The injection device is drilled with a perforation for the supply of lubricant in solid powder form, so that the lubricant directly enters and resides in the ejection sleeve.

The high-pressure cold chamber die-casting equipment is provided with a detection device for detecting whether there is a metal alloy block in the injection device, so as to allow the movement of the piston for pushing the metal alloy block.

The high-pressure cold chamber die-casting equipment is provided with a tiny coil made of very thin copper wire, which is placed near but outside the induction heating device for measuring the frequency of the induction heating The state is changed in order to measure the fraction of the liquid phase in the semi-solid state, the axis of the tiny coil is substantially parallel to the axis of the induction heating device.

The pre-heating device is in the shape of a drum, and the outside of the drum-shaped pre-heating device is connected with the ejection sleeve.

The preheating device is composed of a conduit, and an inductance coil for preheating the metal alloy block from room temperature to below the recrystallization temperature of the metal alloy material is wrapped around the conduit, and the outlet of the conduit is connected to a The insulated inclined channels connected to the ejection sleeves meet.

Said preheating device consists of an advancing conveyor belt located inside an insulated pipeline, by means of which the metal alloy block is heated from room temperature to temperature Tr and transported to the inlet of the injection device.

The ejection sleeve is heated by a resistance element heating box arranged around and inside the metal part of the ejection sleeve.

The section of the catheter in the induction coil is square or rectangular.

The piston can be made of ceramic material, because the ceramic material can avoid the interference of the inductive heating magnetic field, so the piston made of ceramic material can be reheated when the metal alloy block is reheated by the inductance coil inside the ejection sleeve Does not retract. In addition, the piston can also be made of other materials. If the material cannot avoid the interference of the inductive heating magnetic field, it will be retracted to its original position before using the inductive coil inside the ejection sleeve to reheat the metal alloy block again.

Beneficial effect:

The thixotropic forming process of the metal alloy in the present invention is not carried out after the metal alloy block is heated until the metal alloy is between the solidus temperature and the liquidus temperature, but at a temperature lower than the solidus temperature, ideally Conveying at a temperature below but close to the recrystallization temperature of the metal alloy material, so that the conveyed metal alloy block material will fall in the injection device while still having solid characteristics that will not deform, thereby preventing deformation during the conveying process. Deformation problem.

The thixotropic forming process of the metal alloy in the present invention relies on the airtightness of the piston in the injection device, so that the metal alloy block is in a closed space when reheating, which can reduce the occurrence of oxidation.

Description of drawings

Fig. 1 is the flow chart of the thixotropic forming process of metal alloy among the present invention;

Fig. 2 is the simple schematic diagram of the thixotropic forming equipment of metal alloy among the present invention;

Fig. 3 is the structural representation of the thixotropic forming equipment of metal alloy among the present invention;

Fig. 4 is a schematic structural view of the first embodiment of the preheating device in the present invention;

Fig. 5 is a schematic structural view of the second embodiment of the preheating device in the present invention;

Fig. 6 is a schematic structural view of the third embodiment of the preheating device in the present invention.

Detailed ways

The specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Embodiment one

As shown in Figure 1, taking the magnesium alloy of AZ91 as example, the thixotropic forming process of metal alloy comprises the following steps among the present invention:

1) Using a preheating device to preheat the magnesium alloy block from room temperature to a temperature Tr close to but lower than the solidus temperature of the magnesium alloy at 437°C, such as 365°C, wherein the solidus temperature of the magnesium alloy is 437°C, The liquidus temperature is 595°C;

2) Transporting the magnesium alloy block material to the injection device of the high-pressure cold chamber die-casting equipment at Tr temperature;

3) Using the induction heating device in the injection device of the high-pressure cold chamber die-casting equipment to heat the magnesium alloy block material again to a temperature Ts1 between 560°C and 590°C, so that the magnesium alloy block material is in a semi-solid paste state;

4) Injection at temperature Ts1 Inject the semi-solid paste-like metal alloy in step 3) into the mold cavity of the high-pressure cold chamber die-casting equipment, fill the mold cavity and thixomorphize.

