JP2023083750A - Mold clamping device - Google Patents

Abstract

To provide a mold clamping device capable of adjusting an optimum pressing position and an optimum pressing amount when clamping a mold and decreasing deformation of the mold as much as possible with a simple configuration.SOLUTION: A mold clamping device disposes a die between a fixed platen and a movable platen and performs mold clamping by moving the movable platen by a mold clamping ram 15. Between a counter-mold fitting surface of the movable platen and a movable platen opposite surface 15a of the mold clamping ram 15, a surface pressure adjusting member 21 capable of adjusting a pressing position and a pressing amount is interposed. The mold clamping ram 15 is provided with a first engagement part 17 on the surface pressure adjusting member facing surface 15a, the surface pressure adjusting member 21 is provided with a second engagement part 23 to be detachably engaged to the first engagement part 17 on a mold clamping facing surface 21b, and the surface pressure adjusting member 21 is provided with a protruded face part 25 on a first surface 21a facing the counter-mold fitting surface 13a of the movable platen 13.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to an improvement of a mold clamping device incorporated in an injection molding apparatus or the like, particularly a direct pressure type mold clamping device that directly generates a mold clamping force by means of a hydraulic cylinder.

For example, in a mold clamping device incorporated in an injection molding machine or the like, a stationary platen on which a fixed mold is arranged and a cylinder portion of a mold clamping cylinder are connected by tie bars, and a movable platen on which a movable mold is arranged between them. are configured to be movable along the tie bars.
Direct pressure type, toggle type, etc. are widely known as mold clamping devices. and the movable mold are opened and closed, and the mold is clamped. Then, the nozzle of the heating cylinder of the injection device is brought into close contact with the sprue bush of the fixed mold, the molten resin is injected from the heating cylinder into the mold cavity, and after the resin in the mold cavity solidifies, the mold clamping ram is Move backward, open the mold and take out the molded product.

The conventional mold clamping device has the following problems.
Conventionally, in a general mold clamping device 3, the mold clamping ram 5 of the mold clamping cylinder 7 has its movable platen facing surface (top surface) 15a in direct contact with the ram facing surface (bottom surface) 13a of the movable platen 13. It was fixed (see Fig. 8).
The mold clamping force of the mold clamping ram 15 deforms the fixed platen and the movable platen, for example, so that uneven contact pressure may occur between the mating surfaces of the fixed mold and the movable mold.

Such non-uniform surface pressure on the mold mating surfaces may lead to deterioration in accuracy of the molded product, such as non-uniform thickness.
In addition, for example, in the case of a large size mold, the contact pressure is high in the central part and decreases toward the end (periphery) part, so the end (periphery) part with low contact pressure There may be a problem that burrs are generated in the On the other hand, in the case of small-sized molds, the contact pressure is low in the center part, and the contact pressure increases toward the end (periphery). A problem may arise in that the thickness of the center portion of the product differs from the thickness of the edge portions.
In particular, in the case of products whose product thickness is important (for example, thin-walled products such as optical discs, etc.), the influence of such mold deformation is extremely high.
The problem of mold deformation can be solved, for example, by increasing the rigidity, but it is difficult in reality, and this solution cannot be adopted at all. Due to the size problem, this solution causes an increase in the size of the entire apparatus, and is absolutely impossible to adopt.

Therefore, conventionally, as with the configurations disclosed in Patent Literature 1 and Patent Literature 2, various solutions have been proposed, but all of them have complicated configurations or poor workability and production efficiency. However, technical means capable of actually solving this problem have not been adopted.
The inventors of the present invention have focused on equalizing the surface pressure of the mating surfaces by synchronizing the amount of deformation of the upper and lower molds while considering the deformation of the molds during mold clamping. As a result, the inventors have arrived at the present invention.

