JP3522648B2 - Electric mold clamping device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric mold clamping device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is filled in a cavity space of a mold device, and the resin is cooled and solidified in the cavity space. By doing so, a molded product is molded.

To this end, the mold device is composed of a fixed mold and a movable mold, and the toggle mechanism of the mold clamping device is operated to move the movable mold forward and backward so that the mold is brought into contact with and separated from the fixed mold. As a result, mold closing, mold clamping and mold opening of the mold device are performed.

By the way, in an electric mold clamping device in which a servomotor is used as a means for operating the toggle mechanism, the rotor of the servomotor and the ball nut are connected to each other so that the rotor rotates once. The ball screw shaft is advanced and retracted by transmitting it to the nut and rotating the ball nut. In this case, since the moment of inertia of the ball nut in the rotating direction is large, the responsiveness of the electric mold clamping device is deteriorated.
Therefore, there is provided an electric mold clamping device in which the ball nut is fixed, the rotation of the rotor is transmitted to the ball screw shaft, and the ball screw shaft is moved back and forth.

FIG. 2 is a schematic view of a main part of a conventional electric mold clamping device, FIG. 3 is a view showing a first state of a main part of a conventional electric mold clamping device, and FIG. 4 is a conventional electric mold clamping device. It is a figure which shows the 2nd state of the principal part of an apparatus.

In the figure, 12 is a toggle support and 21
Is a ball screw as a motion direction changing means, and the ball screw 21 is attached to the rear end surface S1 of the toggle support 12 via an annular fixing plate 22, and is fixed to the toggle support 12 with a ball nut 23. And a hollow ball screw shaft 24 that is screwed with the ball nut 23 to convert the rotary motion transmitted to the ball screw shaft 24 into a linear motion.

The toggle support 1 is used to move the ball screw shaft 24 forward and backward (move in the horizontal direction in the drawing).
On the rear end surface S1 of the second servo motor 1 as a drive means via the fixed plate 22 and the cylindrical spacer 26.
8 is attached. The servomotor 18 includes an annular plate 2
Casing M consisting of 7, 28 and tubular frame 29
C, attached to the frame 29, the stator core 3
2 and a stator coil 33, and a rotor 34 rotatably arranged radially inward of the stator 31, and a hollow output shaft 35 fixed to the rotor 34.

In order to transmit the rotation of the rotor 34 to the ball screw shaft 24, a disc-shaped plate 36 is fixed to the rear end (left end in the figure) of the output shaft 35, and the plate 36 is attached to the center of the plate 36. Spline shaft 3 as a transmission member
7 is attached so as to project forward (to the right in the figure). Further, the output shaft 35 and the plate 36 are provided by the bearing b1 attached to the annular plate 27 and the bearing b2 attached to the annular plate 28.
Is rotatably supported.

The spline shaft 37 and the ball screw shaft 24 are spline-engaged with each other to constitute rotation restricting means for restricting relative rotation between the spline shaft 37 and the ball screw shaft 24. Therefore, the spline shaft 37
Spline teeth are formed on the entire outer peripheral surface of the ball screw shaft 24 and on a predetermined portion of the inner peripheral surface of the ball screw shaft 24.

Further, as shown in FIGS. 3 and 4, a crosshead 41 is disposed at the front end (right end in the drawings) of the ball screw shaft 24 via a bearing b3, and the crosshead 41 is not shown. A toggle mechanism (not shown) is arranged between the movable platen and the movable platen.

A mold device including a movable mold (not shown) and a fixed mold (not shown), a fixed platen attached to the fixed mold, a movable platen, and a toggle support 1
2, the toggle mechanism, the servo motor 18, the ball screw 21, etc. constitute an electric mold clamping device.

