JP2943964B2 - Mold clamping method in injection molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping method in an injection molding machine for clamping a movable mold and a fixed mold provided in an injection molding machine such as an injection molding machine and a die casting machine by pressing the molds together. Things.

[0002]

2. Description of the Related Art Injection molding machines such as an injection molding machine and a die casting machine are classified into a vertical mold and a horizontal mold according to their mold clamping directions, and a vertical injection mold and a horizontal mold according to the material injection direction. Among them, for example, an injection molding apparatus of a horizontal clamping horizontal injection type is generally configured as follows. That is, the cylinder platen is supported and fixed at the four corners by tie rods at a position facing the fixed platen, whose mold mounting surface is set upright on the machine base with the sideways.

[0003] A movable platen is provided between the fixed platen and the cylinder platen with four corner holes slidably fitted to tie rods. The movable platen has a central portion of the cylinder platen. The working end of the main ram which moves forward and backward by hydraulic pressure in the ram hole provided in the ram hole is fixed.
And, on the opposing surface of the fixed platen and the movable platen,
A fixed mold and a movable mold whose planes face each other are mounted respectively. Further, an injection unit for injecting the molten metal or plasticizing and injecting the resin is attached to the fixed platen side, and this injection unit is detachably joined to, for example, a fixed sleeve on the fixed platen side.
The inner hole of the fixed sleeve is communicated with the cavity of the mold via the runner of the fixed mold.

[0004] With this configuration, when the main ram advances hydraulically, the movable platen integrated therewith moves with the movable mold and is clamped to the fixed mold. Therefore, the injection unit is joined to the fixed sleeve of the fixed platen, and the molten metal or resin is injected into the cavity of the mold. After the molten metal or resin in the cavity has solidified, the piston rod of the mold closing cylinder is retracted, and the movable mold is retracted, the mold is opened, and the product is taken out, completing one injection cycle. I do.

[0005]

However, in such a conventional mold clamping apparatus for injection molding, when the movable platen is moved by the mold clamping cylinder to clamp the mold, it is driven because the stroke of the mold clamping cylinder is large. Therefore, the position control and responsiveness of the mold clamping cylinder are low. Further, the locking state of the movable platen during mold clamping was unstable. Furthermore, since the movable platen holding the movable mold and the fixed platen holding the fixed mold are pushed more strongly at the center than at the four peripheral portions, the movable platen and the fixed platen are rotated four times around the central portion. It will bend so as to be separated more than the part. In particular, the fixed platen on which the fixed mold having a lower rigidity than the movable mold is mounted will bend more than the movable platen.
In the case of a large injection molding device such as 4000 tons,
It becomes 1-2 mm at the center of the upper surface of the fixed platen.

As a result, the fixed mold is also curved, and the shape of the mold cavity is changed so that a molded product having an accurate shape and size cannot be obtained. In addition, the injection material is formed from the mating surface of the fixed mold and the movable mold. Will erupt. In particular, if small foreign matter adheres or is scratched near the outer periphery of the mating surface of the mold, the injection material leaks vigorously from the gap of the mold, which is dangerous. There is a problem that bleeding must be removed and the work efficiency after product removal is reduced.

Further, in the above-mentioned conventional mold clamping device,
Since the mold clamping cylinder is provided on the movable platen side so as to protrude from the movable platen in the axial direction, a dedicated space for the mold clamping cylinder is required, and the installation space of the entire injection molding apparatus is increased. The present invention has been made in view of the above points, and provides an injection-molding mold clamping device capable of reducing the curvature of a mold during mold clamping and reducing the installation space of the entire device. It is intended to be.

[0008]

In order to achieve the above object, the present invention uses a mold clamping device of an injection molding apparatus having a fixed plate provided with a mold clamping cylinder and a movable plate provided with a moving device. The movable platen is moved in the direction of the fixed platen, and the mold is clamped with a relatively small force so that the clearance between the surfaces of the clamping force acting is substantially zero, and the relative movement between the movable platen and the fixed platen is locked. The cylinder is operated to clamp the mold with a predetermined force.