As shown in Figures 2 and 3, the equipment for thixotropic deformation of metal alloys in this embodiment includes a high-pressure cold chamber die-casting equipment 1 and a preheating device 2, wherein the high-pressure cold chamber die-casting equipment 1 includes an injection device 10 And a mold 11 for simulating a molded part, the mold 11 is connected to the outlet site of the injection device 10 .

The injection device 10 includes an ejection sleeve 101 and a piston 102 disposed inside the ejection sleeve 101, wherein the ejection sleeve 101 includes a pipeline C connected to the mold 11, a conduit A with an inductive heating device, and used for inputting magnesium. The pipe B of the alloy block, and the reinforcement members D and E used to clamp the pipe A, pipes B and C, the axes of the pipe A and the pipes B and C are on a straight line. The ejection sleeve 101 has an outlet portion 104 connected to the mold 11, and an inlet portion 105 for inputting the magnesium alloy block material 3. The conduit A in the ejection sleeve 101 is a non-magnetic stainless steel or quartz, transparent silicon , cermets, detachable pipes made of ceramics, the ceramics can be alumina, mullite, boron nitride, etc., or other refractory materials, the inner diameter of the conduit A is dti. The inductive heating device 103 is an inductive heating coil wrapped on the conduit A formed by winding a copper tube. The copper tube has a rectangular or square cross section, and the inductive heating coil can be disassembled. The ejection sleeve 101 is also surrounded by an insulating layer (not shown) made of refractory material to avoid heat loss through heat radiation.

The diameter dp of the piston 102 is smaller than the inner diameters of the pipes B and C by dc, and can slide in the ejection sleeve 101 .

A hole 106 is drilled at the end of the ejection sleeve 101 close to the outlet 104 , and the hole 106 is used to input lubricant in the form of solid powder, so that the lubricant directly enters and exists in the ejection sleeve 101 .

Near the periphery of the inductive heating coil 103, a tiny coil made of very thin copper wire is arranged. The axis of the induction heating coil is substantially parallel to the axis of the induction heating coil 103, that is, when the magnesium alloy block material begins to appear liquid above the solidus temperature, the frequency of the induction heating coil is changed, and when the magnesium alloy block material is heated to the temperature of the semi-solid phase , the detected frequency change state can be fed back, the applied inductive energy can be controlled, and a signal can also be emitted to command the plunger 102 in the injection device to start the injection operation.

As shown in Figure 4, the preheating device 2 includes an insulating shell 23, a drum 20, and a conveying device 24 for loading and transporting magnesium alloy block materials. For heating, the drum 20 has a notch 22 for delivering the preheated metal alloy block material to the injection device of the high-pressure cold chamber die-casting equipment. Realized without any creative effort, so no more detailed description. In addition, the specific structure of each component in the high-pressure cold chamber die-casting equipment has been disclosed in the patent US 6,089,846, and will not be described in detail.

In this embodiment, due to the high resistance caused by the low conductivity of the magnesium alloy, the magnesium alloy can be reheated from the temperature Tr to the temperature Ts1 quickly by using an inductance in the injection device, and the time required for this heating only needs 20 seconds or Less, and this time can be coordinated with the general industrial production speed of conventional high pressure cold chamber die casting equipment.

In this embodiment, the conveying operation is carried out at a temperature Tr, which is close to but lower than the solidus temperature of magnesium alloy, 437°C, that is, the magnesium alloy bulk material is preheated from room temperature to 365°C, and then transported to the high-pressure cooling chamber. In the injection device in the chamber die-casting equipment, the induction heating coil is further heated to a temperature Ts1 between 560 ° C and 590 ° C, so that it is in a semi-solid state, and the heating time required by the induction heating coil is only 20 seconds Or less, and it takes 80 seconds if the inductive heating is carried out directly from room temperature, so the heating time can be shortened and the cost can be reduced after using the process of the present invention.

