JP2006327141A - Mold clamping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more effectively suppress a distortion of the PL surface of a mold by the internal pressure of a cavity by devising how to apply a mold clamping force. <P>SOLUTION: The mold clamping device comprises at least one end plate (movable side end plate 11A) arranged to the backside of at least one die plate of a fixed die plate 2 and a movable die plate 4 through a mold clamping force transmission section (movable side spacer member 10A) which transfers mold clamping force to a die plate. In the longitudinal direction of a cavity, the movable side spacer member 10A as a mold clamping force transmission section is set to be shorter than the linear dimension of the plane of projection of the cavity in the direction of mold clamping and to be 50% or more of the linear dimension of the plane of projection of this cavity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold clamping device used in, for example, an injection molding machine or a die casting machine, and more particularly to a mold clamping device that can be suitably used for injection molding or die casting of a thin and long large product.

  As a mold clamping apparatus used in an injection molding machine or a die casting machine, a direct pressure type mold clamping apparatus that generates a mold clamping force with a single large-capacity hydraulic cylinder is known.

  The direct pressure type mold clamping device includes a fixed die plate, a fixed die attached to the fixed die plate, a movable die plate disposed so as to be movable back and forth with respect to the fixed die plate, and attached to the movable die plate. A movable mold that forms a cavity between the fixed mold and the fixed mold, and a mold clamping force for clamping the fixed mold and the movable mold in a closed state. A plurality of tie bars and a large-capacity hydraulic cylinder are provided as means for generating a clamping force between the fixed die plate and the movable die plate. The fixed die plate and the cylinder body of the large-capacity hydraulic cylinder are connected to each other at four corners by four tie bars, and each tie bar is inserted into the four corners and loosely fitted to the back of the movable die plate. The piston part of the hydraulic cylinder is fixed. Thus, the movable die plate is moved forward and backward relative to the fixed die plate while being guided by each tie bar by the operation of the piston portion of the large capacity hydraulic cylinder. For this reason, when the movable die plate moves forward with respect to the fixed die plate, the fixed mold and the movable mold are closed, and a predetermined mold clamping is performed to withstand the pressure of the molten resin injected and filled in the cavity. The fixed mold and the movable mold are clamped by force.

  In such a direct pressure type clamping apparatus, when the fixed mold and the movable mold are clamped with a predetermined clamping force as described above, tension is applied to each tie bar connecting the cylinder body and the fixed die plate. ing. At this time, the fixed die plate is tightened by each tie bar at the four corners from the back side, while the pressing force from the piston portion is tightened by each tie bar through the movable die plate, the movable die and the fixed die in the central region of the fixed die plate. It works from the front side opposite to the direction. That is, a bending moment is applied to the fixed die plate so as to swell the central region toward the back side. For this reason, due to the bending deformation of the fixed die plate, the mold clamping force does not effectively act on the cavity formed between the fixed mold and the movable mold, and the cavity size is determined by the pressure of the molten resin injected and filled in the cavity. There is a problem that the accuracy of the molded product is lowered due to the change in the temperature.

  Therefore, a mold clamping device is known that can suppress the bending deformation of the fixed die plate caused by the mold clamping force (see, for example, Patent Document 1).

  In this mold clamping device, a convex portion as a mold clamping force transmitting portion is provided on the back surface of a fixed die plate having a fixed die attached to the front side, and an end plate is fixed to the fixed die plate so as to contact the convex portion. It is arrange | positioned at the back side. Then, the end plate and the cylinder body of the large-capacity hydraulic cylinder are connected with four tie bars at each of the four corners, and each tie bar is inserted and loosely fitted into the four corners of the fixed die plate and the movable die plate. A piston portion of a large-capacity hydraulic cylinder is fixed to the back surface of the movable die plate.

  In this mold clamping device, when the movable die plate is advanced relative to the fixed die plate by the operation of the piston portion and the mold clamping force is generated in the fixed mold and the movable mold, each tie bar on which the clamping load is applied Thus, the four corners of the end plate are tightened, and no tightening load is applied to the four corners of the fixed die plate that is loosely fitted to each tie bar. In the central region of the fixed die plate, the pressing force from the piston part acts from the front side through the movable die plate, the movable mold and the fixed mold, while the mold clamping force from the end plate is the mold clamping force. It acts from the back side through a convex part as a transmission part. For this reason, the bending moment as described above does not occur in the fixed die plate, and it is possible to prevent the central region of the fixed die plate from being bent and deformed so as to swell toward the back side.

