JPH09174622A - Ejector mechanism doubling as gate cut mechanism for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a mechanism compact and prevent a molding from being smeared with grease by making a gate cut mechanism drive a ball screw member with an electric motor and move a gate cut plate and a drive-side gate cut pin, and making an ejector mechanism drive a drive-side ejector pin with a pneumatic cylinder device. SOLUTION: A support member 14 is fixed to a movable platen 3b through a plurality of guide pins 43. When a gate cut mechanism 10 is to be operated, each pulley 16 is driven by an electric motor 20 fixed to the support member 14 through a drive pulley 21 and a belt 22 in a wrapping drive device 25. Thus, a gate cut plate 18 and further a drive-side gate cut pin 12 arranged at the movable platen 3b are made to proceed through each ball screw member 15 and each nut member 17. Next, an ejector mechanism 30 is operated. That is, when pressure air is supplied to a pneumatic cylinder device 24, the drive-side ejector pin 32 extrudes a driven-side ejector pin by moving in the drive-side gate cut pin 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate cutting mechanism and an ejector mechanism for injection molding.

[0002]

2. Description of the Related Art In a conventional injection molding machine, a molten molding material such as resin is plasticized and melted by a screw in a cylinder barrel, and then the cylinder barrel is advanced.
The nozzle at the tip of the cylinder barrel is brought into close contact with a fixed mold for injection molding, and the molten molding material is injected and filled into the cavity in the mold through the sprue, runner and gate. An injection molding machine of this type is known that includes an ejector mechanism and a gate cut mechanism. This ejector mechanism is provided in a mold for ejecting a molded product like a general ejector mechanism, but ejector pins are driven by hydraulic means. Also, this gate cut mechanism is a mechanism that opens and closes the gate like a general gate cut mechanism, but the gate cut pin is driven by a hydraulic cylinder device to match the ejector mechanism and the drive source type. There is. The gate cut pin and the ejector pin are attached to the movable plate.

That is, in a conventional injection molding machine having both an ejector mechanism and a gate cut mechanism, a gate cut hydraulic cylinder device and an ejector hydraulic cylinder device each driven by a hydraulic power source are provided. Built-in, gate cut pin and ejector pin were driven separately. Therefore, in addition to the hydraulic pump as a hydraulic source, a plurality of hydraulic valves, piping, etc. are provided.

As described above, since the injection molding machine having the conventional ejector mechanism and gate cut mechanism is of the hydraulic type, it is unavoidable that oil leakage occurs, and scattered operating oil adheres to the molded product. There was a technical problem of doing. Especially when molding optical parts and food-related molded products, the adhesion of hydraulic oil reduces the commercial value,
It becomes a problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional technical problem.
It is as follows. The invention of claim 1 is an injection molding gate cut mechanism / ejector mechanism in which the gate cut mechanism 10 and the ejector mechanism 30 operate independently of each other.
The gate cut mechanism 10 includes a drive side gate cut pin 12 movably arranged on the movable platen 3b, a support member 14 fixed to the movable platen 3b, and a gate cut plate 18 fixed to the drive side gate cut pin 12. Nut member 17 fixed to the gate cut plate 18 and nut member 17
Has a ball screw member 15 with which the screw portion 15a is engaged,
A ball screw mechanism in which the ball screw member 15 is rotatably supported by the support member 14 and is immovable in the central axis direction;
An electric motor 20 fixed to the support member 14 and a winding transmission device 25 that is wound between the motor shaft 20a of the electric motor 20 and the ball screw member 15 and drives the ball screw member 15 to rotate forward and backward. The ejector mechanism 30 includes a drive-side ejector pin 32 that is movably arranged in the through hole of the drive-side gate cut pin 12, and a pneumatic cylinder device that is fixed to the support member 14 and drives the drive-side ejector pin 32. 24 is a gate cut mechanism and an ejector mechanism for injection molding. The invention according to claim 2 is the injection-cutting gate-cut mechanism and ejector mechanism according to claim 1, wherein a plurality of ball screw mechanisms are arranged at equal distances from the drive-side gate-cut pin 12.

