JPH0122138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] This invention relates to a mold clamping device for an injection molding machine or a die casting machine.

[Prior art and its problems]

Generally, in mold clamping devices such as injection molding machines,
In order to prevent the mold from opening due to the pressure inside the mold during injection, a large mold clamping force is required during mold clamping.On the other hand, after the molded product has solidified, the mold is quickly closed by the stroke necessary to eject it. The operation of opening and opening the mold requires a high speed of opening and closing the mold in order to ensure a sufficient stroke to take out the molded product and to improve productivity.

However, in recent years, demand for injection molding machines and the like has shown a tendency to increase in size, and for this reason, hydraulic mold clamping devices have reduced machine weight and installation area, and have a large capacity, as well as hydraulic drive sources. It has become important to reduce manufacturing costs and operating costs by reducing the size and speed of operation. Therefore, instead of moving the mold and clamping the mold using a single cylinder, a boost cylinder moves the movable die plate to open and close the mold, and a separate mold clamping cylinder (hydraulic cylinder) is used to open and close the movable die plate. A method has been implemented in which the mold is clamped by strongly pressing the plate against the fixed die plate.

FIG. 1 is a longitudinal sectional view showing a typical configuration example of a conventional injection molding machine. That is, in FIG. 1, reference numeral 10 indicates a support frame, and a fixed die plate 14 to which a fixed mold 12 is attached is fixed to one end of the support frame 10. Further, at the other end of the support frame 10, a movable die plate 18 to which a movable die 16 is attached is slidably mounted so as to face the fixed die plate 14.
The fixed die plate 14 is provided with a plurality of hydraulic cylinders 20, and tie bars 24 are respectively extended from one side of the internal piston 22 of these hydraulic cylinders 20 toward the movable die plate. These tie bars 24 pass through the insertion holes 26 of the opposing movable die plates 18, and their tips are connected and fixed to the support plate 28. A boost cylinder 30 is fixed to one side of the fixed die plate 14, and the tip of a rod 34 connected to the internal piston 32 of the boost cylinder 30 is appropriately fixed to one side of the movable die plate 18. . Also, tie bar 2
4, a plurality of circumferential grooves 36 are carved into each of the circumferential grooves 36, and a stop ring 38 split into two is removably fitted into one of the circumferential grooves 36.
A threaded portion 40 is formed in a portion of the circumferential groove 36 on the movable die plate 18 side. On the other hand, a half nut 42 that engages with the threaded portion 40 of the tie bar 24 is attached to the side opposite to the surface on which the movable mold 16 is attached to the movable die plate 18 provided with the insertion hole 26 through which the tie bar 24 is inserted. It is provided so as to be movable in a direction substantially perpendicular to the axis of the.

The conventional mold clamping device configured in this manner first moves the movable die plate 18 toward the fixed die plate by supplying pressure oil to one oil chamber 44 of the boost cylinder 30 when closing the mold.
In this way, just before the closing of the fixed mold 12 and the movable mold 16 is completed, the tie bar 24
A stop ring 38 is positioned and fitted in one of the circumferential grooves 36 cut in the die according to the dimensions of the mold, and is engaged with the opening edge of the insertion hole 26 of the movable die plate 18. At this time, moving die plate 1
A half nut 42 provided at 8 is moved in a direction substantially perpendicular to the axis of the insertion hole 26 to mesh with a threaded portion 40 formed on a part of the tie bar 24. Therefore, in this case, the tie bar 24 is integrally connected to the movable die plate 18 by the half nut 42. Next, fixed die plate 1
By supplying pressure oil to one oil chamber 46 of the hydraulic cylinder 20 provided at 4 and moving the tie bar 24 directly to the fixed die plate 14 side, the movable die plate 18 is moved to the fixed die plate 14 side and fixed. It is possible to achieve mold clamping between the mold 12 and the movable mold 16.

The mold clamping device configured in this manner can advance the half nut 42 in the middle of the stroke of the boost cylinder 30 to reliably engage the movable die plate 18 with the tie bar 24 during the mold clamping operation. At the end of the stroke of 30, the movable die plate 18 is completely connected to the tie bar 24, and pressure oil is immediately supplied to the hydraulic cylinder 20 to enable mold clamping.
It has the advantage of improving productivity.