In the electric mold clamping device having the above structure, when the mold is closed, when the servomotor 18 is driven in the positive direction and the output shaft 35 is rotated in the positive direction, the spline shaft 37 and the ball screw shaft 24 are moved. It can be rotated in the forward direction.
Here, since the ball nut 23 is fixed, as shown in FIG.
As shown in, the ball screw shaft 24 is advanced (moved to the right in the figure). Along with that, when the crosshead 41 is advanced and the toggle mechanism is operated, the movable platen is advanced and the movable mold is brought into contact with the fixed mold.

Next, when performing mold clamping, when the servo motor 18 is further driven in the positive direction, a mold clamping force is generated by the toggle mechanism, and the movable mold is pressed against the fixed mold by the mold clamping force. . At this time, a cavity space is formed between the movable mold and the fixed mold, and the resin injected from an injection nozzle of an injection device (not shown) is filled in the cavity space.

Subsequently, when the mold is opened, the servo motor 18 is driven in the reverse direction and the output shaft 35 is rotated in the reverse direction, whereby the spline shaft 37 and the ball screw shaft 24 are rotated in the reverse direction. As shown in FIG. 4, the ball screw shaft 24 is retracted (moved to the left in the drawing). Along with that, when the crosshead 41 is retracted and the toggle mechanism is operated, the movable platen is retracted, and the movable mold is separated from the fixed mold.

[0015]

However, in the above-mentioned conventional electric mold clamping device, the rotation generated by the servomotor 18 is transmitted to the ball screw shaft 24 via the spline shaft 37. However, in the axial direction, the spline shaft 37 is always held at a constant position with respect to the toggle support 12 via the ball nut 23, while the ball screw shaft 24 is arranged so as to be movable back and forth. In the entire area where the ball screw shaft 24 moves, it is necessary to make the spline shaft 37 and the ball screw shaft 24 engage with each other by spline engagement and slide.

Therefore, since it is necessary to form spline teeth on the entire outer peripheral surface of the spline shaft 37 in the axial direction, the cost of the electric mold clamping device becomes high.
Then, the moving amount of the ball screw shaft 24, that is, the stroke of the crosshead 41 is set to SK1, and the spline shaft 3
When the length of 7 is L1, it is necessary to satisfy L1> SK1. Therefore, when the toggle mechanism becomes large and the stroke SK1 becomes long, the length L1 becomes correspondingly long. As a result, the axial dimension of the spacer 26 becomes large, and the electric mold clamping device becomes large.

Further, the spline shaft 37 and the ball screw shaft 2
When the rotation is transmitted to and from 4, the contact portion between the spline shaft 37 and the ball screw shaft 24 is slid, so a load due to frictional resistance is applied to the servo motor 18, but with the rotation of the spline shaft 37. As the torque increases, the load due to frictional resistance also increases accordingly. as a result,
The crosshead 41 cannot be smoothly moved back and forth, and the mold clamping force generated by the toggle mechanism is reduced accordingly.

The present invention solves the above-mentioned problems of the conventional electric mold clamping device, can reduce the cost, can reduce the size, and can generate a sufficiently large mold clamping force. An object is to provide an electric mold clamping device.

[0019]

To this end, in the electric mold clamping device of the present invention, the driving means arranged to move forward and backward, the crosshead arranged to move forward and backward, the driving means and the aforementioned means. A support member that connects the crosshead, a ball nut fixed to the base plate, a ball nut that is rotatably supported by the crosshead, is screwed to the ball nut, and is connected to the output shaft of the drive means. And a ball screw shaft.

In another electric mold clamping device of the present invention,
Further, the output shaft is hollow.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 5 is a diagram showing a first state of the electric mold clamping device according to the embodiment of the present invention, and FIG. 6 is a diagram showing a second state of the electric mold clamping device according to the embodiment of the present invention. Is.

