JPH045301Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The invention is applicable to injection compression molding machines, and is particularly applicable to optical heads of compact disc players and lenses of optical equipment such as video cameras. This invention relates to an injection compression molding machine suitable for molding plastic lenses.

(Prior art) Conventional molding machines used to mold plastic lenses as described above employ center injection when performing injection molding.
As disclosed in Publication No. 57-105331, each dividing surface of the spool part, runner part, and gate part is configured to be movable while being in close contact with each other, and re-clamping (compression) is performed by mold clamping of the molding machine. This is done using motion.

By the way, in this type of molding, the volume and pressure of the resin in the cavity decreases as the resin cools, and if the resin is cooled in that state until it is taken out,
A problem has been pointed out that the resin in the cavity cannot be brought into sufficient contact with the surface of the core mold, resulting in a decrease in the shape accuracy of the lens surface.

(Problems to be solved by the invention) However, according to the configuration shown in the above-mentioned publication, the re-clamping process (compression process) is performed by a mold-clamping operation, and the re-clamping operation connects the cavity and the gate part. Due to the cut-off, it is not possible to program the free compression force of the compression process. That is, if the cavity and the gate part are shut off by a slow process, it becomes impossible to eliminate the phenomenon in which the resin in the cavity flows back into the gate part. Additionally, it is possible to control the compression force by controlling the pressure oil in the mold clamping cylinder, but this requires pressure oil to be applied to the large diameter area, resulting in poor response and requiring high precision. There is a problem in that it is unsuitable in cases such as lens molding.

[Structure of the idea]

(Means for Solving the Problems) In order to achieve the above object, the present invention has a movable die plate between a fixed die plate and a clamping cylinder, which is moved by the clamping cylinder, In a molding machine in which a fixed mold and a movable mold are respectively attached to opposing surfaces of the die plate, a piston rod fixed to the surface opposite to the mold mounting surface of the fixed die plate passes through the fixed die plate and molds the fixed die. a first cylinder configured to enter the mold; and a second cylinder fixed to a surface of the movable die plate opposite to the mold mounting surface such that the piston rod penetrates the movable die plate and enters the movable mold. a cylinder, a core body that is fitted into the movable mold and whose one end is in constant contact with the tip of the piston rod of the second cylinder through an elastic body and whose other end forms a cavity; and a core body which is provided in the fixed mold. The present invention is characterized in that it includes a cavity main body, one side of which is in contact with the tip of the piston rod of the first cylinder, and the other end of which constitutes a cavity.

(Function) With the above configuration, the cavity is composed of the core body and the cavity body between the mating surfaces of the mold, and the resin injected into the cavity from the right angle direction is transferred from the runner part by moving the core body. Immediately after separation, the cavity body is pressed by the first cylinder to perform a compression process and compression molding can be performed.

(Embodiments) The present invention will be described below with reference to embodiments shown in the drawings.

In the figure, numeral 1 indicates a clamping cylinder, 2 indicates a fixed die plate, and between the clamping cylinder 1 and the fixed die plate 2 are four tie bars 3, 3...
The movable die plate 5 moves forward and backward integrally with the tie bars 3, 3... as the mold clamping ram 4 of the mold clamping cylinder 1 advances and retreats, using the tie bars 3, 3 as a guide.
is provided.

A fixed die 6 is attached to the die attachment surface of the fixed die plate 2, and a movable die 7 is attached to the die attachment surface of the movable die plate 5, and is movable by the clamping ram 4 of the mold clamping cylinder 1. The fixed mold 6 and the movable mold 7 are brought into contact and separated by moving the die plate 5 back and forth.

A first cylinder 8 functioning as a compression cylinder is fixed to the surface of the fixed die plate 2 opposite to the mold mounting surface, and the piston rod 9 of this cylinder 8 penetrates the fixed die plate 2 and enters the fixed mold 6. arranged to enter.

Further, a cavity 10 is formed at the end of the mold clamping ram 4 on the movable die plate 5 side, and a second cylinder 11 that functions as an extrusion cylinder is located within this cavity 10 and is connected to the movable die plate. The piston rod 12 of the cylinder 11 is fixed to the opposite surface of the plate 5 from the mold mounting surface, and is arranged so as to penetrate the movable die plate 5 and enter the movable mold 7.

A core body 14 configuring one side of the cavity 13 is fitted into the movable mold 7 between opposing surfaces of the molds 6 and 7 so as to be slidable in the axial direction. A cavity main body 15 constituting the other side is housed so as to be movable in the axial direction.

The core body 14 is in constant contact with the tip of the piston rod 12 of the second cylinder 11 by a return coil spring 16 as an elastic body, and the core body 14 is in constant contact with the tip of the piston rod 12 of the second cylinder 11
5 is in contact with the tip of the piston rod 9 of the first cylinder 8.