However, today, injection molding machines, etc., tend to become larger and larger, and there is a strong demand for high-mix, low-volume production.As a result, they are lighter and smaller, making it easier to change molds, and reducing costs. This type of mold clamping device is becoming more and more desired. Considering the conventional mold clamping device mentioned above from this point of view, in order to facilitate the replacement of many types of molds, the mold clamping position differs depending on the mold thickness, so the inside of the tie bar is used. A large number of circumferential grooves are cut into the stop ring so that the setting position of the stop ring can be changed. Therefore, when a circumferential groove is carved in the middle part of the tie bar in this way, the stress applied to the tie bar during mold clamping is concentrated in the circumferential groove, and as a result, the strength of the tie bar is substantially increased by cutting the circumferential groove. Since the diameter of the tie bar is determined by the diameter of the installed part, the diameter of the entire tie bar must be made larger than necessary, and the dimensions of the hydraulic cylinder, fixed and movable die plate, half nut, and support plate also become larger. It becomes difficult to satisfy the above-mentioned demands.

Therefore, in order to overcome the above-mentioned problems in manufacturing the tie bars, a mold clamping device was proposed in which the tie bars are not provided with a stop ring, as shown in FIG. That is, the mold clamping device shown in FIG. 2 has most of its basic configuration in common with the mold clamping device shown in FIG. A shaft 48 is provided protruding from the center of the side where the shaft 42 is provided, and the tip of the shaft 48 is connected to the support plate 28.
A plurality of circumferential grooves 52 are cut into the tip of the shaft 48, and a stop ring 54 is fitted into one of the circumferential grooves 52. This is what I did. The other components are the same as those of the mold clamping device shown in FIG. 1, so the same reference numerals are given to the same components and detailed explanation thereof will be omitted.

In the mold clamping device shown in FIG. 2 configured as described above, when performing a mold clamping operation in the same manner as the above-described mold clamping device shown in FIG. Immediately before mold closing is completed, the stop ring 54 positioned on the shaft 48 protruding from the movable die plate 18 locks onto the support plate 28, so that the half nut 42 provided on the movable die plate 18 is inserted into the insertion hole 26. can be moved in a direction substantially perpendicular to the axis of the tie bar 24 to engage with a threaded portion 40 formed on a part of the tie bar 24.

The mold clamping device configured in this manner can stabilize the strength of the tie bars and downsize the tie bars and related components, but the support plate 28
A shaft 48 further protrudes outward from the shaft 4.
8 and the support plate 28 are engaged with each other with a strong tensile force through the stop ring 54 when the mold is clamped, so the structure must have a sufficient diameter and wall thickness. Therefore, even in this type of mold clamping device,
It is necessary to design the structural members located outside the movable die plate 18, which do not directly act on mold clamping, to be stronger than necessary, and there is a limit to the miniaturization and weight reduction of this type of mold clamping device.

In addition, with the conventional mold clamping device mentioned above, when replacing the mold, it takes time and effort to replace the stop ring every time the thickness of the mold changes, so automation of this type of mold thickness adjustment is an advantage in improving work efficiency. requested. In the past, various automatic mold thickness adjusting devices have been proposed and put into practice, but all of them are unsatisfactory because of their complicated configurations and increased manufacturing costs. Therefore, today, mold clamping devices are becoming more applicable to the automation of the entire device, improving performance, reducing the total weight of the device, realizing miniaturization, and reducing the manufacturing and operating costs of the device. There is a demand for further reductions.

[Purpose of the invention]

An object of the present invention is to configure the tip portion of the tie bar, which is not directly affected by the mold clamping force during the mold clamping operation, to have a small diameter, and to configure a stepped portion at the boundary thereof, while forming a stepped portion around the opening of the tie bar insertion hole of the die plate. By setting a stopper that engages with the stepped portion adjacent to the provided half nut, it is possible to reduce the size and weight of the tie bar, and also to reduce the weight of the structural members located outside the movable die plate, as well as to reduce the installation area. We have developed a mold clamping device that can reduce manufacturing costs and reduce operating costs by making it easier to change molds, as well as adjusting the mold thickness when changing molds. It is on offer.

