JPH05237893A - Mold clamping device of injection molding machine - Google Patents

Abstract

PURPOSE:To certainly obtain mold clamping force without adjusting the thickness of a mold even when the thickness of the mold changes. CONSTITUTION:A movable electromagnetic plate 9 is provided on the side opposite to the moving die plate 7 of a fixed electromagnetic plate 8 so as to be movable in the direction approaching and separating with respect to the fixed electromagnetic plate 8 and electromagnet coils 12 for generating magnetic attraction are respectively provided to both electromagnetic plates 8, 9. A moving die plate driving mechanism composed of a combination of a feed screw shaft 16 and a nut member 13 is connected to the moving die plate 7 and the mold clamping operation of molds is performed by this driving mechanism. Continuously, the mold clamping operation of both molds is performed by the magnetic attraction of the electromagnet coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device for an injection molding machine, and more particularly to a mold clamping device for clamping a mold using magnetic attraction.

[0002]

2. Description of the Related Art In an injection molding machine, a die casting machine or the like, when molding a molded product, the mold must be kept in a closed state (mold closed state). In order to keep the mold closed against a large internal pressure generated in the mold, a mold clamping action of pressing the mold with a strong force from opposite sides is required. Therefore, in a molding apparatus such as an injection molding machine, a mold clamping device for maintaining a mold in a closed state during molding is installed together with an injection device for injecting a molding raw material in a molten state.

Conventionally, as this mold clamping device, as disclosed in, for example, Japanese Patent Application Laid-Open No. 61-193821, a ball screw is screwed onto a nut member attached to a moving die plate, and the ball screw is mounted on the nut member. Is known, in which the mold clamping force is controlled by controlling the compression degree of the ball screw by controlling the torque of the servo motor by rotating the motor in forward and reverse directions.

However, in this type of mold clamping device,
Since the servomotor is used to obtain the mold clamping force that requires a large force, there is a problem that a large horsepower motor is required.

Therefore, in some cases, for example, Japanese Patent Publication No. 46-25.
As disclosed in Japanese Laid-Open Patent Application No. 262 or Japanese Patent Laid-Open No. 61-154822, a mold clamping device has been proposed in which the mold is clamped by using a magnetic attraction force.

[0006]

However, in the conventional mold clamping device for clamping the mold by using the magnetic attraction force, the magnetic attraction force is generated when the thickness of the mold is changed. Since the relative position of the magnet device or the relative position of the electromagnet and the attraction unit changes, there is a problem that the mold clamping force can be obtained only at a specific position. Therefore, in this type of conventional mold clamping device, every time the mold is replaced,
There is a problem that an operation of adjusting the die thickness is required and the apparatus configuration becomes complicated, and the die replacement is not easy.

The present invention has been made in consideration of such a point, and even if the thickness of the mold is changed, the mold clamping force can be surely obtained without adjusting the mold thickness, which is troublesome. An object of the present invention is to provide a mold clamping device for an injection molding machine, which simplifies a new mold exchanging work and shortens a mold exchanging time.

[0008]

According to the present invention, as means for achieving the above object, a fixed side mold attached to a fixed die plate and a moving side mold attached to a moving die plate are provided so as to face each other. In the mold clamping device of the injection molding machine, which linearly moves the movable die plate to close the two molds and to clamp the two molds by the magnetic attraction force of the magnetic attraction force generating means, A fixed electromagnetic plate provided at a position facing the fixed die plate with a plate interposed therebetween, and a movable die plate opposed with the fixed electromagnetic plate interposed, and moved in a predetermined range relative to the fixed electromagnetic plate within a predetermined range. A movable moving electromagnetic plate, a magnetic attraction force generating means provided on at least one of the two moving electromagnetic plates, and a feed roller connected to the moving die plate. A movable die plate drive mechanism composed of a combination of a shaft and a nut member screwed with the shaft, and a tie bar installed between the fixed electromagnetic plate and the fixed die plate for guiding the movement of the movable die plate were respectively provided. It is characterized by

[0009]

In the mold clamping device of the injection molding machine according to the present invention, the feed screw shaft or the nut member is screwed forward by driving the nut member or the feed screw shaft in the forward and reverse directions by the drive source, and is integrated with this. The moving die plate of (1) is linearly moved by the tie bar to close and open both dies.

