JP2006181736A - Injection mold and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an injection mold constituted so as to design the mold by estimating the bending quantity of a mold at the time of molding before the manufacture of the mold to reduce the bending of the mold at the time of molding by the fine adjustment of the arrangement of a shim and a gap without altering the mold itself after the completion of the mold. <P>SOLUTION: The estimate bending quantities of designed molds 13, 14 at the time of molding are analyzed at the time of designing of the molds, the arrangement of the shim 16 and the gap due to pressure receiving plates 17 between the attaching plate and the molds of an injection molding machine is temporarily determined to correct the design of the molds on the basis of the analyzing result, the estimate bending quantities of the corrected molds at the time of temporarily determined arrangement of the shim and the gap are again analyzed, second and third stages are repeated until the estimate bending quantities become a predetermined value or below to finally determine the arrangement of the shim and the gap to correct the design of the molds, the molds corresponding to the finally determined arrangement of the shim and the gap are manufactured and a molded product is actually molded by the manufactured molds to finely adjust the arrangement of the shim and the gap on reference to actually formed burr. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  According to the present invention, a fixed mold and a movable mold are opposed to each other and closed under a predetermined pressure, and a molten resin is filled at a high pressure into a cavity defined between the molds. The present invention relates to an injection mold and a manufacturing method thereof.

  Conventionally, in such an injection molding method, as shown in FIG. 5, the respective molds, that is, the fixed mold 1 and the movable mold 2 are arranged to face each other in the mold clamping portion of the injection molding machine. It is attached to a pair of attachment plates 3 and 4. Then, these molds are opposed to each other and closed (clamped) by a hydraulic cylinder 5 under a predetermined pressure of, for example, about 2000 to 4000 tons, and a cavity defined between these molds (see FIG. (Not shown) is filled with a molten resin at high pressure to perform injection molding of the molded product. In this case, it is necessary to clamp the molds 1 and 2 with a pressure equal to or higher than the pressure of the molten resin so that the molds 1 and 2 are not opened by the pressure of the molten resin filled in the cavity.

  However, as shown in FIG. 5, the pressure of the molten resin acts on the molds 1 and 2 as indicated by the arrow X, particularly near the center of the molds 1 and 2. The partition lines of the molds 1 and 2 are bent in the direction in which the partition lines of the molds 1 and 2 are opened, and the partition lines of the molds 1 and 2 are bent in the directions in which the partition lines of the molds 1 and 2 are closed. 6 may occur. Such bending of the mold is considered to be caused by, for example, the mold structure, mold thickness, mold material, mold clamping machine structure, resin pressure receiving area, and the like.

  Further, as shown in FIG. 6, a pressure receiving plate 7 is disposed on the pressure receiving surfaces 1a and 2a provided at the peripheral portions of the molds 1 and 2 so as to seal between them. Further, the pressure receiving surfaces 1a and 2a come into contact with each other when the molds 1 and 2 are bent in the directions in which they are closed at the four corners. Therefore, such a contact promotes the generation of the gap 6 near the center of the molds 1 and 2 described above.

  Since the mold is not designed in consideration of the bending during the mold clamping, when the molded product is molded, the molten resin enters the gap 6 generated between the molds 1 and 2. As a result, burrs are generated.

  Conventionally, as a countermeasure against the occurrence of burrs, since the so-called try-and-error is performed while the molded product is actually formed after the mold is completed, the generation of burrs cannot be easily suppressed. It takes a lot of man-hours and time.

On the other hand, Patent Document 1 discloses an RTM molding method in which a shim for adjusting the surface pressure of an elastic seal for preventing resin leakage is disposed. Patent Document 2 discloses a molding machine in which a shim is disposed between an attachment member (mother mold) and a mold, and the contact surface of the mold is adjusted by adjusting the thickness of the shim. Is disclosed.
Japanese Patent Application Laid-Open No. 07-060765 JP 09-150421 A

  However, in the RTM molding method according to Patent Document 1, a shim is disposed in order to adjust the surface pressure of the elastic seal for preventing resin leakage, and does not prevent generation of burrs due to bending of the mold.