Patent No. 3438810 Patent No. 3219808

The present invention has been made to solve such problems, and its object is to adjust the optimum pressing position and pressing amount at the time of clamping the mold with a simple structure, and uniform the surface pressure of the mold. It is an object of the present invention to provide a mold clamping device that can be

In order to achieve the above object, the first present invention is a mold clamping device in which a mold is arranged between a fixed platen and a movable platen, and the movable platen is moved by a mold clamping ram to clamp the molds. ,
A surface pressure adjusting member (ram spacer) capable of adjusting a pressing position and pressing amount is interposed between the surface of the movable platen opposite the mold and the surface of the mold clamping ram facing the movable platen,
The mold clamping ram is provided with a first engaging portion on the surface facing the surface pressure adjusting member,
The surface pressure adjusting member is provided with a second engaging portion that is detachably engaged with the first engaging portion on the surface facing the mold clamping ram,
The mold clamping device is characterized in that the surface pressure adjusting member is provided with a convex surface portion on the first surface portion of the movable platen opposite to the mold installation surface.

A second aspect of the present invention is a mold clamping device according to the first aspect of the present invention, characterized in that the convex surface portion is provided around the edge region of the first surface portion continuously with a ridge. That is.

According to a third aspect of the present invention, in the first aspect of the present invention, the mold clamping device is characterized in that the convex portion protrudes in a small-diameter columnar shape from the central region of the first surface portion. be.

According to the present invention, it is possible to provide a mold clamping device that can adjust the optimum pressing position and pressing amount at the time of clamping the molds with a simple structure, and can equalize the surface pressure of the molds.

1 is a schematic view of an injection molding apparatus incorporating a mold clamping device of the present invention; FIG. FIG. 3 is a partial enlarged view showing an enlarged surface pressure adjusting member portion, which is an essential part of the mold clamping device of the present invention; FIG. 4 is a partially enlarged view showing a surface of the mold clamping ram facing the surface pressure adjusting member by removing the surface pressure adjusting member; FIG. 3 is a longitudinal sectional view of FIG. 2; 1 is a perspective view showing an embodiment of a surface pressure adjusting member; FIG. FIG. 5 is a perspective view showing another embodiment of the surface pressure adjusting member; FIG. 2 is a partially enlarged cross-sectional view showing a main part of the embodiment; FIG. 10 is a partially enlarged cross-sectional view showing the main part of the prior art;

A mold clamping device according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that this embodiment is merely one embodiment of the present invention and is not limited in any way, and design changes are possible within the scope of the present invention.
"First Embodiment"

The mold clamping device 3 of this embodiment is a direct pressure type mold clamping device that directly generates a mold clamping force by means of a mold clamping cylinder (hydraulic cylinder) 7, and is incorporated in the vertical injection molding machine 1. A stationary platen 5 on which a fixed mold is arranged and a cylinder portion 9 of a mold clamping cylinder 7 are connected by tie bars 11, and a movable platen 13 on which a movable mold is arranged between them is movable along the tie bars 11. It is configured. In the drawings, dies (fixed dies and movable dies) are omitted from illustration.
The mold clamping ram 15 of the mold clamping cylinder 7 advances and retracts the movable platen 13 to open and close the fixed mold and the movable mold and to clamp the mold.
The present invention is characterized in that a surface pressure adjusting member 21 is interposed between the surface 13a of the movable platen 13 opposite to the mold mounting surface 13a and the surface 15a of the mold clamping ram 15 facing the movable platen. Therefore, in this specification, only the characteristic portions of the present invention will be described, and detailed descriptions of the other components will be omitted because the design of other components can be appropriately changed within the scope of the present invention.

The overall shape of the mold clamping ram 15 is formed in a columnar shape like a general mold clamping ram. 15a is provided with a first engaging portion 17 (see FIGS. 3, 4 and 7).

In the present embodiment, the first engaging portion 17 is a cylindrical projection having a short diameter and a small diameter in the central region of the surface 15a facing the surface pressure adjusting member.
The first engaging portion 17 is detachably engaged with a second engaging portion 23 provided on the bottom surface 21b of the surface pressure adjusting member 21, that is, the mold clamping ram opposing surface 21b. Functions as an alignment protrusion.

Further, in this embodiment, a plurality of fixing holes 19 are formed on the PCD (Pitch Circle Diameter) near the outer periphery of the surface 15a facing the surface pressure adjusting member (see FIGS. 3 and 4). and Figure 7).

