JP3258151B2 - Control device for gate cutting pin position of injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the position of a pin for cutting a gate of an injection molding machine, and more particularly, to a resin having a tip end surface in contact with a resin in a product forming space (hereinafter referred to as a cavity) near a gate. Control of the position of the gate cutting pin in the injection molding machine in which the gate cutting pin is advanced before the injection-filled resin is completely solidified to perform gate cutting.
Related to the device .

[0002]

2. Description of the Related Art If a gate cutting pin is advanced and a gate is cut before a resin injected and filled in a cavity is completely solidified, the gate is cut easily while the resin is soft. . No post-processing of gate marks after cutting is required. There is an advantage.

In an injection molding machine employing such a gate cutting technique, the tip surface of the gate cutting pin is at a retracted position at least immediately before injection filling of the molten resin into the cavity, and the injection filling into the cavity is performed. When the gate cutting pin is in the retracted position, when the gate cutting pin is in the retracted position, the capacity of the cavity is reduced. It will be reduced by the forward stroke. That is, the capacity of the cavity is different between the time immediately after the injection and filling of the molten resin and the time after the gate is cut, and the gate cutting pin that is driven forward at the set predetermined driving pressure is moved forward. The shape of the cavity determined when the position is reached needs to match the expected product shape.

Therefore, the retracted position of the gate cutting pin before the injection filling is an important factor for determining the amount of resin to be filled in the cavity, and the gate cutting pin is driven forward from the retracted position at a preset pressure value. The forward limit position of the gate cutting pin, which is determined by balancing the forward force of the gate cutting pin with the reaction force from the resin in the cavity receiving the compressive force, is an important factor that determines the appearance accuracy of the product (molded product). It is a factor. Then, the setting of the retreat position of the gate cutting pin is not appropriate. For example, if the retreat setting position is too late, the amount of the filled resin becomes too large, and the forward limit position of the gate cutting pin becomes closer to the proper position, which is unnecessary When the retreat setting position is too far ahead, the filling resin amount is insufficient, and the forward limit position of the gate cutting pin has passed the appropriate position, and the gate cutting that has protruded too much A product having a recess due to the pin is formed.

As is apparent from the above, the retreat position of the gate cutting pin cannot be achieved unless the retreat position of the gate cutting pin is properly set. While changing the retract position of the pin, a test shot was performed each time to check the appearance of the product (molded product), and finally the retract position of the gate cutting pin was determined to be an appropriate value.

[0006]

Generally, a hydraulic cylinder is used as a driving source of a conventional gate cutting pin. A gate cutting / driving device driven by the hydraulic cylinder and having a gate cutting pin implanted therein is used. By setting the retraction position of the compression plate at the position of a stopper attached to the mold mechanism, the retraction position of the gate cutting pin is set. However, with the configuration in which the retraction setting position of the gate cutting pin is adjusted by adjusting the position of the mechanical stopper, as described above, repeating the test shot while changing the retraction setting position of the gate cutting pin, The operation is extremely complicated and time-consuming, and there is a problem that the workability of adjusting the retreat position of the gate cutting pin is poor.

[0007] Therefore, a technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to perform gate cutting before the resin is completely solidified. An object of the present invention is to realize a control device for a gate cutting pin position of an injection molding machine, in which a retreat position of a gate cutting pin is easily and reliably adjusted in a molding machine.

[0008]

According to the present invention, in order to achieve the above-mentioned object, a molten resin is injected and filled into a product forming space of a clamped mold, and a tip end surface of the mold is formed near a gate. Controlling the gate cutting pin position of the injection molding machine that advances the gate cutting pin that contacts the resin in the space before the resin in the space for product formation is completely solidified and cuts the gate
In the device , a servomotor is used as a drive source for moving the gate cutting pin back and forth, and the set position of the tip surface of the gate cutting pin before injection filling of the molten resin into the mold in the mold-clamped state is stopped by the rotation of the servomotor. Hand adjusting by position
Steps are provided.

[0009]