[Structure of the invention]

A mold clamping device according to the present invention includes: a fixed die plate that holds a fixed mold; a movable die plate that holds a movable mold; a means for moving the movable die plate forward and backward relative to the fixed die plate; Immediately before the plate approaches the stationary die plate and the stationary die and movable die are closed, the mold clamping device includes a tie bar that is coupled and fixed to the movable die plate to clamp the die, the tip of the tie bar having a narrow end. A half nut is movably provided on the opposite side of the movable die plate to the axis of the tie bar insertion hole at a substantially right angle to the axis of the tie bar insertion hole. A stopper is provided through which the extended guide rod is inserted, and a threaded portion is provided on the outer periphery of the tip of the tie bar to engage with the half nut, and the stopper locks a stepped portion formed at the boundary between the guide rod and the tie bar. The present invention is characterized in that a half nut is engaged with the threaded portion of the tie bar to couple and fix the tie bar and the movable die plate.

That is, in the present invention, as a means for engaging and coupling and fixing the movable die plate and the tie bar at the time of mold clamping, the length of the tie bar is adjusted so as to mutually couple the movable die plate and the fixed die plate at the time of mold clamping. By setting a sufficient degree and extending a small-diameter guide rod as a guide to the tip of this tie bar, the step formed at the boundary between the guide rod and the tie bar can be used as a stopper member. At the same time, the means for locking and connecting tie bars to the tie bar insertion holes provided in the movable die plate can be arranged in a compact manner, making it possible to make the tie bar design smaller and significantly lighter than conventional mold clamping devices. In addition, it is possible to provide a high-performance and highly reliable molding machine that can quickly respond to mold replacement work and mold thickness adjustment.

In this case, it is advantageous in manufacturing if the guide rod is configured to be detachably connected to the tip of the tie bar.

In the mold clamping device described above, the stopper consists of a plurality of stopper pieces each having a semicircular notch into which the guide rod can be inserted. By providing the piece so that it can move forward and backward with respect to the guide rod by automatic moving means, automatic mold thickness adjustment can be effectively achieved in a small space.

Furthermore, in the device of the present invention, by connecting the tips of the guide rods to each other with a connecting member, synchronization when moving the tie bars during mold clamping can be easily and reliably achieved. In addition,
The durability against engagement with the stopper can be improved by appropriately providing reinforcing means to the tip of the tie bar.

[Embodiments of the invention]

Next, regarding an example of the mold clamping device according to the present invention,
A detailed description will be given below with reference to the accompanying drawings.

3 and 4 show an embodiment of a mold clamping device according to the present invention. That is, in FIG. 3, reference numeral 60 indicates a support frame;
A fixed mold 6 is mounted on one end of this support frame 60.
The fixed die plate 64 with 2 attached is fixed,
Further, on the other end of the support frame 60, a movable die plate 68 to which a movable die 66 is attached is slidably mounted opposite to the fixed die plate 64.
The fixed die plate 64 is provided with a plurality of (four in this embodiment) hydraulic cylinders 70, and each tie bar 74 is moved in the direction of the die plate 68 from the surface of the internal piston 72 of these hydraulic cylinders 70 on the movable die plate 68 side. It will be extended to Further, a boost cylinder 76 is fixed to one side of the fixed die plate 64, and the tip of a rod 80 connected to an internal piston 78 of the boost cylinder 76 is appropriately fixed to one side of the movable die plate 68. .

The above configuration is the same as that of a conventional mold clamping device. However, in the present invention, during the mold clamping operation, the tie bars 74 connected between the fixed die plate 64 and the movable die plate 68 are limited to only the portion on which the mold clamping force is substantially applied. This tie bar 7 has a strong structure.
The tie bar 74 serves as a guide member at the tip of 4.
A guide rod 82 with a smaller diameter is extended. Therefore, in one embodiment of the mold clamping device according to the present invention, each tie bar 7 is attached to the movable die plate 68.
A half nut 86 is provided on the opposite side of the movable die plate 68 from the surface on which the movable mold 66 is attached, and the half nut 86 is movable in a direction substantially perpendicular to the axis of the through hole 84. Further, adjacent to this half nut 86, a guide rod 82 is provided protruding from the tip of the tie bar 74.
Insert the guide rod 82 and tie bar 7.
A stopper 90 capable of locking the stepped portion 88 formed at the boundary with the tip of the die plate 4 is provided, and this stopper 90 is appropriately fixed to the movable die plate 68. Therefore, in this case, a threaded portion 92 that engages with the half nut 86 is carved on the outer periphery of the tip end of the tie bar 74. Furthermore, a connecting member 94 can be coupled to the tip of the guide rod 82, if necessary, for the purpose of synchronizing the movement of each tie bar 74 during a mold clamping operation.

