JP2001079915A - Mold opening safety device for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the coersive opening of a mold and thereby prevent the mold and a clamping device from being damaged, when it is difficult to open the mold for some reasons. SOLUTION: A mold opening/closing and moving operation of a movable platen 6 to a fixed platen 2 is performed by a hydraulic cylinder 9 fixed to an end plate 5 through a toggle mechanism 7. A hydraulic device 22 for actuating the hydraulic cylinder 9 is actuated through a connection with the controller 26 of a control means 24. The controller 26 opens/moves the movable platen 6 by a thrust based on a limiting value which is set by a limiting value setting means 27, and when the moving time reaches a set time by a limit time setting means 28, the judgement whether the mold-opening moving amount of the movable platen 6 detected by a position detector 25 reaches a reference stroke value set by a stroke setting means 29 is made. Based on the judgment results, the controller 26 stops the mold-opening action of the movable platen 6 or performs the actuation of an alarm generating means 30 or the reset to the mold-opening action by a routine thrust.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine for preventing an excessive mold opening force from acting on fixing means having a mold mounted on a mold mounting plate when the mold is opened in a mold clamping unit. And a safety device for opening the mold.

[0002]

2. Description of the Related Art Conventionally, a mold clamping unit of an injection molding machine has an end plate connected to a fixed plate (die mounting plate) fixed to a machine base by a tie bar, and is movable between the end plate and the fixed plate. A board (die mounting board) is supported movably in the axial direction along the tie bar, and the movable board is fixed directly or indirectly via a toggle mechanism by drive means such as a hydraulic cylinder provided on the end plate. The mold is moved forward and backward with respect to the board, and the mold fixed to the fixed board and the movable board by the fixing means is opened and closed and the mold is closed.
As a fixing means for fixing the mold to each mold mounting board,
A clamp that fixes the mold flange to the mold mounting plate with bolts, and a clamp that rotates the clamp lever supported by the mold mounting plate with the force of a cylinder, spring, etc., and tightens the mold flange to the mold mounting plate There is a device that uses a device, but in recent years, the latter is frequently used for the purpose of improving the efficiency of mold replacement work.

[0003] In the case of an injection molding machine, the volume of the molten resin injected into the mold shrinks when cooled and solidified, so that the interior of the mold may be in a vacuum state. Damage or sticking may occur, and the mold may not open with normal mold opening forces. For this reason, conventionally, the driving means of the movable platen performs the mold opening operation of the mold with a relatively large driving force setting from the start to the end of the mold opening corresponding to the various states and phenomena described above, and the molding operation is performed. It is to be continued.

[0004]

However, if the driving means of the movable platen performs the mold opening operation with a large driving force set as in the prior art, the vacuum condition in the mold and the damage to the slide portion of the mold are caused. In the event of a sticking phenomenon, the mold is forcibly opened with the maximum mold opening force, so the bolts in the mold fixing means are damaged, and the clamp lever of the clamp device and its support pins are damaged. Or the flange of the mold may be damaged.

Accordingly, the present invention provides an injection molding machine which prevents a mold from being forcibly opened when the mold is difficult to open for some reason, and prevents the mold and the clamp device from being damaged. It is an object of the present invention to provide a safety device for opening a mold. It is another object of the present invention to provide a mold opening safety device for an injection molding machine that has a simple structure and is easy to implement.

[0006]

According to a first aspect of the present invention, a movable plate is provided with a fixed plate and a movable plate, and the movable plate is moved toward and away from the fixed plate by a driving mechanism. A mold clamping unit configured to perform mold opening, mold closing and mold clamping attached to the fixed plate and the movable plate via fixing means, wherein the movable mechanism is driven by the driving mechanism when the mold is opened. Is provided with control means for restricting the thrust acting on the motor to below a preset limit value.

