JP2008201016A - Injection molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an optimum injection molding method capable of meeting the need of energy saving, and to contribute to improvement of quality of molding, improvement of yield, long life of a mechanism part, ensuring of quality and improvement of maintenance properties. <P>SOLUTION: A mold thickness adjusting mechanism 4 is set in advance at a position (mold gap setting position Xs) capable of obtaining a specified gap G (set mold gap Ls) between a fixed mold 1c and a movable mold 1 m with no leakage of a molten resin during injection molding under a condition that a toggle link mechanism 2 is locked up. During injection molding, the mold is opened by shortening the toggle link mechanism 2, and the mold is closed by locking up the toggle link mechanism 2, and under this closed mold condition, at least an injection process (S4) and a cooling process (S6) are performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an injection molding method for performing injection molding by injecting and filling molten resin from an injection device into a mold having a fixed mold and a movable mold supported by a mold opening / closing device.

  Conventionally, as an injection molding machine, particularly an injection molding machine provided with a toggle link type clamping device, an injection molding machine disclosed in Japanese Patent Publication No. 6-61806 and Japanese Patent Application Laid-Open No. 2005-138447 is known. .

By the way, in the injection molding method by the injection molding machine, the molten resin is usually injected and filled from the injection device to the mold, so that the molten resin does not leak out of the mold so to speak to the mold. Clamping with pressure is performed, and the mold clamping force F in this case is set by F ≧ Ac × Pc (Ac: projected area, Pc: in-mold average pressure). In particular, the toggle link type mold clamping device uses a toggle link mechanism to connect the movable plate supporting the movable die and the crosshead that is advanced and retracted by the drive unit, and increases the pressure applied to the crosshead and transmits it to the movable platen. The toggle link mechanism has a function of generating a predetermined clamping force based on the extension of the tie bar when the toggle link mechanism is almost extended. In the mold clamping operation, the high-speed mold closing is normally performed from the mold opening position, and the process shifts to the low-speed / low-pressure mold closing when the preset low-speed / low-pressure switching position is reached. This low-speed and low-pressure mold closing becomes a mold protection section, and a molded article or the like that has not been normally discharged is detected as a foreign object. Thereafter, when a preset high-pressure switching position (or a mold closing position detected based on the operation physical quantity) is reached, the process proceeds to high-pressure clamping and high-pressure clamping is performed.
JP 6-61806 JP 2005-138447 A

  However, the conventional injection molding method in the above-described injection molding machine has the following problems to be solved.

  In other words, in a normal injection molding method excluding molding methods that are basically different in molding principle, such as injection compression molding, as mentioned above, it is a common sense molding to apply pressure to the mold and perform clamping. It is law. One reason for this is that mold clamping has a side that compensates for the surface accuracy (quality) of the mold. If there is an uneven surface that deteriorates surface accuracy on the parting surface of the mold (fixed mold and movable mold), not only will molding defects such as burrs be caused, but it will also be a factor in reducing molding quality. Since the uneven surface can be reduced or eliminated by tightening, the poor surface accuracy of the mold can be compensated.

  On the other hand, in recent years, the processing precision (processing machine) for manufacturing molds has dramatically increased, and the precision of mold processing has increased dramatically, and the necessity (importance) for mold clamping due to internal factors has decreased. At the same time, there is a demand for energy saving due to external factors, that is, energy saving of industrial machinery is required from the viewpoint of global environment protection such as reduction of carbon dioxide emissions and resource saving. Sufficient measures against such a request, especially the fundamental measures including the departure from the above-mentioned common sense molding method have not been taken, and the optimum (ideal) that can meet such a request after all. The fact is that no injection molding method has been proposed.

  An object of the present invention is to provide an injection molding method that solves the problems existing in the background art.

