JPH0617042B2 - Injection molding machine compression device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a compression device for performing compression molding in an injection molding machine.

[Prior Art] FIG. 10 shows a basic structure of a general toggle type injection molding machine, in which a fixed platen 1 and an end plate 2 are erected on a pedestal 3 so as to face each other. A movable platen 5 is reciprocally supported by a tie bar 4 horizontally installed between the fixed platen 1 and the end plate 2. A fixed mold 6 and a movable mold 7 are fixedly provided on the surfaces of the fixed plate 1 and the movable plate 5 which face each other, and a mold M is constituted by both of them. A toggle mechanism 8 is arranged between the end plate 2 and the movable platen 5, and the toggle mechanism 6 is moved by a hydraulic cylinder 9 arranged at the center of the end plate 2, whereby the movable platen 5 is moved. It is designed to be moved, clamped, and opened. Further, behind the stationary platen 1, there are provided an injection cylinder for holding the molten plastic raw material, and a screw which is installed in the injection cylinder and injects the plastic raw material from the injection cylinder into the mold through the nozzle 10. A series of operations, that is, a closing operation of the mold M, a clamping operation at the time of injection, an opening operation of the mold M, and the like are continuously performed while controlling the moving speed, and the pressure applied to the screw is controlled. By controlling the resin pressure in the mold during solidification to an appropriate value, a dense molded product is obtained.

By the way, in recent years, in order to meet the demand for things such as compact discs that require precise molding, or those that require thick and precise molding, the mold volume is contracted after injection, and the mold is further clamped. There is a method (compression molding method) for performing stronger compression. This compression molding method includes
Fill the mold with resin while the toggle is not fully extended,
After that, the sandwich press method that extends the toggle to perform mold clamping, making the first mold clamping force relatively weak,
There is a low-links method in which after the resin is filled, a portion of the cavity expanded by the injection pressure of the resin is further pressed and compressed. All of these compression methods are methods in which the entire movable die is moved with respect to the fixed die (overall compression method). For example, when the thickness of the molded product is uneven, the compression ratio is the thickness of the thin portion. Limited and cannot be compressed sufficiently. Therefore, there is a micro-molder method in which only the core portion forming the cavity of the mold is partially movable, and the moving plate is provided with a hydraulic device (hydraulic cylinder) that compresses only the core portion.

[Problems to be Solved by the Invention] By the way, in the micromolder method compression device, unless the movement of the piston of the hydraulic cylinder is restricted by the stopper, for example, for some reason, the injection of the resin into the cavity is properly performed. If it is not done and the injection amount is abnormally smaller than the specified amount, or if it is not injected at all, the core part may collide with the mold and partly strongly press it to break the mold. Further, even if the prescribed amount is injected, the compression margin is not accurately set, so that the product dimensions are likely to vary.

Therefore, in the conventional compression device, a stopper is provided inside the mold to regulate the movement of the piston. However, the internal structure of the mold becomes so complicated that the manufacturing cost becomes high, and the mold once It is not easy to change the stopper position after assembling to the mounting board, and it is difficult to finely adjust.

The present invention provides a compression device for an injection molding machine, which can easily finely adjust the forward limit and the backward limit of a piston of a compression cylinder, and has a simple mold internal structure and low manufacturing cost. To aim.

[Means for Solving the Problems] In the compression device of the present invention, the moving platen is moved by the mold clamping device with respect to the fixed platen, and the molds clamped on the movable platen and the fixed platen are clamped. In the molding machine, a piston of a compression cylinder to which a mold is attached is installed in the moving plate, and a piston rod having a diameter smaller than the piston is connected to the rear end of the piston so as to project rearward of the moving plate. A first stopper is provided on the rear surface of the moving plate to regulate the backward end of the piston by abutting the rear end of the piston so that the position can be adjusted and the piston rod is inserted from the rear of the moving plate. Is provided with a second stopper, which comes into contact with the back surface of the movable plate or the rear end of the first stopper and regulates the forward limit of the piston, so that the position of the second stopper can be adjusted.

[Operation] Since the compression device of the present invention has the first stopper that restricts the backward limit of the piston and the second stopper that restricts the forward limit of the piston, both positions of the forward limit and the backward limit of the mold are set. It is possible to accurately set the compression allowance while accurately controlling by the stopper to prevent the collision of the molds when the forward limit stopper is not provided.

