JP3764425B2 - Molding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molding machine such as an injection molding machine or a die casting machine, and more particularly to a technique related to a mold opening / closing mechanism of a molding machine having a configuration in which three tie bars are provided.
[0002]
[Prior art]
A mold opening / closing mechanism in a molding machine such as an injection molding machine includes a fixed die plate mounted with a fixed mold, a lower end side fixed, a holding plate mounted with a mold opening / closing drive source, a fixed die plate and a holding plate It is common to have a configuration with a tie bar spanned between and a movable die plate that is equipped with a movable die and is inserted and guided by the tie bar so that it can move forward and backward. In many cases, the movable die plate is driven forward and backward by transmitting the driving force of a mold opening / closing drive source including a hydraulic cylinder to the movable die plate via a toggle link mechanism.
[0003]
In such a mold opening / closing mechanism, a machine having a configuration in which both ends of the four tie bars are fixed to the four corners of the fixed die plate and the holding plate and the tie bars are inserted into the four corners of the movable die plate is conventionally known. In general, an injection molding machine having a configuration in which the number of tie bars is three is also known (see Patent Document 1).
[0004]
In the technique described in the above-mentioned patent document, each of the three tie bars is disposed at a substantially equal distance and a substantially equal angular interval with respect to the mold center, and the location of the clamping force acting on the movable die plate ( The position of the coupling link to the movable die plate in the toggle link mechanism) is 3 locations, and the location where each mold clamping force is applied is approximately equal to the center of the die so that it is located at an intermediate angular position between adjacent tie bars. They are arranged at a distance and at substantially equal angular intervals. With such a configuration, it becomes possible to reduce the clamping force (variation of compressive stress) on the disk-shaped molded product in the mold (if this point is necessary, the applicant of the present application first) (See the proposed Japanese Patent Application No. 2001-343502).
[0005]
[Patent Document 1]
JP-A-8-332657 [0006]
[Problems to be solved by the invention]
In the above-described prior art (Patent Document 1 and Japanese Patent Application No. 2001-343502), the three tie bars and the above-mentioned three places of the clamping force acting on the movable die plate have an angular interval of about 60 °. Has been placed. For this reason, in the mold clamping state where the toggle link mechanism is extended, the reaction force of the tie bar due to the extension of the three tie bars by the mold clamping force acts on the fixed die plate and the mold clamping by the toggle link mechanism. The location where the force acts on the movable die plate is shifted by approximately 60 ° from each other. Therefore, as shown in FIG. 3, for a molded product 51 formed between a fixed mold mounted on a fixed die plate and a movable mold mounted on a movable die plate, a fixed die plate is used. As shown on the right side of FIG. 3, the stress concentrates on the portion near the tie bar 52 from the side, and from the movable die plate side, the clamping force by the toggle link mechanism acts as shown on the left side of FIG. Stress concentrates on a portion close to the point 53. As a result, when the molded product is, for example, a disk, there is a problem that stress distribution differs between the front and back surfaces of the disk, and warpage along the circumferential direction is likely to occur.
[0007]
In addition, since a link group of a toggle link mechanism including an A link, a B link, and a C link is arranged at an intermediate position between the three tie bars 51, it is surrounded by the three tie bars 51 and the three link groups. It is difficult to insert a hand or a tool at the center, and for this reason, it is very difficult and troublesome to maintain the cross head that combines the C links of the three link groups and the ball screw mechanism that drives the cross head. There was also a problem that it took.
[0008]
The present invention has been made in view of the above points, and an object of the present invention is to enable uniform stress distribution on the front and back of a molded product in a molding machine having a mold opening / closing mechanism of three tie bars. The purpose is to facilitate maintenance of the head and the ball screw mechanism.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention
A fixed die plate with a fixed die, a holding plate with a mold opening / closing drive source, a tie bar spanned between the fixed die plate and the holding plate, and a movable die are inserted into the tie bar.・ Equipped with a movable die plate that can be guided back and forth,
In the molding machine in which the number of the tie bars is three and each tie bar is disposed at substantially equal distances and substantially equal angular intervals with respect to the mold center,
Assuming that there are three places where the mold clamping force acts on the movable die plate, each place where the mold clamping force acts is located approximately on the line connecting the mold center and each tie bar, and is approximately equidistant from the mold center. Arranged so that
Take the configuration.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
1 and 2 relate to an embodiment of the present invention, FIG. 1 is a perspective view of a main part of a mold opening / closing mechanism of an injection molding machine according to the present embodiment, and FIG. 2 is a stress on the front and back of a molded product on a disk. It is explanatory drawing which shows distribution.
[0012]
In FIG. 1, 1 is a fixed die plate on which a fixed die (not shown) is mounted, 2 is a holding plate on which a mold clamping servo motor (not shown) as a mold opening / closing drive source is mounted, 3. Three tie bars, 4 spanned between the plate 1 and the holding plate 2 and fixed at both ends to the fixed die plate 1 and the holding plate 2, respectively, are mounted with a movable mold (not shown). A movable die plate 5 inserted and guided through 3 and capable of moving forward and backward is provided with a ball screw mechanism 5 for converting the rotation of a clamping motor (not shown) into a linear motion (in FIG. 6 is a toggle link mechanism that receives the linear motion of the ball screw mechanism 5 and extends or folds to drive the movable die plate 4 forward and backward.
[0013]