A portion 15A of the cavity main body 15 is in contact with the movable mold 7 to limit the cavity position,
Further, in another part 15B of the cavity main body 15, a runner extrusion pin 17 is provided with a spring 18 to give it a return behavior.

An injection nozzle 19 is positioned on one side of the mating surfaces of the molds 6 and 7 so as to be movable forward and backward, and is adapted to inject into the mold. In the figure, 20 indicates a runner section.

Next, the operation of the above embodiment will be explained.

To close the molds 6 and 7, apply pressure oil to the left chamber 1A of the mold clamping ram 4 of the mold clamping cylinder 1,
By moving the movable die plate 5 to the right, the mating surfaces of the molds 6 and 7 are closed, and at the same time, pressure oil is applied to the right side chamber 8A of the first cylinder 8 in the drawing. Thereby, the cavity 13 is constituted by the core body 14 with a portion 15A of the cavity body 15 in contact with the movable mold 7. Further, at this time, the runner extrusion pin 17 does not protrude from the parting surface.

Next, the nozzle 19 moves forward and comes into contact with the mold parting surface, and the molten resin is injected.The injected resin is press-fitted into the cavity 13 through the runner section 20, and when the injection is completed, the metering operation is started. At the same time, in the diagram of the second cylinder 11, the left side chamber 11A
Pressure oil is applied to the piston rod 1.
2 advances to the right in the figure against the spring 16,
Since the molten resin in the cavity 13 is pushed, the piston rod 9 of the first cylinder 8 pushes against the cavity body 1.
5 to the right in the figure. At this time, the relationship between the pressing force by the second cylinder 11 and the compression force is "pressing force>compression force". By this pressing operation, the resin of the cavity 13 and runner section 20 is cut and separated. Note that when the metering operation is completed, the nozzle 19 retreats and enters standby.

Next, the oil pressure (left side chamber) of the second cylinder 11 is blocked, and in this state, pressure oil is applied to the right side chamber 8A of the first cylinder 8 to perform a compression operation. After cooling is completed, the movable die plate 5 moves backward, and the piston rod 9 of the first cylinder 8 moves to the left to discharge the product molded in the cavity 13. is discharged by

Note that an electromagnetic flow rate proportional valve (pressure valve) may be provided in the compression side hydraulic circuit of the first cylinder 8 that performs the compression operation to control the pressure or flow rate based on time. Further, the configuration of each part is not limited to the illustrated embodiment, and design changes may be made arbitrarily without departing from the technical idea of the present invention.

[Effect of idea]

As explained above, the injection compression molding machine according to the present invention has a movable die plate that is moved by the mold clamping cylinder between the fixed die plate and the mold clamping cylinder, and the fixed mold is mounted on the opposing surface of these die plates. and a movable mold, the first piston rod being fixed to a surface opposite to the mold mounting surface of the fixed die plate so that the piston rod penetrates the fixed die plate and enters the fixed mold. a second cylinder fixed to a surface of the movable die plate opposite to the mold mounting surface so that a piston rod penetrates the movable die plate and enters the movable mold; a core body which is inserted and one end of which is in constant contact with the tip of the piston rod of the second cylinder through an elastic body and which constitutes a cavity at the other end; Since the structure has a cavity body whose other end is in contact with the cavity and which constitutes the cavity, the compression process can be started immediately after injecting the molten resin into the cavity without holding a gate seal, improving work efficiency. It is possible to significantly improve the compression force during compression.
Since this can be done by controlling the oil pressure of the cylinder, the injection compression molding machine can be easily and precisely controlled, making it possible to obtain an injection compression molding machine that is ideal for molding optical lenses that require precision.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. 1... Mold clamping cylinder, 2... Fixed die plate, 3... Tie bar, 4... Mold clamping ram, 5... Movable die plate, 6... Fixed mold, 7... Movable mold, 8... 1st cylinder, 9... Piston rod, 11... Second cylinder, 12... Piston rod, 13... Cavity, 14... Core body,
15... Cavity body, 17... Runner extrusion pin, 19... Injection nozzle, 20... Runner portion.

Claims (1)

[Scope of utility model registration request] A molding machine having a movable die plate moved by the clamping cylinder between a fixed die plate and a clamping cylinder, and a fixed mold and a movable mold each mounted on opposing surfaces of these die plates. A first cylinder fixed to a surface opposite to a mold mounting surface of a fixed die plate so that a piston rod penetrates the fixed die plate and enters the fixed mold, and a mold mounting surface of the movable die plate. A second cylinder is fixed to the opposite surface so that the piston rod passes through the movable die plate and enters the movable mold; a core body that is always in contact with the tip and that forms a cavity at the other end; and a cavity that is provided within the stationary mold and whose one side is in contact with the tip of the piston rod of the first cylinder and whose other end forms the cavity. An injection compression molding machine comprising: a main body;