In addition, since the present invention selects a temperature lower than the solidus temperature and slightly lower than the recrystallization temperature of the metal alloy material for transportation, before the injection operation, supplementary inductive heating is carried out in the injection device of the high-pressure cold chamber die-casting equipment , so that the bulk magnesium alloy will not undergo significant microstructural changes that would interfere with the formation of spherical structures upon supplemental inductive heating.

Embodiment two

As shown in Figure 1, taking the A356 aluminum alloy as an example, the thixotropic forming process of the metal alloy in the present invention comprises the following steps:

1) Using a preheating device to preheat the aluminum alloy block from room temperature to a temperature Tr close to but lower than the solidus temperature of the aluminum alloy at 510°C, such as 483°C, wherein the solidus temperature of the aluminum alloy is 510°C, The liquidus temperature is 615°C;

2) Transport the aluminum alloy block material to the injection device in the high-pressure cold chamber die-casting equipment at Tr temperature;

3) Using the induction heating device in the injection device of the high-pressure cold chamber die-casting equipment to heat the aluminum alloy block again to a temperature Ts1 between 560°C and 580°C, so that the aluminum alloy block is in a semi-solid paste state;

4) At the temperature Ts1, inject the semi-solid paste-like aluminum alloy in step 3) into the mold cavity in the high-pressure cold chamber die-casting equipment, fill the mold cavity and thixomorphize.

As shown in Figures 2 and 3, the equipment for thixotropic deformation of metal alloys in this embodiment includes a high-pressure cold chamber die-casting equipment 1 and a preheating device 2, wherein the high-pressure cold chamber die-casting equipment 1 includes an injection device 10 And a mold 11 for simulating a molded part, the mold 11 is connected to the outlet site of the injection device 10 .

The injection device 10 includes a pipe C connected to the mold 11, a pipe A with an inductive heating device, a pipe B for inputting aluminum alloy blocks, and a reinforcement member D for clamping the pipe A, pipes B, and C, E, the axes of conduit A and pipes B and C are on the same straight line. in:

The butt joint between conduit A and pipe C is made of standard steel SKD61 (JIS) or chromium molybdenum steel H13 (chromiummolybdenumsTlel) (FeCr5.0Mo1.2Si1.0Mn0.40V0.4C0.37). The inner diameter dti of catheter A is slightly larger than the inner diameter dc of tubing C, and catheter A mates with the slightly tapered end of tubing C at the injection site. Pipe B can be moved backward so that it can be quickly replaced in the event of a break using a standard component changer. Pipes C and B are restrained by large and heavy reinforcing members E and D, which may be large and heavy columns or parts with square, circular or prismatic cross-sections, which are separated by The inductive heating coil is far enough away that it will not affect the magnetic field of the inductive coil, and the use of these large and heavy reinforcing members can avoid any bending of the piston rod and allow the aluminum alloy block to cross pipe B, pipe A and pipe C was well guided.

Conduit A consists of a sleeve made of non-magnetic stainless steel, or made of quartz, transparent silicon, cermets, ceramics, where ceramics can be alumina, mullite, boron nitride, etc., or other Refractory material, an inductive heating coil formed by winding a copper tube is wrapped around the conduit A. The copper tube has a rectangular or square cross-section. The inductive heating coil can be disassembled and wrapped around the inductive heating coil There is an insulating layer (not shown) made of refractory material to avoid heat loss through thermal radiation.

Pipes B, C are made of steel, where F is an opening in pipe B for the passage of aluminum alloy blocks preheated to temperature Tr. G is an opening in conduit C for allowing a conduit to pass therethrough to supply solid powder lubricant to lubricate piston 102 .

The diameter of the piston 102 is dp, the inner diameters of the pipes B and C are dc, dc-dp=the gap between the piston and the pipe B, where dp<dc.

Since the thermal expansion of pipes B and C made of steel is much greater than that of conduit A, the inner diameter dc of pipe B must be smaller than the inner diameter dti of conduit A, otherwise there will be a gap from pipe B to conduit A due to thermal expansion. Step, and the step will affect the aluminum alloy block from pipe B into conduit A. Thus, db<dp<dc<dti, where db is the diameter of the aluminum alloy block.

