Mold opening and closing device

Abstract

To provide a mold opening and closing apparatus with simple maintenance, which can suppress a split nut and a male screw part from colliding with each other violently, and can suppress occurrence of shock.SOLUTION: A mold opening and closing apparatus 1 comprises: a fixed platen 4 that supports a fixed mold 2; a movable platen 5 that supports a movable mold 3; a plurality of tie bars 6 one end parts of which are connected to the fixed platen 4 and the other end parts of which are extended by inserting the movable platen 5; male screw parts 6a formed at the other end parts of the tie bars 6a; split nuts 7 to be detachably screwed into the male screw parts 6a; mold opening and closing cylinders 8 that are disposed on each tie bar 6, and which force the movable platen 5 to open and close by advancing and withdrawing the movable platen 5 to and from the fixed platen 4 by reaction force from the split nuts 7. In the mold opening and closing apparatus 1, at the mold opening time, mold opening control is executed such that a mold opening instruction to the mold opening and closing cylinders 8 disposed on some tie bars 6 in the plurality of tie bars 6 is quickly instructed to the mold opening instruction to the mold opening and closing cylinders 8 disposed on the remaining tie bars 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mold opening and closing device. [Background technology]

[0002] Conventionally, there has been known a mold opening and closing device that includes a fixed platen that supports a fixed mold, a movable platen that supports a movable mold, a plurality of tie bars each having one end connected to the fixed platen and the other end inserted through the movable platen, a male threaded portion formed on the other end of the tie bar, a split nut provided so as to be freely threadedly engaged with the male threaded portion, and a mold opening and closing cylinder provided on each tie bar that uses a reaction force from the split nut to move the movable platen forward and backward relative to the fixed platen to open and close the movable platen (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4254495 Summary of the Invention [Problem to be solved by the invention]

[0004] In the mold opening and closing device, when the mold is opened, a large impact may occur due to a collision between the male threaded portion and the split nut caused by backlash. In order to mitigate this impact and make it easier to open the mold, it is possible to apply grease containing molybdenum as a lubricant to the contact area between the fixed and movable molds.

[0005] However, when grease containing molybdenum is applied to the contact area between the fixed and movable dies, the grease can seep into the cavity, affecting product quality and increasing the cleaning load during maintenance.In addition, vibrations can affect the entire die casting machine, causing damage to equipment welds and loosening of wiring terminal screws, which can lead to unexpected machine troubles and problems that affect the machine's lifespan.

[0006] In view of the above, an object of the present invention is to provide a mold opening and closing device that is easy to maintain and can prevent violent collisions between the split nut and the male threaded portion, thereby suppressing the occurrence of impacts without requiring new capital investment. [Means for solving the problem]

[0007] [1] In order to achieve the above object, the present invention provides A fixed platen that supports the fixed mold, a movable platen that supports the movable mold, a plurality of tie bars each having one end connected to the fixed platen and the other end extending through the movable platen; A male thread portion formed on the other end of the tie bar; A split nut that is detachably screwed onto the male thread portion; a mold opening / closing cylinder provided for each of the tie bars, the mold opening / closing cylinder moving the movable platen forward and backward relative to the fixed platen by a reaction force from the split nut to open and close the movable platen; In a mold opening and closing device comprising: Among the plurality of tie bars, the tie bars that are subject to the difficulty of mold opening due to a specified cause are defined as "some tie bars", When opening the mold, The part of tie bars A mold opening command is sent to the mold opening / closing cylinder provided in , excluding some of the tie bars The present invention is characterized in that mold opening control is executed to issue an early mold opening command to the mold opening / closing cylinders provided on the remaining tie bars.

[0008] According to the present invention, by accelerating the mold opening instruction to the mold opening cylinders provided on some of the tie bars, it is possible to prevent the split nut from colliding violently with the male threaded portion, thereby suppressing the occurrence of impact. In addition, it is no longer necessary to apply grease as a lubricant to the contact portion between the fixed and movable dies, making maintenance easier.

[0009] [2] In addition, in the present invention, The mold opening and closing device is used in a die casting device, The stationary platen is provided with an injection device for supplying molten metal into the cavity, The part of the tie bars is The injection part of the tie bar Device It is preferable that the tie bar be the one closest to the first tie bar.

