CN106180643B - The extrusion casting method of casting - Google Patents

Abstract

The invention relates to a squeeze casting method for castings, which comprises the following steps: preheating the mold, pouring melt into the mold cavity; moving the upper mold downward to close the mold with the lower mold, and the first extrusion punch of the mold The head extrudes the melt of the first part, and the second extrusion punch of the mold extrudes the melt of the second part; the first extrusion punch and the second extrusion punch continue to move down, and Pressurize the extrusion force of the first extrusion punch and the second extrusion punch to the melt to f1 and hold the pressure for a time t1; the second extrusion punch continues to move down, and the second extrusion punch Continue to pressurize the melt at the second part, pressurize the extrusion force of the second extrusion punch to the melt to f2 and hold the pressure for a time t2, where f2>f1; open the mold and eject the casting. In the method, the casting is directly extruded twice in the same direction, and during the solidification process of the casting, the secondary extrusion is carried out in stages according to the solidification sequence of different parts of the casting, so as to improve the pressure distribution state and improve product quality and yield.

Description

Squeeze casting method for castings

technical field

The invention relates to the technical field of squeeze casting, in particular to a squeeze casting method for castings.

Background technique

Squeeze casting is a kind of metal processing that injects a certain amount of molten metal directly into the metal mold cavity, and then closes the mold to realize the filling and flow of the metal liquid, and undergoes high-pressure solidification and a small amount of plastic deformation under the action of mechanical static pressure to obtain blanks or parts. method. Castings are generally formed by one-time direct extrusion, but when pressing castings with complex structures, this pressure cannot be evenly distributed on the extrusion surface, and it cannot guarantee that the entire casting will solidify under the effective extrusion specific pressure. Especially when the thickness of different parts of the casting varies greatly in the vertical direction: in the process of direct extrusion casting, the parts with smaller thickness solidify before the parts with larger thickness, so that the extrusion pressure is mainly distributed in the parts with smaller thickness , and the thick part that needs to be solidified under continuous high pressure can only be distributed with less pressure, which is not conducive to the forming of the thick part and the improvement of the overall performance of the casting, especially as the thickness difference of the casting increases. The downside will be more pronounced.

Contents of the invention

The purpose of the present invention is to provide a squeeze casting method for castings, which can improve the pressure distribution state, facilitate the forming of parts with large thickness and improve the overall performance of castings.

For realizing the purpose of the present invention, the technical scheme that takes is:

A squeeze casting method for castings, which can realize secondary direct extrusion in the same direction for castings with uneven thickness. The casting includes a first part and a second part, the thickness of the first part is smaller than that of the second part, and the thickness of the first part is smaller than that of the second part. The method comprises the following steps:

(1), preheat the mold, and pour the melt into the mold cavity;

(2) The upper mold moves down to close the mold with the lower mold. The first extrusion punch of the mold squeezes the melt at the first part, and the second extrusion punch of the mold squeezes the melt at the second part. extrude the body;

(3), the first extrusion punch and the second extrusion punch continue to move downward, and pressurize the extrusion force of the first extrusion punch and the second extrusion punch to the melt to f1 and keep Pressing time t1;

(4), the second extrusion punch continues to move downwards, and the second extrusion punch continues to pressurize the melt at the second position, and the extrusion force of the second extrusion punch to the melt is boosted to f2 and holding time t2, where f2>f1;

(5) Open the mold and eject the casting.

In this method, the casting is directly extruded twice in the same vertical direction. During the solidification process of the casting, the secondary extrusion is carried out in stages according to the solidification sequence of different parts of the casting, so that the extrusion pressure can be increased during the alloy solidification process. Reasonable distribution, improving the pressure distribution state, increasing the local extrusion specific pressure and the effective time of pressure, effectively solving the problem that the thick part is not as dense as the thin part, and the grain is coarse, which is beneficial to the thick part. The improvement of the overall performance of molding and castings improves product quality and yield.

The technical scheme is further described below:

Further, in step (4), the extrusion force of the first extrusion punch on the first part is maintained at f1. Make the first extrusion punch continue to apply pressure to the melt of the first part, prevent deformation due to the pressurization of the second extrusion punch, and ensure product quality.