In addition, a ball screw is used for the tie bar, a ball screw nut is provided for the movable platen, and the ball screw nut is rotated to move the movable platen. Lock the rotation.
Furthermore, the number of mold clamping cylinders provided on the fixed plate is provided at one location near the center, and a hole through which the injection cylinder can penetrate is provided at the center of the mold clamping cylinder so that injection can be performed from the through hole. .

Further, a pressurizing cylinder is provided as a hydraulic drive method of the fixed platen cylinder, a displacement gauge is attached to the pressurized cylinder, and the stroke of the pressurized cylinder detected by the displacement meter is controlled, whereby the fixed platen cylinder is driven. Hydraulic control was performed. Furthermore, the hydraulic path between the fixed platen cylinder and the pressurizing cylinder is separated and independent from the hydraulic path of the molding machine body, and a medium with low compressibility is used as the hydraulic medium between the fixed platen cylinder and the pressurizing cylinder. Furthermore, a mold mounting plate is superimposed on and supported by the fixed plate, and a cylinder hole opened to the mold mounting plate is provided in the fixed plate. The ram was formed as a hollow body, and the liquid surface acting surface was provided in two directions, an axial direction and a radial direction.

[0011]

[Function] The movable platen to which the movable mold is fixed is moved by rotating the ball screw nut, and after the movable mold and the fixed mold are matched, the rotation of the nut is locked and movable. After the mold is fixed, oil is fed to the cylinder hole of the movable platen, and the ram moves in the cylinder hole.
The mold mounting plate integrated with the ram moves to perform mold clamping. At the time of this mold clamping, the sliding amount of the ram and the mold clamping force are accurately adjusted by controlling the stroke of the pressurizing cylinder.
Furthermore, coupled with the fact that the movable mold is firmly fixed with the lock of the ball screw nut, the ram is pressed by the hydraulic pressure in the cylinder hole as a unit with the mold mounting plate. After that, even if the injection material is subsequently injected into the mold cavity, the injection material does not erupt from the mold mating surface to form burrs.

[0012]

This embodiment shows an example in which the present invention is applied to an injection molding apparatus of a horizontal clamping horizontal injection type. FIG. 1 is a front view showing an embodiment of an apparatus for carrying out the method of the present invention, FIG. 2 is a side view as viewed from A in FIG. 1, FIG. 3 is a sectional view of a mold clamping cylinder portion, and FIG. FIG. 5 is a structural view of a ball screw nut portion,
FIG. 6 is a configuration diagram of the mold clamping cylinder.

In FIG. 1 and FIG. 5, four corners of a fixed platen 2 having a base fixed to a machine base 1 are provided at four corners.
One end of the tie rod 3 is inserted, and an end face of the tie rod 3 and a part of the fixed platen 2 are fixed to each other by a holding plate 6 and a bolt 7 fixed to the tip of the tie rod 3 via a ring 4 and a span ring 5. Thus, the rotation of the tie rod 3 is restricted and the tie rod 3 is firmly fixed to the fixed platen 2. On the other hand, machine base 1
At the end on the side opposite to the fixed platen 2, there is provided a connecting plate 8 formed in a substantially square frame shape, and the leg 8 a is slidably fitted to a plate-like rail 1 a provided on the machine base 1. The fixed platen 2 is provided at the four corners of the frame of the connecting plate 8.
The other end of each of the four tie rods 3 extending in the horizontal direction is inserted through the spanning ring 9, whereby the rotation of the tie rod 3 is restricted and the connecting plate 8 is connected.
It is constituted so that it may be fixed firmly.

Reference numeral 10 denotes a movable platen which is located between the fixed platen 2 and the connecting plate 8 and whose vertical plane is opposed to the vertical plane of the fixed platen 2 and which is erected.
A horizontal member 10a is integrally formed at the lower end thereof, and a guide shoe 11 slidably mounted on the rail 1a is bolted below the horizontal member 10a. By doing so, the movable platen 10 is formed integrally with the guide shoe 11 so as to be able to advance and retreat in the direction toward and away from the fixed platen 2, and the horizontal member 10
The height of the movable platen 10 is finely adjusted by the action of the inclined surfaces 10b, 11b provided on the movable platen 10 and the guide shoe 11 by adjusting the horizontal bolt 9 for fixing the guide plate 11 to the guide plate 11. Is configured.

