JP2013028156A - Control method for electric press molding machine, and method for manufacturing resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of bounding after mold closing is completed even when mold closing speed is fast or mold clamping force is weak.SOLUTION: A control method for an electric press molding machine 1 includes a shaping process for shaping thermoplastic resin by using the straight-hydraulic electric press molding machine 1 having servo motors 7, 8, and closing molds 2A, 2B until a mold clamping force applied to the molds 2A, 2B reaches a set mold clamping force G; a positioning process for controlling the position of the mold 2A to maintain a distance between the molds 2A, 2B by driving the servo motors 7, 8 with positioning torque Tp as a control tolerance for 0.01 second or more and 1 second or less after the mold clamping force reaches the set mold clamping force G; and a mold clamping process for clamping the molds 2A, 2B with the set mold clamping force G. The set mold clamping force G is applied by performing torque control of the servo motors 7, 8 with set torque T smaller than rated torque, as a control target value, and the positioning torque Tp is larger than the set torque.

Description

  The present invention relates to a method for controlling an electric press molding machine used for compression molding of a resin molded body and a method for manufacturing a resin molded body.

  Conventionally, an electric press molding machine using a servo motor as a drive source can control speed, position, and pressure more accurately than a hydraulic press molding machine, and since it does not use oil, it is also widely used in the industry because it leads to an improved working environment. It has been.

  For example, Patent Literature 1 is known as a technical literature regarding such a control method of an electric press molding machine. This patent document 1 discloses a method for controlling an electric press molding machine that performs mold clamping by performing mold closing by position control for controlling the position of a slide (movable platen) and then switching to torque control for controlling the torque of a servo motor. Is described.

Japanese Patent Laid-Open No. 11-33799

  However, in the conventional control method as described above, when the mold closing speed is fast or when the mold clamping force is small, the position of the slide cannot be held after the mold closing is completed, and the slide opens in the mold opening direction. There was a problem of bouncing.

  Therefore, the present invention provides a method for controlling an electric press molding machine and a method for producing a resin molded body that can suppress the occurrence of bounce after completion of mold closing even when the mold closing speed is high or the mold clamping force is small. The purpose is to do.

The present inventors have found that the object of the present invention can be achieved by performing the following control, and have completed the present invention.
The electric press molding machine control method according to the present invention uses a direct pressure type electric press molding machine using a servo motor as a drive source, and the clamping force applied to a pair of male and female dies is set to a preset clamping force. The mold is closed until it reaches the mold, and the molding process is performed to mold the molten thermoplastic resin, and the setting is performed for 0.01 seconds to 1.0 seconds after the mold clamping force reaches the set mold clamping force. Positioning that maintains the distance between a pair of molds by controlling the position of the movable mold of the mold by driving the servo motor using the preset positioning torque as the control allowable value at the position where the mold clamping force is reached. And a clamping process for clamping the mold with a set clamping force after the positioning process, and the set clamping force in the clamping process is set to a set torque smaller than the rated torque of the servo motor. Servo mode as value Was added to the mold by the torque control coater, positioning torque may be greater than the set torque.

  In the control method for the electric press molding machine according to the present invention, the positioning torque is preferably 100% or more of the rated torque of the servo motor.

  Moreover, in the control method of the electric press molding machine according to the present invention, the positioning step is performed for 0.01 second or more and 1.0 second or less after the detection value of the load cell for detecting the clamping force reaches the set clamping force. During this time, the position of the movable mold is controlled by driving the servo motor using the preset positioning torque as the control allowable value at the position where the set mold clamping force is reached. It is preferable to maintain.

  The electric press molding machine control method according to the present invention controls the speed stable torque that is 100% or more of the rated torque of the servo motor until the detected value of the load cell reaches the set clamping force in the shaping process. It is preferable to close the mold by driving the servo motor as an allowable value to control the position of the movable mold.

  Alternatively, in the shaping process, the electric press molding machine control method according to the present invention is a speed that is 100% or more of the rated torque of the servomotor until the mold closing speed of the mold reaches a preset speed. It is preferable to close the mold by controlling the position of the movable mold of the mold by driving the servo motor with the stable torque as the control allowable value.

  In the control method of the electric press molding machine according to the present invention, the set speed is 30 mm / sec or more.