  Moreover, in the molding machine by patent document 2, by adjusting the thickness of a shim, by adjusting the contact surface of a metal mold | die, the clearance gap between metal mold | dies is eliminated, and generation | occurrence | production of a burr | flash is prevented. However, shim adjustment is performed by trial-and-error while the molded product is actually formed after the mold is manufactured. At that time, the shim is adjusted by adjusting the location, size, and thickness, for example. Therefore, it takes time to find the optimum adjustment, and it may be necessary to remanufacture the mold as well. It will take a lot of man-hours and time.

  In view of the above points, the present invention predicts the amount of bending of a mold during injection molding before manufacturing the mold and designs the mold to change the mold itself after completion of the mold. An object of the present invention is to provide an injection mold and a method for manufacturing the same, in which bending of the mold during injection molding is reduced by finely adjusting the arrangement of shims and gaps.

  In order to achieve the above-mentioned object, according to the present invention, a mold composed of a fixed mold and a movable mold is attached to a pair of mounting plates arranged opposite to each other in a mold clamping part of an injection molding machine. These molds are opposed to each other and closed under a predetermined pressure, and a molded product is injection-molded by filling the cavity defined between the molds with molten resin at a high pressure. In the manufacturing method of the injection mold, the first stage of analyzing the predicted deflection amount at the time of molding of the designed mold, and the injection molding based on the analysis result of the predicted deflection amount The second stage of correcting the design of the mold by temporarily determining the arrangement of the shim between the mounting plate of the machine and the mold and the gap provided on the pressure receiving surface outside the mold, and the tentatively determined shim and gap Analyze the predicted deflection of the correction mold when placing The third stage and the second and third stages are repeated until the predicted amount of deflection of the mold, that is, the mold opening amount is equal to or less than a predetermined value, and the arrangement of the shim and the gap is finally determined to design the mold. A fourth stage of correcting the above, a fifth stage of manufacturing a mold corresponding to the determined arrangement of the shim and the gap, and actually forming a molded product by the manufactured mold. And a sixth stage for finely adjusting the arrangement of the shim and the gap with reference to the burr.

  In the method of manufacturing an injection mold according to the present invention, preferably, in the sixth stage, the thickness of the shim disposed near the center of the contact area between the injection molding machine and the mold is adjusted. To finely adjust the gap in the mold opening direction.

  The method for manufacturing an injection mold according to the present invention preferably comprises, in the sixth stage, adjusting the thickness of the pressure receiving plates disposed on the pressure receiving surfaces facing each other between the molds, thereby opening the mold. Fine-tune the gap in the direction perpendicular to the direction.

  In order to achieve the other object, according to the second configuration of the present invention, a fixed mold and a movable mold respectively attached to a pair of mounting plates arranged opposite to each other in a mold clamping part of an injection molding machine. The mold is composed of molds, and in a state where these molds are opposed to each other and closed under a predetermined pressure, a cavity defined between these molds is filled with molten resin at a high pressure. In an injection mold for injection molding of a molded product, a shim and a gap provided on a pressure receiving surface outside the mold are disposed between a mounting plate of the injection molding machine and the mold. And the gap is arranged based on the predicted deflection amount at the time of molding the mold at the time of mold design so that the predicted deflection amount is not more than a predetermined value, and the thickness of the shim is selected. To do.

  According to the above configuration, before the mold production, analyze the predicted deflection amount of the mold due to the mold clamping force and the resin pressure in the mold at the time of injection molding, and refer to the analysis result of this predicted deflection amount, By designing the mold by temporarily determining the arrangement of shims and gaps, the predicted deflection of the mold can be made to be a predetermined value or less. Then, after manufacturing a mold designed by incorporating the analysis result of the predicted deflection amount, the molded product is actually molded using this mold, and the burrs that are actually generated are referred to. Final adjustment of shim and gap placement due to errors.