  There is also known a double-acting mold clamping device that generates a mold clamping force by a plurality of hydraulic cylinders provided in each tie bar instead of the large-capacity hydraulic cylinder.

The double-acting mold clamping device includes the fixed die plate, the fixed mold, the movable die plate, the movable mold, a plurality of tie bars as a mold clamping force generating means, and a plurality of mold clamping hydraulic cylinders. And a moving hydraulic cylinder for moving the movable die plate forward and backward with respect to the fixed die plate. In this mold clamping device, the fixed die plate and the movable die plate are connected to each other at four corners by four tie bars, and a mold clamping hydraulic cylinder is provided for each tie bar. For this reason, in this mold clamping device, the movable die plate moves forward with respect to the fixed die plate by the operation of the moving hydraulic cylinder, and the fixed mold and the movable mold are closed. In this state, each mold clamping hydraulic cylinder operates. As a result, a movable die plate is attracted by each tie bar to the fixed die plate to generate a mold clamping force. With this, a predetermined mold clamping force is applied to withstand the pressure of the molten resin injected and filled into the cavity. The fixed mold and the movable mold are clamped.
Japanese Patent Publication No. 6-41160 (Fig. 1)

  By the way, when a thin and long product is injection-molded, the cavity has a thin and long shape, and in order to reliably supply molten resin to the end of the cavity, It is necessary to increase the injection pressure of the molten resin. However, when the pressure in the cavity becomes high in this way, it is difficult to completely clamp the mold against the pressure in the cavity even with the mold clamping device disclosed in Patent Document 1. For this reason, when the mold PL surface is distorted and opened due to the pressure in the cavity, burrs are generated in the PL part of the molded product, and there is a problem that a step of removing burrs is required in post-processing.

  In the double-acting type mold clamping device, the four corners of the fixed die plate and the movable die plate are clamped by each tie bar, so that the mold clamping force can effectively act on the central region in the longitudinal direction of the cavity. In this central region, the mold PL surface is easily distorted.

  The present invention has been made in view of the above circumstances, and a mold clamping device that can more effectively suppress the mold PL surface from being distorted by the pressure in the cavity by devising how to apply the mold clamping force. This is a technical problem to be solved.

  In order to solve the above-mentioned problems in the direct pressure type and double-acting type mold clamping devices, the present inventors have conducted extensive research on the occurrence of the strain on the mold PL surface and the cause thereof, and as a result, for the die plate and the mold, Focusing on the correlation between the longitudinal length of the area where the cavity pressure acts from the cavity projection surface in the mold clamping direction and the longitudinal length of the area where the clamping force acts, and adjusting the relationship between the two appropriately The present inventors have found that the occurrence of distortion on the mold PL surface can be suppressed and completed the present invention.

  That is, a mold clamping device of the present invention that solves the above-described problems includes a fixed die plate, a fixed die attached to the fixed die plate, and a movable die plate disposed so as to be movable forward and backward relative to the fixed die plate. A movable die which is attached to the movable die plate and forms a cavity corresponding to the shape of a molded product between the fixed die and the fixed die, and the closed die. In a mold clamping device comprising a fixed mold and a mold clamping force generating means for generating a mold clamping force for clamping the movable mold, at least one of the fixed die plate and the movable die plate On the back side, there is at least one end plate disposed via a clamping force transmission part that transmits the clamping force to the die plate, and the cavity has a longitudinal direction. The mold clamping force transmitting portion is set to be shorter than the length dimension of the cavity projection surface in the mold clamping direction and to be 50% or more of the length dimension of the cavity projection surface. It is what.

  Here, the “longitudinal direction of the cavity” means, for example, the longitudinal direction of the cavity when molding a long product means the direction in which the cavity extends long, and the longitudinal direction of the cavity when molding a circular product is It means the diameter direction of the cavity, and the longitudinal direction of the cavity in the case of forming a square product means the direction of one side of the positive direction.