On the other hand, when the magnetic attraction force of the magnetic attraction force generating means exerts an attraction force between both electromagnetic plates in the mold closed state, this force is applied to the moving die plate via the nut member and the feed screw shaft. It is transmitted and a large mold clamping force is applied between the two molds.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an injection molding machine according to the present invention. The injection molding machine 1 is composed of an injection device 2 and a mold clamping device 3. , Mounted on a frame (not shown).

The injection device 2 is a device for injecting a molten raw material between molds 4 and 6 which will be described later, and can be moved in the left-right direction in FIG. 1 by a drive mechanism (not shown).

On the other hand, the mold clamping device 3 is provided with a fixed die plate 5 which detachably holds the fixed die 4 and a movable die plate 7 which detachably holds the movable die 6, and which is fixed. The die plate 5 is fixed on a frame (not shown), and the moving die plate 7 linearly moves with respect to the fixed die plate 5 so as to close and open the molds 4 and 6. Is becoming

Fixed die plate 5 of movable die plate 7
A fixed electromagnetic plate 8 is arranged on the opposite side to the fixed electromagnetic plate 8, and the fixed electromagnetic plate 8 is fixedly mounted on a frame (not shown). On the opposite side of the fixed electromagnetic plate 8 to the movable die plate 7, a movable electromagnetic plate 9 is arranged so as to face it.

The moving electromagnetic plate 9 is slidable in a distance direction with respect to the fixed electromagnetic plate 8 in a predetermined range by a stopper 10 mounted between the movable electromagnetic plate 8 and the fixed electromagnetic plate 8. Between 9 and 9,
An air gap G of 1 mm or less is formed in the farthest state.

As shown in FIGS. 1 to 3, for example, octagonal annular grooves 11 are provided on the opposing surfaces of the electromagnetic plates 8 and 9, respectively, and the annular grooves 11 are provided in the annular grooves 11. An electromagnet coil 12 for generating a magnetic attraction force is provided.

As shown in FIG. 4, each of the electromagnet coils 12 is continuously wound and disposed in the annular groove 11, and the position of the outermost side 12a is from the opening end of the annular groove 11. Is set in a position slightly inside, and is fixed in the annular groove 11 by solidifying the whole with synthetic resin or the like.

As shown in FIGS. 1 and 3, a small toothed pulley 14 having a nut member 13 fixedly mounted on its inner peripheral portion is rotatably attached to a central portion of the moving electromagnetic plate 9 via a bearing 15. The nut member 13 is screwed with a feed screw shaft 16 such as a ball screw having a male screw portion 17 over substantially the entire length. Then, as shown in FIGS. 1 and 2, the feed screw shaft 16 freely penetrates through an opening 18 provided in the central portion of the fixed electromagnetic plate 8, and the tip portion thereof is fixed to the movable die plate 7.

On the other hand, on the moving electromagnetic plate 9, as shown in FIG. 1, a feed motor 20 is installed via a bracket 19, and an output shaft 20a of the feed motor 20 is installed.
The toothed pulley 21 and the toothed small pulley 14 attached to the above are interlockingly connected via an endless timing belt 22. Then, the movable die plate 7 linearly moves with respect to the fixed die plate 5 by rotating the nut member 13 in the forward and reverse directions by driving the feed motor 20, thereby performing mold closing and mold opening of both the molds 4 and 6. It is like this. The feed motor 20 has a built-in brake (not shown) for locking the moving electromagnetic plate 9 to the feed screw shaft 16 in the mold closed state.

Fixed die plate 5 and fixed electromagnetic plate 8
For example, four tie bars 23 are installed between and, and the movable die plate 7 is guided by each of these tie bars 23 and slides.

Next, the operation of this embodiment will be described.