[0006]

According to the invention of claim 1, the gate cut mechanism 1
0 and the ejector mechanism 30 operate independently and independently as follows. The gate cut mechanism 10 includes a support member 14
If the electric motor 20 fixed to the
The ball screw member 15 is rotationally driven in the forward or reverse direction by the winding transmission device 25 wound between the motor shaft 20a of 0 and the ball screw member 15. The ball screw member 15 is rotatably supported by the support member 14 and is immovable in the central axis direction. Therefore, the screw portion 15 a of the ball screw member 15 is provided.
The nut member 17 engaged with the gate cut plate 1
8 and the gate cut pin 12 on the driving side.
Since the drive-side gate cut pin 12 moves within the movable platen 3b, the movement of the drive-side gate cut pin 12 causes
The gate can be cut off. When the ball screw member 15 is rotationally driven in the opposite direction by the electric motor 20, the gate is opened.

The ejector mechanism 30 drives the ejector pin 32 on the drive side when the pneumatic cylinder device 24 is operated to project.
Are driven in the through hole of the drive-side gate cut pin 12.
By driving the ejector pin 32 on the driving side, the molded product can be ejected from the cavity. When the pneumatic cylinder device 24 is retracted, the drive side ejector pin 3
2 can be returned. As described above, since the operation of the gate cut mechanism 10 and the ejector mechanism 30 is obtained by the electric motor 20 and the pneumatic cylinder device 24,
There is no oil leakage and it is possible to prevent oil from splashing onto the molded product, and by combining these two types of drive systems, it is possible to simplify the structure and reduce costs.

According to the second aspect of the present invention, since the gate cut plate 18 is driven at a plurality of positions equidistant from the drive side gate cut pin 12, the operation of the gate cut mechanism 10 can be stably obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a gate cutting mechanism and ejector mechanism for injection molding according to an embodiment of the present invention. In the figure, reference numeral 1 indicates a mold for injection molding, and the mold 1 comprises a fixed mold 2a and a movable mold 3a facing the fixed mold 2a. The fixed mold 2a defines a sprue 9 extending on the central axis of the fixed mold 2a, and a sprue bush 2c slidably fitted into the fixed mold 2a.
The fixed mold 2a is fixed to the fixed platen 2b.
On the other hand, the movable mold 3a is clamped with the fixed mold 2a to define a plurality of cavities 7.
a is fixed to the movable platen 3b, and the movable platen 3b is driven back and forth by a mold clamping device (not shown) such as a toggle type or a direct pressure type. The sprue 9 and each cavity 7 can be connected to each other via a runner 5 and a gate 6 which are formed between a driven gate cut pin 13 and a sprue bush 2c, which will be described later.

The movable plate 3b is equipped with a gate cut mechanism 10 and an ejector mechanism 30. The gate cut mechanism 10 includes a gate cut pin 11 as shown in FIGS. 1 and 2. The gate cut pin 11 includes a drive-side gate cut pin 12 and a driven-side gate cut pin 13 which are coaxially arranged. Driven gate cut pin 13
Is housed in the movable mold 3a so as to be movable in the direction of the central axis in the form of a cylinder, and is constantly urged to return by the first return spring 40 that is arranged between the movable mold 3a and the movable mold 3a in a compressed state. ing. The driven-side gate cut pin 13 is in a non-actuated state in which it is returned by the first return spring 40, the projection 13a contacts the step surface 3c of the movable mold 3a, and the runner is provided between the sprue bush 2c and the front end surface. It is possible to partition the gate 5 and partition the gate 6 connected to the inner end of each cavity 7 in an open state. The drive-side gate cut pin 12 has a cylindrical shape, and the rear end portion is screwed to the gate cut plate 18,
The front end surface faces the rear end surface of the driven gate cut pin 13.

The gate cut plate 18 is driven by a plurality of ball screw mechanisms arranged at equal distances from the drive side gate cut pin 12. That is, a pair of nut members 17 are fixed to the gate cut plate 18, and the screw portions 15a at the tip of the ball screw member 15 are engaged with the respective nut members 17 via balls (not shown).
Each ball screw member 15 has an intermediate portion of a shaft portion supported rotatably and immovably in the central axis direction via a bearing 44, and a pulley 16 is attached to the rear end shaft portion. It is fixed. The bracket portion 14a of the support member 14 includes an electric motor 2 which is a servo motor.
0 is fixed, and the drive pulley 21 is fixed to the motor shaft 20a. The belt 22 is wound around the drive pulley 21 and each pulley 16 to form a winding transmission device 25. In this winding transmission device 25, since it is necessary to drive the ball screw members 15 synchronously, it is desirable that the belt 22 be a toothed belt.

