JPH064250B2 - Mold clamping device using shape memory alloy - Google Patents

Description

TECHNICAL FIELD The present invention relates to a mold clamping device of a molding machine such as injection molding, compression molding, transfer molding and the like.

[Prior Art] As a method of driving a molding machine, three methods of air drive, hydraulic drive, and electric drive are generally used. However, in either method, when the material resin is injected and filled in the cavity of the mold, it is necessary to clamp the mold with a strong force so that the mold does not open, and to hold this force for a certain period of time. Most of the cost of the device goes to such means.

[Problems to be Solved by the Invention] Of the above-mentioned driving means, one using air as a driving source is
Air is supplied by a compressor, but its pressure is 5
In order to generate a large mold clamping force of 10 kg / cm ² , the cylinder inevitably has a large diameter, which causes problems such as an increase in production cost. In addition, since air has a high compressibility, it is difficult to control, and only a very small machine with a small mold clamping force can be put to practical use.

When electricity is used as the drive source, the conventional means are:
The output of the electric motor is converted into mechanical energy via ball screws and nuts, and is converted into output such as mold clamping force. However, in order to produce a large output, the electric motor and the ball screw become large in size and expensive, so that it is practically difficult to use for a large machine.

The hydraulic drive, which is most widely used, is easy to generate a large output, and is most often used from small size to large size because of its controllability and cost. Improvements such as imperfect mold clamping pressure, energy saving during operation, and reduction of production cost are required.

Compared with each of the current mold clamping methods, the present invention can significantly reduce the cost as the mold clamping means, and can reliably maintain the mold clamping force by its own force regardless of the external force, The purpose of the present invention is to provide a new mold clamping device that can significantly reduce operating energy.

[Means for Solving the Problems] One of the characteristics of the shape memory alloys known so far is that when it is deformed at a temperature lower than the deformation temperature, it exhibits a yielding phenomenon, and deformation strain remains after unloading. Is an apparent plastic deformation, and has the effect of recovering to a zero strain state by shape memory when the temperature is raised.

The present invention uses a shape memory alloy having such characteristics as a mold clamping member, and one of the inventions is a fixed plate and a movable plate that moves forward and backward with respect to the fixed plate by being guided by a tie bar. A mold provided separately on the opposing surface of the movable plate and the fixed plate, a device on the back of the movable plate that opens and closes the mold, and a locking device that fixes the movable plate in the mold closed state. And a shape memory alloy that generates a high pressure by a deforming force or a restoring force generated by a specific temperature is provided as a mold clamping member between the movable plate and the mold.

Another one is that the above-mentioned shape memory alloy is used for a locking device for restraining the mold opening / closing rod of the device to fix the movable plate, or a locking device for restraining and fixing the movable plate to the tie bar.

Furthermore, the present invention is directed to a pair of fixed plates, a movable plate located between the fixed plates and moving forward and backward with respect to one of the fixed plates by being guided by a tie bar, and the movable plate and the fixed plate facing each other. A mold clamping device comprising a mold provided separately on a surface, a device on the back of a movable plate that opens and closes the mold, and a locking device on the other fixed plate that fixes the movable plate in a mold closed state. It is also characterized in that the shape memory alloy is used as a mold clamping member and is provided between the other fixed platen and a locking device for restraining the mold opening / closing rod of the device.

[Operation] In the mold clamping device configured as described above, the movable platen is moved forward by the operation of the mold opening / closing device to close the mold, and then the movable platen is restrained by the lock device so that the movable platen does not move forward and backward by external pressure. When the mold clamping member made of shape memory alloy is heated or cooled, the mold clamping member acts to deform or recover to the original shape, and the mold clamping force due to the deformation force or recovery stress is generated there and the mold becomes strong. Tighten to.

Similarly, also in the lock device, the lock member acts so as to deform or recover the original shape by a specific temperature applied thereto, and the mold opening / closing rod or tie bar is tightened to fix the movable plate.