In the apparatus having the above structure, the movable plate is moved forward with respect to the fixed plate by the drive mechanism, the mold is clamped between them, and the molten resin is injected into the mold by the injection unit. . When the injection resin cools and solidifies in the mold, the movable platen moves backward and the mold is opened. When the mold is opened, the thrust of the movable platen by the driving mechanism is limited by the control means to a predetermined value or less, which is equal to or less than the strength of the fixing means for fixing the mold to the mold mounting board, so that the inside of the mold has resin. When a vacuum state is caused by the shrinkage, or when the slide portion of the mold is damaged or adhered, an excessive mold opening force is not forcibly applied to the mold. Therefore, damage to the components of the machine having the weakest strength is reliably prevented, and safety is ensured.

In the apparatus according to the first aspect, when the limit value of the thrust of the movable plate is set to be equal to or less than the strength of the fixing means (Claim 2), it is possible to fix the mold having the weakest strength. The means is not damaged, and the machine and the mold are prevented from being damaged.

[0009] In the apparatus according to claim 1 or 2, the control means can be configured to limit the thrust of the movable platen for a preset time limit after the mold opening of the movable platen is started ( Claim 3). In this configuration, the time until the operation of the guide pin of the mold coming out of the pin hole is completed,
Alternatively, the thrust of the movable platen is limited until the operation of the mold slide core or the like is completed, and the above operation is safely completed, and the mold opening operation is performed smoothly.

[0010] In the apparatus according to the third aspect, the control means is configured to stop the mold opening operation of the movable platen when the movable platen does not open to a preset position within the time limit. The movement of the movable platen is stopped immediately in response to the item 4) and the abnormality of the mold opening operation, and the safety of the machine is secured.

In the apparatus according to the third or fourth aspect, when the movable platen does not open the mold to a preset position within the time limit, the control unit operates the alarm generation means for notifying the abnormality of the mold opening. (Claim 5)
The required measures can be taken promptly by reliably knowing that the movable platen is open abnormally. 4. The apparatus according to claim 3, wherein, when the movable platen is opened to a preset position within a time limit, the movable platen is opened by a normal thrust when the mold opening amount exceeds the position. If it is configured to perform the operation (claim 6), the mold opening operation of the movable plate is quickly and reliably performed over the entire section of the mold opening process.

The apparatus according to any one of claims 1 to 6, wherein the control means includes: a time measuring means for measuring an elapsed time after the start of opening of the movable plate; and a start of opening of the movable plate. A position detector for detecting a later moving position, a limit value setting means for setting a limit value of a thrust when the movable platen is opened, and a time for holding a limit value of the thrust when the movable platen is opened. Time limit setting means, stroke setting means for setting a reference stroke value for opening movement of the movable platen, alarm generation means, and movable by operating the drive mechanism based on the limit value set by the limit value setting means. When the mold opening movement of the board is performed, and when the time measured by the timing means reaches the set time by the time limit setting means, the mold opening movement amount of the movable board detected by the position detector is determined by the stroke setting means. Judge whether the trooke value has been reached or not, and based on the judgment result, select the stop of the mold opening operation of the movable platen by the drive mechanism, the operation of the alarm generation means, and the return to the mold opening operation by normal thrust. (Claim 7). According to this configuration, the operation from the operation at the time of opening the movable plate to the completion of the mold opening is safely and accurately performed based on the set value set by each setting unit.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a mold clamping unit of a hydraulic injection molding machine. A fixed platen (die mounting plate) 2 of the mold clamping unit 1 is fixed to an upper portion on one side of a machine base 3. An end plate 5 connected to the fixed platen 2 by a tie bar 4 is supported on an upper portion on the other side of the mechanical base 3. The fixed plate 2 and the end plate 5
The movable plate (die mounting plate) 6 is provided between the tie bar 4
Is provided movably supported in the axial direction,
Further, the movable platen 6 is connected to the end plate 5 via a toggle mechanism 7. Then, the cross head 8 of the toggle mechanism 7 is fixed to the tip of a piston rod 10 of a hydraulic cylinder 9 fixed to the end plate 5, and the movable cylinder 6 is moved via the toggle mechanism 7 by operating the hydraulic cylinder 9. It moves forward and backward with respect to the fixed platen 2.

