JP2003025398A - Mold clamping apparatus and method for injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a damage of a mold surface due to a foreign matter by eliminating stopping of a movable platen caused by an excessively low movable mold compressing force and stopping the platen by a resistance of the foreign matter even when the matter adhered to the mold surface of the movable mold or a fixed mold is relatively small. SOLUTION: An apparatus for clamping the mold of an injection molding machine comprises a mold unit having the fixed mold and the movable mold, a movable mold support member for supporting the movable mold, a crosshead, a toggle mechanism having a base end mounted at a toggle mechanism support member, and a distal end mounted at the movable mold support member, a drive source for moving the crosshead, and a controller for gradually lowering the mold clamping force of the drive source if a position of the movable mold support member advanced into a section for raising a toggle magnification of the toggle mechanism, when the movable member support member is advanced to clamp the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device and method for an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, resin melted and heated in a heating cylinder is injected at a high pressure to fill the cavity space of a mold device.
A molded product is molded by cooling and solidifying the resin in the cavity space.

To this end, the mold device is composed of a fixed mold and a movable mold, and the mold clamping device moves the movable mold forward and backward to bring the movable mold into and out of contact with the fixed mold to open and close the mold. , Mold closing, mold clamping and mold opening can be performed. And the mold clamping device is
In general, a fixed platen that holds a fixed mold and a movable platen that holds a movable mold are provided, and a toggle mechanism as an opening / closing device that advances and retracts the movable platen is provided, and the toggle mechanism is provided in a drive unit. It is operated by driving a drive source such as a hydraulic cylinder or an electric motor.

Generally, as the toggle mechanism, an inner winding 5-bar double toggle mechanism is often used because the entire length of the mold clamping device can be shortened. In this case, when the drive source attached to the back surface of the toggle support that supports the base end of the toggle mechanism is operated, the crosshead advances and retracts to expand and contract the toggle link, which is attached to the tip of the toggle mechanism. The movable platen can be moved back and forth along the guide member.

Here, as a feature of the operation of the toggle mechanism, when the movable platen is located rearward and the movable mold is separated from the fixed mold, the movable platen moves with respect to the moving amount of the crosshead. It is in an accelerating state in which the moving amount is larger. Then, when the movable platen advances and the distance between the movable mold and the fixed mold becomes a predetermined value or less, the relationship between the movement amount of the crosshead and the movement amount of the movable platen is reversed,
The deceleration state is such that the movement amount of the crosshead is larger than the movement amount of the movable platen. The ratio of the amount of movement of the cross head to the amount of movement of the movable platen is called the toggle magnification. When the toggle magnification is 1 or less, the speed is in the acceleration state, and when the toggle magnification is 1 or more, the speed is in the deceleration state. .

In the general toggle mechanism, the relationship between the position of the movable platen and the toggle magnification is constant in most of its moving section after the movable platen is moved forward from the mold open position. The value of the toggle magnification is 1 or less. Therefore, in this section, the moving amount of the movable platen is larger than the moving amount of the crosshead, which is an accelerating state.

Next, when the position of the movable platen approaches the mold closing position, the toggle magnification rapidly increases to 1 or more. That is, the relationship between the movement amount of the cross head and the movement amount of the movable platen is reversed, and the movement amount of the cross head is larger than the movement amount of the movable platen, resulting in a deceleration state. The toggle magnification rapidly increases in the section where the position of the movable platen is from the guide pin insertion position to the mold contact position. Here, the guide pin insertion position is a position where the guide pin attached to the movable mold starts to enter the guide pin insertion hole formed in the fixed mold, and the mold contact position is movable. This is the position where the die surface of the die starts contacting the die surface of the fixed die.

Therefore, when a constant force is applied to the crosshead to move the crosshead at a constant speed, the toggle magnification rapidly increases when the movable platen reaches the vicinity of the mold contact position, so that the movable mold moves. Although the speed decreases, the mold clamping force of the movable mold increases rapidly.

Here, when foreign matter adheres to the mold surface of the movable mold or the fixed mold and the mold clamping force of the movable mold is low,
Since the movable platen stops due to the resistance of the foreign matter sandwiched between the mold surface of the movable mold and the mold surface of the fixed mold, the mold is not closed. However, when the mold clamping force of the movable mold is high, the movable platen continues to move forward by overcoming the resistance of the foreign matter, and the mold is closed. It will be damaged by the foreign matter.

Therefore, in the conventional mold clamping device of the injection molding machine, when the movable platen reaches the vicinity of the mold contact position, the mold clamping force is controlled so as to reduce the force applied to the crosshead.

FIG. 2 is a diagram showing a conventional mold clamping method for an injection molding machine.

In the figure, the curve G in the graph (a)
Represents the relationship between the movable mold clamping force and the movable platen position,
Curve H in graph (b) represents the relationship between the driving source mold clamping force applied to the crosshead and the movable platen position. On the horizontal axis, o is the mold opening position where the movable platen is located at the rearmost position, g is the low-pressure mold clamping start point for decreasing the mold clamping force, h is the high-pressure mold clamping starting point for increasing the mold clamping force, and i is This is the mold closed position in which the movable platen is located at the frontmost position. At the mold closing position i, the mold is closed.