  In this case, since the mold is designed in consideration of the predicted amount of deflection at the time of injection molding, adjustment of shims and gaps by trial and error is fine adjustment. There is no need to change the mold thickness or mold structure, that is, re-manufacture of the mold. Accordingly, since the optimum mold can be manufactured easily and in a short time, the cost of mold manufacture can be reduced, the delivery time of the mold can be shortened, and the cost of the molded product can be reduced.

  When finely adjusting the gap in the mold opening direction by adjusting the thickness of the shim disposed in the vicinity of the center of the contact area between the injection molding machine and the mold in the sixth stage, By adjusting the thickness of the shim in response to the bending in the opening direction near the center of the mold due to the mold clamping force and the resin pressure in the mold during injection molding, the gap near the center due to the bending of the mold is reduced. Thus, the generation of burrs can be suppressed.

  In the sixth stage, the gap in the direction perpendicular to the mold opening direction is finely adjusted by adjusting the thickness of the pressure receiving plates disposed on the pressure receiving surfaces facing each other between the molds. In this case, by adjusting the thickness of the pressure receiving plate corresponding to the bending in the above direction near the outer edge of the mold due to the clamping pressure, the gap near the outer edge due to the bending of the mold is reduced, and burrs are generated. Can be suppressed.

  As described above, according to the present invention, the completed mold is considered for the predicted deflection amount due to the clamping force and the resin pressure in the mold at the time of injection molding.・ When adjusting shims and gaps while molding a molded product with AND error, there is no need to adjust the mold thickness or mold structure to change the thickness of the shim or pressure receiving plate. It is possible to optimally reduce the bending of the mold during injection molding only by fine adjustment of the gap by changing the thickness of the mold. Therefore, it is not necessary to remanufacture the mold, and the man-hours until completion of the mold can be reduced, the mold manufacturing time is greatly reduced, and the cost of the molded product is also greatly reduced.

The present invention will be described in detail below based on the embodiments shown in the drawings.
1 and 2 show an injection molding apparatus used in an embodiment of an injection mold according to the present invention. 1 and 2, an injection molding apparatus 10 includes a fixed mold 13 and a movable mold that are respectively attached to opposing surfaces of a pair of mounting plates 11 and 12 that are arranged to face each other in a mold clamping portion of an injection molding machine. A shim 16 inserted between a mold 14, a hydraulic cylinder 15 that presses these mounting plates 11 and 12 to face each other, and a mold, in the illustrated case, a fixed mold 13 and the corresponding mounting plate 11. And a pressure receiving plate 17 provided on the pressure receiving surface outside the mold. The mounting plates 11 and 12, the hydraulic cylinder 15 and the injection molding machine are configured in the same manner as in the prior art.

  In accordance with the present invention, the molds 13 and 14 are analyzed for the amount of bending caused by the clamping force and the resin pressure in the mold at the time of injection molding at the time of designing before manufacture, so as to reduce the predicted amount of bending analyzed. It is designed and manufactured in consideration of the arrangement of the gap provided on the pressure receiving surface outside the shim and the mold. More specifically, a shim 16 having a predetermined thickness is disposed between the mold 13 and the mounting plate 11 so as to reduce bending in the opening direction at the time of molding near the center of the molds 13 and 14. In addition, a pressure receiving plate 17 having a predetermined thickness provided on the pressure receiving surface between the mold 13 and the mold 14 is disposed so as to reduce bending in the closing direction at the time of molding at the outer edge, particularly at the four corners. The molds 13 and 14 are designed so as to reduce the predicted deflection amount of the molds 13 and 14.

  When designing the molds 13 and 14, the shim 16 has the position, size and thickness of the molds 13 and 14, the mounting plates 11 and 12 of the injection molding machine, and if necessary, a pressure receiving plate 17 which will be described later. Is temporarily determined to analyze the predicted deflection amount of the molds 13 and 14 at the time of molding to reduce the predicted deflection amount.