As shown in FIG. 2 and FIG. 3, the mold mounting surfaces 6a and 2a of the movable plate 6 and the fixed plate
The movable mold 11a and the fixed mold 11b are formed integrally with each other or are fixed by fastening the flanges 11e and 11f formed by connecting the mold base 11d with the bolts 11c with the fixing bolts 12. The above mold 11
As means for fixing a and 11b to the mold mounting plates 6 and 2,
Instead of directly fastening the flanges 11e and 11f to the mold mounting plates 6 and 2 with the fixing bolts 12, as shown in FIG.
Pressing bracket 1 fixed to mold mounting plates 6 and 2 with bolts 13
4, the flanges 11e and 11f may be fastened to the mold mounting plates 6 and 2.

Further, as shown in FIG. 5, a clamp lever 16 having a pin 15 is
5 and the flanges 11e, 11
The taper block 20 fixed to the tip of the rod 19 of the air cylinder 18 and the hook 21 are engaged with the base end of the clamp lever 16 so as to move forward and backward with respect to f. As a result, the clamp lever 16 moves forward with respect to the flanges 11e and 11f, and is
e, 11f may be tightened, and the structure may be configured to release the tightening and move backward.

The hydraulic cylinder 9 for operating the toggle mechanism 7 is connected via a hydraulic pipe to a hydraulic device 22 comprising a hydraulic source such as a hydraulic pump, an electromagnetic flow control valve, an electromagnetic pressure control valve, an electromagnetic direction switching valve and the like. ing. The hydraulic cylinder 9 and the hydraulic device 22 constitute a hydraulic drive mechanism (drive mechanism) 23. Mold clamping unit 1 of the above hydraulic injection molding machine
Is well known in the art.

Next, the control means 24 for controlling the mold opening operation in the mold clamping unit 1 having the above configuration will be described.
The controller 24 is connected to the hydraulic device 22 via an input / output interface, and is connected to a controller 26 connected to a position detector 25 for detecting a moving position of the movable platen 6 via an A / D converter. A limit value setting unit 27 connected to the controller 26 via an input interface for setting a limit value of a mold opening force of the movable platen 6; a limit time setting unit 28 for setting a time for holding the limit value. , And movable platen 6 holding the above-mentioned limit value
Setting means 2 for setting the reference stroke L1
9 and an alarm generating means 30 connected to the controller 26 via an output interface.

The controller 26 includes a timer (measuring means).
And a control program for controlling the overall operation of the injection molding machine, each set value input from the limit value setting means 27, the time limit setting means 28 and the stroke setting means 29, data necessary for arithmetic control, etc. And a central processing unit or the like that performs a required operation based on the time measured by the timer, the set values, the detected value of the position detector 25, and the machine based on the data, and controls the machine. A command is issued to the hydraulic device 22 so that the mold opening operation of the movable platen is performed as set, and a command is issued to the alarm generating means 30 to generate an alarm in a timely manner.

The limit value setting means 27 sets the limit value of the mold opening force of the movable platen 6 as the limit value of the hydraulic pressure acting on the hydraulic cylinder 9. , 12a is determined by the strength of the lowest strength component in the fixing means. That is, FIG.
In the case of the fixing means shown in FIG. 3, the value obtained by multiplying the tensile strength of the fixing bolt 12 or the bolt 11 c by the number of bolts is:
In the case of the fixing means shown in FIG. 4, the value obtained by multiplying the tensile strength of the bolt 13 by the number of bolts or the value obtained by multiplying the breaking strength of the holding metal 14 by the number of the metal fittings 14 is shown in FIG. In the case of the means, the safety factor is determined by referring to the value obtained by multiplying the shear strength of the pin 15 by the number of the pins 15 and the value obtained by multiplying the breaking strength of the clamp lever 16 by the number of the levers 16, respectively. Is set as the limit value of the mold opening force of the movable platen 6 and is converted into the hydraulic pressure acting on the hydraulic cylinder 9 in consideration of the magnification of the force by the toggle mechanism 7 to obtain the set value of the limit value. Note that the mold opening force of the movable platen 6 is a direction perpendicular to the mold mounting surface of the movable platen 6 (mold opening direction).
Means thrust acting on