Further, the first stopper is provided in a state of being inserted from the rear of the moving platen, while the second stopper is provided on the piston rod protruding from the back surface of the moving platen, and both stoppers are located on the back surface part of the moving platen. Therefore, fine adjustment of each stopper can be easily performed even after the movable die is mounted on the front surface of the movable platen. Of course, since the stopper is not incorporated inside the mold, the internal structure of the mold does not become complicated.

Further, since these stoppers regulate the position of the piston with respect to the moving platen and do not regulate the movement of the moving platen itself, they do not hinder the original movement of the moving platen during injection molding.

[Embodiment] An embodiment of the present invention will be described below 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 denotes a moving plate (corresponding to the moving plate 5 in FIG. 10), which is opposed to the fixed plate 1 (FIG. 10) and is installed between the end plate 2 and the fixed plate 1. 1
2 (4 in FIG. 10) is inserted so as to be movable. The moving plate 11 is formed in a thick plate shape, and the above-described toggle mechanism is interposed between the moving plate 11 and the end plate to drive the moving plate 11. A compression cylinder 13 is formed inside the movable platen 11. That is, in the center of the movable platen 11, a through hole 14 that opens to the front and rear surfaces (hereinafter, the side facing the mold is the front surface and the end plate side is the rear surface) has a diameter that increases from the rear surface side to the front surface side. First step 15 and second step 16
Is formed with. An annular holding member 17 is fixed to the second step 16 by a bolt 18, and as a result, a reduced diameter step from the rear surface to the front surface is formed in the through hole 14, and the portion sandwiched by these steps is the hydraulic chamber 19. It has become.
A sliding member 23, in which a small diameter portion (piston rod) 20, a piston 21, and a piston rod 22 are integrally formed by a step similar to that of the through hole 14, is annularly mounted in the through hole 14, and is attached to the front surface of the piston rod 22. The core rod 24 is fixed by bolts 25. Oil passages 26 and 27 communicating with an external hydraulic source are opened in the front and rear of the hydraulic chamber 19, and by supplying hydraulic pressure to the oil passages 26 and 27, the piston 21 can be moved forward and backward. There is.

A cylindrical first stopper 28 that restricts the retracted position of the sliding member 23 is formed in the small diameter portion on the rear surface side of the through hole 14, and is a fine screw thread formed on the inner surface of the through hole 14 and the outer surface of the first stopper 28. It is screwed by 29 and is attached to the movable platen 11 so that its position can be adjusted. The first stopper 28 is set so that its rear end projects from the through hole 14, and a key 31 extending forward and backward is attached to the projecting portion 30, while the first stopper 28 is provided around the rear surface opening of the through hole 14. Is a sprocket 32 having an inner groove that fits into the key 31,
The support plate 33 is attached while being prevented from moving back and forth. The sprocket 32 is connected to a drive shaft (not shown) by a chain. The thickness of the piston 21 is set 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 screw 34 is formed on the outer peripheral surface of the small diameter portion 20, and a positioning nut (second stopper) 35 for restricting the forward limit of the sliding member 23 is screwed onto the fine screw 34. A slit 36 is formed in the positioning nut 35, and after the nut is rotated, the slit 36 is compressed by a bolt 37 to elastically deform the nut 35 to prevent its movement.

Inside the sliding member 23, the cylinder 3 for projecting to the rear end side is provided.
9 is provided, and a housing chamber 41 that projects and projects the plate 40 is formed on the front end side with the front surface opened. The protrusion cylinder 39 has a hydraulic chamber 42 formed by extending in the front-rear direction.
And a second piston 43 fitted in the hydraulic chamber 42. The hydraulic chamber 42 is formed with an oil passage 44 (the rear end side is not shown) opened at the front and rear ends thereof. The second piston 43 is connected to the projecting plate 40 via a piston rod 46, and the projecting plate 40 is provided with five projecting pins 47 arranged at the center and on the circumference of the projecting plate 47. 47 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 protrusion pin 47 is precisely aligned. The dog 38 is fixed to the second piston 43, and the dog 38 is inserted through the rear wall of the hydraulic chamber 42 and protrudes toward the rear surface of the moving platen 11.
Along with the movement of 3, the limit switch (not shown) that is appropriately provided on the moving board 11 is operated. Incidentally, reference numeral 45 is an oil passage for supplying lubricating oil around the dog 38.