  Further, the shim 16 is used to reduce the amount of bending of the molds 13 and 14 by the so-called try-and-error method by actually molding the molded product after the molds 13 and 14 are completed. The position, size, and thickness are finely adjusted as appropriate.

  In this case, since the molds 13 and 14 are manufactured with reference to the predicted deflection amount analyzed at the design stage, the optimization of the deflection amount of the molds 13 and 14 by adjusting the shim 16 can be made by fine adjustment. In other words, it is possible to avoid remanufacturing the mold as in the prior art.

  The pressure receiving plate 17 is interposed between the pressure receiving surfaces 13a and 14a where the molds 13 and 14 come into contact with each other in the vicinity of the outer edges of the molds 13 and 14, and between the pressure receiving surfaces 13a and 14a. The defined gap is appropriately filled. Here, since the pressure receiving plate 17 is manufactured with reference to the predicted deflection amount analyzed in the design stage of the molds 13 and 14, the adjustment of the gap between the pressure receiving surfaces 13a and 14a is the same. Fine adjustment is required, and adjustment is made simply by changing the thickness of the pressure receiving plate 17.

  The injection molding apparatus 10 using the injection mold according to the embodiment of the present invention is configured as described above. The operations from the production of the injection mold to the injection molding are as follows according to the flowchart of FIG. Is implemented as follows.

  In FIG. 3, first, in step ST1, as a first stage of the method for manufacturing an injection mold, the molds 13 and 14 are molded by mold clamping force and resin pressure in the mold at the time of mold design. Analyze the predicted deflection. The analysis of the predicted deflection amount is performed by, for example, CAE (Computer Aided Engineering).

  Subsequently, in step ST2, as a second stage of the method of manufacturing the injection mold, the shim and the mold between the mounting plate of the injection molding machine and the mold based on the analysis result of the predicted deflection amount described above. Examine the layout of the gap provided on the outer pressure-receiving surface, and tentatively decide to correct the mold design. In this case, the predicted deflection amount of the molds 13 and 14 is selected as much as possible by appropriately selecting the position, size, and thickness of the shim and appropriately selecting the position and size of the gap by adjusting the thickness of the pressure receiving plate. The arrangement of shims and gaps is provisionally determined so as to be small.

  Next, in step ST3, as the third stage of the method for manufacturing the injection mold, the predicted deflection amount of the correction mold when the temporarily determined shims and gaps are arranged is analyzed again. Here, by reanalyzing the predicted deflection amount of the mold, a change in the predicted deflection amount due to the arrangement of the shim and the gap can be confirmed.

  Then, in step ST4, it is determined whether or not the predicted deflection amount (die opening amount) of the mold is equal to or less than a predetermined value. If it exceeds the predetermined value, the process returns to step ST2.

  On the other hand, if it is equal to or less than the predetermined value in step ST4, in step ST5, as the fourth stage of the manufacturing method of the injection mold, the arrangement of shims and gaps is determined and the mold Modify the design. This completes the mold design.

  Here, FIG. 4 is a flowchart showing in more detail the process from the time of designing the molds 13 and 14 (steps ST1 to ST5), that is, the mold design study work corresponding to the predicted deflection amount. The design study work examples 13 and 14 will be described in detail.

  In FIG. 4, first, in step ST11, in the initial design of the mold, the predicted deflection amount of the molds 13 and 14 at the time of molding, that is, the mold 13 by the mold clamping force and the resin pressure in the mold at the time of injection molding. The predicted deflection amount of 14 is predicted by CAE, and then the predicted deflection amount (die opening amount) is confirmed in step ST12. Here, if the mold opening amount is equal to or smaller than the predetermined value, that is, it is OK, the design study of the mold corresponding to the predicted deflection amount is finished in step ST13.

