JP7543241B2 - Mold clamping device and injection molding machine - Google Patents

Description

The present invention relates to a clamping device equipped with first and second mold plates and multiple ball screw mechanisms connecting the first and second mold plates, and an injection molding machine.

An injection molding machine or a press machine is provided with a clamping device that clamps the mold. There are various types of clamping devices, but Patent Document 1 describes a so-called two-platen clamping device. This clamping device is composed of a first and second mold platen, i.e., a fixed platen and a movable platen, four sets of ball screw mechanisms that connect these, and four mold opening and closing servo motors provided on each ball screw mechanism. When the four mold opening and closing servo motors are driven, the four sets of ball screw mechanisms are driven and the movable platen slides relative to the fixed platen. In other words, the mold is opened and closed.

Japanese Patent Application Publication No. 5-269748

The mold clamping device described in Patent Document 1 is made up of two mold platens, so the mold clamping device can be configured compactly. This has the excellent effect of making it possible to make the ground contact area relatively small. However, there are problems that need to be solved. Specifically, there is a problem of reduced performance of the mold opening and closing servo motor. The mold inevitably becomes hot as the injection material is injected into it, but the heat of the mold is conducted to the fixed platen, which also becomes hot. In the mold clamping device described in Patent Document 1, the mold opening and closing servo motor is fixed to the fixed platen, so the heat of the fixed platen is also conducted to the mold opening and closing servo motor. In other words, the mold opening and closing servo motor also becomes hot. This affects the permanent magnets, causing a problem of reduced output torque.

This disclosure provides a mold clamping device and an injection molding machine that prevent deterioration of the performance of the servo motor for opening and closing the mold.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

This disclosure is directed to a mold clamping device that includes a first and second mold platen, multiple sets of ball screw mechanisms that connect the first and second mold platen, and a servo motor for opening and closing the mold. The ball screw mechanism includes a ball screw and a ball nut, and the ball screw is rotatably supported on the first mold platen via a bearing mechanism, with its end serving as the rotating shaft of the servo motor for opening and closing the mold. Meanwhile, the ball nut is fixed to the second mold platen. This disclosure provides for the servo motor for opening and closing the mold to be provided via a heat insulating means with respect to the first mold platen.

It is possible to prevent a decrease in the performance of the servo motor for opening and closing the mold in the mold clamping device.

1 is a front view showing an injection molding machine according to an embodiment of the present invention; FIG. 1 is a perspective view showing a mold clamping device according to an embodiment of the present invention. 1 is a front cross-sectional view showing a part of a mold clamping device according to an embodiment of the present invention. FIG. 1 is a perspective view showing a heat insulating material according to an embodiment of the present invention. FIG. 11 is a perspective view of a part of a fixed platen according to a second embodiment of the present invention, showing a servo motor mounting portion where a servo motor for opening and closing a mold is mounted.

Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. To clarify the explanation, the following description and drawings have been simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. In addition, hatching has been omitted in some areas to avoid cluttering the drawings.

<Injection molding machine according to the present embodiment>
As shown in FIG. 1, an injection molding machine 1 according to this embodiment is made up of a mold clamping device 2 provided on a bed B, and an injection device 4.

<Injection unit>
First, the injection device 4 will be described. The injection device 4 is composed of a heating cylinder 6, a screw 7 contained in the heating cylinder 6, and a screw drive device 8 that drives the screw 7. The heating cylinder 6 is provided with a hopper 10, and an injection nozzle 11 is provided at the tip. The injection material is charged from the hopper 10, and when the injection material is melted by rotating the screw 7, it is metered to the tip of the screw 7. When the screw 7 is driven in the axial direction, the injection material is injected.

<Clamping device>
The mold clamping device 2 according to this embodiment is a so-called two-platen mold clamping device. That is, as shown in Fig. 2, the mold clamping device 2 is equipped with first and second mold platens 13, 14, i.e., a fixed platen 13 and a movable platen 14. The fixed platen 13 is fixed on a bed B, and the movable platen 14 is placed on linear guides 15, 15 provided on the bed B. That is, the movable platen 14 is freely slidable in a direction approaching and moving away from the fixed platen 13. As shown in Fig. 1, a fixed-side mold 16 is attached to the fixed platen 13, and a movable-side mold 17 is attached to the movable platen 14.