When the molds 4 and 6 are closed, the feed motor 20 is first activated to rotate the nut member 13 via the toothed pulley 21, the timing belt 22 and the toothed small pulley 14. By the way, the feed screw shaft 16
Since the tip of the movable die plate 7 is fixed to the movable die plate 7 and cannot rotate, the movable die plate 7 is guided by the tie bar 23 and linearly moves by the rotation of the nut member 13, and the movable die 6 is fixed. The mold 4 is approached and the mold is closed.

When both molds 4 and 6 are closed, the brake of the feed motor 20 is actuated, the rotation of the nut member 13 is blocked, and the moving electromagnetic plate 9 is locked to the feed screw shaft 16. At this time, a force pushing the feed screw shaft 16 to the left in FIG. 1 acts on the feed screw shaft 16 due to the reaction force at the time of mold closing, so that the moving electromagnetic plate 9 moves from the fixed electromagnetic plate 8 to the position regulated by the stopper 10. Separate.

When power is supplied to the electromagnetic coil 12 in this state, a magnetic attraction force is generated between the electromagnet coils 12. Therefore, the moving electromagnetic plate 9 is attracted to the fixed electromagnetic plate 8. This moving electromagnetic plate 9 includes a feed screw shaft 16
Since the fixed electromagnetic plate 8 is connected to the fixed die plate 5 via the tie bar 23, the magnetic attraction force between the electromagnetic plates 8 and 9 is It acts as the mold clamping force of 5, 7. This mold clamping force is adjusted by controlling the value of the current supplied to both electromagnet coils 12 to control the magnetic attraction force.

When the mold clamping work of both molds 4 and 6 is completed, the injection device 2 is brought close to the fixed die plate 5 and its nozzle is brought into contact with the cavity inlet in the mold. Then, a molten raw material, for example, a molten resin is filled in the mold.

When the injection molding work is completed, the power supply to both electromagnet coils 12 is stopped to cancel the magnetic attraction force, and at the same time, the demagnetizing current is supplied to both electromagnet coils 12 so that the magnetic flux is absorbed by the residual magnetic flux of the electromagnet poles. Extinguish the power.

Next, the feed motor 20 is rotationally driven in the direction opposite to that when the mold is closed, and the nut member 13 is rotated in the reverse direction.
As a result, the movable die plate 7 linearly moves in the direction away from the fixed die plate 5, and the molds 4 and 6 are opened.

In this way, by rotating the nut member 13 attached to the moving electromagnetic plate 9, the feed screw shaft 16 is screwed, and thereby the moving die plate 7 is moved to move the molds of both molds 4 and 6. Since the mold is closed and the mold is opened, the mold clamping force can be reliably obtained without the need to adjust the mold thickness even when the thickness of the molds 4 and 6 is changed.

Further, the feed motor 20 is in charge of only the movement of the moving die plate 7 which does not require a large force, and the mold clamping which requires a large force is performed by using the magnetic attraction force. The motor can be used as the feed motor 20, and the size and weight can be reduced.

Further, since both the electromagnetic plates 8 and 9 for generating the magnetic attraction force are arranged on the side opposite to the fixed die plate 5 with the moving die plate 7 interposed therebetween, There is no hindrance when replacing.

In the above embodiment, the case where the electromagnet coil 12 is arranged in the annular groove 11 has been described. However, as shown in FIG. 5, for example, the electromagnet coil is composed of a plurality of small electromagnet coils 32. Composed of a combination,
These small electromagnet coils 32 are connected to the electromagnetic plates 8,
Alternatively, the plurality of circular grooves 31 may be arranged in the circular groove 31 at intervals in the circumferential direction.

Further, in the above-mentioned embodiment, the case where the electromagnet coil 12 is directly arranged on each of the electromagnetic plates 8 and 9 has been described, but as shown in FIG.
A groove-shaped member 40 made of a material having a maximum maximum magnetic flux density, such as pure iron, may be arranged around the outer periphery of 2 to increase the magnetic attraction force.