In the toggle link mechanism 6, 7 is a crosshead, 8 is an A link, 9 is a B link, and 10 is a C link. The crosshead 7 is driven forward and backward by the ball screw mechanism 5. One end of 10 is rotatably coupled. One end of the A link 8 is rotatably connected to the movable die plate 4, and the B link 9 is rotatably connected to the holding plate 2. The other end of the C link 10 and the other end of the A link 8 are connected to each other. The other end of the B link 9 is rotatably coupled to each other. Three link groups including the A link 8, the B link 9, and the C link 10 are provided, and the three link groups are arranged at intervals of 120 degrees with the crosshead 7 as the center.
[0014]
The three tie bars 3 are provided at 120 degree intervals around the mold center (= the center of the crosshead 7 of the toggle link mechanism 6), and at equal distances from the mold center. Further, on the side of the toggle link mechanism mounting surface of the movable die plate 4, there is a link attachment portion for rotatably connecting the A link 8 of the toggle link mechanism 6 (that is, the location where the mold clamping force acts on the movable die plate 4. ) Are provided at 120 degree intervals around the center of the mold (= the center of the crosshead 7 of the toggle link mechanism 6), and at equal distances from the center of the mold. The action location is located approximately on the line connecting the die center (= the center of the crosshead 7 of the toggle link mechanism 6) and each tie bar 3 (that is, the three clamping forces in the movable die plate 4). The action location is arranged at substantially the same angular position as each of the three tie bars 3 around the center of the mold and inside the machine than the tie bars 3).
[0015]
As described above, in the machine according to the present embodiment, the three tie bars 3 are arranged at substantially equal distances and substantially equal angular intervals with respect to the mold center, and three places of the clamping force acting on the movable die plate 4 are applied. As shown in the figure, the locations where the clamping force acts are arranged at approximately equal distances and approximately equal angular intervals with respect to the mold center. On the other hand, the clamping force acting on the movable die plate 4 is balanced in all directions as compared with the two upper and lower locations. For example, when molding an optical disk substrate, there is no variation in compressive stress and high accuracy. It is possible to mold an optical disk substrate having a thickness accuracy of 5 mm.
[0016]
Further, in the machine of the present embodiment, the three tie bars 3 and the location where the mold clamping force is applied to the movable die plate 4 are arranged at substantially the same angular position with the mold center as the center. In the mold clamping state in which is extended, the reaction force of the tie bar 3 due to the three tie bars 3 being stretched by the mold clamping force causes the clamping force to be applied by the location where the fixed die plate 1 acts and the toggle link mechanism 6. The location 12 acting on the movable die plate 4 is at substantially the same angular position. Therefore, as shown in FIG. 2, the molded product 11 formed between the fixed mold mounted on the fixed die plate 1 and the movable mold mounted on the movable die plate 4 is fixed. From both the die plate 1 side and the movable die plate 4, stress concentrates at substantially the same angular position. As a result, when the molded product is, for example, a disk, the stress distribution is substantially the same on the front and back of the disk, and warpage is less likely to occur.
[0017]
In the machine of this embodiment, each link group of the toggle link mechanism 6 including the A link 8, the B link 9, and the C link 10 is arranged at substantially the same angular position as each tie bar 3, so that the machine It is easy to insert a hand or a tool in the center of the head, and the maintenance of the cross head and the ball screw mechanism that drives the cross head is simple and easy.
[0018]
In the above-described embodiment, a rotary servo motor is used as the mold clamping servo motor, and this rotational force is converted into a linear motion so that the toggle link mechanism is linearly driven. You may make it drive a toggle link mechanism directly with the linear drive force of this linear servomotor using a linear servomotor.
[0019]
【The invention's effect】
As described above, according to the present invention, in a molding machine having a mold opening / closing mechanism of three tie bars, it is possible to make the stress distribution on the front and back of the molded product uniform, greatly contributing to good product molding, and crosshead And ball screw mechanism maintenance can be done easily and easily.
[Brief description of the drawings]
FIG. 1 is a perspective view of a main part of a mold opening / closing mechanism in an injection molding machine according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing stress distributions on the front and back sides of a disk-shaped molded product molded in an injection molding machine according to an embodiment of the present invention.
FIG. 3 is an explanatory view showing stress distributions on the front and back of a disk-shaped molded product molded by a conventional injection molding machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed die plate 2 Holding plate 3 Tie bar 4 Movable die plate 5 Ball screw mechanism 6 Toggle link mechanism 7 Cross head 8 A link 9 B link 10 C link 11 Molded article 12 Location where mold clamping force acts on the movable die plate

Claims (2)

A fixed die plate with a fixed die, a holding plate with a mold opening / closing drive source, a tie bar spanned between the fixed die plate and the holding plate, and a movable die are inserted into the tie bar.・ Equipped with a movable die plate that can be guided back and forth,
In the molding machine in which the number of the tie bars is three and each tie bar is disposed at substantially equal distances and substantially equal angular intervals with respect to the mold center,
Assuming that there are three places where the mold clamping force acts on the movable die plate, each place where the mold clamping force acts is located approximately on the line connecting the mold center and each tie bar, and is approximately equidistant from the mold center. A molding machine characterized in that each is arranged. In claim 1,
In the toggle link mechanism that uses a servo motor as the mold opening / closing drive source and transmits the driving force of the servo motor to the movable die plate, three coupling links to the movable die plate side are provided, and each mold clamping force is provided. A molding machine characterized in that the working part of is formed.

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