JPH0427014B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ejecting device used in an injection molding machine to peel and eject a molded product from a mold.

[Prior Art] Fig. 10 shows the basic structure of a general toggle type injection molding machine, in which a fixed plate 1 and an end plate 2 are erected on a pedestal 3 facing each other. A movable plate 5 is supported by a tie bar 4 horizontally installed between a fixed plate 1 and an end plate 2 so as to be movable back and forth. A stationary die 6 and a movable die 7 are fixedly installed on opposing surfaces of the stationary platen 1 and the movable platen 5, and a mold M is constituted by the two. A toggle mechanism 8 is disposed between the end plate 2 and the movable plate 5, and when this toggle mechanism 8 is operated by a hydraulic cylinder 9 disposed at the center of the end plate 2, the movable plate 5 is moved. It moves to close and open the mold. Behind the stationary platen 1 is an injection tube (not shown) that holds the molten plastic raw material, and an injection tube (not shown) that holds the molten plastic raw material is installed inside the injection tube to transfer the plastic raw material from the injection tube to the nozzle 1.
A screw (not shown) is provided for injecting into the mold through a series of operations, namely:
A series of operating operations such as the closing operation of the mold M, the clamping operation during injection, and the opening operation of the mold M are performed continuously while controlling the moving speed, and the pressure applied to the screw is controlled to improve the speed during solidification. The resin pressure inside the mold is kept at an appropriate value to obtain a precise molded product. Then, when the mold is opened, the molded product moves while remaining attached to the movable mold 7, and is ejected and removed by a protruding mechanism attached to the movable platen 5. As such a protrusion mechanism, a mechanism using a hydraulic cylinder as a drive mechanism is normally used, and this is attached to the rear of the movable platen 5.

By the way, in recent years, in order to meet the demand for products that require precision molding such as compact disks, or products that require thick and precise molding, mold volume is contracted after injection and the mold is further clamped.
There is a method (compression molding method) that performs stronger compression. This compression molding method involves filling the mold with resin without fully extending the toggle, and then extending the toggle to clamp the mold. There is a low-links method in which the cavity is made weaker, and after filling with resin, the expanded cavity is further compressed by the resin injection pressure. In all of these compression methods, the entire movable mold is moved relative to the fixed mold (full surface compression method), but for example, if the thickness of the molded product is uneven, the compression ratio will be lower than the thickness of the thin part. , and sufficient compression cannot be achieved. Therefore, there is a micro molding method in which only the core portion constituting the cavity of the mold is partially movable, and a movable platen is provided with a hydraulic device (hydraulic cylinder) that compresses only the core portion.

[Problems to be Solved by the Invention] However, in the conventional technology as described above, the hydraulic cylinder has a shape that protrudes from the rear of the movable platen, so a space is required to incorporate it, and the device itself is There were problems such as the large size and the narrow degree of freedom in design due to the conflict with the toggle mechanism described above. In particular, in the micromolder type injection molding machine as described above, it is necessary to provide an ejection hydraulic cylinder in series behind the compression hydraulic cylinder, which further exacerbates the above-mentioned problems.

[Means for Solving the Problems] In order to solve the above problems, the present invention has a fixed plate, a movable plate provided to be movable back and forth with respect to the fixed plate, and a piston. A compression hydraulic cylinder configured inside the movable plate; a mold mounting plate located on the front side of the movable plate and detachable from the piston rod of the piston and the movable plate; and the mold mounting plate. A core rod is inserted into the insertion hole and attached to the piston, and the piston of the compression hydraulic cylinder is equipped with an ejection hydraulic cylinder for operating an ejection pin penetrating the core rod.

[Function] In the ejection device of the injection molding machine configured as described above, it is possible to easily switch between core compression and full-scale compression, and the ejection hydraulic cylinder is built into the compression hydraulic cylinder. ,
The ejecting hydraulic cylinder does not protrude to the rear of the movable platen, making the entire device compact, reducing the total weight of the movable platen, and speeding up the operation.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. The basic structure of the injection molding machine itself is the same as that shown in FIG.