  The method for producing a resin molded body according to the present invention uses a resin supply step of supplying a molten thermoplastic resin between a pair of male and female dies, and a direct pressure electric press molding machine using a servo motor as a drive source. The molding process closes the mold until the mold clamping force applied to the mold reaches a preset mold clamping force, and the molding process forms the molten thermoplastic resin, and the mold clamping force reaches the set mold clamping force. The position of the movable mold of the mold by driving the servo motor with the preset positioning torque as the control allowable value at the position where the set mold clamping force is reached for 0.01 second or more and 1.0 second or less Setting in the mold clamping process includes a positioning process for maintaining the distance between the pair of molds by performing control, and a mold clamping process for clamping the mold with a set mold clamping force after the positioning process. The clamping force is the rated torque of the servo motor. Was added to the mold by the torque control servo motor smaller set torque as a control target value, the positioning torque may be greater than the set torque.

  According to the present invention, even when the mold closing speed is high or the mold clamping force is small, it is possible to suppress the occurrence of bounce when the mold closing is completed.

It is a figure which shows the electric press molding machine used with the manufacturing method of the resin molding which concerns on 1st Embodiment. It is a graph which shows control of the metal mold | position position of the electric press molding machine which concerns on 1st Embodiment, the moving speed of a metal mold | die, and the torque of a servomotor. It is a flowchart which shows the manufacturing method of the resin molding which concerns on 1st Embodiment. It is a figure which shows the electric press molding machine in a resin supply process. It is a figure which shows the electric press molding machine in a shaping process. It is a figure which shows the electric press molding machine in a positioning process. It is a graph which shows control of the metal mold | position position of the electric press molding machine which concerns on 2nd Embodiment, the moving speed of a metal mold | die, and the torque of a servomotor. It is a flowchart which shows the manufacturing method of the resin molding which concerns on 2nd Embodiment. (A) It is a graph which shows the result of the position change of the metal mold | die in an Example. (B) It is a graph which shows the result of the position fluctuation | variation of the metal mold | die in a comparative example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
The manufacturing method of the resin molding which concerns on 1st Embodiment performs the compression molding of a resin molding using the electric press molding machine 1 shown in FIG. The electric press molding machine 1 performs mold closing, mold clamping, and mold opening of a pair of male and female molds 2A and 2B.

(Electric press molding machine)
As shown in FIG. 1, an electric press molding machine 1 includes a movable platen 3 to which a female die 2A is attached, a fixed platen 4 to which a male die 2B is attached, and the movable platen 3 to the fixed platen 4. Are provided with ball screws 5 and 6 that are reciprocally moved, servo motors 7 and 8 that rotationally drive the ball screws 5 and 6, and a controller 12 that controls the servo motors 7 and 8. The electric press molding machine 1 is a direct pressure type electric press using servo motors 7 and 8 as drive sources.

  The mold 2A and the mold 2B are opposed to each other in the vertical direction. The mold 2A attached to the movable platen 3 is a movable die, and the die 2B attached to the fixed platen 4 is a fixed die. The mold 2 </ b> A and the mold 2 </ b> B approach and separate according to the reciprocating movement of the movable platen 3. In the mold 2B, a resin passage 2a connected to an injection nozzle of an injection machine (not shown) is formed. Molten resin is supplied between the molds 2A and 2B through the resin passage 2a. A load cell 9 for detecting a clamping force applied to the molds 2A and 2B is disposed on the movable platen 3.

  In the ball screws 5 and 6, the gear portions 5 a and 6 a mesh with the output gears of the servo motors 7 and 8, and are driven to rotate by the torque transmitted from the servo motors 7 and 8. The ball screws 5 and 6 are rotatably supported by the bearings 10 and 11, and the nuts 5b and 6b fixed to the movable platen 3 move in the vertical direction by the rotation. The servo motors 7 and 8 are driving sources of the electric press molding machine 1, and the maximum value of the mold clamping torque is 100% or more and 300% or less of the rated torque.

  The control device 12 controls the electric press molding machine 1. The control device 12 controls the servo motors 7 and 8 to perform mold closing, mold clamping, and mold opening of the molds 2A and 2B. The control device 12 controls the rotation speed and torque of the servo motors 7 and 8. The control device 12 detects the position, speed, and the like of the mold 2A from the feedback data of the servo motors 7 and 8.

(Thermoplastic resin)
The thermoplastic resin used for the production of the resin molded body is not particularly limited. For example, polypropylene, polyethylene, acrylic, acrylonitrile-styrene-butadiene block copolymer, polyamide such as polystyrene and nylon, polyvinyl chloride, polycarbonate, styrene-butadiene. Examples thereof include general thermoplastic resins such as block copolymers, thermoplastic elastomers such as EPM and EPDM, mixtures thereof, and polymer alloys using these.

  The thermoplastic resin may contain reinforcing fibers. Examples of the reinforcing fiber include glass fiber, alumina fiber, carbon fiber, organic fiber, and a mixture thereof. Of these, glass fiber, carbon fiber, and organic fiber are preferably used. Examples of the organic fiber include polyethylene fiber, polypropylene fiber, aramid fiber, polyester fiber, vinylon fiber, cotton, hemp, silk, bamboo and the like.

  In addition, as necessary, thermoplastic resins are antioxidants, heat stabilizers, neutralizers, UV absorbers and other stabilizers; silica and other anti-blocking agents; bubble inhibitors; flame retardants; flame retardant aids; Agents; antistatic agents; lubricants; colorants such as dyes and pigments; plasticizers; nucleating agents and crystallization accelerators may be contained. Further, it may contain inorganic compounds such as glass flakes, mica, glass powder, glass beads, talc, clay, alumina, carbon black, wall snite, and the like, powdery and whisker-like inorganic compounds.

  The thermoplastic resin may contain a foaming agent such as a chemical foaming agent or a physical foaming agent. Chemical foaming agents include inorganic foaming agents such as sodium bicarbonate, ammonium bicarbonate and ammonium carbonate, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, azodicarbonamide and azo such as azobisisobutyronitrile. Examples thereof include sulfonyl hydrazides such as compounds, benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, and p-toluenesulfonyl semicarbazide. Moreover, you may add a salicylic acid, urea, and the foaming adjuvant containing these as needed. Examples of physical foaming agents include carbon dioxide and nitrogen. These are preferably in a supercritical state.

  The type of foaming agent is selected in consideration of the melting temperature of the thermoplastic resin to be used, the target foaming ratio, and the like. The addition amount is adjusted in consideration of the strength, density and the like of the target molded article, but is generally 0.1 to 5 parts by mass with respect to 100 parts by mass of the resin.

  A skin material may be bonded to a part of the surface of the resin molded body obtained by the method according to the present invention. Examples of the skin material used in the present invention include woven fabrics and knitted fabrics such as moquettes and tricots, nonwoven fabrics such as needle punch carpets, metal foils, sheets and films of thermoplastic resins and thermoplastic elastomers, and the like. When the skin material is bonded and integrated to a part of the surface of the molded body, the skin material may be previously molded at a predetermined position between the molds.

  Examples of the fibers constituting the nonwoven fabric include natural fibers such as cotton, wool, silk, and hemp, and synthetic fibers such as polyamide, polyester, and nylon. The nonwoven fabric may be composed of a single type of fiber or may be composed of two or more types of fibers. Moreover, you may be comprised with the mixture of a natural fiber and a synthetic fiber. Nonwoven fabrics are classified into needle punch, thermal bond, spunbond, meltblown, and spunlace types, and any nonwoven fabric produced by any method can be applied to the present invention.

  Examples of the thermoplastic resin and thermoplastic elastomer sheets and films include thermoplastic resins such as polypropylene and polyethylene, and polyolefin thermoplastic elastomer sheets and films, and thermoplastic resins used as base resins and Those having good fusibility are preferably used.

  These skin materials may be multilayer skin materials having a foam layer or a backing layer. Examples of the foam layer include polyolefin foams such as polypropylene and polyethylene, polyvinyl chloride foams, soft or semi-rigid polyurethane foams, and the like. Moreover, as a backing layer, a nonwoven fabric, a synthetic resin sheet, a film, etc. are mentioned, for example.

  In addition, these multilayer skin materials are those having good thermal fusion with a thermoplastic resin from the viewpoint of adhesion to a base material portion made of a thermoplastic resin, or a molten thermoplastic resin on the back surface of the skin material. Those that can be bonded to the base resin by impregnating with are preferably used.

(Production method of resin molding)
In the method for manufacturing a resin molded body according to the first embodiment, since the compression molding of the resin molded body is executed with a relatively small set clamping force G, a set torque that is smaller than the rated torque of the servo motors 7 and 8 is set. The molds 2A and 2B are clamped by T. The set mold clamping force G is a mold clamping force preset by the user in order to manufacture a resin molded body having a desired shape, and the set torque T is used to apply the set mold clamping force G to the molds 2A and 2B. Are the control target values of the servo motors 7 and 8.

  Hereinafter, the manufacturing method of the resin molding which concerns on 1st Embodiment is demonstrated focusing on the control method of the electric press molding machine 1. FIG.

  As shown in FIGS. 2 and 3, the control method of the electric press molding machine 1 according to the first embodiment includes a mold closing process for closing the molds 2A and 2B, and a mold 2A that has been closed in a predetermined position. And a positioning process for holding the molds 2A and 2B, and a mold opening process for opening the molds 2A and 2B. The press position shown in FIG. 2 corresponds to the position of the mold 2A (movable platen 3).

<Mold closing process>
The mold closing process includes a high-speed mold closing process (S1) for closing the opened mold 2A to a resin supply position at a high speed, and a resin supply process (S2) in which a molten thermoplastic resin is supplied between the molds 2A and 2B. ) And a shaping step (S3, S4) for shaping the thermoplastic resin by closing the molds 2A, 2B. In this mold closing process, position control by the servo motors 7 and 8 is performed with the position of the mold 2A (movable platen 3) as a control target. For the torque of the servo motors 7 and 8 that fluctuate due to the position change of the mold 2A, a control allowable value that is an upper limit of control is set.

  In the high-speed mold closing process in step S1, the molds 2A and 2B are closed at high speed. In the high-speed mold closing process, the mold 2A and the mold 2B in the opened state are closed to the resin supply position. The resin supply position is a position where supply of molten thermoplastic resin is started between the molds 2A and 2B. The resin supply position is set in advance according to the type of resin to be supplied, the presence or absence of a skin material, the type of skin material, and the like.

  The high-speed mold closing process is performed at a high speed of about 100 mm / sec, for example. In addition, the servo motors 7 and 8 are controlled with a control allowable value of 200% of the rated torque. When the mold 2A reaches the resin supply position, the process proceeds to the resin supply process of step S2.

  In the resin supply step of step S2, a molten thermoplastic resin is supplied in a state where the mold 2A is held at the resin supply position (see FIG. 4). The molten thermoplastic resin is introduced from the injection machine into the resin passage 2a of the mold 2B and supplied between the molds 2A and 2B. The mold closing may be continued without holding the position of the mold 2A in the resin supply process. When the supply of the resin is finished, the process proceeds to the shaping process in step S3.

  In the resin supply step, as described above, the resin may be supplied between the molds 2A and 2B through the resin passage provided in the mold, but a sheet-like or massive molten thermoplastic resin is obtained outside the mold. The molten thermoplastic resin may be supplied between the molds 2A and 2B. Alternatively, a thermoplastic resin sheet is prepared in a separate process in advance, and the mold 2A is heated and softened. 2B may be supplied. In this case, after supplying the sheet-like or lump-shaped thermoplastic resin between the open molds 2A and 2B, the high-speed mold closing process described above is performed, and the process proceeds to the shaping process. The position for shifting from the high-speed mold closing process to the shaping process (molding process start position) is set in advance according to the type of resin to be supplied, the presence or absence of the skin material, the type of the skin material, and the like.

  In the shaping process of step S3, the thermoplastic resin supplied between the molds 2A and 2B is shaped by closing the mold 2A (see FIG. 5). In this shaping process, the servo motors 7 and 8 are controlled with the torque control allowable value as the set torque T and the mold closing speed control target value of the molds 2A and 2B as the set speed V.

  Here, the set speed V is a mold closing speed set in advance according to the type of resin supplied, the type of skin material, the shape and size of the molded body, and the like. If the set speed V is too slow, the fluidity of the resin is lowered and shaping becomes difficult. Further, if the set speed V is too high, the impact on the device or the mold is increased, and there is a possibility of failure or damage. This set speed V is preferably 30 mm / sec or more and 300 mm / sec or less. The set speed V is more preferably 40 mm / sec or more and 250 mm / sec or less, and further preferably 50 mm / sec or more and 200 mm / sec or less.