  The injection molding method according to the present invention includes a fixed mold 1c and a movable mold supported by a mold opening / closing device Mc having a mold opening / closing mechanism 3 having a toggle link mechanism 2 for opening / closing the mold and a mold thickness adjusting mechanism 4 for adjusting the mold thickness. When injection molding is performed by injecting and filling molten resin from the injection device Mi into the mold 1 having 1 m, the mold thickness adjusting mechanism 4 is previously melted during injection molding with the toggle link mechanism 2 locked up. Is set at a position (die interval setting position Xs) for obtaining a predetermined gap G (set die interval Ls) between the fixed die 1c and the movable die 1m that does not leak, and the die is shortened by the toggle link mechanism 2 at the time of injection molding. The mold is closed by opening up and the toggle link mechanism 2 is locked up, and at least the injection process (S4) and the cooling process (S6) are performed in the closed state. That.

  In this case, according to a preferred aspect of the invention, the set die interval Ls can be set in the range of 0.001 to 0.1 [mm], and the gap G between the fixed die 1c and the movable die 1m (actual die interval Ld ) Can be detected by using the distance detector 5 attached to the fixed mold 1c and / or the movable mold 1m. On the other hand, by controlling the mold thickness adjustment mechanism 4 in advance, the movable mold 1m is moved forward from the mold opening position while the toggle link mechanism 2 is locked up, and the fluctuation of the operation physical quantity accompanying this forward movement is monitored. At the same time, the position where the operation physical quantity has reached the preset threshold value Ts is obtained as the mold closing position Xf, and thereafter, the mold thickness adjusting mechanism 4 obtains the set mold interval Ls with reference to the mold closing position Xf. It can be set to the mold interval setting position Xs. Note that the operating physical quantity can include a fluctuation rate (variation quantity) ΔT of the operating physical quantity. Further, at the time of injection molding, after the mold is closed by locking up the toggle link mechanism 2, the actual mold interval Ld between the fixed mold 1 c and the movable mold 1 m is detected, or from the injection device Mi for the mold 1. After the injection filling of the molten resin is completed, the actual mold interval Ld between the fixed mold 1c and the movable mold 1m is detected, and correction processing can be performed so that the detected mold interval Ld becomes the set mold interval Ls.

  According to the injection molding method according to the present invention using such a technique, the following remarkable effects can be obtained.

  (1) The mold thickness adjusting mechanism 4 obtains a predetermined gap G (set mold interval Ls) between the fixed mold 1c and the movable mold 1m that does not leak molten resin during injection molding with the toggle link mechanism 2 locked up. Since the mold interval setting position Xs is set and the toggle link mechanism 2 is locked up to perform the injection process (S4) and the cooling process (S6), the substantial mold clamping force on the mold 1 during injection filling is reduced. It becomes almost unnecessary, and it is possible to realize an optimal (ideal) injection molding method that can meet the demand for energy saving from the viewpoint of global environmental protection such as reduction of carbon dioxide emissions and resource saving.

  (2) At the time of injection molding, the toggle link mechanism 2 is locked up so that the molten resin is injected and filled into the mold 1 having the set mold interval Ls between the fixed mold 1c and the movable mold 1m. It is possible to reliably and stably vent the gas in the mold 1 at the time, thereby contributing to improvement in molding quality and yield.

  (3) Since a problem that unnecessary and large stress (clamping force) is applied to the mold 1 and the mold opening / closing device Mc can be avoided, the deterioration and failure of the mold 1 and the mold opening / closing device Mc are suppressed, and the mechanism This can contribute to longer life of parts, ensuring accuracy and improving maintainability.

  (4) If the set mold interval Ls is set in the range of 0.001 to 0.1 [mm] according to a preferred embodiment, both the degassing function and the molten resin leakage preventing function can be satisfactorily realized.

  (5) According to a preferred embodiment, the gap G (actual mold interval Ld) between the fixed mold 1c and the movable mold 1m is detected using the distance detector 5 attached to the fixed mold 1c and / or the movable mold 1m. By doing so, since the mold interval Ld can be directly detected, it is possible to detect an accurate mold interval Ld excluding error factors other than the distance detector 5.