Further, as shown in FIG. 5, each of the four tie rods 3 has a concave hole 10c formed at each of four corners of the movable platen 10.
A ball screw nut 12 formed in a cylindrical shape is provided between the concave hole 10c and the tie rod 3.
It is formed so as to be rotatable and movable in the axial direction via a needle bearing 13 and is interposed. Tie rod 3
A substantially half of the movable platen 10 side is provided with a screw groove 3b having a semicircular cross section. In this screw groove 3b, a plurality of balls 14 held in hemispherical concave holes of the ball screw nut 12 are provided. Rollably engaged. By doing so, the ball screw nut 1 can be used in the drive described below.
When the rotating plate 2 is rotated, the movable platen 10 advances and retreats along the tie rod 3 by a screw action.

The inner wall surface 13 of the mounting member 13a of the needle bearing 13 which is integrally fixed to the movable platen 10 at the inner end face in the mold matching direction in the concave hole 10c.
b and tip end 1 of ball screw nut 12 on the mold-matching direction side
A gap of, for example, about 0.5 mm is provided between the ball screw 2a and the ball screw 2a so that the ball screw nut 12 can be easily rotated.

Therefore, a rotation driving device for the ball screw nut 12 will be described. In FIGS. 4 and 5, a substantially square frame-shaped bearing plate 17 having an upright edge is bolted to the vertical end face of the movable platen 10 on the connecting plate 8 side. One end of the nut 12 is rotatably supported by a bearing 18 fitted in a bearing hole of the bearing plate 17. 19 is a bearing retainer for fixing the bearing 18 by being bolted to the bearing plate 17.
Reference numeral 20 denotes a seal member for preventing the oil put in the oil reservoir 21 from leaking.

On the end face of each of the ball screw nuts 12,
The driving rotators 22, 23, 24, 25 are respectively fixed through the center holes through the respective tie rods 3, and a driving rotator 27 having an electromagnetic brake 26 is provided between the upper driving rotators 22, 23. Is fixedly provided on a shaft 28 rotatably supported by the bearing plate 17. A tuning rotor 31 is provided between the driving rotors 22, 23 and 27.

Further, between the lower driving rotators 24 and 25, a driving rotator 32 is rotatably supported by the bearing plate 17, and the driving rotator 32 is connected via a shaft (not shown). A motor 33 is integrally pivoted to rotate each ball nut. Here, when the ball screw nut 12 is rotated by the motor 33 or the like, the tuning rotating body 31 and the driving rotating bodies 22, 23, 24, and 25 rotate simultaneously, so that the movable platen 10 moves smoothly. When the electromagnetic brake 26 is operated to stop the rotation of the four ball screw nuts 12, the movable platen is configured to be locked.

A movable mold 15 is removably mounted on the vertical plane of the movable platen 10 having the above-described structure, and a mold mounting plate 45 (to be described later) supported on the fixed platen 2 by being overlapped therewith. In the vertical plane, the fixed mold 16
Are detachably attached. By doing this,
When the movable platen 10 is advanced and retracted along the tie rod 3, the movable mold 15 is configured to be matched with the fixed mold 16 or opened.

The movable platen 10 is moved forward and backward by rotating the ball screw nut 12.
It is also possible to attach a moving cylinder (not shown) to the movable platen 10 and use the movable cylinder to move the movable platen 10 forward and backward. In this case, the drive of the ball screw nut 12 is kept free. In this manner, the movable platen 10 is advanced, and the movable mold 15 and the fixed mold 16 are moved.
After the mold is matched, the ball screw nut 12 is locked, so that a slight gap provided between the movable platen 10 and the movable platen 10 is eliminated, and the bearing plate 17 is pressed against the movable platen 10.