Further, in step (2) and step (3), the main hydraulic cylinder drives the first extrusion punch and the second extrusion punch to extrude the melt.

Further, in step (4), the secondary hydraulic cylinder drives the second extrusion punch to continue to pressurize the melt at the second location.

Further, in step (5), before the mold is opened, the auxiliary hydraulic cylinder first releases pressure, and then the main hydraulic cylinder releases pressure.

Further, in the step (3), the mold performs the first extrusion on the melt of the first part and the second part, and the specific pressure of the first extrusion is 50-150 MPa.

Further, in step (4), the second extrusion punch performs second extrusion on the melt at the second location, and the specific pressure of the second extrusion is 60-150 MPa.

Further, the pressure holding time t1 is 30-80s, and the pressure holding time t2 is 30-70s.

Further, in step (1), the preheating temperature is 150-250°C.

Further, the casting is a turbine, the first part is the rib plate, the second part is the rim of the turbine, the first extrusion punch is the upper mold core, and the second extrusion punch is the upper mold ring arranged around the upper mold core . The thickness of the ribs is thinner than that of the turbine rim. During the first extrusion, the upper die ring squeezes the turbine rim, and the ribs of the upper core are squeezed. When the ribs solidify After the completion, the upper die ring continues to move downward to pressurize the position of the turbine rim for secondary extrusion, so as to achieve the effect of improving the pressure utilization efficiency and increasing the extrusion specific pressure of the turbine outer ring, so that the turbine outer ring is thicker. The large parts are solidified and formed under sufficient extrusion pressure to further improve the quality and service life of the worm gear.

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

In the present invention, through the secondary direct extrusion of the casting in the same vertical direction, during the solidification process of the casting, the secondary extrusion is carried out in stages according to the solidification sequence of different parts of the casting, so that the extrusion pressure can be increased during the alloy solidification process. Reasonable distribution, improving the pressure distribution state, increasing the local extrusion specific pressure and the effective time of pressure, effectively solving the problem that the thick part is not as dense as the thin part, and the grain is coarse, which is beneficial to the thick part. The improvement of the overall performance of molding and castings improves product quality and yield.

Description of drawings

Fig. 1 is the schematic flow sheet of the extrusion casting method of casting of the embodiment of the present invention;

Fig. 2 is a schematic structural view of a vertical squeeze casting machine according to an embodiment of the present invention;

Fig. 3 is a structural schematic diagram of the mold of the embodiment of the present invention.

Explanation of reference signs:

10. The first template, 20. The movable template, 30. The second template, 40. The main drive cylinder, 50. The auxiliary drive cylinder, 510. The top plate, 610. The upper die, 611. The first extrusion punch, 612. The first Two extrusion punches, 613. upper die frame, 620. lower die, 621. lower die cover, 622. lower die core, 623. die cavity, 70. guide post, 80. driving mechanism.

Detailed ways

Embodiments of the present invention are described in detail below in conjunction with accompanying drawings:

As shown in Figure 1, a extrusion casting method for castings can realize secondary direct extrusion in the same direction for castings with uneven thickness. The casting includes a first part and a second part. The thickness of position is little, and this method comprises the following steps:

(1), preheat the mold, and pour the melt into the mold cavity;

(2) The upper mold moves down to close the mold with the lower mold. The first extrusion punch of the mold squeezes the melt at the first part, and the second extrusion punch of the mold squeezes the melt at the second part. extrude the body;

(3), the first extrusion punch and the second extrusion punch continue to move downward, and pressurize the extrusion force of the first extrusion punch and the second extrusion punch to the melt to f1 and keep Pressing time t1;

(4), the second extrusion punch continues to move downwards, and the second extrusion punch continues to pressurize the melt at the second position, and the extrusion force of the second extrusion punch to the melt is boosted to f2 and holding time t2, where f2>f1;

(5) Open the mold and eject the casting.

In this method, the casting is directly extruded twice in the same vertical direction. During the solidification process of the casting, the secondary extrusion is carried out in stages according to the solidification sequence of different parts of the casting, so that the extrusion pressure can be increased during the alloy solidification process. Reasonable distribution, improving the pressure distribution state, increasing the local extrusion specific pressure and the effective time of pressure, effectively solving the problem that the thick part is not as dense as the thin part, and the grain is coarse, which is beneficial to the thick part. The improvement of the overall performance of molding and castings improves product quality and yield.