Hereinafter, the present invention will be described more specifically by taking a mold clamping device of an injection molding machine using hydraulic pressure as a drive source as an example.

[Embodiment] Embodiment 1 (FIG. 1) In the figure, reference numerals 1 and 2 are a pair of fixed plates which are arranged opposite to each other with a required space therebetween, and are connected by a plurality of tie bars 3 arranged at four corners. A movable platen 4 is movably inserted through the tie bars 3 and 3, and a mold 5 is separately attached to the facing surface between the movable platen 4 and the one fixed platen 1.

A die opening / closing device 6 using a hydraulic cylinder is attached to the outer center portion of the other fixed platen 2, and a die opening / closing rod 7 of the die opening / closing device penetrates a locking device 8 fitted in the central portion 2 of the fixed platen 2. Then, it is connected to the center of the back of the movable plate 4.

The lock device 8 is provided inside the lock member through a short tubular lock member 9 in a fixed plate surrounding the mold opening / closing rod 7, a guide bush 10 having seal rings before and after the lock member, and the guide bush 10. And a heating or cooling medium flow path 11.

Reference numeral 12 denotes a plate-shaped mold clamping member having a required area, which is disposed between the movable plate 4 and the mold 5, and is provided in a mold mounting plate 14 in which a flow path 13 for a heating or cooling medium is provided. The mold mounting plate 14 is housed with an operating space provided, and is fixed to the movable platen 4 by bolts called stepped reamer bolts.

The lock member 9 and the mold clamping member 12 are formed of a shape memory alloy that causes deformation or shape recovery under a specific temperature.

The locking member 9 is designed to have a large inner diameter at low temperature and a small inner diameter at high temperature. The locking member 9 is designed to have a size such that the mold opening / closing rod 7 can be tightened and restrained or loosened to smoothly move when the inner diameter changes. is there. Further, the outer diameter is designed so as to be in close contact with the fixed platen 2 and not to be separated regardless of the change of the inner diameter.

The mold clamping member 12 is composed of a plate body having at least an area equivalent to the projected area of the mold, which is bent to one side at a high temperature and subjected to a memory treatment so as to recover the original state at a low temperature.

Next, the operation will be described.

When the mold 5 is opened and closed, a medium (water or the like) whose temperature is lower than that of the temperature controller is used for the lock device 8 and the flow path 11 of the mold mounting plate 14.
To lower the temperature of the lock portion 9 and the mold clamping member 12. Due to this, the inner diameter of the lock portion 9 is formed large,
The clamping force for the mold opening / closing rod 7 is small. Further, the mold clamping member 12 is in a flat state, and the mold clamping force due to the deformation is not generated.

When pressure oil is fed to the mold opening / closing device 6 under such a state, the mold opening / closing rod 7 expands while being guided by the guide bush 10 because the hydraulic pressure is larger than the force for tightening the mold opening / closing rod 7. The movable platen 4 is moved forward with respect to the fixed platen 1 to close the mold 5.

After the mold is closed, when the temperature of the medium to the flow path 11 is raised and the temperature of the lock member 9 is raised, the inner diameter is deformed and the mold opening / closing rod 7 is deformed.
The mold opening / closing rod 7 is fixed to the fixed platen 2.

Next, when a temperature control medium of a predetermined high temperature is passed through the flow path 13 of the mold mounting plate 14 to raise the mold clamping member 12 to a temperature higher than the transformation temperature, the mold clamping member 12 is deformed into the shape memorized at that temperature. The force at that time acts strongly as a mold clamping force on the mold 5 to perform mold clamping.

This mold clamping is continued as long as the temperature of the mold clamping member 12 is maintained at a predetermined high temperature, during which the mold cavity can be filled with resin.

The mold opening after the completion of injection is performed by lowering the temperature of the lock member 9. When the lock member 9 has a predetermined low temperature due to the refrigerant flowing through the flow path 11, the inner diameter memorized at that temperature is restored to a large shape, and the clamping force of the mold opening / closing rod 7 is loosened.

