JP4024778B2 - Method for controlling mold clamping device - Google Patents

Description

  The present invention relates to a control method for facilitating engagement in a mold clamping device that allows an engagement portion of a tie bar to be engaged with an engagement means so that a movable plate can be clamped to a fixed plate.

  A mold opening / closing means for moving the fixed plate to which the fixed mold is attached and the movable plate to which the movable mold is attached to each other, and a tie bar for connecting the fixed plate and the movable plate via an engaging means; A driving means for enabling engagement by changing a relative position between the engaging means and the engaging portion of the tie bar; and a tension for the tie bar to generate the fixed mold and the movable mold. When performing an injection press or injection compression molding by a clamping device comprising a clamping means for clamping, the fixing is performed in a state where the movable mold is in contact with the stationary mold and the volume of the mold cavity is increased. It is necessary to inject after the board and the movable board are engaged through a tie bar. As described above, when positioning the movable platen in a state where the fixed mold and the movable mold are not in contact with each other by means of hydraulic mold opening / closing means that does not use a servo mechanism, the flow of speed from the approach position closes the mold. Because it becomes irregular due to changes in speed setting, mold weight, sliding resistance of the movable platen, etc., the movable platen stop position cannot be obtained stably and accurately, in which case it is an engagement means The half nut could not be engaged.

  In order to avoid such a situation, the mold closing speed was switched from a position before the approach position to a constant value not set by the operator of the molding machine, but the movable platen stop position could not be stabilized sufficiently. It was.

As a mold clamping device having the above-described configuration, there is one disclosed in Patent Document 1. However, the engagement method between the tie bar and the half nut in the mold clamping device of Patent Document 1 relates to a mold thickness adjusting method, which is performed at a position where the reference mold is closed before molding, as in the present application. No major issues arise.
JP-A-8-276482 (pages 1 to 5, FIGS. 1 and 2)

  The present invention has been made in order to solve the above-described problems, and is an engagement in a mold clamping device in which an engaging portion of a tie bar is engaged with an engaging means so that the movable plate can be clamped to the fixed plate. It is an object of the present invention to provide a control method that can easily execute the process and reduce the molding cycle time.

  The invention according to claim 1 of the present invention relates to a mold opening / closing means for moving the fixed platen to which the fixed die is attached and the movable platen to which the movable die is attached to each other, and the fixed platen and the movable platen. A tie bar connected via a coupling means, a drive means for enabling engagement by changing the relative position of the engaging means and the engaging portion of the tie bar, and generating a tension in the tie bar to move the fixed mold. In a method of controlling a mold clamping device comprising a clamping means for clamping a mold, a tie bar and either the fixed platen or the movable platen are placed at a movable platen stop position before the movable die comes into contact with the fixed die. In order to engage with the engaging means, when the engaging portion and the engaging means are not engaged, the tie bar or the engagement is set at a position corresponding to the predicted position of the movable platen based on the movable platen stop position until the previous molding cycle. The combination means is moved.

  According to a second aspect of the present invention, in the first aspect, the predicted position of the movable platen stop is such that the engagement center of the engagement means and the engagement center of the engagement portion are directly opposed at the movable platen stop position or the movable platen stop position. It is calculated from the position of the tie bar in this state, and the tie bar or the engagement means is moved to a position corresponding to the movable platen stop predicted position when the engagement portion and the engagement means are not engaged.

  According to the control method of the present invention, since the engagement between the fixed platen and the movable platen via the tie bar is easily performed, the molding time can be shortened.

  Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view of a main part of a mold clamping device and a control device thereof for carrying out the present invention. FIG. 2 is a graph illustrating the control method of the present invention. FIG. 3 is a flowchart for explaining the control method of the present invention.

  As shown in FIG. 1, a mold clamping device 1 of an injection press machine includes a fixed plate 6 to which a fixed mold 3 is attached and a movable plate 5 to which a movable mold 2 is attached. A cavity 7 having a variable volume is formed between the molds 4. A cylinder of a hydraulic cylinder, which is a mold opening / closing means 21 for moving the fixed plate 6 and the movable plate 5 toward and away from each other, is fixed above one side of the fixed plate 6 and below the other side, respectively. The rods are respectively fixed to the movable platen 5. When the mold is opened / closed, the movable platen 5 is moved toward and away from the fixed platen 6 by the mold opening / closing means 21. By using a hydraulic cylinder for the mold opening / closing means 21, the cost of the mold clamping device 1 can be reduced as compared with the case where a servo mechanism is used.