  On the other hand, if the mold opening amount exceeds a predetermined value, that is, NG, in step ST14, the bending or deformation shape of the molds 13 and 14 is determined based on the analysis result of the predicted bending amount described above. After confirming and examining, the layout of the shim between the mounting plate of the injection molding machine and the mold is provisionally determined, and the mold design is corrected.

  Next, in step ST15, the predicted deflection amount of the correction mold is calculated again under the condition where the temporarily determined shim is arranged. At this time, if necessary, several positions and thicknesses of shims are set, and calculation is performed for each combination. In step ST16, the predicted bending amount (die opening amount) of the mold is confirmed with respect to the clamping direction (see FIG. 1). Here, in the case of NG, the process returns to step ST14.

  In the case of OK, in step ST17, the predicted bending amount (die opening amount) of the mold is confirmed with respect to a direction perpendicular to the clamping direction (see FIG. 1). If the result is OK in step ST17, the design study of the mold corresponding to the predicted deflection amount is completed in step ST18.

  On the other hand, in the case of NG in step ST17, in step ST19, based on the above-described analysis result of the predicted deflection amount, the bending, that is, the deformed shape of the molds 13, 14 is confirmed and examined, Temporarily determine the position of the pressure-receiving plate and the gap between the outer edges of the mold, and modify the mold design.

  Next, in step ST20, the predicted deflection amount of the correction mold is calculated again under the condition that the pressure receiving plate and the gap that are provisionally determined are arranged. At this time, if necessary, several thicknesses and gaps of the pressure receiving plate are set, and calculation is performed for each combination. In step ST21, the predicted bending amount (die opening amount) of the mold is confirmed with respect to the direction perpendicular to the clamping direction. Here, in the case of NG, the process returns to step ST19.

  In the case of OK, in step ST22, the predicted deflection amount of the correction mold is calculated again under the condition in which the shim, the pressure receiving plate, and the gap between them are arranged. In this case as well, calculation is performed for each combination by setting several pressure receiving plate thicknesses, such as shim size and thickness, and gaps as necessary.

Finally, in step ST23, the predicted deflection amount (die opening amount) of the mold is confirmed in a direction perpendicular to the mold clamping direction. Here, in the case of NG, the process returns to step ST22. In the case of OK, in step ST24, the mold design study corresponding to the predicted deflection amount is completed.
This completes the mold design.

  After completion of the above-described mold design review work, in step ST6 shown in FIG. 3, as a fifth stage of the injection mold manufacturing method, the mold corresponding to the determined arrangement of the shim and the gap is determined. Is produced.

  Next, in step ST7 of FIG. 3, the molds 13 and 14 manufactured in this way are used, the determined shims and gaps are arranged, and the molds 13 and 14 are mounted on the injection molding machine. According to this, the molded product is actually molded.

  In step ST8, the burr actually generated in the molded product is referred to, and the arrangement of shims and gaps is finely adjusted by so-called try-and-error (sixth stage).

  In this case, as described above, when the molds 13 and 14 are designed, the predicted bending amount of the molds 13 and 14 due to the clamping force at the time of molding and the resin pressure in the mold is analyzed, and the analysis result is obtained. Since the mold is modified by weaving, the amount of bending of the molds 13 and 14 at the time of actual molding is very small, and it can be adjusted sufficiently by fine adjustment of shims and gaps. It is settled.

  Therefore, after performing the test molding of the actual molded product, in order to reduce the amount of bending of the mold due to the mold clamping force and the resin pressure in the mold, the mold thickness and mold structure change, That is, it is not necessary to remanufacture the mold.

  In this way, by using an injection mold adjusted by so-called try-and-error, a molded product can be molded by an injection molding machine. In this case, from the first molding after completion of the mold, it is possible to reduce the amount of bending of the mold at the time of injection molding and perform molding without generation of burrs. Therefore, the molding cost is reduced and the productivity of the molded product is improved.

