JP2019077041A - Hollow molding method and hollow molding device - Google Patents

Abstract

To provide a hollow molding method that takes it into account that a molding die should not be damaged due to generated excessive mold closing force when mold closing is performed while a molded article or burrs is left in the molding die from a previous shot.SOLUTION: In a mold closing device of this invention configured to control operation of mold closing/mold opening of a molding die, a torque waveform during normal operation of a mold closing servo motor is acquired in advance as a torque reference waveform and stored. Every time the mold closing device performs the mold closing operation, an actual torque waveform during the mold closing operation of the mold closing servo motor and the torque reference waveform are compared with each other. When a timing of rising of the actual torque waveform comes faster than the torque reference waveform by a predetermined time period, the operation of the mold closing servo motor is immediately stopped as torque abnormality operation.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a hollow molding method and a hollow molding apparatus in which foreign substances generated during a previous molding shot are not caught when the molding die grips a parison in hollow molding.

  In a general hollow forming apparatus, a synthetic resin parison melted and discharged from a die head connected to an extruder is introduced into a forming mold, the forming mold is closed by a mold clamping apparatus, and the parison is held by a cutter. Then, the air blowing nozzle of the driving device is lowered and driven into the parison, and compressed air is blown into the parison to expand the parison, and the parison is closely adhered to the cavity of the molding die to obtain a hollow molded article.

  In such a hollow molding apparatus, a hollow molded product obtained by blow molding a parison is suspended together with the upper bar to a lowered and driven air blowing nozzle and transferred and held by a holder attached to the molding die. At the same time, as the air blowing nozzle is further raised, the nozzle is released from the nozzle and then moved to the take-out position while being held by the product holder.

  In such hollow molding, when the molding die grips a parison, conventionally, foreign substances such as molded product residue at the time of the previous shot are not bitten by the upper part of the mold clamping device so as not to bite foreign substances. If a contact sensor is attached and the contact sensors are not in contact with each other when the clamping servomotor is rotated to a predetermined position, an alarm is output as foreign matter detection to stop the molding machine.

  In addition, the mold clamping device of the hollow molding machine described in Patent Document 1 is known as a countermeasure against excessive mold clamping (overmold clamping) caused by deformation of tie bars, etc., although it is not a countermeasure against foreign matter biting as described above. ing.

  In the mold clamping device described in Patent Document 1, as a measure against over-mold clamping, as shown in FIG. 1 of the same document, the mold opening / closing interlocking mechanism 50 has e.g. , 32, and the detection signal 35 of these sensors is used to prevent breakage of the mold opening / closing interlocking mechanism 50.

Japanese Patent Application Laid-Open No. 11-105117

  In the conventional hollow molding apparatus in which the contact sensor is provided on the upper part of the mold clamping device described above, even if foreign matter is present, even if the mold clamping servomotor bites the foreign matter prior to the detection of the contact sensor. By continuing the mold closing operation, there is a risk of stopping as an overload. In addition, there is also a possibility that due to the deterioration of the contact sensor, it is recognized that the contact sensors are in contact with each other as an abnormality.

  In the case of providing the electromechanical transducing sensors 30, 31, 32 of Patent Document 1 described above, the mold opening / closing interlocking mechanism 50 can be protected but the signals 35 of the electromechanical transducing sensors 30, 31, 32 output abnormal values. When this happens, foreign matter biting progresses, and there is a risk that the foreign matter will cause damage to the mold.

  The present invention is intended to solve the problems of the prior art as described above, and at the time of mold clamping, a mold or a burr at the time of the previous molding shot remains in the mold. An object of the present invention is to realize a hollow molding method and a hollow molding apparatus which take measures so as not to cause excessive mold clamping force and damage to a mold when they are tightened.

  In order to achieve the above object, in the hollow molding method according to the present invention, a torque waveform at the time of normal operation of a mold-clamping electric motor is used in advance as a torque reference waveform for a mold clamping device that controls mold closing and mold opening operations of a mold. The actual torque waveform at the time of mold closing operation of the mold clamping electric motor is compared with the torque reference waveform each time the mold clamping device performs the mold closing operation, and When the timing of the rise of the torque waveform is early, the operation of the clamping electric motor is stopped as the torque abnormality processing.