When setting the retraction position of the gate cutting pin, first, the operator temporarily sets the retraction position of the gate cutting pin, causes the machine (injection molding machine) to execute the first trial shot, and obtains the trial shot. Products (molded products)
Is visually inspected to determine the amount of resin charged into the cavity. When the filling resin amount is too large, the gate cutting pin retreat setting position moves forward by a predetermined amount from the retreat setting position of the gate cutting pin in the first test shot in a forward direction (a direction in which the filling resin amount decreases). If the amount of the filling resin is too small, the gate cutting pin is retracted by a predetermined amount in the backward direction (in the direction in which the amount of the filling resin increases) from the retreat set position of the gate cutting pin in the first trial shot. An instruction to move the set position backward is given to, for example, a microcomputer (microcomputer) that controls the machine by a key input device. With this, the microcomputer updates the setting data of the retreat position of the gate cutting pin in the next shot and controls the servomotor based on this to set the retreat setting position, which is the standby position of the gate cutting pin before injection filling. , In the designated direction by the designated amount. In this state, perform the next test shot, similarly visually inspect the appearance of the product, judge the amount of the filled resin, and give an instruction to correct the retreat setting position of the gate cutting pin in the direction that good product molding is achieved. Go to the next test shot. In this way, the test shot is repeated while correcting the retracted set position of the gate cutting pin, and the retracted set position of the gate cutting pin is adjusted until a product having a complete appearance without sink marks or the like is obtained. At the time when a product with perfect appearance without sink marks etc. is obtained, the microcomputer is instructed to determine the retracted setting position of the gate cutting pin at that time as setting data for continuous automatic molding operation, and This completes the adjustment of the retracted position of the gate cutting pin.

In this way, the retreat setting position, which is the standby position of the gate cutting pin before injection filling, is adjusted by the rotation stop position of the servomotor by, for example, a change command from the key input device, so that the burden on the operator is reduced. The adjustment of the retreat position of the gate cutting pin is facilitated, and the adjustment time is shortened.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory diagram showing a mechanism around a mold and a main part control system in the injection molding machine according to the present embodiment. In the figure, 1 is a fixed die plate, 2 is a fixed side die attached to the fixed die plate 1,
Although not shown, a nozzle of a well-known in-line screw type injection mechanism is pressed against the resin injection portion 2b of the sprue forming member 2a in the fixed mold 2. Reference numeral 3 denotes a movable die plate, which is moved forward and backward with respect to the fixed die plate 1 by an appropriate mold opening / closing drive source (eg, a mold-clamping hydraulic cylinder or a mold-clamping motor) and a mold opening / closing mechanism (eg, a toggle link mechanism). It is possible. 4
Is a movable mold attached to the movable die plate 3 via the mold supporting member 5, and in the clamped state shown in FIG. 1, the PL surface (separation) between the movable mold 3 and the fixed mold 2 is set. The two molds 2 and 3 form a cavity 6 as a space for forming a molded product. In the present embodiment, the cavity 6 communicates with the resin injection portion 2b of the fixed mold 2 via a submarine-type gate 7, a runner equivalent portion 8, and a sprue 9.

Reference numeral 10 denotes an eject drive shaft mounted on the movable die plate 3 so as to be able to move forward and backward. An eject drive source (not shown) suitably mounted on the movable die plate 3 (for example, Hydraulic cylinder, etc.). An eject plate 11 is connected to the eject drive shaft 10 and has a plurality of eject pins 12 implanted therein. In the mold clamping state shown in FIG. 1, the tip end surface of the eject pin 12 is located at the retreat limit position, and after the mold opening is completed or during the mold opening, the eject pin 12 is driven forward by an eject drive source (not shown). Then, a product (molded product corresponding to the cavity 6) and an unnecessary resin portion (portion corresponding to the runner equivalent portion 8 and the sprue 9) adhered to the movable mold 3 are projected. The retreat limit position of the eject plate 11 (the eject pin 12) is regulated by a stopper (not shown).

Reference numeral 13 denotes a gate cut / compression drive shaft mounted on the movable die plate 3 so as to be able to move back and forth, and a gate cut / compression servomotor 14 also mounted on the movable die plate 3. And a rotary-linear motion converting mechanism (for example, a mechanism for converting a rotary motion using a known ball screw into a linear motion) 15 also provided on the movable die plate 3, and is connected to a gate cut / compression. The drive shaft 13 is driven back and forth by a servomotor 14. 16
Is a gate cut / compression plate which is held so as to be able to move forward and backward with respect to the movable mold 5; a plurality of gate cut / compression pins 17 (gate cutting pins in claims) and guide pins The gate cut / compression pin 17 and the guide pin 18 can move forward and backward in the movable mold 5. 19 is the guide pin 1
A compression spring loosely inserted in 8 has both ends elastically in contact with the movable mold 5 and the gate cut / compression plate 16, whereby the gate cut / compression plate 16 is attached in the retreating direction (leftward direction in the figure). The gate cut / compression plate 16 is constantly pressed against the tip of the gate cut / compression drive shaft 13. Further, the tip end surface of the gate cut / compression pin 17 forms a part of the inner wall of the cavity 6 near the gate 7, and as described later,
Before the resin in the cavity 6 is completely solidified, it is driven forward to cut the gate.