In this embodiment, the guide rod 82 extending from the tip of the tie bar 74 is
Although it can be configured by integral molding with the tie bar 74, it is advantageous in manufacturing if it is connected to the tip of the tie bar 74, which is processed as a separate member, by means such as screwing. Further, in order to maintain strength against engagement with the stopper 90, the tip of the tie bar 74 is preferably provided with a reinforcing material or a reinforcing process as appropriate.

The mold clamping device in this embodiment configured as described above moves the movable die plate 68 toward the fixed die plate 64 by supplying pressure oil to one oil chamber 96 of the boost cylinder 76 when closing the mold. At this time, the guide rod 82 protruding from the tip of the tie bar 74 moves while sliding on the stopper 90, and the tip of the tie bar 74 is smoothly inserted into the insertion hole 84 of the movable die plate 68.
Next, just before the mold closing of the fixed mold 62 and the movable mold 66 is completed, the step 88 formed at the tip of the tie bar 74, that is, at the boundary with the guide rod 82, is locked with the stopper 90 (the fourth (see figure). At this time, the half nut 86 provided on the movable die plate 68 is inserted into the insertion hole 84 by the moving means 98.
By moving it in a direction substantially perpendicular to the axis of the diver 74, it can be engaged with a threaded portion 92 formed on the diver 74. As a result, the tie bars 74 can be easily coupled and fixed to the movable die plate 68 as in the conventional mold clamping device. After that, if pressure oil is supplied to one oil chamber 100 of the hydraulic cylinder 70 provided in the fixed die plate 64, the tie bar 7
4 directly to move the movable die plate 68 toward the fixed die plate 64,
It is possible to achieve mold clamping between the fixed mold 62 and the movable mold 66.

In addition, in the mold clamping device according to the present invention, in order to perform so-called mold thickness adjustment in which the coupling and fixing position of the movable die plate 68 to the tie bar 74 is adjusted according to the thickness of the mold when replacing the mold, the stopper 9
This can be easily realized by changing the operating position of 0.

Therefore, in the present invention, a stopper can be constructed as a mold thickness adjusting means, as shown in FIG. 5, for example. The embodiment shown in FIG. 5 is characterized in that a stopper piece 102 is provided on the guide rod 82 so that it can move forward and backward in a direction substantially perpendicular to the axis of the guide rod 82. In this case, the stopper piece 102 has a substantially semicircular notch 104 that can slide into the guide rod 82, and the piston rod 1 of the pressure cylinder 108 whose upper end of the stopper piece 102 is fixed to the support frame 106.
Fixed at 10. A plurality of stopper pieces 102 configured as described above are installed on a common support frame 106 at predetermined intervals in the axial direction of the guide rod 82, and this support frame 106 is attached to the movable die plate 6.
Install it on 8. In this way, a plurality of stopper pieces 10
2 relative to the guide rod 82, one of the stopper pieces 102 can be selectively used in combination depending on the thickness of the mold, and the stopper pieces 102 can be advanced in a direction perpendicular to the guide rod 82 by automatic control operation. , the movable die plate 68 can be positioned, thereby making it possible to properly adjust the mold thickness.

〔Effect of the invention〕

As is clear from the embodiments described above, the mold clamping device according to the present invention sets the substantial length of the tie bar to a length that is coupled and fixed between the fixed die plate and the movable die plate during mold clamping. However, since the tie bar has a structure in which a small-diameter guide rod extends from the tip thereof, the actual size of the tie bar can be shortened, and the step formed at the boundary between the tie bar and the guide rod can be shortened. By using the tie bars as means for engaging with the moving die plate, it is possible to reduce the size and weight of the device without causing any deterioration in the strength of the tie bars due to machining.