The surface pressure adjusting member (also referred to as a ram spacer) 21 has a form as shown in FIG. 5, for example, in this embodiment.

In this embodiment, the entirety is formed in a short columnar shape (also referred to as a disk shape) having the same diameter as the surface 15a of the mold clamping ram 15 facing the surface pressure adjusting member.
The surface pressure adjusting member 21 is provided with a convex surface portion 25 on a first surface portion (surface facing the movable platen) 21a, which is the top surface facing the surface opposite the mold (surface facing the surface pressure adjusting member) 13a of the movable platen 13. (See Figures 2, 4 and 5.)

The convex surface portion 25 is provided around the edge area of the first surface portion 21a so as to be continuous with the ridge. In this embodiment, the outer peripheral edge of the convex portion 25 is chamfered (see FIG. 5).
The convex surface portion 25 is formed in an annular shape with a uniform width extending inward from the outer peripheral edge of the upper end of the side surface 21c of the surface pressure adjusting member 21 by a predetermined length, and is circumferentially provided at a uniform predetermined height from the first surface portion 21a. ing.
The convex portion 25 has a fixing hole 27 for connecting the movable platen and a fixing hole 29 for connecting the movable platen, the surface pressure adjusting member and the mold clamping ram, respectively, on the top surface (first surface portion) of the convex portion 25. A plurality of perforations are drilled from 21a to the bottom surface (surface facing the mold clamping ram) 21b of the surface pressure adjusting member 21 .

The surface pressure adjusting member 21 is detachably engaged with a first engaging portion 17 protruding from the surface 15a of the mold clamping ram 15 facing the surface pressure adjusting member on a bottom surface (surface facing the mold clamping ram) 21b. Two engaging portions 23 are provided (see FIGS. 4 and 7).

The second engaging portion 23 engages the first engaging portion 17 with the central region of the mold clamping ram opposing surface 21 b of the surface pressure adjusting member 21 so as to be able to engage with the first engaging portion 17 . It has a single cylindrical recess with a compatible diameter and depth.

According to the present embodiment, the surface pressure adjusting member 21 is interposed between the movable platen 13 and the mold clamping ram 15 in this manner, and the surface pressure adjusting member 21 is positioned on the surface of the movable platen 13 opposite to the mold installation surface 13a. Since the ring-shaped convex surface portion 25 is provided around the edge region of the first surface portion 21a opposed to the first surface portion 21a, the deformation of the mold can be reduced as much as possible by the simple work of setting the surface pressure adjusting member 21 on the mold clamping ram 15. can be done.
In other words, when molding a product using a large-sized mold, the surface pressure is high at the center portion when the mold is clamped, and the surface pressure decreases toward the end (periphery) portion. Therefore, burrs may occur at the end (periphery) where the surface pressure is low. According to the present embodiment, since the surface pressure adjusting member 21 in which the annular convex portion 25 abuts at the position corresponding to the end (periphery) region where the surface pressure is low, the surface pressure of the end (periphery) region where the surface pressure was low is reduced. Since it is possible to increase the surface pressure close to the central portion, it is possible to minimize the occurrence of burrs and distortion of the product.
In addition, it is possible to simply replace the optimum surface pressure adjusting member according to the mold, and the mold clamping ram can be easily handled without any structural change, so that work efficiency and productivity are improved.
Furthermore, the first engaging portion 17 is provided on the surface 15a of the mold clamping ram 15 facing the surface pressure adjusting member, and the first engaging portion 17 is detachably attached to the surface 21b of the surface pressure adjusting member 21 facing the mold clamping ram. Since the second engaging portion 23 to be engaged is provided, alignment is facilitated when the surface pressure adjusting member 21 is set, and work efficiency is improved.