  In the vicinity of the four corners of the stationary platen 6, mold clamping cylinders, which are clamping means 18 for clamping the fixed mold 3 and the movable mold 2 by generating tension on the tie bar 13, are arranged. The mold clamping cylinder is a double acting cylinder in which a piston 14 is slidably disposed inside a cylinder 15 and a pressure clamping chamber 16 and a mold opening chamber 17 are formed on both sides of the piston 14. A tie bar 13 is fixed on both sides of the piston 14 of the mold clamping cylinder to connect the stationary platen 6 and the movable platen 5 through engaging means 20 described later. One (movable platen side) of the tie bar 13 is formed longer than the other and is inserted into holes formed in the vicinity of the four corners of the movable platen 5. At a predetermined position of the tie bar 13, an engagement portion 19 formed of a plurality of grooves formed in a direction orthogonal to the axial direction is provided. Further, a half nut having meshing teeth is provided as the engaging means 20 on the side of the movable platen 5 opposite to the fixed platen. The engaging means 20 is moved forward and backward by the cylinder with respect to the engaging portion 19, and the meshing teeth of the half nut are engaged with any groove of the engaging portion 19. Therefore, the mold clamping device 1 changes the position of the engaging portion 19 that is engaged with the half nut even if the mold thickness of the mold 4 to be attached is changed or the stroke of the mold clamping cylinder is changed. This is possible. The other side of the tie bar 13 slightly protrudes from the fixed platen 6 toward the non-movable platen side. Further, a position sensor 22 is disposed between the fixed plate 6 and the movable plate 5 at positions close to the insertion positions of the pressure-clamping means 18 and the tie bar 13, and four positions of the movable plate 5 with respect to the fixed plate 6 are provided. Can be detected.

  The tie bar 13 is moved to the non-movable plate side of the fixed platen 6, and the drive unit 10 of the drive unit 12 is made engageable by changing the relative position between the engagement unit 19 and the engagement unit 20. Is arranged. The drive unit 10 includes a servo motor provided with an encoder that is a position sensor. In the present embodiment, the drive unit 10 and the other of the tie bar 13 are connected by a link 11. The clamping means 18, the mold opening / closing means 21, and the engaging means 20 are driven by a hydraulic mechanism (not shown). In particular, the hydraulic oil is supplied to the clamping chamber 16 of the cylinder 15 that is the clamping means 18 by a servo valve. Is controlled by. The mold clamping device 1 is provided with a control device 23. A limit switch (not shown) for confirming each position of the movable platen 5 by the position sensor 22, the position of each tie bar 13 with respect to the fixed platen 6 by the encoder of the drive unit 10, and the engagement between the engagement means 20 and the engagement portion 19. Are sent to the control device 23. In the control device 23, the relative position between the movable platen 5 and the tie bar 13 can also be calculated by calculation. Further, a control signal is sent from the control device 23 to the mold opening / closing means 21, the pressure clamping means 18, the driving means 12, the engagement means 20, and the like. An injection device 9 is disposed on the side of the fixed plate 6 opposite to the movable plate, and the molten material 8 can be injected and filled from the injection device 9 into the cavity 7.

  Next, the mold clamping control of the mold clamping apparatus 1 of the injection press machine will be described with reference to the graph of FIG. 2 and the flowchart of FIG. Prior to the description, the outline of the graph of FIG. 2 will be described. The central horizontal axis represents the movable platen position, and the vertical axis represents the movable platen speed. Therefore, in FIG. 2, the deceleration state before the movable platen 5 is stopped is indicated by the right-downward oblique line. Furthermore, the hatched line of the downward convex shape described above the horizontal axis line schematically represents the meshing teeth of the engaging means 20 when the movable platen 5 stops. A point C shown at the center of the meshing teeth represents the center of engagement of the engagement means 20. Furthermore, a concave hatched line written below the horizontal axis schematically represents an engagement groove of the engagement portion 19 of the tie bar 13. A point F shown at the center of the engagement groove represents the engagement center of the engagement portion 19. In FIG. 2, the engagement center F of the engagement portion 19 in the tie bar 13 represents a position facing the intermediate position between the lower limit G1 of the movable platen stop position and the upper limit G2 of the movable platen stop position (of the tie bar 13). Details on the position will be described later). The engaging means 20 is engageable when the engagement center C is between the engageable range E1 and the engageable range E2 with the engagement center 19 as the center. Note that the distance between the engageable range E1 and the engageable range E2 is the clearance between the engagement tooth and the engagement groove when the engagement center C of the engagement means 20 and the engagement center F of the engagement portion 19 face each other. It is almost the same as the distance E3 + E4.