After such an operation, the mold opening / closing device 6 is hydraulically operated, the mold opening / closing rod 7 is expanded / contracted, and the movable platen 4 is moved backward to open the mold 5.

In the process of opening the mold, when the coolant is passed through the flow path 13 of the mold mounting plate 14 and the temperature of the mold clamping member 12 is cooled to a predetermined low temperature, the mold clamping member 12 stores at that temperature. The original shape is restored.

Embodiment 2 (FIG. 2) In this embodiment, the locking device 8 in Embodiment 1 is
This is a case where the movable platen 4 is internally provided in the tie bar insertion portions 4a at the four corners of the movable platen 4 and the lock plate 9 tightens the tie bar 3 to fix the movable platen 4 to the tie bar 3.

Therefore, the other parts have the same configuration as that of the first embodiment, and the mold opening / closing and mold clamping actions are also the same, and the description thereof will be omitted to avoid duplication.

Embodiment 3 (FIGS. 3 and 4) In this embodiment, a locking device 15 by a known mechanical means for preventing the movable platen 4 from retreating and the other fixed platen 2 to which the mold opening / closing device 6 is attached. A plurality of plate-shaped mold clamping members 16 are provided in between, together with the mounting plate 17, and a recovery force or a deformation force generated by the mold clamping members 16 is applied to the movable platen 4 to strongly clamp the mold 5. It shows a case in which it is configured to perform.

The locking device 15, the mold clamping member 16 and the mounting plate 17 are
Each is circular and has a through hole 19 for receiving a plurality of pressure receiving rods 18 protruding from the back surface of the movable platen 4 when the mold is opened. In addition, there is an insertion hole in the center, and the insertion hole is used as the mold opening / closing rod 7
A mounting plate 17 is provided on the inside of the fixed plate 2 together with the mold clamping member 16, and a locking device 15 is further overlapped on the outside thereof and is pivotally attached to the fixed plate 2 by a stepped reamer bolt 20. A coil spring 21 for elastic pressure is provided between the lock device 15 and the bolt head.

The locking device 15 includes a seat plate 22 that is in contact with the mounting plate 17.
And a rotary plate 23 held by a frame edge provided on the outer periphery of the seat plate 22 and a hydraulically operated actuator 24 for rotating the rotary plate 23. The rotary plate 23 has the through hole 19 and A plurality of openings 19a are formed at the overlapping position. Also, the actuator 24, as shown in FIG.
It is swingably attached to the machine base 25.

In such a lock device 15, the actuator 24
The expansion / contraction motion of the piston rod 24a of the rotary plate 23
Rotates about the mold opening / closing rod 7 by a required angle, and when the rotation causes the opening 19a to overlap with the through hole 19, the pressure receiving rod 18 on the back surface of the movable plate is received in the through hole to open the mold. When the through hole 19 is closed due to the displacement of the opening 19a, the rotary plate 23 receives the end portion of the pressure receiving rod 18 and locks the rotary plate 4 in the mold closing position.

In the mold clamping by the mold clamping member 16 after the mold is closed, the heating medium having a predetermined temperature is passed through the flow path 13 of the mounting plate 17 to heat the mold clamping member 16 to the transformation temperature or higher, as in the above-described embodiment. . The mold clamping member 16 changes to a memorized shape at that temperature, and the force at that time acts on the movable platen 4 via the locking device 15 and the pressure receiving rod 18, and strongly clamps the mold clamping 5.

After completion of molding, first, a predetermined cooling medium is passed through the mounting plate 17 to cool the mold clamping member 16. Mold clamping member 16
Recovers to the memorized shape at that temperature, and the mold clamping force associated with the recovery is removed, and the force acting on the movable platen 4 from the lock device side disappears.
4 makes it possible to rotate in the opposite direction.

By rotating the rotary plate 23 in the opposite direction, the through hole 19 and the opening 19a are overlapped again and the pressure receiving rod 18 can be received. Then, when the mold opening / closing device 6 is hydraulically operated and the mold opening / closing rod 7 is expanded / contracted, the mold clamping plate 4 retracts to open the mold.