In the present apparatus, as shown in detail in FIG. 3, a mold clamping cylinder is provided on the fixed platen 2 side. That is, on the vertical plane of the fixed platen 2,
A square plate-shaped mold mounting plate 45 in which the rod holes at the four corners are slidably fitted to the tie rods 3 is superimposed, and the surface of the fixed platen 2 facing the mold mounting plate 45 is near the center. 1 in
A cylinder hole 46 provided with a hole through which the injection cylinder can penetrate is provided at a position and at the center of the cylinder hole 46, and is provided to open to the mold mounting plate 45 side.

On the mold mounting plate 45 side, a liquid surface acting surface which is slidably fitted in the cylinder hole 46 is provided in two axial and radial directions.
A hollow ram 47 provided so as to act in the direction is integrally fixed by bolts 48, and the fixed platen 2 and the mold mounting plate 45 pass through bolt holes of the fixed platen 2. It is fixed by a bolt 50 screwed into a screw hole of the mold mounting plate 45. A spring 51 is loaded between the head of the bolt 50 and the bottom of the spring hole provided in the fixed platen 2 in a direction to move the mold mounting plate 45 toward the fixed platen 2. The same effect can be obtained by using the spring 51 as a hydraulic cylinder.

On the peripheral surface of the ram 47, a packing 52 is provided.
The bottom surface of the cylinder hole 46 is communicated with a hydraulic pressure source through an oil passage (not shown). When oil is supplied to the rear side of the cylinder hole 46, the mold mounting plate 47 It is configured to move against the resiliency of 51 and perform mold clamping.

In FIG. 2, reference numeral 53 denotes an injection cylinder mounted on the outer flat surface of the fixed platen 2, which is provided with a plunger tip which moves in and out of an injection sleeve (not shown) by hydraulic pressure, and is supplied into the injection sleeve. By pushing the molten metal with the plunger tip moving forward, the mold 15,
It is configured such that the molten metal is injected into the cavity formed in 16. In FIG. 2, what is indicated by a dotted line 54 is an injection sleeve mounting hole provided in the fixed platen 2, and 53a is a mounting portion of an injection cylinder mounting frame.

Further, as shown in FIG. 6, a pressure cylinder 55 is connected to the ram 47 as a hydraulic pressure supply source.
The stroke displacement amount of the pressurizing cylinder 55 detected in 6 is converted by the arithmetic processing control device 57 into the advance amount of the ram 47 and the pressing force. Here, feedback control is performed on the electromagnetic valve 58 and the hydraulic unit 59 by comparing the advance amount and the pressing force of the ram 47 set in advance, and the stroke amount of the pressurizing cylinder 55 is corrected. It is also possible to detect and control the hydraulic pressure of the ram 47.

The operation of the injection molding apparatus configured as described above will be described. The movable platen 10 is moved forward by rotating the ball screw nut 12 from the mold open state shown in FIG. 1, and after the movable mold 15 and the fixed mold 16 are matched, the ball screw nut 12 is locked and the movable metal The mold 15 is firmly fixed. After matching the molds in this manner, the mold mounting plate 4
When oil is press-fitted between the end surface of the ram 47 provided on the cylinder 5 and the bottom surface of the cylinder hole 46, the ram 47 and the fixed platen 2 integrated therewith resist the elastic force of the spring 51 and accompany the fixed mold 16. It moves slightly and mold clamping is performed. At the time of this mold clamping, the movable platen 10 is firmly braked because the mold mounting plate 45 is pressed at the center by the mold clamping cylinder composed of the cylinder hole 46 and the ram 47 by the movement of the ram 47. As a result, the movable mold 15 and the fixed mold 16 do not bend, and there is no gap in the joint surface between the movable mold 15 and the fixed mold 16.

Here, the driving of the ram 47 is performed by the connected pressure cylinder 55. Since the cylinder diameter of the pressure cylinder 55 is designed to be smaller than the diameter of the ram 47,
By driving the pressure cylinder 55 with a small oil pressure, a force generated by the ram 47, that is, a large mold clamping force is obtained. Further, by controlling the stroke displacement amount of the pressurizing cylinder 55, the sliding amount of the ram 47 and the mold clamping force can be accurately controlled. In particular, by adjusting the stroke amount of the pressurizing cylinder 55 in accordance with the maximum sliding amount of the ram 47, a stopper for preventing the ram 47 from coming off the cylinder hole 46 becomes unnecessary.