[0010] According to this configuration, by issuing a mold opening command for the mold opening cylinder attached to the tie bar on the injection device side, which is easily affected by thermal expansion, earlier than the other mold opening and closing cylinders, it is possible to open the parts that are difficult to open early, and it is possible to prevent the split nut and the male threaded portion from colliding violently, thereby suppressing the occurrence of impact. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is an explanatory diagram showing a mold closing state of the mold opening and closing device according to the embodiment of the invention. [Diagram 2] FIG. 4 is an explanatory diagram illustrating a mold opening and closing device according to the present embodiment in a mold open state. [Diagram 3] FIG. 13 is an explanatory diagram showing a schematic diagram of a state in which the split nut and the male thread portion of the diver are screwed together when the mold is closed in this embodiment. [Figure 4] FIG. 13 is an explanatory diagram illustrating a state in which the split nut and the male thread portion of the diver are screwed together when the mold is in an open state in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A mold opening and closing device according to an embodiment of the present invention will be described with reference to the drawings. With reference to Figs. 1 and 2, the mold opening and closing device 1 according to this embodiment includes a fixed mold 2, a movable mold 3 which is pressed against the fixed mold 2 to define a cavity 2a between the fixed mold 2 and the movable mold 3, a rectangular fixed platen 4 which supports the fixed mold 2, a rectangular movable platen 5 which supports the movable mold 3, four tie bars 6 each having one end connected to each of the four corners of the fixed platen 4, and an injection device 9 which is provided below the fixed mold 2 and which injects molten metal into the cavity 2a. Fig. 1 shows a schematic diagram of the mold opening and closing device 1 in a mold closed state, and Fig. 2 shows a schematic diagram of the mold opening and closing device 1 in a mold open state.

[0013] A die used in a die casting machine such as the die opening / closing device 1 of this embodiment uses a sliding core 3a to extract the shape of the product. A total of four sliding cores 3a are arranged in the movable die 3, one pair on the left and one pair on the right and one pair on the top and bottom, and each has a product shape surface to which the top, bottom, left and right shapes of the product are transferred. The sliding core 3a is subjected to a force that opens the movable die 3 in a direction that is 90 degrees different from the mold opening direction of the movable die 3 during casting. The fixed die 2 is provided with a backup part 2b that prevents the sliding core 3a from opening due to the pressure during casting. The casting pressure acts on the sliding core 3a in a direction that is 90 degrees different from the force that acts in the direction in which the movable die 3 is opened, and a force that tries to push the opposing sliding cores 3a apart acts. Therefore, the sliding core 3a and the backup part 2b of the fixed die 2 come into strong contact with each other, which may be one of the factors that prevent the movable die 3 from quickly leaving the fixed die 2 when the die is opened.

[0014] The injection unit 9 has a pressing function of pressing the casting (not shown) in the cavity 2a toward the movable mold 3 after the molten metal in the cavity 2a has solidified, that is, a function of assisting in mold opening. The injection unit 9 is generally provided below the fixed mold 2 to prevent air from remaining in the cavity 2a. Insertion holes 5a are provided at the four corners of the movable platen 5 in correspondence with the positions of the tie bars 6, through which the other ends of the tie bars 6 are inserted.

[0015] A male threaded portion 6a is provided at the other end of the tie bar 6 so as to be exposed to the outside from the movable platen 5 and to be located on the side farther away from the fixed platen 4 than the movable platen 5. A split nut 7 is provided to the male threaded portion 6a so as to be freely screwed.

[0016] The through hole 5a is provided with a mold opening / closing cylinder 8 formed in a cylindrical shape so that the tie bar 6 can be inserted therethrough. The mold opening / closing cylinder 8 includes a cylindrical cylinder body 8a and a piston 8b that can move forward and backward relative to the cylinder body 8a. The cylinder body 8a is provided with a mold closing side hydraulic chamber 8c to which hydraulic pressure is transmitted to cause the piston 8b to protrude relative to the cylinder body 8a, and a mold opening side hydraulic chamber 8c to which hydraulic pressure is transmitted to cause the piston 8b to retract relative to the cylinder body 8a. Hydraulic pressure is transmitted to the mold closing side hydraulic chamber 8c and the mold opening side hydraulic chamber 8c, and oil is discharged therefrom, via a hydraulic circuit 10.

[0017] The cylinder body 8a is fixed to the movable platen 5. The piston 8b is joined to the split nut 7.

[0018] Next, a description will be given of the mold opening and closing operation of the mold opening and closing device 1 of this embodiment. First, in the mold opening and closing device 1 of this embodiment, when opening the mold, the split nuts 7 are released from the tie bars 6, and the movable platen 5 and the movable mold 3 are moved by an electric motor (not shown) to a predetermined distance away from the fixed mold 2 and the fixed platen 4 so that the mold can be clamped by the mold opening and closing cylinder 8.