Further, j on the vertical axis of the graph (a) is
It is the minimum movable mold clamping force as the movable mold clamping force required to move the movable platen by overcoming the frictional resistance of the guide pin or the like.

First, as shown by the curve H, the driving source mold clamping force is constant in the section from the mold opening position o to the low pressure mold clamping start point g when the movable platen moves. . Since the toggle magnification is substantially constant in the section, the movable mold clamping force is constant as represented by the curve G. The low-pressure mold clamping start point g is a position substantially corresponding to the guide pin insertion position.

Next, when the movable platen position reaches the low pressure mold clamping start point g, the drive source mold clamping force is reduced as shown by the curve H. As a result, the movable mold clamping force temporarily decreases at the low-pressure mold clamping starting point g that substantially corresponds to the guide pin insertion position. Here, since the value of the movable mold clamping force reduced at the low-pressure mold clamping start point g is equal to or more than the minimum movable mold clamping force j, the movable platen stops due to the friction resistance of the guide pin or the like. There is nothing to do.

Subsequently, as shown by the curve G, the movable mold clamping force sharply increases after the low-pressure mold clamping start point g, because the toggle ratio sharply increases. And
When the movable platen approaches the high-pressure mold clamping start point h, the movable mold clamping force becomes a considerably high value. The high-pressure mold clamping start point h is a position substantially corresponding to the mold contact position.

Next, when the movable platen position reaches the high pressure mold clamping start point h, the drive source mold clamping force is increased as shown by the curve H until the low pressure mold clamping start point g is reached. The value must be greater than or equal to Therefore, since the movable mold clamping force has a high value after the high-pressure mold clamping start point h substantially corresponding to the mold contact position, the mold is effectively clamped, heated, and melted. Even if the resin is injected at a high pressure and fills the cavity space of the mold device, the resin does not leak.

As described above, when the movable platen position reaches the low pressure mold clamping start point g, the driving source mold clamping force is reduced and the movable mold clamping force is reduced, so that the mold of the movable mold or the fixed mold is reduced. When foreign matter is attached to the mold surface, the movable platen stops due to the resistance of the foreign matter sandwiched between the mold surface of the movable mold and the mold surface of the fixed mold. Therefore, since the mold is not closed, the mold surface of the movable mold or the fixed mold is not damaged by the foreign matter.

[0019]

However, in the mold clamping device and method for the conventional injection molding machine described above, when the foreign matter adhered to the mold surface of the movable mold or the fixed mold is relatively small, The movable mold may have a high mold clamping force, overcome the resistance of the foreign matter, and the movable platen may continue to move forward to close the mold. As a result, the mold surface of the movable mold or the fixed mold is damaged by the foreign matter.

As shown by the curve G in FIG. 2, the movable mold clamping force temporarily decreases at the low pressure mold clamping start point g at which the movable platen position substantially corresponds to the guide pin insertion position, but rises rapidly. Then, when the movable platen position approaches the high-pressure mold clamping start point h substantially corresponding to the mold contact position, the value becomes considerably high. And, a small foreign matter is sandwiched between the mold surface of the movable mold and the mold surface of the fixed mold and becomes a resistance,
This is after the movable platen position approaches the high pressure mold clamping start point h. Therefore, when the foreign matter is small, the movable platen position approaches the high-pressure mold clamping start point h, and the movable mold clamping force is increased to be more than the resistance of the foreign matter. Therefore, since the movable platen continues to move forward and the mold is closed, the mold surface of the movable mold or the fixed mold is damaged by the foreign matter.

Even if the foreign matter is small, in order to stop the movable platen by the resistance of the foreign matter sandwiched between the mold surface of the movable mold and the mold surface of the fixed mold, the movable platen in FIG. As shown by the curve H ′, it is possible to reduce the driving source mold clamping force. In this case, the movable mold clamping force is
As represented by the curve G ′, the movable platen position is maintained at a low value even when the movable platen position approaches the high pressure mold clamping start point h. However, when the movable platen position is at the low-pressure mold clamping start point g, the movable mold clamping force becomes equal to or less than the minimum movable mold clamping force j, so that the movable platen stops due to the frictional resistance of the guide pin or the like.

The present invention solves the problems of the conventional mold clamping apparatus and method for an injection molding machine, and the movable mold clamping force does not become too low to stop the movable platen. Moreover, even if the foreign matter adhered to the mold surface of the movable mold or the fixed mold is relatively small, the movable platen stops due to the resistance of the foreign matter, preventing the mold surface from being damaged by the foreign matter. An object of the present invention is to provide a mold clamping device and method for an injection molding machine that can perform the above.