The mold clamping device 2 according to this embodiment is characterized in that the fixed platen 13 and the movable platen 14 are connected by four sets of ball screw mechanisms 18, 18, ... as shown in Figure 2. Each ball screw mechanism 18, 18, ... includes a ball screw 19, 19, ... and a ball nut 20, 20, ... into which the ball screw 19, 19, ... is screwed.

Although not shown in FIG. 2, the movable platen 14 has a through hole, and the ball nuts 20, 20, ... are fixed to the through hole. In other words, the ball screws 19, 19, ... are connected to the movable platen 14 via the ball nuts 20, 20, .... On the other hand, the ball screws 19, 19, ... penetrate the fixed platen 13 and are supported rotatably relative to the fixed platen 13, as will be described in detail below. The fixed platen 13 is provided with mold opening and closing servo motors 22, 22, ... and is connected to the ball screws 19, 19, .... Therefore, when the mold opening and closing servo motors 22, 22, ... are driven, the ball screws 19, 19, ... rotate and the movable platen 14 slides. In other words, the molds 16, 17 (see FIG. 1) are opened and closed.

The connection between the ball screws 19, 19, ... and the fixed platen 13 will be described. As shown in FIG. 3, a through hole 24 is opened in the fixed platen 13, and the ball screw 19 is inserted into this through hole 24. A step 25 with a reduced outer diameter is formed in the ball screw 19, and a bearing mechanism 26 is inserted into this step 25. A male thread is formed in a portion of the step 25, and a lock nut 28 is screwed into it. An annular bearing holder 29 is fixed to the fixed platen 13, and the bearing mechanism 26 is sandwiched between the bearing holder 29 on the fixed platen 13 side and the lock nut 28 on the ball screw 19 side. In this way, the ball screw 19 is rotatably attached to the fixed platen 13 via the bearing mechanism 26.

Because the ball screw 19 and the fixed platen 13 are connected in this manner, the thrust load acting between the ball screw 19 and the fixed platen 13 is received by the bearing retainer 29, the bearing mechanism 26, and the lock nut 28. Therefore, no thrust load acts on the end of the ball screw 19. The mold opening and closing servo motor 22 consists of a stator 30 and a rotor 31, and the rotor 31 is fixed to the end of the ball screw 19. In other words, no thrust load acts on the mold opening and closing servo motor 22.

<Thermal insulation>
The mold clamping device 2 according to this embodiment is characterized in that the mold opening/closing servo motor 22 is provided to the fixed platen 13 via a heat insulating means. In this embodiment, the heat insulating means is a heat insulating material 35. The heat insulating material 35 may be made of any material as long as it has heat insulating properties and heat resistance. For example, it may be made of silica wool, ceramic fiber, glass wool, etc. FIG. 4 shows the heat insulating material 35 according to this embodiment. The heat insulating material 35 is formed in a disk shape, and a hole 36 through which the ball screw 19 (see FIG. 3) passes is opened in the center. And, bolt holes 37, 37, ... for passing bolts are opened near the outer periphery of the disk of the heat insulating material 35. The mold opening/closing servo motor 22 is adapted to contact the fixed platen 13 via the heat insulating material 35, as shown in FIG. 3, and is attached by bolts 39, 39, ....

<Action of the mold clamping device>
In the mold clamping device 2 according to this embodiment, the mold opening/closing servo motor 22 is provided on the fixed platen 13 via the heat insulating material 35, so that heat from the fixed platen 13 is not easily conducted to the mold opening/closing servo motor 22. Therefore, the temperature rise of the servo motor 22 can be suppressed. The mold opening/closing servo motor 22 is provided with a permanent magnet, and the magnetic force of the permanent magnet decreases when the temperature becomes high due to so-called thermal demagnetization. However, in the mold clamping device 2 according to this embodiment, the temperature rise of the mold opening/closing servo motor 22 is suppressed, so that the decrease in output torque due to the decrease in magnetic force can be prevented. Furthermore, the electric components provided in the mold opening/closing servo motor 22 are not exposed to high temperatures, so that the decrease in lifespan can be suppressed.