  (6) According to a preferred embodiment, the mold thickness adjusting mechanism 4 is driven and controlled, whereby the movable mold 1m is moved forward from the mold opening position while the toggle link mechanism 2 is locked up, and the operation physical quantity accompanying this forward movement If the position where the operation physical quantity has reached the preset threshold value Ts is obtained as the mold closing position Xf, the mold thickness adjusting mechanism 4 can be used as a mold with reference to the mold closing position Xf. The interval setting position Xs can be set (adjusted) accurately and easily.

  (7) According to a preferred embodiment, if the movement physical quantity includes the fluctuation rate (fluctuation quantity) ΔT of the movement physical quantity, it is more accurate and stable than the case where the physical quantity itself (absolute value) is detected by comparison with the threshold value. Detection can be performed. That is, the method of detecting the physical quantity itself by comparing it with the threshold value is directly affected by disturbances such as temperature drift and mechanical friction, and cannot perform accurate and stable detection, but the fluctuation rate (variation quantity) of the operating physical quantity. By using ΔT, such a problem can be avoided.

  (8) According to a preferred embodiment, at the time of injection molding, after the mold is closed by locking up the toggle link mechanism 2, the actual mold interval Ld is detected, and the detected mold interval Ld becomes the set mold interval Ls. If the correction processing is performed, it is possible to always ensure an accurate set mold interval Ls, contribute to further improvement in molding quality and yield, and in particular, an actual mold interval Ld before injection filling can be obtained. Only the error factor can be corrected.

  (9) According to a preferred embodiment, at the time of injection molding, the actual mold interval Ld is detected after the injection filling of the molten resin from the injection device Mi to the mold 1 is completed, and the detected mold interval Ld is the set mold interval Ls. If the correction process is performed as described above, it is possible to always ensure an accurate set mold interval Ls, contribute to further improvement in molding quality and yield, and in particular, an actual mold interval Ld after injection filling can be obtained. The overall influence at the time of molding can be corrected.

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the configuration of the mold opening / closing device Mc used for carrying out the injection molding method according to the present embodiment will be described with reference to FIGS. 3 and 4.

  FIG. 3 shows an injection molding machine M, which includes a toggle link type mold opening / closing device Mc and an injection device Mi. The mold opening / closing device Mc includes a fixed platen 11 and a drive plate 12 that are spaced apart from each other. The fixed platen 11 is fixed on a machine base (not shown), and the drive board 12 can be moved back and forth on the machine base. Supported. Further, four tie bars 13 are installed between the fixed platen 11 and the drive platen 12. In this case, the front ends of the tie bars 13 are fixed to the stationary platen 11, and the rear ends of the tie bars 13 are inserted into the drive plate 12 and screw portions 14 formed on the rear end side. The adjustment nuts 15 that also serve as stoppers for the drive panel 12 are screwed together.

  Each adjustment nut 15 constitutes a mold thickness adjusting mechanism 4 that adjusts the position of the drive panel 12. The mold thickness adjusting mechanism 4 further includes small gears 17 provided coaxially with the adjusting nuts 15, a large gear 18 meshed with the small gears 17, and meshed with the large gear 18. And a mold thickness adjusting motor 20 provided with the drive gear 19 on the rotating shaft, and a rotary encoder 20e for detecting the rotational speed of the mold thickness adjusting motor 20.

  In this case, the small gears 17 are arranged at the four corners of the square, and the large gears 18 are arranged at positions surrounded by the small gears 17. Mesh. Accordingly, when the mold thickness adjusting motor 20 is operated, the rotation of the drive gear 19 is transmitted to the large gear 18, and the small gears 17 are rotated simultaneously, and the adjusting nuts 15 that rotate integrally are Since it moves forward and backward along the screw parts 14 of the tie bars 13..., The drive panel 12 can also move forward and backward, and its front-rear direction position can be adjusted.

  On the other hand, the movable platen 21 is slidably loaded on the tie bars 13. The movable platen 21 supports the movable die 1m, the fixed platen 11 supports the fixed die 1c, and the movable die 1m and the fixed die 1c constitute the mold 1. Further, the mold 1 is provided with a distance detector 5 for detecting a gap G between the fixed mold 1c and the movable mold 1m. The distance detector 5 includes four sensor portions 5p, and each sensor portion 5p is attached to four side surfaces (upper and lower surfaces and left and right surfaces) of the mold 1 (movable mold 1m and fixed mold 1c).