[0023]

Therefore, in a mold clamping device of an injection molding machine of the present invention, a mold device having a fixed mold and a movable mold, and a movable mold support for supporting the movable mold. A toggle mechanism having a member and a crosshead, the base end of which is attached to the toggle mechanism support member and the tip of which is attached to the movable mold support member, a drive source for moving the crosshead, and the movable mold. When the support member is moved forward to perform mold clamping, if the position of the movable mold support member enters a section where the toggle magnification of the toggle mechanism increases,
And a controller for gradually reducing the mold clamping force of the drive source.

In the mold clamping device of another injection molding machine of the present invention, the control device further reduces the mold clamping force of the drive source in a plurality of stages.

In the mold clamping device of still another injection molding machine of the present invention, the control device further reduces the mold clamping force of the drive source in proportion to the moving distance of the movable mold supporting member.

In the mold clamping device of still another injection molding machine of the present invention, the control device further reduces the mold clamping force of the drive source to the reciprocal of the toggle magnification.

In still another mold-clamping device for an injection molding machine of the present invention, the control device further comprises a mold for the drive source so that the mold-clamping force of the movable mold becomes equal to or higher than the minimum movable mold-clamping force. Reduce the tightening force.

In the mold clamping method for the injection molding machine of the present invention, the drive source is operated to move the crosshead forward to operate the toggle mechanism, and the movable mold for supporting the movable mold attached to the tip of the toggle mechanism is operated. When the mold support member is advanced and the position of the movable mold support member enters a section where the toggle magnification of the toggle mechanism increases, the mold clamping force of the drive source is gradually reduced.

In the mold clamping method for another injection molding machine of the present invention, the mold clamping force of the drive source is further reduced in a plurality of steps.

In the mold clamping method of still another injection molding machine of the present invention, the mold clamping force of the drive source is further reduced in proportion to the moving distance of the movable mold supporting member.

In the mold clamping method of still another injection molding machine of the present invention, the mold clamping force of the drive source is further reduced to the reciprocal of the toggle magnification.

In the mold clamping method of still another injection molding machine of the present invention, the mold clamping force of the drive source is further reduced so that the mold clamping force of the movable mold becomes equal to or more than the minimum movable mold clamping force. Let

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a schematic view showing the state of the mold clamping device of the injection molding machine in the first embodiment of the present invention when the mold is closed, and FIG. 4 is the injection molding machine in the first embodiment of the present invention. FIG. 6 is a schematic view showing a state of the mold clamping device when the mold is opened.

In the figure, 11 is a frame of the injection molding machine 10, 12 is a fixed platen fixed to the frame 11, 13 is a predetermined distance from the fixed platen 12, and the frame 11 is fixed to the frame 11. The toggle support is a toggle mechanism support member that is movably arranged.

Reference numeral 14 denotes a movable platen as a movable mold supporting member which is disposed so as to face the fixed platen 12 and is movable along a tie bar (not shown) so as to be movable back and forth (movable in the left-right direction in the drawing). is there. Further, a fixed mold 16 is attached to a fixed mold mounting surface 15 of the fixed platen 12 facing the movable platen 14, and the fixed platen 1 of the movable platen 14 is attached.
The movable die 18 is attached to the movable die mounting surface 17 that faces the movable die 18.

Here, the movable mold surface 25 of the movable mold 18
A single or a plurality of guide pins 27 are attached to the fixed mold surface of the fixed mold 16 and the guide pins 27 are attached to the fixed mold surface 26 of the fixed mold 16.
The guide pin insertion holes 28 respectively corresponding to the above are formed. Then, when the mold is closed as shown in FIG. 3, the guide pins 27 are inserted into the corresponding guide pin insertion holes 28. As a result, the movable mold surface 25 of the movable mold 18 and the fixed mold surface 26 of the fixed mold 16 are accurately aligned, and the movable mold surface 25 and the fixed mold surface 26 are aligned with each other. Since the accuracy of the shape of the cavity space (not shown) formed is improved, the quality of the molded product formed by cooling and solidifying the resin filled in the cavity space is improved.

The guide pin 27 is used for the movable mold 1.
Instead of the movable mold surface 25 of No. 8, it may be attached to the fixed mold surface 26 of the fixed mold 16. In this case, the guide pin insertion hole 28 is formed not on the fixed mold surface 26 of the fixed mold 16 but on the movable mold surface 25 of the movable mold 18.

A drive device (not shown) for moving an ejector pin may be attached to the rear end (left end in the figure) of the movable platen 14.

A toggle mechanism 20 as a toggle type mold clamping device is provided between the movable platen 14 and the toggle support 13, and a mold clamping drive for operating the toggle mechanism 20 at the rear end of the toggle support 13. A mold clamping cylinder device 31 as a source is attached. The mold clamping cylinder device 3
1 has a piston 32 that is moved by hydraulic pressure and a piston rod 33 that has one end attached to the piston 32 and the other end attached to the crosshead 21 as a driven member.