In particular, in the device of the present invention, the guide rods protruding from the tips of the tie bars only have the function of guiding the tie bars into the insertion holes of the movable die plate. It is possible to easily reduce the size and weight of the connecting member.

In addition, in the device of the present invention, the end edge of the tie bar is directly formed as an engaging part for the stopper without providing a stop ring or the like on the tie bar, so the stopper for the tie bar is easily and less attached to the movable die plate together with the half nut. Can be installed in any space. In addition, this stopper is an automatically controllable stopper piece that is spaced a predetermined distance along the axial direction of the guide rod and moves back and forth in a direction perpendicular to the axis, even when making mold thickness adjustments that are necessary when replacing the mold. With this configuration, automatic mold thickness adjustment can be easily realized.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of the configuration of a conventional mold clamping device, FIG. 2 is a vertical cross-sectional view showing a modification of the conventional mold clamping device, and FIG. 3 is a vertical cross-sectional view showing a modification of the conventional mold clamping device. A plan sectional view of the mold in the open state showing the embodiment, FIG.
FIG. 5 is a front sectional view showing an embodiment of the mold thickness adjusting means used in the mold clamping device according to the present invention. 10... Support frame, 12... Fixed mold, 14...
Fixed die plate, 16... Moving mold, 18... Moving die plate, 20... Hydraulic cylinder, 22... Internal piston, 24... Tie bar, 26... Insertion hole, 28
...Support plate, 30...Boost cylinder, 32...Internal piston, 34...Rod, 36...Circumferential groove, 38...
Stop ring, 40...Threaded part, 42...Half nut, 44...Oil chamber, 46...Oil chamber, 48...Shaft, 50
...Through hole, 52...Circumferential groove, 54...Stop ring,
60... Support frame, 62... Fixed mold, 64... Fixed die plate, 66... Moving die, 68... Moving die plate, 70... Hydraulic cylinder, 72... Internal piston, 74... Tie bar, 76... Boost cylinder, 78... Internal piston, 80... Rod, 82...
Guide rod, 84... Insertion hole, 86... Half nut, 88... Step part, 90... Stopper, 92... Threaded part, 94... Connecting member, 96... Oil chamber, 98... Moving means, 100... Oil chamber, 102... Stopper piece, 104
...notch, 106...support frame, 108...pressure cylinder, 110...piston rod.

Claims (1)

[Scope of Claims] 1. A fixed die plate that holds a fixed mold, a movable die plate that holds a movable mold, means for moving the movable die plate forward and backward relative to the fixed die plate, and the movable die plate In a mold clamping device comprising a tie bar that approaches the fixed die plate and is coupled and fixed to the movable die plate to clamp the mold immediately before the fixed die and the movable die are closed, the tie bar has a small diameter at its tip. A guide rod is extended, a half nut is movably provided on the opposite side of the movable die plate to the die mounting surface approximately perpendicular to the axis of the tie bar insertion hole, and a half nut is provided adjacent to the half nut and extended to the tip of the tie bar. A stopper is provided through which the guide rod is inserted, and a threaded portion is provided on the outer periphery of the tip of the tie bar to engage with the half nut, and the stopper locks the stepped portion formed at the boundary between the guide rod and the tie bar, and A mold clamping device characterized in that a half nut is engaged with a threaded portion of the tie bar and a movable die plate to couple and fix the tie bar and the movable die plate. 2. The mold clamping device according to claim 1, wherein the guide rod is detachably connected to the tip of the tie bar. 3. In the mold clamping device according to claim 1, the stopper consists of a plurality of stopper pieces each having a semicircular notch into which the guide rod can be inserted;
A mold clamping device in which these stopper pieces are arranged at predetermined intervals in the axial direction of a guide rod, and each stopper piece is provided so as to be movable forward and backward with respect to the guide rod by an automatic moving means. 4. The mold clamping device according to claim 1, wherein the respective tips of the guide rods are connected to each other by a connecting member. 5. The mold clamping device according to claim 1, wherein a reinforcing means is provided at the tip of the tie bar.