In the present embodiment, the first engaging portion 17 is projected in a single columnar shape from the central region of the surface 15a facing the surface pressure adjusting member of the mold clamping ram 15, and the second engaging portion 23 is formed in the A single cylindrical recess is provided in the central region of the mold clamping ram facing surface 21b of the surface pressure adjusting member 21 so as to be able to engage with the one engaging portion 17, but the interpretation is limited to this. Instead, it is sufficient that it has an alignment function, and its shape can be changed in design within the scope of the present invention. For example, the first engaging portion 17 is prismatic, and the second engaging portion 23 is recessed in a rectangular tubular shape so that the first engaging portion 17 having a prismatic shape can be engaged. may be Furthermore, a configuration in which a plurality of first engaging portions 17 and a plurality of second engaging portions 23 are provided is also within the scope of the present invention, and in this case, various shapes are combined. may
Moreover, it is also possible to reverse the configuration of the present embodiment. For example, a configuration in which the first engaging portion is recessed and the second engaging portion is protruded may be employed.
"Second embodiment"

For the surface pressure adjusting member 21, for example, a form as shown in FIG. 6 is also assumed.

The surface pressure adjusting member 21 of the present embodiment can be employed particularly in the case of a small-sized mold, and is formed in a disk shape having the same diameter as the surface 15a facing the surface pressure adjusting member of the mold clamping ram 15. A convex portion 25 is provided in a columnar shape in a central region of the portion 21a.
In this embodiment, the convex portion 25 has a diameter about half that of the first surface portion 21a.
Further, in this embodiment, a plurality of fixing holes 27 for connecting the movable platen are formed on the convex portion 25 on the PCD (Pitch Circle Diameter). In addition, a plurality of fixed holes 29 for connecting the movable platen, the surface pressure adjusting member and the mold clamping ram are drilled on the PCD (Pitch Circle Diameter) near the outer periphery of the first surface portion 21a. ing.

In the case of small-sized molds, the surface pressure is low in the central part, and the surface pressure may increase toward the end (periphery). However, according to the present embodiment, the convex portion 25 protruding in a cylindrical shape corresponds to the central portion where the surface pressure is low. Since the contacting surface pressure adjusting member 21 is used, it is possible to increase the surface pressure at the central portion where the surface pressure was low and approach the surface pressure at the end (periphery) portion, making it possible to make the thickness of the product uniform. is.
Since other configurations and effects are the same as those of the above-described embodiment, detailed description thereof will be omitted.

Further, the surface pressure adjusting member (ram spacer) 15 can be configured as follows, and the design can be appropriately changed within the scope of the present invention.
For example, it is possible to change the diameter of the convex portion of the first embodiment, and it is also possible to make the convex portion have other shapes such as an elliptical convex shape in plan view. Furthermore, it is also possible to employ a combination of the convex portion of the first embodiment and the convex portion of the second embodiment.

It can be incorporated into other types of injection molding machines, and can be used in both vertical and horizontal injection molding machines.

1 Injection molding device 3 Mold clamping device 5 Fixed platen 7 Mold clamping cylinder 9 Cylinder part 11 Tie bar 13 Movable platen 13a Anti-mold setting surface 15 Mold clamping ram 15a Movable platen facing surface (face pressure adjusting member facing surface)
17 first engaging portion 21 surface pressure adjusting member (ram spacer)
21a top surface (first surface portion)
21b bottom (face opposite mold clamping ram)
21c side surface 23 second engaging portion 25 convex portion 27 fixing hole 29 for connecting movable platen fixing hole for connecting mold clamping ram

Claims (3)

A mold clamping device that disposes a mold between a fixed platen and a movable platen, and clamps the mold by moving the movable platen with a mold clamping ram,
interposing a surface pressure adjusting member capable of adjusting a pressing position and a pressing amount between the surface of the movable platen opposite the mold and the surface of the mold clamping ram facing the movable platen,
The mold clamping ram is provided with a first engaging portion on the surface facing the surface pressure adjusting member,
The surface pressure adjusting member is provided with a second engaging portion that is detachably engaged with the first engaging portion on the surface facing the mold clamping ram,
A mold clamping device, wherein the surface pressure adjusting member has a convex surface portion on a first surface portion facing a surface of the movable platen opposite to the mold arrangement surface. 2. The mold clamping device according to claim 1, wherein the convex surface portion is provided around the edge area of the first surface portion so as to be continuous with the ridge. 2. A mold clamping device according to claim 1, wherein said convex surface portion projects in a small-diameter columnar shape from a central region of said first surface portion.

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