Here, the toggle mechanism 20 is an inner winding 5-bar double toggle mechanism and swings with respect to the toggle lever 22 and the toggle support 13 which are swingably supported by the crosshead 21. A toggle lever 23 supported freely, and a toggle arm 24 swingably supported with respect to the movable platen 14, between the toggle lever 22 and the toggle lever 23, and between the toggle lever 23 and the toggle lever 23. The arms 24 are linked to each other.

As a result, the mold clamping cylinder device 31 is actuated, and the piston 32 and the piston rod 33 are moved as shown in FIG.
When the movable platen 14 is moved forward (moved to the right in the drawing) from the state shown in FIG. 3, the movable platen 14 is moved forward to close the mold, and the state shown in FIG. And
The mold clamping force is generated by multiplying the propulsive force of the mold clamping cylinder device 31 by the toggle ratio, and the mold clamping force is used to perform the mold clamping.

The mold clamping cylinder device 31 includes a pressure oil supply mechanism such as a hydraulic pump, a pressure oil pipe, an accumulator and the like, and a pressure oil control mechanism for controlling the supply amount and supply pressure of the pressure oil, which are not shown. This makes it possible to control the speed at which the cross head 21 is moved by the piston 32 and the piston rod 33 and the drive source mold clamping force that is the force for moving the cross head 21.

Further, the mold clamping drive source for operating the toggle mechanism 20 does not have to be a device that operates by hydraulic pressure such as the mold clamping cylinder device 31, and for example, an electric motor such as a servo motor is used. It may be a device.
In this case, an electric motor is attached to the toggle support 13 and a ball screw mechanism composed of a ball screw shaft and a ball screw nut is arranged on the rotary shaft of the electric motor to reciprocate the rotary motion of the rotary shaft of the electric motor. The cross head 21 is converted and moved back and forth. The rotation of the electric motor may be transmitted to the rotary shaft attached to the toggle support 13 by a pulley or a belt. When the mold clamping drive source is an electric motor, the speed at which the crosshead 21 is moved and the drive source mold clamping force are electrically controlled.

In the present embodiment, the resin is injected at a high pressure from an injection device (not shown) arranged on the right side of the stationary platen 12 in the drawing, and is filled in the cavity space of the mold device. ing. The injection device has a heating cylinder having a screw inside, and injects the resin heated and melted in the heating cylinder at a high pressure. Then, the molded product is molded by cooling and solidifying the resin in the cavity space.

The injection molding machine 10 also has a control device (not shown). The control device has a computing unit such as a CPU and MPU, a storage unit such as a semiconductor memory and a hard disk, an input unit such as a keyboard and a touch panel, a display unit such as a CRT and a liquid crystal display, and an I / O (input / output interface). Then, the operations of all or a part of the mold clamping device, the injection molding machine 10 and the devices associated with the injection molding machine 10 are comprehensively controlled. The control device does not have to be independent, and may be integrated with another control device. The controller also controls the operation of the pressure oil supply mechanism and the pressure oil control mechanism, the electric motor, and the like.

Next, the operation of the mold clamping device of the injection molding machine having the above construction will be described. First, the operation of the toggle mechanism 20 will be described.

In the case of the inner winding 5-bar double toggle mechanism such as the toggle mechanism 20, as shown in FIG. 4, the movable platen 14 is located rearward, and the movable mold 18 is separated from the fixed mold 16. At the time, the moving amount of the movable platen 14 is larger than the moving amount of the cross head 21, which is an acceleration state. When the movable platen 14 moves forward and the distance between the movable mold 18 and the fixed mold 16 becomes a predetermined value or less,
The relationship between the moving amount of the cross head 21 and the moving amount of the movable platen 14 is reversed, and the moving amount of the cross head 21 is larger than the moving amount of the movable platen 14 in a deceleration state. The state in which the toggle magnification is 1 or less, which is the ratio of the amount of movement of the cross head 21 to the amount of movement of the movable platen 14, is the acceleration state, and the state of 1 or more is the deceleration state.

FIG. 5 is a diagram showing the relationship between the position of the movable platen and the toggle magnification in the toggle mechanism according to the first embodiment of the present invention, and FIG. 6 is the K of FIG. 5 according to the first embodiment of the present invention. FIG.

In FIG. 5, the horizontal axis represents the movable platen position, which is the position of the movable platen 14, and the vertical axis represents the toggle magnification. As shown in FIG. 4, o on the horizontal axis is the mold opening position in which the movable platen 14 is located at the rearmost position, and k is the movable platen 14 as shown in FIG.
Is the mold closing position located at the frontmost position. At the mold closing position k, the mold is closed.

In the toggle mechanism 20, the relationship between the movable platen position and the toggle magnification changes like a curve J.
That is, after the movable platen 14 moves forward from the mold open position o, the toggle magnification is almost constant and is 1 or less in most of the moving section thereof. Therefore, in this section, the moving amount of the movable platen 14 is larger than the moving amount of the cross head 21, which is an acceleration state.