The guiding device of the piston 102 is rigid enough to avoid any eccentricity or bending phenomenon during the injection stroke. Since the structure and driving device of the piston 102 are prior art, no detailed description will be given.

The diameter db of the aluminum alloy block must be about 0.1 mm smaller than the inner diameter dc of the pipe B.

Tubes B and C are heated using a resistive heating cartridge 108 .

The volume of the aluminum alloy block must correspond to the volume of the cavity minus the volume of the runners and gates.

At the opening F, a detection device must be provided to detect whether the aluminum alloy block is delivered well, and then the piston 102 can advance to inject the aluminum alloy block.

A tiny coil of very thin copper wire is placed outside the inductive coil wrapped around pipe A, the axis of the tiny coil is generally parallel to the axis of the inductive coil wrapped around pipe A, and is located in the vicinity of pipe A . Tiny coils are used to detect the frequency change of the induction heating coil when liquid begins to appear in the aluminum alloy block above the solidus temperature. That is, when the aluminum alloy block is heated to the temperature of the semi-solid stage, the detected frequency change can be fed back to control the applied inductive energy in order to control the amount of liquid phase in the metal alloy block, which also makes it possible to emit A signal is issued to command the plunger to start the injection operation.

As shown in Figure 5, the preheating device 2 includes a conduit, and an inductive heating device 27 is wound around the outer edge of the conduit 26. The inductive heating device 27 is used to heat the aluminum alloy block material 3 entering the conduit 26, and the aluminum alloy The block is heated from room temperature to temperature Tr. The preheating device 2 pushes the aluminum alloy block 3 forward in a conduit 26 heated by induction by means of a piston 28 . At the output end of said duct, the aluminum alloy block, at temperature Tr, slides on an insulated inclined channel 29, after which it rolls directly towards the opening F located in the upper part of the injection device.

In this embodiment, the aluminum alloy block material in a preheated solid state (that is, at a temperature Tr lower than the solidus temperature Ts) is transported to the injection device of the high-pressure cold chamber die-casting equipment, so that the aluminum alloy block material is produced by a The piston pushes forward to a heatable conduit A, as shown in Figure 3, the aluminum alloy block is in a closed environment in the heating conduit A by means of the sealing of the piston itself, and is isolated from the outside atmosphere, thus reducing the Oxidation, at the same time, because the aluminum alloy block is transported at the temperature Tr, since the temperature Tr is between the room temperature Ta and the solidus temperature of the aluminum alloy 510°C (Ts), it can prevent the aluminum alloy from occurring during the transportation process. out of shape.

In addition, the conduit A with heating function can also vacuumize the closed environment by installing a standard vacuum device. The standard vacuum device can be the device usually used for vacuuming the mold in high-pressure cold chamber die-casting equipment.

In this embodiment, because the aluminum alloy blocks are preheated in a solid state, this embodiment can have a faster reheating speed, which can be equivalent to the general output production speed of conventional high-pressure cold chamber die-casting equipment. Therefore, the reheating time required for heating the aluminum alloy block to the temperature Ts1 can be reduced, that is, the time required for inductive heating is only 20 seconds, and if it is not preheated to 483 ° C but directly from room temperature Inductive heating takes about 140 seconds.

In the above two embodiments, the used magnesium alloy and aluminum alloy are all thixotropic metal alloys, and the warm or hot metal alloy rods are extruded into metal alloy rods and sawed into multiple blocks. The length of these blocks is related to the utilization The required volume of the casting obtained by the thixotropic deformation process can also be used in continuous casting rods or directly cold casting rods in this process. The thixotropic metal alloy materials can be AZ91, AM60, AM50, ZE33, ZE52, ZE55, AZ95 magnesium alloy, also can be A356, AlSi6Cu1Mg, AlMg5Si2, AlSi6Cu3Mg, A356, A357 aluminum alloy.