In the figure, 10 is an electric mold clamping device, and 11
Is a fixed platen, 12 is a toggle support as a base plate, and a tie bar (not shown) is installed between the fixed platen 11 and the toggle support 12. Reference numeral 14 denotes a movable platen which is disposed so as to face the fixed platen 11 and is movable along the tie bar (movable in the left-right direction in the drawing). The fixed mold 15 is attached to the surface facing the fixed platen 14, and the movable mold 16 is mounted to the surface of the movable platen 14 facing the fixed platen 11. In addition, the fixed mold 15 and the movable mold 16
A mold device is constituted by the above. An ejector device (not shown) is provided at the rear end of the movable platen 14 (left end in the drawing), and a servo motor 48 as a driving unit is movable back and forth behind the toggle support 12 (left in the drawing). Is installed in.

A toggle mechanism 43 is arranged between the movable platen 14 and the toggle support 12.
The toggle mechanism 43 includes a toggle lever 4 which is swingably arranged on the toggle support 12 via a pin p1.
4, via the pin p2 to the bracket 14a formed on the rear end surface (left end surface in the drawing) of the movable platen 14, and to the toggle lever 44, the pin p3.
Via a pin p4 with respect to the toggle arm 45 and the toggle lever 44, and a pin p5 with respect to the crosshead 41, which can be moved back and forth. Toggle lever 46 movably arranged
Equipped with.

Therefore, the servo motor 48 is driven,
By moving the crosshead 41 back and forth, it is possible to perform mold closing, mold clamping and mold opening of the mold device. That is, when the mold is closed, the servo motor 48 is driven in the forward direction and the crosshead 41 is moved forward (moved to the right in the figure).
By doing so, as shown in FIG. 5, the movable platen 14 can be moved forward and the movable mold 16 can be brought into contact with the fixed mold 15. The mold is closed in this way.

Subsequently, at the time of mold clamping, the servo motor 4 is
When 8 is further driven in the positive direction, the toggle mechanism 43 generates a mold clamping force multiplied by the toggle magnification, and the movable mold 16 can be pressed against the fixed mold 15 by the mold clamping force. The mold is clamped in this way. At this time, a cavity space (not shown) is formed between the movable mold 16 and the fixed mold 15, and the cavity space is filled with a resin as a molding material injected from an injection nozzle of an injection device (not shown).

Further, when the mold is opened, the servo motor 48 is driven in the reverse direction and the crosshead 41 is retracted (moved to the left in the figure), whereby the movable platen 14 is retracted as shown in FIG. The movable mold 16 can be separated from the fixed mold 15. Thus, the mold opening is performed. In this embodiment, the servo motor 48 is used as the drive means, but a general electric motor can be used instead of the servo motor 48.

Next, the operation of the electric mold clamping device 10 when the servo motor 48 is driven will be described.

FIG. 1 is a schematic view of a main part of an electric mold clamping device according to an embodiment of the present invention, and FIG. 7 is a view showing a first state of a main part of an electric mold clamping device according to the embodiment of the present invention. , Fig. 8
Is a diagram showing a second state of a main part of the electric mold clamping device in the embodiment of the present invention, and FIG. 9 is a sectional view taken along line XX of FIG.

In the figure, 12 is a toggle support and 21
Is a ball screw as a motion direction changing means, and the ball screw 21 is attached to the rear end surface S1 of the toggle support 12 via an annular fixing plate 22, and is fixed to the toggle support 12 with a ball nut 23. And a ball screw shaft 51 that is rotatably supported by the cross head 41 and screwed with the ball nut 23. The rotary motion transmitted to the ball screw shaft 51 is converted into a linear motion.

The fixing plate 22 is not always necessary if the ball nut 23 can be directly attached to the toggle support 12.

The servo motor 48 and the cross head 41 are connected by a plurality of (four in the present embodiment) rods 53 as support members. For that purpose, each rod 53 is extended through the hole 54 formed in the toggle support 12, and the crosshead 41 is provided at the front end (the right end in FIGS. 7 and 8) of each rod 53 and the rear end (FIG. 1, FIG. 1). Servo motor 48 at the left end of 7 and 8)
The casing MC of is fixed.