In the above embodiment, the case where the electromagnet coils 12 are installed on both the electromagnetic plates 8 and 9 has been described. However, as shown in FIG. 7, for example, the electromagnet coils 12 are arranged only on the fixed electromagnetic plate 8. It may be provided. Even with such a configuration, the magnetic force lines (magnetic flux) 41 are formed across both the electromagnetic plates 8 and 9, and the desired magnetic attraction force is obtained, and the structure on manufacturing and electric wiring is simplified. Can be converted.

FIG. 8 is a view corresponding to FIG. 1 showing another embodiment of the present invention. This embodiment is the same as the above-described embodiment in that a combination of a feed screw shaft and a nut member screwed with the feed screw shaft is used as a mechanism for moving the movable die plate, but in the above-described embodiment, the nut member is rotated. In contrast to the drive, the present embodiment is different in that the feed screw shaft is rotationally driven. In the following description, the same components as those of the embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

A hollow cylindrical bracket 41 is fixedly provided at the rear end of the movable die plate 7, and extends through the fixed electromagnetic plate 8 and the movable electromagnetic plate 9 in the rearward direction. The nut member 4 is provided inside the rear side of the bracket 41.
2 is fitted and fixed, and the feed screw shaft 43 screwed to the nut member 42 is inserted from the rear side of the bracket 41,
The tip portion is rotatably supported by a bearing 44 arranged in the bracket 41. In the present embodiment, the bracket 41 and the nut member 42 are shown as separate members for convenience of manufacture, but they may be made of the same member.

A drive shaft 46 is provided at the rear end of the feed screw shaft 43.
And a key 45 is arranged between the drive shaft 46 and the feed screw shaft 43. The drive shaft 46 is supported by a bearing 47 and a thrust bearing 48 while being rotatable and restricted in axial movement. The bearing 47 and the thrust bearing 48 are held in a bearing housing 49, and the bearing housing 49 is connected to the moving electromagnetic plate 9 via a hollow cylindrical bracket 51.

A small pulley 5 with teeth is provided at the rear end of the drive shaft 46.
The toothed small pulley 52 is interlockingly connected to the toothed pulley 21 mounted on the feed motor 20 fixed to the bearing housing 49 via a timing belt 22.

The four tie bars 23 penetrate the fixed electromagnetic plate 8 and the moving electromagnetic plate 9 and extend further rearward,
A nut member 53 that restricts the backward movement of the moving electromagnetic plate 9 is screwed to the rear end thereof. A hollow cylindrical collar 54 is provided between the tie bar 23 and the moving electromagnetic plate 9.
Is intervening. The collar 54 is for ensuring an air gap G of, for example, about 1 mm between the fixed electromagnetic plate 8 and the moving electromagnetic plate 9.

In this embodiment, when the feed motor 20 is started, the rotational force is transmitted via the timing belt 22, and the drive shaft 46 is rotationally driven. The rotation of the drive shaft 46 rotates the feed screw shaft 43, and the nut member 42 screwed with the drive screw shaft 43 moves in the axial direction of the feed screw shaft 43.
The bracket 41 moves along with the movement of the nut member 42, and moves the movable die plate 7 along the tie bar 23 toward the fixed die plate 5 side.

The mold clamping after the molds 4 and 6 are closed is performed by energizing the electromagnet coil 12 to generate a magnetic attraction force and bringing both electromagnetic plates 8 and 9 close to each other, as described above. Done. That is, when the moving electromagnetic plate 9 moves to the fixed electromagnetic plate 8 side, this movement is transmitted to the moving die plate 7 via the bracket 51, the bearing housing 49, the feed screw shaft 43, the nut member 42, and the bracket 41.

In this embodiment, since the feed screw shaft 43 is driven to rotate to move the movable die plate 7, the rotary inertia is compared with the case where the nut member 42 is driven to rotate as in the above-described embodiment. Is small, which is advantageous for the rising characteristics of the feed motor 20.