In FIG. 1, reference numeral 11 is a movable platen (corresponding to the movable platen 5 in Fig. 10), and a fixed platen 1 (the 10th
The tie bar 12 (4 in FIG. 10) is inserted between the end plate 2 and the fixed platen 1 and is movably provided. The movable platen 11 is formed in the shape of a thick plate, and a toggle mechanism as described above is interposed between the movable platen 11 and the end plate to drive the movable platen 11. A compression cylinder 1 is installed inside the movable platen 11.
3 are made up. That is, in the center of the movable platen 11, there is a through hole 14 that opens to the front and rear surfaces (hereinafter, the side facing the mold is referred to as the front surface, and the end plate side is referred to as the rear surface), and the diameter increases as it goes from the rear side to the front side. It is formed with a first step 15 and a second step 16. An annular holding member 17 is fixed to this second step 16 with a bolt 18, and as a result, a diameter-reducing step is formed in the through hole 14 from the rear surface to the front surface, and the portion sandwiched between these steps is the hydraulic chamber 19.
It's getting old. The through hole 14 has a small diameter portion 20, a piston 21,
A sliding member 23 integrally formed with a piston rod 22 is fitted, and a core rod 24 is fixed to the front surface of the piston rod 22 with a bolt 25. Oil passages 26 and 27 leading to an external oil pressure source are opened before and after the oil pressure chamber 19, and by supplying oil pressure to these oil passages 26 and 27, the piston 21 is moved back and forth. There is.

A cylindrical first stopper 28 that restricts the retreating position of the sliding member 23 is provided in a small diameter portion on the rear side of the through hole 14, and a fine thread is formed on the inner surface of the through hole 14 and the outer surface of the first stopper 28. 29, and is attached to the movable board 11 so that its position can be adjusted. The rear end of the first stopper 28 is set to protrude from the through hole 14 , and a key 31 extending back and forth is attached to this protrusion 30 . A sprocket 32 having an inner groove that fits into the key 31 is attached with a support plate 33 preventing it from moving back and forth. This sprocket 32 is connected to a drive shaft (not shown) by a chain. Above piston 2
1 is set to have a thickness shorter than the length of the hydraulic chamber 19, so that the piston 21 can move by the difference. The value of this difference can be changed by replacing the holding member 17. A fine thread 34 is formed on the outer peripheral surface of the small diameter portion 20, and a positioning nut (second stopper) 35 for regulating the forward limit of the sliding member 23 is screwed onto this thread. A slit 36 is formed in this positioning nut 35, and after rotating the nut, the slit 36 is compressed by a bolt 37 to tighten the nut 3.
5 is elastically deformed to prevent its movement.

Inside the sliding member 23, a protrusion cylinder 39 is provided on the rear end side, and a housing chamber 41 for accommodating the protrusion plate 40 is formed on the front end side with an open front. The ejection cylinder 39 has a hydraulic chamber 42 formed to extend back and forth, and
The hydraulic chamber 42 has oil passages 44 (the rear end side not shown) open at the front and rear ends of the hydraulic chamber 42, respectively. The second piston 43 is connected to the protrusion plate 40 via a piston rod 46, and the protrusion plate 40 has five protrusion pins 47 disposed in the center and on the circumference. is inserted into a pin hole 48 formed in the core rod 24. A ring-shaped bush 49 is attached to the opening of the pin hole 48, so that the ejecting pin 47 can be precisely aligned. A dog 38 is fixed to the second piston 43 , and the dog 38 penetrates the rear wall of the hydraulic chamber 42 and protrudes toward the rear side of the movable plate 11 .
A limit switch (not shown) appropriately installed in 1.
It's starting to work. Note that 45 is an oil passage that supplies lubricating oil around the dog 38.

A mold mounting board 51 is provided on the front side of the movable board 11.
is slidably supported by the diver 12. This mold mounting plate 51 has an insertion hole 52 formed in the center with a smaller diameter than the piston rod 22 and a slightly larger diameter than the core rod 24, and an annular hole 52 with an outer diameter approximately equal to that of the piston rod 22 is formed around the rear opening. A step 53 is formed, and a spacer ring 54 is removably attached thereto. A bolt hole 56 is formed in the mold mounting plate 51 and the piston rod 22 for a bolt 55 that fixes the two through the step 53.
Further, bolt holes 58 for bolts 57 for fixing the mold mounting plate 51 and the movable plate 11 are formed in the mold mounting plate 51 and the movable plate 11.

Next, the operation of the ejection device of the injection molding machine configured as described above will be described.

First, a mounting method for full-surface compression will be explained. In the case of full-scale compression, as shown in the upper half of FIG. At the same time, the bolts 57 for connecting the mold mounting board 51 and the movable board 11 are removed.

Next, a first stopper 28 that determines the relative backward and forward limits of the sliding member 23 with respect to the movable platen 11;
Adjust the second stopper 35. That is, when the drive shaft is driven to rotate the sprocket 32 via the chain, the rotation is stopped by the first stopper 2 due to the engagement of the inner groove of the sprocket 32 with the key 31.
8 and is moved in the front-back direction by a fine thread 29. As a result, the first stopper 28 projects to the inner surface of the hydraulic chamber 19 and pushes the piston 21.
As a result, the mold mounting plate 51 is also pushed by this amount of protrusion, so that a gap is created between it and the movable plate 11 (see FIG. 3). To adjust the second stopper 35, rotate the positioning nut 35 and tighten the bolt 3.
This is done by tightening 7. The space between the first stopper 28 and the second stopper 35 is the space for the piston 21 to move. The movable mold 7 is fixed to the mounting surface of the mold mounting board 51 using fixing bolts or the like.

Hereinafter, the entire surface compression injection molding process will be explained with reference to FIGS. 3 to 5. The toggle mechanism is activated to move the movable plate 11 forward to form a cavity between the movable mold 7 and the fixed mold 6 (mold clamping process, see FIG. 3). Here, there is a compression margin between the molds 6 and 7. Next, resin is injected into the cavity from the nozzle 10 of the fixed mold 6, and at an appropriate timing after or during injection, the compression cylinder 13 is operated to move the mold mounting plate 51 and perform compression ( compression process, see Figure 4). In the compression process, the core rod 24 and the mold mounting plate 51
move forward together, pressure is applied uniformly to the entire surface of the mold M, and the second stopper 35 comes into contact with the first stopper 28 and stops. By adjusting the position of the second stopper 35, the final thickness of the molded product can be precisely set. After the resin has solidified, the toggle mechanism is activated to move the movable plate 11 backward, and the product reaches the ejection position with the product attached to the movable mold 7 (mold opening process). Here, the ejecting cylinder 39 is actuated, the ejecting plate 40 moves forward, the ejecting pin 47 protrudes from the core rod 24, the ejector pin 50 provided on the movable die 7 is ejected, and the product is ejected (ejecting process, Fig. 5). reference). After this, both the ejection cylinder 39 and the compression cylinder 13 are returned to their original positions, and the mold clamping process is started again.

Next, a mounting method for performing core compression will be explained with reference to the lower half of FIG. Remove the bolts 55 that connect the mold mounting board 51 and the piston rod 22, remove the spacer ring 54, and insert the bolts 57 into the bolt holes 58 to attach the mold mounting board 5.
1 is fixed to the movable board 11. In this case, bolt 5
5 and 57 are exposed on the front surface of the mold mounting board 51, and can be easily attached and detached. Furthermore, the mold mounting board 51 is supported by tie bars 12, and the movable board 11
Since it is movable by a toggle mechanism, it is easy to open both. As shown in FIG. 6, the movable mold 7a is for core compression, and the core mold 7a is for core compression.
b is fixed to the core rod 24. stoppa 28,
The adjustment method for No. 35 is the same as for full-surface compression, and the adjustment method for No. 6
The steps are performed in the order shown in FIGS. In this case, the mold mounting plate 51 and the core rod 24 are separated, so when the first stopper 28 is moved forward, the piston rod 22 protrudes into the annular step 53, and the core rod 24 protrudes from the mold mounting plate 51. The core mold 7b moves forward, and the second stopper 35 restricts the forward position of the core rod 24 and the core mold 7b.

The injection molding process for core compression will be explained below with reference to FIGS. 7 to 9. The mold clamping process is the same as the full-surface compression, but there is no need for a compression margin between the molds 6 and 7a (see FIG. 7). Next, injection is performed, and the compression cylinder 13 is operated to perform a compression process. In this case, only the core mold 7b is the mold 7
Since the cavity is compressed by being moved relative to a, even if the cavity is thick only at the center and thin at the periphery, as shown in the example, sufficient compression can be performed locally. Both stoppers 28, 35
As in the case of full-surface compression, the cavity before and after compression can be set precisely.
The mold opening and ejection steps are the same as described above.