The servomotor 48 has the annular plates 27, 2
8, a casing MC composed of a tubular frame 29, a stator 31 mounted on the frame 29 and composed of a stator core 32 and a stator coil 33, a rotor 34 rotatably arranged radially inward of the stator 31, and Hollow output shaft 3 fixed to the rotor 34
5 is provided.

Then, in order to transmit the rotation of the rotor 34 to the ball screw shaft 51, the output shaft 35 and the ball screw shaft 51 are connected. Therefore, a disc-shaped plate 36 is fixed to the rear end of the output shaft 35, and a transmission shaft 52 as a transmission member is projected forward (to the right in FIGS. 1, 7 and 8) in the center of the plate 36. Can be installed. Further, the output shaft 35 is rotatably supported by a bearing b1 attached to the annular plate 27 and a bearing b2 attached to the annular plate 28.

Then, the transmission shaft 52 and the ball screw shaft 5
The reference numeral 1 constitutes a rotation restricting means that is spline-engaged and restricts relative rotation between the transmission shaft 52 and the ball screw shaft 51. Therefore, a recess 51a having a predetermined length is formed at the rear end of the ball screw shaft 51, and spline teeth are formed on the outer peripheral surface of the front end (right end in FIG. 1) of the transmission shaft 52 and the inner peripheral surface of the recess 51a. To be done.

Further, at the front end of the ball screw shaft 51,
As shown in FIGS. 7 and 8, a cross head 41 is arranged via a bearing b3, and a toggle mechanism 43 is arranged between the cross head 41 and the movable platen 14 (FIG. 5).

The mold device, fixed platen 11,
Toggle support 12, movable platen 14, toggle mechanism 4
3, the servomotor 48, the ball screw 21, the crosshead 41, the rod 53, and the like constitute the electric mold clamping device 10.

In the electric mold clamping device 10 having the above structure,
When the mold is closed, the servomotor 48 is driven in the positive direction and the output shaft 35 is rotated in the positive direction.
And the ball screw shaft 51 is rotated in the forward direction, and the ball screw shaft 51 is moved forward (moved to the right in FIGS. 1, 7 and 8) as shown in FIG. Along with that,
The crosshead 41 is moved forward, and the toggle mechanism 43
Is operated, the movable platen 14 is advanced.

At this time, since the crosshead 41 and the casing MC are connected by the rod 53, the servomotor 48 is advanced as the crosshead 41 advances.

Next, when performing mold clamping, the servo motor 48 is further driven in the positive direction, and the toggle mechanism 43 is driven.
The mold clamping force is generated by.

Subsequently, when the mold is opened, the servo motor 48 is driven in the reverse direction and the output shaft 35 is rotated in the reverse direction, whereby the transmission shaft 52 and the ball screw shaft 51 are rotated in the reverse direction. As shown in FIG. 8, the ball screw shaft 51 is retracted (moved to the left in FIGS. 1, 7 and 8). Along with that, when the crosshead 41 is retracted and the toggle mechanism 43 is operated, the movable platen 14 is retracted. Further, as the cross head 41 moves backward, the servo motor 48 moves backward.

In the present embodiment, the servo motor 4
The rotation generated by 8 is transmitted to the ball screw shaft 51 via the transmission shaft 52. However, as the ball screw shaft 51 advances and retracts, the servo motor 48 also advances and retracts. It is not necessary to slide the ball screw shaft 51 at the contact portion.

Therefore, the outer peripheral surface of the front end of the transmission shaft 52,
Also, since it is only necessary to form the spline teeth on the inner peripheral surface of the rear end of the ball screw shaft 51, the cost of the electric mold clamping device 10 can be reduced. When the stroke of the cross head 41 is SK1 and the length of the transmission shaft 52 is L2, L2 <SK1 can be satisfied. Therefore, even if the toggle mechanism 43 becomes large and the stroke SK1 becomes long, it is not necessary to lengthen the length L2, so that the spacer 26 (see FIG. 2) is provided between the fixed plate 22 and the casing MC as in the conventional technique.
The electric mold clamping device 10 is eliminated.
Can be miniaturized.