The time limit setting means 28 sets the time for holding the limit value set by the limit value setting means 27. The time limit setting means 28 sets the movable platen 6 at a normal mold opening speed.
From the start of mold opening until the guide pin 11g of the mold 11b completely comes out of the guide hole 11h of the mold 11a, or the time when the operation of the slide core or the like is completed. And

At the time set by the time limit setting means 28, the stroke setting means 29 is equal to or equal to the amount of movement of the movable platen 6 from the start of mold opening at the speed of normal mold opening operation. A slightly larger movement amount (reference stroke value of mold opening) L1 is set, and when the mold opening amount is equal to or greater than the reference stroke value L1 of the movable platen 6, the limitation of the mold opening force (the limitation of the hydraulic pressure of the hydraulic cylinder).
Is released, and the normal mold opening force (thrust) is restored.

The alarm generating means 30 determines that the stroke of the movable platen 6 detected by the position detector 25 within the time set by the time limit setting means 28 is equal to the reference stroke value L1 set by the stroke setting means 29. Is not reached, an alarm lamp,
An abnormal state of the mold opening of the movable platen is notified by a buzzer or the like.

Next, the operation of the device configured as described above will be described. The hydraulic device 22 operates according to a command from the controller 26, and the rod 10 of the hydraulic cylinder 9 extends,
The movable platen 6 moves forward with respect to the fixed platen 2 via the toggle mechanism 7, and the molds 11 a and 11 b are interposed between the movable platen 6 and the fixed platen 2.
Is molded, molten resin is injected into the cavities of the molds 11a and 11b by an injection unit (not shown) to perform molding. Then, when the molded product in the cavity is solidified by cooling, the hydraulic device 22 is operated in reverse by the command of the controller 26, the rod 10 of the hydraulic cylinder 9 contracts, and the molds 11a and 11b are opened. (Step S1). At this time, the controller 26 instructs the hydraulic device 22 to switch the set oil pressure of the electromagnetic pressure control valve to the set value set in advance by the limit value setting means 27, so that the movable platen 6 is restricted by the hydraulic cylinder 9. It moves backward by driving force and opens the mold with limited thrust.

Further, the controller 26 determines whether or not the internal timer has started counting at the same time as the mold opening has started, and whether or not the counting time T2 of the timer has exceeded the time T1 set by the time limit setting means 28. It is determined (step S2), and if it has not elapsed, the current mold opening position (mold opening stroke) L2 of the movable platen 6 detected by the position detector 25 is the reference stroke set in advance by the stroke setting means 29. It is determined whether the value exceeds the value L1 (step S3). If it is determined that it has not exceeded, the movable platen 6 is retracted with the limited thrust to continue the mold opening movement (step S4).
The set hydraulic pressure of the electromagnetic pressure control valve is switched to release the restriction on the thrust of the movable platen 6, and the movable platen 6 is driven with a normal thrust when the mold opening amount is equal to or more than the reference stroke value L1 (step S5). .

In step S2, the timer time T2
Is the time T set by the time limit setting means 28
1 has passed, is the current mold opening position (mold opening stroke) L2 of the movable platen 6 detected by the position detector 25 exceeding the reference stroke value L1 preset by the stroke setting means 29? It is determined whether or not the movable platen 6 is driven with a normal thrust as in step S5 (step S6).
If not, the controller 26 determines that the mold opening operation is abnormal, and instructs the hydraulic device 22 to stop the operation of the hydraulic pump to stop the mold opening operation.
A command is issued to the alarm generation means 30 to generate an alarm for notifying the abnormality of the mold opening operation.