  In the mold clamping control of the mold clamping apparatus 1, first, the hydraulic cylinder as the mold opening / closing means 21 is operated, and the movable platen 5 is set to a movable position set in front of the mold contact position B from the mold opening completion position. It is moved toward the board stop position G (S1). The reason why the movable platen 5 is temporarily stopped at the movable platen stop position G is because the tie bar 13 and the movable platen 5 are engaged by the engaging means 20. When the movable platen 5 reaches the approach position A shown in FIG. 2 (S2), the movable platen 5 is temporarily stopped. However, since the movable platen 5 is heavy, the movable platen stops from the approach position A due to inertia. It moves to the position G and is temporarily stopped (S3). The movable platen stop position G at that time stops within the range of the lower limit G1 of the movable platen stop position to the upper limit G2 of the movable platen stop position, but is not constant. In this embodiment, the mold is closed by two mold opening / closing cylinders, but the parallelism of the movable platen 5 with respect to the fixed platen 6 at the movable platen stop position G is often not completely parallel.

  The movable platen stop position G with respect to the fixed platen 6 when the movable platen 5 is stopped is detected by the position sensor 22 and stored and stored in the control device 23 (S4). The movable platen stop position G stored and stored in the control device 23 is used as a movable platen stop predicted position in the next molding cycle (details will be described later). Then, from the movable platen stop position G and the position of the tie bar 13 detected by the encoder that is the position sensor of the driving means 12, the half nut that is the engaging means 20 is engaged with the engaging portion 19 of the tie bar 13. Judgment is possible (S5). When the movable platen stop position G is between the engageable range E1 and the engageable range E2, and it is determined that the engaging means 20 and the engaging portion 19 can be engaged as they are (Y), the engaging means 20 is engaged (S7). The engagement center C of the engaging means 20 in the stopped movable platen 5 is between the lower limit G1 of the movable platen stop position and the lower limit E1 of the engageable range, or the upper limit E2 of the engageable range and the movable platen stop position. If it is determined that the engaging means 20 and the engaging portion 19 cannot be engaged with each other as it is (N), the driving means 12 is actuated and the engaging portion 19 of the tie bar 13 is engaged. The tie bar 13 is moved so that the alignment center F faces the engagement center C of the engagement means 20 in the movable platen 5 (S6). Therefore, after the movable platen 5 is temporarily stopped, the tie bar 13 may be moved within the range of the tie bar moving distance D1 + D2. The state in which the engagement center C of the engagement means 20 and the engagement center F of the engagement portion 19 face each other is when the engagement means 20 is engaged with the engagement portion 19. This is a state in which gaps E3 and E4 formed between both side surfaces of the meshing teeth and both side surfaces of the groove of the engaging portion 19 are formed at equal intervals.

  When the engagement by the engagement means 20 is completed, hydraulic oil is supplied to the pressure chamber 16 or the mold opening chamber 17 of the cylinder 15 which is the pressure means 18, and the movable platen 5 is moved forward and backward at a very low speed, so that the mold contact position is reached. The position is moved to a position before B, a cavity 7 having a variable volume is formed between the fixed mold 3 and the movable mold 2, and the movable platen 5 is stopped again. From the injection device 9, the molten material 8 is injected and filled into the cavity 7 of the mold 4. Almost simultaneously, hydraulic oil is supplied to the pressure chamber 16 to increase the pressure, and the molten material 8 in the cavity 7 is compressed. At this time, the mold clamping cylinder is controlled in parallel by a servo valve. Thereafter, when the cooling of the molded product in the cavity 7 is completed, the pressure chamber 16 is depressurized. Next, hydraulic fluid is supplied to the mold opening chamber 17, and the movable platen 5 is opened by a predetermined distance by the pressing means 18 (S8). When the movable platen 5 is moved to the half nut engagement release position (S9), the engagement between the engagement means 20 and the engagement portion 19 is then released (S10). The position of the tie bar 13 when the engaging means 20 and the engaging portion 19 are released is compared with the position of the tie bar 13 when the engaging means 20 and the engaging portion 19 are engaged. The distance between the mold opening stroke and the mold opening stroke is different, and the amount of movement of the gaps E3 and E4 between the engaging means 20 and the engaging portion 19 at that time is also different, so that the position of the tie bar 13 relative to the stationary platen 6 changes. Yes. Then, mold opening of the movable platen 5 is started by the mold opening / closing means 21 (S11) and moved to a mold opening completion position (S12). Then, the position of the tie bar 13 with respect to the fixed platen 6 is adjusted by the driving means 12 in preparation for the engagement of the engaging means 20 and the engaging portion 19 in the next molding cycle at the mold opening completion position.