  When the interval between the molds 2A and 2B becomes narrow in the shaping process, the mold clamping force against the reaction force of the resin is detected by the load cell 9.

  Thereafter, in step S4, it is determined whether or not the detected value of the load cell 9 has reached the set clamping force G. This step S4 is repeated until it is determined that the detected value of the load cell 9 has reached the set clamping force G. When it is determined that the detected value of the load cell 9 has reached the set clamping force G, the process proceeds to the positioning step of step S5.

<< Positioning process >>
In the positioning step of step S5, the position between the molds 2A and 2B is set for a preset positioning time at a position where the detected value of the load cell 9 reaches the set mold clamping force G and then reaches the set mold clamping force G. (See FIG. 6). The positioning time is preferably between 0.01 seconds and 1.0 seconds. This is because if the time is less than 0.01 seconds, sufficient positioning cannot be performed, and if the time exceeds 1.0 seconds, the positioning effect is not affected.

  The position of the mold 2A in the positioning process is shown in FIG. 2 is a structural lower limit position when the molds 2A and 2B are completely closed. In the case of compression molding, the pressurization position changes depending on the amount of the thermoplastic resin supplied between the molds 2A and 2B, but the mold 2A is not normally lowered to the lower end.

  In this positioning step, position control is performed to maintain the distance between the molds 2A and 2B with a preset positioning torque Tp. The positioning torque Tp is larger than the set torque T. The positioning torque Tp is preferably 100% or more of the rated torque of the servomotors 7 and 8. In the positioning step, since the resin is not further compressed, the mold clamping force does not basically exceed the set mold clamping force G. When the positioning time elapses in the positioning process, the process proceeds to the mold clamping process in step S6.

《Clamping process》
In the mold clamping process of step S6, the molds 2A and 2B are clamped with the set mold clamping force G. In the mold clamping process, torque control of the servo motors 7 and 8 is performed with the set torque T as a control target value in order to apply the set mold clamping force G to the molds 2A and 2B. The mold clamping process is performed until a preset cooling time elapses.

  In the torque graph shown in FIG. 2, the part corresponding to the mold closing process, the positioning process, and the mold opening process indicates the control allowable value in the position control, and the part corresponding to the mold clamping process indicates the control target value in the torque control. ing.

  In this mold clamping process, the thermoplastic resin between the molds 2A and 2B is cooled and solidified in a state where the mold is clamped with the set clamping force G, whereby a resin molded body is formed. When the cooling time has elapsed in the mold clamping process, the process proceeds to the mold release process in step S7.

<Mold opening process>
The mold opening process includes a mold release process (S7) in which the molds 2A and 2B are opened at a moderate speed and a high speed mold opening process (S8) in which the mold is opened at a high speed. In this mold opening process, position control is performed with the position of the mold 2A as a control target.

  In the mold release process in step S7, the mold opening is performed at a moderate speed. In the mold release process, the mold 2A is raised from the position of the mold clamping process to a predetermined mold release position. In the mold release process, for example, the servo motors 7 and 8 are controlled using 200% of the rated torque as a control allowable value. When the mold 2A is opened to the mold release position in the mold release process, the process proceeds to the high-speed mold opening process in step S8.

  In the high-speed mold opening process of step S8, the mold opening to the rising end is performed at high speed. In this high-speed mold opening process, the mold opening speed is about 100 mm / sec. For example, the servo motors 7 and 8 are controlled with a control allowable value of 200% of the rated torque.

  After execution of the control method of the electric press molding machine 1 including the above steps S1 to S8, the compression molded resin molded body is taken out from the mold 2B.

  According to the method for manufacturing a resin molded body and the control method for the electric press molding machine 1 according to the first embodiment described above, even when the set speed V is high or the set torque T is small in the mold closing process. Since the positioning process of maintaining the distance between the molds 2A and 2B is performed with the positioning torque Tp larger than the set torque T when the mold closing is completed as a torque control allowable value, the mold 2A (movable platen) is braked when the mold closing is completed. It is possible to suppress the occurrence of bounce in 3). Therefore, according to these methods, it is possible to avoid the occurrence of bouncing due to inertia and adversely affecting the molding of the resin molded body, so that the quality of the resin molded body to be manufactured can be improved.