A mold mounting plate 51 is slidably supported by a tie bar 12 on the front side of the moving plate 11. An insertion hole 52 having a diameter smaller than that of the piston rod 22 and a diameter slightly larger than that of the core rod 24 is formed at the center of the die mounting plate 51, and the outer diameter of the insertion hole 52 is substantially the same as that of the piston rod 22 around the rear side opening. An equal annular step 53 is formed, and a spacer ring 54 is detachably attached thereto. Then, the mold mounting board 51 and the piston rod 22 are formed with bolt holes 56 for the bolts 55 for fixing the two through the step 53, and the mold mounting board 5
A bolt hole 58 for a bolt 57 for fixing the two is formed in the 1 and the movable platen 11.

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

First, a mounting method when the entire surface is compressed will be described. When performing full compression, as shown in the upper half of FIG. 1, a spacer ring 54 is arranged on the annular step 53,
The bolt 55 is inserted into the bolt hole 56 to attach the die mounting plate 51 to the piston rod 22, while the die mounting plate 51 is attached.
The bolt 57 for connecting the moving board 11 to the moving board 11 is removed.

Next, the first stopper 28 and the second stopper 3 that determine the backward limit and the forward limit of the sliding member 23 relative to the movable platen 11.
Adjust 5. That is, when the drive shaft is driven to rotate the sprocket 32 through the chain, the rotation is transmitted to the first stopper 28 by the engagement of the inner groove of the sprocket 32 and the key 31, and is moved in the front-back direction by the fine screw 29. It 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, since the die mounting plate 51 is also pushed by this protruding amount, a gap is formed between the mold mounting plate 51 and the moving plate 11 (third part).
See figure). The second stopper 35 is adjusted by rotating the positioning nut 35 and tightening the bolt 37. The clearance between the first stopper 2 and the second stopper 35 is the margin for movement of the piston 21. The movable die 7 is fixed to the attachment surface of the die attachment board 51 with fixing bolts or the like.

The injection molding process of full compression will be described below with reference to FIGS.
It will be described with reference to the drawings. The toggle mechanism is operated to move the movable platen 11 forward so as to form a cavity between the movable mold 7 and the fixed mold 6 (mold clamping step, see FIG. 3). Here, the mold 6,7
There is a compression margin between each other. Next, the resin is injected from the nozzle 10 of the fixed mold 6 into the cavity, and the compression cylinder 13 is operated to move the mold mounting plate 51 to perform compression after injection or at an appropriate timing during injection (( Compression step, see FIG. 4). In the compression process, the core rod 24 and the mold mounting plate 51 move forward integrally,
The pressure is evenly applied 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 set precisely. After the resin is solidified, the toggle mechanism is activated and the movable platen 11 is retracted to reach the protruding position with the product attached to the movable die 7 (die opening step). Here, the ejecting cylinder 39 is actuated to move the ejecting plate 40 forward, the ejecting pin 47 protrudes from the core rod 24, and the ejector pin 50 provided on the movable die 7 is ejected to eject the product (ejection step, fifth step). See figure). After this,
Both the ejecting cylinder 39 and the compressing cylinder 13 are returned to their original positions, and the mold clamping process is started again.

Next, a mounting method for core compression will be described with reference to the lower half of FIG. Remove the bolt 55 that joins the mold mounting plate 51 and the piston rod 22, and then remove the spacer ring 54.
The mold mounting plate 51 is fixed to the moving plate 11 by removing the bolts and inserting the bolts 57 into the bolt holes 58. In this case, the bolts 55 and 57 are exposed on the front surface of the mold mounting board 51, and can be easily attached and detached. Further, since the mold mounting board 51 is supported by the tie bar 12 and the moving board 11 can be moved by the toggle mechanism, it is easy to open both. As shown in FIG. 6, a movable die 7 a is used for compressing the core, and the core die 7 b is fixed to the core rod 24. The adjustment method of the stoppers 28 and 35 is the same as that in the case of full compression, and is performed in the order of FIGS. 6 to 7. In this case, since the mold mounting plate 51 and the core rod 24 are separated from each other, when the first stopper 28 is advanced, the piston rod 22 projects to the annular step 53, and the core rod 24 projects from the mold mounting plate 51. As the core die 7b moves forward, the second stopper 35 moves the core rod 24
And, the advance position of the core mold 7b is restricted.