In this embodiment, the casting is a turbine, the first part is the rib plate, the second part is the rim of the turbine, the first extrusion punch is the upper die core, and the second extrusion punch is the upper die core arranged around the upper die core. die ring. The thickness of the ribs is thinner than that of the turbine rim. During the first extrusion, the upper die ring squeezes the turbine rim, and the ribs of the upper core are squeezed. When the ribs solidify After the completion, the upper die ring continues to move downward to pressurize the position of the turbine rim for secondary extrusion, so as to achieve the effect of improving the pressure utilization efficiency and increasing the extrusion specific pressure of the turbine outer ring, so that the turbine outer ring is thicker. The large parts are solidified and formed under sufficient extrusion pressure to further improve the quality and service life of the worm gear.

In step (1), the preheating temperature of the mold cavity is 150-250°C.

In step (2), the main hydraulic cylinder drives the first extrusion punch and the second extrusion punch to extrude the melt.

In step (3), the main hydraulic cylinder is pressurized to a certain pressure and maintained for 30-80s, and the first extrusion punch and the second extrusion punch are used to extrude the melt for the first time. The specific pressure is 50-150MPa.

In step (4), the auxiliary hydraulic cylinder is pressurized to a certain pressure and maintained for 30-70s, and the second extrusion punch is used to extrude the melt in the second part, and the second extrusion pressure It is 60-150MPa; during this process, the main hydraulic cylinder continues to maintain the pressure of the first extrusion specific pressure until the second extrusion is completed, so that the first extrusion punch continues to melt the first part. body pressure to prevent deformation due to the pressurization of the second extrusion punch and ensure product quality.

In step (5), when the melt of the casting is completely solidified, the auxiliary hydraulic cylinder releases the pressure first, and then the main hydraulic cylinder releases the pressure, and then the lifting hydraulic cylinder drives the upper mold to move upward to open the mold, and the auxiliary hydraulic cylinder pushes out the casting and return.

In this embodiment, the casting is a turbine, the first part is the rib plate, the second part is the rim of the turbine, the first extrusion punch is the upper die core, and the second extrusion punch is the upper die core arranged around the upper die core. die ring. The thickness of the ribs is thinner than that of the turbine rim. During the first extrusion, the upper die ring squeezes the turbine rim, and the ribs of the upper core are squeezed. When the ribs solidify After the completion, the upper die ring continues to move downward to pressurize the position of the turbine rim for secondary extrusion, so as to achieve the effect of improving the pressure utilization efficiency and increasing the extrusion specific pressure of the turbine outer ring, so that the turbine outer ring is thicker. The large parts are solidified and formed under sufficient extrusion pressure to further improve the quality and service life of the worm gear.

Taking casting turbine as an example, the squeeze casting method specifically includes the following steps:

(1) ZA27 alloy is smelted, slag-removed, degassed, and the holding temperature is 630°C;

(2) Preheat the mold cavity to 200°C;

(3), inject 30Kg alloy melt into mold cavity;

(4) The main hydraulic cylinder drives the upper mold core and the upper mold ring to close the mold downward, and the descending speed is 8mm/s;

(5) After the mold is closed, the main hydraulic cylinder is pressurized and maintained, and the entire worm wheel is squeezed for the first time, and the worm wheel is solidified under pressure, and the extrusion specific pressure is 65MPa;

(6) After the main hydraulic cylinder maintains the pressure for 50s, the auxiliary hydraulic cylinder pressurizes to drive the upper die ring to squeeze downwards, the extrusion specific pressure of the worm wheel flange is 90MPa, and the pressure maintaining time is 60s;

(7) After the auxiliary hydraulic cylinder is pressure-holding, the pressure is released, and then the main hydraulic cylinder is released;

(8) The lifting hydraulic cylinder drives the upper mold to move upward to open the mold;

(9) The auxiliary hydraulic cylinder ejects the casting and returns to its position.

Compared with the metal mold gravity casting method generally used for zinc alloy worm gears, the worm wheel blanks produced by the method of the present invention have the advantages of compact structure, excellent mechanical properties, and small machining allowance. The production cost is reduced while improving the quality of the casting, suitable for mass production, and has positive technical application and promotion value.