Then, when the movable platen position approaches the mold closing position k, the toggle magnification rapidly increases to 1 or more. That is, the relationship between the movement amount of the cross head 21 and the movement amount of the movable platen 14 is reversed, and the movable platen 14 is reversed.
The amount of movement of the crosshead 21 is larger than the amount of movement of the deceleration state. As shown in FIG. 6, it can be seen that the toggle magnification rapidly increases in the section where the movable platen position is from the guide pin insertion position 1 to the mold contact position m. Here, the guide pin insertion position 1 is a position where the guide pin 27 attached to the movable mold 18 starts to enter the guide pin insertion hole 28 formed in the fixed mold 16, and The contact position m is a position where the movable mold surface 25 of the movable mold 18 starts to contact the fixed mold surface 26 of the fixed mold 16.

Therefore, when a constant force is applied to the crosshead 21 to move it at a constant speed, the movable platen 14
When reaches the vicinity of the mold contact position m, the toggle magnification rapidly increases, so that the moving speed of the movable mold 18 decreases, but the mold clamping force rapidly increases.

FIG. 1 is a diagram showing a mold clamping method for an injection molding machine according to the first embodiment of the present invention.

In the figure, curve A in graph (a)
Reference numeral 1 represents the relationship between the movable mold clamping force and the movable platen position, and line B1 in the graph (b) represents the relationship between the drive source clamping force applied to the crosshead 21 and the movable platen position. On the horizontal axis, o is the mold opening position,
a is a first-stage low-pressure mold clamping start point for decreasing the mold clamping force, b is a second-stage low-pressure mold clamping starting point for further reducing the mold clamping force, c is a high-pressure mold clamping starting point for increasing the mold clamping force, k Is the mold closing position.

Further, e on the vertical axis of the graph (a) is
The movement required to move the movable platen 14 by overcoming the resistance such as the frictional resistance generated between the guide pin 27 and the guide pin insertion hole 28 and the frictional resistance generated between the movable platen 14 and a tie bar (not shown). It is the minimum movable mold clamping force as the mold clamping force.

First, in the section from when the movable platen 14 moves from the mold opening position o to when it reaches the first stage low pressure mold clamping start point a, as shown by the line B1, the driving source mold clamping force is given. Is constant. Since the toggle magnification is almost constant in the section, as shown by the curve A1,
The movable mold clamping force is constant. It is desirable that the first-stage low-pressure mold clamping start point a is a position substantially corresponding to the guide pin insertion position l.

Next, when the movable platen position reaches the first-stage low-pressure mold clamping start point a, the drive source mold clamping force is reduced by one step in a step-like manner as indicated by the line B1. It should be noted that the movable platen position is the first stage low pressure mold clamping start point a.
To the second stage low-pressure mold clamping starting point b,
The drive source mold clamping force is constant. Therefore, the movable mold clamping force is temporarily reduced at the first-stage low-pressure mold clamping starting point a which substantially corresponds to the guide pin insertion position l. Here, since the value of the movable mold clamping force reduced at the first stage low pressure mold clamping starting point a is equal to or more than the minimum movable mold clamping force e, the guide pin 27 and the guide pin insertion hole 28 are separated from each other. Between the frictional resistance generated between the movable platen 14 and the tie bar (not shown),
The movable platen 14 never stops.

Subsequently, when the movable platen position advances beyond the first-stage low-pressure mold clamping start point a, the toggle magnification rapidly increases after the first-stage low-pressure mold clamping start point a. The mold clamping force rises rapidly. But,
When the movable platen position reaches the second-stage low-pressure mold clamping start point b, the drive source mold clamping force is further reduced by one step in a step-like manner as indicated by the line B1. When the movable platen position is in the section from the second stage low pressure mold clamping start point b to the high pressure mold clamping start point c, the drive source mold clamping force is constant. Therefore, the movable mold clamping force is reduced again at the second stage low pressure mold clamping start point b. It can be seen from the curve A1 that the movable mold clamping force immediately before the second-stage low-pressure mold clamping start point b does not exceed the value in the section until reaching the first-stage low-pressure mold clamping start point a.

Here, the value of the movable mold clamping force reduced at the second stage low pressure mold clamping start point b is equal to or more than the minimum movable mold clamping force e. The position of the second-stage low-pressure mold clamping starting point b is an intermediate point between the first-stage low-pressure mold clamping starting point a and the high-pressure mold clamping starting point c, that is, the first-stage low-pressure mold clamping starting point a and It is desirable to be equidistant from the high-pressure mold clamping start point c, but it can be changed appropriately. Further, the high pressure mold clamping start point c is a position substantially corresponding to the mold contact position m.

When the movable platen position approaches the high-pressure mold clamping start point c, the toggle magnification rapidly increases.
Although the value of the movable mold clamping force rises rapidly, it does not become so high because it is an increase from the value decreased at the second stage low pressure mold clamping start point b. It can be seen from the curve A1 that the movable mold clamping force immediately before the high pressure mold clamping start point c is slightly larger than the value in the section until reaching the first stage low pressure mold clamping start point a.