[0019] After the movable platen 5 and the movable die 3 are moved to a predetermined distance from the fixed die 2 and the fixed platen 4 by an electric motor (not shown), the split nut 7 is screwed onto the male thread 6a of the tie bar 6. Then, hydraulic pressure is transmitted to the die closing hydraulic chamber 8c, and the piston 8b and the cylinder body 8a receive a reaction force from the split nut 7, moving the movable platen 5 toward the fixed platen 4 side, and pressing the movable die 3 against the fixed die 2 with a pressure stronger than that of the electric motor (not shown). Then, the molten metal is poured from the injection device 9 into the cavity 2a. In high speed high pressure die casting (hereinafter, HPDC), the quality of the product is determined by the casting pressure. When the casting pressure is applied to the cavity 2a, it acts in a direction to push the fixed die 2 and the movable die 3 open, but in the sliding core 3a provided in the movable die 3, a force acts to firmly press the sliding core 3a against the backup part 2b of the fixed die 2. Then, once the molten metal in the cavity 2a has solidified, the oil in the mold closing side hydraulic chamber 8c is allowed to be discharged, while the injection device 9 presses the casting in the cavity 2a toward the movable mold 3, assisting in the mold opening of the movable mold 3 and the movable platen 5.

[0020] When the pressure in the mold opening / closing hydraulic chambers 8c and 8d is discharged, the movable mold 3 is separated from the fixed mold 2 by the injection unit 9 pressing the movable mold 3 side. However, in a situation where the sliding core 3a of the movable mold 3 is firmly pressed against the backup part 2b of the fixed mold 2, the movable mold 3 cannot be separated from the fixed mold 2. After that, hydraulic pressure is transmitted to the mold opening hydraulic chamber 8d to move the cylinder body 8a toward the split nut 7 relative to the piston 8b, thereby moving the movable mold 3 and the movable platen 5 in a direction away from the fixed mold 2 and the fixed platen 4 to open the mold. If the backup part 2b of the fixed mold 2 and the sliding core 3a of the movable mold 3 can be opened by the force of the injection unit 9 alone, the mold opening / closing cylinder 8 will not transmit the mold opening force even if it is operated, and the initial mold opening operation will be performed by the injection unit 9 alone.

[0021] When the mold cannot be opened by the force of the injection unit 9 alone, the mold opening and closing cylinder 8 operates to separate the movable mold 3 from the fixed mold 2 by a combined force with that of the injection unit 9. Because a gap equivalent to the backlash exists between the split nut 7 and the male thread portion 6a of the tie bar 6 in the moving direction of the movable platen 5, the split nut 7 located on the fixed platen 4 side of the male thread portion 6a by the backlash moves away from the fixed platen 4 by the backlash amount, transmitting the mold opening force to the movable platen 5. When the fixed mold 2 and the movable mold 3 including the sliding core 3a are separated by the combined force of the injection unit 9 and the mold opening and closing cylinder 8, the movable platen 5 becomes free and runs freely through the backlash of the split nut due to the pressure of the injection unit 9, so that the split nut 7 and the male thread portion 6a come into contact with each other again. Fig. 3 is an enlarged cross-sectional view showing the state in which the female thread portion 7a of the split nut 7 and the male thread portion 6a of the diver 6 are screwed together in a mold closed state, and Fig. 4 is an enlarged cross-sectional view showing the state in which the female thread portion 7a of the split nut 7 and the male thread portion 6a of the diver 6 are screwed together in a mold open state. If the impact when the split nut 7 and the male thread portion 6a move from the state shown in Fig. 3 to the state shown in Fig. 4 and come into contact again is too strong, there is a risk of problems occurring with the mold opening and closing device 1, such as a decrease in durability.

[0022] In this embodiment, an experiment was conducted to check whether a strong impact would occur while measuring the distance between the fixed platen 4 and the movable platen 5 at three locations in total, two above the mold opening and closing device 1 and one below, using a distance measuring device (not shown) and an accelerometer (not shown) for measuring impact. As a result, it was found that a strong impact occurs when the fixed platen 4 and the movable platen 5 are separated relatively smoothly on the upper side, whereas the fixed platen 4 and the movable platen 5 are not separated as smoothly on the lower side as on the upper side. This is presumably because, in the mold opening and closing device 1 of this embodiment, the injection unit 9 is disposed below the fixed mold 2, the lower part of the mold opening and closing device 1 is deformed by thermal expansion, and the relative separation between the fixed mold 2 and the movable mold 3 is not performed smoothly on the lower part, so that the movable platen 5 is tilted and cannot move smoothly, and the movable platen 5 moves suddenly after the pressure of the injection unit 9 and the mold opening and closing cylinder 8 increases.

[0023] Then, in order to make the distances between the fixed platen 4 and the movable platen 5 at a total of three locations, two at the top and one at the bottom, the same or substantially the same, the timing of transmitting hydraulic pressure to the mold opening side hydraulic chambers 8d of the mold opening / closing cylinders 8 located on the two lower tie bars 6 was advanced relative to the two upper tie bars 6, thereby successfully suppressing the occurrence of strong impacts.