In the above two embodiments, the preheating device 2 and the injection device 10 can be combined arbitrarily, and are applicable to magnesium alloys and aluminum alloys. The preheating device 2 can also have another structure, as shown in Figure 6, that is, use a A traveling carpet inside an insulated pipe heats the metal alloy block from room temperature to temperature Tr and conveys it to the inlet of the injection unit.

The specific operation steps in the above-mentioned two embodiments are further described below:

Step 1: using a preheating device to heat the metal alloy block from room temperature to a temperature Tr, and keep the metal alloy block at the temperature Tr;

Step 2: Input the metal alloy block material with temperature Tr into the inlet of the injection device, so that the piston moves forward, and push the metal alloy block material to the ceramic/quartz pipeline area, and the pipeline area is provided with an induction coil;

Step 3: The piston returns to the initial position so as not to affect the magnetic field used for inductive heating;

If the piston is replaced by a ceramic piston in this step, there is no need to go back in this stage, as the ceramic piston will not affect the magnetic field used for inductive heating.

Step 4: Preheating the metal alloy block material from the temperature Tr to the temperature Ts1 (Ts<Ts1<Tl) by using an induction heating device;

Step 5: Injecting the metal alloy block at temperature Ts1 to fill the mold cavity;

Step 6: Return the piston to the initial position to allow a new block of metal alloy to be loaded from the preheater.

To sum up, the thixotropic forming process and equipment of the metal alloy in the present invention are not transported to the injection device of the high-pressure cold chamber die-casting equipment at the temperature of the metal alloy block in a paste state, but are located at a temperature lower than the metal alloy Conveying at the solidus temperature, so that the conveyed metal alloy block will not deform when it falls in the injection device.

In addition, in the present invention, the temperature Tr at which the metal alloy lump is conveyed is lower than the recrystallization temperature TR, so that any change in structure, especially the appearance of recrystallized grains, can be avoided. And in any case, since the delivery temperature Tr is always lower than the solidus temperature Ts, any deformation of the metal alloy block in its preheating place, in the injection device and in the delivery process is avoided.

Claims (18)

1. the thixotropic forming technology of a metal alloy includes the following step:

1) utilizes preheating apparatus that metal alloy piece material is preheated, can avoid crystalline particle occurring up to metal alloy piece material again but the temperature T r of crystallization again takes place near metal alloy piece material;

2) under the Tr temperature, metal alloy piece material is delivered in the injection device in the high pressure cold-chamber die casting machine;

3) utilizing inductance heater in the injection device once more metal alloy piece material to be heated to makes it be in the temperature T s1 of semi-solid mushy stage;

4) under temperature T s1, the semi-solid starchy metal alloy piece material in the step 3) is injected in the die cavity of high pressure cold-chamber die casting machine loading mould cavity and thixotropic forming.

2. according to the thixotropic forming technology of the metal alloy described in the claim 1, it is characterized in that: the material of described metal alloy piece material is the thixotroping metal alloy.

3. according to the thixotropic forming technology of the metal alloy described in the claim 2, it is characterized in that: the material of described thixotroping metal alloy can be the AZ91 that obtains by continuous casting or heat or warm-extrusion forming, AM60, AM50, ZE33, ZE52, ZE55, AZ95 magnesium alloy or the like.

4. according to the thixotropic forming technology of the metal alloy described in the claim 2, it is characterized in that: the material of described thixotroping metal alloy can be the A356 that obtains by continuous casting or heat or warm-extrusion forming, AlSi6Cu1Mg, AlMg5Si2, AlSi6Cu3Mg, A356, A357 aluminium alloy or the like.

5. according to the thixotropic forming technology of the metal alloy described in the claim 1, it is characterized in that: described temperature T r is greater than room temperature Ta, and be lower than the solidus temperature Ts of metal alloy, and temperature T s1 is lower than the liquidus temperature T1 of described metal alloy, but be higher than solidus temperature Ts, i.e. Ta＜Tr＜Ts＜Ts1＜T1.