In the ejecting device as described above, since the ejecting hydraulic cylinder 39 is installed inside the piston 21 of the compression hydraulic cylinder 13, the piston rod 46 can be relatively short, and therefore even a small diameter rod can be bent sufficiently. Can withstand stress. Also, for the same reason, the ejection hydraulic cylinder 3
Since the weight of the members driven by 9 can be reduced, the moment of inertia of these members is small,
The time required for loading and unloading these items can be shortened, and molding efficiency can be increased. Also, a bush 49 attached to the opening of the pin hole 48
As a result, the ejector pin 47 is precisely centered, ejecting is performed accurately, and uneven loads are prevented from being applied to the ejector pin 47, the ejector plate 40, and even the piston rod 46.

In addition, in this embodiment, the mold mounting board 51
When attached to the working end (piston rod) 22, the compression device compresses the mold mounting plate 51 to perform full compression, and when the connection is removed, core compression can be performed by pushing only the core part of the mold. Therefore, if the shape of the molded product is relatively simple and only requires compression on the entire surface, it is possible to mass-produce multiple products in one process by arranging cavities over the entire surface of the mold, and it is also possible to mass-produce molded products with a thick wall only in the center. For complex shapes such as , core compression can be used to obtain sufficient compression, and can be used depending on the purpose. Further, the insertion hole 52 of the mold mounting plate 51 is made smaller in diameter than the outer diameter of the working end 22, and an annular step 53 larger than the outer diameter of the working end 22 is formed at the peripheral edge of the insertion hole 52 on the working end 22 side. By sandwiching a spacer 54 between the mold mounting plate 51 and the operating end 22 at the step 53, and fixing it with bolts 55,
The mold mounting plate 51 and the working end 22 can be easily and firmly fixed, reducing work effort and improving efficiency, and also eliminates looseness between each member to obtain molded products of good quality. It has the advantage that it is easy to switch between full-surface compression and core compression.

[Effect of the invention] As detailed above, the present invention includes a fixed platen,
A movable plate is provided to be movable back and forth with respect to the fixed plate, a compression hydraulic cylinder having a piston and configured inside the movable plate, and a piston rod of the piston located in front of the movable plate and a piston rod for the piston and the movable cylinder. The piston of the compression hydraulic cylinder is equipped with a mold mounting board that can be individually attached to and removed from the board, and a core rod that is inserted into an insertion hole of the mold mounting board and attached to the piston. The ejection hydraulic cylinder that operates the ejection pin that passes through the is built-in, making it easy to switch between core compression and full-scale compression. There is no protrusion, and the distance between the stationary plate and end plate of the injection molding machine can be shortened, making the entire machine compact, and the total weight of the movable plate is reduced, speeding up the operation and molding. Efficiency can be increased. Similarly, in ejecting hydraulic cylinders, the piston rod is short, so the bending load is small, so the piston rod can be made thinner, the total weight of the ejecting member can be reduced, and molding efficiency can be improved by speeding up the operation. It has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts of the ejecting device of an injection molding machine according to an embodiment of the present invention, Figs. 2 to 9 are schematic diagrams showing its operation, and Fig. 10 is a general toggle type injection molding machine. 1 is a schematic diagram showing the basic structure of the . 11...Moving plate, 13...Compression cylinder, 2
1... Piston, 28... First stopper, 35...
...Second stoppa.

Claims (1)

[Claims] 1. A fixed platen, a movable platen that is provided to be movable back and forth with respect to the fixed platen, a compression hydraulic cylinder having a piston and configured inside the movable platen, and a hydraulic cylinder provided with the piston in front of the movable platen. A piston rod of the compression hydraulic cylinder, a mold mounting plate that is individually removable from the movable plate, and a core rod that is inserted into an insertion hole of the mold mounting plate and attached to the piston. An ejecting device for an injection molding machine, wherein the ejecting device includes an ejecting hydraulic cylinder that operates an ejecting pin that passes through the core rod.