  Further, “in the longitudinal direction of the cavity, the clamping force transmission portion is set to be shorter than the length dimension of the cavity projection surface in the clamping direction and at least 50% of the length dimension of the cavity projection surface. "The length of the clamping force transmission part in the longitudinal direction of the cavity is shorter than the longitudinal dimension of the cavity projection surface of the cavity projection surface in the mold clamping direction, and the length of the cavity projection surface". It means that it is set to 50% or more of the size.

  In this mold clamping device, the mold clamping force generating means is operated in a state where the movable die plate moves forward relative to the fixed die plate and the fixed mold and the movable mold are closed, so that the cavity is injected and filled. The fixed mold and the movable mold are clamped with a predetermined clamping force to withstand the pressure of the molten resin or the like. At this time, in the die plate in which the end plate is disposed on the back side, the clamping force acts on the die plate from the end plate via the clamping force transmitting portion. In the mold clamping device of the present invention, the mold clamping force transmitting portion is shorter than the length dimension of the cavity projection surface in the mold clamping direction in the longitudinal direction of the cavity, and is 50 of the length dimension of the cavity projection surface. % Length is set. For this reason, as shown below, the longitudinal length of the range in which the pressure in the cavity acts from the cavity projection surface in the mold clamping direction and the mold clamping force are applied to the die plate and the mold attached to the die plate. The relationship with the length in the longitudinal direction of the acting range becomes appropriate, and as a result, the PL plate of the die plate and the die attached to the die plate can be effectively suppressed from being distorted by the pressure in the cavity. Therefore, it is possible to effectively suppress the occurrence of burrs in the PL part of the molded product.

  That is, if the length dimension of the mold clamping force transmitting portion that applies the mold clamping force to the die plate or the mold is longer than or equal to the length dimension of the cavity projection surface, the mold clamping force counters the cavity pressure. In general, it can be expected that the die plate and the mold can be effectively prevented from being distorted by the pressure in the cavity. However, according to experiments by the present inventors, when the length dimension of the clamping force transmission part is longer than or equal to the length dimension of the cavity projection surface, the pressure in the cavity is increased in both end regions in the longitudinal direction of the cavity. Although it was possible to suppress the distortion of the die plate and the mold due to the above, it was found that the distortion of the die plate and the mold due to the pressure in the cavity cannot be effectively suppressed in the central region in the longitudinal direction of the cavity.

  For this reason, as shown in FIG. 7, in the longitudinal direction of the cavity, in the configuration in which the clamping force transmission portion has a length dimension equal to or greater than the length dimension of the cavity projection surface, In the central area, the clamping force from the clamping force transmission part does not work effectively, and the mold PL surface is distorted so that it swells outward in the direction opposite to the clamping direction. Burr will occur in the PL part.

  7 to 9, in the longitudinal direction of the cavity, the distortion of the mold PL surface varies depending on the relationship between the length dimension of the cavity projection surface in the mold clamping direction and the length dimension of the mold clamping force transmitting portion. The situation is shown schematically.

  On the other hand, when the length dimension of the mold clamping force transmission part becomes extremely shorter than the length dimension of the cavity projection surface, the die plate and the mold are distorted by the pressure in the cavity in the region where the mold clamping force does not act. End up. For this reason, as shown in FIG. 8, in the configuration in which the length dimension of the mold clamping force transmission part is less than 50% of the length dimension of the cavity projection surface in the longitudinal direction of the cavity, the mold clamping force transmission part There is no mold clamping force, and there is distortion that the mold PL surface bends outward in the direction opposite to the mold clamping direction in the region on both ends in the longitudinal direction of the cavity. Burr will occur in the PL part.

  On the other hand, in the mold clamping device of the present invention, since the length dimension of the mold clamping force transmission portion is appropriately set with respect to the length dimension of the cavity projection surface, as shown in FIG. A force that generates a strain such that the mold PL surface bulges outward in the central region in the longitudinal direction of the cavity, and a force that generates a strain such that the mold PL surface bends outward in both end regions in the longitudinal direction of the cavity; Is well balanced, and distortion generated on the mold PL surface by the pressure in the cavity can be suppressed.

