JP2770655B2 - Mold clamping device for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molding mold clamping apparatus provided in an injection molding machine such as a die casting machine or an injection molding machine for clamping a movable mold and a fixed mold by pressing them together. is there.

[0002]

2. Description of the Related Art Injection molding machines such as die casting machines and injection molding machines are classified into vertical molds and horizontal molds according to their mold clamping directions, and vertical injection molds according to the injection direction of a molten material or a plastic material. And a horizontal injection type. Of these, for example, a horizontal clamping horizontal injection type die casting machine is generally configured as follows. That is, tie rods extending in the horizontal direction are supported at the four corners of a fixed platen that is erected on the machine base with the mold mounting surface facing sideways. The cylinder platen opposed to the vertical plane is fixed by a nut screwed into the screw portion of the tie rod.

[0003] A movable platen is provided between the fixed platen and the cylinder platen with four corner holes slidably fitted on 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.
On the opposing surfaces of the fixed platen and the movable platen, a fixed mold and a movable mold whose planes are opposed to each other are attached. Further, the plunger tip of the injection cylinder supported on the fixed platen side is fitted to the injection sleeve supported on the injection cylinder side so as to be able to advance and retreat.
The injection sleeve is detachably joined to a fixed sleeve on the fixed platen side, and an inner hole of the fixed sleeve is communicated with a cavity of the mold via a runner of the fixed mold.

[0004] With this configuration, when the main ram advances by hydraulic pressure, the movable platen integrated with the main ram moves with the movable mold and is clamped to the fixed mold. Then, when the molten metal is injected into the injection sleeve and joined to the fixed sleeve, and the plunger tip is advanced by the hydraulic pressure of the injection cylinder, the molten metal in the injection sleeve is injected into the mold cavity through the fixed sleeve and the runner. You. Then, after the molten metal in the cavity is solidified, when the piston rod of the mold clamping cylinder is retracted, the movable mold is retracted and the mold is opened, so that the product which is the molten metal solidified product held in the movable mold is removed. Withdrawing completes one injection cycle.

[0005]

However, in such a conventional mold clamping apparatus for injection molding, when the movable platen is moved by the mold clamping cylinder and the mold is clamped, the movable platen and the fixed metal which hold the movable mold are provided. Since the fixed platen holding the mold is pressed more strongly at the central portion than at the four peripheral portions, the movable platen and the fixed platen bend so that the central portion is separated more than the four peripheral portions.
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 also bends, and the shape of the mold cavity changes, so that a molded product having an accurate shape and dimensions cannot be obtained. Will erupt. In particular, if small foreign matter adheres or is scratched near the outer periphery of the mating surface of the mold, the molten material leaks vigorously from the gap of the mold, and it is dangerous. There is a problem that burrs are formed and must be removed, which lowers the work efficiency after taking out the product.

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 there is a problem that the installation space of the entire injection molding apparatus is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in view of the above circumstances. A mold clamping apparatus for injection molding which has reduced the curvature of a mold during mold clamping and has reduced the installation space of the entire apparatus. It is intended to provide.

[0009]

In order to achieve the above object, according to the present invention, a mold mounting plate is superimposed on a fixed platen having a plurality of tie rods extending in the direction of a movable platen at corners. A plurality of cylinders that are supported and open to the mold mounting plate side and connected to a hydraulic pressure source
Circumferentially divides the hole around the center of the fixed platen in the circumferential direction
Provided at a position around the point that, even provided integrally ram slidably fitted in the respective cylinder holes in the mold mounting plate
It is.

[0010]

According to the present invention, after the movable platen to which the movable mold is fixed is moved to match the movable mold with the fixed mold, oil is fed to the cylinder hole of the movable platen.
Each ram moves within each cylinder hole, and a mold mounting plate integral with these rams moves to perform mold clamping. At the time of this mold clamping, since the ram integrated with the mold mounting plate is pressed by the hydraulic pressure in each cylinder hole, the mold hardly bends, and thereafter the molten material is injected into the mold cavity. Also, the melt does not erupt from the mold mating surface to form a flash.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS This embodiment shows an example in which the present invention is applied to a die-casting machine of a horizontal clamping horizontal injection type. FIG. 1 is a partially cutaway front view of the die-casting machine in which the present invention is applied, and FIG. FIG. 3, FIG. 3 is a side view as viewed in III of FIG. 1, FIG. 4 is a side view as viewed in IV of FIG. 1, FIG.
FIG. 6 is an enlarged sectional view taken along the line VI-VI of FIG.

In FIG. 1, stepped rod holes 2a shown in FIG. 6 are formed at four corners of a fixed platen 2 having a base fixed to a machine base 1 and erected. Has one end of the tie rod 3 inserted therein.
A nut 4 inserted into the rod hole 2a is screwed into a threaded end of the tie rod 3. In addition, tie rod 3
Is fixed to the end face of the tie rod 3 by bolts 7 and the tie rod 3 is fixed to the end face of the tie rod 3 by a bolt 7.
Is fixed to the fixed platen 2 with its rotation restricted.

On the other hand, the anti-fixed platen 2 of the machine base 1
At the end on the side, a connecting plate 8 formed in a substantially square frame shape
Each leg is slidably fitted to a plate-like rail 1 a provided on the machine base 1, and each of the rod holes formed at four corners of the frame of the connecting plate 8 has , Fixed platen 2
The other ends of the four tie rods 3 extending in the horizontal direction are inserted through the spanning ring 9, whereby the rotation of the tie rods 3 is restricted and the connecting plate 8 is
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 has an upright vertical surface opposed to the upright planar surface of the fixed platen 2;
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 and 11a provided on the movable platen 10 and the guide shoe 11 by adjusting the horizontal bolts for fixing the movable platen 10 and the guide shoe 11. It is configured.

Further, each of the four tie rods 3 is engaged with a concave hole 10c provided at each of the four corners of the movable platen 10.
A ball screw nut 12 formed in a cylindrical shape is interposed between the concave hole 10 c and the tie rod 3 so as to be rotatable and movable in the axial direction via a needle bearing 13. Movable platen 10 of tie rod 3
A screw groove 3b having a semicircular cross section is provided in approximately half of the side, and a plurality of balls 14 held in a hemispherical concave hole of the ball screw nut 12 are rollable in the screw groove 3b. Is engaged. Thus, when the ball screw nut 12 is rotated by the driving device described later, the movable platen 10 is configured to advance and retreat 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.

A movable mold 15 is removably mounted on a 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 of FIG.
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.

Therefore, a rotation driving device for the ball screw nut 12 will be described. In FIGS. 3 and 6, a bearing plate 17 formed in a frame shape having a substantially square upright edge is bolted to a vertical end face of the movable platen 10 on the side of the connecting plate 8, and each of the four balls One end of the screw 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,
Three sprockets 22, 23, 24, 25 are respectively fixed to the center holes by penetrating the tie rods 3, and two sprockets 27 having an electromagnetic brake 26 are provided between the upper sprockets 22, 23. But the bearing plate 17
And is fixedly provided on a shaft 28 which is rotatably supported. Further, between the sprockets 22 and 27 and between the sprockets 23 and 27, idle sprockets 29 and 3 are provided.
0 are pivotally mounted on the bearing plate 17, respectively.
A chain 31 is stretched between the sprockets 22, 23, 30, 27, and 29.

Further, between the lower sprockets 24 and 25, two sprockets 32 are provided rotatably supported by the bearing plate 17. Also, sprocket 2
Idle sprockets 33 and 34 are provided between the sprockets 24 and 32 and the sprockets 25 and 32 so as to be pivotally mounted on the bearing plate 17, respectively.
A chain 35 is stretched between 25, 34, 32, and 33.

Further, an idle sprocket 36 and a sprocket 37 with an electromagnetic brake are provided between the upper and lower sprockets 22 and 24 while being supported by the bearing plate 17, and these sprockets 22, 24, 36 and 37 are provided.
A single chain 38 is stretched between them. Also,
An idle sprocket 39 and a sprocket 41 with an electromagnetic brake 40 are provided between the upper and lower sprockets 23 and 25.
Are supported by the bearing plate 17, and a single chain 42 is stretched between the sprockets 23, 25, 41, and 39. Thus, when the movable platen 10 is moved by the movable cylinder 43 to be described later to open and close the mold, the ball screw nut 12 rotates while moving in the mold opening and closing direction.
Since 2, 23, 24, and 25 rotate simultaneously, the movable platen 10 moves smoothly. By stopping the operation of the moving cylinder 43, the electromagnetic brakes 26, 40
By operating the same, the four ball screw nuts 12 are suddenly stopped at the same time.

A moving cylinder 43 for the movable platen 10 is fixed to the upper end on one side and the lower end on the other side of the fixed platen 2, and the working end of the piston rod 44 is connected to the bearing plate. 17 are fixed to both side surfaces. By doing so, the bearing plate 17 and the movable platen 10 move forward and backward by the action of the piston rod 44 when the mold is set and the mold is opened, and are provided between the bearing plate 17 and the movable platen 10 by retracting the piston rod 44 when the mold is clamped. The bearing plate 17 is moved to the movable platen 10 without a slight gap.
It is configured to be pressed against.

In this apparatus, 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 rod holes at four corners are slidably fitted to the tie rods 3.
Are formed on the surface of the fixed platen 2 facing the mold mounting plate 45, and three circular concave holes centered on a point which divides a circle around the center of the facing surface into three equal parts in the circumferential direction. Is provided to open to the mold mounting plate 45 side.

On the other hand, a circular ram 47 slidably fitted in the cylinder hole 46 is provided on the mold mounting plate 45 side.
8, and the fixed platen 2 and the mold mounting plate 45 are bolted into the screw holes of the mold mounting plate 45 through the bolt holes of the fixed platen 2. Fixed. A compression coil spring 51 that biases the mold mounting plate 45 toward the fixed platen 2 is loaded between the head of the bolt 48 and the bottom surface of the spring hole provided in the fixed platen 2. . A packing 52 is provided on the peripheral surface of the ram 47, and the bottom surface of the cylinder hole 46 is communicated with a hydraulic pressure source via an oil passage (not shown). The mold mounting plate 47 is moved by the hydraulic pressure against the elastic force of the compression coil spring 51, and the mold is clamped.

In FIG. 4, reference numeral 53 denotes an injection cylinder mounted on the outer flat surface of the fixed platen 2, which has 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 pressing 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. 4, what is indicated by a two-dot chain 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. In FIG. 6, the movable platen 10 includes
An extrusion cylinder 54 is embedded, and is configured to extrude a product by solidification of the molten metal from the cavity of the movable mold 15 that has been opened.

The operation of the die casting machine configured as described above will be described. When the bearing plate 17 and the movable platen 10 are moved by differentially moving the movable cylinder 43 for the movable platen 10 from the mold open state shown in FIG.
2 rotates. At this time, the chains 31, 35, 38, 4
4 sprockets 22, 23, 2 on which 2 is stretched
4, 25 rotate synchronously, and 4 formed integrally with them.
The ball screw nuts 12 rotate synchronously. When the ball screw nut 12 rotates, the screw action causes the ball screw nut 12 to move on the stationary tie rod 3 with the bearing plate 17, and the movable mold 15 moves to the fixed mold 1.
6, the operation of the moving cylinder 43 is stopped, the electromagnetic brake 26 is operated, and the movable mold 15 is suddenly stopped to perform mold matching. At this time, since the oil has been drained from the head end chamber of the movable cylinder 43, the piston rod 44 moves backward with the movement of the movable platen 10.

As described above, the movable mold 15 is fixed to the fixed mold 1.
6, the piston rod 44
The movable platen 10 in which the ball screw nut 12 is built moves slightly backward with respect to the bearing plate 17 to which the working end is fixed. The movable platen 10 is pressed relatively rearward by strong mold matching, and the inner wall surface 13b of the mounting member 13a to which the needle bearing 13 is mounted is a ball screw whose rotation is regulated by the action of the electromagnetic brake 26. It is pressed against the distal end surface 12a of the nut 12, and the distal end surface 12a of the ball screw nut 12 and the mounting member 1
The slight gap formed between the inner wall surface 13b and the inner wall surface 3b of the movable die 3a is eliminated, and the movement of the movable mold 15 and the movable platen 10 is braked without any backlash by the ball screw device. Also, since the tie rod 3 is fixed at both ends via the spanning rings 5, 9, the tie rod 3 is not twisted.

After the molds are matched in this manner, when oil is press-fitted between the end surfaces of the three rams 47 provided on the mold mounting plate 45 and the bottom surface of the cylinder hole 46, the rams 47 and the integral rams 47 are formed. The fixed platen 2 moves slightly with the fixed mold 16 against the elastic force of the compression coil spring 51, and mold clamping is performed. At the time of this mold clamping, the mold mounting plate 45 is pressed at the center thereof by the mold clamping cylinder composed of the cylinder hole 46 and the ram 47 by the movement of the ram 47, so that the movable platen 10 is moved by the electromagnetic brake 26 and the ball screw device. In addition to the fact that both are firmly braked, the movable mold 15
And the fixed mold 16 do not bend, and the movable mold 15
There is no gap in the joint surface between the metal mold and the fixed mold 16.

