JP2004314492A - Mold clamping device of injection molding machine or the like and core backing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the mold clamping device of an injection molding machine or the like capable of performing core backing operation without additionally providing a ball screw and a servomotor for driving the ball screw. <P>SOLUTION: In the mold clamping device wherein a movable platen 2 having a movable mold 4 through a tie bar 5 is provided to a fixed platen 1 having a fixed mold 3 to be moved by a mold opening and closing servomotor 27 and a mold clamping half nut 33 for locking the movement of the movable platen at a predetermined position is provided while a hydraulic mold clamping cylinder 11 for permitting the insertion of the piston part provided to the tie bar to allow the tie bar to advance and retreat is further provided, a ball screw 19 for moving the movable platen through the tie bar and a half nut locating and core backing servomotor 17 for driving the ball screw are provided to the fixed platen. At the time of core backing of an injection molding process, the servomotor is driven to perform the core backing of the movable mold through the movable platen by the ball screw. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold clamping apparatus such as an injection molding machine for molding a molded product by injecting a molten resin into an injection mold and a core back method.
[0002]
[Prior art]
A mold clamping device such as an injection molding machine that molds a molded product by injecting molten resin into an injection molding die has a fixed plate with a fixed die attached and a moving die attached to this fixed plate via a tie bar. , A movable platen that can move forward and backward with respect to the fixed mold.
[0003]
The fixed board is provided with a hydraulic clamping cylinder for moving the tie bar forward and backward, and a tie bar sliding servomotor for moving the tie bar forward and backward. The moving plate is moved forward and backward on the tie bar by the mold opening / closing servomotor, and the moving plate is locked to the tie bar at a predetermined position by the mold clamping half nut. Then, in the injection pressing step, the hydraulic mold clamping cylinder is driven to press the fixed mold and the movable mold (for example, see Patent Document 1).
[0004]
Further, a fixed plate having a fixed die attached thereto, a movable die attached to the fixed plate via a tie bar, and a movable plate capable of moving forward and backward with respect to the fixed die, and a fitting protrudingly provided on the movable plate. A mold clamping ram having an insertion portion, and a hydraulic clamping cylinder for inserting and retracting the insertion portion of the clamping ram so as to be able to advance and retreat are provided. The fixed die and the movable die are pressed by moving the movable plate through the movable plate (see, for example, Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 10-296739
[Patent Document 2]
JP-A-6-182838
[Problems to be solved by the invention]
Meanwhile, Patent Documents 1 and 2 disclose that the tie bar is advanced and retracted by a tie bar slide servomotor, the phase of the mold clamping half nut and the thread portion of the tie bar are adjusted, and the mold clamping half nut and the thread portion of the tie bar mesh. After that, the hydraulic mold clamping cylinder is driven to press the fixed mold and the movable mold.
[0008]
Further, after the molten resin containing the foaming material is injected from the injection molding machine into the cavity formed by the fixed mold and the moving mold and filled, the moving mold is moved to the fixed mold with the progress of the foaming of the foamed material. To perform a core back operation to expand the cavity.
[0009]
Conventionally, since this core back operation is performed by controlling the hydraulic pressure of the hydraulic mold clamping cylinder, there is a problem that the positional accuracy varies and the dimensional accuracy of the molded product varies.
[0010]
Therefore, there is a device that additionally includes a ball screw and a servomotor for driving the ball screw on the moving board, thereby performing a core back operation. However, in this case, the apparatus is replaced each time the mold is replaced, or a ball screw and a servo motor for driving the ball screw are provided for each mold, which causes an increase in cost.
[0011]
The present invention has been made in view of the above circumstances, and an object of the present invention is to perform a core back operation without additionally providing a ball screw and a servomotor for driving the ball screw. An object of the present invention is to provide a mold clamping device such as an injection molding machine and a core back method that can improve the positional accuracy.
[0012]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention is characterized in that a fixed plate on which a fixed die is mounted, a movable die is mounted on the fixed plate via a tie bar, and the movable plate is moved forward and backward with respect to the fixed die. A freely movable moving plate, a mold opening / closing servomotor for moving the moving plate forward and backward on the tie bar, a mold clamping half nut for locking the movement of the moving plate at a predetermined position, and a piston provided on the tie bar In a mold clamping device such as an injection molding machine including a hydraulic mold clamping cylinder for inserting and closing a portion to move a tie bar forward and backward, a feed screw for moving the moving plate to the fixed plate via the tie bar, and driving the feed screw. A half-nut positioning / core-back servomotor is provided, and at the time of core-back in the injection molding process, the half-nut positioning / core-back servomotor is driven to feed the core. Characterized by core back moving mold through the movable platen by.
[0013]
A second aspect of the present invention provides a fixed plate on which a fixed die is mounted, a movable die mounted on the fixed plate via a tie bar, and a movable plate which can move forward and backward with respect to the fixed die. A mold opening / closing servomotor for moving forward and backward, a mold clamping half nut for locking the movement of the moving plate at a predetermined position, and a mold clamping ram having a fitting portion protruding from the moving plate. In a mold clamping device such as an injection molding machine comprising a hydraulic mold clamping cylinder for removably inserting and inserting a fitting portion of the mold clamping ram, the movable platen is moved to the hydraulic mold clamping cylinder via the mold ram. A feed screw to be driven and a servomotor for driving the feed nut and a half nut positioning and core back, and driving the half nut positioning and core back servo motor during the core back in the injection molding step to drive the feed screw. Characterized by core back moving mold through the movable platen by means of screws.
[0014]
According to a third aspect of the present invention, there is provided a method of core-backing the movable mold using a mold clamping device such as an injection molding machine according to the first or second aspect, wherein a molten resin containing a foam material is injected from an injection nozzle of the injection molding machine. After filling the cavity formed by the fixed mold and the movable mold, the half-nut positioning and core-back servomotor is driven to move the movable mold through the movable platen by the feed screw to move the core mold back to the core. It is characterized by doing.
[0015]
According to the above configuration, when the molten resin containing the foaming material is injected from the injection nozzle of the injection molding machine and filled in the cavity formed by the fixed mold and the movable mold, the molten resin foams in the cavity. . As the molten resin foams, the half-nut positioning and core-back servomotor is driven and the moving die is core-backed through the moving plate with the feed screw, and the cavity expands to the size of the molded product and expands. The filled cavity is filled with the molten resin.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 shows a first embodiment, and FIG. 1 is a vertical sectional side view of a mold clamping device of an injection molding machine. In the figure, 1 is a fixed board, and 2 is a moving board. A fixed die 3 is mounted on the fixed platen 1, and a movable die 4 facing the fixed die 3 is mounted on the movable platen 2. The fixed platen 1 is provided with a plurality of tie bars 5 protruding therefrom, and the movable platen 2 moves on these tie bars 5 so as to be able to advance and retreat.
[0018]
The fixed die 3 is provided with a nozzle touch surface 7 that is joined to an injection nozzle 6 of an injection molding machine (not shown). The nozzle touch surface 7 is connected to the fixed die 3 and the movable die 4 via a resin passage 8. And a cavity 9 provided therebetween. Further, the fixed platen 1 is provided with an opening 10 through which the injection nozzle 6 is opened and retracted.
[0019]
A hydraulic mold clamping cylinder 11 is provided at a portion of the fixed plate 1 connected to the tie bar 5. A piston portion 12 provided integrally with the base end of the tie bar 5 is fitted into the hydraulic mold clamping cylinder 11, and the interior of the hydraulic mold clamping cylinder 11 has a mold clamping side chamber 13a and a mold opening side chamber with the piston portion 12 interposed therebetween. 13b.
[0020]
Further, the base end of the piston portion 12 penetrates through the partition wall 14 of the hydraulic mold clamping cylinder 11 and protrudes into the positioning box 15. The positioning box 15 is provided with a half-nut positioning and core-back servomotor (hereinafter, referred to as a first servomotor) 17. A bearing 18 is provided on the back of the positioning box 15 coaxially with the piston portion 12, and a screw shaft 20 of a ball screw 19 as a feed screw is rotatably supported on the bearing 18. The proximal end of the screw shaft 20 protrudes from the back of the positioning box 15, and a driven pulley 21 is fitted to this protruding portion.
[0021]
The servo motor 17 is provided with a drive pulley 22, a timing belt 23 is stretched between the drive pulley 22 and the driven pulley 21, and the screw shaft 20 of the ball screw 19 rotates. A screw portion 24 is provided at the tip of the screw shaft 20, and the screw portion 24 is screwed with a nut portion 25 fitted to the shaft center of the piston 12. Therefore, the rotational motion of the screw shaft 20 is converted into the linear motion via the nut 25 by the ball screw 19.
[0022]
The fixed platen 1 is provided with a plurality of mold opening / closing servomotors (hereinafter, referred to as second servomotors) 27 via brackets 26. The rotary shaft 28 of the servomotor 27 is provided with a screw portion 29. A nut portion 30 is screwed into the screw portion 29, and the nut portion 30 is fixed to the moving platen 2 to form a feed screw 31 as a ball screw. Accordingly, when the screw portion 29 is rotated by the driving of the second servomotor 27, the movable platen 2 advances and retreats with respect to the fixed platen 1 via the nut portion 30, and the movable die 4 moves with respect to the fixed die 3. Is designed to open and close the mold.
[0023]
The tie bar 5 projects through the moving platen 2, and an outer peripheral surface of the tie bar 5 is provided with an engagement groove 5 a formed of a thread or an annular groove. Further, a mold clamping half nut 33 which is opened and closed by an opening / closing cylinder 32 and is engaged with and disengaged from the engagement groove 5 a of the tie bar 5 is provided on the rear side of the movable platen 2.
[0024]
Next, the operation of the mold clamping device of the injection molding machine configured as described above will be described. When the fixed mold 3 and the movable mold 4 are attached and the mold thickness is adjusted, the engagement half of the mold clamping half nut 33 and the engagement groove 5 a of the tie bar 5 is released by the opening / closing cylinder 32.
[0025]
Next, a mold closing operation is performed by driving the second servomotor 27. In this case, at the mold closing limit, the mold clamping half nut 33 is closed by the opening / closing cylinder 32, meshing with the engagement groove 5 a of the tie bar 5, and the movable platen 2 is engaged with the tie bar 5.
[0026]
At this time, the mold clamping half nut 33 and the engagement groove 5a of the tie bar 5 need only be properly engaged with each other. However, if the engagement does not occur due to a shift in both pitches, the first servomotor 17 is driven. That is, by driving the first servomotor 17, the ball screw 19 causes the tie bar 5 to slightly advance through the piston portion 12, and the mold clamping half nut 33 and the engagement groove 5a of the tie bar 5 are properly engaged with each other. Then, the first servomotor 17 is stopped.
[0027]
At this time, the position of the tie bar 5 is read and stored by position detecting means (not shown). In the subsequent molding operation, the first servomotor 17 is controlled such that the tie bar 5 is always at this position at the limit of the advance of the mold by the moving platen 2. Thus, the mold thickness adjusting operation is completed.
[0028]
As described above, after the engagement position of the mold clamping half nut 33 is adjusted, the movable platen 2 is advanced by driving the second servomotor 27, and after reaching the arbitrary position near the advance limit. The first servomotor 17 is driven to start retreating the tie bar 5 by the ball screw 19 (to the right in the figure), and the speeds of the second servomotor 27 and the first servomotor 17 are controlled so that their relative speeds are controlled. Are synchronized (that is, the relative speed is set to 0). Then, when the moving speed of the moving platen 2 and the tie bar 5 are synchronized and the relative speed at the specific position is 0, the mold clamping half nut 33 is closed to engage with the engagement groove 5a of the tie bar 5.
[0029]
After the engagement position of the mold clamping half nut 33 has been adjusted in this manner, an injection molding process including a mold clamping operation is started. First, when the second servomotor 27 is driven to move the moving platen 2 forward, and when the moving platen 2 reaches an arbitrary position near the mold closing limit, the moving platen 2 is located to the left from the previously stored position. The tie bar 5 starts retreating (rightward in the figure) by driving the first servo motor 17, and controls the speeds of the respective servo motors 17 and 27 to calculate the relative speed between the movable platen 2 and the tie bar 5. (That is, the relative speed is set to 0).
[0030]
Then, when the moving speed of the moving platen 2 and the tie bar 5 in the right direction is synchronized at a predetermined position, the engagement between the mold clamping half nut 33 and the engagement groove 5a of the tie bar 5 is detected. If the engagement is at an appropriate position, the mold clamping half nut 33 is closed and the engagement groove 5a of the tie bar 5 is engaged while maintaining the speed control so that the relative speed becomes zero. When the engagement is completed and the movable platen 2 reaches the mold closing limit, the position of the tie bar 5 is read by a position detector (not shown) and compared with the position of the tie bar 5 stored at the time of the mold thickness adjustment described above. If the comparison results match, the mold clamping / injection press operation starts.
[0031]
After the stationary mold 3 and the movable mold 4 are clamped, when a molten resin containing a foam is injected from the injection nozzle 6 of the injection molding machine, the molten resin is filled into the cavity 9 via the resin passage 8. . Since the molten resin containing the foaming material filled in the cavity 9 foams in the cavity 9, the first servomotor 17 is driven as the foaming proceeds, and the tie bar 5 is advanced by the ball screw 19 (leftward in the figure). ), And the movable mold 4 performs a core-back operation with respect to the fixed mold 3 via the movable platen 2.
[0032]
Therefore, the cavity 9 is expanded, and after the molten resin including the foaming material foams in the expanded cavity 9 and the movable mold 4 core-backs by a predetermined amount, the first servomotor 17 is stopped. Then, a molded product is formed through a pressure holding and cooling process.
[0033]
After forming the molded product, the mold opening process is started, and while the pressurized oil in the mold opening side chamber 13b of the hydraulic mold clamping cylinder 11 is introduced, the second servomotor 27 is driven, and the moving platen 2 is advanced by the ball screw 31 ( When this is performed (left direction in the figure), the fixed mold 3 and the movable mold 4 are opened, and the molded product can be taken out. Further, the engagement between the mold clamping half nut 33 and the engagement groove 5a of the tie bar 5 is released during the mold opening. At the same time, the first servomotor 17 is driven in the reverse direction to move the tie bar 5 to the left, completing one cycle of injection molding.
[0034]
According to the first embodiment, the position accuracy at the time of molding is improved by driving with the first servomotor and the ball screw during the core back operation in the injection molding process. In addition, since the half-nut positioning servomotor is also used for the core back operation, it is not necessary to add a servomotor to the moving die or the moving plate, and the cost can be reduced.
[0035]
FIG. 2 shows a second embodiment, in which the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. A hydraulic mold clamping cylinder 40 is provided on the back side of the movable platen 2 supported by the plurality of tie bars 5. The hydraulic mold clamping cylinder 40 is provided with a hydraulic chamber 41 that opens on the back side of the moving platen 2, and a mold clamping ram 42 is fitted into the hydraulic chamber 41 so as to be able to advance and retreat. The tip of the mold clamping ram 42 is connected to the moving platen 2.
[0036]
The hydraulic mold clamping cylinder 40 is provided with a stepped through hole 43 in series with the hydraulic chamber 41, and a screw shaft 45 constituting a feed screw 44 as a ball screw is inserted into the through hole 43 so as to be able to advance and retreat. . A flange 45 a is provided at one end of the screw shaft 45, and the flange 45 a is connected to the mold clamping ram 42. The other end of the screw shaft 45 protrudes rearward of the hydraulic mold clamping cylinder 40, and a screw portion 46 is formed at the protruding portion. A nut portion 47 of the ball screw 44 is screwed into the screw portion 46, and a driven pulley 48 is integrally fitted to the nut portion 47.
[0037]
The hydraulic mold clamping cylinder 40 is provided with a half nut positioning and core back servomotor (hereinafter, referred to as a first servomotor) 50 by a bracket 49. The first servomotor 50 is provided with a driving pulley 51, and a timing belt 52 is stretched between the driving pulley 51 and the driven pulley 48.
Accordingly, the nut portion 47 of the feed screw 44 is rotated by the driving of the first servomotor 50, and the rotation of the nut portion 47 is converted into a linear motion, and the screw shaft 45 moves forward and backward in the axial direction. .
[0038]
Next, the operation of the mold clamping device of the injection molding machine configured as described above will be described. After the stationary mold 3 and the movable mold 4 are clamped as shown in FIG. 2 by the same operation as in the first embodiment, the molten resin containing the foamed material is injected from the injection nozzle 6 of the injection molding machine. The molten resin is filled into the cavity 9 via the resin passage 8. Since the molten resin containing the foaming material filled in the cavity 9 foams in the cavity 9, the first servo motor 50 is driven as the foaming progresses, and the ball screw 44 moves the mold clamping ram 42 leftward in the figure. The movable mold 4 performs a core-back operation with respect to the fixed mold 3 via the movable board 2.
[0039]
Therefore, the cavity 9 is expanded, and after the molten resin including the foaming material foams in the expanded cavity 9 and the moving mold 4 core-backs by a predetermined amount, the first servomotor 50 stops. Then, a molded product is formed through a pressure holding and cooling process.