  FIG. 4 shows one sensor unit 5 p disposed on the upper surface of the mold 1. The sensor unit 5p is mounted on the upper surface of the movable mold 1m, so that the detected plate 5pr stands upright from the upper surface, and the proximity sensor disposed on the upper surface of the fixed mold 1c so as to face the detected plate 5pr. 5ps is provided. Thus, since the actual mold interval Ld can be detected directly by using the distance detector 5 attached to the fixed mold 1c and the movable mold 1m constituting the mold 1, error factors other than the distance detector 5 are eliminated. There is an advantage that an accurate mold interval Ld can be detected. In addition, if a part of movable mold | type 1m is utilized as a to-be-detected plate, the example to-be-detected plate 5pr is omissible.

  On the other hand, the toggle link mechanism 2 is disposed between the drive panel 12 and the movable panel 21. The toggle link mechanism 2 includes a pair of first links 2a and 2a that are pivotally supported on the drive board 12, a pair of output links 2c and 2c that are pivotally supported on the movable board 21, and the first links 2a and 2a and the output link 2c, A pair of second links 2 b and 2 b coupled to the support shaft of 2 c are provided, and the second links 2 b and 2 b are pivotally supported on the cross head 22.

  Further, a mold opening / closing drive unit 23 is disposed between the drive panel 12 and the cross head 22. The mold opening / closing drive unit 23 includes a ball screw unit 25 that is rotatably supported by the drive panel 12, and a ball nut unit 26 that is screwed into the ball screw unit 25 and provided integrally with the cross head 22. A ball screw mechanism 24 is provided, and a rotation drive mechanism unit 27 that rotationally drives the ball screw unit 25 is provided. The rotation drive mechanism 27 includes a mold opening / closing servo motor 28, a rotary encoder 28e attached to the servo motor 28 for detecting the rotation speed of the servo motor 28, and a drive gear 29 attached to the shaft of the servo motor 28. A driven gear 30 attached to the ball screw portion 25 and a timing belt 31 laid between the drive gear 29 and the driven gear 30 are provided.

  As a result, when the servo motor 28 is operated, the drive gear 29 rotates, and the rotation of the drive gear 29 is transmitted to the driven gear 30 via the timing belt 31, and the ball screw portion 25 rotates to thereby rotate the ball nut. The part 26 moves back and forth. As a result, the cross head 22 integrated with the ball nut portion 26 moves forward and backward, the toggle link mechanism 2 shortens or expands, and the movable platen 21 moves forward and backward in the mold opening direction (retracting direction) or the mold closing direction (forward movement direction). Moving. Reference numeral 40 denotes a molding machine controller, to which a mold opening / closing servomotor 28, a rotary encoder 28e, a mold thickness adjusting motor 20, a rotary encoder 20e, and four proximity sensors 5ps are connected. The toggle link mechanism 2 and the mold opening / closing drive unit 23 constitute a mold opening / closing mechanism 3.

  Next, the injection molding method according to the present embodiment including the operation (function) of the mold opening and closing device Mc configured as described above will be described according to the flowcharts shown in FIGS. 1 and 2 with reference to FIGS. .

  First, a mold interval setting preparation process is performed before performing the molding process (FIG. 1: step SR). A processing procedure of this mold interval setting preparation step is shown in FIG. First, the movable mold 1m is opened (step S21). This mold open state does not indicate a specific position, but may be a position where a certain amount of clearance can be secured between the movable mold 1m and the fixed mold 1c in a state where the toggle link mechanism 2 is locked up (extended). Therefore, it may be the last retracted position or any set mold opening position. Further, in this mold open state, the mold opening / closing drive unit 23 is driven and controlled, and the toggle link mechanism 2 is extended to the maximum to enter the lockup state (step S22). This state is shown in FIG.