[0024] In this embodiment, the two lower mold opening and closing cylinders 8 are controlled to transmit hydraulic pressure to the mold opening side hydraulic chamber 8d 0.4 seconds earlier than the two upper mold opening and closing cylinders 8, which successfully prevented the occurrence of strong impacts. However, since how early the hydraulic pressure is transmitted specifically depends on the operating speed and backlash of the mold opening and closing cylinders 8, it is desirable to verify the timing at which the occurrence of impacts can be prevented for each mold opening and closing device 1.

[0025] According to the mold opening and closing device 1 of this embodiment, by issuing the mold opening command to the mold opening and closing cylinders 8 respectively provided on the two lower tie bars 6 earlier than the mold opening command to the mold opening and closing cylinders 8 respectively provided on the two upper tie bars 6, it is possible to prevent the split nut and the male threaded portion from colliding violently with each other, thereby suppressing the occurrence of impact.

[0026] In addition, since the impact can be suppressed, there is no longer any need to apply molybdenum-containing grease to the fixed die 2 and the movable die 3 including the sliding core 3a. This also eliminates the problem of the fixed die 2 and the movable die 3 becoming dirty due to the grease applied to the sliding core 3a seeping into the cavity 2a, making maintenance easier.

[0027] In this embodiment, the mold opening control is performed to issue a mold opening command to the two lower mold opening / closing cylinders 8 earlier than the two upper mold opening / closing cylinders 8, but the mold opening control of the mold opening / closing device of the invention is not limited to this. For example, if it is found from the result of measuring the distance between the fixed platen and the movable platen that it is difficult to open the upper part of the fixed mold 2 and the movable mold 3 due to the structural reasons of the mold, the mold opening control may be performed so that the mold opening command of the mold opening / closing cylinder located at the upper part is earlier than the mold opening command of the mold opening / closing cylinder located at the lower part. The same may be performed for the left and right sides. In addition, it is important to keep the length of the time lag to the shortest time at which the impact is eliminated by testing from a short time from the same time. Although the mold opening is basically performed in parallel and at the same time, since it is a measure to firmly press the fixed mold 2 and the movable mold 3 including the sliding core 2a, a time lag longer than necessary will induce troubles in the mold and HPDC machine.

[0028] In addition, in this embodiment, the mold opening and closing device 1 having four tie bars 6 has been described, but the number of tie bars in the mold opening and closing device of the invention is not limited to four, and may be any number. For example, the number of tie bars in the mold opening and closing device of the invention may be three or five or more. Furthermore, as a method for eliminating or mitigating the mold opening shock, there is a method of slowing down the pushing speed of the movable mold 3 of the injection device 9 or reducing the pressure to mitigate the shock, but this method does not eliminate the strong imbalance in the pressure bonding between the fixed mold 2 and the movable mold 3 including the sliding core 3a even if the shock is mitigated, and does not fundamentally solve the problem of impeding the durability of the mold opening and closing device 1. [Explanation of symbols]

[0029] 1 Type opening and closing device 2 Fixed type 2a Cavity 2b Backup Division 3 Movable type 3a Sliding core 4 Fixed Platen 5 Movable platen 5a Insertion hole 6 Tie bar 6a Male thread 7 Split Nut 7a Female thread 8 Mold opening and closing cylinder 8a Cylinder body 8b Piston 8c Hydraulic chamber on mold closing side 8d Mold opening side hydraulic chamber 9 Injection device 10 Hydraulic circuit

Claims

1. A fixed platen that supports the fixed mold, a movable platen that supports the movable mold, a plurality of tie bars each having one end connected to the fixed platen and the other end extending through the movable platen; A male thread portion formed on the other end of the tie bar; A split nut that is detachably screwed onto the male thread portion; a mold opening / closing cylinder provided for each of the tie bars, the mold opening / closing cylinder moving the movable platen forward and backward relative to the fixed platen by a reaction force from the split nut to open and close the movable platen; In a mold opening and closing device comprising: Among the plurality of tie bars, the tie bars that are subject to the difficulty of mold opening due to a specified cause are defined as "some tie bars", A mold opening and closing device characterized in that, during mold opening, mold opening control is executed to issue a mold opening command to the mold opening and closing cylinders provided on some of the tie bars earlier than the mold opening commands to the mold opening and closing cylinders provided on the remaining tie bars excluding the some of the tie bars.

2. The mold opening and closing device is used in a die casting device, The stationary platen is provided with an injection device for supplying molten metal into the cavity, The part of the tie bars is 2. The mold opening and closing device according to claim 1, wherein the tie bars are located closer to the injection unit.

Images