JPH04249127A - Injection molding machine - Google Patents

Abstract

PURPOSE:To make the whole of an injection molding machine small and retain the mold clamping state when driving force is discontinued. CONSTITUTION:A motor 26 of a mold opening and closing mechanism 20 is started and a ball nut 24 screwed with a male screw 25 is rotated. A movable platen 15 is moved by said arrangement to move a movable mold 17 close to a fixed mold 16. After that, a motor 34 of a mold clamping mechanism 21 is started, and a male screw 32 screwed with a female screw 33 is rotated. A movable platen 15 is moved by said arrangement to press the molvable mold 15 to the fixed motor 16 to form the mold clamping state. Molten plastic is injected into a molding tool in said state. Large force in the opening direction applied to the movable mold is received by a male screw 25 through a ball nut 24 by the pressure applied to the molten plastic.

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 having a screw mechanism for opening and closing the mold, and for clamping and releasing the mold.

0002

2. Description of the Related Art In an injection molding machine, a movable mold and a fixed mold are attached to a movable platen and a fixed platen, and the movable platen is moved back and forth to open and close the mold, clamp the mold, and release the mold.

In this injection molding machine, the movable platen is generally driven by a hydraulic cylinder, and during molding, the hydraulic cylinder is operated at high speed to move the movable platen close to the fixed mold at high speed (mold closing operation ), then the hydraulic cylinder is operated at low speed to tighten the movable mold to the fixed mold, and in this tightened state, molten plastic is injected into the mold to perform molding.

[0004] In this hydraulic cylinder method, when the movable platen is moved at high speed and the mold is closed, a large amount of hydraulic oil must be supplied to the hydraulic cylinder at a low pressure. High-pressure hydraulic oil must be continuously supplied to the hydraulic cylinder to prevent the movable platen from retreating due to the pressure of the plastic. For this reason, a hydraulic pump with a large maximum discharge amount and maximum pressure is required. Furthermore, since a hydraulic cylinder with a large stroke necessary for opening and closing the mold must be installed, the injection molding machine as a whole becomes large.

[0005] In order to overcome the drawbacks of the hydraulic cylinder type, there is a type using a toggle mechanism. As shown in FIG. 7, this has a structure in which a nut 3 is screwed onto a screw member 2 rotated by a motor 1, and this nut 3 is connected to a toggle mechanism 4 via a link 5. In this device, when the nut 3 is moved in the direction of arrow A by the rotation of the screw member 2, the links 4a and 4 of the toggle mechanism 4
b extends from the bent "dog" shape, the movable platen 6 (movable mold 7) moves toward the fixed mold 8 due to the extension of the links 4a and 4b, and the links 4a and 4b extend straight. As a result, the movable mold 7 is tightened to the fixed mold 8 with a large force.

However, with this toggle mechanism method,
Since the links 4a and 4b extend substantially straight to produce a large tightening force, the thicknesses of the movable mold 7 and the fixed mold 8 must be adjusted accurately. Both types 7
, 8, if the thickness adjustment is inaccurate, sufficient tightening force may not be obtained, or the mold may be damaged by tightening with excessive force.

[0007]

[Problems to be Solved by the Invention] As mentioned above, in the case of the hydraulic cylinder type, the entire molding machine becomes large;
Moreover, a high-output hydraulic pump must be used,
Furthermore, there is a problem in that the hydraulic pump must continue to be driven at high output during molding, and in the case of the toggle mechanism method, the thickness of the movable and fixed molds must be adjusted accurately, which can lead to insufficient or over-tightening. There is a problem in that it is easy to cause problems.

The present invention has been made in view of the above circumstances, and its objects are to avoid increasing the overall size, and to maintain the mold in a tightened state without continuing to drive the drive source during molding. Furthermore, it is an object of the present invention to provide an injection molding machine that does not require accurate thickness adjustment of a movable mold and a fixed mold in relation to mold clamping force.

[0009]

Means for Solving the Problems To achieve the above object, an injection molding machine according to claim 1 includes: a first mounting plate to which one of the molds is attached; a movable moving base; A second mounting plate is connected to the movable base so that it can move integrally with the movable base and can also move independently, and has the other mold of the mold attached thereto, and a male threaded member and a second mounting plate that is screwed together with the male threaded member. One of the male threaded member and the female threaded member is provided on the molding machine main body side, and the other is provided on the movable base side, and is moved by rotating either the male threaded member or the female threaded member in a forward or reverse direction. A mold opening/closing mechanism that opens and closes the mold by reciprocating the base together with a second mounting plate, a male threaded member and a female threaded member that is threadedly engaged with the male threaded member, and one of the male threaded member and the female threaded member is moved as described above. One is provided on the base body side, and the other is provided on the second mounting board side, and by rotating either the male thread member or the female thread member in forward and reverse directions, the second mounting board is independently reciprocated to move the mold. It consists of a mold clamping mechanism that tightens and releases the clamp.

The injection molding machine according to a second aspect of the present invention includes a movable first mounting plate to which one of the molds is attached, and a movable second mounting plate to which the other mold of the molds is attached. and a male threaded member and a female threaded member screwed into the male threaded member, one of the male threaded member and the female threaded member is provided on the molding machine main body side, and the other is provided on the second mounting board side, and the male threaded member and the female threaded member are provided. A mold opening/closing mechanism that opens and closes the mold by reciprocating a second mounting plate by rotating one of the female thread members forward and backward; a male thread member; and a female thread member that is screwed with the male thread member; One of the male threaded member and the female threaded member is provided on the molding machine main body side, and the other is provided on the first mounting board side, and by rotating either the male threaded member or the female threaded member forward or backward, the first The mold clamping mechanism reciprocates the mounting plate to clamp and release the clamping of the mold.

[0011]

[Operation] Since the male threaded member and the female threaded member are used to open and close the mold, and to clamp and release the mold, an increase in size can be avoided, unlike those driven by hydraulic cylinders. Also, unlike those driven by a toggle mechanism, there is no need to accurately adjust the thickness of the movable type and the fixed type.

Moreover, since the pressure applied to the molten plastic is received by the screw mechanism, there is no need to maintain the screw mechanism in a driven state once the mold is clamped.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 4 showing the overall configuration of an injection molding machine, a fixed plate 12 as a first mounting plate and a support plate 13 are disposed facing each other on a base 11 as the molding machine body. There is. For example, four tie bars 14 are fixed between the fixed plate 12 and the support plate 13, and a movable plate 15 as a second mounting plate is movably supported by the tie bars 14. A fixed mold 16 (one mold) and a movable mold 17 (the other mold) of molding molds are attached to the fixed platen 12 and the movable platen 15. Further, an injection device 18 is movably disposed on the base 11, and when the mold is clamped as described later, this injection device 18 is moved to the fixed platen.
The nozzle 19 at the tip is connected to a locate ring (not shown) of the fixed mold 16 by moving to the second side.

FIG. 1 shows a mold opening/closing mechanism 20 for moving the movable platen 15 to perform opening/closing operations and a mold clamping mechanism 21 for performing a mold clamping operation. First, in the mold opening/closing mechanism 20, a bracket 22 is attached to the movable platen 15, and a total of four movable base bodies are inserted and supported by each tie bar 14, spanning the bracket 22 and the movable platen 15. A sleeve 23 is rotatably provided. This sleeve 23 is movable in the axial direction with respect to the tie bar 14, and the movable platen 15 and bracket 22 are connected to this sleeve 23 so as to be movable within a range of several millimeters. and,
A ball nut 24 as a female threaded member is fixed to the left side of the sleeve 23 in the drawing, and this ball nut 24 is screwed into a male thread 25 formed on the left half portion of the tie bar 14 as a male threaded member.

A motor 26 equipped with a speed reducer and serving as a driving source for the mold opening/closing mechanism 20 is attached to a bracket 22 . A gear 27 is attached to a rotating shaft 26a of the motor 26, and this gear 27 meshes with a gear 28 formed on the sleeve 23. Therefore, when the motor 26 starts, its rotation is transmitted to the sleeve 23 through the gears 27 and 28.
This is then transmitted to the ball nut 24. According to the rotational direction of the ball nut 24, the movable platen 15 and the sleeve 23 move toward the fixed platen 12 in the direction indicated by arrow B and in the direction away from the fixed platen 12, which is opposite to arrow B. Note that in reality, as shown in FIG. 2, only two motors 26 are provided for four ball nuts 24, and one motor 26 drives two ball nuts 24. . At this time, an intermediate gear 29 is provided between the gears 28 driven by separate motors 26 so that all the ball nuts 24 rotate synchronously.

On the other hand, in the mold clamping mechanism 21, an inner cylindrical body 30 as a male threaded member is rotatably provided on the outside of each sleeve 23. In addition, the movable platen 15 has an inner cylindrical body 3.
An outer cylindrical body 31 as a female threaded member surrounding 0 is fixed. A male thread 32 made of a trapezoidal thread is formed on the outer periphery of the inner cylindrical body 30, and is screwed into a female thread 33 formed on the inner periphery of the outer cylindrical body 31, also made of a trapezoidal thread.

A motor 34 equipped with a reduction gear and serving as a driving source for the mold clamping mechanism 21 is attached to the bracket 22. A gear 35 is attached to a rotating shaft 34a of the motor 34, and this gear 35 meshes with a gear 36 formed on the inner cylinder body 30. Therefore, when the motor 34 starts, its rotation is transmitted to the inner cylinder 30 through the gears 35 and 36.
can be conveyed to. Then, depending on the rotation direction of the inner cylinder 30, the outer cylinder 31 and the movable plate 15 are independently rotated to the fixed plate 1.
is moved in the direction of arrow B and in the opposite direction to arrow B. This is because the ball nut 24 is screwed into the male thread 25 of the tie bar 14, so that the male thread 25 receives the thrust load acting on the inner cylinder 30 and prevents the sleeve 23 from moving. 15 moves independently in the direction of arrow B or in the opposite direction to arrow B. At this time, the bracket 22 also moves together with the movable platen 15, but the movement of the bracket 22 is allowed by the teeth of the gear 27 sliding against the teeth of the gear 28.

Note that, as shown in FIG. 3, four inner cylinders 30
In contrast, only two driving motors 34 are provided, and one motor 34 drives two inner cylindrical bodies 30. At this time, an intermediate gear 37 is provided between gears 36 driven by separate motors 34 so that all the inner cylindrical bodies 30 rotate synchronously.

In the injection molding machine having the above configuration, when the motor 26 of the mold opening/closing mechanism 20 starts and rotates in the forward direction in the mold opening state shown in FIG. 4, the sleeve 23 and thus the ball nut 24 rotate in the forward direction. The board 15 moves at high speed in the direction of arrow B. Then, when the movable mold 17 reaches a position on the verge of contacting the fixed mold 16 (this position is detected by a limit switch or the like), the motor 26 stops. After this, the motor 34 of the mold clamping mechanism 21 is activated and rotates in the forward direction. This rotates the inner cylindrical body 30 in the forward direction, and the male thread 32 is strongly tightened against the female thread 33 of the outer cylindrical body 31. Then, the movable platen 15 moves in the direction of arrow B, and the movable mold 17 comes into contact with the fixed mold 16 and is strongly pressed, resulting in a mold clamping state. In addition, the movable plate 15 at this time
The amount of movement is on the order of several millimeters.

When the mold is clamped in this way, the injection device 18 advances and connects the nozzle 19 to a locate ring (not shown) of the fixed mold 16. After that, nozzle 19
Molten plastic is injected and molded. During such molding, high pressure is applied to the molten plastic, so that the movable mold 17 receives a large force in the direction of separating from the fixed mold 16. This separation force acts on the ball nut 24 via the movable platen 15 and the sleeve 23, and is finally received by the male thread 25 of the tie bar 14.

Now, when the molding is completed, the mold clamping mechanism 21
The motor 26 rotates in reverse, and the male screw 32 of the inner cylinder 30 is loosened. Then, the movable platen 15 moves several millimeters in the opposite direction to the arrow B, and the movable mold 17 separates from the fixed mold 16. Thereafter, the motor 26 of the mold opening/closing mechanism 20 is reversely rotated to move the movable platen 15 in the direction opposite to the arrow B at high speed. As a result, the movable mold 17 is separated from the fixed mold 16 and becomes in an open state, and in this mold open state, an extrusion mechanism (not shown) operates to extrude the molded product.

As described above, according to the present embodiment, the mold opening/closing mechanism 20 and the mold clamping mechanism 21 are constituted by screw mechanisms driven by the motors 26 and 34, so that the movement of the movable platen 15 for opening and closing the mold is Unlike a hydraulic cylinder that has a stroke as large as a distance, an increase in size can be avoided. Moreover, by setting the reduction ratio of the motor 26 to a small value, the ball nut 24 can be rotated at high speed, and the movable platen 15 can be opened and closed at a high speed, and the reduction ratio of the motor 34 can be set to a large value. This allows high torque to be transmitted to the inner cylindrical body 30 and the movable mold 16 to be strongly tightened to the fixed mold 17, so unlike the hydraulic cylinder type, the motors 26 and 34 serving as the drive source do not have to have high output. I can get away with it.

Furthermore, the large pressure exerted on the movable mold 17 from the molten plastic during molding is received by the ball nut 24 and the male thread 25 of the tie bar 14, so once the movable mold 17 is tightened to the fixed mold 16, the mold Even if the motor 34 of the tightening mechanism 21 is not kept in a driving state, the movable die 17 and the fixed die 16 can be strongly tightened, and power consumption can be reduced.

Furthermore, since mold clamping is not performed by a toggle mechanism, there is no need to adjust the thicknesses of the fixed mold 16 and the movable mold 17 in order to generate strong mold clamping force.

FIG. 5 shows a second embodiment of the present invention, in which the same parts as in the above-described first embodiment are given the same reference numerals, and different parts will be explained. This second embodiment differs from the first embodiment described above in that a clamping force is applied to the central portion of the movable platen 15 by a mold clamping mechanism 21.

First, the movable platen 15 is movably supported by the tie bar 14 via a bearing 38. Further, the bracket 39 is movably supported by the tie bar 14 via a sleeve 40 serving as a movable base to which the ball nut 24 is fixed. In this case, the bracket 39 is configured so that it cannot move in the axial direction with respect to the sleeve 40. The rotation of the motor 26 of the mold opening/closing mechanism 20 is controlled by the gear 41.
and 42 to the sleeve 40.

On the other hand, in the center of the bracket 39, an inner cylindrical body 43 as a male threaded member of the mold closing mechanism 21 is rotatably supported by a shaft 44, and a male thread 45 is provided on the outer periphery of the inner cylindrical body 43. It is formed. Further, an outer cylinder 46 as a female threaded member surrounding the inner cylinder 43 is attached to the center of the movable platen 15, and the male thread 45 of the inner cylinder 43 is attached to the inner circumference of the outer cylinder 46. A female thread 47 is formed to be screwed together. By screwing the male thread 45 and the female thread 47, the movable platen 15 is connected to the sleeve 40 via the bracket 39, and moves together with the sleeve 40 when the mold is opened and closed. And the mold clamping mechanism 21
A motor 34 serving as a driving source is attached to a bracket 39, and a gear 48 attached to its rotating shaft 34a meshes with a gear 50 formed on the outer cylindrical body 46 via an intermediate gear 49.

In the above configuration, when the motor 26 of the mold opening/closing mechanism 20 rotates in the forward direction, the ball nut 24 rotates in the forward direction, and the bracket 39 and the movable platen 15 integrally move toward the fixed platen 12 side. do. Next, the motor 34 of the mold clamping mechanism 21 rotates in the forward direction, and the inner cylindrical body 43 rotates in the forward direction. As a result, the movable platen 15 moves away from the bracket 39, and the movable mold 17 is strongly fastened to the fixed mold 16.

After molding, when the motor 34 of the mold clamping mechanism 21 rotates in the opposite direction, the movable platen 15 moves toward the bracket 39, and the movable mold 17 is unfastened. Thereafter, as the motor 26 of the mold opening/closing mechanism 20 rotates in the opposite direction, the bracket 22 and the movable platen 15 move together, and the mold is opened. Even with this configuration, the same effects as in the first embodiment described above can be obtained.

FIG. 6 shows a modification of the second embodiment of the present invention, which differs from the first embodiment described above in that a mold is provided in place of the fixed platen 12 of the first embodiment. The mold is clamped by moving the mounting plate 51 (first mounting plate) toward the movable platen 15.

The same parts as in the first embodiment will be given the same reference numerals and only the different parts will be explained below.The movable platen 15 is supported by the tie bar 14 via a sleeve 52 to which a ball nut 24 is fixed. . The sleeve 52 is rotationally driven by a motor 26 attached to the movable platen 15 via gears 53 and 54.

On the other hand, a bush 56 as a male threaded member of a mold clamping mechanism 55 is rotatably attached to one end of the tie bar 14, and a male thread 57 is formed on the outer periphery of this bush 56. Further, a cylinder body 58 as a female screw member is rotatably provided on the mold placement plate 51.
A female thread 5 screwed into the male thread 57 on the inner circumference of this cylinder 58
9 is formed. Then, the mold placement plate 51 is connected to the tie bar 1.
4, a motor 34 is attached to this mold stand 51, and a rotation shaft 34 of this motor 34
The gear 60 attached to a is formed on the cylindrical body 58.
It meshes with 1.

In the above configuration, when the motor 26 of the mold opening/closing mechanism 20 rotates in the forward direction, the ball nut 24 rotates in the forward direction, thereby moving the movable platen 15 toward the mold placement plate 51. When the movable mold 17 comes to a position on the verge of contacting the fixed mold 16, the motor 26 stops. After this, the motor 34 of the mold clamping mechanism 55 is activated and rotates in the forward direction. As a result, the cylinder 58 rotates in the forward direction, and the female screw 59 is strongly tightened against the female screw 59 of the bush 56. Then, the mold placement plate 51 moves toward the movable plate 15, and the fixed mold 16 is strongly pressed against the movable mold 17, resulting in a mold clamping state. Note that the amount of movement of the mold placement plate 51 at this time is approximately several millimeters. Even with this configuration, the same effects as in the first embodiment described above can be obtained.

[0035]

Effects of the Invention As explained above, according to the present invention, since the mold is opened, closed and clamped by a screw mechanism, it is possible to avoid increasing the size of the entire mold, and the molding mold can be easily moved without continuously driving the drive source during molding. This has excellent effects such as being able to maintain the mold in a tightened state, and further eliminating the need to accurately adjust the thickness of the movable mold and the fixed mold in relation to the mold clamping force.

[Brief explanation of the drawing]

FIG. 1 is an enlarged longitudinal cross-sectional side view showing a first embodiment of the present invention.

[
Figure 2: Side view showing the rotation transmission configuration of the mold opening/closing mechanism

[Figure 3]
Side view showing the rotation transmission configuration of the mold clamping mechanism

[Figure 4] Overall side view

[Fig. 5] A diagram corresponding to Fig. 1 showing a second embodiment of the present invention.

[Figure 6
]A diagram corresponding to FIG. 1 showing a third embodiment of the present invention

[Fig. 7] Schematic configuration diagram showing an example of a conventional mold opening/closing mechanism and mold clamping mechanism

[Explanation of symbols]

12 is a fixed plate (first mounting plate), 14 is a tie bar (externally threaded member), 15 is a movable plate (second mounting plate), 16 is a fixed type, 17 is a movable type, 20 is a mold opening/closing mechanism, and 21 is a Mold clamping mechanism, 22 is a bracket, 24 is a ball nut (femally threaded member), 26 is a motor, 30 is an inner cylinder (femally threaded member), 3
1 is an outer cylinder (male thread member), 34 is a motor, 40 is a sleeve (moving base), 43 is an inner cylinder (male thread member), 46
51 is the mold mounting plate (first mounting plate), 55 is the mold clamping mechanism, and 56 is the bush (male threaded member).
, 58 is a cylinder (femally threaded member).

Claims (2)

[Claims] Claim 1: A first mounting plate to which one of the molding molds is attached, a movable movable base, and a movable base capable of moving integrally with the movable base and also capable of moving independently. A second mounting board is connected to the mold and has the other mold attached thereto, a male threaded member and a female threaded member screwed into the male threaded member, and one of the male threaded member and the female threaded member is provided on the side of the molding machine main body. and a mold opening/closing mechanism, the other of which is provided on the movable base side, and which opens and closes the mold by reciprocating the movable base together with a second mounting plate by rotating either the male threaded member or the female threaded member forward or backward; a male threaded member and a female threaded member screwed into the male threaded member; one of the male threaded member and the female threaded member is provided on the movable base side and the other is provided on the second mounting board side; An injection molding machine comprising a mold clamping mechanism that independently reciprocates a second mounting plate by rotating one of the members in forward and reverse directions to clamp and release the clamping of the mold. 2. A movable first mounting plate to which one of the molds is attached, a movable second mounting plate to which the other mold is attached, a male threaded member, and the male threaded member. The male thread member and the female thread member are provided with a female thread member to be screwed together, one of the male thread member and the female thread member is provided on the molding machine main body side, and the other is provided on the second mounting board side, and either of the male thread member or the female thread member can be rotated in the forward or reverse direction. A mold opening/closing mechanism that opens and closes the mold by reciprocating a second mounting plate by rotating it, a male threaded member and a female threaded member that is threadedly engaged with the male threaded member, and one of the male threaded member and the female threaded member. One is provided on the molding machine main body side, and the other is provided on the first mounting board side, and by rotating either the male thread member or the female thread member forward or backward, the first mounting board is reciprocated and the mold is attached to the mold. An injection molding machine equipped with a mold clamping mechanism that tightens and releases the clamping mechanism.