On the other hand, the support member 14 is disposed behind the gate cut plate 18 and is fixed to the movable plate 3b via a plurality of guide pins 43 screwed to the movable plate 3b. Then, the drive pulley 21 is driven by the electric motor 20.
By rotating the pulleys 16 in the forward and reverse directions, the ball screw members 15 supported by the bearings 44 are driven.
Is rotated, the nut member 17 and the gate cut plate 18, and thus the drive side gate cut pin 12 can be driven forward and backward in the central axis direction. The gate cut plate 18 is slidably fitted on the middle portion of the guide pin 43 with a bush 45 interposed therebetween, and is stably moved forward and backward while being guided by the guide pin 43.

The ejector mechanism 30 includes an ejector pin 31 as shown in FIGS. Ejector pin 3
Reference numeral 1 includes a drive-side ejector pin 32 and a driven-side ejector pin 33 which are coaxially arranged. The drive-side ejector pin 32 is rod-shaped, is movably and concentrically inserted into the through hole of the drive-side gate cut pin 12 having a cylindrical shape, and its rear end is fixed to the piston rod 24 a of the pneumatic cylinder device 24. ing. The driven ejector pin 33 has a rod shape, and has a pin main body 33a whose rear end face faces the front end face of the drive side ejector pin 32, and two branch pins 33b branched from an intermediate portion of the pin main body 33a. Pin body 33a
Is slidably and concentrically supported in the driven-side gate cut pin 13, and is normally urged to return by a second return spring 41 that is compressed between the driven-side gate cut pin 13 and the driven-side gate cut pin 13. . Each branch pin 33b has an L shape, and the rear end portion is received in the radial cut groove 13b at the rear end portion of the driven-side gate cut pin 13 to allow relative movement in the central axis direction, and the tip end. The side of the second return spring 4 is slidably supported in the movable mold 3a in the central axis direction.
In the state of returning to the rear by 1, the front end face defines the cavities 7, respectively.

The pneumatic cylinder device 24 includes a support member 14
The drive-side ejector pin 32 is driven forward and backward by supplying and discharging pressurized air from an air source (not shown) to a pair of pressure chambers 24c that are fixedly installed on both sides of the piston 24b. Although the pneumatic cylinder device 24 is shown as a double-acting type in FIG. 1, it can also be configured as a single-acting type by urging the return of the piston 24b by a spring (not shown). .

When both the gate cut mechanism 10 and the ejector mechanism 30 are driven by the electric motor 20 and the ball screw mechanism, the structure becomes complicated, which is disadvantageous in terms of accommodation space and cost. On the other hand, when both the gate cut mechanism 10 and the ejector mechanism 30 are driven by the pneumatic cylinder device 24, it is difficult to control the operating speed and pressure (torque) of the gate cut with high accuracy, and the operation (disconnection) is performed. ), The quality of the molded product is likely to deteriorate. Therefore, the gate cut mechanism 10
As a drive source of the gate cut pin 11 of the electric motor 2
0 and a ball screw mechanism are used to ensure high precision control of the gate cut operating speed and pressure (torque), and the pneumatic cylinder device 24 is used as a drive source for the ejector pin 31 of the ejector mechanism 30. To simplify the structure.

Next, the operation will be described. In injection molding, well-known mold closing process, mold clamping process, injection unit advancing process, injection process, measuring process, injection unit retracting process,
The mold opening process, the ejecting process, and the intermediate process are sequentially performed. First, a mold closing process and a mold clamping process are performed, and as shown in FIG. 2, the movable mold 3a is brought into close contact with the fixed mold 2a, and the injection unit advance process is performed to bring the nozzle of the injection molding machine (not shown) into close contact. After closely contacting the portion 2d, the injection process is started. At that time, the sprue bush 2c is pushed in, the flange-shaped portion 2e contacts the step surface 2f of the fixed mold 2a, and the driven-side gate cut pin 13 is retracted by the elastic force of the first return spring 40. Then, the gate 6 is opened, and the driven ejector pin 33 retreats by the elastic force of the second return spring 41 to partition the cavity 7.

Next, when the molten molding material is injected from the nozzle of the injection molding machine, the molten molding material flows into the cavity 7 through the sprue 9, the runner 5 and the gate 6. When the molten molding material fills the cavity 7, the process proceeds to the injection unit retracting step to separate the nozzle of the injection molding machine from the contact portion 2d and operate the gate cut mechanism 10. That is, the drive pulley 21 is driven by the electric motor 20.
Is driven, each pulley 16 is rotationally driven in one direction via the belt 22. When each pulley 16 rotates in one direction, each ball screw member 15 rotates, so that each nut member 17 and the gate cut plate 18, and thus the drive side gate cut pin 12 can be advanced in the central axis direction. As a result, the driven-side gate cut pin 13 is pushed out against the elastic force of the first return spring 40, and the gate 6 is driven by the driven-side gate cut pin 13 as shown in FIG.
Is cut by the tip of the. At that time, the sprue bush 2c is slightly pushed back.