  In a preferred aspect of the mold clamping device of the present invention, the mold clamping force transmission portion is set to a length dimension of 75 to 95% of the length dimension of the cavity projection surface.

  In this mold clamping device, since the length dimension of the mold clamping force transmitting portion is more appropriately set with respect to the length dimension of the cavity projection surface, distortion generated on the mold PL surface due to the pressure in the cavity is reduced. It becomes possible to suppress more effectively.

  Here, it is more preferable that the mold clamping force transmission portion is set to a length dimension of 80 to 92% of the length dimension of the cavity projection surface.

  In a preferred aspect of the mold clamping device of the present invention, the mold clamping force generating means connects the outer peripheral area of the end plate and the outer peripheral area of the fixed die plate or the movable die plate, or both the ends. A plurality of tie bars for connecting the outer peripheral areas of the part plates, and a plurality of tension applying means for applying tension to each of the tie bars to generate the clamping force.

  In this mold clamping device, the mold clamping force generating means has a plurality of tension applying means for applying tension to each of the plurality of tie bars that connect the end plate and the fixed die plate, and so-called double-acting type. Therefore, as compared with the direct pressure type in which a large-capacity hydraulic cylinder or the like must be used, the entire apparatus can be reduced in size.

  In a preferred aspect of the mold clamping device of the present invention, the mold clamping force transmission portion is constituted by a spacer member provided separately from the die plate and the end plate.

  In this mold clamping device, since it can be divided into a die plate, an end plate, and a spacer member as a mold clamping force transmission part, the mold clamping force transmission part is integrated with the die plate or the end plate. Compared with the case where it exists, it becomes possible to improve the transportability and handleability of an apparatus.

  In a preferred aspect of the mold clamping device of the present invention, the molded product is a long molded product. When molding a long molded product, it is more difficult to balance the clamping force and the pressure in the cavity in both the central region and both end regions in the longitudinal direction of the cavity. According to the clamping device, even when a long molded product is molded, the mold clamping force and the pressure in the cavity can be well balanced in both the central region and both end regions in the longitudinal direction of the cavity. It becomes possible, and the distortion which generate | occur | produces in the metal mold | die PL surface by the pressure in a cavity can be suppressed favorably.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The mold clamping apparatus of this embodiment shown in FIGS. 1 and 2 is used when injection molding the thin long product 1 as the resin molded product shown in FIG. A fixed die 3 attached to the die plate 2, a movable die plate 4 disposed so as to be movable back and forth with respect to the fixed die plate 2, a movable die 5 attached to the movable die plate 4, a fixed die 3 and Clamping force generating means 6 for clamping the movable mold 5 is provided.

  FIG. 1 is a side view schematically showing the overall configuration of the mold clamping device of this embodiment, and FIG. 2 is a partial perspective view in which the main part of the mold clamping device is divided into four at the center line O of the device. It is. The thin long product 1 has a longitudinal length (L) of 1200 mm, a width of 45 mm, and a thickness (t) of 3.5 mm.

  The fixed die 3 is fixed to the fixed die plate 2 with a bolt or the like (not shown), and the fixed die plate 2 is fixed on a base (not shown). The movable die 5 is fixed to the movable die plate 4 by bolts or the like (not shown), and the movable die plate 4 is disposed on the same base so as to be movable back and forth with respect to the fixed die plate 2. The fixed mold 3 and the movable mold 5 have a mold surface of a predetermined shape that forms a cavity 7 corresponding to the shape of the molded product between the two in a closed state. The plate thickness (T) of the fixed die plate 2 and the movable die plate 4 is 300 mm.

  The fixed die plate 2 is provided with a cavity 9 through which the injection nozzle 8 is inserted and accommodated, and the molten resin is injected and filled into the cavity 7 from the injection nozzle 8. At this time, the molten resin is injected into the cavity 7 from one end of the cavity 7 in the longitudinal direction (the vertical direction in FIG. 1 and the horizontal direction in FIG. 2) (see FIG. 1). Further, the thickness direction of the cavity 7 (left and right direction of the cavity 7 shown in FIG. 1) corresponding to the thickness direction of the thin long product 1 is the mold clamping direction (the center line O shown in FIG. A cavity 7 is provided so as to coincide with the extending direction.