  Moreover, according to the manufacturing method of the resin molding which concerns on 1st Embodiment, and the control method of the electric press molding machine 1, from the shaping process to the positioning process using the detected value of the load cell 9 provided in the movable platen 3 Therefore, the transition timing can be determined with higher accuracy than when the transition timing is determined from the feedback data of the servo motors 7 and 8. Therefore, according to these methods, the determination of the transition timing can be performed with high accuracy, so that the occurrence of the bounce of the mold 2A can be more reliably suppressed.

[Second Embodiment]
As shown in FIG. 7 and FIG. 8, the method for producing a resin molded body according to the second embodiment has only the contents of the shaping step compared to the method for producing a resin molded body according to the first embodiment. Different.

  Hereinafter, the manufacturing method of the resin molding which concerns on 2nd Embodiment is demonstrated centering on the control method of the electric press molding machine 1. FIG. The control method of the electric press molding machine 1 according to the second embodiment includes a mold closing process, a positioning process, a mold clamping process, and a mold opening process, as in the first embodiment.

<Mold closing process>
As shown in FIGS. 7 and 8, the mold closing process includes a high-speed mold closing process (S11) for closing the opened mold 2A to the resin supply position at a high speed, and a molten heat between the molds 2A and 2B. A resin supply step (S12) in which the plastic resin is supplied and a shaping step (S13, S14, S15, S16) for shaping the thermoplastic resin by closing the molds 2A, 2B are included.

  Since the high-speed mold closing process in step S11 and the resin supply process in step S12 are the same as those in the first embodiment, description thereof will be omitted. When the supply of the resin is finished in the resin supply process of step S12, the process proceeds to the shaping process. Similarly to the first embodiment, after a sheet-like or block-like thermoplastic resin is supplied between the molds 2A and 2B, a high-speed mold closing process may be performed, and the process may proceed to a shaping process.

  The shaping process includes determination of the set speed V (S13), speed stabilization process (S14), normal shaping process (S15), and determination of the set clamping force G (S16). The set speed V is preferably 30 mm / sec or more and 300 mm / sec or less. The set speed V is more preferably 40 mm / sec or more and 250 mm / sec or less, and further preferably 50 mm / sec or more and 200 mm / sec or less.

  In step S13, it is determined whether or not the mold closing speed of the molds 2A and 2B has reached the set speed V. Whether or not the mold closing speed has reached the set speed V is determined based on feedback data from the servomotors 7 and 8, for example. Alternatively, a sensor for detecting the mold closing speed may be provided and the determination may be made based on the detected value. When it is determined that the mold closing speeds of the molds 2A and 2B have not reached the set speed V, the process proceeds to the speed stabilization process of step S14.

  In the speed stabilization process of step S14, the mold closing speed of the mold 2A is accelerated to the set speed V. In this speed stabilization process, position control of the servo motors 7 and 8 is performed with the control allowable value being a speed stable torque Tv of 100% or more of the rated torque instead of the set torque T smaller than the rated torque of the servo motors 7 and 8. The speed stabilizing torque Tv is a torque set in advance to stably accelerate the mold closing speed to the set speed V. In the speed stabilizing step, the thermoplastic resin may or may not be shaped.

  This speed stabilization process is repeated until it is determined in step S13 that the mold closing speed of the mold 2A has reached the set speed V. When it is determined that the mold closing speed has reached the set speed V, the process proceeds to the normal shaping process in step S15.

  In the normal shaping process of step S15, the molds 2A and 2B are closed at the set speed V, whereby the thermoplastic resin is shaped between the molds 2A and 2B. In the normal shaping process, the set torque T is driven to control the position of the mold 2A. When the interval between the molds 2A and 2B becomes narrow in this normal shaping process, the mold clamping force against the reaction force of the resin is detected by the load cell 9.

  Thereafter, in step S16, it is determined whether or not the detected value of the load cell 9 has reached the set clamping force G. Step S16 is repeated until it is determined that the detected value of the load cell 9 has reached the set clamping force G. When it is determined that the detected value of the load cell 9 has reached the set clamping force G, the process proceeds to the positioning step of step S17.