As shown in Figure 2 and Figure 3, the present invention also provides a vertical squeeze casting machine for casting using the above method, the vertical squeeze casting machine includes a mold, a first template 10 arranged oppositely from top to bottom , the movable template 20 and the second template 30, and the main driving cylinder 40 fixed on the first template 10 and the auxiliary driving cylinder 50 fixed on the movable template 20, the mold includes an upper mold 610, a lower mold connected with the second template 30 Die 620, upper mold 610 comprises the first extruding punch 611 that is connected with movable platen 20, and the second extruding punch 612 that is connected with the piston rod of secondary drive cylinder 50, the piston rod of main drive cylinder 40 and movable platen 20 connections.

The first extrusion punch 611 of the mold corresponds to the position where the thickness of the casting is thinner, and the second extrusion punch 612 corresponds to the position where the thickness of the casting is thicker. During casting, the alloy melt is poured into the mold, and the main drive cylinder 40 The piston rod drives the movable template 20 to move downward, and at the same time drives the upper mold 610 to move downward and close the mold with the lower mold 620. The first extrusion punch 611 and the second extrusion punch 612 of the upper mold 610 simultaneously extrude the casting, After the mold is closed, the main driving cylinder 40 is pressurized and maintained, so that the whole casting is solidified under high pressure, and the first extrusion of the casting is realized; after the main driving cylinder 40 maintains the pressure for a certain period of time, the auxiliary driving cylinder 50 drives the first extrusion through the piston rod. The second extrusion punch 612 squeezes the thicker part of the casting downward, and the auxiliary drive cylinder 50 pressurizes and maintains the pressure, so that the thicker solidified part of the casting is still solidified under high pressure, realizing the second extrusion of the casting . The vertical squeeze casting machine realizes direct squeeze casting with secondary high pressure in the same vertical direction, so as to ensure that castings with uneven thickness can be solidified sequentially under the effective extrusion specific pressure, thereby improving product quality and yield. At the same time, due to the adoption of two high-pressure extrusion drive cylinders in series linkage, the overall structure of the casting machine is compact, the volume is small, the manufacturing cost is low, and it is easy to install and maintain. Similarly, when there are n casting parts with large thickness differences, the Lise squeeze casting machine is equipped with n driving cylinders according to actual needs, and n-1 moving platen 20 is set according to actual needs, and according to the solidification sequence of different parts of the casting Sequentially, the extrusion is carried out in stages.

In this embodiment, as shown in FIG. 3 , the first extrusion punch 611 is an upper die core, the second extrusion punch 612 is an upper die ring arranged around the upper die core, and the upper die 610 also includes an upper die frame 613, the upper mold frame 613 is connected with the movable template 20, the upper mold core is fixed on the upper mold frame 613, the lower mold 620 includes a lower mold cover 621 fixed on the second template 30, and a lower mold cover 621 fixed on the lower mold cover 621. The mold core 622, the lower mold core 622 is provided with the mold cavity 623 matched with the upper mold core and the upper mold ring, so that it is suitable for the casting of castings with a small center thickness and a large outer ring thickness, especially for the casting of turbines, and solves the problem of turbines. The structure of the outer ring is not as dense as that of the ribs and the grains are coarse. The mold can also be set in other forms according to the shape of the casting.

As shown in FIG. 2 , the vertical squeeze casting machine further includes a top plate 510 connected to the piston rod of the auxiliary drive cylinder 50 , and a second extrusion punch 612 connected to the top plate 510 . The piston rod of the auxiliary driving cylinder 50 is connected with the second extruding punch 612 through the top plate 510, which is convenient for installation and maintenance.

As shown in FIG. 2 , a guide post 70 is connected between the first formwork 10 and the second formwork 30 , and the movable formwork 20 is provided with a guide hole (not marked in the drawings) matching with the guide post 70 . The guide post 70 guides the movement of the movable template 20, making the movable template 20 more stable in the process of moving up and down, avoiding deviation, and making mold clamping more accurate.

In this embodiment, there are two groups of guide pillars 70, and the two groups of guide pillars are arranged front and back, and each group of guide pillars includes two guide pillars 70, so that the moving template 20 is more balanced and stable during the up and down movement.