  The mold clamping device of this embodiment is disposed on the back side of the movable die plate 4 via a movable side spacer member 10 </ b> A as a mold clamping force transmission unit that transmits a mold clamping force to the movable die plate plate 4. In addition, it has a movable end plate 11A. The movable die plate 4, the movable side spacer member 10A, and the movable side end plate 11A are integrally fixed by a bolt or the like (not shown). The movable spacer member 10A has a disk shape with a diameter (D) of 1100 mm and a thickness of 75 mm. In addition, four insertion holes 12 through which each tie bar described later can be inserted are provided at four corners of the fixed die plate 2 and the movable side end plate 11A (see FIG. 2). In addition, four cutout step portions 13 that avoid interference with each tie bar are provided at the four corners of the movable die plate 4 (see FIG. 2). Similarly to the movable die plate 4, the movable side end plate 11 </ b> A is disposed on the base so as to be movable back and forth with respect to the fixed die plate 2.

  Then, a moving hydraulic cylinder (not shown) as moving means for moving the movable side end plate 11A, the movable side spacer member 10A, the movable die plate 4 and the movable mold 5 integrally with respect to the fixed die plate 2 is shown. Is fixed on the base, and the piston portion of the moving hydraulic cylinder is coupled to the movable side end plate 11A. By the operation of the moving hydraulic cylinder, the movable side end plate 11A and the like move forward with respect to the fixed die plate 2, so that the fixed die 3 attached to the fixed die plate 2 and the movable die plate 4 are attached. The movable mold 5 is closed.

  The mold clamping force generating means 6 generates a mold clamping force for clamping the fixed mold 3 and the movable mold 5 in a closed state. The mold clamping force generating means 6 includes four corners as outer peripheral areas of the fixed die plate 2 and movable mold ends. The four tie bars 14 that connect the four corners that are the outer peripheral areas of the part plate 11A, and a tension applying means that applies a tension to each tie bar 14 to generate a clamping force, are provided on the back surface of the fixed die plate 2. And four mold clamping hydraulic cylinders 15. One end of each tie bar 14 is inserted into each insertion hole 12 of the fixed die plate 2, and the other end side of each tie bar 14 passes through each notch step portion 13 of the movable die plate 4 and each insertion hole of the movable side end plate 11 </ b> A. 12 is inserted. One end of each tie bar 14 is coupled to a piston portion (not shown) of each mold clamping hydraulic cylinder 15, and the other end of each tie bar 14 is coupled to the movable side end plate 11A by a nut or the like (not shown). ing. In this way, each tie bar 14 is pulled toward the fixed die plate 2 by the operation of each mold clamping hydraulic cylinder 15, whereby tension is applied to each tie bar 14, and the fixed mold 3 and the movable mold 5 in the closed state are formed. The mold is clamped with a predetermined clamping force.

  Here, in the mold clamping device of this embodiment, in the longitudinal direction of the cavity 7, the length of the movable spacer member 10 </ b> A as the mold clamping force transmission portion is approximately the length of the cavity projection surface in the mold clamping direction. It is set to 92%.

  Specifically, the diameter (D, 1100 mm in the present embodiment) of the movable spacer member 10A is approximately 92 with respect to the longitudinal direction length (L, 1200 mm in the present embodiment) of the cavity projection surface in the mold clamping direction. The movable spacer member 10A is disposed so that the center of the movable spacer member 10A and the center of the cavity 7 in the longitudinal direction coincide with each other.

  In the mold clamping apparatus of the present embodiment having the above-described configuration, the movable side end plate 11A and the like move forward relative to the fixed die plate 2 by the operation of the moving hydraulic cylinder, and the fixed mold 3 and the movable mold 5 are closed. In this state, each of the mold clamping hydraulic cylinders 15 is operated, so that the fixed mold 3 and the movable mold 5 are clamped with a predetermined mold clamping force so as to withstand the pressure of the molten resin injected and filled into the cavity 7. Is done. At this time, in the movable die plate 4 in which the movable side end plate 11A is disposed on the back side, the movable die plate 4 is moved from the movable side end plate 11A through a movable side spacer member 10A as a mold clamping force transmitting portion. The clamping force acts on the.