Further, when transmitting rotation between the transmission shaft 52 and the ball screw shaft 51, the transmission shaft 52 and the ball screw shaft 5
Since the contact portion with 1 does not slide, a load due to frictional resistance is not applied to the servo motor 48. Therefore, the crosshead 41 can be smoothly advanced and retracted, and the toggle mechanism 43 can generate a sufficiently large mold clamping force.

In this embodiment, the transmission shaft 52 and the ball screw shaft 51 are spline-engaged with each other. However, since the contact portion between the transmission shaft 52 and the ball screw shaft 51 does not slide, the key Can also be engaged by. In addition, by connecting the output shaft 35 and the ball screw shaft 51 directly or by spline engagement, the transmission shaft 5
2 can be omitted.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified within the scope of the present invention, and they are not excluded from the scope of the present invention.

[0047]

As described above in detail, according to the present invention, in the electric mold clamping device, the driving means arranged to be movable back and forth, the crosshead arranged to be movable forward and backward,
A supporting member that connects the driving unit and the crosshead, a ball nut fixed to a base plate, a ball nut that is rotatably supported with respect to the crosshead, is screwed to the ball nut, and the driving unit. And a ball screw shaft connected to the output shaft of.

In this case, by driving the driving means, the crosshead can be moved forward and backward to close the mold, close the mold, and open the mold.

Further, since it is only necessary to form spline teeth on the outer peripheral surface of the front end of the transmission shaft and the inner peripheral surface of the rear end of the ball screw shaft, the cost of the electric mold clamping device can be reduced.

Since the drive means is also moved forward and backward as the ball screw shaft is moved forward and backward, it is not necessary to increase the length of the transmission shaft even if the stroke of the crosshead becomes long, and the electric mold clamping device can be installed. It can be miniaturized.

Further, when transmitting the rotation generated by the driving means to the ball screw shaft, a load due to frictional resistance is not applied to the driving means. Therefore, the crosshead can be smoothly advanced and retracted, and the toggle mechanism can generate a sufficiently large mold clamping force.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of an electric mold clamping device according to an embodiment of the present invention.

FIG. 2 is a schematic view of a main part of a conventional electric mold clamping device.

FIG. 3 is a diagram showing a first state of a main part of a conventional electric mold clamping device.

FIG. 4 is a diagram showing a second state of a main part of a conventional electric mold clamping device.

FIG. 5 is a diagram showing a first state of the electric mold clamping device according to the embodiment of the present invention.

FIG. 6 is a diagram showing a second state of the electric mold clamping device according to the embodiment of the present invention.

FIG. 7 is a diagram showing a first state of a main part of the electric mold clamping device according to the embodiment of the present invention.

FIG. 8 is a diagram showing a second state of a main part of the electric mold clamping device according to the embodiment of the present invention.

9 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

10 Electric mold clamping device 12 toggle support 23 Ball Nut 35 Output shaft 41 crosshead 48 servo motor 51 ball screw shaft 53 rod

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 45/66 B29C 33/22 F16H 25/20 B22D 17/26

Claims (2)

(57) [Claims] 1. (a) a drive means arranged so as to move forward and backward, and (b) a crosshead arranged so that it can move forward and backward,
(C) A support member that connects the drive means and the crosshead, (d) a ball nut fixed to the base plate, and (e) a ball nut that is rotatably supported by the crosshead and is screwed with the ball nut. An electric mold clamping device having a ball screw shaft that is combined with and is connected to an output shaft of the driving means. 2. The electric mold clamping device according to claim 1, wherein the output shaft is hollow.