Reference numeral 20 denotes a microcomputer (microcomputer) serving as a system controller for controlling the entire machine (injection molding machine). The microcomputer 20 controls the operation of each part of the machine based on various operation control programs and various setting data created in advance. I do. Reference numeral 21 denotes a motor driver for controlling the driving of the servo motor 14. The microcomputer 20 gives a command to the motor driver 21 based on the control condition data of the gate cut / compression pin 17 stored in the set condition value storage unit 20a built therein. As a result, the servo motor 14 rotates in an appropriate direction or stops at a specified position. Reference numeral 22 denotes a rotation position detection sensor that detects the rotation position of the servo motor 14. Based on detection information from the rotation position detection sensor 22, the microcomputer 20
The position of the gate cut / compression pin 17 corresponding to the rotational position of (1) is recognized. Reference numeral 23 denotes an input operation unit composed of a key input device or the like. By operating the input operation unit 22, the control condition data (setting data) given to the microcomputer 20 is changed, and the operation start / stop is instructed. It has become.

In the above-described structure, when the molten resin is injected and filled into the clamped mold by an injection mechanism (not shown), the molten resin is injected at an appropriate timing after the injection filling (an appropriate timing before the resin is completely solidified). ), The servo motor 14 is driven to rotate in a predetermined direction by a command from the microcomputer 20. As a result, the gate cut / compression pin 17 is driven forward from the retreat set position via the rotation-linear motion conversion mechanism 15, the gate cut / compression drive shaft 13, and the gate cut / compression plate 16. When the gate cut / compression pin 17 moves forward, the servo motor 14 is driven with a drive current value corresponding to a predetermined holding pressure value (which is previously written in the set condition value storage unit 20a). When driven, the gate cut / compression pin 17 moves forward with a predetermined forward force value. When the gate cut / compression pin 17 advances, the fragile resin at the gate 7 is cut, and the resin in the cavity 6 receives a pressing force (compression stress) by the subsequent advance of the gate cut / compression pin 17. When the pressing force (holding force) of the gate cut / compression pin 17 based on the set torque of the servomotor 14 and the reaction force from the resin in the cavity 6 are balanced, the gate cut / compression pin 17 reaches the forward limit position.

In this embodiment, the gate cut / compression pin 1
When the microcomputer 7 detects that the forward end position has been reached, the microcomputer 2
In FIG. 2, the servo motor 14 is slightly rotated in the normal and reverse directions to cause the gate cut / compression pin 17 to vibrate as shown in FIG. It is designed to apply pressure. After that, when the resin is solidified, the mold opening operation and the ejecting operation are performed as shown in FIG.
As described above, the product adhered to the movable mold 3 and the unnecessary resin portion are protruded by the eject pin 12 in a state of being separated.

In the above description of the operation, if the retreat setting position, which is the standby position of the gate cut / compression pin 17 after the completion of the mold clamping and before the injection filling, is an appropriate value,
The resulting product is a good product having a perfect appearance without sink marks. However, the gate cut / compression pin 17
If the retreat setting position is too far behind, the amount of the filled resin becomes too large, and as shown in FIG. 4, the forward limit position of the gate cut / compression pin 17 is closer to an appropriate position, and a product having an unnecessary protrusion is formed. Will be formed. Conversely, if the retreat setting position of the gate cut / compression pin 17 is too far ahead, the amount of the filled resin is insufficient, and as shown in FIG. 5, the forward limit position of the gate cut / compression pin 17 passes through the proper position. Thus, a product having a dent due to the gate cut / compression pin 17 that is excessively protruded is formed. At the time of the initial operation after the mold exchange (at the time of the initial shot), it is substantially difficult to determine the retreat setting position of the gate cut / compression pin 17 to an appropriate value. In general, there is a tendency shown in FIG.
It is necessary to adjust the retreat setting position.

Next, the adjustment of the retracted position of the gate cut / compression pin 17 will be described. In adjusting the retreat position of the gate cut / compression pin 17, first, the operator inputs the provisional retreat setting position data of the gate cut / compression pin 17 to the microcomputer 20 by the input operation means 23, and then inputs the data to the microcomputer 20 for the first time. Instruct the execution of the test shot. As a result, the microcomputer 20 keeps the gate cut / compression pin 17 at the retreat position according to the temporary retreat setting position data (that is, the servo motor 14 is held at the predetermined rotation stop position), The machine (injection molding machine) executes the first trial shot. Then, the operator visually inspects the appearance of the product (molded product) obtained by the test shot, and determines the amount of the resin filled in the cavity 6.