  In the mold clamping device of the present embodiment, the length dimension of the movable spacer member 10A as the mold clamping force transmitting portion is set to about 92% of the length dimension of the cavity projection surface in the mold clamping direction. Therefore, with respect to the movable die plate 4 and the movable mold 5, the length in the longitudinal direction of the range in which the pressure in the cavity acts from the cavity projection surface in the mold clamping direction, and the mold from the movable side spacer member 10A as the mold clamping force transmitting portion. The relationship with the length in the longitudinal direction of the range in which the tightening force acts becomes appropriate, and as a result, the force that generates the distortion that causes the PL surface of the movable mold 5 to bulge outward in the central region in the longitudinal direction of the cavity 7, and the cavity 7 The balance between the PL surface of the movable mold 5 and the force that generates distortion that causes the PL surface to bend outward in both end regions in the longitudinal direction is well balanced, and the distortion generated on the PL surface of the movable mold 5 due to the pressure in the cavity is suppressed. be able to.

  Therefore, according to the mold clamping device of the present embodiment, it is possible to effectively suppress the occurrence of burrs in the PL portion of the thin long product 1 as a molded product. Therefore, a step of removing burrs by post-processing is not necessary, and, for example, when manufacturing a thin long resin molded product such as a side molding attached to the side surface of the vehicle, the manufacturing process can be simplified and the quality can be improved.

  Further, in the mold clamping device of the present embodiment, the mold clamping force generating means 6 is a tension applying means provided on each of the four tie bars 14 that connect the movable side end plate 11A and the fixed die plate 2. Since the mold clamping hydraulic cylinder 15 is provided and is a so-called double-acting type, the entire apparatus can be reduced in size as compared with the direct pressure type in which a large capacity hydraulic cylinder or the like must be used.

  Furthermore, in the mold clamping device of the present embodiment, the movable spacer member 10A as a mold clamping force transmitting portion is provided separately from the movable die plate 4 and the movable side end plate 11A, and is divided into three parts. Therefore, the transportability and handleability of the apparatus can be improved as compared with the case where the mold clamping force transmission portion is integrated with the die plate or the end plate.

(Evaluation test)
In the mold clamping apparatus of the above embodiment, the diameter (D) of the movable spacer member 10A and the plate thickness (T) of the movable die plate 4 are variously changed as shown in Table 1, and the strain on the PL surface of the movable mold 5 is changed. Evaluated. The ratio (D / L) of the diameter (D) of the movable spacer member 10A to the longitudinal length of the cavity 7 (L = 1200 mm), that is, the length of the cavity projection surface in the mold clamping direction in the longitudinal direction of the cavity 7 Table 1 also shows the ratio (D / L) of the length dimension (D) of the movable spacer member 10A as the mold clamping force transmission portion with respect to the length dimension (L = 1200 mm).

  As shown in the perspective view of the movable mold 5 divided into four parts in FIG. 4, this evaluation is performed by changing the horizontal position from the center of the apparatus in the longitudinal direction of the cavity 7 little by little while moving the movable mold 5 at each horizontal position. The measurement was performed by measuring the amount of displacement of the PL surface in the mold thickness direction (the horizontal direction in FIG. 1 and the direction parallel to the mold clamping direction). The results are shown in FIG.

  In FIG. 5, the point where the value of the horizontal position from the center is 0 mm indicates the center of the cavity 7 in the longitudinal direction, and the length of the cavity 7 increases as the value of the horizontal position from the center increases. Indicates approaching end of direction. No. The 200 mm spacer integrated structure shown in FIG. 1 is one in which the movable die plate 4 and the movable side end plate 11A are integrally provided, and indicates a conventional so-called double-acting mold clamping device. No. 6 is the mold clamping device of the embodiment described above.

  Further, the maximum displacement difference in Table 1 is the difference between the displacement amount at the measurement position where the displacement is maximum and the displacement amount at the measurement position where the displacement is the minimum. This indicates that the distortion is large.