  The position adjustment of the tie bar 13 will be described. First, the position of the tie bar 13 is calculated in the next molding cycle. The position of the tie bar 13 is calculated based on the previous movable platen stop position G stored and stored in the control device 23 (S13). The tie bar 13 displaced in the previous molding cycle has the position of the engagement center C of the engagement means 20 at the movable platen stop position G in the previous molding cycle and the engagement center F of the engagement portion 19 of the tie bar 13. It is confirmed whether or not the position is a directly facing position (S14), and the tie bar 13 is moved to the facing position (S15). This point will be further described. In the present embodiment, it is assumed that the movable platen 5 is likely to stop at the movable platen stop position G in the previous molding cycle during the next molding cycle. 13 is moved to a position corresponding to the movable platen stop predicted position. By doing so, the possibility of moving the tie bar 13 after the movable platen 5 stops at the movable platen stop position G during the next molding cycle (S16) is reduced, and an improvement in the molding cycle time can be expected. Therefore, the movable platen stop predicted position in the present invention is a variable position because it is calculated based on the movable platen stop position G in the molding cycle up to the previous time. Therefore, unlike the conventional tie bar misalignment correction control method, the misalignment of the tie bar due to the stroke of the clamping cylinder, etc. is corrected to the same position when the mold opening is completed, not based on the movable platen stop position until the previous molding cycle. The content is fundamentally different from what you do. In the above description, the pressing means 18 and one axis of the tie bar 13 have been described, but the same control is simultaneously performed on the four axes.

  As another embodiment, what is stored and stored in the control device 23 is not the position data of the movable platen stop position G, but the engagement center C of the engagement means 20 and the engagement portion 19 at the movable platen stop position G. The position of the tie bar 13 with the engagement center F facing each other may be used. In that case, the engagement means 20 and the engagement portion 19 cannot be engaged at the movable platen stop position G, and the engagement center F of the engagement portion 19 is the same as the engagement center C of the engagement means 20. When the tie bar 13 is moved so as to match, the position of the moved tie bar 13 is stored and stored. Further, when the engagement center C of the engagement means 20 is in the engageable range E1 to the engageable range E2, and the tie bar 13 is engaged without being moved, the position of the tie bar 13 is not The position of the tie bar 13 is stored and stored under the assumption that the engagement center F of the engagement portion 19 faces the engagement center C of the engagement means 20.

  In addition, the control unit 23 does not store / store the movable platen stop position G at the previous molding cycle as the movable platen stop predicted position, but stores the movable platen at a plurality of molding cycles up to the previous cycle. A value based on the average value of the stop positions G may be stored and stored as a movable platen stop predicted position and used for position adjustment of the tie bar 13. In such a case, various applications may be considered, such as excluding those that deviate by a certain amount or more in absolute value. If the movable platen stop position G deviates more than a certain value, the data is not adopted as the movable platen stop prediction position, and the intermediate position between the lower limit G1 of the movable platen stop position and the upper limit G2 of the movable platen stop position is moved next time. It is good also as a board stop prediction position. Further, the movement of the tie bar 13 by the driving means 12 is not limited to the mold opening completion position (when the mold opening is completed), and may be performed when the engaging portion 19 of the tie bar 13 and the engaging means 20 are not engaged. .

  The injection press of the present embodiment does not limit the size of the injection press machine or the molded product, but is a bumper and fuel tank that require a relatively large projected area, a thin plate thickness, and parallelism of the movable platen with respect to the fixed platen. It is suitably used for molding a molded product such as a light diffusion plate. Therefore, a hydraulic mechanism is preferably used as the clamping means 18 instead of an electric motor. Further, the present invention is not limited to the injection press machine, but can be applied to the one in which the movable plate is temporarily stopped before the mold contact position and the half nut is engaged, and is also used for the injection compression molding machine, etc. Is done.