As described above, in the section from the position where the movable platen position substantially corresponds to the guide pin insertion position 1 to the position where the movable platen position corresponds to the mold contact position m, the value of the movable mold clamping force is maintained at a low value. Therefore, when a foreign matter is caught between the movable mold surface 25 of the movable mold 18 or the fixed mold surface 26 of the fixed mold 16, the resistance of the foreign matter causes the movable platen 1 to move.
4 stops. Therefore, since the mold is not closed, the movable mold surface 25 of the movable mold 18 or the fixed mold 1
The fixed mold surface 26 of 6 is not damaged by the foreign matter. The movable platen position is the mold contact position m.
Even if the foreign matter is small, the movable platen 14 stops due to the resistance of the foreign matter because the value of the movable mold clamping force is maintained at a low value even when approaching the position corresponding to.

Next, when the movable platen position reaches the high-pressure mold clamping start point c, the drive source mold clamping force is increased as indicated by the line B1 so that the movable platen position starts the first-stage low-pressure mold clamping. The value is equal to or larger than the value in the section until reaching the point a. Therefore, the movable mold clamping force has a high value after the high-pressure mold clamping starting point c, as represented by the curve A1.

Here, at the high-pressure mold clamping start point c, the movable mold surface 25 of the movable mold 18 is the fixed mold surface 2 of the fixed mold 16.
Since it substantially corresponds to the position where contact is made with 6, the movable platen position corresponds to the mold clamping force after the high-pressure mold clamping start point c. Therefore, since the mold is effectively clamped by the high mold clamping force, the melted resin is injected at a high pressure to form a cavity (not shown) formed between the movable mold surface 25 and the fixed mold surface 26. Even if the space is filled, resin leakage does not occur. Therefore, the quality of the molded product to be molded is improved.

As described above, in the present embodiment, in the section where the movable platen position approaches the mold closing position k and the toggle magnification rapidly increases, by the time it reaches the position corresponding to the mold contact position m, The drive source mold clamping force is controlled so as to be reduced in multiple stages. Therefore, the value of the movable mold clamping force is maintained at a low value until the movable platen position reaches the position corresponding to the mold contact position m.
Regardless of the size of the foreign matter attached to the movable mold surface 25 of the movable mold 18 or the fixed mold surface 26 of the fixed mold 16, the movable platen 14 stops due to the resistance of the foreign matter. Therefore, the movable mold surface 25 of the movable mold 18 or the fixed mold surface 26 of the fixed mold 16 is not damaged by the foreign matter.

In this embodiment, an example in which the drive source mold clamping force is reduced in two steps has been described, but the drive source mold clamping force can be reduced in three or more steps. In this case, a plurality of low pressure mold clamping start points are set between the first stage low pressure mold clamping start point a and the high pressure mold clamping start point c. For example, when the driving source mold clamping force is reduced in three steps, the first-stage low-pressure mold clamping start point a and the high-pressure mold clamping start point c are equally divided into the second-stage low-pressure mold. A clamping start point and a third stage low pressure mold clamping start point can be set. Further, as the number of steps for separately reducing the driving source mold clamping force increases, the fluctuation of the value of the movable mold clamping force can be reduced.

Next, a second embodiment of the present invention will be described. The description of the same structure and operation as those in the first embodiment will be omitted.

FIG. 7 is a diagram showing a mold clamping method for an injection molding machine according to the second embodiment of the present invention.

In the figure, curve A in graph (a)
Reference numeral 2 represents the relationship between the movable mold clamping force and the movable platen position, and line B2 in the graph (b) represents the relationship between the driving source mold clamping force applied to the crosshead 21 and the movable platen position. It should be noted that a is a low-pressure mold clamping starting point for reducing the mold clamping force.

In the present embodiment, when the movable platen position reaches the low pressure mold clamping start point a, the drive source mold clamping force is reduced stepwise as indicated by the line B2.
Thereafter, in the section from the low pressure mold clamping start point a to the high pressure mold clamping start point c, the drive source mold clamping force is reduced in proportion to the moving distance of the movable platen position.

Therefore, as shown by the curve A2, the movable mold clamping force once decreases at the low pressure mold clamping start point a, which substantially corresponds to the guide pin insertion position l, and then the mold contact position m. Is maintained at a substantially constant value in the section up to the high-pressure mold clamping start point c corresponding to. Here, since the value of the movable mold clamping force reduced in the section from the low pressure mold clamping start point a to the high pressure mold clamping start point c is equal to or more than the minimum movable mold clamping force e, the guide pin 27 and The movable platen 14 does not stop due to the frictional resistance generated between the movable platen 14 and the guide pin insertion hole 28 and the frictional resistance generated between the movable platen 14 and a tie bar (not shown).

As described above, in this embodiment, in the section where the movable platen position approaches the mold closing position k and the toggle magnification rapidly increases, the position corresponding to the mold contact position m is reached. After the driving source mold clamping force is reduced stepwise, it is reduced in proportion to the moving distance of the movable platen position.

Therefore, until the movable platen position reaches the position corresponding to the mold contact position m, the value of the movable mold clamping force is maintained at a substantially constant low value, so that the size of the foreign matter is reduced. Regardless of the position of the movable platen, the movable platen 14 stops due to a certain resistance or more. Therefore, the movable mold surface 25 of the movable mold 18 or the fixed mold surface 26 of the fixed mold 16 is not damaged by the foreign matter.

Next, a third embodiment of the present invention will be described. The description of the same structures and operations as those of the first and second embodiments will be omitted.

FIG. 8 is a diagram showing a mold clamping method for an injection molding machine according to the third embodiment of the present invention.

In the figure, curve A in graph (a)
3 represents the relationship between the movable mold clamping force and the movable platen position, and the line B3 in the graph (b) represents the relationship between the drive source mold clamping force applied to the crosshead 21 and the movable platen position.

In the present embodiment, when the movable platen position reaches the low-pressure mold clamping start point a, the movable platen position moves in the section up to the high-pressure mold clamping start point c as shown by the line B3. The drive source mold clamping force is reduced in proportion to the distance.

Therefore, the movable mold clamping force begins to gradually decrease from the low pressure mold clamping start point a, which substantially corresponds to the guide pin insertion position l, as indicated by the curve A3, and the mold contact position is reached. By the time it reaches the position close to the high-pressure mold clamping start point c corresponding to m, it drops to a low value. here,
The value of the movable mold clamping force reduced at the position close to the high-pressure mold clamping start point c is equal to or more than the minimum movable mold clamping force e, and therefore, between the guide pin 27 and the guide pin insertion hole 28. The movable platen 14 does not stop due to the generated frictional resistance or the resistance such as the frictional resistance generated between the movable platen 14 and a tie bar (not shown).

As described above, in the present embodiment, in the section where the movable platen position approaches the mold closing position k and the toggle magnification rapidly increases, by the time it reaches the position corresponding to the mold contact position m, The drive source mold clamping force is reduced in proportion to the moving distance of the movable platen position.

Therefore, immediately before the movable platen position reaches the position corresponding to the mold contact position m, the value of the movable mold clamping force decreases to a low value, so that the movable platen position becomes the mold contact position m. When approaching, the movable platen 14 stops due to the resistance of the foreign matter. Therefore, the movable mold surface 25 of the movable mold 18 or the fixed mold surface 26 of the fixed mold 16 is not damaged by the foreign matter.

Next, a fourth embodiment of the present invention will be described. The description of the same structure and operation as those of the first to third embodiments will be omitted.

FIG. 9 is a diagram showing a mold clamping method for an injection molding machine according to the fourth embodiment of the present invention.

In the figure, line A4 in graph (a)
Represents the relationship between the movable mold clamping force and the movable platen position,
A curve B4 in the graph (b) represents the relationship between the driving source mold clamping force applied to the crosshead 21 and the movable platen position.

In the present embodiment, when the movable platen position reaches the low pressure mold clamping start point a, the drive source mold clamping force is reduced stepwise as shown by the curve B4. Thereafter, in the section from the low-pressure mold clamping start point a to the high-pressure mold clamping start point c, the drive source mold clamping force is reduced so as to be the reciprocal of the toggle magnification that changes as shown in FIG. 5 or 6.

Therefore, as shown by the line A4, the movable mold clamping force once decreases at the low pressure mold clamping start point a substantially corresponding to the guide pin insertion position l, and then the mold contact position m. Is maintained at a completely constant value in the section up to the high-pressure mold clamping start point c corresponding to. Here, since the value of the movable mold clamping force reduced in the section from the low pressure mold clamping start point a to the high pressure mold clamping start point c is equal to or more than the minimum movable mold clamping force e, the guide pin 27 and The movable platen 14 does not stop due to the frictional resistance generated between the movable platen 14 and the guide pin insertion hole 28 and the frictional resistance generated between the movable platen 14 and a tie bar (not shown).

As described above, in the present embodiment, in the section where the movable platen position approaches the mold closing position k and the toggle magnification rapidly increases, by the time it reaches the position corresponding to the mold contact position m, After the driving source mold clamping force is reduced stepwise, it is reduced to the reciprocal of the toggle magnification.

Therefore, until the movable platen position reaches the position corresponding to the mold contact position m, the value of the movable mold clamping force is maintained at a completely constant low value, and the size of the foreign matter is reduced. Regardless of the position of the movable platen, regardless of the position of the movable platen, the movable platen 14 is stopped by a certain resistance or more. Therefore, the movable mold surface 25 of the movable mold 18 or the fixed mold surface 26 of the fixed mold 16 is not damaged by the foreign matter.

In the above first to fourth embodiments, the horizontal type injection molding machine in which the movable platen moves in the lateral direction (horizontal direction) has been described, but the mold clamping device and method of the present invention are as follows. It can also be applied to a vertical type injection molding machine in which the movable platen moves in the vertical direction (vertical direction). Further, the mold clamping device and method of the present invention can be applied to a molding machine such as a die cast machine and an IJ sealing press, in addition to the injection molding machine.

Further, the present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention, and they are not excluded from the scope of the present invention.

[0090]

As described above in detail, according to the present invention, in the mold clamping device of the injection molding machine, the mold device including the fixed mold and the movable mold and the movable mold are supported. A movable mold support member and a crosshead, a base end portion of which is attached to the toggle mechanism support member, and a tip end portion of which is attached to the movable mold support member, and a drive source which moves the crosshead, When the movable mold support member is advanced to perform mold clamping, when the position of the movable mold support member enters a section where the toggle ratio of the toggle mechanism increases, the mold clamping force of the drive source is gradually reduced. And a control device.

According to the present invention, in the mold clamping method for the injection molding machine, the drive source is operated to move the crosshead forward to operate the toggle mechanism, and the movable metal member attached to the tip of the toggle mechanism is operated. When the movable mold support member supporting the mold is advanced and the position of the movable mold support member enters a section where the toggle magnification of the toggle mechanism increases, the mold clamping force of the drive source is gradually reduced.

In this case, the mold clamping force of the movable mold is maintained at a low value until the movable mold support member reaches the position where the fixed mold and the movable mold come into contact with each other. Regardless of the size of the foreign matter attached to the movable mold surface of the mold or the fixed mold surface of the fixed mold, the movable mold support member stops due to the resistance of the foreign matter. Therefore, the movable mold surface of the movable mold or the fixed mold surface of the fixed mold is not damaged by the foreign matter.

[Brief description of drawings]

FIG. 1 is a diagram showing a mold clamping method of an injection molding machine according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a mold clamping method of a conventional injection molding machine.

FIG. 3 is a schematic diagram showing a mold closing state of the mold clamping device of the injection molding machine according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram showing a state of the mold clamping device of the injection molding machine when the mold is opened according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a position of a movable platen and a toggle magnification in the toggle mechanism according to the first embodiment of the present invention.

FIG. 6 is an enlarged view of a portion K in FIG. 5 according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a mold clamping method for an injection molding machine according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a mold clamping method for an injection molding machine according to a third embodiment of the present invention.

FIG. 9 is a diagram showing a mold clamping method for an injection molding machine according to a fourth embodiment of the present invention.

[Explanation of symbols]

10 injection molding machine 13 Toggle support 14 Movable platen 16 Fixed mold 18 movable mold 20 toggle mechanism 21 crosshead

Claims (10)

[Claims] 1. A base device, comprising: (a) a mold device including a fixed mold and a movable mold; (b) a movable mold supporting member supporting the movable mold; and (c) a crosshead. Is attached to a toggle mechanism support member, and a tip end portion is attached to the movable mold support member, (d) a drive source for moving the crosshead, and (e) forward movement of the movable mold support member. When performing mold clamping with a mold, when the position of the movable mold supporting member enters a section where the toggle magnification of the toggle mechanism increases, a controller for gradually reducing the mold clamping force of the drive source is provided. Clamping device for injection molding machine. 2. The mold clamping device for an injection molding machine according to claim 1, wherein the control device reduces the mold clamping force of the drive source in a plurality of stages. 3. The mold clamping device for an injection molding machine according to claim 1, wherein the control device reduces the mold clamping force of the drive source in proportion to the moving distance of the movable mold supporting member. 4. The mold clamping device for an injection molding machine according to claim 1, wherein the control device reduces the mold clamping force of the drive source so as to become an inverse number of a toggle magnification. 5. The control device lowers the mold clamping force of the drive source so that the mold clamping force of the movable mold becomes equal to or more than the minimum movable mold clamping force. Clamping device for the injection molding machine described. 6. A movable mold support member for supporting a movable mold attached to a tip of the toggle mechanism by (a) operating a drive source to move a crosshead forward to operate a toggle mechanism. The mold of the injection molding machine is characterized in that (c) the mold clamping force of the drive source is gradually reduced when the movable mold support member is advanced (c) into a section where the toggle ratio of the toggle mechanism increases. Tightening method. 7. The mold clamping method for an injection molding machine according to claim 6, wherein the mold clamping force of the drive source is reduced in a plurality of stages. 8. The mold clamping method for an injection molding machine according to claim 6, wherein the mold clamping force of the drive source is reduced in proportion to the moving distance of the movable mold supporting member. 9. The mold clamping method for an injection molding machine according to claim 6, wherein the mold clamping force of the drive source is reduced to be an inverse number of a toggle magnification. 10. The injection molding according to claim 6, wherein the mold clamping force of the drive source is reduced so that the mold clamping force of the movable mold becomes equal to or more than the minimum movable mold clamping force. Machine clamping method.