If the amount of the filled resin in the first trial shot is too large, the gate cut / compression pin 17 in the first trial shot is moved forward from the set position (the direction in which the amount of the filled resin decreases). In addition, gate cut / predetermined amount
An instruction such that the retraction set position of the compression pin 17 is advanced,
The operator inputs to the microcomputer 20 by the input operation means 23. When the amount of the filled resin in the first trial shot is small, the predetermined amount is set in the backward direction (the direction in which the amount of the filled resin increases) from the set position of the gate cut / compression pin 17 in the first trial shot. An instruction is input to the microcomputer 20 such that the retreat setting position of the gate cut / compression pin 17 only retreats. Here, in the present embodiment, the set unit (minimum adjustment amount) of the retreat setting position of the gate cut / compression pin 17 is 0.01 mm, but this value is arbitrary.

As a result, the microcomputer 20 updates the set data of the retreat position of the gate cut / compression pin 17 in the next shot, and controls the servo motor 14 based on the updated data to control the gate cut / compression before injection filling. The retracted setting position, which is the standby position of the compression pin 17, is varied by the specified amount in the specified direction. Similarly, the next test shot is similarly performed, and the appearance of the product is similarly visually inspected to determine whether the amount of the filled resin is large. An instruction to further correct the direction is issued, and the next test shot is executed.

In this way, the test shot is repeated while correcting the set position of the gate cut / compression pin 17 to retreat, and the gate cut / compression pin 17 is set to the retreat position until a product having a complete appearance without sink marks or the like is obtained. Adjust the position.
Then, when a product having a complete appearance without sink marks or the like is obtained, the operator can operate the gate cut / compression pin 1 at that time.
7 is instructed to the microcomputer 20 to determine the retreat setting position as the setting data for the continuous automatic molding operation, whereby the adjustment operation of the retreat position of the gate cut / compression pin 17 is completed.

In this way, the reversing set position, which is the standby position of the gate cut / compression pin 17 before injection filling, is adjusted by the rotation stop position of the servo motor 14 by a change command from the key input device, for example, so that the operator is required. The burden is reduced, the retraction position of the gate cut / compression pin 17 is easily adjusted, and the adjustment time is also shortened.

[0023]

As described above, according to the present invention, it is easy to adjust the retreat position of the gate cutting pin (gate cut / compression pin) in the injection molding machine that cuts the gate before the resin is completely solidified. A reliable control method of the position of the gate cutting pin of the injection molding machine can be realized, and its industrial value is great.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a mechanism around a mold and a main part control system in an injection molding machine according to one embodiment of the present invention.

FIG. 2 is an explanatory view of a mechanism around a mold showing a state after a gate cutting pin (gate cut / compression pin) advances and performs gate cutting in the injection molding machine of FIG. 1;

FIG. 3 is an explanatory view of a mechanism around a mold showing a state where a mold opening and an ejecting operation are performed in the injection molding machine of FIG. 1;

FIG. 4 is an explanatory view of a mechanism around a mold showing a state after the gate cutting pin has advanced when the retreat setting position of the gate cutting pin is not proper in the injection molding machine of FIG. 1;

FIG. 5 is an explanatory view of a mechanism around a mold showing a state after the gate cutting pin has advanced in a case where the retreat setting position of the gate cutting pin is not proper in the injection molding machine of FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 fixed die plate 2 fixed die 3 movable die plate 5 movable die 6 cavity (space for product molding) 7 gate 12 eject pin 13 gate cut / compression drive shaft 14 gate cut / compression servo motor 15 rotation- Linear motion conversion mechanism 16 Gate cut / compression plate 17 Gate cut / compression pin (gate cutting pin) 18 Guide pin 19 Compression spring 20 Microcomputer (microcomputer) 21 Motor driver 22 Rotational position detection sensor 23 Input operation means

Claims (2)

(57) [Claims] 1. A gate cutting pin in which a molten resin is injected and filled into a product forming space of a clamped mold, and a tip surface of which is in contact with the resin in the product forming space near a gate,
In an injection molding machine for cutting a gate by advancing the resin in the product forming space before it is completely solidified, a servomotor is used as a drive source for moving the gate cutting pin back and forth, and a mold is clamped in a mold. The set position of the tip surface of the gate cutting pin before injection filling with molten resin,
Means for adjusting by the rotation stop position of the servo motor
Controller of the gate cutting pin position of the injection molding machine and having a. 2. The gate cutting pin according to claim 1, wherein the gate cutting pin functions to apply a compressive stress to the resin in the product forming space after the gate cutting, and the gate cutting pin has a predetermined setting. A driving force of the servomotor controlled by a driving current value corresponding to a pressure value,
A gate cutting pin position control apparatus for an injection molding machine, wherein the apparatus is driven forward to a forward limit position determined by a reaction force from a resin in the product forming space.