  In this case, as a desirable mode, as described in claim 2, when the timing of rise of the actual torque waveform is earlier than the timing of rise of the torque reference waveform by a predetermined time or more, torque abnormality processing is performed. The operation of the clamping electric motor is to be stopped. The above setting time is determined in consideration of, for example, a mold closing speed, a distance of a low speed operation, a thickness of a substance to be detected as a foreign matter, a repeat accuracy of the operation, and the like.

  The hollow molding apparatus according to the present invention, as described in claim 3, monitors the torque at the time of mold closing operation of the mold clamping electric motor with respect to the mold clamping apparatus which controls the mold closing and mold opening operation of the molding die. And a control unit that executes abnormality processing. And while the control device acquires beforehand the torque waveform at the time of normal operation of the mold clamping electric motor as a torque reference waveform, every time the mold clamping apparatus performs a mold closing operation, The actual torque waveform at the time of mold closing operation and the torque reference waveform are compared, and when the timing of rising of the actual torque waveform is earlier than the torque reference waveform, the operation of the clamping electric motor is stopped as torque abnormality processing. It is a thing.

  In this case, as a desirable mode, as described in claim 4, as the torque abnormality processing, the timing of the rise of the actual torque waveform is earlier than the timing of the rise of the torque reference waveform by a predetermined time or more. The operation of the clamping electric motor is to be stopped. The above setting time is determined in consideration of, for example, a mold closing speed, a distance of a low speed operation, a thickness of a substance to be detected as a foreign matter, a repeat accuracy of the operation, and the like.

  Therefore, in the invention according to claims 1 and 3, even if a molded product or "bar" on the previous molding shot at the time of mold closing remains temporarily in the molding mold, it is set to the mold at the mold closing operation. An abnormality can be determined from the torque waveform before the mold clamping force is applied, and the molding machine can be stopped at that point.

  Further, in the invention according to claims 2 and 4, since the set time for abnormality judgment can be arbitrarily set, molding machine operating conditions such as mold closing speed and distance for low speed operation, foreign object detection accuracy, etc. Detection accuracy can be determined.

  As described above, according to the present invention, the actual torque waveform at the time of mold closing operation is monitored, and when the rising timing of the actual torque waveform is earlier than the rising timing of the torque reference waveform, the mold clamping electric motor is processed as torque abnormality processing. As a result, it is possible to prevent the molding die from being subjected to an excessive clamping force exceeding a setting and to prevent damage to the molding die in advance.

BRIEF DESCRIPTION OF THE DRAWINGS The front view which shows embodiment of the hollow molding apparatus which concerns on this invention. FIG. 2 is a left side view of the hollow molding apparatus shown in FIG. 1; FIG. 3 is an enlarged side view of a mold clamping device of the hollow molding apparatus shown in FIG. 2; FIG. 2 is a block diagram showing a control device of the hollow molding apparatus shown in FIG. 1; FIG. 5 is a flowchart showing the processing procedure of the control device shown in FIG. 4; FIG. 4 shows a torque waveform of a mold clamping servomotor shown in FIG. 3, in which the horizontal axis represents time and the vertical axis represents torque.

  Hereinafter, an embodiment of a hollow molding apparatus according to the present invention will be described based on FIGS.

  The hollow molding apparatus according to the present embodiment, as shown in FIGS. 1 and 2, sends the molten synthetic resin sent from the extruder 1 to the die head 2 joined at the tip of the extruder 1, It discharges as a parison. The dropped parison is introduced into the mold 3 in the mold open state, the mold 3 is closed and clamped by the action of the mold clamping device 4 to hold the parison, and the parison is a cutter such as a hot cutter (shown It is cut at a) and embedded in the molding die 3. The molding die 3 comprises a pair of half molds 3a and 3b.

  The half mold 3a is mounted on the front platen 5 and the half mold 3b is mounted on the rear platen 6, and the action of the clamping device 4 moves the front platen 5 back and forth relative to the rear platen 6 3a and 3b are designed to be opened and closed.

  The molding die 3 holding the parison is moved integrally with the mold clamping device 4 by the molding die moving device 10 from the lower side of the die head 2 to the lower side of the molding device 7, and the two air blows of the molding device 7 are blown. The nozzle 8 is lowered and driven in, and compressed air is blown into each parison through each air blowing nozzle 8 so that the parison is expanded to be in close contact with the cavity (not shown) of the molding die 3 and hollow molded into a hollow molding. It has become. The air blowing nozzle 8 comprises a nozzle body, a cutting sleeve, and a nozzle portion at the tip. The cutting sleeve has an outer peripheral edge that cooperates with the inner peripheral edge of the counter plate located at the nozzle driving inlet of the molding die 3 to shear the surplus portion of the parison cut from the above-mentioned parison cut from the molding die 3 It is designed to be cut off and generated as a bounce.

  The molded hollow molded article is conveyed out of the molding apparatus by a product take-out apparatus (not shown).

  FIG. 3 shows an enlarged side view of the mold clamping device of the hollow molding apparatus shown in FIG. As shown in FIGS. 1 and 2 and as shown in FIG. 3, the molding die moving apparatus 10 includes a pair of guide rails 11A and 11A laid apart on the base 9 and a guide member on the guide rails 11A and 11A. It comprises a movable base 12 slidably provided via 11B, a ball screw 13 for reciprocating the movable base 12 along the guide rails 11A and 11A, and a servomotor 14 for movement.

  The mold clamping device 4 is configured as described below.

  The mold clamping device 4 is also provided on the above-mentioned base 9, and three tie bars 15, 16, 17 are inserted and supported in the movable triangle 12 in an inverted triangle arrangement in the front view of FIG. , 16 and 17, the front support plate 18 and the rear support plate 19 are screwed with nuts. A bracket 20 attached to the front platen 5 is rotatably supported by a shaft 21 at an upper end portion of the front support plate 18. Slide collars 22 and 23 are provided below the front platen 5, and the tie bar 15 is slidably inserted into the slide collar 22 and the tie bar 16 is slidably inserted into the slide collar 23.

  The rear platen 6 is also provided with slide collars 24 and 25 at its lower part, and the tie bar 15 is slidably inserted into the slide collar 24 and the tie bar 16 is slidably inserted into the slide collar 25. The slide collars 22 and 25 are respectively provided with a bracket, and a first rack member 28 is provided on the bracket 26 provided on the slide collar 22 so as to extend in the horizontal direction. Although a bracket provided on the slide collar 25 is not shown, a second rack member 29 extends horizontally in parallel to the first rack member 28 on the bracket.

  Each of the rack members 28 and 29 is rotatably supported by the movable table 12 and is engaged with a pinion (not shown) so as to face each other. By moving in the left and right direction and in the opposite direction, the front platen 5 and the rear platen 6 are respectively moved toward the parting line located between the two platens.

  The clamping drive mechanism 30 forming the main part of the clamping device 4 is, as shown in FIG. 3, of the pair of first link arm 31 and second link arm 32 between the rear platen 6 and the rear support plate 19. Opening and closing of the molding die 3 and clamping are performed by extension and bending.

  One end of the first link arm 31 is rotatably coupled to the bracket 33 attached to the rear platen 6 via the shaft 34, and the other end is one end in the longitudinal direction of the rotor 35 formed in a substantially rhombus shape. It is rotatably coupled to the part via a shaft 36. The second link arm 32 has one end rotatably coupled to the other end in the longitudinal direction of the rotor 35 via a shaft 37.

  The rotor 35 is rotatably supported by the slide block 38 by a drive shaft 39. The slide block 38 is mounted upright on slide collars 40 and 41 fitted in the tie bars 15 and 16, respectively. As shown in FIG. 1, an output shaft 42 a of a mold clamping servomotor 42 which is an example of a mold clamping electric motor is coupled to a drive shaft 39 of the rotor 35 via a joint (not shown). The mold clamping servomotor 42 is fixed to the slide block 38 via a reduction gear (not shown). As the mold clamping electric motor, it is preferable to use one having easy rotation control like the mold clamping servomotor 42, but the invention is not limited thereto.

  The other end of the second link arm 32 is coupled to the biasing mechanism 43 of the clamping device 4. That is, the other end of the second link arm 32 is rotatably supported by a flat U-shaped bracket 44, and one end of the shaft 45 is fixed to the bracket 44. The shaft 45 is axially movably inserted into a hollow cylinder 46 provided at the upper end portion of the rear support plate 19 via a bush (not shown).

  In the cylinder 46, a plurality of disc springs 47 are accommodated in the shaft 45 while being resiliently pressed by the collar 45a fitted to the shaft 45 by the disc spring pressurization adjusting nut 48. At a rear portion of the disc spring 47, a retaining bush (not shown) fixed to the rear support plate 19 receives a restoring force of the disc spring 47. The plurality of disc springs 47 are disposed in a state in which the plurality of disc springs 47 are partially overlapped and in a state in which concave faces are combined and combined such that the overlapped ones can be compressed.