<< Positioning process >>
In the positioning step of step S17, the current position of the mold 2A is set for a preset positioning time at a position where the detected value of the load cell 9 reaches the set mold clamping force G and then reaches the set mold clamping force G. (See FIG. 6). In this positioning step, position control is performed to maintain the distance between the molds 2A and 2B using a preset positioning torque Tp as a control allowable value. When the positioning time has elapsed, the process proceeds to the mold clamping process in step S18.

《Clamping process》
In the mold clamping process of step S18, the molds 2A and 2B are clamped with a set mold clamping force G. In the mold clamping process, torque control of the servo motors 7 and 8 is performed using the set torque T as a control target value in order to maintain the set mold clamping force G. The mold clamping process is performed until a preset cooling time elapses. When the cooling time has elapsed, the process proceeds to the mold opening process.

<Mold opening process>
The mold opening process includes a mold releasing process (S19) for opening the molds 2A and 2B at a moderate speed and a high speed mold opening process (S20) for opening the mold at a high speed. In the mold opening process, position control with the position of the mold 2A as a control target is performed.

  In the mold release process of step S19, the mold opening is performed at a moderate speed. In the mold release process, the mold 2A is raised from the position of the mold clamping process to a predetermined mold release position. When the mold 2A is opened to the mold release position, the process proceeds to a high-speed mold opening process in step S20. In the high-speed mold opening process of step S20, the mold opening to the rising end is performed at high speed.

  After execution of the control method of the electric press molding machine 1 including the above steps S11 to S20, the compression molded resin molded body is taken out from the mold 2B.

  According to the method for manufacturing a resin molded body and the control method for the electric press molding machine 1 according to the second embodiment described above, the same effects as those of the first embodiment can be obtained. Furthermore, according to these methods, since the speed stabilization process for accelerating the mold closing speed to the set speed V using the speed stable torque Tv that is 100% or more of the rated torque as a control allowable value, the set mold closing force G is provided. Even when it is set to be small, the mold closing speed of the molds 2A and 2B can be stabilized. Therefore, according to these methods, when the mold 2A is accelerated, it is avoided that the mold closing speed becomes unstable due to inertia and the shaping of the thermoplastic resin is affected, so that the quality of the resin molded body is improved. be able to.

  In the method for manufacturing a resin molded body and the control method for the electric press molding machine 1 according to the second embodiment, a remarkable effect appears particularly when the set speed V is 30 mm / sec or more.

  The present invention is not limited to the embodiment described above.

  For example, in 2nd Embodiment, the aspect which makes speed stable torque Tv a control allowable value in the whole shaping process may be sufficient. That is, the speed stable torque Tv may be controlled as the control allowable value until the detected value of the load cell 9 reaches the set clamping force G in the shaping process. In this way, the set torque T is set to a small value by controlling the entire shaping process using the speed stable torque Tv that is 100% or more of the rated torque of the servo motors 7 and 8 as a control allowable value. However, the mold closing speed of the molds 2A and 2B can be stabilized.

  The present invention can also be applied to a mechanism in which the electric press molding machine 1 opens and closes the molds 2A and 2B in the horizontal direction instead of the vertical direction.

(Example)
As an example, the manufacturing method of the resin molding which concerns on 1st Embodiment mentioned above was performed. As the thermoplastic resin, Sumitomo Nobrene BUE81E6 (manufactured by Sumitomo Chemical Co., Ltd., polypropylene, MFR = 80 [g / 10 min]) was used.

  As the electric press molding machine 1, SLIM10e16 (manufactured by Sato Iron Works Co., Ltd., direct pressure type electric press molding machine) was used. The rated torque of the servo motors 7 and 8 in the electric press molding machine 1 is 490 kN, the maximum clamping force is 980 kN, and the rotational torque of the servo motor corresponding to this maximum clamping force is 200% of the rated torque. .

  As the molds 2A and 2B, those having a seat back shape were used. The molds 2A and 2B are one-point gate molds having cavities capable of manufacturing a plate-like sheet back molded body having a length of 480 mm, a width of 390, and a thickness of 2.0 mm.

  The temperature of the thermoplastic resin at the time of mold supply was 200 ° C. The clearance between the molds 2A and 2B at the resin supply position was 30 mm.

  The set clamping force G in the mold clamping process was set to 400 kN (the corresponding rotational torque was 82% of the rated torque), and the set speed V in the shaping process was set to 50 mm / sec. Further, the positioning torque Tp in the positioning process was set to 600 kN (the corresponding rotational torque was 122% of the rated torque), and the positioning time was set to 0.2 seconds. The resin molded body was manufactured under the above conditions.