[0043]

As described above, according to the present invention, the fixed electromagnetic plate and the moving electromagnetic plate are arranged on the side opposite to the fixed die plate of the moving die plate, and the nut member mounted on the moving electromagnetic plate. Since the moving die plate is moved by operating the combination mechanism of the feed screw shaft and the feed screw shaft, the mold clamping force can be surely obtained no matter how the position of the moving die plate changes. Therefore, it is not necessary to adjust the mold thickness when exchanging the mold, and the work at the time of exchanging the mold can be simplified and the working time can be shortened.

Further, since the magnetic attraction force of the magnetic attraction force generating means is used for the die clamping which requires a large force, a stable die clamping force can be obtained and the moving die plate feed mechanism can be downsized. can do.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an injection molding machine according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a fixed electromagnetic plate viewed from the air gap side.

FIG. 3 is a configuration diagram of a moving electromagnetic plate viewed from the air gap side.

FIG. 4 is a partially enlarged cross-sectional view showing a mounted state of an electromagnet coil.

FIG. 5 is an explanatory diagram showing an example in which an electromagnet coil is formed by combining a plurality of small electromagnet coils.

FIG. 6 is an explanatory view showing an example in which a material having a large maximum magnetic flux density is arranged around the outer periphery of an electromagnet coil.

FIG. 7 is an explanatory view showing an example in which an electromagnet coil is arranged only on one electromagnetic plate.

FIG. 8 is a view corresponding to FIG. 1 showing another embodiment of the present invention.

[Explanation of symbols]

 1 Injection Molding Machine 2 Injection Device 3 Mold Clamping Device 4 Fixed Side Mold 5 Fixed Die Plate 6 Moving Side Mold 7 Moving Die Plate 8 Fixed Electromagnetic Plate 9 Moving Electromagnetic Plate 10 Stopper 12 Electromagnetic Coil 13,42 Nut Member 16,43 Feed screw shaft 18 Opening 20 Feed motor 23 Tie bar 41 Bracket

Claims (2)

[Claims] 1. A fixed side mold attached to a fixed die plate and a moving side mold attached to a movable die plate are provided so as to face each other, and the movable die plate is linearly moved to close both molds. In addition, in the mold clamping device of the injection molding machine that clamps the two molds by the magnetic attraction force of the magnetic attraction force generating means, the movable die plate is provided at a position facing the fixed die plate. A fixed electromagnetic plate; a movable electromagnetic plate that is opposed to the movable die plate with the fixed electromagnetic plate interposed therebetween, and is movable in a distance to the fixed electromagnetic plate within a predetermined range; and at least one of the two electromagnetic plates. A magnetic attraction force generating means provided on one side; a nut member rotatably attached to the moving electromagnetic plate and driven to rotate forward and backward by a drive source; A feed screw shaft having a threaded portion that is screwed into the member, the tip of which is fixed to the moving die plate through an opening of the fixed electromagnetic plate; the moving die plate installed between the fixed electromagnetic plate and the fixed die plate. And a tie bar for guiding the movement of the mold, the mold clamping device of the injection molding machine. 2. A fixed die attached to a fixed die plate and a movable die attached to a movable die plate are provided so as to face each other, and the movable die plate is linearly moved to close both die. In addition, in the mold clamping device of the injection molding machine that clamps the two molds by the magnetic attraction force of the magnetic attraction force generating means, the movable die plate is provided at a position facing the fixed die plate. A fixed electromagnetic plate; a movable electromagnetic plate that is opposed to the movable die plate with the fixed electromagnetic plate interposed therebetween, and is movable in a distance to the fixed electromagnetic plate within a predetermined range; and at least one of the two electromagnetic plates. Magnetic attraction force generating means provided on one side; a feed screw shaft that is rotatably held by the moving electromagnetic plate and is driven to rotate forward and backward by a drive source; A nut member that is screwed onto a shaft and loosely penetrates the fixed electromagnetic plate and has a tip fixedly connected to the movable die plate; installed between the fixed electromagnetic plate and the fixed die plate, and moving the movable die plate. A mold clamping device for an injection molding machine, comprising: