JPH08156040A - Ejector mechanism of injection molding machine - Google Patents

Abstract

PURPOSE: To strengthen rigidity of a guide rod guiding an ejector rod. CONSTITUTION: Tips of cantilever beam shaped guide rods 8, 8 disposed in upright on a rear face of a moving platen 2 are fixed to each other with a connecting component 16. Since force acting in a radial direction of the guide rods 8, 8 is divided into force bending or vibrating the guide rods 8, 8 themselves and force straining fixed parts A, A of the guide rods 8, 8 to the connecting component 16, force bending or vibrating the guide rods 8, 8 themselves is relatively decreased to suppress occurrence of bending or vibrating of the guide rods 8, 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of an ejector mechanism of an injection molding machine.

[0002]

2. Description of the Related Art An ejector mechanism for an injection molding machine, which uses a guide rod provided upright on the back surface of a moving Latin to guide the projecting / retracting motion of an ejector rod, is already known. The guide rod that guides the ejector rod is generally fixed by erected only one end on the back surface of the moving Latin, and the structure that supports the guide rod in a cantilever shape is basically the guide rod. It has the drawback of being weak against bending caused by the force acting in the radial direction of the rod. There is no particular problem in the ejector mechanism that directly drives the ejector rod in the axial direction by the piston of the hydraulic cylinder, but in the ejector mechanism that drives the ball screw, ball nut, etc. attached to the ejector rod by power transmission means such as a timing belt. ,
The guide rod that guides the ejector rod receives a force acting from a power transmission means such as a timing belt to generate bending or vibration, which may adversely affect the normal projecting / retracting operation of the ejector rod.

FIG. 1 schematically shows a structure of a conventional ejector mechanism 100 in which a ejector rod 3 is caused to perform a projecting / retracting operation by driving a ball screw, a ball nut or the like by a power transmission means such as a timing belt. FIG. In FIG. 1, reference numeral 2 is a moving platen, and a mold mounting surface 2a formed of a highly accurate flat surface is formed on the front side thereof. This moving platen 2
Is slidably attached to a tie bar of an injection molding machine, and staples 15 and 1 integrally fixed to the back surface of the tie bar.
The mold mounting surface 2a is connected to and separated from the stationary platen of the injection molding machine in response to the mold opening operation of the mold clamping mechanism. A through hole 13 is formed in a substantially central portion of the die mounting surface 2a, and an ejector rod 3 for pressing the ejector plate of the die is provided in the through hole 13 so as to project and retract. The ejector rod 3 is composed of a small-diameter tip portion 3a that is allowed to project from the die mounting surface 2a and a base portion 3b formed of a ball screw.
The base portion 3b is screwed to the inner peripheral surface of a ball nut 4 rotatably and axially immovably attached to the back surface of the moving platen 2 via a retainer 4a and bolts 5 and 5 via a rigid ball.

Further, a base portion 3 penetrating the ball nut 4 and protruding in a direction away from the back surface of the moving platen 2 is formed.
At the end portion of b, knockout bars 7 in which sleeves 6 and 6 are press-fitted and fixed in through holes at both ends are fixed to the ejector rod 3 by bolts 14 so as not to be rotatable and axially movable. The inner peripheral surface of the above is slidably fitted to the outer peripheral surfaces of the guide rods 8, 8 provided upright on the back surface of the moving platen 2.

In the example shown in FIG. 1, the main parts of the guide rods 8 and 8 are constituted by the long sleeves 9 and 9 each having a flange-shaped large diameter part 9a and 9a for preventing the knockout bar 7 from coming off. The long bolts 10, 10 penetrating the long sleeves 9, 9 are passed through the sleeves 9, 9, and the female screws 11, 11 engraved on the back surface of the moving platen 2 are attached to the tips of the long bolts 10, 10. It is shown that the guide rods 8, 8 composed of these members (9, 10) are fixed to the back surface of the moving platen 2 in a cantilever shape by screwing and fastening. Also, a male screw is integrally formed on the base portion of the solid guide rods 8, 8 and the male screw is directly screwed to the female screw 11, 11 of the moving platen 2 to be fixed. Mold for moving platen 2 A through hole with a counterbore is bored from the side of the mounting surface 2a, a bolt is inserted therethrough, and the bolt is screwed into a female screw engraved on the end face of the guide rod 8 on the base side. There is a device in which 8 is fixed. Both are the same in that the guide rods 8 and 8 are fixed to the back surface of the moving platen 2 in a cantilever shape.

The ball nut 4 attached to the back surface of the moving platen 2 is integrally provided with a pulley 12 forming a part of a power transmission means, and an electric motor attached to one side of the moving platen 2. A timing belt (not shown), which constitutes a part of the power transmission means, is wound between the output shaft (not shown) and the pulley 12. In other words, by driving the electric motor to rotate the ball nut 4 via the timing belt and the pulley 12, the guide rods 8 and 8 are engaged with the knockout bar 7 so that the moving platen 2 cannot rotate. The ejector rod 3 is axially fed so that the tip portion 3a of the ejector rod 3 is projected or retracted from the mold mounting surface 2a.

At this time, the movement direction of the ejector rod 3 is slidable between the small diameter portion of the through hole 13 of the moving platen 2 and the tip portion 3a of the ejector rod 3 which are in close contact with the tip portion 3a of the ejector rod 3. Three-point support (the guide rod 8 has two guide rods 8 and 8), and the knock-out bar 7 fixed to the end of the base portion 3b of the ejector rod 3 and the guide rods 8 and 8 are slidably fitted together. However, if the rigidity of the guide rods 8, 8 is low, the ball nut 4 is eccentric due to the tension of the timing belt wound around the pulley 12, and the base portion 3b of the ejector rod 3 is in the radial direction. Further, the position of the knockout bar 7 fixed to the base portion 3b of the ejector rod 3 may be eccentric and the guide rods 8 may be bent. When the ball nut 4 is rotated forward and backward in small steps at high speed to repeat a plurality of projecting and retracting operations, the rotation direction of the ball nut 4 is switched, that is, the direction of the tension applied by the timing belt. Changes in the guide rods 8 and 8 cause inadvertent vibrations, and screwing means (eg, bolts 5, 1
(0, 14 etc.) will be loosened. Of course, the guide rods 8 and 8 are members that are absolutely necessary to prevent rotation of the ejector rod 3 and to maintain its rectilinear movement, and it is impossible to omit this structurally.

In order to cope with such bending and vibration, the diameter of the guide rods 8, 8 is increased to increase the rigidity, or the number of the guide rods 8 provided is increased to substantially increase the rigidity ( In this case, the shape change of the knockout bar 7 is required), but in any case, there is a problem that the manufacturing cost of the ejector mechanism 100 increases due to the increase in the diameter of the guide rod 8 and the increase in the number thereof. .

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a guide rod for guiding an ejector rod that is simple and inexpensive and does not increase the manufacturing cost. It is to provide an ejector mechanism of a molding machine.

[0010]

According to the present invention, one end of a plurality of guide rods is erected on the back surface of a moving platen to guide a projecting / retracting operation of an ejector rod, and a power transmitting means for driving the ejector rod. In the ejector mechanism of the injection molding machine in which the acting force is received in the radial direction by the guide rod, the other end portion of each ejector rod is integrally fixed by a connecting member.

[0011]

Since the other ends of the plurality of guide rods erected on the back surface of the moving platen are integrally fixed via the connecting member, the substantial rigidity of the guide rod is increased, and the guide rod is bent or vibrated. Is prevented from occurring. That is, the force that acts from the power transmission means in the radial direction of the guide rod is divided into a force that bends or vibrates the guide rod itself and a force that distorts the fixing portion between the guide rod and the connecting member. The force that bends or vibrates the guide rod itself is relatively reduced, and the occurrence of bending and vibration is suppressed.

[0012]

FIG. 2 is a side sectional view schematically showing the construction of an ejector mechanism 1 of one embodiment to which the present invention is applied. An embodiment of the present invention will be described below with reference to this drawing. In addition,
The ejector mechanism 1 of the embodiment is the same as the conventional ejector mechanism 100 shown in FIG. 1 with respect to all means for realizing the projecting / retracting operation of the ejector rod 3, and therefore, detailed description will be made regarding the configuration and function of the common parts. Are omitted, and only the same symbols as those used in the description of FIG. 1 are given.

The ejector mechanism 1 of this embodiment differs from the conventional ejector mechanism 100 in that the connecting member 16
Is that the tips of the guide rods 8 are fixed to each other.

The connecting member 16 is composed of a strip-shaped flat plate, and has bolt through holes 16a, 16 formed at both ends thereof.
Through a, they are fastened together with long bolts 10 to the tips of long sleeves 9 forming the main part of the guide rods 8. When solid guide rods are used as the guide rods 8, 8, female threads are formed on the tip surfaces of the guide rods 8, 8 and the connecting member 16 is attached to the guide rods 8, 8 using an appropriate bolt or the like. Be sure to fix it directly to the tip surface of.

Further, the strength of the connecting portion can be increased by welding the tip end portions of the guide rods 8, 8 and the peripheral portions of the bolt through holes 16a, 16a in the connecting member 16. However, the connection method using welding together is performed in the embodiment shown in FIG. 2 and by forming a through hole with a counterbore from the side of the mold mounting surface 2a of the moving platen 2 and inserting a bolt to make a solid connection. The guide rods 8, 8 are moved to the moving platen 2 by means of female screws on the end faces on the base side of the guide rods 8, 8.
Although it is effective for the configuration in which it is fixed to the back surface of the solid guide rod 8, a male screw is integrally formed on the base portion of the solid guide rods 8, 8 to form a female screw 11,
In the case where the guide rods 8 and 8 are directly screwed together, the rotation operation for releasing the screwing, which is necessary for the attachment / detachment of the guide rods 8, becomes impossible. Therefore, it is not always desirable in consideration of maintenance and the like.

In the embodiment shown in FIG. 2, since the connecting member 16 also serves as a retainer for the knockout bar 7, it is essential to form the large diameter portion 9a at the tip of the long sleeve 9 as shown in FIG. However, as described above, when relying only on fixing means such as bolts to connect the tip end portions of the guide rods 8 and 8 to the connecting member 16, a large portion as shown in FIG. It is desirable to form the diameter portion 9a or a large diameter portion 9a having a diameter larger than that at the tip end portion of the guide rods 8,8. As long as the force for fastening the connecting member 16 to the guide rods 8 and 8 with the bolts is the same, the larger the diameter of the tip surface of the guide rods 8 and 8, that is, the larger the diameter of the large diameter portion 9a, the more the guide rods 8 and 8 are connected. This is because the orthogonal state with the connecting member 16 is reliably maintained (meaning that a large force is required to cause distortion in the portions indicated by arrows A and A in FIG. 2).

As already described in the section of the prior art, when the ejector rod 3 is projected and retracted, an electric motor (not shown) is driven and a timing belt (not shown) and a pulley 12 are used. By rotating the ball nut 4, the ejector rod 3 is fed in the axial direction. At this time, if the rigidity of the guide rods 8 is low,
The ball nut 4 is eccentric due to the tension of the timing belt wound around the pulley 12, and the base portion 3 of the ejector rod 3 is
b may be dragged to one side in the radial direction, and further, the position of the knockout bar 7 fixed to the base portion 3b of the ejector rod 3 may be eccentric and the guide rods 8, 8 may be bent. When the protrusion / retraction operation is repeated a plurality of times by repeating forward / reverse rotation, the guide rods 8, 8 are inadvertently changed by switching the rotation direction of the ball nut 4, that is, by changing the direction of the tension given by the timing belt. Vibration may occur.

In particular, in the conventional ejector mechanism 100 as shown in FIG. 1, most of the tension applied by the timing belt directly acts as energy for causing the guide rods 8 and 8 to bend or vibrate. The tendency is remarkable.

Also in this embodiment shown in FIG. 2, the tension applied by the timing belt causes the guide rods 8 and 8 to be tensioned.
However, in the case of the present embodiment, since the tip end portions of the guide rods 8 and 8 are integrally fixed to each other by the connecting member 16, the guide rods 8 and 8 are not bent. In order to vibrate, the guide rods 8, 8
2 and the connecting member 16, in short, the arrow A,
The portion indicated by A must be distorted. That is,
In the example of FIG. 2 in which the connecting member 16 is attached orthogonally to the guide rods 8 and 8, the angles of the portions indicated by arrows A and A change to angles other than 90 °, or the connecting member 1
Unless the 6 itself bends or expands or contracts, it is difficult for the guide rods 8, 8 to bend or vibrate. As a result, the tension applied by the timing belt and the force that causes the guide rods 8 and 8 to bend or vibrate and the arrows A and A
Will be divided into two kinds of forces, namely, a force that distorts the portion indicated by and a force that bends or expands or contracts the connecting member 16, and as long as the tension given by the timing belt is the same, the connecting member 16 is attached. When the connecting member 16 is attached, the force for bending or vibrating the guide rods 8 is relatively reduced as compared with the case where the connecting member 16 is not attached. That is, the bending and vibration of the guide rods 8, 8 are reduced.

As described above, according to the present embodiment, the guide rods 8 and 8 can be substantially attached only by attaching the connecting member 16 without increasing the diameter of the guide rods 8 and increasing the number of the guide rods 8 and 8. The rigidity can be enhanced. Since the connecting member 16 itself can be easily manufactured by punching with a press, sheet metal working, casting, or the like, it is necessary to enhance rigidity as compared with mounting the large-diameter guide rods 8 and 8 or increasing the number of mounting guide rods 8. The increase in manufacturing cost caused is small. In addition, the loosening of screw portions (for example, bolts 5, 10, 14 etc.) caused by the vibration of the guide rods 8, 8 is also prevented. Further, in the embodiment shown in FIG. 2, the connecting member 16 is simply fastened to the guide rods 8 and 8 together by the bolts 10, and even when the guide rods 8 and 8 are erected by another method, the guide rod 8 Since it is possible to easily strengthen the guide rods 8 and 8 substantially by simply attaching the connecting member 16 to the tip surfaces of the guide rods 8 and 8, the conventional ejector mechanism as shown in FIG. The configuration of this embodiment can also be directly applied to 100.

In the example shown in FIG. 2, two guide rods 8 and 8 are arranged diagonally on the back surface of the moving platen 2 having a rectangular front shape. There are also those in which the guide rods 8, 8, 8, 8 are arranged at the four corners on the back surface of. Also, 2
In the case where the book guide rods 8, 8 are provided, in order to better achieve the effect of preventing the bending and vibration due to the mounting of the connecting member 16, the direction in which the tension applied by the timing belt or the like (the drive shaft of the electric motor is Ball nut 4
It is effective to dispose the electric motor so that the line connecting the centers of the two) is in substantially the same direction as the line connecting the disposing positions of the guide rods 8, 8.

[0022]

The ejector mechanism of the injection molding machine according to the present invention enhances the substantial rigidity of the guide rod by integrally fixing the other end of the guide rod standing on the back surface of the moving platen by the connecting member. Therefore, even when the force from the power transmission means that drives the ejector rod acts in the radial direction of the guide rod, the guide rod does not easily bend or vibrate, and the ejector rod moves straight when it protrudes or retracts. Is guaranteed. In addition, as a result of suppressing vibration, accidents such as inadvertent loosening of the screwing elements of each part of the ejector mechanism are prevented, and the guide rods are effectively attached without increasing the diameter or the number of guide rods. Since relative rigidity can be enhanced, relative cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a side sectional view schematically showing a configuration of a conventional ejector mechanism.

FIG. 2 is a side sectional view schematically showing a configuration of an ejector mechanism of one embodiment to which the present invention is applied.

[Explanation of reference symbols] 1 ejector mechanism 2 moving platen 2a die mounting surface 3 ejector rod 3a ejector rod tip 3b ejector rod base 4 ball nut 4a retainer 5 bolt 6 sleeve 7 knockout bar 8 guide rod 9 long sleeve 9a Large diameter part 10 Long bolt 11 Female screw 12 Pulley 13 Small diameter part of through hole 14 Bolt 15 Staple 16 Connecting member 16a Bolt through hole

Claims (1)

[Claims] 1. A guide rod is provided with one end of a plurality of guide rods standing on the back surface of a moving platen to guide a projecting / retracting motion of the ejector rod, and a force acting from a power transmission means for driving the ejector rod is applied by the guide rod. An ejector mechanism of an injection molding machine, wherein the other end of each ejector rod is integrally fixed by a connecting member in the ejector mechanism of the injection molding machine which is received in the radial direction.