As shown in FIG. 2 , the vertical squeeze casting machine also includes a driving mechanism 80 for driving the movable template 20 to move up and down, and the driving mechanism 80 is arranged on the first template 10 . When opening the mold, the driving mechanism 80 drives the movable platen 20 to move upwards to open the mold, and the auxiliary drive cylinder 50 drives the top plate 510 to eject the casting, which makes the mold opening more convenient and makes the overall structure of the vertical squeeze casting machine more compact.

In this embodiment, the driving mechanism 80 is a lifting hydraulic cylinder, and the piston rod of the lifting hydraulic cylinder is connected with the movable template 20 . The main driving cylinder 40 and the auxiliary driving cylinder 50 are also hydraulic cylinders, and the main driving cylinder 40, the auxiliary driving cylinder 50 and the driving mechanism 80 can also adopt other driving forms according to actual needs.

The maximum extrusion force of the main drive cylinder 40 is greater than the maximum extrusion force of the auxiliary drive cylinder 50. In this embodiment, the maximum extrusion force of the main drive cylinder 40 is 1000 tons, and the maximum extrusion force of the auxiliary drive cylinder 50 is 800 tons. Ton.

The present invention realizes the secondary extrusion of the casting in the same vertical direction through the vertical squeeze casting machine. During the solidification process of the casting, the secondary extrusion is carried out in stages according to the solidification sequence of different parts of the casting, so that the extrusion The pressure is distributed reasonably during the solidification process of the alloy, which improves the local extrusion specific pressure and the effective time of the pressure, and effectively solves the problems of dense structure and coarse grains in the thicker parts than the thinner parts, which is beneficial to the thicker parts. The molding of the parts and the improvement of the overall performance of the casting improve the product quality and yield; and the driving cylinder of the casting machine adopts a series linkage method, which makes the overall volume smaller and the structure more compact.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (8)

1. A squeeze casting method for a turbine, the turbine comprises a first part and a second part, the first part is a rib plate, and the second part is a turbine rim, it is characterized in that the method comprises the following step: (1), preheat the mold, and pour the melt into the mold cavity; (2) The upper mold moves down to close the mold with the lower mold. The first extrusion punch of the mold squeezes the melt at the first part, and the second extrusion punch of the mold squeezes the melt at the second part. extrude the body; (3), the first extrusion punch and the second extrusion punch continue to move downward, and pressurize the extrusion force of the first extrusion punch and the second extrusion punch to the melt to f1 and keep Pressing time t1; (4), the second extrusion punch continues to move downwards, and the second extrusion punch continues to pressurize the melt at the second position, and the extrusion force of the second extrusion punch to the melt is boosted to f2 and holding time t2, where f2>f1; (5) Open the mold and eject the casting; In step (2) and step (3), the first extrusion punch and the second extrusion punch are driven by the main hydraulic cylinder to extrude the melt; in step (4), the second extrusion punch is driven by the auxiliary hydraulic cylinder The second extrusion punch continues to pressurize the melt at the second position. 2 . The squeeze casting method for a turbine according to claim 1 , characterized in that, in step (4), the extrusion force of the first extrusion punch on the first part is maintained at f1 . 3 . The squeeze casting method for turbine according to claim 1 , characterized in that, in step (5), before the mold is opened, the secondary hydraulic cylinder is depressurized first, and then the main hydraulic cylinder is depressurized. 4. The squeeze casting method of turbine according to claim 1, characterized in that, in step (3), the mold carries out the first extrusion to the melt of the first part and the second part, and the first extrusion The specific pressure is 50-150MPa. 5. The squeeze casting method of turbine according to claim 1, characterized in that, in step (4), the second extrusion punch carries out second extrusion to the melt at the second position, and the second extrusion The extrusion specific pressure is 60-150MPa. 6 . The squeeze casting method for a turbine according to claim 1 , characterized in that the holding time t1 is 30-80s, and the holding time t2 is 30-70s. 7. The squeeze casting method for turbine according to claim 1, characterized in that, in step (1), the preheating temperature is 150-250°C. 8. The squeeze casting method for a turbine according to any one of claims 1 to 7, wherein the first extrusion punch is an upper mold core, and the second extrusion punch is arranged around the upper mold core upper die ring.