JP7564643B2 - Die casting equipment and die casting method - Google Patents

Description

The present invention relates to a die casting device and a die casting method, and in particular to a die casting device equipped with a pressurizing means for pressurizing the runner of a die casting mold, and a die casting method performed using the die casting device.

A die casting device having a first plunger that fills the molten metal in the sleeve toward a cavity defined inside the die casting mold, and a second plunger that pressurizes the molten metal in the runner, is known from Patent Document 1 below. Patent Document 1 below suggests that the second plunger pressurizes the molten metal in the runner before, or preferably just before, the first plunger completes filling the cavity with the molten metal.

However, because the fluidity of the molten metal in the runner is good before the molten metal has completely filled the cavity, even if the die-casting device disclosed in Patent Document 1 below is used to pressurize the molten metal in the runner at this time, the molten metal will flow back through the gap between the second plunger and the surface that defines the runner, making it impossible to maintain the pressure.

Therefore, the applicant has invented the die casting device shown in the following Patent Document 2 in order to provide a die casting device with an excellent feeder effect when the runner is pressurized before the molten metal is completely filled into the cavity. This die casting device is equipped with a die casting mold that defines a cavity and a runner that communicates with the cavity, a first pressurizing means that fills the molten metal into the cavity, and a second pressurizing means that pressurizes the molten metal in the runner, the second pressurizing means being equipped with a pressurizing rod that advances and retreats in a direction approximately perpendicular to the mold opening direction of the die casting mold. With this die casting device, a sufficient feeder effect can be obtained even when the runner is pressurized before the molten metal is completely filled into the cavity, making it possible to improve the quality of the die cast product formed in the cavity.

JP 2000-117411 A JP 2011-224650 A

However, there is a constant demand for improved product quality in the industrial world, and there is a demand for a die casting apparatus and a die casting method using said die casting apparatus that have a more significant effect on improving the quality of die cast products. The present inventors have focused on the runner pressurization by the second pressurizing means for the die casting apparatus disclosed in the above-mentioned Patent Document 2, and have devised an improved technique for further improving the feeder effect. In other words, the present invention has been made to provide an improved technique for the die casting apparatus disclosed in Patent Document 2, and aims to provide a die casting apparatus and a die casting method using said die casting apparatus that can obtain a more effective feeder effect than the conventional technique when the runner is pressurized before the molten metal is completely filled into the cavity, thereby improving the quality of the die cast product formed in the cavity.

The present invention will be described below. Note that, to facilitate understanding of the present invention, reference numbers of the attached drawings are given in parentheses, but this does not mean that the present invention is limited to the illustrated form.

The die-casting device (1) according to the present invention comprises a die-casting die (10) that defines a cavity (53) and a runner (50) that communicates with the cavity (53), a first pressurizing means (24, 25) that fills molten metal into the cavity (53), and a second pressurizing means (40, 41, 43) that pressurizes the molten metal in the runner (50), the second pressurizing means (40, 41, 43) comprising a pressurizing rod (43) that advances and retreats in a direction substantially perpendicular to a mold opening direction of the die-casting die (10). The apparatus (1) is characterized in that, after injection of the molten metal into the cavity (53) by the first pressurizing means (24, 25) has started, and before the injection speed of the molten metal has completely decreased, the second pressurizing means (40, 41, 43) starts pressurizing the molten metal in the runner (50), and the first pressurizing means (24, 25) and the second pressurizing means (40, 41, 43) are configured to operate within a short time period in which solidification of the molten metal does not occur in the cavity (53) .

Another die-casting device (1) according to the present invention is a die-casting device (1) comprising a die-casting die (10) defining a cavity (53) and a runner (50) communicating with the cavity (53), a first pressurizing means (24, 25) for filling molten metal into the cavity (53), and a second pressurizing means (40, 41, 43) for pressurizing the molten metal in the runner (50), wherein the second pressurizing means (40, 41, 43) comprises a pressurizing rod (43) which advances and retreats in a direction substantially perpendicular to a mold opening direction of the die-casting die (10), and a pressure applying means for applying pressure to the molten metal in the runner (50) by the second pressurizing means (40, 41, 43) is configured to start pressurizing the molten metal in the runner (50) by the second pressurizing means (40, 41, 43) before the injection speed of the molten metal has completely dropped after the injection of the molten metal into the cavity (53) by the second pressurizing means (25) has started, and the position of the tip (43A) of the pressurizing rod (43) when the injection speed of the molten metal has completely dropped is configured to advance by 27% of the pressurizing rod stroke amount from when the pressurizing rod (43) starts pressurizing to when the flow path is blocked and a high pressure is generated in the cavity (53).

Another die-casting device (1) according to the present invention is a die-casting device (1) comprising a die-casting die (10) defining a cavity (53) and a runner (50) communicating with the cavity (53), a first pressurizing means (24, 25) for filling molten metal into the cavity (53), and a second pressurizing means (40, 41, 43) for pressurizing the molten metal in the runner (50), wherein the second pressurizing means (40, 41, 43) comprises a pressurizing rod (43) which advances and retreats in a direction substantially perpendicular to a mold opening direction of the die-casting die (10), and wherein after injection of the molten metal into the cavity (53) by the first pressurizing means (24, 25) has started, an injection speed of the molten metal is controlled by a control circuit. the second pressurizing means (40, 41, 43) starts pressurizing the molten metal in the runner (50) before the injection speed of the molten metal reaches its lowest point, and the first pressurizing means (24, 25) and the second pressurizing means (40, 41, 43) are configured to operate within a short time period in which solidification of the molten metal does not occur in the cavity (53) when the injection speed of the molten metal reaches its lowest point, and the position of the tip (43A) of the pressurizing rod (43) when the injection speed of the molten metal reaches its highest point is configured to advance by 27% of the pressurizing rod stroke amount from when the pressurizing rod (43) starts pressurizing to when the flow path is blocked and a high pressure is generated in the cavity (53).

The die casting method according to the present invention is characterized in that die casting is performed using any of the die casting devices (1) described above.

The present invention provides a die casting device that can achieve a better feeder effect than conventional techniques when the runner is pressurized before the molten metal is completely filled into the cavity, thereby improving the quality of the die cast product formed in the cavity, and a die casting method that uses the die casting device.

4 is a cross-sectional view showing a state in which the pressure rod is in a retreated position in the die casting device according to the embodiment. FIG. 4 is a cross-sectional view showing a state in which the pressure rod is in an advanced position in the die casting device according to the embodiment of the present invention. FIG. FIG. 2 is a graph illustrating a die casting method that can be performed by the die casting apparatus according to the present embodiment, showing the injection speed and the pressure rod stroke. FIG. 4 is a diagram showing the state of the die casting device at a location marked with the symbol (i) in FIG. 3 . FIG. 4 is a diagram showing the state of the die casting apparatus at the location indicated by the symbol (ii) in FIG. 3 . FIG. 4 is a diagram showing the state of the die casting apparatus at the location indicated by reference symbol (iii) in FIG. 3 . FIG. 4 is a diagram showing the state of the die casting apparatus at the location indicated by the reference symbol (iv) in FIG. 3 .

Below, preferred embodiments for carrying out the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

The die-casting device 1 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Here, Figure 1 is a cross-sectional view showing the die-casting device according to this embodiment with the pressure rod in the retracted position. Also, Figure 2 is a cross-sectional view showing the die-casting device according to this embodiment with the pressure rod in the advanced position.

As shown in FIG. 1, the die casting mold 10 includes a fixed mold 20 and a movable mold 30. The fixed mold 20 includes a fixed holder 21 and a fixed die 22, and an injection sleeve 23 (sleeve) is disposed in the fixed holder 21. A plunger tip 25 connected to the tip of a plunger rod 24 is disposed in the injection sleeve 23. By operating an injection cylinder (not shown) to slide the plunger tip 25 in the injection sleeve 23, molten metal such as an aluminum alloy supplied from a molten metal supply hole (not shown) of the injection sleeve 23 can be filled into a cavity 53 (described below). The plunger tip 25, the plunger rod 24, and the injection cylinder (not shown) constitute the first pressurizing means according to the present invention.

The movable mold 30 is composed of a movable holder 31, a movable die 32, and a flow divider 33, and can move in the moving direction of the movable mold 30 indicated by the arrows A←→A' (the mold opening direction of the die-casting mold 10). In the mold clamping state shown in FIG. 1 and FIG. 2, a runner 50, a gate 52, and a cavity 53 are defined inside the die-casting mold 10, and the space inside the sleeve 23 communicates with the cavity 53 via the runner 50 and the gate 52. The runner 50 includes a first runner 50A extending in a direction substantially coincident with the axial direction of the injection sleeve 23 (the mold opening direction of the die-casting mold 10), and a second runner 50B extending in a direction substantially perpendicular to the axial direction of the injection sleeve 23. The first runner 50A is defined by the injection sleeve 23 arranged in the fixed mold 20 and the flow divider 33 of the movable mold 30. The second runner 50B has a portion defined by the injection sleeve 23 and the diverter 33, and a portion defined by the fixed die 22 and the movable die 32. The gate 52 and the cavity 53 are defined by the fixed die 22 and the movable die 32.

A hydraulic cylinder 40 is fixed to the diverter 33 via a bracket (not shown). A pressure rod 43 is connected to the piston rod 41 of the hydraulic cylinder 40 via a coupling 42. The pressure rod 43 is inserted into the through hole 34 formed in the diverter 33, and the tip 43A of the pressure rod 43 blocks the upper opening 34A of the through hole 34. The pressure rod 43 can be advanced and retreated in a direction approximately perpendicular to the mold opening direction of the die casting mold 10 by the operation of the hydraulic cylinder 40. When the hydraulic cylinder 40 is operated, it can advance from the retreated position shown in FIG. 1 into the second runner 50B and advance to the advanced position shown in FIG. 2. Therefore, in the die casting device 1 according to this embodiment, by advancing the pressure rod 43 into the second runner 50B, it is possible to pressurize the molten metal in the cavity 53 through the molten metal in the second runner 50B. The hydraulic cylinder 40, the piston rod 41 and the pressure rod 43 constitute the second pressure means according to the present invention.

The tip 43A of the pressure rod 43 is cylindrical. The second runner 50B has a corresponding shape portion 51 formed in a circular shape to correspond to the cross-sectional shape of the tip 43A of the pressure rod 43, and the circumferential gap between the surface 51A that defines the corresponding shape portion 51 and the tip 43A of the pressure rod 43 is set to, for example, a range of 0.5 to 3.0 mm. If the gap is less than 0.5 mm, the thin wall portion solidified in the gap will be cut off when the die-cast product is removed. If the gap exceeds 3.0 mm, the molten metal in the second runner 50B cannot be sufficiently prevented from flowing back through the gap when the molten metal in the second runner 50B is pressurized by the pressure rod 43, and a sufficient riser effect cannot be provided to the molten metal in the cavity 53. If the fluidity of the molten metal in the second runner 50B is good, backflow is likely to occur through the gap, so when pressurizing the molten metal in the second runner 50B with the pressure rod 43 before the filling of the molten metal into the cavity 53 is complete, it is preferable to set the gap between the surface 51A that defines the corresponding shape portion 51 of the second runner 50B and the tip 43A of the pressure rod 43 to 3.0 mm or less.

Above, the basic configuration of the die-casting device 1 according to this embodiment has been described. Next, the die-casting method that can be performed by the die-casting device 1 according to this embodiment will be described with reference to Figs. 3 to 7. Here, Fig. 3 is a graph for explaining the die-casting method that can be performed by the die-casting device according to this embodiment, showing the injection speed and the pressure rod stroke. Also, Fig. 4 is a diagram showing the state of the die-casting device at the location marked with (i) in Fig. 3, Fig. 5 is a diagram showing the state of the die-casting device at the location marked with (ii) in Fig. 3, Fig. 6 is a diagram showing the state of the die-casting device at the location marked with (iii) in Fig. 3, and Fig. 7 is a diagram showing the state of the die-casting device at the location marked with (iv) in Fig. 3.

In FIG. 3, the horizontal axis indicates time [s], the vertical axis on the left indicates the injection speed [m/s], which indicates the numerical value of the injection speed shown by the solid line, and the vertical axis on the right indicates the pressure rod stroke [mm], which indicates the numerical value of the pressure rod stroke shown by the dashed line.

In the die casting method according to this embodiment, first, the die casting mold 10 is clamped by moving the movable mold 30 in the direction of movement of the movable mold 30 indicated by A←→A' in FIG. 4, etc., and the runner 50, gate 52, and cavity 53 are defined inside the die casting mold 10 (the state shown in FIG. 4).

Next, the molten metal is supplied into the injection sleeve 23, and the plunger tip 25 is slid in the injection sleeve 23, so that the molten metal in the injection sleeve 23 is filled into the cavity 53 through the runner 50 and the gate 52. Furthermore, as shown by the symbol (ii) in Fig. 3, after the injection of the molten metal into the cavity 53 by the first pressurizing means (plunger tip 25, plunger rod 24, and injection cylinder (not shown)) is started, the die casting device 1 is operated so that the second pressurizing means (hydraulic cylinder 40, piston rod 41, and pressurizing rod 43) starts pressurizing the molten metal in the runner 50 before the injection speed of the molten metal drops completely (state of Fig. 5). That is, in this embodiment, as shown in the graph shown in Fig. 3, the first pressurizing means and the second pressurizing means are operated so that a line with a negative slope when the injection speed drops and a line with a positive slope when the pressurizing rod stroke increases cross each other. In performing such an operation, it is important that both pressurizing means operate for a short period of time in which solidification does not occur within the cavity 53. By preventing backflow of molten metal from the cavity 53 side to the injection sleeve 23 side, as shown by the arrow from the second runner 50B to the first runner 50A in Figure 5 , it is possible to effectively prevent problems such as high pressure not being generated in the cavity 53.

Furthermore, as shown by symbols (ii) to (iv) in FIG. 3, the pressurization speed of the molten metal in the runner 50 by the pressurizing rod 43 is set to include a first stage (from the point indicated by symbol (ii) to the point indicated by symbol (iii) in FIG. 3) in which high-speed pressurization is performed from when the pressurizing rod 43 starts pressurizing until high pressure is generated in the cavity 53 by blocking the flow path, and a second stage (from the point indicated by symbol (iii) to the point indicated by symbol (iv) in FIG. 3) in which low-speed pressurization is performed after the pressurizing rod 43 blocks the flow path and high pressure is generated in the cavity 53. In other words, in this embodiment, the second pressurizing means is operated so that, as shown in the graph diagram shown in FIG. 3, the first stage is composed of a line with a steep slope where the pressurizing rod stroke is high-speed pressurization, and a line with a gentle slope where the pressurizing rod stroke is low-speed pressurization.

The state of the portion indicated by the symbol (iii) in FIG. 3 is shown in FIG. 6. When switching between the first stage, in which the pressure rod stroke is high-speed pressurization, and the second stage, in which the pressure rod stroke is low-speed pressurization, the position of the tip 43A of the pressure rod 43 is the boundary position indicated by the symbol 50C, which is the boundary between the first runner 50A and the second runner 50B. When the tip 43A of the pressure rod 43 moves to the boundary position 50C, a high pressure is generated in the cavity 53 (the state in FIG. 6). In this state, the flow path is blocked by the pressure rod 43, so the operation of the injection cylinder of the plunger rod 24 may be turned off.

Furthermore, the pressurization speed of the second stage of low-speed pressurization, indicated by the reference symbol (iv) in Figure 3, is determined based on the amount of solidification shrinkage of the molten metal in the cavity 53, which is based on solidification analysis. By slowly advancing the pressurizing rod 43 toward the cavity 53 according to the amount of solidification shrinkage of the molten metal based on the pressurization speed of the second stage of low-speed pressurization, it is possible to perform the die casting method under optimal conditions (state in Figure 7).

Furthermore, in this embodiment, as shown in FIG. 3, when the time from the end of injection of the molten metal into the cavity 53 by the first pressurizing means to the end of the first stage of pressurizing the molten metal in the runner 50 by the second pressurizing means is T,
0s<T≦0.2s
The second pressurizing means is configured to operate so that the following inequality holds. In the die casting device 1 according to this embodiment, the rise time of the pressurizing pressure from the completion of filling of the molten metal by the plunger tip 25 to the generation of pressurization by the pressurizing rod 43 is set to be 0.1 s, and the second pressurizing means is configured to operate with the time T = 0.1 s as a target value. The operation of such a second pressurizing means may be controlled according to the performance of the hydraulic cylinder 40, etc. Incidentally, in this embodiment, the hydraulic cylinder 40 with a pressure performance of 80 MPa is used, and the operation delay time from the input of the operation start signal to the hydraulic cylinder 40 to the actual operation of the pressurizing rod 43 is 0.15 s, so that the operation start signal to the hydraulic cylinder 40 is input about 0.15 s before the start target of the first stage where the pressurizing rod stroke shown by the symbol (ii) in FIG. 3 becomes high-speed pressurization.