  Then, the mold thickness adjusting mechanism 4 is driven and controlled to move the drive panel 12 (movable mold 1 m) forward (step S23). On the other hand, the fluctuation of the operation physical quantity accompanying the forward movement is monitored, specifically, the fluctuation of the load torque T (drive current) of the mold thickness adjusting motor 20 is monitored, and the load torque T reaches a preset threshold value Ts. The mold thickness adjusting mechanism 4 (mold thickness adjusting motor 20) is stopped (steps S24, S25, S26). At this time, the position when the load torque T reaches the threshold value Ts is detected by the distance detector 5, and this position is stored as the mold closing position Xf (step S27). The mold closing position Xf is a reference position where the movable mold 1m and the fixed mold 1c touch. The magnitude of the threshold value Ts can be appropriately set through experiments, adjustments, and the like.

  In addition, although the case where the absolute value of the load torque T is used as the operation physical quantity is shown, the variation rate ΔT of the load torque T may be used. That is, by sequentially obtaining the variation rate ΔT of the load torque T with respect to the constant movement amount ΔX of the movable platen 21 (movable type 1 m), the position when the variation rate ΔT reaches a preset set rate (threshold) Ts is determined. It may be detected as the mold closing position Xf. In this case, the load torque T is normally displayed as a percentage with the maximum torque being 100 [%]. Therefore, when the constant movement amount ΔX of the movable platen 21 is several millimeters, the set rate Ts with respect to the rate of increase ΔT is 1 [ %] Can be set before and after. If such a variation rate ΔT is used, accurate and stable detection can be performed as compared with the case where the absolute value of the load torque T is used. That is, when the absolute value is used, it is directly affected by disturbances such as temperature drift and mechanical friction, and accurate and stable detection cannot be performed. However, such a problem can be avoided by using the variation rate ΔT. There are advantages. The fluctuation rate ΔT may be expressed as a fluctuation amount with respect to the constant movement amount ΔX.

  Next, the mold opening / closing drive unit 23 is driven and controlled, and the toggle link mechanism 2 is shortened to open the mold 1 by a predetermined amount (step S28). Since this mold opening is intended for mold release, a small mold opening amount is sufficient. Thereafter, the mold thickness adjusting mechanism 4 is driven and controlled, and the drive panel 12 is moved backward by a predetermined amount (step S29). Since this backward movement is intended to set a set mold interval Ls, which will be described later, a slight backward movement amount is sufficient. In this state, the mold opening / closing drive unit 23 is driven and controlled, and the toggle link mechanism 2 is brought into the lock-up state again (step S30). Next, the mold thickness adjusting mechanism 4 is driven and controlled, and the drive panel 12 (movable mold 1 m) is moved forward (step S31). On the other hand, the moving amount (displacement amount) of the movable mold 1m is detected by the distance detector 5, and the position where the gap G between the fixed mold 1c and the movable mold 1m becomes the preset set distance Ls, that is, the above-mentioned. If the movable mold 1m is moved to a position obtained by adding the set mold interval Ls to the mold closing position Xf (mold interval set position Xs), the mold thickness adjusting mechanism 4 is stopped (steps S32 and S33). This state is shown in FIG. Thus, by using the mold closing position Xf, there is an advantage that the mold thickness adjusting mechanism 4 can be set (adjusted) accurately and easily at the mold interval setting position Xs with reference to the mold closing position Xf. .

  In this case, the set mold interval Ls is set in advance in the molding machine controller 40 as a gap G between the fixed mold 1c and the movable mold 1m from which the molten resin does not leak during injection molding. That is, the gap G between the fixed mold 1c and the movable mold 1m shown in FIG. 4 is set as the set mold interval Ls. The set mold interval Ls is selected from the range of 0.001 to 0.1 [mm]. The range of 0.001 to 0.1 [mm] is a range in which both the gas venting action and the molten resin leakage preventing action can be satisfactorily realized, and this range was confirmed experimentally. In particular, the level of 0.001 [mm] is a level of mold accuracy required for a mold for molding a CD, a DVD, or the like, and is a level that can be detected by the distance detector D described above.