In the apparatus having the above-described structure, the thrust of the movable platen 6 at the time of starting the mold opening is limited to a predetermined value or less.
When the mold opening amount (reference stroke value L1) does not reach the set mold opening amount within the set time, the mold opening operation is determined to be abnormal, and the mold opening operation is stopped. Even if a vacuum is generated inside the molds 11a and 11b or the guide pin 11g of the mold 11b is damaged, no excessive mold opening force acts on the molds 11a and 11b, and the mold 11a , 11b and the fixing means for fixing the same to the mold mounting plates 2, 6 can be prevented from being damaged or the machine from being damaged.
When there is no abnormality in the mold opening, the movable platen 6 is driven by a normal thrust with the mold opening amount equal to or more than the reference stroke value L1, and thus the mold opening operation is quickly and smoothly repeated over the entire mold opening stroke. be able to.

In the above-described embodiment, the thrust of the movable platen 6 at the start of the mold opening is kept constant for the set time T1 by the time limit setting means 28 and is constant based on the set value of the limit value setting means 27. Instead of the limit value, the drive mechanism 23 intermittently applies a driving force to the movable platen 6 by the drive mechanism 23 during the set time T1 to reduce the thrust of the movable platen 6 based on the limit value. It can also be generated in a pulsed manner. In this case, compared with the case where the static thrust is continuously applied to the movable platen 6, the mold 11
The a and 11b are more smoothly removed from each other.

In the above embodiment, the drive mechanism for opening the movable platen 6 is constituted by the hydraulic cylinder 9 and the hydraulic device 22 for operating the same, but instead of the hydraulic cylinder 9, a screw shaft is used. An electric drive that drives a movable platen 6 by rotating one of the screw shaft and the nut with an electric servomotor or the like and linearly moving the other by using a linear moving mechanism in which a nut is screwed onto the movable plate 6. It may be a mechanism. In this case, the limit value of the mold opening force of the movable platen 6 is
The position of the movable platen 6 may be detected by an encoder provided in the electric servomotor or the like instead of the position detector 25. Can be.

[0029]

As described above, the first aspect of the present invention comprises a fixed platen and a movable platen, and the movable platen is moved toward and away from the fixed platen by a driving mechanism to thereby move the fixed platen. In the mold clamping unit configured to open, close, and clamp the mold attached to the movable plate and the movable plate via fixing means, the thrust applied to the movable plate by the drive mechanism when the mold is opened. Is provided with a control means for limiting the value to a preset limit value or less.

According to the apparatus having the above structure, when the mold is opened, the thrust of the movable plate by the drive mechanism is limited to a limit value or less set in advance by the control means. By setting the strength below the strength of the fixing means to fix to the mold mounting board, if the inside of the mold becomes vacuum due to the shrinkage of the resin, or if the slide part of the mold is damaged or adhered, it will be excessively large. A large mold opening force can be prevented from acting on the mold, so that damage to the components of the machine having the weakest strength can be reliably prevented, and safety can be ensured.

According to the second aspect of the present invention, since the limit value of the thrust of the movable plate is set to be equal to or less than the strength of the fixing means, the fixing means of the mold, which is the weakest part, is damaged. Can be prevented, and occurrence of an accident leading to breakage of a machine or a mold can be more reliably prevented.

According to the third aspect of the present invention, since the thrust of the movable platen is continuously limited for a preset time limit after the opening of the movable platen, the guide pins of the mold are fixed. Time to complete the operation of exiting the pin hole, or time to complete the operation of the mold slide core, etc.
The thrust of the movable platen is limited, and the above operation can be safely completed to smoothly perform the mold opening operation.

According to the present invention, when the movable platen does not open to the preset position within the time limit, the movable platen opening operation is stopped, so that the movable platen opening operation is stopped. The movement of the movable platen is stopped immediately in response to the abnormality, and the safety of the machine can be ensured.

According to the fifth aspect of the present invention, when the movable platen does not open the mold to the preset position within the time limit, the alarm generating means for notifying the abnormality of the mold opening is operated. Abnormalities in the mold opening of the movable platen can be reliably detected, and required measures can be taken promptly.

According to the sixth aspect of the present invention, when the movable platen is opened to a preset position within the time limit, the movable platen is moved by a normal thrust when the mold opening amount exceeds the position. Since the opening operation is performed, the mold opening operation of the movable platen can be quickly and reliably performed over the entire section of the mold opening process.