Then, when the molten metal in the cavity 53 solidifies, the movable die 30 is moved to open the die, and the pressure rod 43 is retracted, and the die-cast product is removed from the movable die 30. By performing the series of operations described above, a suitable feeder effect can be obtained, so that a die-casting device 1 capable of improving the quality of the die-cast product molded in the cavity 53 and a die-casting method using the die-casting device 1 can be provided. In particular, by performing the die-casting method shown in FIG. 3, a large clamping force to prevent the die-opening phenomenon caused by the molten metal pressure in the conventional die-casting method is not required. Therefore, a large product (cavity) can be cast with a casting machine with a small clamping force. Furthermore, since there is no need to further pressurize the molten metal by the first pressurizing means such as the plunger tip 25 after filling the cavity 53 with the molten metal, as in the conventional technology, it is possible to make the unnecessary part called the biscuit that inevitably remains in the die-cast product as thin as possible. Therefore, the die casting device 1 according to this embodiment can improve yields compared to conventional techniques, and can provide cost advantages.

The above describes a preferred embodiment of the present invention, but the technical scope of the present invention is not limited to the scope described in the above embodiment. Various modifications and improvements can be made to the above embodiment. It is clear from the claims that such modifications and improvements can also be included in the technical scope of the present invention.

1 Die casting device, 10 Die casting mold, 20 Fixed mold, 21 Fixed holder, 22 Fixed die, 23 Injection sleeve (sleeve), 24 Plunger rod (first pressure means), 25 Plunger tip (first pressure means), 30 Movable mold, 31 Movable holder, 32 Movable die, 33 Diverter, 34 Through hole, 34A Upper opening, 40 Hydraulic cylinder (second pressure means), 41 Piston rod (second pressure means), 42 Coupling, 43 Pressure rod (second pressure means), 43A Tip, 50 Runner, 50A First runner, 50B Second runner, 50C Boundary position, 51 Corresponding shape part, 51A Surface, 52 Gate, 53 Cavity, T Time, (ii) First stage, (iv) Second stage.

Claims (4)

A die casting mold defining a cavity and a runner communicating with the cavity;
A first pressurizing means for filling the molten metal into the cavity;
A second pressurizing means for pressurizing the molten metal in the runner;
The second pressure means includes a pressure rod that advances and retreats in a direction substantially perpendicular to a mold opening direction of the die casting mold,
the second pressurizing means starts pressurizing the molten metal in the runner before the injection speed of the molten metal reaches a complete drop after the first pressurizing means starts injection of the molten metal into the cavity;
A die casting apparatus characterized in that the first pressurizing means and the second pressurizing means are configured to operate for a short period of time that does not cause solidification of the molten metal in the cavity . A die casting mold defining a cavity and a runner communicating with the cavity;
A first pressurizing means for filling the molten metal into the cavity;
A second pressurizing means for pressurizing the molten metal in the runner;
The second pressure means includes a pressure rod that advances and retreats in a direction substantially perpendicular to a mold opening direction of the die casting mold,
the second pressurizing means starts pressurizing the molten metal in the runner before the injection speed of the molten metal reaches a complete drop after the first pressurizing means starts injection of the molten metal into the cavity;
A die casting device characterized in that the position of the tip of the pressure rod when the injection speed of the molten metal has reached its lowest point is configured to advance by 27% of the pressure rod stroke amount from when the pressure rod starts to apply pressure to when it blocks the flow path and high pressure is generated in the cavity . A die casting mold defining a cavity and a runner communicating with the cavity;
A first pressurizing means for filling the molten metal into the cavity;
A second pressurizing means for pressurizing the molten metal in the runner;
The second pressure means includes a pressure rod that advances and retreats in a direction substantially perpendicular to a mold opening direction of the die casting mold,
the second pressurizing means starts pressurizing the molten metal in the runner before the injection speed of the molten metal has completely decreased after the first pressurizing means starts injection of the molten metal into the cavity ; and
The first pressurizing means and the second pressurizing means are configured to operate for a short period of time such that solidification of the molten metal does not occur in the cavity,
A die casting device characterized in that the position of the tip of the pressure rod when the injection speed of the molten metal has reached its lowest point is configured to advance by 27% of the pressure rod stroke amount from when the pressure rod starts to apply pressure to when it blocks the flow path and high pressure is generated in the cavity . A die casting method characterized by performing die casting using the die casting device described in any one of claims 1 to 3.

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