  As shown in FIGS. 2 and 4, the mold clamping servo amplifier 51 is connected to the mold clamping servo motor 42, and the servo controller 52 is connected to the mold clamping servo amplifier 51. Furthermore, a programmable logic controller (hereinafter, abbreviated as PLC) 53 is connected to the servo controller 52. The PLC 53 is connected to an operation screen 49 that functions as an operation panel of the operation panel.

  The mold clamping servo amplifier 51, the servo controller 52, and the PLC 53 constitute a control device 50 of the mold clamping servo motor 42. The control device 50 controls the normal drive control at the time of mold closing and mold opening of the molding die 3 by the mold clamping device 4 and at the time of mold clamping torque at the time of mold closing operation of the molding die 3 by the mold clamping device 4 It has a function of monitoring and executing torque abnormality processing when the mold clamping torque is abnormal.

  Specifically, in the control device 50, the torque waveform of the mold clamping servomotor 42 at the time of the normal operation of mold closing is acquired in advance and stored in the PLC 53 as a torque reference waveform. On the other hand, in the PLC 53, every time the mold closing operation of the molding die 3 is performed by the mold clamping device 4, an actual torque waveform of the mold clamping servo motor 42 at the mold closing operation (hereinafter, actual torque at the mold closing operation (Referred to as “waveform”) and the torque reference waveform, and when the timing of rising (rising) of the actual torque waveform at the mold closing operation is earlier than the torque reference waveform, the torque abnormality processing Control is performed to stop the clamping servo motor 42 via the controller 52 and the clamping servo amplifier 51. The setting time is a time arbitrarily set in the PLC 53 by the operation on the operation screen 49, and is determined in consideration of the mold closing speed, the distance of the low speed operation, the thickness of the object to be detected as foreign matter, the repetition accuracy of the operation, etc. Be done.

  Here, in addition to a method of acquiring in advance the torque waveform of the mold clamping servo motor 42 at the time of normal operation of mold closing and storing it in the PLC 53 as a torque reference waveform, comparison between the torque reference waveform and the actual torque waveform at the mold closing operation The details of the torque coefficient will be described later, but any torque waveform can be obtained from the correlation with the measured current value of the mold clamping servo motor 42. The torque value is a value when the rated torque of the mold clamping servo motor 42 is 100%. In the normal operation mode, the first link arm 31 and the second link arm 32 become linear when the mold clamping device 4 clamps the molding die 3 and clamps the parison, as shown in FIG. The plurality of disc springs 47 in the cylinder 46 shown in FIG. 6 are bent to a set compression amount, and a prescribed clamping force is generated.

  In the hollow molding apparatus configured as described above, the torque monitoring of the mold clamping servomotor 42 including the torque abnormality processing is performed in the procedure shown in FIG. 5 along with the start of the molding operation for the purpose of molding a specific molded product.

  That is, following the start of the molding operation in step S1 of FIG. 5, it is determined in step S2 whether non-defective conditions of the molded product are set. If the determination result in step S2 is "NO", that is, if the non-defective condition of the molded article is not set, setting of the non-defective condition of the molded article is prompted in step S3.

  If the determination result in step S2 is "YES", that is, if the non-defective condition of the molded article is set, the process proceeds to the next step S4, and "normal" on the operation screen 49 shown in FIG. Press and operate the "Torque waveform acquisition of mold clamping servomotor at the time of operation" switch.

  In the next step S5, n molding cycles for molding a specific molded product are repeated independently of the torque management function described above, and in each case, the actual torque waveform of the mold clamping servo motor 42 is PLC53. get. Then, these actual torque waveforms are regarded as torque waveforms of the mold clamping servo motor 42 at the time of normal operation, and an average value of the actual torque waveforms for n times is calculated. The calculated torque waveform average value of the mold clamping servomotor 42 at the time of normal operation calculated is stored in the PLC 53 as a torque reference waveform. The torque reference waveform is used as a reference value of the mold clamping servomotor 42 torque waveform in the (n + 1) th and subsequent molding cycles (molding shots). The torque monitoring function of the mold clamping servomotor 42 including the above-described torque abnormality processing becomes effective for the first time by storing and setting the torque reference waveform.