(Comparative example)
In the comparative example, the resin molding was manufactured under the same conditions as in the example except that the positioning process was not performed and the mold clamping process was started immediately after the shaping process.

  In FIG. 9, the result of the position fluctuation | variation of the metal mold | die 2A from a shaping process to a mold clamping process is shown. FIG. 9A is a graph showing the result of the position fluctuation of the mold 2A in the example, and FIG. 9B is a graph showing the result of the position fluctuation of the mold 2A in the comparative example. In each graph, the vertical axis represents the position of the mold 2A, and the horizontal axis represents time.

  As shown in FIG. 9 (a), in the example, there was almost no bounce (position fluctuation) when the mold closing was completed, and the transition to the mold clamping process was performed in a stable state. On the other hand, as shown in FIG. 9B, in the comparative example, a bounce of about 4 mm occurred when the mold closing was completed.

  DESCRIPTION OF SYMBOLS 1 ... Electric press molding machine 2A ... Die (movable type) 2B ... Die (fixed type) 2a ... Resin passage 3 ... Movable platen 4 ... Fixed platen 7,8 ... Servo motor 9 ... Load cell 12 ... Control device G ... Setting Clamping force T ... Set torque Tp ... Positioning torque Tv ... Speed stabilization torque V ... Set speed

Claims (7)

Using a direct pressure type electric press molding machine with a servo motor as a drive source, the mold is closed until the clamping force applied to the pair of male and female dies reaches a preset clamping force, and the molten heat A shaping process for shaping the plastic resin;
When the mold clamping force reaches the set mold clamping force, the positioning torque set in advance at the position where the set mold clamping force is reached for 0.01 second or more and 1.0 second or less is used as the control allowable value. A positioning step of maintaining a distance between the pair of molds by driving a servo motor to perform position control of the movable mold,
A mold clamping step for clamping the mold by the set clamping force after the positioning step;
The set mold clamping force in the mold clamping step is applied to the mold by torque controlling the servo motor with a set torque smaller than the rated torque of the servo motor as a control target value,
The method for controlling an electric press molding machine, wherein the positioning torque is larger than the set torque.   The method of controlling an electric press molding machine according to claim 1, wherein the positioning torque is 100% or more of a rated torque of the servo motor.   In the positioning step, the detection value of the load cell for detecting the clamping force reaches a set clamping force for 0.01 second or more and 1.0 second or less from when the set clamping force is reached. 3. The distance between the pair of molds is maintained by controlling the position of the movable mold of the mold by driving the servo motor using a preset positioning torque as a control allowable value. Control method for electric press molding machine.   In the shaping step, the servo motor is driven with a speed stable torque that is 100% or more of the rated torque of the servo motor as a control allowable value until the detected value of the load cell reaches the set clamping force. The control method of the electric press molding machine of Claim 3 which closes the said metal mold | die by performing position control of the movable mold of a metal mold | die.   In the shaping step, the servo motor is driven with a speed stable torque that is 100% or more of the rated torque of the servo motor as a control allowable value until the mold closing speed of the mold reaches a preset set speed. The method for controlling an electric press molding machine according to any one of claims 1 to 3, wherein the mold is closed by controlling the position of the movable mold of the mold.   The method for controlling an electric press molding machine according to claim 5, wherein the set speed is 30 mm / sec or more. Using a resin supply process for supplying a molten thermoplastic resin between a pair of male and female dies and a direct pressure type electric press molding machine using a servo motor as a drive source, the clamping force applied to the dies is preset. The mold is closed until the set clamping force is reached, and a molding process for shaping the molten thermoplastic resin, and 0.01 seconds or more from when the clamping force reaches the set clamping force By controlling the position of the movable mold of the mold by driving the servo motor with a preset positioning torque as a control allowable value at a position where the set mold clamping force is reached for 1.0 second or less, A positioning step for maintaining a distance between the pair of molds;
A mold clamping step for clamping the mold by the set clamping force after the positioning step;
The set mold clamping force in the mold clamping step is applied to the mold by torque controlling the servo motor with a set torque smaller than the rated torque of the servo motor as a control target value,
The said positioning torque is a manufacturing method of the resin molding larger than the said setting torque.

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