<Clamping device according to the second embodiment>
This embodiment can be modified in various ways. For example, the heat insulating means can be modified. Fig. 5 shows a servo motor mounting portion 41, which is a part of the fixed platen 13A according to the second embodiment and to which a servo motor for opening and closing the mold is attached. A plurality of protrusions 43, 43, ... of a predetermined thickness are formed on the servo motor mounting portion 41. These protrusions 43, 43, ... are arranged in a ring shape as a whole, and bolt holes 45, 45, ... are formed on the tops.

The mold opening/closing servo motor 22 (see FIG. 3) is attached to the fixed platen 13 so as to be in direct contact with these protrusions 43, 43, .... When the mold opening/closing servo motor 22 (see FIG. 3) is attached to the servo motor attachment location 41 shown in FIG. 5, an air layer is formed between the mold opening/closing servo motor 22 and the fixed platen 13 by the protrusions 43, 43, .... This air layer acts as a heat insulating means, suppressing the rise in temperature of the mold opening/closing servo motor 22. Furthermore, since the protrusions 43, 43, ... are multiple and separate, the air layer is exchanged with the outside, which also has the effect of suppressing the rise in temperature. The protrusions 43, 43, ... may be attached to the fixed platen 13 as separate parts.

<Other Modifications>
In the present embodiment, there are four sets of ball screw mechanisms 18, 18, ... connecting the first and second platens, i.e., the fixed platen 13 and the movable platen 14. However, there may be two or three sets, or five or more sets.

The invention made by the inventor has been specifically described above based on the embodiments, but the present invention is not limited to the embodiments already described, and it goes without saying that various modifications are possible without departing from the gist of the invention. The multiple examples described above can also be implemented in appropriate combinations.

REFERENCE SIGNS LIST 1 injection molding machine 2 mold clamping device 4 injection device 6 heating cylinder 7 screw 8 screw drive device 10 hopper 11 injection nozzle 13 fixed platen 14 movable platen 15 linear guide 16 fixed mold 17 movable mold 18 ball screw mechanism 19 ball screw 20 ball nut 22 mold opening/closing servo motor 24 through hole 25 step portion 26 bearing mechanism 28 lock nut 29 bearing retainer 30 stator 31 rotor 35 heat insulating material 36 hole 37 bolt hole 39 bolt 41 servo motor mounting point 43 protrusion 45 bolt hole B bed

Claims (8)

First and second mold plates;
a plurality of ball screw mechanisms connecting the first and second mold plates;
a mold opening/closing servo motor that drives the ball screw mechanism,
The ball screw mechanism includes a ball screw and
a ball nut screwed onto the ball screw;
the ball screw is rotatably supported by the first die platen via a bearing mechanism, and an end of the ball screw serves as a rotation shaft of the die opening/closing servo motor,
the ball nut is fixed to the second platen;
The mold opening and closing servo motor is provided with respect to the first mold platen via a heat insulating means. The clamping device according to claim 1, wherein the ball screw mechanism consists of four sets. The mold clamping device according to claim 1 or 2, wherein the heat insulating means is made of a heat insulating material. The clamping device according to claim 1 or 2, wherein a protrusion is provided at the attachment point of the first platen to the servo motor for opening and closing the mold, forming an air layer between the first platen and the servo motor for opening and closing the mold, and the heat insulating means is the air layer. a mold clamping device that clamps the mold;
an injection device for injecting the injection material;
The mold clamping device includes first and second mold plates,
a plurality of ball screw mechanisms connecting the first and second mold plates;
a mold opening/closing servo motor that drives the ball screw mechanism,
The ball screw mechanism includes a ball screw and
a ball nut screwed onto the ball screw;
the ball screw is rotatably supported by the first die platen via a bearing mechanism, and an end of the ball screw serves as a rotation shaft of the die opening/closing servo motor,
the ball nut is fixed to the second platen;
The mold opening and closing servomotor is provided with respect to the first platen via a heat insulating means. The injection molding machine according to claim 5, wherein the ball screw mechanism consists of four sets. The injection molding machine according to claim 5 or 6, wherein the heat insulating means is made of a heat insulating material. The injection molding machine according to claim 5 or 6, wherein a protrusion is provided at the attachment point of the first platen for the servo motor for opening and closing the mold, forming an air layer between the first platen and the servo motor for opening and closing the mold, and the heat insulating means is the air layer.

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