The core compression injection molding process will be described below with reference to FIGS. 7 to 9. The mold clamping process is the same as the full compression, but no compression margin is required between the molds 6 and 7a (No. 7).
See figure). Next, injection is performed, the compression cylinder 13 is operated, and the compression process is performed. In this case, the core mold 7b
Since only the mold is relatively moved with respect to the mold 7a to compress the cavity, it is possible to partially perform sufficient compression even with a shape such that only the central portion is thick and the peripheral portion is thin, as illustrated. it can. The fact that the cavities before and after compression can be set precisely by both stoppers 28 and 35 is the same as in the case of full compression. The mold opening and projecting steps are the same as above.

In the ejecting device as described above, since the ejecting hydraulic cylinder 39 is installed inside the piston 21 of the compressing hydraulic cylinder 13, the piston rod 46 may be relatively short, and therefore a small diameter is sufficient. Can withstand bending stress. Further, for the same reason, the weight of the members driven by the projecting hydraulic cylinder 39 can be reduced, so that the moment of inertia of these members is small,
It is possible to shorten the time required to take these in and out,
The molding efficiency can be increased. In addition, the bush 49 attached to the opening of the pin hole 48 allows the projecting pin 47 to be precisely centered, so that the projecting pin 47 can be accurately projected, and the projecting pin 47, the projecting plate 40, and the piston rod 46 are biased. It prevents the load from being applied.

Further, in this embodiment, when the mold mounting plate 51 is attached to the working end (piston rod) 22, the compression device compresses the mold mounting plate 51 for full compression, and when the connection is removed, the core of the mold is removed. Core compression can be performed by pressing only the part. Therefore, if the shape of the molded product is relatively simple and only the entire surface needs to be compressed, it is possible to mass-produce a plurality of products in one step by arranging the cavity on the entire surface of the mold, and only the central part should be thick. For those with complicated shapes, core compression can be used to obtain sufficient compression, and can be used properly according to the purpose. Further, the insertion hole 52 of the die mounting plate 51 is made smaller in diameter than the outer diameter of the operating end 22, and an annular step 53 larger than the outer diameter of the operating end 22 is formed on the peripheral edge portion of the insertion hole 52 on the operating end 22 side. The spacer 5 is provided on the step 53 between the mold mounting plate 51 and the working end 22.
By fixing the mold mounting plate 51 and the operating end 22 with the bolts 55 sandwiching the four, the work mounting work and the efficiency can be reduced, and at the same time, the space between the members can be improved. There is an advantage that a molded product of good quality can be obtained without rattling and switching between full compression and core compression is easy.

[Effects of the Invention] As described in detail above, according to the compression device of the present invention, in the case where there is no advance limit stopper by the first stopper that regulates the retreat limit of the piston and the second stopper that regulates the advance limit. While preventing the collision of such molds,
It is possible to accurately set the compression margin, reduce variations in product dimensions, and obtain high-quality molded products.

Further, since both stoppers are provided on the back surface of the movable platen, fine adjustment of each stopper is easy even after the movable die is mounted on the front surface of the movable platen. Further, since the stopper is not incorporated inside the mold, the internal structure of the mold does not become complicated.

Further, since both stoppers do not hinder the original movement of the movable platen, smooth and quick operation can be performed during injection and compression without requiring stopper release operation or the like.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a compression device of an injection molding machine according to an embodiment of the present invention, FIGS. 2 to 9 are schematic views showing its operation, and FIG. 10 is a general toggle type injection molding machine. 2 is a schematic diagram showing the basic structure of FIG. 11 ... moving board, 13 ... compression cylinder, 21 ... piston, 28 ... first stopper, 35 ... second stopper.

Claims (1)

[Claims] 1. A movable platen (11) is moved with respect to a fixed platen (1) by a mold clamping device so that a mold (6, 7) attached to the movable platen (11) and the fixed platen (1) respectively. In an injection molding machine that performs mold clamping, a piston (21) of a compression cylinder (13) to which a mold (7b) is attached is installed in the moving plate (11), and the piston is provided after the piston (21). A piston rod (20) having a diameter smaller than that of the piston (21) is connected to the end of the movable plate (11) so as to project to the rear of the movable plate (11).
A first stopper (28) that abuts the rear end of the piston (21) and restricts the retreat limit of the piston (21) is provided on the rear surface of (1) so as to be positionally adjustable and inserted from the rear of the movable platen (11). On the other hand, the piston rod (20) is provided with a second stopper (35) for contacting with the rear surface of the moving plate (11) or the rear end of the first stopper (28) to restrict the forward limit of the piston (21). A compression device for an injection molding machine, which is provided so that its position can be adjusted.