  As is apparent from Table 1 and FIG. 5, D / L is 100%, that is, the length dimension of the movable spacer member 10A as the mold clamping force transmitting portion is equal to the length dimension of the cavity projection surface in the mold clamping direction. No. 7, in the longitudinal direction of the cavity 7, the displacement amount of the mold PL surface is larger in the central region than in the end region, and the mold PL surface is greatly distorted.

  On the other hand, D / L is 75 to 95%, that is, the ratio of the length dimension of the movable spacer member 10A to the length dimension of the cavity projection surface is 75 to 95%. 3 to 6, there was no significant difference in the displacement amount of the mold PL surface between the end region and the central region in the longitudinal direction of the cavity 7, and the distortion of the mold PL surface was suppressed. In particular, D.L with a D / L of about 92%. In No. 6, the maximum displacement difference was the smallest, and the distortion of the mold PL surface was further suppressed.

  In addition, when the D / L is less than 50%, the present inventor has a large displacement amount of the mold PL surface in the end region in the longitudinal direction of the cavity 7 compared to the central region, and the mold PL surface is greatly distorted. That is, when the D / L is 50%, the amount of displacement of the mold PL surface in the end region is smaller than when the D / L is less than 50%, and distortion of the mold PL surface is suppressed. I have confirmed.

  In addition, although D / L is 75%, the thickness (T) of the movable die plate 4 is as thin as 200 mm. 2, in the longitudinal direction of the cavity 7, the displacement amount of the mold PL surface is larger in the end region than in the central region, and the plate thickness (T) of the movable die plate 4 is 300 mm. The distortion of the mold PL surface was larger than 3. This is presumably because the movable die plate having a thin plate thickness and low rigidity was distorted by the clamping force.

  From these results, in the longitudinal direction of the cavity 7, the ratio (D) of the length dimension (D) of the movable spacer member 10 </ b> A as the mold clamping force transmitting portion to the length dimension (L) of the cavity projection surface in the mold clamping direction (D) / L) is 50% or more, there is an effect of suppressing the distortion of the mold PL surface, and when D / L is 75 to 95%, the distortion of the mold PL surface can be satisfactorily suppressed. It can be seen that if it is ˜92%, the distortion of the mold PL surface can be suppressed particularly well.

(Embodiment 2)
The mold clamping apparatus of the present embodiment shown in FIG. 6 is provided on the back surface of the fixed die plate 2 via a fixed-side spacer member 10B as a mold clamping force transmitting portion that transmits the mold clamping force to the fixed die plate plate 2. The fixed-side end plate 11B is disposed.

  The fixed side end plate 11B is fixed on the base. In addition, notch step portions 13 similar to the movable die plate 4 are provided at the four corners of the fixed die plate 2, and the fixed die plate 2 can move forward and backward with respect to the fixed side end plate 11B. It is arranged.

  The fixed spacer member 10B and the fixed end plate 11B are provided with a cavity 9 through which the injection nozzle 8 is inserted and accommodated.

  Other configurations of the fixed-side spacer member 10B and the fixed-side end plate 11B are the same as those of the movable-side spacer member 10A and the movable-side end plate 10B in the mold clamping device of the first embodiment.

  Therefore, according to this mold clamping apparatus, the distortion which generate | occur | produces in the PL surface of the fixed mold | type 3 by the pressure in a cavity can also be suppressed. Therefore, as compared with the mold clamping device of the first embodiment, it is possible to more effectively suppress the occurrence of burrs in the PL portion of the thin long product 1 as a molded product.

  Other configurations and operational effects are the same as those of the first embodiment.

(Other embodiments)
In the above-described embodiment, an example of a so-called double-acting type mold clamping device in which a mold clamping hydraulic cylinder is provided for each tie bar as the mold clamping force generating means has been described, but the present invention is limited to this. Instead, it may be a so-called direct pressure type mold clamping device that generates a mold clamping force with one mold clamping hydraulic cylinder.

  In the direct pressure type mold clamping device, the fixed die plate and the fixed mold are mainly distorted and deformed by the mold clamping force. For this reason, in the case of the direct pressure type, it is preferable to provide an end plate disposed via a mold clamping force transmitting portion on at least the back side of the fixed die plate of the fixed die plate and the movable die plate.