[0040]
When the second servomotor 27 is driven and the movable platen 2 is moved leftward in the figure by the ball screw 31 after the molded product is formed, the fixed mold 3 and the movable mold 4 are opened, and the molded product is opened. Can be taken out. Further, the engagement between the mold clamping half nut 33 and the engagement groove 5a of the tie bar 5 is released during the mold opening. At the same time, the first servomotor 50 is driven in the reverse direction to move the mold clamping ram 42 to the left, completing one cycle of the injection molding.
[0041]
According to the second embodiment, the position accuracy at the time of molding is improved by driving with the first servomotor and the ball screw during the core back operation in the injection molding process.
In addition, since the half-nut positioning servomotor is also used for the core back operation, it is not necessary to add a servomotor to the moving die or the moving plate, and the cost can be reduced.
[0042]
In the first and second embodiments, the pulley and the belt are used for the power transmission between the first servomotor and the ball screw. However, the power may be transmitted by a gear, and the power is not limited to the ball screw. Alternatively, a feed screw mechanism such as a screw or a planetary roller screw may be used as long as it converts a rotational motion into a linear motion.
[0043]
Although the mold clamping device of the injection molding machine has been described, the invention can be similarly applied to, for example, a die casting machine or a press machine.
[0044]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements in an implementation stage without departing from the scope of the invention. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, components of different embodiments may be appropriately combined.
[0045]
【The invention's effect】
As described above, according to the present invention, the core back operation can be performed without additionally providing a ball screw and a servomotor for driving the ball screw, and there is an effect that cost can be reduced and positional accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a vertical sectional side view of a mold clamping device of an injection molding machine showing a first embodiment of the present invention.
FIG. 2 is a vertical sectional side view of a mold clamping device of an injection molding machine showing a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fixed board, 2 ... Moving board, 3 ... Fixed mold, 4 ... Moving mold, 5 ... Tie bar, 11 ... Hydraulic mold clamping cylinder, 17 ... 1st servomotor (half nut positioning and core back servomotor) ), 19: Ball screw (feed screw), 27: Second servo motor (servo motor for opening and closing the mold), 33: Half nut for clamping, 40: Cylinder for hydraulic clamping, 44: Ball screw (feed screw) , 50 ... 1st servo motor (half nut positioning and core back servo motor)

Claims (3)

A fixed plate having a fixed die attached thereto, a movable die attached to the fixed plate via a tie bar, and a movable plate capable of moving forward and backward with respect to the fixed die; and a mold opening and closing for moving the movable plate forward and backward on the tie bar. Injection molding comprising: a servo motor for locking, a mold clamping half nut for locking the movement of the moving plate at a predetermined position, and a hydraulic clamping cylinder for inserting and retracting a piston portion provided on the tie bar to advance and retract the tie bar. In a mold clamping device such as a machine,
The fixed platen is provided with a feed screw for moving the moving platen via the tie bar and a half-nut positioning and core-back servomotor for driving the feed screw. A mold clamping device for an injection molding machine or the like, wherein a back servomotor is driven to core-back a moving mold via the moving plate by the feed screw. A fixed plate having a fixed die attached thereto, a movable die attached to the fixed plate via a tie bar, and a movable plate capable of moving forward and backward with respect to the fixed die; and a mold opening and closing for moving the movable plate forward and backward on the tie bar. Servo motor, a mold clamping half nut for locking the movement of the moving plate at a predetermined position, a mold clamping ram having a fitting portion protruded from the moving plate, and a mold clamping ram. In a mold clamping device such as an injection molding machine comprising a hydraulic mold clamping cylinder for fittingly inserting and retracting the fitting portion,
The hydraulic mold clamping cylinder is provided with a feed screw for moving the movable platen via the mold ram and a half-nut positioning / core-back servomotor for driving the feed screw. A mold clamping device for an injection molding machine or the like, characterized in that a nut positioning and core-back servomotor is driven to core-back a moving die via the moving plate by the feed screw. A method of core-backing the movable mold using a mold clamping device such as an injection molding machine according to claim 1 or 2,
After injecting the molten resin containing the foaming material from the injection nozzle of the injection molding machine and filling the cavity formed by the fixed mold and the movable mold,
A core back method for a mold clamping apparatus such as an injection molding machine, characterized in that the half nut positioning and core back servomotor is driven to core back a moving die via the moving plate with the feed screw.

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