According to the seventh aspect of the present invention, the controller operates the drive mechanism based on the limit value set by the limit value setting means to move the mold of the movable platen,
When the time measured by the time measuring means reaches the time set by the time limit setting means, it is determined whether or not the mold opening movement amount of the movable plate detected by the position detector has reached the reference stroke value by the stroke setting means, Based on the result of the determination, stop the mold opening operation of the movable platen, activate the alarm generation means,
Since the return to the mold opening operation by the normal thrust is performed selectively, the operation from the operation at the time of mold opening of the movable plate to the completion of mold opening based on the set value set by each setting means. Can be performed safely and accurately.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a mold opening safety device for an injection molding machine according to the present invention.

FIG. 2 is an enlarged side view showing a part of a first example of a means for fixing a mold to a mold mounting board in a cross section.

FIG. 3 is a front view showing a first example of means for fixing a mold to a mold mounting board.

FIG. 4 is a sectional view showing a second example of a means for fixing a mold to a mold mounting board.

FIG. 5 is a sectional view showing a third example of means for fixing a mold to a mold mounting board.

FIG. 6 is a flowchart of a mold opening operation of the movable platen.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Mold clamping unit 2 Fixed board (die mounting board) 5 End plate 6 Movable board (die mounting board) 7 Toggle mechanism 9 Hydraulic cylinder 11a, 11b Mold 12 Fixing bolt 14 Holding fixture 16 Clamp lever 22 Hydraulic device 23 Hydraulic pressure Type drive mechanism (drive mechanism) 24 control means 25 position detector 26 controller 27 limit value setting means 28 time limit setting means 29 stroke setting means 30 alarm generation means

Claims (7)

[Claims] 1. A mold comprising a fixed plate and a movable plate, wherein the movable plate is moved toward and away from the fixed plate by a drive mechanism, and is attached to the fixed plate and the movable plate via fixing means. A mold clamping device configured to perform mold opening, mold closing and mold clamping, wherein a control means for restricting a thrust acting on the movable plate by the driving mechanism when the mold is opened to a value equal to or less than a preset limit value. A mold opening safety device for an injection molding machine, which is provided. 2. The safety device according to claim 1, wherein the limit value is set to be equal to or less than the strength of the fixing means. 3. The control device according to claim 1, wherein the control means limits the thrust of the movable platen for a preset time limit after the opening of the movable platen starts. 3. A mold opening safety device for an injection molding machine according to claim 1. 4. The control means is configured to stop the mold opening operation of the movable platen when the movable platen does not open the mold to a preset position within the time limit. The mold opening safety device for an injection molding machine according to claim 3. 5. The method according to claim 1, wherein the control unit is configured to operate an alarm generating unit that notifies an abnormality of the mold opening when the movable platen does not open the mold to a preset position within the time limit. A mold opening safety device for an injection molding machine according to claim 3 or 4, wherein: 6. The control means, when the movable platen is opened to a preset position within the time limit, the movable platen performs a mold opening operation by a normal thrust when the mold opening amount is greater than the position. The mold opening safety device for an injection molding machine according to claim 3, wherein the device is configured to perform the operation. 7. The control means includes: a time measuring means for measuring an elapsed time from the start of opening of the movable plate; a position detector for detecting a moving position of the movable plate after the start of opening of the movable plate; Limit value setting means for setting the limit value of the thrust at the time of mold opening, time limit setting means for setting the time to hold the limit value of the thrust at the time of mold opening of the movable platen, and reference stroke of the mold opening movement of the movable platen Stroke setting means for setting a value, an alarm generating means, and operating the drive mechanism based on the limit value set by the limit value setting means to move the movable platen open, and the time measured by the timing means When the time set by the time limit setting means has been reached, it is determined whether or not the mold opening movement amount of the movable plate detected by the position detector has reached a reference stroke value by the stroke setting means. Also A controller that selectively stops the mold opening operation of the movable platen by the drive mechanism, activates the alarm generation means, and returns to the mold opening operation by normal thrust. Claim 1
The safety device for opening a mold of an injection molding machine according to any one of claims 1 to 6.