  As described above, according to the method for manufacturing an injection mold according to the embodiment of the present invention, the mold is designed by predicting the bending amount of the mold at the time of molding before the mold is manufactured. After completion, to produce a very good injection mold that reduces the bending of the mold during molding by finely adjusting the arrangement of shims and gaps without changing the mold itself Can do.

  Although the present invention has been described in detail above, the present invention can be implemented in various forms without departing from the spirit of the invention. For example, in the above-described embodiment, the case where the shim 16 is disposed between the fixed mold 13 and the mounting plate 11 has been described. However, the present invention is not limited thereto, and the shim is interposed between the movable mold 14 and the mounting plate 12. Similarly, the present invention can also be applied to the case of arranging.

  Further, in the above-described embodiment, the shim 16 is disposed and the thickness of the pressure receiving plate 17 is adjusted to adjust the thickness of the gap defined therebetween. Only one adjustment may be sufficient.

It is a schematic sectional drawing of the injection molding apparatus which uses the metal mold | die for injection molding of this invention. It is an AA line sectional view in the injection molding device of FIG. It is a flowchart which shows in order the manufacturing method of the injection mold by the injection molding apparatus of FIG. It is a flowchart which shows the design examination work of the metal mold | die in the manufacturing method of the injection mold of FIG. It is a schematic sectional drawing of the injection molding apparatus used with the conventional injection molding method. It is the sectional view on the AA line in the injection molding apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Injection molding apparatus 11, 12 Mounting plate of mold clamping part 13 Fixed mold 14 Movable mold 15 Hydraulic cylinder 16 Shim 17 Pressure receiving plate

Claims (4)

A mold composed of a fixed mold and a movable mold is attached to a pair of mounting plates arranged opposite to each other in a mold clamping portion of an injection molding machine, and these molds are opposed to each other under a predetermined pressure. In a method for manufacturing an injection mold, the mold is closed and filled with molten resin at a high pressure in a cavity defined between the molds.
At the time of the mold design, a first stage of analyzing the predicted deflection amount at the time of molding the designed mold,
Based on the analysis result of the predicted amount of deflection, the layout of the shim between the mounting plate of the injection molding machine and the mold and the arrangement of the gap provided on the pressure receiving surface outside the mold are provisionally determined, and the mold design is corrected. The second stage to do,
A third stage for analyzing again the predicted deflection amount of the correction mold when the temporarily determined shims and gaps are disposed;
Repeating the second and third steps until the predicted amount of deflection of the mold is less than or equal to a predetermined value, and finally determining the arrangement of the shims and gaps and correcting the mold design; ,
A fifth stage for producing a mold corresponding to the determined shim and gap arrangement;
A sixth stage in which the molded product is actually molded by the manufactured mold, and the arrangement of the shim and the gap is finely adjusted with reference to the burr actually generated;
The manufacturing method of the metal mold | die for injection molding characterized by including.   In the sixth stage, the gap in the mold opening direction is finely adjusted by adjusting the thickness of the shim disposed near the center of the contact area between the injection molding machine and the mold. The method for producing an injection mold according to claim 1.   In the sixth step, the gap in the direction perpendicular to the mold opening direction is finely adjusted by adjusting the thickness of the pressure receiving plates disposed on the pressure receiving surfaces facing each other between the molds. The method for producing an injection mold according to claim 1 or 2. It consists of a fixed mold and a movable mold that are respectively attached to a pair of mounting plates arranged opposite to each other in the mold clamping part of the injection molding machine, and these molds are opposed to each other and closed under a predetermined pressure. In an injection mold in which a molded product is injection-molded by filling a molten resin at a high pressure in a cavity defined between these molds in a state where
Between the mounting plate of the injection molding machine and the mold, a gap provided on the pressure receiving surface of the shim and the mold is disposed,
These shims and gaps are arranged so that the predicted deflection amount is equal to or less than a predetermined value based on the predicted deflection amount at the time of molding the mold at the time of mold design, and the thickness of the shim is selected. An injection mold characterized by the above.

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