6. the thixotropic forming equipment of a metal alloy, include a cold high pressure constant pressure casting machine and and preheat equipment, it is characterized in that: described cold high pressure constant pressure casting machine is provided with the inductance heater that can heat again metal alloy piece material in launching of its injection device in the sleeve, the axis of this inductance heater is identical with the described axis that launches sleeve, described preheating apparatus is used to receive solid metal alloy block material, and this solid metal alloy block material preheated in advance to one near metal alloy compositions generation recrystallization temperature but be lower than the temperature of metal alloy solidus temperature, this preheating apparatus is connected with the metal alloy piece material inlet of described injection device.

7. according to the thixotropic forming equipment of the metal alloy described in the claim 6, it is characterized in that: described resilient sleeve includes the pipeline (C) that is connected with mould, the conduit (A) that has the inductance heater, be used to import the pipeline (B) of metal alloy piece material, the axis of conduit (A) and pipeline (B, C) is on same straight line.

8. according to the thixotropic forming equipment of the metal alloy described in the claim 7, it is characterized in that: described conduit is made by non-magnetic stainless steel or by quartz, transparent silicon, cermet, pottery, and described pottery is alum clay, mullite, boron nitride or other refractory material.

9. according to the thixotropic forming equipment of the metal alloy described in the claim 7, it is characterized in that: described inductance heater is to be looped around the described conduit of a newspaper inductance coil that has rectangle or square cross-section on every side.

10. according to the thixotropic forming equipment of the metal alloy described in the claim 7, it is characterized in that: be drilled with a perforation that is used to supply with the lubricant that is the pressed powder form on the described injection device, lubricant is directly entered and be present in described launching in the sleeve.

11. thixotropic forming equipment according to the metal alloy described in the claim 7, it is characterized in that: described cold high pressure constant pressure casting machine is provided with a sniffer, this sniffer is used for detecting described injection device and whether has metal alloy piece material, to allow to be used to promote the piston motion that metal alloy piece material is advanced.

12. thixotropic forming equipment according to the metal alloy described in the claim 7, it is characterized in that: described cold high pressure constant pressure casting machine is provided with a micro-coil of being made by very thin copper wire, this micro-coil is arranged near the described inductance heater, but be positioned at the outside of described inductance heater, be used to measure the variable condition of inductance frequency, so that measure the deal of liquid phase in the semi-solid state, the axis of this micro-coil is in substantially parallel relationship to the axis of described inductance heater.

13. the thixotropic forming equipment according to the metal alloy described in claim 6 or 7 is characterized in that: described preheating apparatus is the cylinder shape, the outside of the preheating apparatus of this cylinder shape is connected with the described sleeve that launches.

14. thixotropic forming equipment according to the metal alloy described in claim 6 or 7, it is characterized in that: described preheating apparatus is made of a conduit, be surrounded with one around this conduit and be used for metal alloy piece material is preheated to the inductance coil of the temperature that is lower than solidus temperature from room temperature, the outlet of described conduit and one are connected the adiabatic ramp way that launches on the sleeve and join.

15. thixotropic forming equipment according to the metal alloy described in claim 6 or 7, it is characterized in that: described preheating apparatus is a conveyer belt that advances that is positioned at an insulated piping inside, utilizes this conveyer belt that metal alloy piece material is heated to temperature T r and is delivered to the porch of injection device from room temperature.

16. the thixotropic forming equipment according to the metal alloy described in claim 6 or 7 is characterized in that: the described sleeve that launches is by being arranged on heating with inner resistive element heating box of this metal that launches sleeve part on every side.

17. the thixotropic forming equipment according to the metal alloy described in the claim 9 is characterized in that: the section of the conduit in the described inductance coil is square or rectangle.

18. thixotropic forming equipment according to the metal alloy described in claim 11 or 12, it is characterized in that: the making material of described piston be for can avoiding interference the ceramic material in inductance heating magnetic field, thereby the inductance coil that need not to launch in utilization sleeve inner carries out once more bouncing back in the heating process to metal alloy piece material.

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