Furthermore, since the movable mold 15 is firmly fixed by locking the ball screw nut 12, the stroke of the mold clamping cylinder including the ram 47 and the cylinder hole 46 can be set to an extremely small value. The amount of oil in the mold clamping cylinder can be reduced, and therefore the hydraulic response is improved. This effect can be further improved by using a medium having extremely low compressibility as the hydraulic medium between the mold clamping cylinder and the pressurizing cylinder.

After clamping in this manner, an injection material such as molten metal or resin is injected into the mold. At the time of this injection, there is no gap between the joint surfaces of the movable mold 15 and the fixed mold 16 as described above, and even if the injection material is injected into the cavity, the joint surface of the molds 15 and 16 is not changed. Since the injection material does not erupt from the
Molded products with accurate shapes and dimensions can be obtained reliably and easily.
After the injection material injected into the mold cavity is solidified, the oil in the pressurizing cylinder 55 is drained through the electromagnetic valve 58, and the ram 47 retreats due to the elastic force of the spring 51, and the oil in the cylinder hole 46 is removed. Releases naturally and releases mold clamping. Further, the movable platen 10 is moved to take out the product, and the molding cycle is completed.

If the mold clamping force and firing force are known,
Since the deformation dimension of the fixed mold 16 and the center of the axis of the fixed platen 2 can be known in advance by calculation or experiment, the advance amount and pressure of the ram 47 can be determined in advance according to the values. Of course, the amount of deformation of the surface of the fixed mold 16 is detected by using, for example, an ultrasonic wave, a photoelectric tube, a piezoelectric element, or the like, and the amount of advance of the ram 47 is controlled in accordance with the detected amount. It is also possible to prevent deformation.

In this embodiment, the cylinder hole 4
The number of the mold clamping cylinders composed of 6 and the ram 47 is not limited, and a plurality of mold clamping cylinders may be provided. In this embodiment, an example in which the present invention is applied to an injection molding apparatus of a horizontal clamping horizontal injection type is shown, but the same effects can be obtained without limiting the clamping direction and the injection direction.

[0033]

As is apparent from the above description, according to the present invention, in the mold clamping method in the injection molding apparatus,
Using a mold clamping device of an injection molding machine having a fixed plate provided with a mold clamping cylinder and a movable plate provided with a moving device, the movable plate is moved in the direction of the fixed plate and the mold is clamped with a relatively small force. Since the gap between the force acting surfaces is substantially zero, and the relative movement between the movable platen and the fixed platen is locked, the mold clamping cylinder is operated to clamp the mold with a predetermined force. A ball screw is used for the tie bar, a ball screw nut is provided for the movable platen, and the ball screw nut is rotated for moving the movable platen. The rotation of the nut is locked when the relative movement between the movable platen and the fixed platen is locked. Further, the number of cylinders provided on the fixed plate is provided at one location near the center, and a hole through which the injection cylinder can penetrate is provided at the center of the mold clamping cylinder so that injection can be performed from the through hole. , Mold clamping cylinder installed on fixed plate A pressure cylinder is provided as a hydraulic drive method, a displacement gauge is attached to this pressure cylinder, and the stroke of the pressure cylinder detected by this displacement meter is controlled to control the hydraulic pressure of the mold clamping cylinder provided on the fixed platen. In addition, the hydraulic path between the fixed platen cylinder and the pressurized cylinder is made independent of the hydraulic path of the molding machine body, and a medium with low compressibility is used as the hydraulic medium between the fixed platen cylinder and the pressurized cylinder. Furthermore, a mold mounting plate is superimposed on and supported by the fixed plate, and a cylinder hole opened to the mold mounting plate is provided in the fixed plate. Since the ram is a hollow body and the liquid surface action surface is provided in two directions, axial and radial, the pressure and amount of pressure required for mold clamping are accurate and responsive. Control well It has become possible. In particular, because the movable platen is moved and locked by using a ball screw nut, the mold clamping cylinder can be made compact, so that the amount of oil required for mold clamping can be minimized, and hydraulic pressure loss is maximally eliminated. did it.