The mold thickness is adjusted by exchanging the pressure receiving rods 18 having different lengths.

In each of the above-mentioned embodiments, the mold opening / closing device 6 is composed of a hydraulic cylinder, but although omitted as an embodiment, an air cylinder, an electric motor and a ball screw / nut or the like can be used as the opening / closing device, and the mold clamping member 12, The temperature control of 16 may be performed directly or indirectly by using a heater or the like instead of passing water.

Furthermore, as the shape memory alloy, either one-way shape memory type or two-way shape memory type can be used.

[Effects of the Invention] Since the present invention uses the recovery stress or the deformation stress generated in the shape memory alloy as the mold clamping force of the mold as described above, it is necessary to perform the mold clamping by the conventional mechanical means. In a mold clamping device using hydraulic pressure as a drive source, a powerful mold clamping cylinder can be omitted. For this reason, the manufacturing cost can be greatly reduced, the energy can be saved, the space can be greatly improved, and the pressure can be completely maintained.The application of shape memory alloy as a mold clamping means is not limited to only small machines, but also to large machines. Since it can be applied, the economic effect is also great.

In addition, when the movable plate is locked by locking the tie bar with a lock member made of a shape memory alloy, the amount of extension of the tie bar during mold clamping can be reduced and the amount of recovery of the mold clamping member can be reduced compared to when the mold opening / closing rod is restricted. It also has the advantage of being small.

[Brief description of drawings]

The drawings show an embodiment of a mold clamping device using a shape memory alloy according to the present invention. FIG. 1 is a partial sectional view of the first embodiment, and FIG. 2 is a partial sectional view of the second embodiment. 3 is a partial sectional view of the third embodiment, and FIG. 4 is a sectional view taken along the line AA in FIG. 1 ... One fixed plate, 2 ... Other fixed plate 3 ... Tie bar, 4 ... Movable plate 5 ... Mold, 6 ... Mold opening / closing device 7 ... Mold opening / closing rod, 8 ... Lotk device 9 ...... Lock member, 11 ...... Flow path 12 ...... Clamping member, 13 ...... Flow path 14 ...... Mold mounting plate, 15 ...... Lock device 16 ...... Mold clamping member, 17 ...... Mounting plate 18 ...... Pressure receiving Rod, 19 ... Through hole 22 ... Seat plate, 23 ... Rotating plate 24 ... Actuator

Claims (4)

[Claims] 1. A fixed plate, a movable plate that moves forward and backward with respect to the fixed plate by being guided by a tie bar, a mold provided separately on the facing surface of the movable plate and the fixed plate, and a metal plate. It consists of a device at the back of the movable plate that opens and closes the mold, and a lock device that fixes the movable plate in the mold closed state, and a high pressure is generated between the movable plate and the mold by a deformation force or a recovery force generated by a specific temperature. A mold-clamping device using a shape-memory alloy, characterized in that a shape-memory alloy that generates a noise is provided as a mold-clamping member. 2. The shape memory alloy according to claim 1, wherein the lock device is made of a shape memory alloy for fixing the movable platen by restraining the mold opening / closing rod of the mold opening / closing device at a specific temperature. Mold clamping device. 3. The mold clamping device using a shape memory alloy according to claim 1, wherein the locking device is made of a shape memory alloy that fixes and fixes the movable plate to a tie bar at a specific temperature. 4. A pair of fixed plates, a movable plate which is located between the fixed plates and which moves forward and backward with respect to one of the fixed plates guided by a tie bar, the movable plate and the one fixed plate. A mold provided separately on the opposite surface of the movable plate, a device on the back of the movable plate that opens and closes the mold, and a locking device on the other fixed plate that fixes the movable plate in the mold closed state, Between the other fixed platen and the lock device for fixing the movable platen by restraining the mold opening / closing rod, a shape memory alloy that generates a high pressure by a deforming force or a restoring force generated by a specific temperature is provided as a mold clamping member. A mold clamping device using a shape memory alloy.