Patent ID: 12257754

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described below with reference to the accompanying drawings.

Embodiments

As illustrated inFIG.1, a mold-clamping machine10is a horizontal type mold-clamping machine that includes a base11, a stationary mount13, a mold-clamping mechanism15, a mold opening-and-closing mechanism16, a movable mount18, tie bars19and19, and a constraining mechanism30.

The stationary mount13is fastened on the base11, and supports a stationary mold12.

The mold-clamping mechanism15is placed in parallel with the stationary mount13, and is supported by the base11so as to be freely movable horizontally. The mold-clamping mechanism15includes a piston rod14elongated toward the stationary mold12.

The mold opening-and-closing mechanism16is for moving the mold-clamping mechanism15and the movable mount18.

The movable mount18supports a movable mold17. The movable mount18is placed between the stationary mount13and the mold-clamping mechanism15, and is supported by the base11so as to be freely movable horizontally. The movable mount18is coupled to the piston rod14.

The tie bars19and19extend horizontally from the stationary mount13, and pass completely through the movable mount18and through the mold-clamping mechanism15.

The constraining mechanism30is attached to the mold-clamping mechanism15so as to encircle the tie bars19.

The mold-clamping mechanism15may be any of a hydraulic cylinder, a motor cylinder, and a toggle mechanism. The mold opening-and-closing mechanism16may be any of a hydraulic cylinder and a motor cylinder.

Moreover, the mold opening-and-closing mechanism16may be provided across the stationary mount13and the mold-clamping mechanism15.

Furthermore, the mold opening-and-closing mechanism16may be provided across the base11and the movable mount18(or the mold-clamping mechanism15).

For example, a slider22is mounted on a rail21laid over on the base11, the movable mount18is mounted on the slider22. By providing rollers like steel balls between the rail21and the slider22, the movable mount18can be moved horizontally relative to the base11by slight force.

Still further, for example, the mold-clamping mechanism15may be directly mounted on a slider plate23bonded to a top face of the base11so as to allow the mold-clamping mechanism15to move horizontally relative to the base11.

The present disclosure is not limited to the above schemes which mount the movable mount18on the slider plate23or which mounts the mold-clamping mechanism15on the rail21through the slider22.

In order to ensure the length in the axial direction along the tie bar19(the area of the inner circumference surface), it is desirable that the constraining mechanism30should pass completely through the mold clamping mechanism15and through the movable mount18, and have a tip protruding toward the stationary mount13.

The constraining mechanism30includes, for example, flanges31provided at one-end side, a plurality of bolts32that fastens each flange31to the mold-clamping mechanism8216, and cylindrical portions33that extend along the respective tie bars19from the respective flanges31. The cylindrical portions38encircle lengthwise sections of the respective tie bars19and, as shown inFIG.1. are long enough to extend completely through the mold clamping mechanism15.

Note that a male screw may be provided on the outer circumference surface of the cylindrical portion33, a female screw may be provided on the mold-clamping mechanism15, and the mold-clamping mechanism15may be coupled to the cylindrical portion33by screw-coupling. The screw-coupling scheme can eliminate the flanges31and the bolts32.

As illustrated inFIG.2, the cylindrical portions33that extend from the respective flanges31are sufficiently long.

As illustrated inFIG.3, each cylindrical portion33includes, for example, an outer cylinder34formed of steel, an inner cylinder35formed of steel, and a magnet mechanism36placed between the outer cylinder34and the inner cylinder35.

The magnet mechanism36includes, for example, a plurality of first permanent magnets37provided between the outer cylinder34and the inner cylinder35, electro-magnetic coils38that surround the corresponding first permanent magnet37, and a plurality of second permanent magnets39each provided between the adjoining electro-magnetic coils38and38, and attached to the inner cylinder35. The electro-magnetic coil38corresponds to an electric magnet.

An alnico magnet is suitable for each first permanent magnet37. When a current flows through the electro-magnetic coils38, the temperature of the respective first permanent magnets37inevitably rises. Since an alnico magnet has a Curie point temperature that is 860° C., it can withstand the temperature rise, and is suitable for magnetization inversion (that is to change the direction of magnetization).