After the mold is clamped in this way, the molten metal is injected into the injection sleeve, and the plunger tip is advanced in the injection sleeve by hydraulic pressure, whereby the molten metal is injected into the mold cavity. At the time of this injection, no gap is formed in the joint surface between the movable mold 15 and the fixed mold 16 as described above, and even if the molten metal is injected into the cavity, both molds 1
Since the molten metal does not erupt from the joint surfaces 5 and 16,
As well as improving safety, a cast product with an accurate shape and dimensions can be obtained reliably and easily.

After the molten metal injected into the mold cavity is solidified in this way, the oil in the cylinder hole 46 is drained,
In addition, the brake by the electromagnetic brake 26 is released, and the movable cylinder 43 is operated to open the mold. At this time, the mold is opened smoothly by the operation of the ball screw device. Since the product obtained by solidification of the molten metal is held and moved by the movable mold 15, the product is extruded from the mold cavity by the extrusion cylinder 54, and is taken out of the machine by the product take-out device. The casting cycle is completed.

If the mold clamping force and the firing force are known,
Since the deformation dimensions of the fixed mold 16 and the center of the axis of the fixed platen 2 can be known in advance by calculations and experiments, the advance amount and pressure of each 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 using, for example, an ultrasonic wave, a photoelectric tube, a piezoelectric element, or the like, and the amount of advance of each ram 47 is controlled in accordance with the detected amount. Can be prevented from being deformed.

In this embodiment, the cylinder hole 4
An example is shown in which three mold clamping cylinders each comprising 6 and a ram 47 are provided, but the number is not limited, and four or more
It may be provided. Further, in the present embodiment, an example in which the present invention is applied to a horizontal mold clamping horizontal injection type die casting machine is shown, but the mold clamping direction and the injection direction are not limited, and the same applies to a plastic injection molding machine. And the same effect can be obtained.

In the above embodiment, the moving cylinder 43 is provided for moving the movable platen 10. However, the present invention is not limited to this.
Instead of 3, a motor may be attached to the sprocket 32, and the mold may be opened and closed by driving the motor.

[0034]

As apparent from the above description , the present invention
According to the injection molding mold clamping device according to the above, the mold mounting plate is overlapped and supported on a fixed platen provided with tie rods extending in the direction of the movable platen at a plurality of corners, and the mold mounting plate side To the hydraulic source
Multiple cylinder holes, circle around the center of the fixed platen
Provided at a position centered on a point equally divided in the circumferential direction,
The ram that slidably fits into the cylinder hole is provided integrally with the mold mounting plate, so that even if the platen is bent by the mold clamping force, the entire rear surface of the mold is pushed. Can be curved so that the shape,
A molded article with accurate dimensions can be obtained reliably and easily. Further , according to the present invention, 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 do not occur, and product quality is reduced. improves. Furthermore, since the operation of removing burrs is not required, the preparation time is shortened, and the operation rate of opportunities is improved. Furthermore, since the mold clamping cylinder is embedded in the fixed platen, the entire apparatus can be configured to be small and compact as compared with the conventional apparatus provided so as to protrude from the movable platen to the outside, and the installation space is reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a die casting machine embodying the present invention.

FIG. 2 is a plan view of a die casting machine embodying the present invention.

FIG. 3 is a side view as viewed in III of FIG. 1;

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

FIG. 5 is a sectional view of a mold clamping cylinder.

FIG. 6 is an enlarged sectional view taken along the line VI-VI of FIG. 3;

[Explanation of symbols]

 2 Fixed platen 3 Tie rod 10 Movable platen 45 Mold mounting plate 46 Cylinder hole 47 Ram

Claims (1)

(57) [Claims] 1. A mold mounting plate is superposed and supported on a fixed platen having a plurality of tie rods extending in the direction of a movable platen at corners, and is opened to the mold mounting plate side to provide a hydraulic power source. Multiple connected
Cylinder hole and circle around the center of the fixed platen
A ram slidably fitted in each of the cylinder holes is provided integrally with the mold mounting plate, the mold clamping plate being provided at a position centered on a point equally divided in the direction. .