Further, even if a force to bend the platen due to the mold clamping force acts on the platen, the center of the rear surface of the mold can be pressed so as not to bend. Can be obtained reliably and easily. In addition, since the molten material does not leak from between the molds during injection, safety is improved, and burrs due to solidification of the leaked molten material are not generated, and the quality of the product is improved. Furthermore, since no deburring operation is required, the preparation time is shortened and the operation rate of the machine is improved. Furthermore,
Since the mold clamping cylinder is embedded in the fixed platen, the whole device can be made smaller and more compact than the conventional one that is provided to protrude outside from the movable platen, and the installation space can be reduced. Can be.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a side view as viewed from A in FIG. 1;

FIG. 3 is a sectional view of a mold clamping cylinder part.

FIG. 4 is a side view as viewed from B in FIG. 1;

FIG. 5 is a structural view of a ball screw nut part.

FIG. 6 is a configuration diagram of a mold clamping cylinder.

[Explanation of symbols]

 2 Fixed platen 3 Tie rod 8 Connecting plate 10 Movable platen 12 Ball screw nut 15 Movable mold 16 Fixed mold 26 Electromagnetic brake 33 Motor 45 Mold mounting plate 46 Cylinder hole 47 Ram 50 Injection cylinder 55 Pressure cylinder 56 Displacement gauge 57 Calculation Processing control device 58 Solenoid valve 59 Hydraulic unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-219026 (JP, A) JP-A-60-137625 (JP, A) JP-A-61-215030 (JP, A) JP-A-3-3 121816 (JP, A) Fully open 60-191416 (JP, U) Fully open 63-93119 (JP, U) Fully open 2-99616 (JP, U) Fully open, 3-52118 (JP, U) (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 45/64-45/68 B29C 45/76 B22D 17/26

Claims (7)

(57) [Claims] 1. A movable platen is moved in the direction of a fixed platen by using a mold clamping device of an injection molding apparatus having a fixed platen provided with a mold clamping cylinder and a movable platen provided with a moving device, and a die is pressed with a relatively small force. It is characterized in that the mold is clamped with a predetermined force by operating the mold clamping cylinder after locking the relative movement between the movable platen and the fixed platen by locking the gap between the working surfaces of the mold clamping force to substantially zero. Mold clamping method in an injection molding apparatus. 2. A ball screw is provided on a tie bar, a ball screw nut is provided on a movable platen, and the ball screw nut is rotated to move the movable platen. The method according to claim 1, wherein the rotation is locked. 3. The number of mold clamping cylinders provided on the fixed plate is provided at one location near the center, and a hole through which an injection cylinder can penetrate is provided at the center of the mold clamping cylinder, and injection is performed from the through hole. 2. The method according to claim 1, wherein the mold is clamped. 4. A mold clamping method in an injection molding apparatus according to claim 1, wherein a pressurizing cylinder is provided as a hydraulic driving method of the mold clamping cylinder provided on the fixed board. 5. A hydraulic pressure control of a mold clamping cylinder provided on a fixed platen by mounting a displacement meter on a pressure cylinder and controlling a stroke of the pressure cylinder detected by the displacement meter. A mold clamping method in the injection molding apparatus according to claim 1. 6. The hydraulic path between the fixed platen cylinder and the pressurizing cylinder is independent of the hydraulic path of the molding machine body.
2. The method according to claim 1, wherein an incompressible medium is used as a hydraulic medium between the fixed platen cylinder and the pressurizing cylinder. 7. A mold mounting plate is superimposed on and supported by a fixed plate, and a cylinder hole opened to the mold mounting plate side is provided in the fixed plate, and a ram slidably fitted to the cylinder hole is provided. 2. The method according to claim 1, wherein the ram is formed as a hollow body and the liquid surface acting surface is provided in two directions, an axial direction and a radial direction.