Since the second permanent magnets39are not affected by the electro-magnetic coils38, a neodymium (neodymium) magnet that has a Curie point temperature of 300° C. is applicable. The magnetic energy density of a neodymium magnet is 300 kJ/m3which is the magnetic property that is 7.5 times of the magnetic energy density of an alnico magnet which is 40 kJ/m3, thus suitable for each second permanent magnet39.

However, since a neodymium magnet is likely to be rusted, it is isolated from an ambient air by a water shielding film41.

Moreover, the second permanent magnets39are placed in such a way that the N-pole of the one second permanent magnet39faces the N-pole of the adjoining second permanent magnet39, and the S-pole of the one second permanent magnet39faces the S-pole of the adjoining second permanent magnet39.

Actions of the constraining mechanism30that employs the above-described structure will be described below.

InFIGS.4A and4B, the second permanent magnets39will be referred to as second permanent magnets39A,39B, and39C from the left side to the right side in the figure (A, B, and C are indices for distinguishing a position).

The first permanent magnet37located between the adjoining second permanent magnets39A and39B will be referred to as a first permanent magnet37X, and the first permanent magnet37located between the adjoining second permanent magnets39A and39B will be referred to as a first permanent magnet37Y.

As illustrated inFIG.4A, the first permanent magnet37X is placed in such a way that the top surface thereof is the N-pole and the bottom surface thereof is the S-pole, and the adjacent first next permanent magnet37Y is placed in such a way that the top surface thereof is the S-pole, and the bottom surface thereof is the N-pole.

Since the magnetic field lines are drawn in the S-pole from the N-pole, as indicated by an arrow line (1), the magnetic field lines from the N-pole of the top surface of the first permanent magnet37X are drawn in the S-pole of the nearest second permanent magnet39B.

As indicated by an arrow line (2), the magnetic field lines from the N-pole of the second permanent magnet39B are drawn in the S-pole of the nearest first permanent magnet37Y.

As indicated by an arrow line (3), the magnetic field lines from the N-pole of the first permanent magnet37Y are drawn in the S-pole of the nearest first permanent magnet37X.

Consequently, at the center second permanent magnet39B, magnetic field lines42in the clockwise direction in the figure are formed.

At the adjacent second permanent magnets39A and39C, magnetic field lines42in the counterclockwise direction in the figure are formed.

Since none of the magnetic field lines42is irrelevant to the tie bar19, the cylindrical portion33is movable to the left side or to the right side in the figure relative to the corresponding tie bar19. This state corresponds to an unconstrained state.

In order to make the cylindrical portion33into a constrained state relative to the tie bar19, a current is caused to flow through the electro-magnetic coils38so as to invert the magnetization in such a way that the top surface of the first permanent magnet37X becomes the S-pole and the bottom surface thereof becomes the N-pole. Similarly, the magnetization is inverted in such a way that the top surface of the adjacent first permanent magnet37Y becomes the N-pole, and the bottom surface thereof becomes the S-pole.

As illustrated inFIG.4B, the first permanent magnet37X and37Y are subjected to the magnetization inversion. It is sufficient that a time for causing the current to flow for the magnetization inversion is less than one second.

The magnetic field lines42from the N-pole of the center second permanent magnet39B reach the own S-pole via the nearest tie bar19like an arrow (4).

Moreover, the magnetic field lines42from the N-pole of the right first permanent magnet37Y reach the S pole of the left first permanent magnet37X via the tie bar19like an arrow (5).

Note that since the inner cylinder35formed of a steel becomes the N-pole and the S-pole, the inner cylinder35formed of a steel contributes to the formation and enhancement of the magnetic field lines42.

Although the respective magnetic field lines42relating to the right and left second permanent magnets39A and39C are in the opposite directions, those still go through the tie bar19.

Those magnetic field lines42causes the cylindrical portion33to be in the constrained state relative to the tie bar19. In the constrained state, the cylindrical portion33does not move to the right side or to the left side in the figure.

When a current in the opposite direction is caused to flow through the electro-magnetic coils38for the magnetization inversion again, the state returns toFIG.4A.

Meanwhile, the constraint force inFIG.4B changes depending on a distance D between the cylindrical portion33and the tie bar19. Such a change will be described in detail.