  Subsequently, in the next step S6, the process shifts to the (n + 1) th and subsequent molding cycle operations. In the (n + 1) th and subsequent molding cycles (molding shots), when the mold closing operation by the mold clamping device 4 is started based on the activation of the mold clamping servo motor 42 as in step S7, in the next step S8, Each time, the actual torque waveform of the clamping servomotor 42 is acquired by the PLC 53, and compared with the torque reference waveform stored and set previously.

  In the next step S9, it is determined whether or not the timing of rising (rising) of the actual torque waveform at mold closing is earlier than a predetermined time as compared to the torque reference waveform. In addition, the preset setting time said here is the time arbitrarily decided by operation by the operation screen 49 as stated above.

  If the result of the determination in step S9 is "NO", that is, if the timing of the rise (rise) of the actual torque waveform at mold closing is not earlier than the timing of the rise of the torque reference waveform, as in step S10. After completing the mold closing operation, the corresponding molding cycle operation is continued as in step S10. Then, the processing from step S6 to step S11 is repeated unless it is determined that the torque is abnormal at the time of mold closing.

  On the other hand, if the result of the determination in step S9 is "YES", that is, if the timing of rise of the actual torque waveform at the time of mold closing is earlier than a predetermined set time as compared with the timing of rise of the torque reference waveform. As the torque abnormality processing at the time of mold closing, the mold closing operation is immediately stopped as in step S12, and then the mold opening operation of the molding die 3 is performed as in step S13. Furthermore, after stopping the entire hollow molding apparatus as in step S14, in the next step S15, foreign matter caught in the molding die 3 which is the cause of torque abnormality at the time of mold closing. The operator will manually perform the removal.

  FIG. 6 shows a torque reference waveform (indicated by a solid line in FIG. 6) which is a torque waveform at the time of normal operation after the mold closing operation by the mold clamping device 4 starts and an actual time at the mold closing operation when foreign matter is caught. It compares with a torque waveform (it shows with a broken line in FIG. 6). As is clear from the figure, in both of the torque waveforms, when the mold clamping force comes into effect after the mold closing operation starts, the waveform will rise sharply.

  In the torque reference waveform which is a torque waveform at the time of normal operation after the start of the mold closing operation shown by the solid line in FIG. 6, when the mold halves 3a and 3b of the forming mold 3 are closed and brought close to each other The parting surfaces of the half molds 3a and 3b come in contact with each other, and the mold closing progresses further and the mold clamping force starts to be applied. As a result, as shown in FIG. 6, the torque of the mold clamping servomotor 42 rises sharply.

  On the other hand, in the actual torque waveform shown by a broken line in FIG. 6, for example, when foreign matter adheres to the parting surfaces of the half molds 3a and 3b forming the mold 3, both parting surfaces Since the foreign matter is crushed before the contact, the timing at which the torque of the mold clamping servo motor 42 sharply rises is earlier than the reference waveform.

  And in the example of FIG. 6, while the timing of rise of the actual torque waveform (dotted line) at the time of mold closing operation at the time of foreign object biting is about 80 milliseconds, the timing of rise of the torque reference waveform (solid line) Is about 90 milliseconds, and it can be seen that the rise of the actual torque waveform at the time of catching a foreign object is about 10 milliseconds earlier than the torque reference waveform. Therefore, the time corresponding to the time difference between the rising timings of both torque waveforms in FIG. 6, for example, about 5 to 10 milliseconds, is set in advance in PLC 53 by the operation on operation screen 49 of FIG. It shall be done.

  Here, the molding cycle operation at the time of normal operation in the above-mentioned hollow molding apparatus is as follows.

  That is, the molten synthetic resin extruded from the extruder 1 to the die head 2 is discharged and suspended as two parisons through the resin passage in the die head 2. These parisons enter the mold-opened mold 3 as shown in FIG. 3, and the mold 3 is clamped and clamped by driving the mold clamping device 4, and the upper part of the parison is shown in FIG. It cut | disconnects with cutters, such as a hot cutter abbreviate | omitted, and is made to exist in the shaping | molding die 3. As shown in FIG. At the time of mold closing prior to this parison cutting, the monitoring function of the mold closing torque described above is exhibited each time, and the processing after step S6 in FIG. 5 is executed.