  Moreover, when moving the movable mold 1m to the position where the set mold interval Ls is reached, an example is shown in which the movable mold 1m is directly moved forward to a position where the set mold interval Ls is obtained. If the mold closing position Xf is reached, the forward movement of the movable mold 1m may be stopped, and thereafter, the movable mold 1m may be moved backward to the position where the set mold interval Ls is obtained. In the former case, there is an advantage that it is possible to improve the ease and speed in setting the set type interval Ls, and in the latter case, certainty and accuracy in setting the set type interval Ls, and further stability. In particular, since the mold 1 is once closed and the set mold interval Ls is set with reference to the immediately preceding mold closing position Xf, it occurs in the mold 1 over time. There is an advantage that an error factor due to expansion and contraction such as thermal expansion can be eliminated.

  Thus, the mold interval setting preparation process is completed, and the process proceeds to a molding process for actually molding. FIG. 1 is a flowchart showing a specific processing procedure during molding.

  At this time, after performing the above-described mold interval setting preparation process, if the process immediately shifts to the molding process, it can be transferred to the molding process as it is. 4 is set to the mold interval setting position Xs (step S1). In this case, as described above, the mold interval setting position Xs for obtaining the set mold interval Ls with reference to the stored mold closing position Xf may be set.

  On the other hand, at the start of the molding process, the mold opening / closing drive unit 23 is driven and controlled, and the toggle link mechanism 2 is brought into a lock-up state (step S2). Thereby, the movable mold 1m moves forward, the mold 1 is closed, and the set mold interval Ls at which a predetermined gap G is obtained between the fixed mold 1c and the movable mold 1m is automatically set (step) S3). This state is the same as that in FIG. In the injection molding method according to the present embodiment, since mold clamping for applying pressure (mold clamping force) to the mold 1 is not performed, the process proceeds to the injection process when the above mold closing operation is completed (step S1). S4). In the injection process, an injection filling process in which the measured molten resin is injected and filled into the mold 1 from the injection device Mi, and a pressure holding process for applying a holding pressure to the resin injected and filled in the mold 1 are performed. Is called. In the injection process, the measured molten resin is injected and filled from the injection device Mi into the mold 1. However, since the mold 1 has a gap G based on the set mold interval Ls, the injection filling in the mold 1 is performed. Inside air and gas are discharged to the outside through the gap G.

  Further, when the injection filling of the molten resin is almost completed, the pressure (resin pressure) in the mold 1 is increased, and the mold 1 opens, that is, the movable mold 1m receives a force in the backward direction. Since the mechanism 2 is in the lock-up state, the backward displacement of the movable mold 1m is prevented. In the lockup state, the toggle link mechanism 2 is in the most extended state, but the mold opening / closing drive unit 23 performs drive control for maintaining the lockup state. However, the power consumption (pressure force) at this time is very small. As a result, the position of the movable mold 1m during the injection process is held constant (fixed).

  When the injection process is completed, the cooling process is performed for a preset cooling time (steps S5 and S6). Further, when the cooling process is completed, a mold opening process for opening the mold 1 is performed (step S7). In the mold opening process, the mold opening / closing drive unit 23 is driven and controlled, and the toggle link mechanism 2 is shortened. As a result, the movable mold 1m moves backward to the mold opening position Xo. Thereafter, the molded product is taken out.

  On the other hand, after the mold is closed by locking up the toggle link mechanism 2, that is, when step S3 is completed, the actual mold interval Ld between the fixed mold 1c and the movable mold 1m is detected by the distance detector 5. (Step S8). If the detected mold interval Ld matches the set mold interval Ls, the correction process is not performed. However, if the detected mold interval Ld does not match the set mold interval Ls, the mold interval Ld is set to the set mold interval Ls. Correction processing is performed so as to match Ls (steps S9 and S10). In this case, the correction process is not particularly limited to a specific correction method. For example, when the mold interval Ld is larger than the set mold interval Ls, the deviation between the mold interval Ld and the set mold interval Ls is set as the set type. Correction can be made by adding to the interval Ls. By performing such correction processing, it is possible to always ensure an accurate set mold interval Ls, which can contribute to further improvement in molding quality and yield. In particular, if the actual mold interval Ld is detected after the mold is closed by locking up the toggle link mechanism 2, the actual mold interval Ld before injection filling can be obtained. There are advantages you can do.