The inventors of the present disclosure confirmed that, as illustrated inFIG.5, with the distance D between the cylindrical portion33and the tie bar19being taken as a horizontal axis, constraint force with a gentle curve that goes down to the right side was obtained.

When it is defined that the constraint force when the distance D is 0 mm is 100%, the constraint force when the distance D was 1 mm was 83%, the constraint force when the distance D was in 2 mm was 64%, and the constraint force when the distance D was 3 mm was 50%.

Accordingly, if the distance D is several mm, a sufficient constraint force is ensured. Such a several mm will be defined as a predetermined distance.

By setting the distance D to be several mm, a mechanical contact between the cylindrical portion33and the tie bar19can be avoided, and thus a wear of the cylindrical portion33and also a wear of the tie bar19can be suppressed.

Next, actions of the mold-clamping machine10that includes the above-described constraining mechanism30will be described below.

InFIG.1, the movable mold17is separated from the stationary mold12. In order to accomplish the mold clamping, the constraining mechanism30is made into an unconstrained state, and the mold opening-and-closing mechanism16is compressed. This causes the movable mount18and the mold-clamping mechanism15to come close to the stationary mount13. This causes the movable mold17to abut the stationary mold12.

Next, the constraining mechanism30is made into a constrained state. Next, the mold-clamping mechanism15is expanded to clamp the movable mold17to the stationary mold12at high pressure.

A nozzle45of an injection apparatus44is caused to abut the stationary mold12, and a melted resin is injected from the injection apparatus44into the stationary mold12and into the movable mold17. After the resin material is cured, the constraining mechanism30is changed to the unconstrained state from the constrained state, and the mold is opened.

Next, a consumption amount of electrical energy will be discussed.

Assuming that the constrained state illustrated inFIG.4B is maintained for, for example, 60 seconds, a current flows through the electro-magnetic coil38for one second and no current flows therethrough for 59 seconds. Hence, a current-carrying rate is calculated from 1÷60=0.017, and a current-carrying time remains only 1.7% of the total. The same is true of the case illustrated inFIG.4A.

Therefore, according to this embodiment, an electrical energy consumption is quite little.

However, the magnet mechanism36that includes the first permanent magnet37, the second permanent magnet39, and the electro-magnetic coil38may be changed to a mere electrical magnet.

In the case of an electrical magnet, since the expensive permanent magnets37and39become unnecessary, the costs of the magnet mechanism36can be reduced. In the case of an electrical magnet, however, a current is continuously caused to flow therethrough during the constraint state, and thus the electrical energy consumption remarkably increases.

Therefore, in view of the electrical energy consumption, a permanent magnet is better than an electrical magnet.

Next, a modified example of the present disclosure will be described with reference toFIG.6.

As illustrated inFIG.6, the constraining mechanism30may be placed at the stationary-mount-13side. The other structures are the same as those inFIG.1, the same reference numeral as those inFIG.1are given, and the detailed description of the other structures will be omitted.

According to this constraining mechanism30, the tips of the respective cylindrical portions33protrude from the stationary mount13toward the injection apparatus44, and thus the sufficient length of each cylindrical portion33is ensured.

Note that unlikeFIG.6, the tip of each cylindrical portion33may protrude from the stationary mount13toward the movable mount18. In view of the detachment work of the stationary mold12, however, it is more preferable that the tip of each cylindrical portion33should protrude toward the injection apparatus44since a work space can be increased.

Moreover, although the horizontal type mold-clamping machine has been described in the embodiment, the present disclosure is also applicable to a vertical type mold-clamping machine.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to an alternative technology for conventional mold-clamping machines which utilize half nuts.

REFERENCE SIGN LIST

10Mold-clamping machine11Base12Stationary mold13Stationary mount15Mold-clamping mechanism16Mold opening-and-closing mechanism17Movable mold18Movable mount19Tie bar30Constraining mechanism33Cylindrical portion34Outer cylinder35Inner cylinder36Magnet mechanism37First permanent magnet38Electro-magnetic coil39Second permanent magnet42Magnetic field lines44Injection apparatusD Predetermined distance