Further, the arrangement of the clamping device in the injection press machine or the injection compression molding machine is not limited to the above. For example, a mold clamping cylinder and an engagement means fixed to the mold clamping cylinder may be provided on the fixed plate, a tie bar may be fixed to the movable plate, and an engagement portion may be provided on the tie bar. In that case, when the engaging portion of the tie bar and the engaging means are not engaged, the position of the mold clamping cylinder and the engaging means with respect to the fixed platen is stored from the movable platen stop position at the time of the previous molding and the movable platen stop. Move to a position corresponding to the predicted position.
Alternatively, the movable platen may be provided with a pressing means and an engaging unit, and the fixed platen may be fixed with a tie bar provided with an engaging portion. Also in this case, the position of the mold clamping cylinder and the engagement means with respect to the movable platen when the engagement portion and the engagement unit are not engaged is stored as the movable platen stop predicted position stored from the movable platen stop position at the previous molding. Move to a position corresponding to.
Further, a mold clamping cylinder may be provided on the movable platen, and an engaging means may be provided on the fixed platen. In that case, the position of the mold clamping cylinder and the tie bar with respect to the movable platen when the engaging portion and the engaging means are not engaged is a position corresponding to the predicted movable plate stop position stored from the movable platen stop position at the previous molding. Move to.
Furthermore, a pressure plate movable with the movable plate is inserted into a tie bar fixed to the fixed plate and provided with an engaging portion, and a pressing means is disposed between the pressure plate and the movable plate. Good. In the above, the press platen is provided with engaging means for engaging with the engaging portion of the tie bar. In that case, when the engagement portion and the engagement means are not engaged, the position of the pressure plate relative to the movable plate is set to a position corresponding to the predicted movable plate stop position stored from the movable plate stop position at the time of the previous molding. Move. The present invention can be applied to a so-called vertical molding machine in which the movable platen is moved in the vertical direction with respect to the fixed platen, in addition to the movable platen being moved in the horizontal direction with respect to the fixed platen.
As for the driving means for moving the engaging portion or the engaging means, the position correction by the clamping cylinder operation is performed by the cylinder mechanism, and the position correction by the movable platen stop position may be performed by the servo motor mechanism. May be performed by a servo motor mechanism.

  The present invention is not limited to the embodiments described above, and various modifications can be added and implemented without departing from the spirit of the invention.

It is explanatory drawing of the principal part of the mold clamping apparatus which implements this invention, and its control apparatus. It is a graph explaining the control method of this invention. It is a flowchart explaining the control method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold clamping device 2 Movable mold 3 Fixed mold 4 Mold 5 Movable plate 6 Fixed plate 7 Cavity 8 Molten material 9 Injection device 10 Drive part 11 Link 12 Drive means 13 Tie bar 14 Piston 15 Cylinder 16 Pressure chamber 17 Mold opening Chamber 18 Clamping means 19 Engaging portion 20 Engaging means 21 Mold opening / closing means 22 Position sensor 23 Control device A Approach position B Mold contact position C, F Engagement center D1, D2 Tie bar movement distance E1 Engageable range Lower limit E2 Upper limit of engageable range E3, E4 Gap G Movable platen stop position G1 Movable platen stop position lower limit G2 Movable platen stop position upper limit

Claims (2)

A mold opening / closing means for moving the fixed plate to which the fixed mold is attached and the movable plate to which the movable mold is attached to each other, and a tie bar for connecting the fixed plate and the movable plate via an engaging means; A driving means for enabling engagement by changing a relative position between the engaging means and the engaging portion of the tie bar; and a tension for the tie bar to generate the fixed mold and the movable mold. In a method of controlling a mold clamping device comprising a clamping means for clamping,
In order to engage the tie bar with either the fixed platen or the movable platen by the engaging means at the movable platen stop position in the next molding cycle just before the movable die comes into contact with the fixed die. A mold characterized in that the tie bar or the engagement means is moved to a position corresponding to a movable plate stop predicted position based on the movable plate stop position up to the previous molding cycle during the mold opening or mold opening completion position. Method of controlling the fastening device. The movable platen stop predicted position is calculated from the position of the tie bar in which the engagement center of the engagement means and the engagement center of the engagement portion are opposed to each other at the movable platen stop position or the movable platen stop position. The method for controlling a mold clamping apparatus according to claim 1, wherein:

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