  Subsequently, the molding die 3 is moved to the driving device 7, and the two parisons embedded in the molding die 3 are positioned directly below the two air blowing nozzles 8 of the driving device 7, and each parison is Each air blowing nozzle 8 is lowered and driven in, compressed air is blown into the parison from the air blowing nozzle 8, and each parison is expanded to be in close contact with the cavity of the molding die 3 and blow molded into a hollow molded article.

  The hollow molded product is suspended from the air blowing nozzle 8 together with the upper flash generated when the air blowing nozzle 8 is driven in, after the molding die 3 is opened and moved to the lower side of the die head 2 again.

  Then, a molded product holder (not shown) provided on the side of the molding die 3 grips the hollow molded product just molded in conjunction with the movement of the molding die 3 for introducing the next hanging parison.

  Then, the air blowing nozzle 8 ascends, and the upper beam attached to the air blowing nozzle 8 is removed at the time of the ascent. The air blowing nozzle 8 is further raised to return to the original position.

  On the other hand, the hollow molded article gripped by the molded article holder is held by a molded article take-out device (not shown) and released again at the timing of mold opening of the molding die 3 and then by the molded article take-out device It moves to a predetermined take-out position and moves out of the molding apparatus. According to such a hollow molding method, the above-described steps are repeated to mold and take out the hollow molded article.

  As described above, according to the hollow molding apparatus according to the present embodiment, at the time of the mold closing operation, even if a molded product or a burr at the time of the previous molding shot remains at the time of mold closing even if it remains temporarily in the molding die 3 It is possible to determine an abnormality from the torque waveform before setting mold clamping force is applied to the forming mold 3 and to stop the forming machine at that time.

  That is, the actual torque waveform at the time of mold closing operation is monitored for each shot, and the mold clamping servomotor 42 is stopped as abnormality processing when the rise timing of the actual torque waveform is earlier than the rise timing of the torque reference waveform. As a result, it is possible to prevent the mold 3 from being subjected to an excessive clamping force more than the setting, and damage to the mold 3 can be prevented in advance and easily.

  In addition, since the set time for abnormality judgment can be arbitrarily set and changed, detection accuracy according to molding can be determined such as molding machine operating conditions such as mold closing speed and distance of low speed operation, foreign object detection accuracy, etc. become.

  Here, as the processing of step S5 in FIG. 5, the actual torque waveform of the mold clamping servomotor 42 at the time of normal operation is acquired n times, and the average value of the n actual torque waveforms is stored as the torque reference waveform. It is like that. Instead of this, for example, when the reliability immediately after the start of the forming operation is high, the actual torque waveform may be obtained only once and used as the torque reference waveform.

3 ... molding die 4 ... mold clamping device 42 ... mold clamping servomotor (mold clamping electric motor)
50: Control device 51: Mold clamping servo amplifier 52: Servo controller 53: Programmable logic controller (PLC)

Claims (4)

For the mold clamping device that controls the mold closing and mold opening operations of the molding die, the torque waveform at the time of normal operation of the mold clamping electric motor is acquired in advance as a torque reference waveform
Every time the mold clamping device performs a mold closing operation, the actual torque waveform at the time of the mold closing operation of the mold clamping electric motor is compared with the torque reference waveform,
A hollow molding method comprising stopping the operation of the clamping electric motor as torque abnormality processing when the timing of rising of the actual torque waveform is earlier than the torque reference waveform.   The operation of the clamping electric motor is stopped as torque abnormality processing when the timing of rise of the actual torque waveform is earlier than the timing of rise of the torque reference waveform by a predetermined time or more. The hollow molding method described in 4. The mold clamping device that controls the mold closing and mold opening operations of the molding die is provided with a control device that monitors torque during mold closing operation of the mold clamping electric motor and executes torque abnormality processing,
The controller is
While acquiring the torque waveform at the time of normal operation of the mold clamping electric motor as a torque reference waveform in advance,
Every time the mold clamping device performs a mold closing operation, the actual torque waveform at the time of the mold closing operation of the mold clamping electric motor is compared with the torque reference waveform,
A hollow molding apparatus characterized in that the operation of the clamping electric motor is stopped as torque abnormality processing when the timing of rising of the actual torque waveform is earlier than the torque reference waveform. The controller is
The operation of the mold clamping electric motor is stopped as torque abnormality processing when the timing of rise of the actual torque waveform is earlier than the timing of rise of the torque reference waveform by a predetermined time or more. The hollow molding apparatus according to claim 3.

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