  One molding cycle is completed through the above steps. Thereafter, the same cycle is repeated (steps S11, S2,...).

  According to such an injection molding method according to the present embodiment, the mold thickness adjusting mechanism 4 is moved between the fixed mold 1c and the movable mold 1m where the molten resin does not leak during injection molding with the toggle link mechanism 2 locked up. Since the predetermined gap G (set mold gap Ls) is set to the mold gap setting position Xs, the toggle link mechanism 2 is locked up and the injection process (S4) and the cooling process (S6) are performed. Optimal (ideal) injection molding method that can meet the demands of energy saving from the viewpoint of global environment protection such as reduction of carbon dioxide emission and resource saving. Can be realized. In addition, since the toggle link mechanism 2 is locked up at the time of injection molding, the molten resin is injected and filled into the mold 1 having the set mold interval Ls between the fixed mold 1c and the movable mold 1m. Can be surely and stably vented from the mold 1, thereby contributing to improvement in molding quality and yield. Moreover, since it is possible to avoid a problem that unnecessary and large stress (clamping force) is applied to the mold 1 and the mold opening / closing device Mc, the deterioration and failure of the mold 1 and the mold opening / closing device Mc are suppressed, and the mechanism portion This contributes to longer life, higher accuracy and improved maintainability.

  FIG. 5 shows a comparison of a part of the injection molding method (molding process) according to the present invention and a conventional injection molding method (molding process). As is apparent from the figure, in the injection molding method according to the present invention, a mold for performing mold clamping by applying a substantial pressure (clamping force) to the mold 1 compared to the conventional injection molding method. The tightening process is eliminated.

  By the way, since such an injection molding method according to the present invention does not give a substantial mold clamping force and does not perform position control with respect to the movable mold 1m, there is a possibility that the actual mold interval Ld may vary. There is a risk of variations in molding quality, particularly in the dimension of the molded product in the mold opening / closing direction (X direction). However, in this case, the variation occurs in the X direction and does not occur in the Y direction or the Z direction. Therefore, the injection molding method according to the present invention is disadvantageous for a molded product that requires a high degree of precision in the weight of the molded product and the dimension in the X direction, but a molded product that does not require a high degree of precision in the X direction dimension, For example, it can be used without problems for molding of electrical component connectors and the like, and in this case, benefits such as energy saving can be enjoyed. Therefore, if necessary, a molding mode switching means is provided to switch between the first molding mode using the normal (conventional) injection molding method and the second molding mode (energy saving mode) using the injection molding method according to the present invention. You may do it.

  On the other hand, in FIG. 7, the process sequence at the time of the shaping | molding in the injection molding method which concerns on the modified embodiment of this invention is shown with a flowchart. In FIG. 7, the same steps as those in FIG. 1 are denoted by the same reference numerals to clarify the configuration, and detailed description thereof is omitted. In the modified embodiment shown in FIG. 7, after the injection filling of the molten resin from the injection device Mi to the mold 1 is completed, that is, when step S5 is completed, the actual mold interval between the fixed mold 1c and the movable mold 1m. 1 is different from the embodiment shown in FIG. 1 in that Ld is detected by the distance detector 5 (step S8E). If the detected mold interval Ld matches the set mold interval Ls, the correction process is not performed. However, if the detected mold interval Ld does not match the set mold interval Ls, the mold interval Ld is set to the set mold interval Ls. Correction processing is performed so as to coincide with Ls (steps S9E and S10E). Thus, if the actual mold interval Ld between the fixed mold 1c and the movable mold 1m is detected after the injection filling of the molten resin from the injection apparatus Mi is completed, the actual mold interval Ld after injection filling can be obtained. There is an advantage that the whole influence at the time of molding can be corrected.