When the gate 6 is cut, the mold opening process is performed, the movable mold 3a is retracted, and the ejecting process is operated to operate the ejector mechanism 30. That is, when pressure air from an air source (not shown) is supplied to the pressure chamber 24c on the rear side of the pneumatic cylinder device 24, the drive side ejector pin 32 projects together with the piston rod 24a and moves inside the drive side gate cut pin 12. While pushing the ejector pin 33 on the driven side. Driven ejector pin 33
As shown in FIG. 4, each branch pin 33b projects the solidified product A in each cavity 7, and at the same time, the pin body 33a projects the solidified product B on the sprue 9. that time,
The second return spring 41 is compressed and deformed. Thus, the gate cutting mechanism 10 and the ejector mechanism 30 operate independently, so that the gate 6 is cut and the molded product A is ejected individually.

By the way, in the above embodiment, the gate cut pin 11 is divided into the drive side gate cut pin 12 and the driven side gate cut pin 13, and the driven side gate cut pin 13 is returned to the first return spring. It was urged by 40. However, drive side gate cut pin 12
Is precisely reciprocated by an electric motor 20, a winding transmission device 25, and a ball screw mechanism. Therefore, the gate cut pin 11 is formed in the same body, and the first return spring 40
May be omitted.

[0020]

As will be understood from the above description,
According to the gate molding mechanism and the ejector mechanism for injection molding of the present invention, both the gate cutting mechanism and the ejector mechanism are concentrically provided so as to operate individually, and the contamination of the molded product due to oil leakage becomes a problem. In the injection molding machine, the configuration of the electric motor and pneumatic cylinder device,
It is possible to completely prevent a decrease in commercial value due to oil stains on a molded product. In addition, by combining the gate cut mechanism equipped with the electric motor and ball screw mechanism and the ejector mechanism equipped with the pneumatic cylinder device, it is possible to reduce the storage space for the gate cut mechanism and the ejector mechanism while ensuring proper operation of both mechanisms. This allows the injection molding gate cut mechanism and ejector mechanism to have a small overall size.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a driving side of an injection molding gate cut mechanism / ejector mechanism according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the driven side of the injection-molding gate-cut mechanism / ejector mechanism as well.

FIG. 3 is an explanatory view of the same operation on the driven side.

FIG. 4 is an explanatory view of the same operation on the driven side.

[Explanation of symbols]

1: mold, 2a: fixed mold, 3a: movable mold, 10: gate cut mechanism, 12: drive side gate cut pin, 1
3: Driven side gate cut pin, 14: Support member, 15:
Ball screw member, 15a: screw part, 17: nut member,
18: Gate cut plate, 20: Electric motor, 20
a: motor shaft, 24: pneumatic cylinder device, 24a: piston rod, 25: winding transmission device, 30: ejector mechanism, 32: drive side ejector pin, 33: driven side ejector pin.

Claims (2)

[Claims] 1. A gate cutting mechanism and an ejector mechanism for injection molding, wherein the gate cutting mechanism (10) and the ejector mechanism (30) operate independently of each other, wherein the gate cutting mechanism (10) is a movable platen (3b). A drive side gate cut pin (12) movably arranged on the drive side, a support member (14) fixed to the movable plate (3b), and a gate cut plate (18) fixed to the drive side gate cut pin (12). ,
A nut member (17) fixed to the gate cut plate (18) and a ball screw member (15) with which the screw portion (15a) engages with the nut member (17), and the ball screw member (15) is a support member. A ball screw mechanism rotatably supported by (14) so as not to move in the direction of the central axis, an electric motor (20) fixed to the support member (14), and a motor shaft (20a) of the electric motor (20). And a ball screw member (15) wound around the ball screw member (15).
And a winding transmission device (25) for rotationally driving the
The ejector mechanism (30) is fixed to the drive side ejector pin (32) movably arranged in the through hole of the drive side gate cut pin (12) and the support member (14), and the drive side ejector pin (32) is provided. 32) A pneumatic cylinder device (24) for driving the injection molding gate cutting mechanism and ejector mechanism for injection molding. 2. The injection-molding gate-cut mechanism and ejector mechanism according to claim 1, wherein a plurality of ball-screw mechanisms are arranged at an equal distance from the drive-side gate-cut pin (12).