  Further, the example in which the mold clamping force transmission unit is provided separately from the die plate and the end plate has been described, but the mold clamping force transmission unit may be provided integrally with the die plate or the end plate.

  Furthermore, in the above-described embodiment, the application example in the case of forming a thin long product has been described. However, the present invention is not limited to this, and the present invention is applicable to the case of forming a circular product or a square product. It is possible to apply

It is a side view which shows typically the whole structure of the clamping device which concerns on Embodiment 1 of this invention. It is the fragmentary perspective view which divided the principal part of the mold clamping device which concerns on Embodiment 1 of this invention into 4 by the centerline O of the apparatus. It is a perspective view of the thin long product molded in Embodiment 1 of the present invention. It is a fragmentary perspective view of the movable type | mold 5 divided into 4 by the centerline of the apparatus shown in order to demonstrate the displacement measurement position and displacement direction at the time of evaluating the mold clamping apparatus which concerns on Embodiment 1 of this invention. It is a graph which shows the result of having evaluated the mold distortion of the mold clamping apparatus which concerns on Embodiment 1 of this invention, and the mold clamping apparatus of a comparative example. It is a side view which shows typically the whole structure of the clamping device which concerns on Embodiment 2 of this invention. Explanatory drawing schematically showing how the distortion of the mold PL surface changes depending on the relationship between the length dimension of the cavity projection surface in the mold clamping direction and the length dimension of the mold clamping force transmitting portion in the longitudinal direction of the cavity. It is. Explanatory drawing schematically showing how the distortion of the mold PL surface changes depending on the relationship between the length dimension of the cavity projection surface in the mold clamping direction and the length dimension of the mold clamping force transmitting portion in the longitudinal direction of the cavity. It is. Explanatory drawing schematically showing how the distortion of the mold PL surface changes depending on the relationship between the length dimension of the cavity projection surface in the mold clamping direction and the length dimension of the mold clamping force transmitting portion in the longitudinal direction of the cavity. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thin long product 2 ... Fixed die plate 3 ... Fixed mold 4 ... Movable die plate 5 ... Movable mold 6 ... Mold clamping force generation means 7 ... Cavity 10A ... Movable side spacer member (clamping force transmission part)
11A: Movable side end plate 10B: Fixed side spacer member (clamping force transmission part)
11B ... Fixed side end plate 14 ... Tie bar 15 ... Clamping hydraulic cylinder (tension applying means)

Claims (5)

A fixed die plate, a fixed die attached to the fixed die plate, a movable die plate disposed to be movable forward and backward with respect to the fixed die plate, and attached to the movable die plate with respect to the fixed die A movable mold that forms a cavity corresponding to the shape of the molded product between the fixed mold and the fixed mold, and a mold clamping force for clamping the fixed mold and the movable mold in a closed condition In a mold clamping device comprising a mold clamping force generating means for generating
At least one of the fixed die plate and the movable die plate disposed on the back side of at least one of the die plates via a mold clamping force transmitting portion that transmits a mold clamping force to the die plate. Having end plates,
In the longitudinal direction of the cavity, the mold clamping force transmitting portion is set to a length dimension that is shorter than the length dimension of the cavity projection plane in the mold clamping direction and 50% or more of the length dimension of the cavity projection plane. A mold clamping device characterized by that.   2. The mold clamping apparatus according to claim 1, wherein the mold clamping force transmission portion is set to a length dimension of 75 to 95% of a length dimension of the cavity projection surface.   The mold clamping force generating means connects the outer peripheral area of the end plate and the outer peripheral area of the fixed die plate or the movable die plate, or a plurality of tie bars connecting the outer peripheral areas of both the end plates. The mold clamping device according to claim 1, further comprising: a plurality of tension applying units that apply tension to each of the tie bars to generate the mold clamping force.   The mold clamping device according to claim 1, 2 or 3, wherein the mold clamping force transmission part is constituted by a spacer member provided separately from the die plate and the end plate.   5. The mold clamping device according to claim 1, wherein the molded product is a long molded product.

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