  Although the best embodiment has been described in detail above, the present invention is not limited to such an embodiment, and the details, methods, configurations, numerical values, quantities, and the like do not depart from the spirit of the present invention. It can be changed, added, or deleted arbitrarily.

  For example, the set mold interval Ls is desirably set in the range of 0.001 to 0.1 [mm], but the setting other than this range is excluded according to the type of molten resin, mold accuracy, and the like. is not. Moreover, although the case where the distance detector 5 attached to the mold 1 is used for detecting the set mold interval Ls is shown, it may be attached to other parts such as the movable platen 21 and / or the fixed platen 11. Further, although the proximity sensor 5 ps is used as the distance detector 5, the same can be implemented by using another sensor such as an optical sensor or an ultrasonic sensor. On the other hand, although the load torque T accompanying the closing of the mold 1 is used as the operation physical quantity in the detection of the mold closing position Xf, other operation physical quantities may be used.

The flowchart for demonstrating the process sequence of the injection molding method which concerns on the best embodiment of this invention, A flow chart for explaining a processing procedure of a mold interval setting preparation step in the injection molding method, Configuration diagram of a mold opening and closing device provided in an injection molding machine that implements the injection molding method, The block diagram which extracts and shows some distance detectors attached to the metal mold | die of the mold opening / closing apparatus with which the injection molding machine is equipped, Process diagram for explaining the principle of the injection molding method, Schematic diagram for explaining the operating state of the mold opening and closing device when performing the injection molding method, The flowchart for demonstrating the process sequence of the injection molding method which concerns on the modified embodiment of this invention,

Explanation of symbols

  1: mold, 1c: fixed mold, 1m: movable mold, 2: toggle link mechanism, 3: mold opening / closing mechanism, 4: mold thickness adjusting mechanism, 5: distance detector, Mc: mold opening / closing device, Mi: injection device , G: predetermined gap, Ls: set mold interval, Ld: actual mold interval, Xs: mold interval setting position, S4: injection process, S6: cooling process

Claims (7)

  A mold opening / closing mechanism having a toggle link mechanism for opening / closing a mold and a mold opening / closing apparatus having a mold thickness adjusting mechanism for adjusting a mold thickness is injected and filled with a molten resin from an injection device into a mold having a fixed mold and a movable mold. When performing the injection molding, the mold thickness adjusting mechanism is set in advance with a predetermined gap between the fixed mold and the movable mold (the set mold interval between which the molten resin does not leak during the injection molding with the toggle link mechanism locked up). ) Is set to a position (mold interval setting position), and at the time of injection molding, the toggle link mechanism is shortened to open the mold, and the toggle link mechanism is locked up to close the mold. An injection molding method comprising performing at least an injection process and a cooling process in a closed state.   2. The injection molding method according to claim 1, wherein the set mold interval is set in a range of 0.001 to 0.1 [mm].   The injection according to claim 1, wherein a gap (actual mold interval) between the fixed mold and the movable mold is detected using a distance detector attached to the fixed mold and / or the movable mold. Molding method.   By previously driving and controlling the mold thickness adjusting mechanism, the movable mold is moved forward from the mold opening position while the toggle link mechanism is locked up, and the fluctuation of the operation physical quantity accompanying this forward movement is monitored. Then, the position where the operation physical quantity reaches a preset threshold is obtained as a mold closing position, and then the mold thickness adjusting mechanism obtains the set mold distance based on the mold closing position. 4. The injection molding method according to claim 1, wherein the injection molding method is set at a position.   The injection molding method according to claim 4, wherein the operating physical quantity includes a fluctuation rate (fluctuating quantity) of the operating physical quantity.   At the time of injection molding, after the mold is closed by locking up the toggle link mechanism, the actual mold interval between the fixed mold and the movable mold is detected, and the detected mold interval becomes the set mold interval. The injection molding method according to claim 1, wherein correction processing is performed.   During the injection molding, after the injection filling of the molten resin from the injection device to the mold is completed, an actual mold interval between the fixed mold and the movable mold is detected, and the detected mold interval is the set mold interval. The injection molding method according to claim 1, wherein correction processing is performed so that

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